FDA Grants Fast Track Status to Investigational Compound CLR 131 for DLBCL

Cellectar Biosciences’ investigational radiotherapeutic compound, CLR 131, has received fast track designation by the U.S. Food and Drug Administration (FDA) for the treatment of relapsed or refractory diffuse large B-cell lymphoma (DLBCL).

The designation will support and help expedite CLR 131’s clinical development, as well as its regulatory review and potential marketing approval in the United States.

“We are pleased to receive FDA’s fast track designation for CLR 131. This designation supports our efforts to more rapidly provide a new therapeutic option for patients with relapsed or refractory DLBCL, a disease that typically has a very poor prognosis and low rates of survival,” James Caruso, president and CEO of Cellectar, said in a press release.

CLR 131 is a small-molecule phospholipid-drug conjugate (PDC) that explores the tumor-targeting properties of lipid (fat) molecules to selectively deliver radiation to malignant cells. This targeted approach is expected to minimize radiation exposure to normal tissue and reduce toxicity.

The safety and efficacy of CLR 131 are being explored in the ongoing CLOVER-1 Phase 2 trial (NCT02952508) in patients with relapsed or refractory B-cell cancers, including multiple myeloma and lymphomas such as DLBCL. Patients must have relapsed or failed to respond to chemotherapy regimens containing Rituxan (rituximab) and an anthracycline.

CLOVER-1 is expected to enroll up to 80 patients (go here more information on contacts and locations). They will receive a 37.5mCi/m² dose of CLR 131 — given in two 18.75mCi/m² infusions on days 1 and 8 — with the option for a second dose 75 to 180 days later.

CLOVER-1’s main objective is to determine the proportion of patients achieving at least disease stabilization — a measure called clinical benefit rate — after a single administration of CLR 131.

Secondary measures include overall response rate, the time a patient lives without disease worsening, and overall survival.

“As announced last year, data from the DLBCL cohort in our ongoing CLOVER-1 trial showed an encouraging 33% overall response rate at the time of the interim assessment,” Caruso said.

These patients were receiving CLR 131 as their fourth-line treatment, and half achieved the primary measure of clinical benefit.

Responses have also exceeded expectations among other groups of patients, including those with chronic lymphocytic leukemia/small lymphocytic lymphoma, lymphoplasmacytic lymphoma, and marginal zone lymphoma, leading the company to expand the number of patients included in this cohort.

“We are optimistic that CLR 131 has the potential to provide a meaningful treatment option for these patients and look forward to additional data in 2019,” he said.

In addition to this study, CLR 131 is being evaluated in a Phase 1 trial (NCT02278315) in patients with relapsed or refractory myeloma, an indication for which the therapy has received FDA’s orphan drug status.

Cellectar is also recruiting for another Phase 1 trial (NCT03478462) to test the safety and early effectiveness of increasing doses of CLR 131 in children and adolescents with advanced brain cancer, solid tumors, and lymphoma.