Phase 2 CLOVER-1 Study Shows Promise for Patients with Triple Class Refractory Multiple Myeloma

Cellectar Biosciences announced that the open-label, phase 2 CLOVER-1 study, evaluating the efficacy and safety of CLR 131, showed a clinically meaningful 40% overall response rate (ORR) in a subset of patients with refractory multiple myeloma deemed triple class refractory who received a total administered dose of 60 mCi or greater.

The subset of patients who achieved the 40% ORR (n = 6) represents patients who were found to be triple class refractory and enrolled in part A of the CLOVER-1 study, as well as additional patients enrolled in part B from March through May 2020. Notably, all patients being enrolled in part B of the study are required to be triple class refractory.

The additional 6 patients were heavily pre-treated with an average of 9 prior multi-drug regimens. Moreover, 3 patients received a total administered dose of more than 60 mCi and 3 received less than 60 mCi.

“We remain encouraged by the consistency of CLR 131’s efficacy and tolerability data in these extremely challenging to treat triple class refractory multiple myeloma patients,” John Friend, MD, CMO of Cellectar Biosciences, said in a press release. “A 40% ORR is a clinically meaningful outcome. For reference purposes, 2 recently approved drugs received a 25% and 31% ORR in triple class refractory patients. We look forward to the further development of CLR 131, a first in class phospholipid radio conjugate that may provide a significant benefit to patients and treatment alternative for clinicians."

Consistent with data released in February 2020, patients receiving more than 60 mCi of CLR 131 have exhibited strong responses. Further, Cellectar Biosciences indicated patients continue to tolerate CLR 131 well, with the most common and almost exclusive treatment emergent adverse events (AEs) being cytopenias. Importantly, no unexpected AEs have been reported.

CLR 131 is currently being evaluated in 2 clinical studies. The CLOVER-1 phase 2 study already completed the part A dose-exploration portion, conducted in relapsed/refractory B-cell malignancies, and is now enrolling in the part B expansion cohorts evaluating a 2 cycle dosing regimen that provides an approximately 100 mCi total body dose of CLR 131 in relapsed or refractory multiple myeloma and lymphoplasmacytic lymphoma/Waldenstrom’s macroglobulinemia.

Data from the part A portion of CLOVER-1 was announced on February 19, 2020.

An open-label, sequential group, dose-escalation phase 1 pediatric study is also being conducted to evaluate the safety and tolerability of CLR 131 in children and adolescents with relapsed or refractory cancers, including malignant brain tumors, neuroblastoma, sarcomas, and lymphomas (including Hodgkin’s lymphoma). The study is being conducted internationally at 7 leading pediatric cancer centers.

The FDA granted CLR 131 fast track designation for both relapsed or refractory multiple myeloma and relapsed or refractory diffuse large B-cell lymphoma, as well as orphan drug designation for the treatment of multiple myeloma, lymphoplasmacytic lymphoma/Waldenstrom’s macroglobulinemia, neuroblastoma, rhabdomyosarcoma, Ewing’s sarcoma, and osteosarcoma. CLR 131 was also granted rare pediatric disease designations for the treatment of neuroblastoma, rhabdomyosarcoma, Ewing’s sarcoma, and osteosarcoma.

Earlier this year, the European Commission granted an orphan drug designation for relapsed or refractory multiple myeloma and most recently, the FDA granted fast track designation for CLR 131 in lymphoplasmacytic lymphoma/Waldenstrom’s macroglobulinemia in patients having received 2 prior treatment regimens or more.

Reference:

Cellectar Reports Data on CLR 131 Phase 2 CLOVER-1 Study in Triple Class Refractory Multiple Myeloma Patients [news release]. Florham Park, NJ. Published September 9, 2020. Accessed September 9, 2020. https://www.globenewswire.com/news-release/2020/09/09/2090856/0/en/Cellectar-Reports-Data-on-CLR-131-Phase-2-CLOVER-1-Study-in-Triple-Class-Refractory-Multiple-Myeloma-Patients.html