e21134 Background: Therapies with monoclonal antibodies targeting PD-1 and its ligands are associated with remarkable outcomes and have revolutionized cancer treatment (Honey 2017). However, patients treated with PD-1/PD-L1 blockade may develop “a primary or secondary resistance” to therapy (Sharma, Hu-Lieskovan et al. 2017). Contrary to monoclonal antibodies, chimeric B-cell cancer vaccines have the advantage of producing polyclonal B-cell antibodies that can potentially induce memory B- and T-cell responses, while reducing immune evasion and suppression. The hypothesis is that a polyclonal induced B-cell antibody response will be more effective or as effective with improved safety over current monoclonal antibody therapy. IMU-201 (PD1-Vaxx) is being developed using an active immunization approach to treat cancers that overexpress PD-L1 by inducing the production of anti-PD-1 antibodies with a peptide epitope designed to stimulate polyclonal antibodies against PD-1 (Kaumaya et al. 2020). Methods: The IMPRINTER study is an ongoing open-label dose escalation study of IMU-201 as monotherapy (Phase 1) or in combination with atezolizumab (Phase 1b) for patients with PD-L1 expressing non-small cell lung cancer (NSCLC). All patients enrolled in Phase 1 of the study must have previously received an immune checkpoint inhibitor and experienced disease progression. The primary objective is to evaluate the safety and tolerability of IMU-201 and identify the optimal biological dose (OBD). The secondary objective is to evaluate the efficacy of IMU-201 as monotherapy and in combination with atezolizumab. Humoral and cellular immunogenicity data will be evaluated, including IMU-201 and PD-1 specific antibodies (IgG, IgM), vaccine-specific cytokine levels, and regulatory and effector T and B cells. IMU-201 is administered by intramuscular (IM) injection on Day 1, Day 15, and Day 29. Dose-limiting toxicity (DLT) assessment is completed after 29 days on treatment. Tumor progression is evaluated according to RECIST 1.1 at Day 43 then every 42 days until progression or withdrawal. Results: In Phase 1, four patients were enrolled into each of the three cohorts at 10 μg/dose, 50 μg/dose and 100 μg/dose IMU-201 with no DLTs observed. In the 10 μg/dose cohort, one patient achieved CR and one patient SD; in the 50 μg/dose cohort, four patients achieved SD; and in the 100 μg/dose cohort, one patient achieved PR and two patients achieved SD. Within the 100 μg/dose cohort, one patient experienced an immune related pneumonitis after two IMU-201 administrations and discontinued from study treatment. Conclusions: IMU-201 had no observed DLT and demonstrated preliminary signs of efficacy. The study will therefore move into Phase 1b with IMU-201 being assessed in combination with atezolizumab. Clinical trial information: NCT04432207.

Abstract Aberrant activation of the Wnt signaling pathway is associated with tumorigenesis, relapse/chemoresistance, and distance metastasis in TNBC. SM08502 is a novel, oral, small-molecule pan-CLK inhibitor that has been shown to potently inhibit the Wnt signaling pathway in several preclinical cancer models. The purpose of these studies was to examine the antitumor activity of SM08502 as monotherapy and in combination with standard chemotherapy in preclinical models of TNBC. The effect of SM08502 on cell proliferation was tested 13 BC cell lines, 7 of which were TNBC derived. Cell proliferation was strongly impaired by SM08502 across all lines (average EC50=0.170 µM [0.055-0.510]). SM08502 demonstrated similar potency between HR+ and TNBC cell lines with average EC50 values of 0.202 µM (0.058-0.510) and 0.142 µM (0.055-0.240), respectively. Relative to DMSO, SM08502 (1 μM) potently inhibited Wnt pathway-related gene and protein expression (TCF7, DVL2, LRP5, and ERBB2) in TNBC cell lines. Notably, SM08502 showed little inhibitory effect on cell proliferation in normal breast cells (Hs578Bst) compared with their paired TNBC cells (Hs578T) with an EC50 of 1.517 μM and 0.080 μM, respectively. Wnt pathway-related proteins were also overexpressed in Hs578T cells relative to Hs578Bst, and SM08502 (1 µM) strongly reduced their expression. In vivo antitumor effects and tolerability of oral SM08502 (25 mg/kg QD for 20 days) were assessed in mice bearing orthotopically implanted, luciferase-expressing, TNBC (MDA-MB231)-derived xenografts (n=5 mice per group). Significant tumor growth inhibition (TGI) vs. vehicle occurred in mice treated with SM08502 (80%, p<0.01). Metastasis was assessed by ex vivo imaging utilizing luciferase activity in bilateral lungs collected at study end. Luminescence was observed in 9/10 lungs from the vehicle-treated mice. In the SM08502-treated mice, only 3/10 lungs had measurable luminescence, suggesting that SM08502 reduced lung metastasis of TNBC tumors in this model. Additionally, SM08502 (12.5 and 25 mg/kg QD), gemcitabine (G)/Nab-paclitaxel (Nab-P) (75/30 mg/kg Q7D i.p.), and SM08502 combined with G/Nab-P were tested in MDA-MB231 xenografts. SM08502 (12.5 and 25 mg/kg) and G/Nab-P alone induced strong TGI vs. vehicle (81, 86, and 91%, respectively; p<0.0001), although no tumor regressions occurred. SM08502 (12.5 and 25 mg/kg) in combination with G/Nab-P achieved improved TGI (93% and 95%, respectively; p<0.0001 vs. vehicle) and induced tumor regression in 30% (3/10) and 60% (6/10) of mice, respectively. SM08502 (25 mg/kg QD) was also assessed in 4 patient-derived xenograft (PDX) models of TNBC (Crown Biosciences). Inhibition of tumor growth was observed in all tested PDX models (average TGI=69% [60-81], p<0.01 vs. vehicle). SM08502 was well tolerated in all tested xenograft models based on body weight measurements. In summary, SM08502 potently inhibited cell proliferation and expression of Wnt pathway-related genes in TNBC cell lines. SM08502 demonstrated strong in vivo antitumor effects in TNBC xenografts and PDX models and appeared to suppress lung metastasis. Additionally, SM08502 induced tumor regression in combination with G/Nab-P in TNBC xenografts, whereas G/Nab-P alone did not. These data suggest that SM08502 as a single agent or combined with standard chemotherapy has the potential to provide clinical benefit in TNBC. A Phase 1 study assessing safety, tolerability, and pharmacokinetics of SM08502 in subjects with advanced solid tumors is ongoing (NCT03355066). Citation Format: Heekyung Chung, Lauren Sitts, Emily Creger, John Duc Nguyen, Brian Eastman, Chi-Ching Mak, Sunil KC, Betty Tam, Carine Bossard, Timothy Phalen, Steven Cha. SM08502, a novel, small-molecule CDC-like kinase (CLK) inhibitor, demonstrates strong inhibition of the Wnt signaling pathway and antitumor effects as monotherapy and in combination with chemotherapy in triple-negative breast cancer (TNBC) models [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-13-01.

Dysregulation of the cyclin D-CDK4/6-RB signaling axis is implicated in HR+ breast cancer (BC). While CDK4/6 inhibitors such as palbociclib (Palbo) have shown efficacy in this cancer type, overcoming resistance to these agents is an unmet need for patients. SM08502 has demonstrated strong antitumor activity in several preclinical cancer models and has been shown to inhibit the Wnt pathway via disruption of alternative splicing. We examined SM08502 activity in preclinical models of CDK4/6 inhibitor-sensitive and -resistant HR+, HER2-negative (HER2-) BC. In vitro, SM08502 inhibited serine/arginine-rich splicing factor 6 (SRSF6) phosphorylation and suppressed Wnt-related gene and protein expression (e.g., DVL2, LRP5, TCF7L2) in MCF7 and T47D cells (HR+, HER2-). To test SM08502 activity on CDK4/6 inhibitor-resistant HR+, HER2- BC, we generated Palbo-resistant (Palbo-R) T47D cells. Resistance was confirmed by reduced RB and ER-α expression and increased cyclin E1 expression in Palbo-R vs. parental cells. RB phosphorylation was not inhibited upon Palbo (1 μM) treatment in Palbo-R vs. parental cells. SM08502 impaired parental (EC50=0.22 µM) and Palbo-R (EC50=0.41 µM) T47D cell proliferation, while CDK4/6 inhibitors (Palbo, abemaciclib, ribociclib) were only effective on parental cells. Compared to DMSO, SM08502 induced apoptosis in parental and Palbo-R cells as measured by caspase 3/7 activation, PARP cleavage, and MCL-1 expression. Compared to DMSO and CDK4/6 inhibitors, SM08502 (1 μM) inhibited RB phosphorylation and expression of ER-α, AR, and cyclins D1 and E in parental and Palbo-R cells, demonstrating potent activity against CDK4/6 pathway activation. In vivo antitumor effects and tolerability of oral SM08502 (25mg/kg QD) alone or combined with fulvestrant (F) ± Palbo in a CDK4/6 inhibitor-sensitive model were assessed in mice bearing orthotopic MCF7 xenografts (n=8/group). Compared to vehicle, SM08502 induced greater tumor growth inhibition (TGI) than F (75 mg/kg BIW) or Palbo (50 mg/kg QD) (70% [P Citation Format: Heekyung Chung, Lauren Sitts, Chu-Chiao Wu, Brian Eastman, Chi Ching Mak, Sunil KC, Josh Stewart, Carine Bossard, Timothy J. Phalen, Steven Cha. SM08502, a novel, small-molecule CDC-like kinase (CLK) inhibitor, demonstrates strong antitumor effects and Wnt and cyclin D-CDK4/6-RB pathway inhibition in hormone-receptor-positive (HR+) breast cancer models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6401.

Abstract CRPC is associated with primary and acquired chemotherapy resistance. Loss of androgen receptor (AR) signaling or development of AR splicing variants (e.g., ARV7) in CRPC imparts resistance to standard of care (SOC) agents that target AR signaling (e.g., enzalutamide and abiraterone). Effective therapies are an unmet need for CRPC patients with treatment-resistant tumors. Aberrant Wnt pathway activation contributes to resistance to AR-targeted agents, and cytotoxic chemotherapies such as docetaxel have been shown to activate Wnt signaling in PC cells. SM08502 has demonstrated strong antitumor activity in several preclinical cancer models and has been shown to inhibit the Wnt signaling pathway via disruption of alternative splicing. Here, we examined the antitumor activity of SM08502 in preclinical models of CRPC. The effect of SM08502 on cell proliferation was tested in 5 PC cell lines. Proliferation was strongly impaired by SM08502 across all cell lines (average EC50=0.319 μM [0.191–0.462]) irrespective of their mutation profile or hormone sensitivity. Compared to DMSO, SM08502 inhibited serine/arginine-rich splicing factor 6 (SRSF6) phosphorylation and potently suppressed Wnt-related gene (LRP5, TCF7, TCF7L1) and protein expression. In vivo antitumor effects and tolerability of QD oral SM08502 were assessed in multiple xenograft models, including mice bearing 22RV1 (ARV7+) or PC3 (AR-/-) CRPC flank xenografts (n=6/group). In 22RV1 xenografts, tumor growth inhibition (TGI) was demonstrated in mice treated with 12 and 25 mg/kg SM08502 (35%, P<0.05; 73%, P<0.001, respectively) vs. vehicle at D24 of treatment. In PC3 xenografts, significant TGI was seen in mice treated with 25 mg/kg SM08502 (75%, P=0.03) vs. vehicle. In 22RV1 xenografts, no TGI was observed with 75 mg/kg abiraterone or 30 mg/kg enzalutamide treatment (-4% and 12%, respectively) vs. vehicle, which confirmed the effect of ARV7 on resistance. Similarly, no significant TGI was seen in PC3 xenografts treated with enzalutamide, abiraterone, or docetaxel (-52%, P=0.2; -60%, P=0.33; 26%, P=0.38, respectively). No combination effect on TGI was observed with 25 mg/kg SM08502 + docetaxel (90%, P<0.05), but more tumor regressions occurred with combined treatment (4/6) than SM08502 alone (2/6). SM08502 was well tolerated in all tested xenograft models (<15% bodyweight loss from baseline). In summary, SM08502 potently inhibited cell proliferation, SRSF6 phosphorylation, and Wnt-related gene expression in multiple PC cell lines. In vivo, SM08502 demonstrated strong antitumor effects in CRPC xenografts. These data suggest that SM08502 has the potential to provide clinical benefit to patients with treatment-resistant CRPC. A Phase 1 study of SM08502 in subjects with advanced solid tumors is ongoing (NCT03355066). Citation Format: Carine Bossard, Nathalia Cruz, Kevin Chiu, Brian Eastman, Chi Ching Mak, Sunil KC, Gail Bucci, Josh Stewart, Timothy J. Phalen, Steven Cha. SM08502, a novel, small-molecule CDC-like kinase (CLK) inhibitor, demonstrates strong antitumor effects and Wnt pathway inhibition in castration-resistant prostate cancer (CRPC) models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5691.

Abstract In prostate cancer, alternative splicing of mRNA and spliceosome activity are implicated in several areas of disease pathogenesis. This is exemplified by the strong association of androgen receptor splice variants with treatment resistance and poor clinical outcome in castration-resistant disease. Therefore, pharmacologic targeting of spliceosome-regulating proteins such as CLKs and serine/arginine-rich splicing factors (SRSFs) represents a novel treatment approach for prostate cancer. To evaluate the therapeutic potential of inhibiting CLK activity in prostate cancer, the association between splicing-related gene expression and survival was investigated in The Cancer Genome Atlas Prostate Adenocarcinoma (TCGA-PRAD) data collection (N=495). Survival analysis of RNA-seq data assessed 17,879 genes to measure their association with progression-free interval (PFI). Using transcript per million as the metric for normalized gene expression, age-adjusted Cox proportional hazards regression models were performed for each gene (R v3.6.0, coxph v2.43-3). A total of 3,145 genes significantly correlated with worse prognosis (P-adj<0.10, Cox coefficient >0). CLK1 (P-adj=0.0218, HR=1.5939), CLK2 (P-adj=0.001298, HR=2.1393), and SRSF2 (P-adj=0.00167, HR=3.2917) were found to be positively associated with poorer PFI, ranking 1202, 400, and 437, respectively. Reactome pathway analysis of the significant gene set showed that mRNA splicing and processing accounted for 5 of the 19 pathways that were strongly associated with poorer PFI. An additional pathway analysis (GSEA v.3.0, MSigDB v6.2) of tumors categorized by PTEN status to assess relationship with disease severity showed that mRNA splicing (P-adj=0.0243, NES=1.7714) was enriched in PTEN-null vs. PTEN-wt tumors. Other pathways of interest, including Wnt signaling (P-adj=0.0187, NES=1.846), cell cycle (P-adj=0.0124, NES=1.974), chromatin remodeling (P-adj=0.0135, NES=1.901), DNA damage repair (P-adj=0.013974, NES=1.8934), and PTEN regulation (P-adj=0.0230, NES=1.7861), were also enriched in PTEN-null tumors. Lastly, a survival analysis within all TCGA-PRAD patients showed that low CLK1 (P=0.03) and CLK2 (P=0.0004) expression, individually, were associated with a better prognosis vs. their high-expressing counterparts. Analysis of CLK3 and CLK4 expression did not reach statistical significance. Collectively, these findings revealed an association of spliceosome activity and CLK1/2 expression with aggressive disease biology in prostate cancer. A Phase 1 study of SM08502, a novel, small-molecule pan-CLK inhibitor, in subjects with advanced solid tumors is ongoing (NCT03355066). This analysis nominates prostate cancer as a tumor type worth further exploring for the clinical activity of SM08502. Citation Format: Shawn Cho, Atish D. Choudhury, Catherine Fleener, Long Do, Carine Bossard, Heekyung Chung, Timothy J. Phalen, Steven Cha. Transcriptome analysis of TCGA prostate cancer samples identifies an association of poorer survival and aggressive disease biology with CDC-like kinase (CLK) expression and spliceosome regulation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3521.

Aberrant activation of the Wnt signaling pathway is observed in ovarian cancer (OC) and is associated with chemoresistance, immune evasion, and poor prognosis. SM08502 is a novel, oral, small-molecule pan-CLK inhibitor that has been shown to potently inhibit the Wnt signaling pathway in preclinical colorectal cancer models. The purpose of these studies was to test the in vitro and in vivo activity of SM08502 in preclinical models of OC. The effect of SM08502 on cell viability was tested in 10 OC cell lines of various histotypes, including high-grade serous (HGS), serous, endometrioid, clear-cell, and teratocarcinoma lines in vitro. Cell proliferation was impaired in all cell lines by SM08502 regardless of histotype and mutation profile (average EC50=0.123 μM [0.034 – 0.275]). Relative to DMSO, SM08502 (1 μM) also potently inhibited Wnt-related gene expression (TCF7, DVL2, LRP5, and ERBB2), which correlated with inhibition of protein expression in HGSOC, endometrioid, and teratocarcinoma cell lines. Additionally, in cell lines derived from these histotypes, SM08502 strongly inhibited cyclin E1 gene and protein expression, the amplification/overexpression of which has been associated with treatment resistance and poor overall survival in HGSOC. In vivo antitumor effects and tolerability of oral SM08502 (6.25, 12.5 and 25 mg/kg QD for 15-22 days) were assessed in mice bearing OVCAR-3 (HGSOC; TP53mut), PA-1 (teratocarcinoma; N-Ras mut), and TOV-112D (endometrioid; CTNNB1mut) xenografts (n=5 mice per group). In OVCAR-3 xenografts, significant tumor growth inhibition (TGI) vs. vehicle occurred in mice treated with SM08502 12.5 mg/kg (66%, p Citation Format: Heekyung Chung, Lauren Sitts, Emily Creger, Erica Liao, Brian Eastman, Chi-Ching Mak, K.C. Sunil, Betty Tam, Gail Bucci, Josh Stewart, Carine Bossard, Timothy Phalen, Steven Cha. SM08502, a novel, small-molecule CDC-like kinase (CLK) inhibitor, demonstrates strong inhibition of the Wnt signaling pathway and antitumor effects in diverse ovarian cancer models [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr A09.

Acute myeloid leukemia (AML) with the FLT3 internal tandem duplication (FLT3-ITD) mutation accounts for ~25% of all AMLs, carries a poor prognosis, and is prone to relapse despite targeted therapy. FLT3 mutations are associated with aberrant activation of the Wnt signaling pathway, which itself is implicated in AML initiation/progression and is required for the self-renewal and survival of leukemic stem cells. CLKs regulate the activity of serine/arginine-rich splicing factors (SRSFs) that modulate spliceosome assembly, mRNA splicing, and gene expression. SM09419 is a novel, oral, small-molecule pan-CLK inhibitor that potently inhibits the Wnt pathway. These studies examined the antitumor activity of SM09419 as a single agent and in combination with targeted and standard therapies in preclinical models of FLT3-ITD AML. In MV-4-11 and MOLM-13 AML cells carrying the FLT3-ITD mutation, SM09419 dose-dependently inhibited SRSF6 phosphorylation and potently suppressed expression of Wnt pathway-related genes (CCND1, MYC, TCF7, DVL2). The effect on cell proliferation was tested in 8 AML cell lines with varying mutation profiles as well as 26 different leukapheresis-derived primary human AML cells. Proliferation was strongly impaired by SM09419 across all tested cell lines (average EC50=0.2 + 0.048 µM]); MV-4-11 and MOLM-13 cells had EC50 of 0.049 and 0.144 µM, respectively. SM09419 also potently inhibited proliferation in all primary AML cells (average EC50=0.048 + 0.0097 µM) regardless of FLT3 mutation status, cytogenetics, or AML diagnosis (de novo or relapsed/refractory). SM09419 also induced apoptosis in MV-4-11 and MOLM-13 cells, increasing caspase 3/7 activation and PARP cleavage while reducing survivin and MCL-1 expression relative to vehicle. In vivo antitumor effects and tolerability of oral SM09419 (QD) alone or combined with either midostaurin (FLT3 inhibitor) or venetoclax (BCL2 inhibitor) and/or azacitidine were assessed in FLT3-ITD xenograft models (n=5-6/group). In MOLM-13 xenografts, SM09419 (12.5 and 25 mg/kg) induced strong tumor growth inhibition (TGI) vs. vehicle at Day 14 (TGI 52% [p<0.05] and 74% [p<0.001], respectively). Midostaurin (50 mg/kg) induced significant TGI vs. vehicle (50%, p<0.05), which was increased when administered in combination with 12.5 mg/kg SM09419 (81%, p<0.001). In MV-4-11 xenografts, single-agent SM09419 (6.25, 12.5, and 25 mg/kg) induced significant TGI vs. vehicle (56% [p<0.05], 94%, and 95% [p<0.001], respectively) at Day 26 with tumor regression in all mice dosed at 12.5 mg/kg and 25 mg/kg. In a subsequent experiment, midostaurin (50 mg/kg) alone and combined with 6.25 mg/kg SM09419 for 23 days induced tumor regression in MV-4-11 xenografts (100% TGI vs. vehicle, p<0.0001). After treatment discontinuation, tumor regression was maintained in all mice (6/6) treated with the combination for 26 days, whereas tumor regrowth was immediately observed in midostaurin-treated mice. In another MV-4-11 xenograft study, the combination of 6.25mg/kg SM09419 with azacitidine (0.8 mg/kg QD) and/or venetoclax (25 mg/kg QD) induced significant TGI (95-98% vs. vehicle, p<0.001) with tumor regression at Day 26. Azacitidine + venetoclax induced 79% TGI (p<0.001), but no tumor regression was observed. The triple combination induced tumor regression in all mice and complete regressions in 4/6 mice (67%); it had a greater effect on slowing tumor regrowth after treatment discontinuation vs. a single agent or doublet. SM09419 alone or in combination was well tolerated in these xenograft models based on body weight measurements. In summary, SM09419 potently inhibited SRSF6 phosphorylation and Wnt signaling pathway activity and induced apoptosis in FLT3-ITD cell lines. It also inhibited proliferation in cell lines and primary AML cells regardless of FLT3 status. The strong in vivo antitumor effects observed as combination treatment suggest that SM09419 combined with standard therapies may provide a clinical benefit by slowing or preventing relapse in AML with a marker of poor prognosis such as FLT3-ITD. A Phase 1 study assessing safety, tolerability, and pharmacokinetics of SM09419 in subjects with advanced hematologic malignancies is being initiated. Disclosures Chung: Samumed, LLC: Employment, Equity Ownership. Creger:Samumed, LLC: Employment, Equity Ownership. Sitts:Samumed, LLC: Employment, Equity Ownership. Chiu:Samumed, LLC: Employment, Equity Ownership. Mak:Samumed, LLC: Employment, Equity Ownership. KC:Samumed, LLC: Employment, Equity Ownership. Tam:Samumed, LLC: Employment, Equity Ownership. Bucci:Samumed, LLC: Employment, Equity Ownership. Stewart:Samumed, LLC: Employment, Equity Ownership. Phalen:Samumed, LLC: Employment, Equity Ownership. Cha:Samumed, LLC: Employment, Equity Ownership.

Abstract Aberrant activation of the Wnt signaling pathway, a highly conserved signaling cascade implicated in multiple cancer hallmarks, is common in pancreatic cancer (PC) and may functionally support proliferation and tumor-forming capacity of PC cells as well as immune evasion. It may also promote fibrogenesis in the PC tumor microenvironment (TME), which is often characterized by a dense, fibrotic stroma that can contribute to treatment resistance. SM08502 is a novel, oral, small-molecule pan-CLK inhibitor that has been shown to potently inhibit the Wnt signaling pathway in preclinical colorectal cancer models. The purpose of these studies was to test the in vitro and in vivo activity of SM08502 in preclinical models of PC. SM08502 was tested against 14 PC cell lines in vitro and the compound’s antitumor potential was analyzed in Capan-1 and HPAFII xenografts in nude mice. In vitro studies included cell viability (all lines), colony formation, apoptosis, and Wnt-related gene expression assays in Capan-1, Panc1, and HPAFII. Xenograft mouse model assays included assessment of tumor growth inhibition (TGI) relative to vehicle controls for both cell lines. Additionally, xenografts of Capan-1 and HPAFII with and without co-implantation of cancer-associated fibroblasts (CAFs) were performed to model tumor stroma effects. SM08502 inhibited cell viability in all 14 cell lines (regardless of KRAS status) (EC50=0.072-0.526 μM). In Capan-1, HPAFII, and Panc1 cells, 1 μM SM08502 inhibited colony formation as well as Wnt-related gene expression by ≥50% relative to vehicle controls. In addition, SM08502 induced apoptosis as shown by elevated caspase 3/7 activity. In the HPAFII xenograft mouse model, SM08502 (25 mg/kg QD) significantly inhibited tumor growth (TGI=93%, p=0.011) and induced RECIST-defined regression in 3 of 5 mice. Notably, SM08502 administered intermittently (QOD) also significantly inhibited tumor growth (TGI=82%, p=0.011), but no regressions were observed. In the stroma modeling experiments, tumor xenografts with CAF co-implants grew larger (Capan-1, ~45%; HPAFII, ~64%) than xenografts without CAF. Despite increased tumor growth in the presence of CAFs, SM08502 (25 mg/kg QD) induced significant TGI vs. control in Capan-1 (80% and 65%; p<0.01) and HPAFII (85% and 71%; p<0.05) xenografts with or without CAF, respectively, indicating that CAFs do not affect the activity of SM08502. These data demonstrate that SM08502 potently inhibits Wnt pathway-related gene expression, has strong in vitro and in vivo antitumor activity, and shows potential to overcome the tumor-protective effects of stroma in PC. A phase 1 study assessing safety, tolerability, and pharmacokinetics of SM08502 in subjects with advanced solid tumors is ongoing (NCT03355066). Citation Format: Carine Bossard, Nathalia Cruz, Brian Eastman, Chi-Ching Mak, K.C. Sunil, Betty Tam, Gail Bucci, Josh Stewart, Timothy Phalen, Steven Cha. SM08502, a novel, small-molecule CDC-like kinase (CLK) inhibitor, downregulates the Wnt signaling pathway and demonstrates antitumor activity in pancreatic cancer cell lines and in vivo xenograft models [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr A02.

Abstract Relapse and treatment resistance rates remain high in pancreatic cancer (PC) with standard-of-care (SOC) chemotherapy regimens, although combining them with targeted drug therapies holds promise for improving treatment outcomes and clinical benefits. The Wnt signaling pathway is implicated in multiple cancer hallmarks, including immune evasion, and regulation and survival of cancer stem cells. Aberrant activation of Wnt signaling is common in PC and many other cancers, making it a therapeutic target of interest. SM08502 is a novel, oral, small-molecule pan-CLK inhibitor that potently inhibits the Wnt signaling pathway. These studies were performed to assess the tolerability and efficacy of SM08502 in combination with chemotherapy regimens including gemcitabine (G), paclitaxel (P), and nab-paclitaxel (Nab-P) in xenograft models of PC. First, the effect of oral SM08502 in combination with G or G/P on tumor growth inhibition (TGI) relative to vehicle was assessed over 20-21 days in nude mice (n=6 per group) bearing Capan-1 or HPAFII cell-line-derived xenografts. In Capan-1 xenografts, SM08502 (12.5 mg/kg QD) + G (25 mg/kg Q7D i.p.) induced significant TGI (73%, p=0.009) and was more effective than either treatment alone. In HPAFII xenografts, SM08502 (6.25, 12.5 or 25 mg/kg QD) + G/P (75/30 mg/kg Q7D i.p.) induced ≥ 92% TGI (p<0.001) and tumor regressions in ≥ 4 of 6 mice per group at all tested doses. Next, the effect of initial treatment of SOC (G/Nab-P) alone or combined with SM08502 (6.25, 12.5, or 25 mg/kg QD) on tumor regrowth during an observation phase was assessed in Capan-1 xenografts and a patient-derived xenograft (PDX) model. TGI was calculated both during (treatment phase) and up to 40 days after (observation phase) treatment relative to vehicle and SOC alone, respectively. In Capan-1, SM08502 + G/Nab-P (75/30 mg/kg Q7D) induced strong TGI (88-94%, p<0.001) and increased tumor regressions vs. G/Nab-P at the end of treatment (day 27). In the PDX model, SM08502 + G/Nab-P (50/30 mg/kg Q7D) inhibited tumor growth earlier than G/Nab-P in the treatment phase, but TGI was similar after 21 days of treatment (94-96% p<0.0001). At the end of observation in both the Capan-1 and PDX models, SM08502 + G/Nab-P significantly inhibited tumor regrowth (Capan-1, 25 mg/kg, 73.5%, p=0.003; PDX, 12.5 mg/kg, 71.4%; p=0.01). Additionally, survival was improved with all doses of SM08502 + G/Nab-P in Capan-1 xenografts (p<0.05 vs. G/Nab-P). Based on body weight measurements, all treatments were well tolerated except for SM08502 (25 mg/kg) + G/Nab-P in the PDX model (not carried through observation phase). Oral SM08502 potently inhibited tumor growth in combination with chemotherapy and extended antitumor effects in genetically distinct PC models. These data show that the combined application of SM08502 with SOC therapy has potential to provide clinical benefit in PC. A phase 1 study assessing safety, tolerability, and pharmacokinetics of SM08502 in subjects with advanced solid tumors is ongoing (NCT03355066). Citation Format: Carine Bossard, Igor Astsaturov, Nathalia Cruz, Brian Eastman, Chi-Ching Mak, K.C. Sunil, Betty Tam, Gail Bucci, Josh Stewart, Timothy Phalen, Steven Cha. Inhibition of tumor growth and post-treatment regrowth by SM08502, a novel, small-molecule CDC-like kinase (CLK) inhibitor, in combination with standard of care in pancreatic cancer models [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C09.

Mantle cell lymphoma (MCL) is a B-cell non-Hodgkin lymphoma (NHL) that accounts for ~7% of all NHL in the U.S. MCL is associated with aberrant activation of the Wnt signaling pathway, which plays a key role in the survival and maintenance of MCL-initiating cells. Many MCL patients experience relapse and subsequent disease progression due to chemoresistance following initial therapy; hence, novel therapies are needed. CLKs regulate the activity of serine/arginine-rich splicing factors (SRSFs) that modulate spliceosome assembly, mRNA splicing, and gene expression. SM09419 is a novel, oral, small-molecule pan-CLK inhibitor that potently inhibits the Wnt pathway. The purpose of these studies was to examine the antitumor activity of SM09419 in preclinical models of MCL. SM09419 potently inhibited both CLK1-CLK4 (IC50 for all <0.02 µM) and Wnt signaling pathway (average EC50=0.068 µM) activities. In REC-1 and GRANTA-519 MCL cells, SM09419 dose-dependently inhibited SRSF6 phosphorylation and potently suppressed expression of Wnt-related genes (CCND1, LEF1, TCF7) and proteins vs. vehicle. In tests on 5 MCL cell lines, cell proliferation was strongly impaired by SM09419 across all lines (average EC50=0.102 µM [0.021-0.236]). SM09419 also induced apoptosis in REC-1 and GRANTA-519 cells, increasing caspase 3/7 activation and PARP cleavage while reducing survivin and MCL-1 expression vs. vehicle. In vivo antitumor effects and tolerability of oral SM09419 (QD 20-21 days) were assessed in mice bearing REC-1 and JeKo-1 flank xenografts (n=5/group). In REC-1 xenografts, strong tumor growth inhibition (TGI) vs. vehicle occurred in mice treated with 12.5, 25, and 50 mg/kg SM09419 (TGI 88% [p<0.01], 100%, and 100% [p<0.001], respectively), and the two highest doses induced complete tumor regression in all mice from D14. Similarly, in JeKo-1 xenografts, SM09419 (12.5 and 25 mg/kg) induced significant TGI vs. vehicle (71% and 100%, respectively; p<0.0001) with complete tumor regression at 25 mg/kg, whereas acalabrutinib (50 mg/kg BID) was not efficacious (27% TGI) when tested in parallel. SM09419 25mg/kg induced reversible suppression of phospho-SRSF6 protein and inhibited Wnt pathway-related gene expression (TCF7 and DVL2) in JeKo-1 tumors in a single-dose PD study, demonstrating downstream target engagement in vivo. SM09419 was also assessed in 2 patient-derived xenograft (PDX) mouse models of MCL. PDX cells were injected intravenously and treatment was initiated upon 8-12% engraftment of human CD45+CD19+ cells in peripheral blood. In the first model, derived from a patient who was progressive after 8 modalities including ibrutinib, SM09419 (25 mg/kg QD) increased survival vs. vehicle (100% through D26 vs. 0% by D12, respectively; n=6/group) and suppressed MCL engraftment in the blood (12% at D26 vs. 69% at D8 and D12, respectively; p=0.002) and bone marrow (30% at D26 vs. 91% at D8 and D12, respectively; p=0.002). In the second model, derived from a patient refractory after ibrutinib and anti-PDL1 treatment, SM09419 (25 mg/kg QD) significantly suppressed MCL engraftment vs. vehicle in the blood (8% vs. 72%), bone marrow (20% vs. 57%), and spleen (15% vs. 96%) at D28 (study end; p<0.001 for all; n=4/group). In addition, SM09419 greatly inhibited splenomegaly vs. vehicle (0.04 g vs. 0.4 g, respectively; p<0.001). In a subsequent experiment in the same model, mice (n=7/group) were treated with 12.5 or 25 mg/kg SM09419 or vehicle for 12 weeks (to D85). Blood MCL engraftment at D41 was significantly lower in mice treated with SM09419 (40% at 12.5 mg/kg and 23% at 25 mg/kg) vs. vehicle (88%; p<0.01 and p<0.001, respectively). SM09419 dose-dependently increased survival (28.6% at 12.5 mg/kg and 85.7% at 25 mg/kg at D85) vs. vehicle (0% at D63); survival was maintained in both dose groups during post-treatment monitoring (to D99). SM09419 was well tolerated in all tested mouse models based on body weight measurements. In summary, SM09419 potently inhibited SRSF6 phosphorylation Wnt signaling pathway activity, and cell proliferation and induced apoptosis in MCL cell lines. The strong in vivo antitumor effects observed as a single agent suggest that SM09419 may provide a clinical benefit for patients with treatment-resistant or refractory MCL. A Phase 1 study assessing safety, tolerability, and pharmacokinetics of SM09419 in subjects with advanced hematologic malignancies is being initiated. Disclosures Chung: Samumed, LLC: Employment, Equity Ownership. Creger:Samumed, LLC: Employment, Equity Ownership. Sitts:Samumed, LLC: Employment, Equity Ownership. Chiu:Samumed, LLC: Employment, Equity Ownership. Mak:Samumed, LLC: Employment, Equity Ownership. KC:Samumed, LLC: Employment, Equity Ownership. Tam:Samumed, LLC: Employment, Equity Ownership. Bucci:Samumed, LLC: Employment, Equity Ownership. Stewart:Samumed, LLC: Employment, Equity Ownership. Phalen:Samumed, LLC: Employment, Equity Ownership. Cha:Samumed, LLC: Employment, Equity Ownership.

e15185 Background: Aberrant activation of Wnt signaling contributing to tumorigenesis is most commonly associated with CRC (90% harbor Wnt pathway mutations). SM08502, a novel, oral Wnt signaling pathway inhibitor, was evaluated in preclinical CRC models. Methods: In vitro Wnt signaling: assessed using TOPflash β-catenin/TCF reporter assay in SW480 human CRC cells. In vitro Wnt pathway gene expression: measured by qRT-PCR in SW480 and Wnt3a-stimulated cells (HEK-293T, IEC-6), and with the Nanostring Wnt pathway array (180 genes) across a panel of 16 CRC cell lines. In vitro cell proliferation: 17 CRC cell lines were used to test cell viability following treatment. In vivo antitumor activity: Oral SM08502 was tested in CRC mouse xenografts (SW480, HCT 116) and a PDX model over 20-21 days (QD, QOD). 24-hr pharmacodynamic (PD) analysis of Wnt pathway gene expression was done in SW480 tumor explants from mice following one 25 mg/kg dose. Results: SM08502 inhibited Wnt pathway signaling (EC50 = 46 nM) in SW480 cells. Wnt pathway gene expression was inhibited by SM08502 (0.3-3 µM) in Wnt3a-stimulated cells ( AXIN2, LEF1) and SW480 ( AXIN2, CTNNB1, LEF1, MYC, TCF7, TCF7L2) at 24 hrs ( P < .05 vs. vehicle) . Corresponding effects on protein expression were confirmed for all genes except CTNNB1, suggesting SM08502 acted independently of β-catenin. Nanostring array screening identified inhibition of LRP5, DVL2, BTRC, and ERBB2 by SM08502. Cell proliferation was inhibited in all 17 lines (avg. EC50 = 177 nM). In vivo, SM08502 was well tolerated and induced dose-dependent antitumor effects in xenografts and PDX models. Tumor growth inhibition for 25 mg/kg QD (max dose) was 83%, 56%, and 70% in SW480, HCT 116, and PDX, respectively. PD analysis showed significant inhibition ( P< .05 vs. vehicle) of TCF7, MYC, LRP5, DVL2, and BTRC expression 8 hrs post treatment. Conclusions: In preclinical CRC models, SM08502 was a potent inhibitor of Wnt pathway signaling and gene expression. It showed strong antitumor activity in human tumor models with activating Wnt pathway mutations. The safety, tolerability, and PK of SM08502 are being evaluated in an ongoing phase 1 study (NCT03355066).

Cancer stem cells (CSCs) are a rare subpopulation of quiescent tumor cells with the ability to self-renew and form new tumors (stemness) that have been identified in many tumor types, including pancreatic cancer (PC). The presence of CSCs in PC tumors may contribute to chemotherapy resistance and relapse. The Wnt signaling pathway is a highly conserved developmental pathway that has been implicated in the maintenance and survival of CSCs. Aberrant activation of Wnt signaling is common in PC where it may functionally support cell proliferation and tumor-forming capacity; therefore, this pathway is a therapeutic target of interest. SM08502 is a novel, small-molecule pan-CLK inhibitor that has been shown to potently inhibit Wnt pathway activity in preclinical studies. The purpose of these studies was to test the hypothesis that SM08502 could impair CSC viability and stemness in PC cell lines. CSC-enriched tumor spheres were generated by culturing Panc1 cells in nonadherent conditions in which most cells lacking stemness undergo anoikis (programmed cell death). These CSC-enriched Panc1 (Panc1-CSC) cell cultures were analyzed for stemness marker expression via FACS and qPCR to validate the enrichment protocol. The effect of SM08502 on spheroid formation and viability was assessed in comparison to salinomycin and napabucasin as positive controls for CSC inhibition. Inhibition of CSCs within parental PC lines (Capan-1, HPAFII, and Panc1) was assessed by 4-day pretreatment of cells in culture with DMSO or SM08502 and a 4-day recovery period followed by plating 1 or 10 cells/well in 96-well plates under nonadherent conditions and quantifying spheroid formation after 24 days. Anoikis-mediated CSC enrichment increased the percentage of cells expressing the stem cell surface protein marker CXCR4 and increased expression of multiple stemness-related genes. Treatment with either positive control compounds or SM08502 inhibited spheroid formation and decreased the viability of the Panc1-CSC cells. Notably, SM08502 was more potent by EC50 than either salinomycin or napabucasin in the cell viability assay. Expression analyses indicated that SM08502 significantly reduced stemness-related gene expression in Panc1-CSC cultures, including CD24, LGR4, and VDR (p<0.01 vs DMSO). In addition, treatment of Capan-1, HPAFII, and Panc1 cells with SM08502 strongly impaired their ability to form spheres by 8- to 12-fold vs. DMSO, indicating that CSCs within these cell line populations are sensitive to treatment with SM08502. In summary, SM08502 demonstrated anti-CSC activity against PC and appeared more potent than known CSC-inhibiting compounds. By depleting CSCs and reducing stemness in tumors, SM08502 can potentially address relapse and treatment resistance in PC. A phase 1 study assessing safety, tolerability, and pharmacokinetics of SM08502 in subjects with advanced solid tumors is ongoing (NCT03355066). Citation Format: Carine Bossard, Nathalia Cruz, Brian Eastman, Chi-Ching Mak, Sunil KC, Betty Tam, Timothy Phalen, Steven Cha. SM08502, a novel, small-molecule CDC-like kinase (CLK) inhibitor, demonstrates activity against cancer stem cell (CSC)-enriched pancreatic cancer cells and suppresses stemness in vitro [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C08.

Acute myeloid leukemia (AML) with TP53 mutation makes up ~13% of AML cases and is an aggressive, treatment-resistant subtype with dismal prognosis and limited therapeutic options. Aberrant activation of the Wnt signaling pathway is associated with AML initiation/progression and is required for the self-renewal and survival of leukemic stem cells, making Wnt signaling inhibition a potential therapeutic modality for adverse AML. CLKs regulate the activity of serine/arginine-rich splicing factors (SRSFs) that modulate spliceosome assembly, mRNA splicing, and gene expression. SM09419 is a novel, oral, small-molecule pan-CLK inhibitor that potently inhibits the Wnt pathway in a Wnt signaling reporter assay. The purpose of these studies was to examine the antitumor activity of SM09419 as a single agent and in combination with standard therapies in preclinical models of TP53 mutant (TP53mut) AML. In TF-1a and KG-1a AML cells with TP53 mutations, SM09419 dose-dependently inhibited SRSF6 phosphorylation and potently suppressed expression of Wnt-related genes (LEF1, MYC, DVL2) and proteins vs. vehicle. The effect of SM09419 on cell proliferation was tested in 6 TP53mut AML cell lines. Proliferation was strongly impaired by SM09419 across all cell lines (EC50=0.23 + 0.056 µM). SM09419 significantly induced apoptosis in TF-1a and KG-1a cells, increasing caspase 3/7 activation and PARP cleavage while reducing survivin and MCL-1 expression relative to vehicle. In addition, SM09419 potently inhibited cell proliferation when tested in 27 leukapheresis-derived human primary AML cell lines (EC50=0.046 + 0.0061 µM) regardless of TP53 status, cytogenetics, or AML diagnosis (de novo or relapsed/refractory). In vivo antitumor effects and tolerability of oral SM09419 (QD) alone or combined with cytarabine (Ara-C), venetoclax (VEN), or azacytidine (AZA) were assessed in mice bearing TP53mut flank xenografts (n=5-15/group). In TF-1a xenografts, SM09419 (12.5 and 25 mg/kg) induced significant tumor growth inhibition (TGI) vs. vehicle at D20 (TGI 55-56% [p<0.01]). VEN (50mg/kg) was not effective (3% TGI) and combining VEN with SM09419 had no additional benefit (52%-60% TGI). In Kasumi-1 xenografts, SM09419 (12.5 and 25 mg/kg), AZA (0.8 mg/kg), and VEN (25 mg/kg) induced TGI vs. vehicle of 87%, 95% (both p<0.0001), 72% (p<0.001), and 48% (NS), respectively at D18. SM09419 25 mg/kg alone induced tumor regression in 40% (2/5) of the mice. SM09419 (12.5 mg/kg) + VEN induced greater TGI vs. vehicle (96%, p<0.0001) with tumor regression in 80% (4/5) of the mice, while AZA + VEN induced 79% TGI (p<0.001) with no tumor regression. In KG-1a xenografts, single-agent SM09419 (12.5 and 25 mg/kg) and Ara-C (10mg/kg) induced significant TGI vs. vehicle (53%, 98%, and 80% [p<0.001], respectively) at D28 but VEN (12.5mg/kg) did not (35% TGI). The combination of SM09419 (12.5 mg/kg) + VEN (12.5 mg/kg) improved TGI (98%) vs. vehicle. Tumor regression was seen in all mice with single-agent SM09419 (25 mg/kg) and 12.5 mg/kg + VEN. In another KG-1a xenograft study, mice were treated with combinations of SM09419 (12.5 mg/kg), AZA (0.8 mg/kg), and VEN (25 mg/kg) for 20 days followed by 21 days of SM09419 (25 mg/kg) or vehicle maintenance in some groups. SM09419 + VEN, SM09419 + AZA, and AZA + VEN induced TGI of 95%, 64%, and 58%, respectively (all p<0.0001), with 80% (12/15) regression in SM09419 + VEN. The triplet induced 91% TGI but was not well tolerated due to GI toxicity. In the maintenance phase, SM09419 given QD or QOD greatly slowed tumor regrowth vs. vehicle at D41 in mice previously treated with SM09419 + VEN (80% and 72% TGI [p<0.001], respectively). SM09419 QD maintenance therapy also slowed tumor regrowth following AZA + VEN (p<0.0001). SM09419 alone and in combination (except with AZA + VEN) was well tolerated in all tested xenografts. In summary, SM09419 potently inhibited SRSF phosphorylation and Wnt pathway signaling and induced apoptosis in TP53mut AML cell lines. It also inhibited proliferation in cell lines and primary AML cells regardless of TP53 status. Strong in vivo antileukemic effects were observed with SM09419 as a single agent or in combination with other AML therapies, suggesting that it is a potential treatment for hard-to-treat AML subtypes such as TP53mut AML. A Phase 1 study assessing safety, tolerability, and pharmacokinetics of SM09419 in subjects with advanced hematologic malignancies is being initiated. Disclosures Chung: Samumed, LLC: Employment, Equity Ownership. Creger:Samumed, LLC: Employment, Equity Ownership. Sitts:Samumed, LLC: Employment, Equity Ownership. Chiu:Samumed, LLC: Employment, Equity Ownership. Mak:Samumed, LLC: Employment, Equity Ownership. KC:Samumed, LLC: Employment, Equity Ownership. Tam:Samumed, LLC: Employment, Equity Ownership. Bucci:Samumed, LLC: Employment, Equity Ownership. Stewart:Samumed, LLC: Employment, Equity Ownership. Phalen:Samumed, LLC: Employment, Equity Ownership. Cha:Samumed, LLC: Employment, Equity Ownership.

The Wnt/β-catenin signaling pathway is aberrantly activated in colorectal (CRC) and many other cancers, and novel strategies for effectively targeting it may be needed due to its complexity. In this report, SM08502, a novel small molecule in clinical development for the treatment of solid tumors, was shown to reduce Wnt pathway signaling and gene expression through potent inhibition of CDC-like kinase (CLK) activity. SM08502 inhibited serine and arginine rich splicing factor (SRSF) phosphorylation and disrupted spliceosome activity, which was associated with inhibition of Wnt pathway-related gene and protein expression. Additionally, SM08502 induced the generation of splicing variants of Wnt pathway genes, suggesting that its mechanism for inhibition of gene expression includes effects on alternative splicing. Orally administered SM08502 significantly inhibited growth of gastrointestinal tumors and decreased SRSF phosphorylation and Wnt pathway gene expression in xenograft mouse models. These data implicate CLKs in the regulation of Wnt signaling and represent a novel strategy for inhibiting Wnt pathway gene expression in cancers. SM08502 is a first-in-class CLK inhibitor being investigated in a Phase 1 clinical trial for subjects with advanced solid tumors (NCT03355066).

Background: The diagnosis of hypertension requires systolic blood pressure (SBP) ≥ 140 mmHg or diastolic blood pressure (DBP) ≥ 90 mmHg on at least 2 different occasions. Therefore, there is the possibility of patients with elevated BP remaining undiagnosed if not seen by the same provider. Purpose: To utilize electronic medical records (EMR) to identify patients not previously diagnosed with hypertension that have elevated blood pressure meeting criteria for a diagnosis of hypertension using a threshold of SBP ≥ 140mmHg or DBP ≥ 90 mmHg (high BP) on 2 or more occasions. Methods: This was a cross sectional design utilizing retrospective multi-year billing and clinical data from a large multi-specialty center in the Midwest. Using electronic records of all outpatient visits in each year from 2009 - 2011, patients with at least 2 visits with SBP ≥ 140mmHg or DBP ≥ 90 mmHg (2HBP) in the measurement year were identified. These patients were compared with previously identified cohorts of known hypertension patients (Known HTN) compiled using the EMR problem list. A sensitivity analysis was done using patients with high BP at 2 consecutive visits (2CHBP) and also those with high BP at 3 consecutive visits (3CHBP). We compared proportions of patients with high BP without a prior diagnosis of hypertension (UDHTN). Results: The proportion of patients with SBP ≥ 140mmHg or DBP ≥ 90 mmHg without a prior diagnosis of hypertension (UDHTN) when compared to the cohort of known patients with a diagnosis of hypertension (Known HTN) was 25% in 2009, 26% in 2010, and 28% in 2011 in the 2CHBP cohort compared to 27% in 2009, 28% in 2010, and 30% in 2011 in the 2HBP cohort and 18% in 2009, 19% in 2010 and 23% in 2011 in the 3CHBP cohort. Conclusion: About a quarter of patients meeting current thresholds on multiple and consecutive visits did not have a known diagnosis of hypertension. The use of EMR can identify these patients for commencement of appropriate management. Table 1

Background: Pracinostat is a potent oral inhibitor of histone deacetylases (HDAC’s), selective for class I, II and IV isoforms. In-vitro cytotoxicity assays in AML cell lines revealed an IC50 of <0.1µM, and the combination with azacitidine was synergistic (CI=0.44). A Phase I study of single agent pracinostat showed activity in AML and a pilot Phase II study of pracinostat in combination with azacitidine in higher risk MDS demonstrated a complete response (CR)/CR with incomplete blood count recovery (CRi) rate of 89% (Proc ASH:3821, 2012). We report initial results from a Phase II study of pracinostat with azacitidine in previously untreated, elderly AML.

Due to increased platelet destruction, patients with primary chronic immune thrombocytopenia (cITP) have increased production of new platelets, though not necessarily sufficient to preserve normal platelet counts. As a consequence, platelets in cITP patients may be young and therefore more thrombotically active (Bath & Butterworth, 1996; Butterworth & Bath, 1998; Rand & Dean, 1998). Despite thrombocytopenia, cITP patients are paradoxically shown to have a twofold higher risk of venous thromboembolism than the general population (Severinsen et al, 2011). A single study based on data from the UK General Practice Research Database (GPRD) has suggested an increased risk of arterial thrombosis (AT) in patients with ITP with an incidence rate ratio (IRR) of 1·43 [95% confidence interval (CI) 1·02–2·02] compared with an ITP-free comparison cohort (Sarpatwari et al, 2010). To address this issue further we conducted a population-based cohort study in Denmark, which has approximately 5·4 million inhabitants. Since 1968, all Danish residents have received a unique 10-digit identification number (Civil Personal Registration number), which allows unambiguous linkage between registries (Pedersen et al, 2006). Since 1977, the Danish National Registry of Patients (DNRP) has recorded all hospitalizations and, since 1995, all hospital outpatient and emergency room visits (Andersen et al, 1999). The DNRP was used to identify all Danish residents over 18 years of age who were diagnosed with ITP [International Classification of Diseases, revision 10 (ICD-10) code: D 69·3] between 1 January 1996 and 31 July 2007. The cohort was then restricted to patients with cITP by including only those with two or more hospital diagnoses of ITP over a period longer than 6 months. These patients' medical records were reviewed and only those with a verified diagnosis of cITP were included in the cohort (Heden et al, 2009). Further, we excluded patients with a registered AT diagnosis preceding the date of cITP. For included patients we searched all previous diagnoses recorded in the DNRP since 1977 to identify presence of the 19 chronic disease diagnoses included in the Charlson Comorbidity Index (Charlson et al, 1987). Comorbidity was classified as present if at least one of the 19 diagnoses was recorded at the date of cITP diagnosis. We used the Civil Registration System and the DNRP to create a comparison cohort, consisting of 10 persons from the general population for each included cITP patient matched on age, sex, and comorbidity status. We identified all patients in the cITP and comparison cohorts with a first-time diagnosis of AT recorded in the DNRP during the follow-up period. AT diagnoses recorded only at emergency departments were not included due to expected low validity of these diagnoses. For the cITP patients we obtained information on ITP-related treatment and complete blood count on the AT diagnosis date from the medical records. The incidence rate (IR) of AT per 1000 person-years was estimated for both cohorts and stratified Cox regression was used to compute IRR. We computed IR and IRR overall and stratified by sex, age (≤60 years/>60 years), and presence of comorbidity (yes/no). This study was approved by the Danish Data Protection Agency (Record no. 2007-41-1101). The statistical software package sas, version 9.2 (SAS Institute Inc., Cary, NC, USA) was used for all statistical analyses. We identified 379 patients with a cITP diagnosis and no prior history of AT and 3790 members of the general population with no prior history of AT as comparisons. The median age in both cohorts was 53 years, 240 (63%) were women, 139 (37%) were men, and 65% had no recorded comorbidity. A total of 29 AT events were identified in the cITP cohort during a total of 2551 years of follow-up (IR = 11·37 per 1000 person-years) (Table 1). The comparison cohort had 254 AT events during 27 902 years of follow-up (IR = 9·10 per 1000 person-years). The adjusted IRR of AT was 1·32 (95% CI: 0·88–1·98) for cITP patients compared with the comparison cohort. For women with cITP the IR of AT was 12·37 per 1000 person-years compared with an IR of 6·48 in the age- and comorbidity-matched women in the comparison cohort, corresponding to an adjusted IRR of 2·27 (95% CI: 1·40–3·69). Men with ITP had an IR of AT of 9·38 compared with an IR of 14·30 in age- and comorbidity-matched men in the comparison cohort [adjusted IRR = 0·58 (95% CI: 0·27–1·25)]. The IR of AT was higher in cITP patients with comorbidity than in cITP patients without comorbidity (22·67 vs. 7·76). Compared with the comparison cohort, the adjusted IRRs of AT were, however, similar [1·26 (95% CI: 0·71–2·22) in cITP patients without comorbidity and 1·39 (95% CI: 0·79–2·46) for cITP patients with comorbidity]. We retrieved clinical information on the date of AT diagnosis for 12/25 cITP patients. Of these 12 patients, four (33%) had a subnormal platelet count (41–58 × 109/l) and one had a platelet count of 431 × 109/l on the date of AT diagnosis. None of the AT events occurred in relation to splenectomy or infusion of immunoglobulin, platelets, or an erythrocyte suspension. In this cohort study, cITP patients had a higher AT rate compared with the general Danish population. However, our data indicated that while women with cITP had a more than twofold higher AT rate than women in the comparison cohort, men with cITP seemed to have a lower AT rate than men in the comparison cohort. This finding is opposite the findings in the UK GPRD study (Sarpatwari et al, 2010). We did not include information on use of medication that may be related to the risk of AT, i.e. hormone replacement therapy (Rossouw et al, 2007), and do not have an explanation for this difference between the sexes. As cITP patients have an increased risk of bleeding, clinicians may be reluctant to treat these patients with antiplatelet therapy, such as aspirin. Our results, however, suggest that cITP patients have an increased risk of ATs. Thus, preventive therapy for cardiovascular disease should be considered in cITP patients for whom there is a relevant medical or family history.

Renal impairment (RI) and events potentially leading to RI were reported in idiopathic thrombocytopenic purpura (ITP) patients with specific medications. This study was conducted to estimate the incidence rate (IR) of RI, hemoglobinuria and hemoglobinemia (HE) and characterize baseline risk factors in ITP and ITP‐free patients. Incident ITP and matched non‐ITP patients were identified from an electronic medical record database from 1990 to 2002. ITP patients were classified by the treatment first received (initiators) or ever received (users). All cohorts were followed for study outcomes. IRs were calculated and standardized by age and gender. A total of 881 ITP and 4,496 ITP‐free patients yielded 3,044 and 16,006 person‐years, respectively. The ITP cohort had a slightly higher prevalence of autoimmune diseases and infections than the ITP‐free cohort. The IR (/10,000 person‐years) for RI, hemoglobinuria and HE was 14.2, 35.7, and 7.1 in the ITP cohort; 10.0, 48.8, and 0 in the ITP‐free cohort; and 18.3, 37.1, and 6.1 in untreated ITP patients, respectively. The risk of RI, HE or hemoglobinuria was not found to differ substantially between ITP and non‐ITP patients or across ITP treatments. Am. J. Hematol., 2011. © 2011 Wiley‐Liss, Inc.

Metastatic breast cancer remains a major treatment challenge. The use of high-dose chemotherapy (HDCT) with rescue by autologous mobilized peripheral blood (MPB) is controversial, in part because of contamination of MPB by circulating tumor cells. CD34(+)Thy-1(+) selected hematopoietic stem cells (HSC) represent a graft source with a greater than 250,000-fold reduction in cancer cells. Here, we present the long-term outcome of a pilot study to determine feasibility and engraftment using HDCT and purified HSC in patients with metastatic breast cancer. Twenty-two patients who had been treated with standard chemotherapy were enrolled into a phase I/II trial between December 1996 and February 1998, and underwent HDCT followed by rescue with CD34(+)Thy-1(+) HSC isolated from autologous MPB. More than 12 years after the end of the study, 23% (5 of 22) of HSC recipients are alive, and 18% (4 of 22) are free of recurrence with normal hematopoietic function. Median progression-free survival (PFS) was 16 months, and median overall survival (OS) was 60 months. Retrospective comparison with 74 patients transplanted between February 1995 and June 1999 with the identical HDCT regimen but rescue with unmanipulated MPB indicated that 9% of patients are alive, and 7% are without disease. Median PFS was 10 months, and median OS was 28 months. In conclusion, cancer-depleted HSC following HDCT resulted in better than expected 12- to 14-year PFS and OS in a cohort of metastatic breast cancer patients. These data prompt us to look once again at purified HSC transplantation in a protocol powered to test for efficacy in advanced-stage breast cancer patients.

Few data exist on the long-term prognosis of patients with chronic primary chronic immune thrombocytopenia (ITP). We examined the risk of infections, hemorrhage resulting in hospitalization, hematologic malignancies, and total and cause-specific mortality among patients with ITP compared with the general population. We used population-based medical databases to identify 407 patients with primary chronic ITP diagnosed during 1996 to 2007 and 4069 general population members individually matched on age, sex, and comorbidity level. We used Cox regression analysis to estimate rate ratios (RRs) adjusted for age (≤ 60 or > 60 years), sex, calendar year, and level of comorbidity. The adjusted 1-year RR of infection was 4.5 (95% confidence interval [CI], 3.3-6.1) for patients with chronic ITP compared with the general population cohort. The adjusted RR decreased to 1.8 (95% CI, 1.3-2.5) for the second to fifth year of follow-up. The adjusted 5-year RR was 3.2 (95% CI, 1.2-9.0) for hospitalized intracranial hemorrhage, 4.4 (95% CI, 2.3-8.3) for other hospitalized hemorrhages, and 4.7 (95% CI, 1.7-12.7) for hematologic malignancy. The 5-year all-cause mortality RR was 2.3 (95% CI, 1.8-3.0). In summary, primary chronic ITP was associated with substantially increased long-term risk of infections, hemorrhagic episodes requiring hospitalization, hematologic malignancies, and mortality.