Updated Interim Results of the Safety and Efficacy of Different Lenalidomide Starting Dose Regimens in Patients with Relapsed or Refractory (rel/ref) Chronic Lymphocytic Leukemia (CLL) (CC-5013-CLL-009 Study)
Authors: Wendtner Clemens , Hallek Michael , Fraser Graeme , Michallet Anne-Sophie , Hillmen Peter , Duerig Jan , Gregory Stephanie A. , Kalaycio Matt , Stilgenbauer Stephan , Buehler Andreas , Kipps Thomas J. , Purse Brendan , Zhang Jennie , Mei Jay , Chanan-Khan Asher 
Published: October 2019

Abstract
Abstract 3925

Introduction:
CLL patients (pts) who relapse following purine-analog or bendamustine-based treatments have a poor prognosis. These pts have limited therapeutic options and novel agents with alternative mechanisms of action are needed. Several phase 1 and 2 trials in rel/ref CLL showed promising activity with escalating dose regimens of lenalidomide (LEN). In other phase II studies improved clinical responses to lenalidomide appeared to correlate with dose levels > 5mg/day. This phase 2 trial investigates the safety of LEN initiated at 3 different starting doses followed by a step-wise dose escalation as tolerated in rel/ref CLL.

Methods:
In this ongoing trial, eligible pts with rel/ref CLL who have received ≥ 1 prior treatment regimen containing purine-analog or bendamustine are being enrolled. The objectives of this study are to evaluate primarily the safety and secondarily the efficacy of different LEN dose regimens. Pts are randomized 1:1:1 to receive a double-blinded starting dose of 5 mg, 10 mg, or 15 mg oral LEN on days 1–28 of each 28-day cycle. In all 3 treatment arms, the dose is escalated by 5 mg increments every 28 days to reach a maximum dose of 25 mg/d, depending on tolerability. In instances of poor tolerability, dose reductions also occur in 5 mg steps. Pts are stratified by relapsed versus refractory status to their last purine-analog or bendamustine-based treatment regimen and according to age (< 65 vs ≥ 65 years). Tumor lysis syndrome (TLS) prophylaxis comprises of oral hydration and allopurinol 300 mg/day and is initiated ≥ 3 days prior to starting study drug and for a minimum of the first 3 treatment cycles. A total of 105 pts are planned for enrollment to the study. Per protocol, unblinded interim analyses were conducted by the independent Data Monitoring Committee (DMC) after 18 subjects completed 1 cycle and continue at 13-week intervals.

Results:
To date, 95 pts are enrolled at a median age of 64 years (range 32–81). Enrolled pts are primarily male (67%) and Caucasian (92%). Cytogenetic data are available for 73 pts; 21% have del(17p), 55% have del(13q), 25% have del(11q), and of 72 patients evaluable for trisomy 12, 11 patients (15%) tested positive. IGVH is unmutated in 77% of 77 evaluable pts and 44% of 84 evaluable pts are ZAP70-positive. Based on the Binet and Rai staging systems 9 (10%), 25 (26%) and 24 (25%) of subjects are stage A, B and C, respectively; 7 (7%), 12 (13%) and 16 (17%) subjects are low, intermediate or high-risk disease, respectively. For 2 (2%) subjects the Binet/Rai staging is currently unknown. Overall, 19 pts (20%) received prior bendamustine-containing treatment and 71 pts (75%) received prior fludarabine-based treatment. The median number of prior therapies was 3 (range 1–10). Most common hematological grade ≥ 3 AEs include neutropenia (62%) and thrombocytopenia (34%). At baseline, 19% of pts presented with grade 1–2 neutropenia. The most common non-hematological ≥ grade 3 AEs include pneumonia (13%), tumor flare (13%), and fatigue (11%). TLS was reported in 3 pts (3%): grade 1, 3, and 4. In total, 8 grade 5 events were reported, 3 of which were suspected to be related to LEN: 2 cases of pneumonia and 1 death for unknown cause. At the time of the cut-off, 59 pts (62%) have discontinued treatment. Most common reasons for treatment discontinuation include disease progression (n = 20) and AEs (n = 20). To date, 47 pts (49%) have dose escalated above their starting dose levels of which 12 patients escalated to the highest dose level (25 mg daily). 18 subjects have had no dose level reduction or escalations and 1 patient is still in the first cycle of the study. Average duration of treatment is 6.5 cycles, and median number of cycles is 4. Efficacy evaluations are completed monthly after 3 months of study drug treatment. At time of the data reporting, 5 pts were on study drug but did not reach the first assessment at cycle. For the 90 pts evaluable for response, the investigator's assessment indicates 2 pts (2%) reached CR, 36 (40%) achieved PR, 33 (37%) patients had SD, and 19 (21%) pts progressed.

Conclusion:
The independent DMC, as of 14 June, 2012 (N=95), recommended that accrual into all three treatment arms should continue as planned, suggesting all three starting doses were well tolerated. To date, the ORR is 42% and 49% of pts were dose escalated at least once. In this rel/ref CLL population LEN appears active, and completion of accrual will clarify the appropriate dose at which to initiate therapy.

Disclosures:
Wendtner: Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Off Label Use: use of lenalidomie in relapsed/refractory CLL. Hallek:Celgene Corporation: Consultancy, Honoraria, Research Funding. Hillmen:Celgene Corporation: Honoraria. Gregory:Celgene Corporation: Honoraria, Research Funding. Stilgenbauer:Celgene Corporation: Honoraria, Research Funding, Speakers Bureau. Kipps:Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Purse:Celgene Corporation: Employment, Equity Ownership. Zhang:Celgene Corporation: Employment, Equity Ownership. Mei:Celgene Corporation: Employment.