The U.S. Food and Drug Administration (FDA) has granted orphan drug designation to Cellectar BioSciences‘ experimental therapy CLR 131 for lymphoplasmacytic lymphoma (LPL), or Waldenström’s macroglobulinemia, a rare type of non-Hodgkin’s lymphoma.
This marks CLR 131‘s sixth orphan drug designation, having previously been awarded the status for five other cancer types, including multiple myeloma (in both the U.S. and Europe), neuroblastoma, rhabdomyosarcoma, Ewing’s sarcoma, and osteosarcoma.
Orphan drug designation is aimed at encouraging therapies for rare and serious diseases, and is granted to investigational therapies whose data supports high efficacy or safety compared with available treatments. The status allows manufacturers to qualify for various incentives, including seven years of market exclusivity, increased support from the FDA, and special fee exemptions and reductions.
“The orphan designation from the FDA for LPL represents the sixth for CLR 131 and underscores Cellectar’s commitment to develop therapies for rare cancers with limited treatment options and high unmet need,” James Caruso, president and CEO of Cellectar Biosciences, said in a press release.
CLR 131, a phospholipid-drug conjugate, is a small molecule designed to deliver radiation selectively to cancer cells while limiting the exposure of healthy cells. The therapy is essentially made of Cellectar’s small molecule CLR1404 — which targets specific lipid molecules in the membrane of cancer cells — bound to a radioactive compound called Iodine-131.
An ongoing Phase 2 trial, called CLOVER-1 (NCT02952508), is investigating CLR 131 in people with B-cell lymphomas who received prior treatment for their condition, including those with multiple myeloma, chronic lymphocytic leukemia/small lymphocytic lymphoma, lymphoplasmacytic lymphoma, marginal zone lymphoma, mantle cell lymphoma, and diffuse large B-cell lymphoma.
The open-label trial is recruiting patients — for a target enrollment of 80 participants — at approximately 10 cancer centers across the United States. Participants will receive a dose of 37.5 mCi/m2 of CLR 131 administered in two 30-minute infusions on the first and seventh days of the trial. Patients also have the possibility of receiving a second dose cycle 75 to 180 days later.
Its primary goal is to determine the proportion of patients achieving at least disease stabilization — a measure called clinical benefit response — after treatment with CLR 131.
Additionally, researchers hope to determine the efficiency of CLR 131 treatments by measuring the proportion of patients who respond to treatment, the amount of time patients live without the disease progressing, and overall survival.
Results from the first patients in the trial — who received a single 25 mCi/m2 dose of CLR 131, significantly lower than the newly adopted dose — showed that 33% of those with diffuse large B-cell lymphomas and 30% with multiple myeloma responded to treatment.
One patient with advanced lymphoplasmacytic lymphoma also had a 94% tumor reduction and a complete clearance of four of five masses.
“CLR 131 has demonstrated encouraging results in our ongoing Phase 2 CLOVER-1 trial in select B-cell lymphomas, which includes LPL patients,” Caruso said. “We look forward to sharing Phase 2 LPL clinical data in the near term.”
Top-line data from the trial is expected by March of this year.
