ALBERT

Description: Key Points This clinical study assessed idelalisib, a selective PI3Kδ inhibitor, in 64 patients with relapsed, indolent non-Hodgkin lymphoma. Idelalisib treatment rapidly induced durable disease responses in heavily pretreated patients with a favorable safety profile.

Description: Abstract 2832 Introduction: The class I phosphatidylinositol 3-kinases (PI3Ks) regulate a variety of cellular functions relevant to oncogenesis. Expression of the PI3K p110δ isoform (PI3Kδ) is restricted to cells of hematopoietic origin where it plays a key role in B cell proliferation and survival. CAL-101 is an isoform-selective inhibitor of PI3Kδ (EC50 of 8 nM in a cell-based assay with 〉200-fold selectivity relative to other PI3K isoforms). A Phase 1 study of single-agent CAL-101 demonstrated clinical activity in patients with indolent B-cell non-Hodgkin lymphoma (NHL), mantle cell lymphoma, and chronic lymphocytic leukemia (CLL); a favorable safety profile suggested that CAL-101 might successfully be combined with other agents active against lymphoid malignancies. Methods and Patients: This Phase 1 study was undertaken to evaluate the safety and activity of CAL-101 in combination with rituximab and/or bendamustine in patients with relapsed or refractory B-cell indolent NHL and CLL. All patients received CAL-101 100 mg orally twice per day (BID) in 28-day cycles for up to 12 cycles. Patients also received either rituximab 375 mg/m2 administered weekly for 8 weeks, starting on Day 1 of Cycle 1, or bendamustine 90 mg/m2 administered on Days 1 and 2 of each cycle for 6 cycles. Tumor response was evaluated according to standard criteria. Results: At data cutoff, 12 patients were enrolled in the study, including 6 with NHL and 6 with CLL. Patients included: males/females n=8 (67%)/4 (33%) with median age [range] of 65 [55-80] years, and relapsed/refractory disease n=8 (67%)/4 (33%). The median [range] number of prior therapies was 3 [1-11]. The number (%) of patients with specific prior therapies included: rituximab n=12 (100%), alkylating agent n= 10 (83%), purine analog n=9 (75%), and anthracycline/anthracenedione n=6 (50%). All patients received CAL-101 100 mg BID; 6 patients received rituximab and 6 received bendamustine. One patient with NHL had a dose reduction of bendamustine due to hiccups and 1 patient with NHL had a dose reduction of CAL-101 due to increased ALT/AST; all other patients received the full-dose regimen with acceptable tolerability. Preliminary clinical response assessments were available for 6 patients who had completed 2 cycles of combination treatment; the results are shown in the table. Enrollment is ongoing and dose escalation of CAL-101 is planned. Updated data will be presented at the meeting. Conclusions: Early results from this Phase 1 study of CAL-101, an oral PI3Kδ isoform-selective inhibitor, in combination with rituximab or bendamustine show acceptable safety and promising clinical activity in patients with relapsed or refractory indolent B-cell NHL and CLL. Disclosures: Flinn: calistoga: Research Funding. Off Label Use: CAL-101 for NHL. Leonard:Calistoga: Consultancy, Research Funding. Holes:Calistoga: Employment. Peterman:Calistoga: Employment. Yu:Calistoga: Employment.

Description: Abstract 1774 Phosphatidylinositol 3-kinases (PI3Ks) regulate several cellular functions including motility, proliferation, and survival. PI3K pathway signaling is mediated by the Class I PI3K isoforms, α, β, δ and γ. The PI3K p110δ isoform is preferentially expressed in cells of hematological origin and in a variety of malignant cells. CAL-101 is a potent p110δ inhibitor with an EC50 of 62 nM in a whole-blood p110δ assay and 〉200-fold selectivity for p110δ relative to other PI3K isoforms. Consistent with this target selectivity, nonclinical toxicology and safety pharmacology data supported initial clinical assessment of oral CAL-101 in single-dose, multiple-dose, and food-effect studies in healthy volunteers. Because CAL-101 is a CYP450 3A4 substrate, the effect of ketoconazole (a potent CYP450 3A4 inhibitor) on CAL-101 pharmacokinetics was also evaluated in healthy volunteers. Preliminary evaluation of disposition, metabolism and elimination in healthy volunteers was achieved by coadministering a trace amount of [14C]CAL-101 and unlabeled CAL-101 either orally or intravenously (IV) with samples evaluated by accelerator mass spectrometry. CAL-101 pharmacokinetics (PK) were subsequently evaluated in patients with lymphoid malignancies. In healthy volunteers, CAL-101 was well tolerated at 400 mg (the highest single dose tested) and at 200 mg BID through 7 days (the highest multiple dose tested). The drug has also been symptomatically well tolerated in patients with lymphoid malignancies receiving CAL-101 at dose levels through 350 mg/kg (the highest dose tested) over many months. Monitorable, reversible transaminase elevations have been observed in some patients, most commonly in patients with lymphoma. No maximum tolerated dose (MTD) has been apparent. Increases in Cmax and AUC are less than dose proportional, revealing minimal gains in plasma exposure at dose levels 〉150 mg BID. The mean volume of distribution was moderate at 57.7 L. The t1/2 was ∼8 hours across all dose levels and there was no plasma accumulation over 7 or 28 days. The collective data support BID dosing at ≥150 mg; dose levels in this range maintain steady-state trough plasma concentrations that are 〉10-fold above the EC50 for the in vitro whole-blood assay. [14C]CAL-101 was metabolized to only 1 metabolite in plasma and CAL-101-derived materials were primarily excreted in feces (〉65% of total dose) with minimal elimination via urine (

Description: Abstract 55 Introduction: The class I phosphatidylinositol 3-kinases (PI3Ks) regulate cellular functions relevant to oncogenesis. Expression of the PI3K p110δ isoform (PI3Kδ) is restricted to cells of hematopoietic origin where it plays a key role in B cell proliferation and survival. In chronic lymphocytic leukemia (CLL) the PI3K pathway is constitutively activated and dependent on PI3Kδ. CAL-101 is an isoform-selective inhibitor of PI3Kδ (EC50 of 62 nM in a whole-blood assay with 〉200-fold selectivity relative to other PI3K isoforms) that inhibits PI3K signaling and induces apoptosis of CLL cells in vitro. Methods and Patients: This Phase 1 study evaluated the safety, pharmacokinetics, pharmacodynamics and clinical activity of CAL-101 in patients with relapsed or refractory hematologic malignancies. Sequential cohorts of patients were enrolled at progressively higher dose levels with cohort expansion based on toxicity profile and plasma exposure. CAL-101 was administered orally one or 2 times per day (QD or BID) continuously for 28-day cycles for up to 12 cycles (with the potential for more prolonged therapy on an extension protocol thereafter). Clinical response was evaluated according to standard criteria. Results: At data cutoff, the study had enrolled 37 patients with CLL. Patients included: males/females n=31 (84%)/6 (16%) with median age of 65 [range 37–82] years, refractory/relapsed disease n=24 (65%)/13 (35%), bulky disease n= 29 (81%), and adverse cytogenetics of del(17p), del(11q) or both n=22 (63%). The median number of prior therapies was 5 [range 2–14]. The number (%) of patients with specific prior therapies included: rituximab n=37 (100%), purine analog n=37 (100%), alkylating agent n= 31 (84%), and alemtuzumab n=12 (32%). CAL-101 dose levels were 50 mg BID (n=1), 100 mg BID (n=4), 150 mg BID (n=11), 200 mg BID (n=10), 350 mg BID (n=7) and 300 mg QD (n=4). The median number of treatment cycles was 9 [range 1–13], with 21 (57%) patients continuing on treatment (11 on study and 10 on the extension protocol after 12 cycles). Symptomatic adverse events were infrequent, usually low-grade, and not clearly CAL-101-related. Grade ≥3 pneumonias occurred in 9 (24%) patients. Grade ≥3 hematological laboratory abnormalities included neutropenia n=9 (24%), thrombocytopenia n=4 (11%) and anemia n=3 (8%) that were not usually considered CAL-101-related. A pharmacokinetic analysis of dose-proportionality showed minimal increases in plasma Cmax and AUC at CAL-101 doses 〉150 mg BID; these data, taken together with the tumor regression results, have proved helpful in supporting Phase 2–3 dose selection. Flow cytometry of CLL cells from patients showed that CAL-101 reduced constitutive expression of phospho-AKT to background levels when measured after 1 week of treatment (p50% increase from baseline. Conclusions: CAL-101, an oral PI3Kδ isoform-selective inhibitor, shows acceptable toxicity, positive pharmacodynamic effects, and favorable clinical activity in heavily pretreated patients with CLL, including patients with refractory disease, bulky lymphadenopathy, and poor-prognosis cytogenetics. The high level of lymph node regression and prolonged duration of symptomatic tumor control strongly support evaluation of CAL-101 alone and in combination with other chemo/immunotherapy approaches to CLL management. Disclosures: Byrd: Calistoga Pharmaceuticals: Consultancy, Equity Ownership. Brown:Calistoga: Consultancy. Kahl:Calistoga Pharmaceuticals: Consultancy, Research Funding. Lannutti:Calistoga Pharmaceutical Inc.: Employment. Giese:Calistoga Pharmaceuticals: Equity Ownership. Webb:Calistoga Pharmaceuticals: Employment. Ulrich:Calistoga Pharmaceuticals: Employment, Equity Ownership. Peterman:Calistoga Pharmaceuticals: Employment. Holes:Calistoga Pharmaceuticals: Employment. Yu:Calistoga Pharmaceuticals: Employment, Equity Ownership.

Description: Abstract 1777 Introduction: The class I phosphatidylinositol 3-kinases (PI3Ks) regulate cellular functions relevant to oncogenesis. Expression of the PI3K p110δ isoform (PI3Kδ) is restricted to cells of hematopoietic origin where it plays a key role in B-cell proliferation and survival. In non-Hodgkin lymphoma (NHL) cells, constitutive PI3Kδ-dependent PI3K pathway activation is frequently observed. CAL-101 is an isoform-selective inhibitor of PI3Kδ that inhibits PI3K signaling and induces apoptosis of NHL cell lines in vitro. Methods and Patients: This Phase 1 study evaluated the safety, pharmacokinetics and activity of orally administered CAL-101 in patients with relapsed or refractory hematologic malignancies. Sequential cohorts of patients were enrolled at progressively higher dose levels with cohort expansion based on toxicity profile and plasma exposure. CAL-101 was administered orally once or 2 times per day (QD or BID) continuously in 28-day cycles for up to 12 cycles (with the potential for more prolonged therapy on an extension protocol thereafter). Tumor response was evaluated based on standard criteria but without a requirement for PET imaging. Results: At data cutoff, the study had enrolled 55 patients with NHL; 28 patients had indolent NHL (follicular lymphoma n=15, small lymphocytic lymphoma n=6, Waldenstrom's macroglobulinemia n=4, marginal zone lymphoma n=3) and 27 had aggressive NHL (mantle cell lymphoma [MCL] n=18, diffuse large B-cell lymphoma [DLBCL] n=9). Patient characteristics included 69% males (38 vs 17 females), median age [range] of 68 [32-82] years, 44% with refractory disease and 56% with relapsed disease. The median [range] number of prior therapies was 5 [1-12]. The proportion of patients with specific prior therapies included: indolent NHL-rituximab 96%, alkylator 86%, anthracycline 50%, purine analog 36%; aggressive NHL-rituximab 100%, alkylator 100%, anthracycline/anthracenedione 96%, plus bortezomib 72% in MCL patients. CAL-101 dose levels were 50 mg BID (n=2), 100 mg BID (n=11), 150 mg BID (n=8), 200 mg BID (n=16), 350 mg BID (n=9) and 300 mg QD (n=9). The median [range] number of treatment cycles was 4 [1-16], with 16 (29%) patients continuing on treatment (11 on study and 5 on the extension protocol after 12 cycles). Symptomatic adverse events were infrequent, usually low-grade, and not clearly CAL-101-related. Grade ≥3 hematological laboratory abnormalities included neutropenia n= 5 (9%), lymphopenia n=3 (5%), and thrombocytopenia n=3 (5%) with uncertain relationship to CAL-101. Grade≥3 ALT/AST elevations occurred in 18 (33%) patients with onset 2–8 weeks after CAL-101 initiation and resolution 2–4 weeks after CAL-101 interruption; after resolution of ALT/AST changes, most patients were rechallenged at the same or a reduced dose of CAL-101 and the majority of these patients were able to resume treatment without recurrence of transaminase elevations. Partial responses were observed at all dose levels, with respective overall n/N (response rates) in evaluable patients of 15/24 (62%) for indolent NHL, 10/16 (62%) for MCL and 0/9 (0%) for DLBCL. Respective response rates by relapsed or refractory status were 9/13 (69%) and 6/11 (55%) for indolent NHL and 8/11 (73%) and 2/5 (40%) for MCL. The median duration of response had not been reached in indolent NHL patients; 5 patients have had response durations of ≥6 months with response durations ranging to 〉16 months. The median [range] duration of response was 3 months [1 month to 8 months] in MCL. Pharmacodynamic data have supported drug activity; plasma concentrations of chemokines CCL22 and CCL17 were elevated at baseline and showed significant decreases within 1 cycle of CAL-101 treatment (p150 mg BID; these data, taken together with the tumor regression results, have proved helpful in supporting Phase 2–3 dose selection. Conclusions: CAL-101, an oral PI3Kδ isoform-selective inhibitor, shows acceptable safety and promising pharmacodynamic and clinical activity in patients with indolent NHL and MCL. The high rate of tumor regressions and protracted durations of tumor control in heavily pretreated patients support advancing CAL-101 into additional studies, both as a single agent and in combination with chemo/immunotherapy. Disclosures: Kahl: calistoga: Consultancy, Research Funding. Off Label Use: CAL-101 for relapsed lymphoma. Byrd:Calistoga Pharmaceutical Inc.: Equity Ownership. Flinn:calistoga: Research Funding. Wagner-Johnston:calistoga: Research Funding. Spurgeon:calistoga: Research Funding. Furman:GlaxoSmithKline: Clinical research funding, Consultancy, Research Funding, Speakers Bureau; Genentech: Clinical Research Funding, Consultancy, Research Funding, Speakers Bureau; Cephalon: Speakers Bureau, Speakers bureau; Calistoga: Consultancy, Honoraria; Celgene: Clinical Research, Consultancy, Research Funding. Brown:Genzyme: Research Funding; Celgene: Consultancy, Research Funding; Calistoga: Consultancy; Genentech: Consultancy. Coutre:calistoga: Research Funding. Lannutti:Calistoga Pharmaceutical Inc.: Employment. Ulrich:Calistoga Pharmaceuticals: Employment, Equity Ownership. Webb:Calistoga Pharmaceuticals: Employment. Peterman:Calistoga Pharmaceuticals: Employment. Holes:Calistoga Pharmaceuticals: Employment.

Description: Key Points This clinical study assessed idelalisib, a selective PI3Kδ inhibitor, in 40 patients with relapsed/refractory MCL. In a dose-escalation trial in heavily pretreated patients, an overall response rate of 40% was observed with an acceptable safety profile.

Description: Key Points Idelalisib was evaluated in 54 patients with heavily pretreated chronic lymphocytic leukemia, and target inhibition was documented in vivo. Oral idelalisib therapy demonstrated a favorable safety profile and rapidly induced durable disease control in the majority of patients.