Arcellx, Inc. announced that it has received notification from the U.S. Food and Drug Administration (FDA) that a clinical hold has been placed on its CART-ddBCMA investigational new drug (IND) for the treatment of patients with relapsed or refractory multiple myeloma (rrMM). The clinical hold was received on June 16, following a recent patient death. The company believes limitations on bridging therapy are a contributing factor and is working with FDA to amend the protocol to expand options for patients that are consistent with current clinical practice.

The FDA has provided clearance to Arcellx to continue to dose patients who have undergone lymphodepletion. iMMagine-1 is a Phase 2 pivotal, open-label, multicenter clinical trial designed to evaluate CART-ddBCMA, a BCMA-specific CAR-modified T-Cell therapy utilizing Arcellx's novel BCMA-targeted binding domain, for the treatment of adult patients with relapsed or refractory multiple myeloma. The primary objective of this study is to evaluate the overall response rate over a 24-month period.

In addition to safety, secondary endpoints include depth of disease response, duration of response, and overall survival over a 24-month period. Myeloma (MM) is a type of hematological cancer in which diseased plasma cells proliferate and accumulate in the bone marrow, crowding out healthy blood cells and causing bone lesions, loss of bone density, and bone fractures. These abnormal plasma cells also produce excessive quantities of an abnormal immunoglobulin fragment, called a myeloma protein (M protein), causing kidney damage and impairing the patient's immune function.

Multiple myeloma is the third most common hematological malignancy in the United States and Europe, representing approximately 10% of all hematological cancer cases and 20% of deaths due to hematological malignancies. The median age of patients at diagnosis is 69 years with one-third of patients diagnosed at an age of at least 75 years. Because MM tends to afflict patients at an advanced stage of life, patients often have multiple co-morbidities and toxicities that can quickly escalate and become life-endangering.