Updated OS of patients with AL amyloidosis after CAEL-101.

Abstract

8026 Background: Morbidity and mortality remain high in immunoglobulin light chain (AL) amyloidosis due to organ involvement despite hematologic remission. Few anti-amyloid fibril therapies for AL amyloidosis exist. We previously published the results of the phase 1a/1b study of CAEL-101 in AL amyloidosis showing significant improvement in organ response rates.1 We report long-term outcomes. Methods: Patients enrolled in NCT02245867 with relapsed/refractory AL amyloidosis received in phase 1a, a one-time dose-finding CAEL-101 infusion and in phase 1b, 4 weekly CAEL-101 infusions with preplanned dose escalation. Patients were evaluated for organ response for 12 weeks after last infusion. We extracted clinical, laboratory, and pathology data regarding clinical course beyond 12 weeks after last treatment. We performed a review of all AL amyloidosis patients at our center not treated with CAEL-101 1/01/2012-12/30/19 as clinical comparisons. Results: 22 patients were enrolled in CAEL-101. 5 patients were treated in both phase 1a and phase 1b. With median follow-up of 81.3 months (IQR 60.4-87.7), long term follow-up data are available for 19/22 patients. 5 patients died during long term follow-up: 3 from progressive AL amyloidosis; 1 from organ transplantation complication; and 1 from venous thromboembolism sequelae. Among patients with organ data available, 10/17 had hematologic progression and received next line therapy. 5/17 patients had organ progression. All patients with organ PD had previous/concomitant hematologic PD. Median OS was not reached; median organ PFS was 93.3 months (38.9-NR). No delayed adverse events occurred. Comparison with historical control groups revealed trends toward improved OS: HR 0.42 (0.09-1.81 p=0.23) in all comers AL amyloid controls, and HR 0.20 (0.03-1.16 p=0.07) in cardiac controls. Kaplan-Meier analysis and Cox regression were performed. Conclusions: Patients with relapsed/refractory AL amyloidosis who received a low cumulative amount of the novel anti-amyloid CAEL-101 in a phase 1a/1b study had lengthy overall and progression-free survival compared to historical controls. Patterns of organ progression after initial response may reflect intrinsic differences in organ vulnerability. The CAEL101-301 and CAEL101-302 phase 3 clinical trials are underway to confirm these findings. Reference: 1. Edwards CV, Rao N, Bhutani D, et al: Phase 1a/b study of monoclonal antibody CAEL-101 (11-1F4) in patients with AL amyloidosis. Blood 138:2632-2641, 2021. [Table: see text]