Three-dimensional (3D) cell culture has been used in many fields of biology because of its unique advantages. As a representative of the 3D systems, 3D spheroids are used as building blocks for tissue construction. Larger tumor aggregates can be assembled by manipulating or stacking the tumor spheroids. The motivation of this study is to investigate the behavior of the cells distributed at different locations of the spheroids in the fusion process and the mechanism behind it. To this aim, spheroids with varying grades of maturity or age were generated for fusion to assemble micro-tumor tissues. The dynamics of the fusion process, the motility of the cells distributed in different heterogeneous architecture sites, and their reactive oxygen species profiles were studied. We found that the larger the spheroid necrotic core, the slower the fusion rate of the spheroid. The cells that move were mainly distributed on the spheroid's surface during fusion. In addition to dense microfilament distribution and low microtubule content, the reactive oxygen content was high in the fusion site, while the non-fusion site was the opposite. Last, multi-spheroids with different maturities were fused to complex micro-tissues to mimic solid tumors and evaluate Doxorubicin's anti-tumor efficacy.

Abstract Background: The use of new potent targeted therapies in prostate cancers has led to the resistance and development of highly aggressive variant prostate cancers (AVPC), including neuroendocrine prostate cancers (NEPC). N-MYC and C-MYC oncogenes overexpress in all aggressive prostate cancers (PCa). This overexpression is highly prevalent in these lethal subtypes of cancers, detected in 2% of all Prostate Cancers and over 10-17% of mCRPC patients. Transcriptional targets of CDK9 are MYCs, which act as an oncogenic driver, sufficient to transform human-derived prostate cancer cells to take on AVPC and NEPC phenotypic changes. Additionally, N-MYC and C-MYC play key roles in tumor drug resistance, and their downregulation, through CDK9 inhibition or degradation lowers tumor growth. Our efforts have demonstrated that targeting drivers of NEPC and mCRPC with highly selective CDK9 molecular glue degraders SLX-3064 SLX-3065 was designed from reversible SLX-3039 for therapeutic intervention of mCRPC, AVPC, and NEPCs. Materials and Methods: We employed our MolecuLernTM-trained molecular glue library design strategies and in vitro CDK9 kinase binding assays. Other experiments include cellular efficacies of single-agent Molecular Glue degraders and their effect in combination experiments on 22Rv1, LASCPC-01, C4-2, and C4-2B MYC expressed PCa cells. Kinase selectivity, Nano BRET, ADME-Tox, in vitro safety, secondary pharmacological assays, Cell engraftment mouse tumor mode, and PK studies were performed. Results: We designed and synthesized a series of novel small molecule CDK9 Molecular Glue degraders based on our initial CDK9 inhibitor lead SLX-3030 and SLX-3039. The SLX-3064 and SLX-3065 reversibly bind to CDK9 with an IC50 of 9 and 7 nM in kinase binding, in target engagement assays, elicit pharmacological responses in N-MYC, C-MYC, driven prostate cancer cells in vitro in LASCPC-01 (21, 35 nM), 22Rv1 (108, 236 nM), C4-2B (15, 12 nM), C4-2 (2.7, 1.5 nM) and VCap (86, 73 nM) cell lines. SLX-3064 and SLX-3065 exhibited potent activity degrading total, pCDK9, MYCs, Mcl-1, and its downstream RNA Pol II, Ser 2, 5, 7, and pAR Ser-81 in a dose-dependent manner. Additionally, we performed in vitro ADME-Tox, hERG, P450, safety panel screen, and in vivo PK experiments in rodent and beagle dog species. Conclusion: In summary, both SLX-3064 and SLX-3065 molecular glues display complete degradation of CDK9 and its downstream markers, and these degraders possess ideal developable criteria as oral agents. With these characteristics, SLX-3065 was selected as a candidate that had the appropriate developable properties and our plans for conducting additional IND-enabling studies and future clinical trial plans will also be discussed. Citation Format: Chenyu Lin, Zhaoliang Li, Kyle Medley, David J. Bearss, Hariprasad Vankayalapati. Discovery of an oral, potent, and selective CDK9 molecular glue degrader SLX-3065 active in aggressive variant prostate cancers (AVPC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB161.

Background: Acute promyelocytic leukemia (APL) is one of the most treatable leukemias in the current era, with cure rates upwards of 90%. Early mortality due to coagulopathies often seen at diagnosis is a major driver of adverse outcomes. Prompt initiation of all-trans retinoic acid (ATRA) is crucial for suspected APL, as it is known to reverse these coagulopathies. Chemotherapy-free protocols consisting of arsenic trioxide (ATO) and ATRA have become the standard of care for low-risk APL with high cure rates and reduced hematologic toxicities. For high-risk disease, there are multiple treatment options that have not been compared. Since APL is rare, there is a lack of real-world data for this disease. This retrospective review aimed to assess the outcomes of APL patients (pts) across multiple institutions and to examine the most common induction regimens, characteristics linked to early (30-day) mortality, and supportive care strategies. Methods: This retrospective study involved 9 institutions in the US and was conducted through the Consortium on Myeloid Malignancies and Neoplastic Diseases (COMMAND). Data included pts admitted from 8/5/2006 through 2/3/2024 with a confirmed diagnosis of APL. Each institution received a data-collection form and contributed data on APL pts from presentation to last follow-up. Key data categories included patient demographics, presenting laboratory and molecular data, treatment regimen, supportive care, and patient outcomes. Results: Data for 412 pts were identified with a median age of 51 (range 17-90) and 49% were female. Cardiovascular comorbidities were present in 44% of pts and 16% had a known pulmonary comorbidity. At presentation 109 (27%) had high risk-disease, defined as a white blood cell count (WBC) greater than 10 x 109/L. A FLT3 mutation was seen in 50% of tested pts, WT1 (22%), KRAS (3.6%), and NRAS (6.5%). The median WBC at presentation was 2 x 109/L (range: 0-166 x 109/L) and the median platelet count was 27 x 109/L (range: 2.0-315 109/L). Twenty-six percent presented with grade 2+ thrombosis, bleeding, or both. A higher percentage of pts with high-risk vs. low-risk disease presented with grade 2+ thrombosis, bleeding, or both (43% vs. 20%), DIC (60% vs. 36%), and mutated FLT3 (81% vs. 37%). The majority of pts received a chemotherapy-free induction regimen consisting of ATRA plus ATO. It was determined that 36 (8.7%) pts received induction with intermittent ATO plus ATRA (Burnett AK, Lancet Oncol 2015), 276 (67%) received daily ATO plus ATRA (Ravandi F, J Clin Oncol 2009 and Lo Coco, NEJM 2013), and 70 (17%) received a regimen inclusive of an anthracycline plus ATRA. Eleven pts did not start an induction regimen other than single-agent ATRA due to early death, while 19 had their regimen classified as “other” because they did not follow a conventional induction path. In total, 295/358 (82%) received ATRA within 24 hours of admission. At least 1 dose of gemtuzumab ozogamicin was given to 58 (14%) pts, of which 35 (60%) were considered high risk. The incidence of differentiation syndrome (DS) was 37% (n=154). Among the 243 pts who received steroid prophylaxis, 30% developed DS, compared to 52% of those who did not receive prophylaxis. Among the 360 pts with at least 1 available PCR result after starting induction, 94% achieved PCR-negativity. The 30-day mortality rate was 6.6%. On univariate analysis, presenting variables associated with a higher 30-day mortality include older age, diabetes, cardiovascular comorbidities, thrombosis or bleeding, DIC, eGFR < 60, elevated total bilirubin and D-dimer levels, and high-risk disease. The median overall survival (OS) of the cohort was not reached, and the 5- and 10-year OS was 88% (95% CI: 84-91%) and 79% (95% CI: 72-87%) respectively. The cumulative incidence of relapse at 3 years was 2.7% (95% CI: 1.4 - 5.1%), with no additional relapses observed. The incidence of CNS relapse at 3 years was 0.9% (95% CI: 0.3% - 2.8%), with 2 of the 4 pts classified as high-risk. Conclusion: This is the largest real-world evidence data collection in the US evaluating the outcome of pts with APL in the current era, inclusive of ATO as front-line induction. Outcomes for this disease remain extremely positive, with low 30-day mortality rates noted in this study along with durable OS rates and low incidence of relapse. Additional information on outcomes, safety, and supportive care will be presented at the meeting.

Introduction: Brexucabtagene autoleucel (brexu cel) is a CD19-targeted chimeric antigen receptor (CAR) T cell therapy approved for the treatment of adults with relapsed/refractory (R/R) acute lymphoblastic leukemia (ALL). Some patients (pts) proceed with a consolidative allogeneic hematopoietic cell transplant (HCT) after breux cel. We do not know which pts can safely avoid a consolidative HCT and its associated morbidity. Methods: We conducted a retrospective cohort study utilizing the Real-World Outcomes Collaborative of CAR-T in Adult ALL (ROCCA) dataset. ROCCA is a registry of brexu cel pts in 32 centers in North America. We defined complete remission (CR) as < 5% blasts in the bone marrow and no central nervous system (CNS) or extramedullary (EM) disease on or around D28 after brexu cel. We defined measurable residual disease negative (MRD-) CR as CR and no abnormal blasts in the bone marrow by multiparameter flow cytometry, quantitative polymerase chain reaction, ClonoSeq next generation sequencing (NGS), or other sequencing modalities with lower sensitivity. ClonoSeq NGS has a sensitivity of 10-6, while the other modalities have a sensitivity of at least 10-4. We defined progression free survival (PFS) as the time from CAR-T infusion to relapse or death, censored at the date of last follow-up. Statistical analyses were performed in R. Univariable Cox proportional hazards regression analyses were performed to determine the association of pre-specified variables with PFS. Variables known to be associated with CAR T outcomes in ALL were entered into a multivariable model. HCT was incorporated as a time-varying covariate. Results: During the study period, 281 pts were infused with brexu cel. We focused our analysis on 172 (61%) pts with confirmed MRD- CR on D28, as that is the group with clinical equipoise regarding maintenance strategy. 38 (22%) of those pts received a consolidative HCT, 30 (17%) received another form of maintenance therapy (primarily tyrosine kinase inhibitors for Philadelphia (Ph)-chromosome positive ALL), and 104 (60%) pts received no maintenance therapy. Pts who underwent consolidative HCT were younger (median age 35 years) than those who received no maintenance (42y) (p = 0.023) and were less likely to have a history of prior HCT (13% vs. 47%, p < 0.001). No differences were observed with respect to sex, TP53 mutation status, prior inotuzumab (ino) or blinatumomab (blina) exposure, disease burden prior to CAR, or development of any cytokine release syndrome (CRS) or any neurotoxicity with brexu cel. We performed univariable Cox proportional hazard regression analyses among pts in MRD- CR on D28, excluding those who received other maintenance therapy besides HCT; the median follow up was 8.1 months. In univariable analyses, D28 MRD negativity by ClonoSeq NGS (versus MRD negativity by other, less sensitive methods), development of CRS, and pre-CAR BM blasts < 5% were associated with improved PFS; prior ino exposure was negatively associated with PFS (p < 0.05). Age, sex, Ph status, TP53 status, and neurotoxicity development were not associated with PFS. In a multivariable model incorporating ALL type, prior HCT, prior ino/blina, and pre-CAR blast burden, as well as consolidative HCT as a time-varying covariate, only MRD negativity by ClonoSeq NGS with at least 10-6 sensitivity retained statistical significance (PFS hazard ratio 0.34, 95% confidence interval (CI) 0.15-0.77, p = 0.005). Pts who were MRD- by ClonoSeq NGS on D28 and received no maintenance had favorable 6m PFS of 76% (95% CI: 59-98%) and OS of 100% with a median follow up of 6.3 months in this subgroup. Among those in MRD- CR by NGS, HCT as a time-varying covariate was not associated with improved PFS (HR 0.6, p = 0.6). Conclusions: In a large real-world cohort of adults with R/R B-ALL infused with brexu cel, we identified practice variation regarding the use of consolidative HCT. Among brexu cel recipients who entered an MRD- CR, we identified ClonoSeq NGS MRD negativity as a novel predictive factor of favorable oncologic outcomes, even without a consolidative HCT. Similar results have been obtained in pediatric ALL patietns ftreated with 41BB-based tisagenleucleucel (Pulsipher et al., Blood Cancer Discovery 2022). Longer follow-up is needed to validate the safety of omitting consolidative HCT in such pts, but these results encourage the potential for definitive therapy with brexu cel when D28 ClonoSeq NGS MRD is negative.

Introduction: There is limited data on the outcomes and tolerability of Bruton Tyrosine Kinase (BTK) inhibitors for chronic lymphocytic leukemia (CLL) in patients with severe renal dysfunction, particularly older adults. The most commonly prescribed BTK inhibitor, ibrutinib, is believed to be safe for mild to moderate renal dysfunction. However, severe renal failure has been excluded from prospective studies, and there is no guidance on dosing under the FDA label. Furthermore, ibrutinib itself can cause kidney injury and worsen existing renal dysfunction. This national Veterans Affairs (VA) analysis aims to review the safety and tolerability of BTK inhibitors in severe renal impairment. Methods: An electronic query of the VA Corporate Data Warehouse and retrospective chart review were performed to identify patients with CLL treated with a BTK inhibitor between 2013-2022 and who had severe chronic kidney disease defined as an estimated glomerular filtration rate (eGFR) < 30 ml/min/1.73 m 2 overlapping with their treatment period. Isolated acute kidney injuries lasting < 1 month were excluded. Fisher's exact test was utilized to evaluate categorical variables, logistic regression for binary outcomes, and log-rank and Cox regression for time-to-event analyses. Results: A total of 115 patients across 68 VA medical centers received 124 lines of BTK inhibitors with an eGFR < 30 (Table 1). The median duration of follow-up from the start of therapy was 26 months (range, 0.5 - 94). The median age was 74, and 98% were male, reflecting the U.S. veteran population. 64% had an eGFR < 30 at the start of therapy, with 18% requiring dialysis, while the remaining 36% experienced progressive renal dysfunction during treatment. The oral BTK agents prescribed were ibrutinib ( n = 103), acalabrutinib ( n = 18), and zanubrutinib ( n = 3). Most BTK inhibitors (n = 94 of 124 lines, 76%) were initiated at the FDA-label dose. 46 (37%) later required dose reduction, primarily due to drug toxicity ( n = 37). The most common reasons for dose reduction were cytopenia ( n = 10), failure to thrive ( n = 6), bleeding ( n = 5), and worsening renal function ( n = 5). Discontinuation of therapy for toxicity occurred in 50% (ibrutinib), 39% (acalabrutinib), and 33% (zanubrutinib). The most common reasons for discontinuation were infection ( n = 15), bleeding ( n = 10), arrhythmia ( n = 9), and disease progression ( n = 9). Among patients who received ibrutinib ( n = 103), the median progression-free survival (PFS) and overall survival (OS) were 45 and 49 months, respectively. In multivariate Cox regression, covariates associated with shorter PFS included the baseline severity of renal failure (HR 1.85, 95% CI 1.21 - 2.88), cirrhosis (HR 6.36, 95% CI 1.45 - 19.76), and heart failure (HR 4.20, 95% CI 1.82 - 9.47). Younger age, dialysis, and absence of atrial fibrillation at the start of therapy were protective in univariate but not multivariate models. Heart failure and cirrhosis retained their prognostic impact on OS in multivariate modeling. Factors including race, rural residence, obesity, IGHV status, and TP53 deletion were not significantly associated with survival in this cohort. The median duration of therapy of ibrutinib was 33 months. Ibrutinib dose reductions at initiation or during treatment were associated with a longer duration of therapy (Figure 1). Of note, dose reductions did not significantly reduce the response rate to ibrutinib or worsen survival. Interestingly, 11 patients had CLL-related kidney dysfunction. However, kidney function did not improve after treatment with a BTK inhibitor in any of the 115 patients. Progression of renal impairment was observed in 51 patients (50%) on ibrutinib, 8 (44%) on acalabrutinib, and none on zanubrutinib. The etiology of worsening renal function was uncertain for the majority of patients. Conclusion: The clinical outcomes of BTK inhibitors in patients with CLL and severe renal dysfunction have not been well-described. In our real-world data analysis, these agents appear to be a reasonable therapeutic option in severe renal impairment, including in older adults and those on dialysis. Lab monitoring is needed, given the risk of worsening renal function. Dose modifications may help improve tolerability without reducing efficacy. Unfortunately, severe renal dysfunction is unlikely to improve with CLL treatment, even in CLL-related kidney failure.

Background: Comprehensive genomic profiling (CGP) is frequently adopted to direct the clinical care of myeloid neoplasms and solid tumors, but its utility in the care of lymphoid and histiocytic cancers is less well defined. Methods: In this study, we aimed to evaluate the frequency at which mutations identified by CGP altered management in non-myeloid hematologic malignancies. We retrospectively examined the CGP results of 105 samples from 101 patients with non-myeloid hematologic malignancies treated at an academic medical center who had CGP testing between 2014 and 2021. Results: CGP revealed one or more pathogenic or likely pathogenic variant in 92 (88%) of samples and 73 (72%) of tested patients had one or more mutations with diagnostic, prognostic, or therapeutic significance. The identification of a resistance variant resulted in the suspension of the active treatment or affected subsequent treatment choice in 9 (69%) out of 13 patients. However, the presence of a therapy sensitizing variant only led to consideration of a biomarker-directed therapy in 6 (10%) out of 61 patients. Conclusions: Overall, CGP of non-myeloid hematologic malignancies identified clinically significant variants in 72% of patients and resulted in a change in management in 22% of patients.

The effect of prior inotuzumab ozogamicin (InO) treatment on brexucabtagene autoleucel (brexu-cel) outcomes remains unclear in adults with acute lymphoblastic leukemia (ALL), particularly the influence off previous InO response and the timing of administration. We conducted a retrospective multicenter analysis of 189 patients with relapsed/refractory (r/r) ALL treated with brexu-cel. Over half of the patients received InO before brexu-cel (InO-exposed). InO-exposed patients were more heavily pretreated (p= 0.02) and frequently had active marrow disease pre-apheresis (p= 0.03). Response rate and toxicity profile following brexu-cel were comparable for InO-exposed and InO-naïve; however, consolidation therapy post brexu-cel response was utilized at a higher rate in InO-naïve patients (p= 0.005). With a median follow up of 11.4 months, InO-exposed patients had inferior progression-free survival (PFS) (p=0.013) and overall survival (OS) (p=0.006) in univariate analyses; however, prior InO exposure did not influence PFS (HR 1.20, 95%CI, 0.71-2.03) in multivariate models. When InO-exposed patients were stratified according to prior InO response, InO responders had superior PFS (p=0.002) and OS (p<0.0001) relative to InO-refractory. The timing of administering InO did not affect brexu-cel outcomes, with comparable PFS (p=0.51) and OS (p=0.86) for patients receiving InO as bridging therapy or pre-apheresis. In conclusion, while InO exposure was associated with inferior survival outcomes following brexu-cel in unadjusted analyses, these associations were no longer significant in multivariate analyses, suggesting it is unlikely that InO negatively impacts brexu-cel efficacy. Our data instead imply that InO-exposed recipients of brexu-cel tend to be higher-risk patients with intrinsic adverse leukemia biology.

Introduction: TP53 mutations are found in 18% of adult patients (pts) with acute lymphoblastic leukemias (ALL), and portends poor prognosis (Saygin, Blood Cancer Discov 2024). TP53 mutations are often associated with low hypodiploidy and Li Fraumeni syndrome (germline) in children. However, we and others have shown that TP53-mutant (TP53-m) ALL arises from pre-existing TP53-m clonal hematopoiesis in adults as opposed to germline origin. The impact of co-occurring mutations, TP53 allelic frequency (AF) and different types of treatment on outcomes of TP53-m ALL are not fully characterized. We set out to investigate the clinical and molecular predictors of outcomes in adults with TP53-mutant ALL. Methods: We retrospectively studied 107 patients with TP53-m ALL treated at seven different academic centers in North America. Genetic profiling of pre-treatment bone marrow samples was performed with a comprehensive panel covering 147 myeloid and lymphoid genes. We also performed RNA-sequencing to identify fusions that define ALL subtypes. Single nucleotide polymorphism (SNP) array was used to define low hypodiploidy. Results: The median age at diagnosis was 59 years (range, 10-80), 42% were female, 70% White. 89% of pts had B-ALL while 11% had T-lineage ALL. 24% of pts were classified to have therapy-related ALL based on their history of exposure to genotoxic therapy for another cancer. 45% of pts had hypodiploid karyotype, 79% of whom were low-hypodiploid. 7% had hyperdiploid karyotype and 5% had BCR::ABL1. 11 pts had two different TP53 variants. 90% of TP53 variants involved the DNA binding domain. Most frequently observed co-occurring mutations involved CDKN2A (20%), NOTCH1 (12%) and RB1 (10%) genes. 71% of pts were treated with standard cytotoxic chemotherapy, while the remaining pts received newer antibody-based therapies (i.e., inotuzumab, blinatumomab) or venetoclax in first-line setting. 11% of pts received allogeneic hematopoietic cell transplant (HCT) in first complete remission (CR1) while 3% received HCT after relapse (CR2 or CR3). When patients with vs without low hypodiploidy were compared, we did not observe a significant difference in overall survival (OS) as outcomes were poor in both groups (median, 17 vs 19 months, p= 0.89). However, pts who had TP53 AF >0.5 had significantly worse OS when compared to pts with TP53 VAF <0.5 (13 vs 25 months, p= 0.03). Conclusions: TP53-m ALL is a very high-risk disease subtype and its dismal outcome is independent from presence of co-existing low hypodiploidy. Loss of heterozygosity, characterized by TP53 AF >0.5 is associated with even worse survival. New therapies are urgently needed to improve outcomes in this subset.

Background: Hypomethylating agent (HMA) and venetoclax (VEN) therapy is a standard of care frontline treatment of acute myeloid leukemia (AML) amongst patients (pts) ineligible for intensive therapy. Despite its convenient flat dose, oral nature, and static excretion irrespective of body weight (wt), VEN has a large, variable volume of distribution and extensive protein binding (Yang, Molecules, 2022). Body mass index (BMI) is a more accurate, albeit imperfect, indicator of body fat that has not been evaluated as an independent predictor of differential VEN exposures and clinical outcomes. We sought to evaluate this possibility amongst pts treated with frontline HMA+VEN in a multi-center, real-world, retrospective study. Methods: We conducted a multi-center, retrospective study through four US academic centers in the Consortium on Myeloid Malignancies and Neoplastic Diseases (COMMAND). 368 pts treated with frontline HMA+VEN from 6/2016-8/2023were evaluated based on BMI within 30 days of induction. Responses were defined by European LeukemiaNet (ELN) 2022 criteria. Pearson's chi-squared test and Wilcoxon rank-sum test were used for comparison between groups. The Kaplan-Meier method and multivariable Cox regression model were applied to overall survival (OS). Continuous variables were summarized as a median with interquartile range (IQR), and categorical variables were reported as a frequency (percentage). Results: The median age was 75 (IQR: 70-79) years, 58% were male, and 76% were white. 107 (29%) had a normal BMI of 18-25 kg/m2, 141 (38%) were overweight (BMI 25-30 kg/m2), and 120 (33%) were obese (BMI >30 kg/m2). There were no significant differences in baseline pt-, disease-, and treatment-specific factors when comparing pts with normal wt to BMI >25.The cohort was enriched for complex karyotype and TP53-mutated disease (27% and 32%, respectively), with 73% categorized as adverse risk by ELN 2022. There was no difference in 30-, 60-, and 90-day mortality rates (6-8%, 14-18%, 19-29%, respectively) by BMI group. Complete remission (CR/CRi) rate was 50% overall and was not impacted by BMI (41%, normal wt; 55%, overweight; 52%, obese) (p=0.10). Overall response rate (ORR) (CR/CRi/MLFS) was 59% overall and differed by BMI groups (50%, normal wt; 66%, overweight; 58%, obese) (p= 0.047). The median OS was 6.6 months for normal wt, 13.7 months for overweight, and 8.3 months for obese pts, and not significantly different when comparing normal to overweight (p=0.052) or obese pts (p=0.756). In multivariable analysis, the effect of BMI varied by the composite remission rate used. Overweight was borderline significantly associated with higher likelihood of achieving CR compared to normal wt (odds ratio [OR] 1.98, 95% confidence interval [CI] 0.99-4.03; p=.056), whereas obesity was not (OR 1.78, CI 0.86-3.74; p=.13). Other co-variates with a significant association with achieving CR included diagnosis of secondary AML (sAML) (OR 0.37, CI 0.18-0.74; p=.006) and presence of IDH (OR 2.81, CI 1.30-6.15; p=.009), ASXL (OR 0.39, CI 0.15-0.96; p=.046), TET2 (OR 2.43, CI 1.17-5.09; p=.02), and DNMT3A (OR 2.37, CI 1.19-4.78; p=.02) mutations. There was a trend towards higher likelihood of achieving CR/CRi for both overweight (OR 1.74, CI 0.92-3.32; p=.09) and obese pts (OR 1.88, CI 0.96-3.74; p=.07). Diagnosis of sAML and presence of TET2, ASXL, and DNMT3A mutations no longer had a significant association with achieving CR/CRi, while IDH mutations maintained an association (p=.01). None of these variables demonstrated a significant impact on ORR (inclusive of MLFS) except overweight (OR: 1.99, CI 1.06-3.80; p=.03) and sAML vs de novo (OR: 0.53, CI 0.29-0.99; p=.047). In multivariable logistic regression, higher ECOG score was associated with risk of early mortality within 60 (p=.01) and 90 (p=.01) days, but not 30 days. sAML vs de novo associated with higher 90-day mortality, presence of NPM and TP53 mutation associated with higher 30-day mortality, and cytogenetic risk associated with higher 60- and 90-day mortality. Conclusions: This multi-center, real-world study demonstrates that BMI may not have a linear effect on response to frontline HMA+VEN, with some indication of negative impact at both lower and higher BMI categories. However, additional dedicated studies are needed to determine if differences in BMI is associated with altered drug exposure as an explanation for these differences.

PURPOSEOn the basis of the results of the ZUMA-3 trial, brexucabtagene autoleucel (brexu-cel), a CD19-directed chimeric antigen receptor T-cell therapy, gained US Food and Drug Administration approval in October 2021 for adults with relapsed/refractory (R/R) B-cell ALL (B-ALL). We report outcomes of patients treated with brexu-cel as a standard therapy.METHODSWe developed a collaboration across 31 US centers to study adults with B-ALL who received brexu-cel outside the context of a clinical trial. Data were collected retrospectively from October 2021 to October 2023. Toxicities were graded per American Society for Transplantation and Cellular Therapy guidelines for cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS).RESULTSAt the time of data lock, 204 patients had undergone apheresis and 189 were infused. Median follow-up time was 11.4 months. Forty-two percent of patients received brexu-cel in morphologic remission and would have been ineligible for participation in ZUMA-3. After brexu-cel, 151 achieved complete remission (CR), of which 79% were measurable residual disease (MRD) negative remissions. Median progression-free survival (PFS) was 9.5 months and median overall survival was not reached. Grade 3-4 CRS or ICANS occurred in 11% and 31%, respectively. In multivariable analysis, patients receiving consolidative hematopoietic cell transplantation (HCT; hazard ratio, 0.34 [95% CI, 0.14 to 0.85]) after brexu-cel had superior PFS compared with those who did not receive any consolidation or maintenance therapy.CONCLUSIONSimilar to ZUMA-3, high rates of MRD-negative CR were observed after brexu-cel treatment for R/R B-ALL. The use of HCT as consolidation after brexu-cel resulted in improved PFS.

Introduction: The development of increasingly sensitive tests for the detection of measurable residual disease (MRD), such as multiparameter flow cytometry (MFC) and next-generation sequencing (NGS) assays, has changed clinical practice in acute lymphoblastic leukemia (ALL). IGH V(D)J-based NGS MRD is the most sensitive assay to predict relapse in patients (pts) with B-ALL (Short, Blood Adv 2022). However, data regarding the use of T-cell receptor (TR) NGS MRD in T-ALL are limited and recent reports from pediatric cohorts suggest that persistent TR MRD may not predict relapse in T-ALL (Roy, ASH 2023, abstract 2976). With limited options for the treatment of relapsed/refractory T-ALL, accurate prediction of high relapse risk may provide an opportunity for early intervention. In this study, we evaluated the prognostic utility of TRB/TRG NGS MRD and its correlation with MFC MRD in adult patients with T-ALL. Methods: We retrospectively evaluated the MRD data and clinical outcomes of precursor T (pre-T) and early T precursor (ETP) ALL patients treated at four academic centers in the US. MRD was evaluated using MFC in CLIA-certified labs at individual sites with a sensitivity of 10-4, and the clonoSEQ (Adaptive Technologies, lnc) NGS assay, with a sensitivity of 10-6. Pts were included if they had a trackable TR clone and NGS MRD remission assessment in at least one time point. The correlation between the percentage of MRD by MFC vs NGS was calculated with the Pearson correlation coefficient, using every available MRD assessment for T-ALL pts in complete remission. Relapse-free survival was stratified based on NGS MRD level at the time of post-induction and post-consolidation assays, and comparisons were made with the log-rank test. The positive predictive value (PPV) for relapse of NGS MRD was calculated for pts with MRD > 10-6 at the post-induction and post-consolidation period. Results: A total of 19 pts who met our inclusion criteria, with a median age of 30 years (range, 18-65). 9 pts (47%) had ETP-ALL, 10 pts had pre-T ALL. Pts had a trackable TRB/TRG clone in 76% of cases, with 66% having a trackable TRG clone and 38% having a trackable TRB clone. 10 pts (53%) were treated with a modified AALL0434 regimen as first line therapy, 6 pts (32%) were treated with CALGB10403, 1 pt (5%) was treated with hyperCVAD, 1 pt (5%) was treated with a BFM regimen, and 1 pt (5%) was treated with CALGB9511. Out of 11 T-ALL pts with MRD data available post-induction, 6 pts (55%) had detectable MRD by NGS and no detectable MRD by MFC. Out of 13 pts with available post-consolidation MRD data, 2 pts (15%) had undetectable MRD by both NGS and MFC and 9 pts (69%) had detectable MRD by NGS only. There were no pts with detectable MRD by MFC and undetectable MRD by NGS at either timepoint. A total of 64 MRD data points from 19 pts were available to evaluate MRD correlation by MFC vs NGS, for which the Pearson correlation coefficient showed a statistically significant linear correlation (p < 0.01). At post-induction, 9 pts had NGS MRD > 10-4 and 2 pts had NGS MRD < 10-4. With a median follow-up time of 19.8 months, pts with NGS MRD > 10-4 had a median RFS of 19.8 months and pts with NGS MRD < 10-4 had a median RFS of 14.8 months. The log-rank test comparing RFS between these two groups was not statistically significant (p= 0.18). Persistent NGS MRD at post-induction had a PPV for relapse of only 18%. At post-consolidation, 7 pts had NGS MRD > 10-4, 4 pts had NGS MRD < 10-4, and 2 pts had undetectable MRD by NGS. With a median follow-up time of 17.3 months, pts with NGS MRD > 10-4 had a median RFS of 15.3 months and pts with NGS MRD < 10-4 or undetectable had a median RFS of 20.6 months. The log-rank test comparing RFS between these two groups was not statistically significant (p= 0.6). Persistent NGS MRD at post-consolidation had a PPV for relapse of only 27%. Conclusion: Despite statistically significant linear correlation between MFC and NGS MRD testing, there were no RFS differences between pts with NGS MRD > 10-4 vs NGS MRD < 10-4. All patients had persistent NGS MRD post-induction, which is markedly lower than the reported 20-25% NGS undetectable MRD rate in B-ALL post-induction. Persistent NGS MRD has low PPV for relapse in T-ALL, which limits its utility in clinical decision making for this population.

Introduction: Brexucabtagene Autoleucel (brexu-cel) is the first CD19-targeting chimeric antigen receptor (CD19.CAR) T-cell therapy approved for the treatment of relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL) in adult (≥18 yo) patients (pts) based on results from the ZUMA-3 trial. However, data on the safety and efficacy of CAR-T cells in older pts (≥60 yo) remains limited, with only 8 pts >65 yo enrolled in the ZUMA-3 trial. We evaluated the treatment characteristics and outcomes with use of brexu-cel amongst patients ≥60 yo in the Real-World Outcomes Collaborative for CAR-T in ALL (ROCCA) consortium database. Methodology: ROCCA is a consortium of over 30 U.S.-based institutions with a database of adult pts with B-ALL who received brexu-cel as standard of care therapy. We identified pts ≥60 yo and further stratified them into two cohorts: 60-69 yo and ≥70 yo. Outcomes of interest included OS, PFS, ORR, and toxicities (CRS and ICANS). Both OS and PFS were calculated from the day of brexu-cel infusion. Response assessment occurred on day +28, and MRD evaluation was per institutional practices. CRS and ICANS were graded according to the American Society for Transplantation and Cellular Therapy criteria. Results: Of 280 brexu-cel recipients in the ROCCA database, 73 (26%) were ≥60 yo, of which 58 (79%) were between 60-69 yo and 15 (21%) were ≥70 yo. Among pts ≥60 yo, the median age at infusion was 65 (range 60-81). Pts were heavily pretreated with a median of 3 prior lines of therapy (range 2-9). Prior therapies included: allogeneic HSCT (38%), inotuzumab ozogamicin (41%), and blinatumomab (62%). Forty pts (55%) had Ph-negative B-ALL, 24 (33%) had Ph+ B-ALL and 9 (12%) had Ph-like B-ALL. When grouped by HCT-CI equal to 0, 1-2 or ≥3, a higher proportion of pts ≥60 yo had HCT-CI ≥3 (19% vs. 7% in <60 yo; p=0.004). Pre-apheresis, 33 pts (45%) had active disease (>5% marrow blasts or extramedullary disease), 34 (47%) were in CR (of whom 14 were MRD-negative) and 6 had unknown disease status. Following brexu-cel, 43 (59%) achieved MRD-negative CR, 20 (27%) had MRD + or CR with unknown MRD status, 6 (8%) had refractory disease and 5 had no disease evaluation available. The ORR was similar between pts 60-69 and ≥70 yo (MRD-negative CR rate: 58% vs 61%, r/r to brexu-cel: 9% vs 6%) and was comparable to pts <60 yo (MRD-negative CR 66%; r/r disease of 9%). The rate of all grade ICANS was higher in pts ≥70 (77%) than in pts 60-69 (47%) or pts <60 (49%), with grade 1-2 ICANS occurring at a significantly higher rate in pts ≥70 (44% vs. 20% in 60-69 and 20% in <60, p=0.049). Grade 3-4 ICANS were similar between the groups: 33%, 27% and 29% in the ≥70, 60-69, and <60 groups, respectively. Conversely, rates of CRS were similar across age groups (80-84%). There was no statistically significant difference in the rate of grade 3-4 CRS which was 17% in pts ≥70, 4% in pts 60-69, and 11% in pts <60 yo. With a median follow-up of 332 days (range 8-936 days) from infusion, pts ≥60 yo had a median PFS of 395 days compared to 547 days in pts <60 yo. Median PFS was lower in the ³70 yo (231 days) compared to 677 in the 60-69 yo cohort. No statistically significant difference was found between the <60 and ≥60groups in 6- and 12-month PFS rates (6 months PFS: 66% vs 64%, p=0.77 and 12 months PFS: 57% vs 57%, p=1.00). When pts ≥60 yo were stratified by age, pts ≥70 yo had similar 6-month PFS compared to other age groups but significantly lower 12-month PFS (38%; vs. 64% in pts 60-69and 57% in pts <60, p=0.001). Median OS was not reached in any of the age groups, and there was no statistically significant difference in 6-month OS (72% in ≥ 70 vs. 82% in the 60-69 vs. 82% in <60, p=0.14) or 12-months OS (61% in ≥ 70 vs. 69% in 60-69 vs. 73% in <60, p=0.18). Conclusion: This is the largest study to date of older B-ALL pts receiving CAR-T cells. We observed that older pts, particularly those aged 60-69, have similar outcomes to younger pts. However, pts ≥70 yo had lower median and 12-month PFS when compared to younger patients. Additionally, pts ≥70 yo had higher rates of grades 1-2 ICANS. An important limitation of this analysis is the potential selection bias among clinicians when selecting older patients for this treatment. Longer follow-up, including inclusion of additional pts ≥70 yo is needed to confirm these results, and further studies are needed to identify the optimal approach for use of CAR T-cell therapy in patients in this age group.

Introduction: Chimeric Antigen Receptor (CAR)- T cell therapy has revolutionized the treatment of hematologic malignancies. However, access to CAR-T therapy remains limited, especially for underserved populations. We hypothesize that disparities in age, gender, race, and insurance type affect access and progression through key stages of CAR-T therapy-referral, evaluation, and infusion of CAR- T cells. These disparities contribute to inequities in the utilization of CAR-T therapy. Method: This retrospective study analyzed data from July 2019 to June 2022, incorporating records from the North Carolina Central Cancer Registry (NCCCR) and Duke Cancer Institute. The study focused on adults aged 19-79 with lymphoma or multiple myeloma residing in 67 North Carolina counties, which are designated as Duke's primary catchment area. Cohort 1 comprised NCCCR-Eligible patients-those identified in the NCCCR dataset as eligible for CAR-T infusion. Cohort 2 included Duke Referred patients, further divided into: 2A) Referral Only-patients who were referred but did not receive an appointment; 2B)Appointment without infusion-patients who had an appointment but did not receive CAR-T therapy; and 2C) CAR-T -patients who underwent CAR-T infusion. Statistical analyses included chi-square tests, ANOVA or Wilcoxon Signed Rank tests, and logistic regression. Referrals to other centers within the DCI catchment and out-of-state counties were excluded from the study. Results: NCCCR eligible vs. Duke Referred (Cohort 1 vs 2): Comparing the NCCCR cohort with CAR-T candidates referred to Duke, Duke referrals are younger median 64 [22-79] versus 66 years [19-79] in NCCCR, p = 0.004) and with fewer Caucasian/White patients (60% DCI vs. 71% NCCCR) and more Black or African American (30% DCI vs. 24% NCCCR). Private insurance is higher at DCI (50% vs. 31% NCCCR). Both cohorts are predominantly in metropolitan areas (81% DCI vs. 78% NCCCR, p < 0.001) and Medicare was less common than in NCCCR (40%, vs. 53%, p<0.001). DCI has a higher median income ($67,000 vs. $58,646, p < 0.001) and a lower social vulnerability index (0.61 vs. 0.66, p < 0.001). Referral Only vs Appointment without Infusion (Cohort 2A vs. 2B): Analysis of the referral-only cohort versus those who attended an initial evaluation appointment for CAR-T revealed significant sociodemographic differences. African Americans were more prevalent among the referral-only group (37% vs. 30%, p = 0.004) and had lower odds of attending initial evaluation appointments (OR = 0.55, 95% CI [0.35-0.87], p = 0.010). Univariate analysis indicated that a lower proportion of the referral-only group had private insurance (44% vs. 49%, p = 0.007) and Medicare coverage (40% vs. 44%, p = 0.007). However, these differences did not persist in multivariate analysis (OR = 0.78, 95% CI [0.49-1.23], p = 0.3 for Medicare). Non-private, non-Medicare insurance showed a trend towards lower attendance at initial appointments (OR = 0.35, 95% CI [0.14-1.03], p = 0.040), but this trend was not significant, likely due to the small sample size. The median time to appointment was 20 days (range 1-253). Age, sex, RUCA classification, income, and social vulnerability index did not show significant effects (p > 0.1). Appointment without Infusion vs CAR-T (Cohort 2B vs. 2C): Comparison of patients evaluated without infusion versus CAR-T recipients revealed higher odds of proceeding to CAR-T for males (OR = 2.68, 95% CI [1.63-4.56], p < 0.001) and Black or African American patients (OR = 1.87, 95% CI [1.06-3.23], p = 0.027). The median time to CAR-T was 141 days (range 41-1,248). No significant differences were observed in age, insurance type, RUCA classification, income, or social vulnerability index. Conclusion: Barriers to CAR-T therapy access at Duke appear to vary by stage. Initially, African American race and non-private insurance are linked to lower attendance at evaluation appointments post-referral. After evaluation, female gender and African American race are associated with a lower likelihood of proceeding to CAR-T infusion, highlighting significant gender and racial disparities. Further research is needed to determine if these disparities are due to demographic, socioeconomic, or healthcare system factors. Tailored interventions and collaborations with community partners and patient navigators are crucial for addressing these disparities and ensuring equitable access to CAR-T therapy.

Abstract Background: The Proto-oncogenic PIMs family are nuclear and cytoplasmic Ser/Thr kinases (PIM1, PIM2, and PIM3) that are constitutively active and play a vital role in proliferation and survival in Multiple Myeloma (MM). Activated PIM1 kinase can induce progression of the cell cycle, inhibition of apoptosis, and modulation of other signal transduction pathways. Methods: BLX-0631 and a few analogs evaluated against a panel of MM cell lines (EJM, IM-9, L-363, LP-1, MM-1R, MM.1S, MOLP-2, NCI-H929, OPM-2, RPMI8226 and U-266) and primary MM patient samples by CellTiter-Glo® (CTG) assays. Cellular apoptosis, Cell cycle analysis, Flow Cytometry, and bone marrow microenvironment experiments on the most sensitive cells were performed. PIM1 and downstream targets by western blot, cell migration, and invasion on our lead PIM1 inhibitor BLX-0631 along with, kinome selectivity, ADME-Tox, PK, and in vivo MM.1S efficacy experiments were conducted. Results: The application of our empirical MolecuLernTM fragment library, PIM1 crystal structure, scaffold hopping, and the enumeration features of MolecuLernTM in combination with 3, 6, and 7-group analysis on pyridazine, lead to a synthesizable potential new lead series, representing Med Chem tractability and developable characteristics. Further, the consensus scoring, binding energies, and MolecuLern tractability filters were applied and led to the discovery of the BLX-0631 series that inhibits the PIM1 kinase. The active compounds, with their binding modes and lead optimization strategies, lead to the synthesis and testing of over 60 novel entities as PIM1 kinase inhibitors. Thus, based on our previous chemotype series and scaffold hopping method, the impact of changing the 3, 6, and 7 positions, while retaining the pyridazine core led to the discovery of BLX-0631 and its series of compounds exhibiting <5 nM potency. BLX-0631 in CTG assay demonstrated 100% cell growth inhibition across all MM cell lines tested. The lead compound BLX-0631 is a very potent inhibitor with an IC50 of 5.0/17/5.0 nM when tested against PIM1, PIM2, and PIM3 kinases respectively, and selective against a panel of 468 kinase panels. Dosing through IV and PO delivery routes, formulations, salt forms of BLX-0631 in mice, PK properties along with ADME-Tox, P450, and hERG results will be presented. In vivo MM.1S mouse xenograft models of BLX-0631 at 15, 30 and 45 mg/Kg, p.o, QD demonstrated TGI of 16.28%, 31.81% & 35.16% dose-dependently. Conclusions: The present study demonstrates that PIM1 plays a vital role in the proliferation and survival of Multiple Myeloma. BLX-0631 induces full inhibition of all MM cell lines, suppresses cancer cell proliferation in vitro, and exhibits promising efficacy in MM tumor models. BLX-0631, a nominated IND candidate can serve as a novel targeted agent for treating Multiple Myeloma patients. Citation Format: Zhaoang li, Chenyu Lin, David J. Bearss, Hariprasad Vankayalapati. Development of highly selective, potent, orally available PIM1 inhibitor BLX0631 shows a therapeutics potential in multiple myeloma models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4587.

BackgroundThe KRAS G12C inhibitor sotorasib was approved for the treatment of advanced NSCLC in the second line or later based on the CodeBreaK100 trial. However, data on the real-world efficacy and safety of sotorasib, as well as its optimal dose, remain limited.MethodsPatients treated with sotorasib for NSCLC through the Veterans Health Administration (VHA) were retrospectively identified from the Corporate Data Warehouse. Survival, response, and toxicity data were obtained from chart review.ResultsAmong the 128 patients treated with sotorasib through the VHA, objective response rate was 34%, progression-free survival (PFS) 6.0 months, and overall survival (OS) 12.0 months. Similar PFS was observed among the 16 patients who received frontline sotorasib without any prior systemic therapy for NSCLC. Toxicity leading to sotorasib interruption or dose reduction occurred in 37% of patients, while sotorasib discontinuation for toxicity occurred in 25%. Notably, sotorasib dose reduction was associated with significantly improved PFS and OS.DiscussionIn this real-world study, the observed efficacy of sotorasib was similar to the results of CodeBreaK100. Patients who received frontline sotorasib had similar PFS to our overall cohort, suggesting that first-line sotorasib monotherapy may benefit patients who are not eligible for chemotherapy. Toxicities leading to sotorasib interruption, dose reduction, or discontinuation were common. Sotorasib dose reduction was associated with improved survival, suggesting that sotorasib dose reduction may not compromise efficacy.

8581 Background: KRAS mutations have historically carried a poor prognosis in NSCLC. The most common variant, G12C, had similar survival compared to non-G12C variants. However, new KRAS G12C inhibitors have since been approved. This national VHA study evaluates the outcomes of KRAS-mutated advanced NSCLC by KRAS subtype in the era of KRAS G12C inhibitors. Methods: Patients with unresectable or metastatic NSCLC and a KRAS mutation detected between 2021-2022 were identified from the VA National Precision Oncology Program database. Analysis utilized Fisher’s exact test, logistic regression, and Cox regression. Results: 841 patients across 107 VA medical centers met search criteria. The median age was 73, and 95% were male. 21% were non-Hispanic black, 70% non-Hispanic white, and 2.5% Hispanic. 4% were never smokers. The most common KRAS mutations were G12C (35%), G12V (18%), G12D (13%), G12A (6%), Q61H (4%), and G13D (4%). The most common co-mutations to KRAS were TP53 (54%), STK11 (28%), KEAP1 (16%), and BRAF (3%). KEAP1 mutations more frequently co-occurred with KRAS Q61H (p=0.048), while BRAF mutations were more commonly seen with KRAS G13D (p=0.02) and G13C (p=0.01). In univariable analysis of overall survival (OS), KRAS G12C had a favorable OS compared to all non-G12C variants (HR 0.77, 95% CI 0.64-0.93, p=0.006). Specifically, KRAS G12D (HR 1.35, CI 1.03-1.76, p=0.03) and G12V (HR 1.42, CI 1.10-1.81, p=0.006) had significantly worse OS compared to G12C. Higher PDL1 TPS (HR 0.997, CI 0.995-0.999, p=0.02) and higher TMB (HR 0.96, CI 0.95-0.98, p<0.0001) had better OS, while older age (HR 1.02, CI 1.01-1.03, p=0.004) and co-mutations in KEAP1 (HR 1.60, CI 1.28-1.97, p<0.0001) and STK11 (HR 1.57, CI 1.31-1.88, p<0.0001) had worse OS. Social deprivation index (SDI, calculated by zip code), race/ethnicity, rural residence, and other co-mutations did not affect survival. In multivariable Cox regression, age (HR 1.02, CI 1.003-1.03), KRAS G12C (HR 0.74, CI 0.58-0.93), TMB (HR 0.97, CI 0.95-0.98), and STK11 (HR 1.62, CI 1.23-2.12) retained their association, while KEAP1 and PDL1 were no longer significant. Use of sotorasib had a borderline association with improved survival in univariable analysis (HR 0.74, CI 0.52-1.02). After adjusting for sotorasib in the multivariable model, the association of G12C with OS was no longer significant. In KRAS G12C NSCLC receiving at least 2 lines of therapy (n=90), the likelihood of receiving sotorasib did not differ by age, SDI, gender, race/ethnicity, or rural vs. urban residence. Only a history of economic instability (by ICD10 code) was associated with a lower likelihood of getting sotorasib (OR 0.22, 95% CI 0.03-0.91). Conclusions: In this cohort, KRAS G12C appears to confer a favorable prognosis compared to non-G12C variants, which may be explained in part by the adoption of sotorasib.

Abstract Background: The use of novel, potent targeted therapies in prostate cancers has led to the development of highly aggressive variant cancers, including neuroendocrine prostate cancer (NEPC). Gene amplification of N-MYC and C-MYC oncogenes leads to its overexpression in NEPC and mCRPC patients, highly prevalent in these lethal subtypes of cancers detected in 2% of all Prostate Cancers (PCa) and over 10-17% of mCRPC patients. N-MYC is a transcriptional target of CDK9, which acts as an oncogenic driver sufficient to transform human-derived prostate cancer to take on NEPC phenotypic changes resulting in a more aggressive disease identified in late-stage human PCa patients. Additionally, N-MYC and C-MYC are required for tumor drug resistance, and their downregulation through CDK9 inhibition lowers tumor growth. Our efforts have demonstrated that targeting both N-MYC and C-MYC as a driver of NEPC and mCRPC with highly selective CDK9 inhibitor BLX-3030 is a viable approach for therapeutic intervention of mCRPC and NEPC. Materials and Methods: Our empirical data-driven AI/ML MolecuLernTM fragment library, workflows, LigEdit design strategies, and hit2-lead optimization methods are employed. In vitro experiments include kinase glo, cell titer glo, selectivity profiler, ADME-Tox, FACS/apoptosis, cell migration, live cell imaging, immunofluorescent, western blot, combination studies and in vivo experiments including PK, prostate tumor models, 7-day tox, BLX-3030 non (GMP) scaleup and safety pharmacology experiments conducted. Results: We synthesized a series of novel small molecule CDK9 inhibitors that reversibly bind to CDK9, competitively block the ATP site with an IC50 of 1.06 nM, and elicit pharmacological responses in N-MYC, C-MYC, and other prostate cancer cells in vitro and in vivo. We studied the CDK9 N-MYC expression detected in PC-3, DU-145, LNCaP, and in LASCPC-01, NCI-H660, and 22RV1 cell lines. BLX-3030 exhibited potent cellular efficacy with an IC50 of 22 to 590 nM in PC cell lines and in N-MYC expressed cells had an activity of 76, 470, and 132 nM respectively, and reduced pCDK9, C-MYC, Mcl-1, N-MYC and its downstream RNA Pol II (Ser-2) and pAR (Ser-81) dose-dependently. BLX-3030 exhibits in vivo antitumor activity in LASCPC-01, 22RV1, and C4-2 prostate cancer mouse models. Several ADME-Tox, MTD, dose range finding, hERG and other in vivo safety pharmacology experiments have advanced BLX-3030 to the IND enabling studies. Conclusions: BLX-3030 is currently being investigated in non-clinical toxicology, toxicokinetic, and core battery of safety pharmacology studies including the assessment of effects on cardiovascular, central nervous, and respiratory systems. Citation Format: Zhaoang li, Chenyu Lin, Kyle Medley, Hariprasad Vankayalapati, David J. Bearss. BLX-3030, a potent, selective, orally available small molecule CDK9 inhibitor for aggressive variant prostate cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4649.

e13707 Background: Excessively stringent clinical trial eligibility criteria may hinder trial accrual, differentially exclude racial-ethnic minority groups, and limit generalizability. This study reviewed the association between trial accrual and concordance of eligibility criteria with known drug safety data in DLBCL clinical trials. Methods: Eligibility criteria and accrual of completed phase II/III clinical trials for DLBCL that opened in the US between 2010-2020 were abstracted from ClinicalTrials.gov. Trials missing posted results or studying cellular therapy / transplant were excluded. Concordance with known safety data was assessed by comparing study eligibility criteria for QTc, renal, hepatic, and cardiac function to FDA labels and phase I safety signals of study drugs. Excessively strict discordant criteria (ExSDC) were defined as eligibility criteria without supporting safety signals. Logistic regression +/- dispersion was used for analysis. Results: 58 trials met criteria for inclusion, accruing 6,232 participants. 88% of studies involved a non-FDA-approved agent, 74% were multicenter, 55% were industry sponsored, 66% only accrued in the US, and 86% were phase II. Eligibility criteria were highly variable (Table). Discordance of renal, hepatic, cardiac function, and QTc criteria from known safety data occurred in 31%, 26%, 41%, and 29% of studies, respectively. Race and ethnicity data were not reported in 22% and 45% of studies, respectively. Trials after 2015 were more likely to report race (p=0.04) and ethnicity (p=0.01). In a multivariable model adjusted for international study sites, greater number of ExSDC was associated with a lower proportion of black patients in the trial (OR 0.45, CI 0.29-0.71, p=0.001). ExSDC in cardiac function were most associated with reduced accrual of this minority group (OR 0.17, CI 0.05-0.58, p=0.007). 11 studies (19%) had early termination for lack of accrual (ETLA). In multivariable analysis, greater number of ExSDC was independently associated with ETLA (OR 3.53, CI 1.45-8.64, p=0.006), while multicenter status protected against ETLA (OR 0.05, CI 0.01-0.31, p=0.002). Industry sponsor and concordance of cardiac criteria protected against ETLA in univariable analysis only. Other eligibility criteria were not associated. Conclusions: Eligibility criteria in DLBCL trials varied widely and were often discordant with known safety data. Higher number of ExSDC was associated with lower accrual of black patients and higher risk of ETLA. Optimizing concordance of eligibility criteria with safety data may improve trial accrual and diversity. [Table: see text]

Myelofibrosis (MF) in the chronic phase is a challenging disease entity to treat, and conventional treatment options are geared towards symptom palliation. In this prospective, multicenter, phase II trial, 21 patients with myelofibrosis (18 chronic-phase, 2 accelerated-phase, 1 blast-phase) were treated with a 10-day schedule of subcutaneous decitabine at 0.3 mg/kg/day. The overall response rate was 33% (95% CI, 15-57), primarily manifested as an improvement in cytopenias. The median duration of response was 7 months (range, 3-44). A high IPSS risk score, high baseline fetal hemoglobin level, and sustained decreases in circulating CD34+ cell counts were associated with response to decitabine. All patients experienced at least one grade 3 or 4 cytopenia. Non-hematologic toxicities were less frequent, with fatigue, anorexia, and hypocalcemia being the most common. Given the lack of effective therapies in myelofibrosis with severe cytopenias, this study supports further investigation into the use of hypomethylating agents as single agents or in combination therapies. NCT00095784.