FDA Grants NX-5948 Fast Track Designation for R/R CLL, SLL

The Food and Drug Administration (FDA) has granted NX-5948, a Bruton’s tyrosine kinase (BTK) degrader, a Fast Track designation for adults with relapsed or refractory chronic lymphocytic leukemia (r/r CLL) or relapsed or refractory small lymphocytic lymphoma (r/r SLL) who previously received two lines of therapy, including a BTK inhibitor (BTKi) and a B-cell lymphoma 2 (BCL2) inhibitor, according to a news release issued by biopharmaceutical company Nurix Therapeutics, Inc.

The treatment is currently being evaluated in a Phase 1a/1b clinical trial, findings from which were presented at the 2023 American Society of Hematology (ASH) annual meeting. Researchers stated that the treatment “is safe and well tolerated and has clinical activity.”

According to the initial finding presented at ASH, NX-5948 had no dose-limiting toxicities or treatment-related side effects resulting in discontinuation of the treatment or reduction of the drug’s dosage, as well as no treatment-related serious side effects.

Researchers reported that the most common treatment-emergent side effects were purpura/contusion (57.1% of patients), nausea (35.7% of patients) and thrombocytopenia (35.7% of patients), with a 2.8-month median duration of treatment and nine out of 14 patients remaining on treatment.

“Fast Track designation for NX-5948 is an important recognition of the unmet patient need in CLL, particularly in the growing number of patients whose cancer has progressed following BTK and BCL2 inhibitor therapy,” Dr. Arthur T. Sands, president and chief executive officer of Nurix Therapeutics, Inc., said in the news release. “This designation follows encouraging safety and efficacy data from our ongoing phase 1 clinical trial, demonstrating early promise of clinical benefit with potential for durable outcomes. The receipt of Fast Track designation is especially timely given our plans to accelerate enrollment in the phase 1 trial of NX-5948 with the goal of enabling a pivotal study for NX-5948 as rapidly as possible.”

Fast Track designation, as the FDA explains on its website, “is a process designed to facilitate the development, and expedite the review of drugs to treat serious conditions and fill an unmet medical need. The purpose is to get important new drugs to the patient earlier.”

NX-5948, which is administered orally, degrades Bruton tyrosine kinase (BTK), which signals for cancer cells within B-cell malignancies to keep growing. Nurix Therapeutics, the manufacturer of the drug, announced in 2022 that the first patient had been treated in the trial evaluating NX-5948 in relapsed or refractory B-cell malignancies such as mantle cell lymphoma, chronic lymphocytic leukemia, non-Hodgkin lymphoma and others.

“We are excited to have initiated the trial of a second highly selective and potent BTK degrader, that has the additional feature of being able to cross the blood brain barrier,” Dr. Robert J. Brown, executive vice president of clinical development of Nurix Therapeutics, said in a press release issued at the time. “NX-5948 has the potential to offer a differentiated clinical profile for patients with relapsed or refractory B cell malignancies.”

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