Cellectar Reports Data on CLR 131 Phase 2 CLOVER-1 Study in Triple Class Refractory Multiple Myeloma Patients

40% overall response rate (ORR) with a total administered dose of 60 mCi or greater

FLORHAM PARK, N.J., Sept. 09, 2020 (GLOBE NEWSWIRE) -- Cellectar Biosciences, Inc. (NASDAQ: CLRB), a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of drugs for the treatment of cancer, today announced that a clinically meaningful 40% overall response rate (ORR) was observed in the subset of refractory multiple myeloma patients deemed triple class refractory who received a total administered dose of 60 mCi or greater. Triple class refractory is defined as patients refractory to immunomodulatory, proteasome inhibitors and anti-CD38 antibody drug classes.

The 40% ORR (6/15 patients) represents triple class refractory patients enrolled in Part A of Cellectar’s CLOVER-1 study and additional patients enrolled in Part B from March through May 2020. As a reminder, all patients being enrolled in Part B are required to be triple class refractory. The additional six patients were heavily pre-treated with an average of 9 prior multi-drug regimens. Three patients received a total administered dose of greater than 60 mCi and three received less than 60 mCi. Consistent with the data released in February 2020, patients receiving greater than 60 mCi exhibit strong responses. Patients continue to tolerate CLR 131 well, with the most common and almost exclusive treatment emergent adverse events being cytopenias and importantly, no unexpected adverse events have been reported.

“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,” said Dr. John Friend, CMO of Cellectar Biosciences. “A 40% ORR is a clinically meaningful outcome. For reference purposes, two 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."

About CLOVER-1
The Phase 2 CLOVER-1 study is an open-label study designed to determine the efficacy and safety of CLR 131 in select B-cell malignancies. The CLOVER-1 Phase 2 study completed the Part A dose-exploration portion, conducted in relapsed/refractory (r/r) B-cell malignancies, and is now enrolling in the Part B expansion cohorts evaluating ≥ 60 mCi total body dose and 2 cycle doses as patients have demonstrated a clinically meaningful response and predictable safety profile of CLR 131 in r/r multiple myeloma (MM) and lymphoplasmacytic lymphoma/Waldenstrom’s macroglobulinemia (LPL/WM). Patients with LPL/WM must have received at least two prior treatment regimens, unless ineligible to receive standard agents, and have measurable disease, as defined by either a nodal lesion of >15 mm, an extranodal lesion of >10 mm, or measurable IgM. Prior external beam radiation therapy was allowed. The median age of the four LPL/WM patients enrolled in the study was 70 (range 54-81) and included 2 females and 2 males who had a median of two prior regimens (range 1-5). CLR 131 was administered intravenously, up to 30 minutes.