Cellectar’s CLR 131 Shows Early Promising Survival Outcomes in Phase 1 Trial of Relapsed or Refractory Myeloma

Myeloma patients who received a single dose of the investigational therapy CLR 131 in an ongoing Phase 1 clinical trial have reached a median overall survival of 22 months, according to the drug’s developer, Cellectar Biosciences.

Cellectar is a clinical stage biotech developing phospholipid-drug conjugates (PDCs) for use in anti-cancer therapies. Phospholipids are a class of lipids, or fat molecules, and the major component of the cellular membrane. Cellectar creates PDCs by attaching a toxic payload to these lipid molecules.

The Phase 1 study (NCT02278315), currently enrolling participants, was designed to determine the safety and tolerability of CLR 131 in relapsed or refractory multiple myeloma patients.

Participants were included in one of four dose groups, or cohorts, to determine the best dosing regimen of CLR 131. Cohort 1 received the lowest dose, and the doses escalated to cohort 4, which received the highest dose.

Now, the company announced that patients included in the lowest-dose cohort lived for a median of 22.5 months. Those from the second and third cohorts lived for a median of 13.2 months and 6.7 months, respectively. But because the trial is still ongoing, the company expects that the median overall survival times will increase over time. The fourth cohort has been enrolled and results are expected later this year.

The promising results of this study have led to a second study, a Phase 2 trial for multiple myeloma patients, which is already recruiting participants. The study (NCT02952508) is also open to patients with other type B malignancies, including indolent chronic lymphocytic leukemia/small lymphocytic lymphoma; lymphoplasmacytic lymphoma; marginal zone lymphoma; mantle cell lymphoma; and diffuse large B-cell lymphoma.

The clinical trial, to be conducted in up to 15 cancer centers across the U.S., will evaluate patients’ response after a single infusion of CLR 131 at a defined dose of 25.0 mCi/m². Patients may be eligible for a second infusion administered 75 to 180 days after the first infusion.

Patients will also receive 40 mg of oral therapy with dexamethasone, a type of corticosteroid medication, each week for up to 12 weeks.

“We continue to make meaningful progress on our CLR 131 program and are encouraged by the observed clinical outcomes to date. We look forward to reporting data from the fourth cohort of our Phase 1 trial as well as the single and multi-dose Phase 2 study when available,” Jim Caruso, president and CEO of Cellectar Biosciences, said in a press release.

“We also continue to make progress evaluating the clinical utility of CLR 131 in both liquid and solid tumor orphan designated cancers that have potential for accelerated regulatory pathways,” he said.