CLR 131 Gets Orphan Drug Designation in Second Indication

Cellectar Biosciences has announced that the U.S. Food and Drug Administration (FDA) granted orphan drug designation to CLR 131 for the treatment of rhabdomyosarcoma, a rare pediatric cancer.

CLR 131 is the company’s lead Phospholipid Drug Conjugate (PDC) product candidate, and exploits the tumor-targeting properties of the company's proprietary phospholipid ether (PLE) and PLE analogs. It is the first potential therapy that would use a PDC tumor-targeting delivery platform to deliver a cytotoxic radioisotope (iodine-131) directly to malignant tumor cells.

“While initial response to treatment is generally favorable, there is an important need for new treatments, especially in children who experience relapse.” said John Friend, M.D., chief medical officer of Cellectar in a press release.

“Cellectar is committed to working closely with the FDA to fully evaluate the potential for targeted delivery of CLR 131 to address this currently unmet medical need.”

Rhabdomyosarcoma is the most common type of tissue sarcoma in children. It is a malignant tumor of mesenchymal origin, and accounts for an estimated 40% of childhood soft tissue sarcomas in the U.S.

According to the National Cancer Institute (NCI), approximately 340 new cases are diagnosed each year in North America, and the prognosis is favorable with a 64% 5-year survival in children aged birth to 19 years. At least one-third of all patients will experience disease progression or relapse, and 95% of all failures occur within 3 years. The median progression free survival following the first recurrence or progression is about 9 months.

Based on preclinical and interim Phase 1 study data, treatment with CLR 131 provides an original approach to treating solid and hematological tumors. The drug is being developed so that it can potentially provide patients with therapeutic benefits, including: overall survival (OS), an improvement in progression-free survival (PFS), surrogate efficacy marker response rate, and overall quality of life (QOL).

CLR 131 is currently being evaluated in a Phase 2 clinical study in relapsed or refractory (R/R) MM and a series of B-cell malignancies and a Phase 1 clinical study in patients with R/R MM to explore fractionated dosing. Later this year, the company plans to initiate a Phase 1 study with CLR 131 in pediatric solid tumors and lymphoma, and a second Phase 1 study in combination with external beam radiation for head and neck cancer.

In March, CLR 131 was granted Orphan Drug designation for the treatment of neuroblastoma, and earlier this month, it was granted Rare Pediatric Disease designation for the same indication.

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