Cellectar Presents Data in Waldenstrom’s Macroglobulinemia in Poster at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting

On June 4, 2021 Cellectar Biosciences, Inc. (NASDAQ: CLRB), a late-stage clinical biopharmaceutical company focused on the discovery and development of drugs for the treatment of cancer, reported a poster at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual meeting (Press release, Cellectar Biosciences, JUN 4, 2021, View Source [SID1234583516]). In conjunction with the poster presentation, management will host a KOL call with the lead investigator for the company’s Phase 2 CLOVER-1 study of CLR 131 in patients with relapsed/refractory B-cell hematologic cancers, Dr. Sikander Ailawadhi, M.D. of the Mayo Clinic.

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The poster presentation entitled: Treatment Free Remission (TFR) and Overall Response Rate (ORR) Results in Patients with Relapsed/Refractory Waldenstrom’s Macroglobulinemia (WM) Treated with CLR 131 is an in-depth update of six patients from the company’s Phase 2a study of CLR 131 in Waldenstrom’s macroglobulinemia. To date, data have shown:

100% (6/6) overall response rate, 83.3% (5/6) major response rate and a 16.7% (1/6) complete response rate
Median time to initial response was 22 days after first infusion
Median time to major response, as defined as at least a 50% reduction in IgM, was 44 days after first infusion
Mean treatment free remission, as defined as the time from the last CLR 131 infusion to progression of disease, is 1.1 years and remains ongoing
Duration of response has not been reached, with 100% of the MYD88 wild type and high risk patients exceeding 8.5 months
Progression free survival (PFS) for both MYD88 wild type patients as well as the high-risk subgroup has not been reached after 18 months; PFS for multidrug refractory patients was 11 months
The most frequently reported treatment emergent adverse events were cytopenias
"CLR 131 is a differentiated targeted radiotherapy that has the potential to address patients with any mutational status, risk profile or multi-drug refractoriness in WM. Our pivotal study strategy will leverage these properties to address the treatment needs of patients, including the potential to provide durable response rates and meaningful treatment-free remission," said Dr. John Friend, chief medical officer at Cellectar. "CLR 131 has demonstrated impressive results including, to our knowledge, the only monotherapy to result in a complete response in this challenging WM patient set."

James Caruso, president and CEO of Cellectar added, "The data presented today from our ongoing Phase 2 CLOVER-1 study of CLR 131 in Waldenstrom’s further validates our clinical development program and gives us confidence in our goal of providing a new and better treatment with the potential to prolong and improve the quality of life for patients suffering from this devastating disease."

Management will host a conference call and webcast today, June 4, at 10:00 am ET featuring key opinion leader Dr. Sikander Ailawadhi. Dr. Ailawadhi is a Professor of Medicine, Lead, International Cancer Center, Division of Hematology/Oncology, Departments of Medicine and Cancer Biology at Mayo Clinic Florida. He was awarded the 2013 NCI Cancer Clinical Investigator Team Leadership Award as an Assistant Professor of Medicine at the USC Norris Comprehensive Cancer Center. Subsequently, he joined the Division of Hematology and Oncology at Mayo Clinic in Florida as a Senior Consultant in order pursue his career goal of clinical, translational and outcomes-based research in B-cell malignancies.

A replay of the call will be available on the Events page of company website following the live event.

About the Pivotal Trial of CLR 131 in Waldenstrom’s macroglobulinemia (WM)
The pivotal trial is designed as a global, non-comparator, single arm, expansion cohort of the currently ongoing Phase 2 CLOVER-1 study of CLR 131. The study will enroll 50 WM patients. Patients in the trial will receive up to four doses of CLR 131 over two cycles (cycle one days 1, 15, and cycle two days 57, 71). The primary endpoint of the trial is response rate as defined as a partial response (a minimum of a 50% reduction in the biological marker IgM) or better in patients that receive a minimum total body dose of 60 mCi with secondary endpoints of treatment free survival, duration of response and progression free survival. An independent data monitoring committee (iDMC) will perform an interim safety and futility evaluation on the first 10 patients enrolled. The assessment will occur patient by patient and will conclude after the tenth patient is evaluated; there is no planned study stoppage.

About Waldenstrom’s macroglobulinemia
Waldenstrom’s macroglobulinemia (WM) is a rare and incurable disease defined by specific genotypic subtypes that defines patient responses and long-term outcomes. The annual incidence is 6,500 with prevalence of approximately 60,000 patients globally. WM is a lymphoma, or cancer of the lymphatic system. The disease occurs in a type of white blood cell called a B-lymphocyte or B-cell, which normally matures into a plasma cell whose job is to manufacture immunoglobulins (antibodies) to help the body fight infection. In WM, there is a malignant change to the B-cell in the late stages of maturing, and it continues to proliferate into a clone of identical cells, primarily in the bone marrow but also in the lymph nodes and other tissues and organs of the lymphatic system. These clonal cells over-produce an antibody of a specific class called IgM.

WM cells have characteristics of both cancerous B-lymphocytes (NHL) and plasma cells (multiple myeloma), and they are called lymphoplasmacytic cells. For that reason, WM is classified as a type of non-Hodgkin’s lymphoma called lymphoplasmacytic lymphoma (LPL). About 95% of LPL cases are WM; the remaining 5% do not secrete IgM and consequently are not classified as WM.

There is no standard treatment for WM. Several drugs have demonstrated activity either alone or in combinations, but only a single drug has received regulatory approval. Treatment is mainly focused on the control of symptoms and the prevention of organ damage. Front-line treatments for WM include rituximab alone or in combination with other agents. In the salvage therapy (second line or later) setting, ibrutinib, combinations of proteosome inhibitors and immunomodulatory drugs and stem cell transplantation are considered. Ibrutinib is the only drug to receive regulatory approval (2015) as a salvage therapy; in late 2019, it was approved for front-line treatment in combination with rituximab. Factors such as long-term cytopenias, age, hyper viscosity, the need for quick disease control, lymphadenopathy, co-morbidities, and IgM-related end-organ damage are key consideration in the choice of treatment.