L'invention concerne, selon un mode de realisation, des methodes et des utilisations therapeutiques d'inhibiteurs de la tyrosine kinase de Bruton (BTK) pour le traitement du cancer, de l'inflammation, des affections immunes et auto-immunes, et pour la prophylaxie en matiere de transplantation, fondees sur les taux d'occupation et/ou de resynthese de BTK, dans diverses maladies, pour les lymphocytes B, dans les compartiments tissulaires, dont la moelle osseuse et les ganglions lymphatiques. L'invention concerne, selon un mode de realisation, la posologie pour un inhibiteur de BTK en vue du traitement du cancer, de l'inflammation, des affections immunes et auto-immunes, dont les dermatoses, et pour la prophylaxie en matiere de transplantation, posologie fondee sur les taux d'occupations et/ou de resynthese de BTK, dans diverses maladies, pour les lymphocytes B, dans les compartiments tissulaires, dont la moelle osseuse et les ganglions lymphatiques.

BACKGROUND Irreversible inhibition of Bruton's tyrosine kinase (BTK) by ibrutinib represents an important therapeutic advance for the treatment of chronic lymphocytic leukemia (CLL). However, ibrutinib also irreversibly inhibits alternative kinase targets, which potentially compromises its therapeutic index. Acalabrutinib (ACP-196) is a more selective, irreversible BTK inhibitor that is specifically designed to improve on the safety and efficacy of first-generation BTK inhibitors. METHODS In this uncontrolled, phase 1-2, multicenter study, we administered oral acalabrutinib to 61 patients who had relapsed CLL to assess the safety, efficacy, pharmacokinetics, and pharmacodynamics of acalabrutinib. Patients were treated with acalabrutinib at a dose of 100 to 400 mg once daily in the dose-escalation (phase 1) portion of the study and 100 mg twice daily in the expansion (phase 2) portion. RESULTS The median age of the patients was 62 years, and patients had received a median of three previous therapies for CLL; 31% had chromosome 17p13.1 deletion, and 75% had unmutated immunoglobulin heavy-chain variable genes. No dose-limiting toxic effects occurred during the dose-escalation portion of the study. The most common adverse events observed were headache (in 43% of the patients), diarrhea (in 39%), and increased weight (in 26%). Most adverse events were of grade 1 or 2. At a median follow-up of 14.3 months, the overall response rate was 95%, including 85% with a partial response and 10% with a partial response with lymphocytosis; the remaining 5% of patients had stable disease. Among patients with chromosome 17p13.1 deletion, the overall response rate was 100%. No cases of Richter's transformation (CLL that has evolved into large-cell lymphoma) and only one case of CLL progression have occurred. CONCLUSIONS In this study, the selective BTK inhibitor acalabrutinib had promising safety and efficacy profiles in patients with relapsed CLL, including those with chromosome 17p13.1 deletion. (Funded by the Acerta Pharma and others; ClinicalTrials.gov number, NCT02029443.).

La presente invention concerne des combinaisons therapeutiques d'un inhibiteur de la phosphoinositide 3-kinase (PI3K), comprenant des inhibiteurs de la PI3K selectifs pour les isoformes γ and δ et selectifs pour les isoformes a la fois γ and δ (PI3K-γ, δ, PI3K-γ et PI3K-δ), un inhibiteur de la kinase Janus-2 (JAK-2), un inhibiteur de la kinase 4/6 dependante des cyclines (CDK4/6), et/ou un inhibiteur de la tyrosine kinase de Bruton (BTK). Selon certains modes de realisation, l'invention concerne des combinaisons therapeutiques d'un inhibiteur de la kinase 4/6 dependante des cyclines (CDK4/6) et d'un inhibiteur de la BTK, d'un inhibiteur de la PI3K-δ et d'un inhibiteur de la BTK, d'un d'inhibiteur de la JAK -2 et de la BTK, et d'un inhibiteur de la JAK -2, de la PI3K-δ et de la BTK.

La presente invention concerne des compositions therapeutiques et des procedes d'utilisation des compositions, comprenant des combinaisons d'un inhibiteur de tyrosine kinase de Bruton (BTK), d'un inhibiteur de phosphoinositide 3-kinase (PI3K), comprenant des inhibiteurs de PI3K selectifs pour les isoformes γ et δ et selectifs pour les deux isoformes γ et δ (PI3K-γ,δ, PI3K-γ, et PI3K-δ,) un inhibiteur de mort programmee 1 (PD-1) ou de ligand de mort programmee 1 (PD-L1), et/ou d'un inhibiteur de Janus kinase-2 (JAK-2). Dans certains modes de realisation, la presente invention comprend des procedes therapeutiques d'utilisation d'un anticorps monoclonal de PD-1 et d'un inhibiteur de BTK. Dans d'autres modes de realisation, la presente invention comprend des procedes therapeutiques d'utilisation d'un anticorps monoclonal de PD-L1 et d'un inhibiteur de BTK. Dans d'autres modes de realisation, la presente invention comprend des procedes therapeutiques d'utilisation d'un inhibiteur de PD-1, d'un inhibiteur de BTK, et d'un inhibiteur de PI3K-δ. Dans d'autres modes de realisation, la presente invention comprend des procedes therapeutiques d'utilisation d'un inhibiteur de PD-L1, d'un inhibiteur de BTK, et d'un inhibiteur de PI3K-δ.

Introduction: The BTK inhibitor, ibrutinib is FDA-approved in MCL and CLL, with activity in the majority of CD20+ B-cell malignancies. As rituximab-combination chemotherapy is today’s standard of care in CD20+ B-cell malignancies, we previously investigated and determined ibrutinib antagonizes rituximab-dependent NK-cell mediated cytotoxicity (ADCC) due to ibrutinib’s secondary irreversible binding to interleukin-2 inducible tyrosine kinase (ITK) which is required for FcR-stimulated NK cell function including calcium mobilization, granule release, and overall ADCC. We hypothesized that BTK inhibitors, BTK-InhA (ACP-196), BTK-InhB (BGB-3111) and BTK-InhC (undisclosed), each with lower ITK binding, may preserve NK cell function and therefore synergize rather than antagonize rituximab.

BackgroundPatients with relapsed chronic lymphocytic leukemia (CLL) who have clinically significant coexisting medical conditions are less able to undergo standard chemotherapy. Effective therapies with acceptable side-effect profiles are needed for this patient population.MethodsIn this multicenter, randomized, double-blind, placebo-controlled, phase 3 study, we assessed the efficacy and safety of idelalisib, an oral inhibitor of the delta isoform of phosphatidylinositol 3-kinase, in combination with rituximab versus rituximab plus placebo. We randomly assigned 220 patients with decreased renal function, previous therapy-induced myelosuppression, or major coexisting illnesses to receive rituximab and either idelalisib (at a dose of 150 mg) or placebo twice daily. The primary end point was progression-free survival. At the first prespecified interim analysis, the study was stopped early on the recommendation of the data and safety monitoring board owing to overwhelming efficacy.ResultsThe median progression-free survival was 5.5 months in the placebo group and was not reached in the idelalisib group (hazard ratio for progression or death in the idelalisib group, 0.15; P<0.001). Patients receiving idelalisib versus those receiving placebo had improved rates of overall response (81% vs. 13%; odds ratio, 29.92; P<0.001) and overall survival at 12 months (92% vs. 80%; hazard ratio for death, 0.28; P=0.02). Serious adverse events occurred in 40% of the patients receiving idelalisib and rituximab and in 35% of those receiving placebo and rituximab.ConclusionsThe combination of idelalisib and rituximab, as compared with placebo and rituximab, significantly improved progression-free survival, response rate, and overall survival among patients with relapsed CLL who were less able to undergo chemotherapy. (Funded by Gilead; ClinicalTrials.gov number, NCT01539512.)A placebo-controlled study of idelalisib in patients with relapsed chronic lymphocytic leukemia who were receiving rituximab was stopped early because of significant improvement in rates of response, progression-free survival, and overall survival with idelalisib. Chronic lymphocytic leukemia (CLL) is the most prevalent leukemia among adults. Standard treatments include combinations of purine analogues, alkylating agents, and monoclonal antibodies. In younger patients without major coexisting illnesses, these regimens can provide high response rates of durable length but have substantial toxic effects. As a result, these treatments often have unacceptable side effects in older patients and those with coexisting illnesses.(1) Patients with relapsed CLL often have limited options because of the development of resistance to, or persisting toxic effects of, previous therapies. This is particularly true for elderly patients and those with coexisting illnesses.(2) For these patients, ...

In a phase 1 trial, idelalisib (GS-1101, CAL-101), a selective inhibitor of the lipid kinase PI3Kδ, was evaluated in 54 patients with relapsed/refractory chronic lymphocytic leukemia (CLL) with adverse characteristics including bulky lymphadenopathy (80%), extensive prior therapy (median 5 [range 2-14] prior regimens), treatment-refractory disease (70%), unmutated IGHV (91%), and del17p and/or TP53 mutations (24%). Patients were treated at 6 dose levels of oral idelalisib (range 50-350 mg once or twice daily) and remained on continuous therapy while deriving clinical benefit. Idelalisib-mediated inhibition of PI3Kδ led to abrogation of Akt phosphorylation in patient CLL cells and significantly reduced serum levels of CLL-related chemokines. The most commonly observed grade ≥3 adverse events were pneumonia (20%), neutropenic fever (11%), and diarrhea (6%). Idelalisib treatment resulted in nodal responses in 81% of patients. The overall response rate was 72%, with 39% of patients meeting the criteria for partial response per IWCLL 2008 and 33% meeting the recently updated criteria of PR with treatment-induced lymphocytosis.(1,2) The median progression-free survival for all patients was 15.8 months. This study demonstrates the clinical utility of inhibiting the PI3Kδ pathway with idelalisib. Our findings support the further development of idelalisib in patients with CLL. These trials were registered at clinicaltrials.gov as #NCT00710528 and #NCT01090414.

BACKGROUNDPhosphatidylinositol-3-kinase delta (PI3Kδ) mediates B-cell receptor signaling and microenvironmental support signals that promote the growth and survival of malignant B lymphocytes. In a phase 1 study, idelalisib, an orally active selective PI3Kδ inhibitor, showed antitumor activity in patients with previously treated indolent non-Hodgkin's lymphomas.METHODSIn this single-group, open-label, phase 2 study, 125 patients with indolent non-Hodgkin's lymphomas who had not had a response to rituximab and an alkylating agent or had had a relapse within 6 months after receipt of those therapies were administered idelalisib, 150 mg twice daily, until the disease progressed or the patient withdrew from the study. The primary end point was the overall rate of response; secondary end points included the duration of response, progression-free survival, and safety.RESULTSThe median age of the patients was 64 years (range, 33 to 87); patients had received a median of four prior therapies (range, 2 to 12). Subtypes of indolent non-Hodgkin's lymphoma included follicular lymphoma (72 patients), small lymphocytic lymphoma (28), marginal-zone lymphoma (15), and lymphoplasmacytic lymphoma with or without Waldenström's macroglobulinemia (10). The response rate was 57% (71 of 125 patients), with 6% meeting the criteria for a complete response. The median time to a response was 1.9 months, the median duration of response was 12.5 months, and the median progression-free survival was 11 months. Similar response rates were observed across all subtypes of indolent non-Hodgkin's lymphoma, though the numbers were small for some categories. The most common adverse events of grade 3 or higher were neutropenia (in 27% of the patients), elevations in aminotransferase levels (in 13%), diarrhea (in 13%), and pneumonia (in 7%).CONCLUSIONSIn this single-group study, idelalisib showed antitumor activity with an acceptable safety profile in patients with indolent non-Hodgkin's lymphoma who had received extensive prior treatment. (Funded by Gilead Sciences and others; ClinicalTrials.gov number, NCT01282424.).

GS-1101 (CAL-101) is an oral PI3Kδ-specific inhibitor that has shown preclinical and clinical activity in non-Hodgkin lymphoma and chronic lymphocytic leukemia. To investigate the potential role of PI3Kδ in Hodgkin lymphoma (HL), we screened 5 HL cell lines and primary samples from patients with HL for PI3Kδ isoform expression and constitutive PI3K pathway activation. Inhibition of PI3Kδ by GS-1101 resulted in the inhibition of Akt phosphorylation. Cocultures with stroma cells induced Akt activation in HL cells, and this effect was blocked by GS-1101. Conversely, production of the stroma-stimulating chemokine, CCL5, by HL cells was reduced by GS-1101. GS-1101 also induced dose-dependent apoptosis of HL cells at 48 hours. Reductions in cell viability and apoptosis were enhanced when combining GS-1101 with the mTOR inhibitor everolimus. Our findings suggest that excessive PI3Kδ activity is characteristic in HL and support clinical evaluation of GS-1101, alone and in combination, as targeted therapy for HL.

6518^ Background: PI3Kδ is expressed in cells of hematopoietic origin where it regulates the survival and proliferation of malignant B-cells. GS-1101 is an orally bioavailable, small-molecule inhibitor that selectively targets PI3Kδ and is highly active in patients with hematologic malignancies. Methods: This Phase 1/2 study evaluated repeated 28-day cycles of GS‑1101 in combination with ofatumumab. GS-1101 (150mg BID) was co-administered with a total of 12 infusions of ofatumumab over 24 weeks (300mg initial dose either on Day 1 or Day 2 (relative to the first dose of GS-1101), followed 1 week later by 1,000mg weekly for 7 doses, followed 4 weeks later by 1,000mg every 4 weeks for 4 doses). Thereafter, each subjects received single-agent GS‑1101 as long as the subject was benefitting. Results: Accrual is complete with 21 subjects enrolled and 11 evaluable. Six subjects started ofatumumab treatment on Day 1 and 5 on Day 2. Median [range] age was 63 [54‑76] years. The majority (9/11; 82%) of patients had bulky adenopathy. The median [range] number of prior therapies was 3 [1‑6], including prior exposure to alkylating agents (10/11; 90%), rituximab (9/11; 82%), purine analogs (8/11; 72%), alemtuzumab (3/11; 28%) and/or ofatumumab (2/11;18%). At the data cutoff, the median [range] treatment duration was 5 [0‑7] cycles. Almost all subjects (9/11;82%) experienced marked and rapid reductions in lymphadenopathy within the first 2 cycles. The lymphocyte mobilization that is expected with PI3Kδ inhibition was significantly reduced in magnitude and duration and persisted past Cycle 1 in only 1 patient. Early follow up data support a favorable safety profile and confirm a lack of clinically significant myelosuppression. Elevated baseline levels of CCL3, CCL4, CXCL13, and TNFa were significantly reduced after 28 days of treatment. Conclusions: GS-1101/ofatumumab offers a well-tolerated noncytotoxic combination regimen with substantial activity in previously treated patient with bulky adenopathy. Data on the complete cohort of 21 subjects will be presented.

Abstract Abstract 4017 Phosphatidylinositide 3-kinases (PI3K) are a family of lipid kinases that are involved in signaling events which control a diverse number of cellular processes. The class I PI3Ks contain 4 isoforms designated p110a, b, d, g, and are activated by cell surface receptors. Aberrant regulation of the PI3K signaling pathway is frequently observed in a wide range of human malignancies including those of hematological origin and has been shown to play an important role in tumor progression. GS-9820 is a highly selective and potent p110d inhibitor (IC50 of 14 nM) with 114- to 400-fold selectivity over the other class I PI3K enzymes and no activity against Class II and III PI3K family members or other PI3K-related proteins including mTOR and DNA-PK. Although a role for PI3Kd has been shown in multiple myeloma (MM), GS-9820 has not been previously evaluated in combination with anti-MM agents in primary MM tumor cells. Hence, we determined the effects of GS-9820 as a single agent and in combination with melphalan, dexamethasone, doxorubicin, or bortezomib on primary MM cells. GS9820 alone inhibited MM tumor cell proliferation in a concentration-dependent fashion with a 50% growth inhibition (IC50) of primary MM cells between 1–10 μM. Notably, combinations of GS-9820 (100nM-1μM) and melphalan (10 μM) or dexamethasone (1 μM) significantly decreased cellular proliferation (P < 0.05), compared to either drug alone in all 6 MM BMMC samples. GS-9820 was synergistic when combined with doxorubicin on primary MM cells from two of these patients' samples. Similarly, this PI3K inhibitor synergized when it was combined with bortezomib on primary MM cells from two of these patients. Using our LAGk-2 human tumor xenograft model, the combination of GS-9820 and melphalan provided greater growth inhibition than the individual drugs alone. Specifically on day 42 post-tumor implantation, LAGk-2-bearing mice treated with single agent GS-9820 did not show a significant reduction in tumor growth compared to vehicle-treated mice. In contrast, melphalan alone resulted in a significant decrease in tumor size when compared to vehicle-treated mice at this same time point (P = 0.0302). Importantly, the combination of GS-9820 plus melphalan resulted in statistically significantly smaller tumors when compared to melphalan alone (P = 0.0495), GS-9820 alone (P = 0.0061) and vehicle-control (P = 0.0025). In this study, we demonstrate that the combination of GS-9820 with melphalan or dexamethasone markedly inhibits primary MM cell proliferation in vitro. Furthermore, the combination of GS-9820 and melphalan shows enhanced anti-MM effects compared to single agent treatment in vivo using theLAGk-2 human xenograft MM model. The results from these studies suggest that the combination of the PI3K inhibitor, GS-9820, and other anti-MM drugs may be an effective treatment for MM patients. Disclosures: Johnson: Gilead Sciences: Employment. Lannutti:Gilead Sciences: Employment.

Abstract 3719 The clinical efficacy of mTOR inhibition in MCL is limited by known resistance pathways mediated through IRS-1 and mTORC2. Simultaneous inhibition of other molecules downstream of the B cell receptor, such as PI3Kδ, may abrogate such negative feedback mechanisms. PI3Kδ inhibition using GS-1101 has demonstrated early efficacy in MCL. Taken together, the combination of mTORC1 and PI3Kδ inhibition may represent a rationale combination to test in MCL.To this end, we utilized a panel of B cell lymphoma lines including established MCL cell lines (Granta, Jeko, Mino, Rec-1, HBL-2, Z-138), cytarabine resistant MCL lines (MinoAraCR, JekoAraCR, Rec-1AraCR, HBL-2AraCR) and primary MCL cells isolated from patients. In all cell lines, dose-finding experiments using GS-1101 and the mTOR inhibitors temsirolimus and everolimus were performed in triplicates. Cell viability was determined using an Alamar Blue reduction assay. Proteins downstream of PI3K – mTOR signaling were evaluated by western blot analysis. Synergy between the agents was evaluated using Laska et al's model–free test. For in vivo studies, severe combined immunodeficiency mice were injected with 10×106 Z-138 cells on day 0. GS-9820, a PI3Kδ inhibitor optimized for murine studies, was used in lieu of GS-1101. Upon detection of tumor engraftment, animals were divided into 6 groups, each containing 5 mice; Control, GS-9820 at 10 and 20mg/kg/dose, temsirolimus at 10 and 20mg/kg/dose, and GS-9820 plus temsirolimus at 10mg/kg/dose each. GS-9820 was administered by gastric lavage twice daily on days +15 to +19 and +22 to +26. Temsirolimus was administered via tail vein injection on days +15, +17, +19, +22, +24, and +26. Tumor measurements were used to determine therapeutic activity.The initial screen of lymphoma histologic subtypes demonstrated that cell viability was reduced across Burkitt, diffuse large B cell and MCL lines exposed to GS-1101. In MCL lines, the cell viabilities observed after 48 h treatments with GS-1101 (5uM) were 80% ± 6.9, 66% ± 2.2 and 68% ± 4.7 in Granta, Jeko and Rec-1 cells respectively. No difference was observed in cytarabine resistant cells suggesting non-cross resistance with cytarabine. The activity in primary MCL cells was similar using GS-1101 (5uM) [viability range 55%-65%] while peripheral blood mononuclear cells (PBMCs) appeared less sensitive to GS-1101 [78% ± 2.4].Both mTOR inhibitors provided moderate reductions in viability after 48 h exposures. Compared to untreated controls, the viabilities of Granta, Jeko and Rec-1 cell lines after 48 h exposures to temsirolimus (5nM) were 73% ± 1.3, 53% % ± 6.9 and 54% ± 2.0 respectively as well as 68% ± 2.9, 50% ± 7.4 and 55% ± 2.0 respectively after everolimus (5nM). Similar results were observed in primary MCL cells using temsirolimus (5nM) [range 80%-85%] while PBMCs were largely unaffected [90% ± 2.2].The combination of GS-1101 and either mTOR inhibitor produced largely additive reductions in cell viability. Synergistic interactions were observed in Rec-1 cells for 8 dose combinations of GS-1101 (0.1–5.0uM) and either temsirolimus (1–5nM) or everolimus (1–5nM) (unadjusted p < 0.05 for all 8 combinations). Evidence of synergy was insufficient at any combination after adjustment for multiple comparisons over the 3 cell lines. Sequential administration using 24 h pretreatment with each agent was evaluated; no benefit over simultaneous administration was demonstrated. Consistent with known mechanisms of action, immunoblotting revealed decreased 4EBP1 and S6K phosphorylation with mTOR inhibition while PI3K inhibition consistently decreased Akt phosphorylation.In vivo , GS-9820 appears active in the Z-138 xenografts at early time points. Tumor size was reduced to 60% ± 5.5 of control at day 18 and 23 using either 10 or 20 mg/kg of GS-9820. Testing of GS-9820 in combination with temsirolimus in this model is ongoing.Our findings indicate that PI3Kδ inhibition using GS-1101 and GS-9820 is active in vitro and also in a MCL murine xenograft. GS-1101 in combination with mTORC1 inhibition largely produced additive in vitro anti-lymphoma effects in MCL. Ongoing work is aimed at understanding the differences in molecular events downstream of PI3K and mTOR inhibition comparing Rec-1 cells, where synergy was demonstrated, with other cell lines to provide insight into optimal therapeutic combinations and to determine in which molecularly defined subsets of MCL they may be most active.Disclosures: Johnson: Gilead Sciences: Employment. Lannutti: Gilead Sciences Inc: Employment.

Abstract 191 Introduction: PI3Kdelta drives proliferation and survival in malignant B-cells. GS-1101 is an orally bioavailable, small-molecule inhibitor of PI3Kdelta that has shown considerable monotherapy activity when given at dose levels of 3100 mg BID in patients with heavily pretreated CLL. Methods and Patients: This Phase 1 combination study has evaluated repeated 28-day cycles of GS-1101 in combination with rituximab and/or bendamustine in patients with previously treated CLL. GS-1101 was administered starting on Day 1 of Cycle 1 with rituximab (R) (375 mg/m2 given weekly for 8 doses) (GS-1101/R regimen), with bendamustine (B) (90 mg/m2 given on Days 1 and 2 of each cycle for 6 cycles) (GS-1101/B regimen), or in combination with R (375 mg/m2, on Day 1 of each cycle for 6 cycles) and B (90 mg/m2 given on Days 1 and 2 of each cycle for 6 cycles) (GS-1101/BR regimen). Initial cohorts of patients received a GS-1101 dose of 100 mg/dose BID in the GR or GB regimens. Thereafter, all patients received a GS-1101 dose of 150 mg/dose BID. Tumor response was evaluated according to standard criteria (Hallek 2008). Chemokine/cytokine plasma levels were assessed at baseline and on Day 28 of therapy using multiplexed bead suspension arrays. Results: The study enrolled a total of 51 patients with CLL. Patient characteristics and safety and efficacy results are depicted in the table The majority of patients had bulky adenopathy and had undergone extensive prior therapy, with virtually all patients receiving prior rituximab and many receiving prior bendamustine. Grade 33 adverse events and lab abnormalities were generally consistent with those expected with each of the single agents. Lymph node shrinkage was rapid, and almost all evaluable patients had reductions in lymphadenopathy. As reported by investigators, the overall response rates (ORR) for the GS-1101/R, GS-1101/B, and GS-1101/BR regimens were 78%, 82% and 87%, respectively. With a minimum follow-up of 340 weeks for all regimens, 1-year progression-free survival (PFS) rates were 74%, 88% and 87% in the GS-1101/R, GS-1101/B, and GS-1101/BR treatment groups, respectively. Disease-associated chemokines/cytokines were commonly elevated at baseline and were significantly reduced by GS-1101-based combination treatment. Conclusions: A favorable safety profile and lack of overlapping toxicities allows the oral PI3Kdelta inhibitor, GS-1101, to be delivered at the full single-agent starting dose when coadministered with chemoimmunotherapies in heavily pretreated patients with CLL. GS-1101-based combination therapies with rituximab and/or bendamustine offer major and rapid reductions in lymphadenopathy and durable tumor control. Based on these results, Phase 3 trials evaluating the efficacy of GS-1101 in combination with R or BR have been initiated (NCT01539512 [GS-1101/placebo+R], NCT01569295 [GS-1101/placebo+BR]). Disclosures: Coutre: Gilead: Consultancy. Off Label Use: Phase 1 trial of GS-1101 (CAL-101)-based combination therapy. Leonard:Gileade: Consultancy. Barrientos:Gilead: Research Funding. de Vos:Gilead: Consultancy. Sharman:Gilead: Honoraria, Research Funding. Holes:Gilead: Employment. Lannutti:Gilead Sciences Inc: Employment. Johnson:Gilead Sciences: Employment. Miller:Gilead: Employment. Jahn:Gilead: Employment.

Abstract Abstract 2699 Introduction: PI3Kδ is expressed in cells of hematopoietic origin where it regulates survival and proliferation of normal and malignant B-cells. CAL-101 (GS-1101) is an orally bioavailable, small-molecule inhibitor that selectively targets PI3Kδ. A prior Phase 1 study established 150 mg/dose BID as an appropriate single-agent starting dose for GS-1101 and demonstrated that GS-1101 monotherapy is associated with substantial clinical activity in patients with hematologic malignancies. Methods and Patients: This Phase 1 study has evaluated repeated 28-day cycles of GS-1101 in combination with rituximab and/or bendamustine in patients with previously treated iNHL. GS-1101 (G) was administered starting on Day 1 of Cycle 1 with rituximab (R) (375 mg/m2 given weekly for 8 doses, GR regimen), with bendamustine (B) (90 mg/m2 given on Days 1 and 2 of each cycle for 6 cycles, GB regimen), or in combination with R (375 mg/m2, on Day 1 of each cycle for 6 cycles) and B (90 mg/m2 given on Days 1 and 2 of each cycle for 6 cycles, GRB regimen). Initial cohorts of patients received GS-1101 at a dose of 100 mg/dose BID in the GR or GB regimens. Thereafter, all patients received GS-1101 at a dose of 150 mg/dose BID in the GR, GB, or GRB regimens. Chemokine/cytokine plasma levels were assessed at baseline and on Day 28 of therapy using multiplexed bead suspension arrays. Tumor response was evaluated according to standard criteria (Cheson et al. 2007). Results: At data cutoff, the study had enrolled 37 patients with iNHL. Patient characteristics, histological subtyping, safety, and efficacy results are depicted in the table. The majority of patients were >60 years of age and had undergone extensive prior therapy. Grade ≥3 adverse events were generally consistent with those expected with each of the single agents. All evaluable patients had reductions in lymphadenopathy, resulting in an overall response rate (ORR) of >65% for all regimens. In 3 patients among the 24 patients receiving either GB or GRB, 3 complete responses were observed. Lymph node shrinkage was rapid; responses generally occurred within ≤2 cycles. Disease-associated chemokines/cytokines were commonly elevated at baseline and were reduced by GS-1101 treatment; in 20 evaluable patients, mean (±SEM) values declined from 302 (±68) to 62 (±14) pg/mL for CCL17 (p=0.001), from 2512 (±332) to 879 (± 88) pg/mL) for CCL22 (p=0.0001), from 517 (± 88) to 107 (± 34) pg/mL for CXCL13 (p=0.0001), and from 33 (± 5.4) to 18 (± 1.8) pg/mL for TNFα (p=0.007). Conclusions: A favorable safety profile and lack of overlapping toxicities allows the oral PI3Kδ inhibitor, CAL-101 (GS-1101), to be delivered at the full single-agent starting dose when coadministered with chemoimmunotherapies in heavily pretreated patients with iNHL. GS-1101-based combination therapy with rituximab and/or bendamustine offers major and rapid reductions in lymphadenopathy. The data from this trial will be used to design Phase 3 combination studies of GS-1101 in patients with iNHL. Disclosures: de Vos: Gilead Sciences Inc: Consultancy. Flinn:Gilead Sciences Inc: Research Funding. Coutre:Gilead Sciences Inc: Consultancy. Leonard:Gilead Sciences Inc: Consultancy. Fowler:Gilead Sciences Inc: Consultancy. Sharman:calistoga: Honoraria; Pharmacyclics: Honoraria; Genentech: Honoraria; Rigel: Research Funding; Portola: Consultancy; Pharmacyclics: Consultancy; Gilead: Consultancy. Holes:Gilead: Employment. Lannutti:Gilead: Employment. Johnson:Gilead Sciences Inc: Employment. Jahn:gILEAD: Employment. Miller:Gilead: Employment.

PI3Kδ is expressed in cells of hematopoietic origin, where it regulates proliferation and survival of normal and malignant B-cells and orchestrates the migration of B-cells. CAL-101 is an orally available PI3Kδ-selective inhibitor that shows substantial single-agent and combination clinical activity in patients with lymphoid malignancies.

Abstract 3926 Phosphatidylinositide 3-kinases (PI3Ks) are a family of lipid kinases that are involved in signaling events which control a diverse number of cellular processes. The class I kinases contain 4 isoforms designated p110α, β, δ, γ, and are activated by cell surface receptors. Aberrant regulation of the PI3K signaling pathway is frequently observed in human malignancies including those of hematological origin. CAL-101 is an oral p110δ-specific inhibitor which has shown preclinical and clinical activity in non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL). This compound is a potent p110δ inhibitor (EC 50 of 65 nM in a whole-blood assay) with >200-fold selectivity over the other class I PI3K isoforms and no activity against Class II and III PI3K family members or other PI3K-related proteins, including mTOR and DNA-PK. Prior in vitro NHL studies revealed that CAL-101 induces caspase-dependent apoptosis, and inhibits CD40L-, BAFF-, CXCL12- and CXCL13-derived survival signals in cellular models (Lannutti BJ, et al., Blood 2010). To investigate the potential role of p110δ in Hodgkin lymphoma (HL) we screened a number of HL cell lines for p110δ isoform expression and constitutive PI3K pathway activation. We report high levels of p110δ protein and activated Akt in 5 of 5 HL cell lines evaluated (L428, L540, L591, L1236, KM-H2). Inhibition of p110δ with CAL-101 treatment of cell lines resulted in a reduction of Akt phosphorylation and a decrease in cellular viability. Because previous studies have established the importance of signals from the microenvironment for the survival and proliferation of malignant cells as well as for their resistance to standard therapies, we investigated the effect of p110δ inhibition by CAL-101 in HL cell line-stroma cocultures. In this setting, CAL-101 overcame tumor cell growth induced by coculture of HL cells with bone marrow stromal cells. In addition, CAL-101 induced dose-dependent apoptosis of HL cells at 48 hours. Furthermore, stromal cell coculture resulted in increased CCL5, CCL17, and CCL22 levels; productions of these chemokines by HL cells cultured in the presence of stromal cells were reduced by CAL-101 in a dose-dependent manner. These results indicate that specific inhibition of p110δ may disrupt signals between HL cells and their microenvironment, thereby providing the preclinical rationale for clinical evaluation of CAL-101 as a novel therapeutic approach in patients with Hodgkin lymphoma. Disclosures: Meadows: Calistoga Pharmaceuticals: Employment. Kashishian: Calistoga Pharmaceuticals: Employment. Johnson: Calistoga Pharmaceuticals: Employment. Lannutti: Calistoga Pharmaceutical Inc.: Employment.