Pettinger, Adam

Akt is a downstream target of B cell receptor signaling and is a central regulator of CLL cell survival. We aim to investigate the safety and efficacy of the Akt inhibitor MK‐2206 in combination with bendamustine and rituximab (BR) in relapsed and/or refractory CLL in a phase I/II study. A standard phase I design was used with cohorts of three plus three patients to determine the maximum tolerated dose (MTD) of MK‐2206 in combination with BR in relapsed CLL. Single‐agent MK‐2206 (weekly dosed) was administered one‐week in advance before BR on cycle 1 and subsequently was given with BR at the same time for cycle 2‐6. Phase II employed the MTD of MK‐2206 with BR to evaluate safety and efficacy of this study combination. Thirteen relapsed/refractory CLL were treated for maximal 6‐cycle of therapy. The maximum tolerated dose of MK‐2206 was 90 mg by mouth once weekly. The most common grade 3/4 adverse events were neutropenia (46%), febrile neutropenia (23%), rash (15%), diarrhea (15%), and thrombocytopenia (15%). Overall response rate was 92% with a median progression free survival and treatment free survival of 16 and 24 months, respectively. Five patients (38%) achieved complete remission or complete remission with incomplete count recovery, two of whom were MRD negative. The efficacy and tolerability of this combination indicates that Akt inhibition combined with chemoimmunotherapy is a promising novel treatment combination in CLL and deserves further prospective clinical trial.

Abstract Introduction. First-line chemoimmunotherapy (CIT) has significantly increased the complete remission (CR) rate for patients with CLL; however, relapse is a common event and strategies aimed at eradicating disease more effectively are needed. Vascular Epithelial Growth Factor (VEGF) plays a crucial role in the cross talk between CLL B cells and their microenvironment. In addition low baseline VEGF levels predict a better response to CIT. Testing the combination of an anti-VEGF agent with CIT was therefore assessed by us in upfront CLL patients. Methods. Here we report the results of a phase II open-label randomized trial comparing the combination of bevacizumab, an anti-VEGF monoclonal antibody, with pentostatin, cyclophosphamide and rituximab (PCR-B) to PCR alone as front-line therapy in previously untreated patients with CLL. VEGF, b-fibroblast growth factor (FGF), thrombospondin (TSP)-1, chemokine ligand (CCL)-3 and CCL-4 plasma levels were measured at baseline and at time of response assessment. Results. Between 01/2009 and 01/2013, 62 patients were accrued in the study, 32 in the arm A (PCR-B) and 30 in arm B (PCR alone). A higher rate of grade 3-4 cardiovascular toxicity was observed with the use of PCR-B (34% vs 0%, p<0.001): this included 7 cases of hypertension, 2 cases of congestive heart failure, 1 myocarditis, and 1 case of torsade de point. A higher CR rate (50% vs 33%, p = 0.21) and a significantly longer median progression-free (p = 0.04) and treatment-free (p = 0.05) survival were achieved with the use of PCR-B. No difference in chemokine kinetics was observed between the 2 arms, except for VEGF, which significantly increased after PCR-B. In the PCR-B arm, chemokine kinetics for CCL-3 (median drop 5.0 vs. median drop 31.8, respectively; p = 0.02) and CCL-4 (median drop 23.8 vs. median drop 120.9, respectively; p = 0.01) were significantly associated with achievement of CR. No significant correlations were found between cytokine plasma levels and responses for patients treated in the PCR only arm. Conclusions. The addition of bevacizumab to CIT is safe and effective, although associated with higher cardiovascular toxicity, in particular hypertension. The addition of bevacizumab produces higher CR rates, translating into improved progression-free survival, and is associated with decreased plasma levels of CCL-3 and CCL-4. Citation Format: PAOLO STRATI, TAIT D. SHANAFELT, BETSY LAPLANT, ADAM PETTINGER, CONNIE LESNICK, DANIEL NIKCEVICH, TIMOTHY CALL, WEI DING, CURTIS HANSON, NEIL KAY. The addition of bevacizumab to chemoimmunotherapy prolongs progression-free survival in patients with chronic lymphocytic leukemia (CLL) through modulation of the microenvironment. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1423.

Abstract Ofatumumab (OFA), a human CD20-targeting mAb, kills B lymphocytes using the innate immune system including complement-dependent cytotoxicity (CDC). The efficacy of OFA in patients with chronic lymphocytic leukemia (CLL) is limited by drug resistance, which is not well characterized. To better understand mechanisms of resistance, we prospectively studied CLL cells isolated from blood samples collected before and after in vivo exposure to the initial dose of OFA therapy in 25 patients undergoing their first treatment for progressive CLL. As previously reported, OFA therapy rapidly decreased the absolute lymphocyte count, CD20 expression by CLL cells, and serum complement levels. We now show that after administration of the first dose of OFA, there was a modest rebound in the absolute lymphocyte count and serum complement levels, but substantial ongoing loss of CD20 expression by CLL cells. These post-OFA treatment CLL cells were highly resistant to OFA-mediated CDC but retained sensitivity to alemtuzumab-mediated CDC in vitro. Posttherapy serum OFA levels correlated inversely with both the amount of pretreatment circulating cell-bound CD20 and with the decrease in this value following treatment. In vitro OFA-mediated CDC did not predict clinical responses, and the patients with first-dose reactions to OFA did not have markers of increased complement activation in vivo. We propose that optimal efficacy of CD20- targeted therapy for CLL requires determining an mAb dose size and frequency that optimizes CLL killing without exceeding the capacity of the cytotoxic mechanisms and thus minimizes loss of CD20 expression in the surviving CLL cells.

Key Points Lenalidomide consolidation repairs T-cell immune synapses in CLL patients. Lenalidomide consolidation improved the quality of response in CLL patients treated with chemoimmunotherapy.