Abstract LB207: Continuous subcutaneous lenalidomide delivery improves the therapeutic index and avoids drug-related grade 3/4 hematologic toxicity in patients with relapsed/refractory multiple myeloma

Abstract Introduction: In a multiple myeloma mouse model (MM), we determined that subcutaneous (SC) continuous lenalidomide (Len) delivery demonstrated superior tolerability and efficacy to the active control Len given by daily i.p. over a 28 day cycle. Healthy volunteer studies showed that at a daily dose of 9.6 mg a day (400 mcg/h) the Len AUC0-24 was ∼60% less than that observed with an oral 25 mg Len dose. We hypothesized that this modality could improve Len’s therapeutic index by lowering the hematologic toxicity while maintaining or improving the efficacy. Methods: A phase 1b study in 2nd line or greater relapsed/refractory MM was performed to confirm the animal findings and determine if continuous Len can improve its therapeutic index with no negative impact on the cellular immune system. In brief, an RVd regimen was utilized wherein SC Len 9.6 mg/day was administered with an FDA registered ambulatory pump in a continuous fashion using a 28/28 day cycle. Patients were either trained to operate their pump and change the pre-filled cassettes at home or were managed in the clinic on M-W-F. All patients were seen in the clinic to receive weekly bortezomib 1.3mg/m2 and dexamethasone dosed weekly at 40/20mg, according to age. Patients who received bortezomib in a prior cycle were required to demonstrate sensitivity defined as durability for 6 months after discontinuation of the bortezomib. Results: Between September 2023 and November 2024, 6 relapsed/refractory MM patients were enrolled from 2 US community-based investigational sites in the phase 1b study. Median age was 73, male to female ratio 1/1, Caucasian 100%, and median lines of previous therapy were 2 (range 1-7). Two patients were refractory and 4 were relapsed to their prior treatment. Four patients were previously exposed to Len, one of which was discontinued from a prior regimen because of severe fatigue, and 6 had received prior bortezomib. Patients had received 3-12 cycles of study therapy. No drug-related grade 3/4 hematologic or non-hematologic toxicity occurred within cycle 1. No patients experienced drug-related anemia, neutropenia, leukopenia, or thrombocytopenia greater than grade 2 in up to 12 cycles of therapy. All 6 patients achieved an objective response (CR=1 / PR=5). One patient who achieved a partial response experienced grade 2 skin reaction during cycle 3 and withdrew from the study. Five patients are continuing treatment per protocol with a median PFS of > 10 mo. Len pharmacokinetics produced median steady-state blood levels (Cmax) of 39 ng/mL (range 26-94) (N=6) and were above the minimum target of 25 ng/mL. The Len regimen produced a median AUC0-24 of 921-1h*ng/ml (range 630-1503). Immune profiling did not show significant increases in immune checkpoint expression associated with T-cell exhaustion while CD19+ B cells were significantly depleted. Conclusion: Continuous delivery of low dose Len provides meaningful efficacy and improved tolerability with no grade >3 drug-related hematologic toxicity. Further studies in MM and chronic lymphocytic leukemia are planned. Citation Format: Nash Gabrail, Keith Lerro, Mohamad A. Hussein, Asher A. Chanan-Khan, Jamie C. Oliver. Continuous subcutaneous lenalidomide delivery improves the therapeutic index and avoids drug-related grade 3/4 hematologic toxicity in patients with relapsed/refractory multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB207.