Safety and Efficacy of Venetoclax Combined with Rituximab, Ifosfamide, Carboplatin and Etoposide Chemoimmunotherapy (VICER) for Treatment of Relapsed Diffuse Large B Cell Lymphoma: Results from the Phase 1 Study

Abstract Introduction: Diffuse large B cell lymphoma (DLBCL) patients (pts) with relapsed or refractory (r/r) disease after front line chemoimmunotherapy have poor survival. Standard second line therapy for r/r DLBCL consists of platinum-based chemotherapy followed by autologous stem cell transplant (ASCT). Approximately 50% of pts do not respond to second line therapy, highlighting the need for increased efficacy of these regimens. The antiapoptotic protein Bcl-2 is overexpressed in approximately 30% of DLBCL cases. Preclinical and early clinical data suggest that addition of venetoclax (VEN), a potent selective Bcl-2 inhibitor, to chemoimmunotherapy augments response rates and durability in lymphoma. We conducted a phase 1 dose escalation and dose expansion study to evaluate the safety and efficacy of VEN in combination with R-ICE (rituximab, ifosfamide, carboplatin and etoposide) (VICER) r/r DLBCL pts. Here we present the results after completion of VEN dose escalation. Methods: Patients (≥18 years of age) with r/r DLBCL who failed one or two lines of therapy were enrolled. The primary objective was to determine the recommended phase 2 dose (RP2D) of VEN when combined with R-ICE. VEN was given orally on days 1 - 10 of each 21 - day cycle x 3 cycles. Dose escalation was conducted according to a 3+3 design, with 3 dose levels (400, 600 and 800mg). R-ICE was given at standard dose and schedule on days 1 - 3 of each cycle for 3 cycles. No intra-patient dose escalation was allowed. Tumor lysis syndrome (TLS) mitigation included inpatient administration, hydration, allopurinol and frequent laboratory evaluation during cycle 1. All patients received pegfilgrastim; use of prophylactic antibiotics during neutropenia was left at the discretion of the treating physician. Results: As of July 20, 2018, 18 pts with DLBCL (14 male, 4 female) were enrolled (VEN 400mg, n = 3; 600 mg, n = 3; 800 mg, n = 12). Median age of pts was 55.5 years [range 27-78]. All pts received rituximab and anthracycline containing first - line therapy, 4 patients had failed a second line of therapy. One patient experienced dose limiting toxicity (DLT) at 800 mg VEN, with acute renal failure, febrile neutropenia, sepsis and rapid tumor progression and died after cycle 1. No other DLTs were observed. Hematologic toxicity was common, with grade ≥3 anemia in 6 (33%) pts; grade ≥3 neutropenia in 14 (78%) pts and grade ≥3 thrombocytopenia in 10 (55%) pts. Five (28%) pts experienced febrile neutropenia. The most common non-hematologic all-grade treatment emergent adverse events (TEAEs) were fatigue (7 [38%] pts), nausea (6 [33%] pts); diarrhea (6 [33%] pts), anorexia (5 [27%] pts], infection (5 [27%] pts) and sensory neuropathy (5 [27%] pts). Grade ≥3 TEAEs included infection (4 [22%] pts), cholecystitis (2 [11%]) and one case each (5.5%) of peripheral edema, acute renal failure, acute coronary syndrome, atrial fibrillation, hyponatremia and hypokalemia. One case of laboratory TLS occurred, but no clinical TLS was observed. At data cutoff, the intent-to-treat (ITT) population included 13 patients that had at least one cycle of therapy and end of treatment response or had discontinued prior to response assessment; 3 pts did not complete all planned cycles of VICER: one patient died after DLT, one patient proceeded to ASCT in complete remission (CR) after 2 cycles and another withdrew after cycle 1, achieving partial remission (PR) with additional 2 cycles of R-ICE. Nine pts (69%) achieved CR and 2 (15%) achieved PR (overall response rate (ORR): 11/13 [84.6%]) (Tables 2 and 3). Figure 1 depicts tumor response data. Among 11 responding pts, 7 have undergone stem cell collection, with a median CD34 cell count of 3.73x106 cells/kg. Seven pts have completed their ASCT, with hematopoietic engraftment in all cases. Median follow up of patients in CR/PR is 6 months (range 1 - 12), none has experienced progression. Conclusions: In this Phase 1 study, VICER shows encouraging antilymphoma activity in r/r DLBCL, including double hit/double expressor lymphomas, with high rates of complete metabolic response (69% CR by PET), which is higher than historical levels reported with R-ICE alone (CR typically Download : Download high-res image (661KB) Download : Download full-size image Disclosures Caimi: Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees; ADC Therapeutics: Research Funding; Celgene: Speakers Bureau. Hill: Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees.