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FDA grants CLR 131 Orphan Drug designation in lymphoplasmacytic lymphoma

Jan 7, 2020

On the 6th January 2020, CLR 131, an investigational small-molecule radio-therapeutic, was granted Orphan Drug Designation by the U.S. Food and Drug Administration (FDA) in lymphoplasmacytic lymphoma.1 CLR 131 is a phospholipid drug conjugate that selectively kills cancer cells by delivering cytotoxic radiation.

The Orphan Drug designation was based on the positive results from a multicenter phase II clinical trial (NCT02952508) CLOVER-1, which is evaluating the efficacy and safety of CLR 131 in select relapsed or refractory (R/R) B cell hematologic malignancies. Recently, released summary data from 20 heavily pre-treated patients, including 10 patients with R/R multiple myeloma (MM), and 10 with R/R B-cell lymphoma, who received a single dose of CLR 131, demonstrated a 30% overall response rate (ORR), with an average progression-free survival of 4.5 months, and an acceptable safety profile.2

In 2019, CLR 131 was granted Fast Track designation for the treatment of patients with R/R diffuse large B-cell lymphoma (DLBCL) based on an interim assessment of CLOVER-1 where patients with R/R DLBCL demonstrated an ORR of 33%.3 CLR 131 has also received Orphan Drug designation for the treatment of MM, neuroblastoma, rhabdomyosarcoma, Ewing’s sarcoma, and osteosarcoma. Additionally, CLR 131 is currently being evaluated in phase I studies in pediatric solid tumors and lymphoma, as well as MM.4

  1. Cellectar Biosciences. Cellectar Receives Orphan Drug Designation for CLR 131 in Lymphoplasmacytic Lymphoma (LPL). Press release; January 6 2020, [Accessed 07 January 2020]
  2. Cellectar online. Cellectar Reports Positive Phase 2 Interim Data for CLR 131 in Relapsed/Refractory DLBCL Patients. Published; July 18 2018, [Accessed 07 January 2020]
  3. Cellectar Biosciences. Cellectar Announces Data From 20 Patients Receiving a Single 25mCi/M2 Bolus Dose of CLR 131 in the Phase 2 CLOVER-1 Study. Press release; December 16 2019, [Accessed 07 January 2020]
  4. Multiple Myeloma Hub online. Top-line results from the phase II study of CLR 131 – CLOVER-1. Published; February 28 2019, [Accessed 07 January 2020]