Summary data from 20 patients receiving a single dose of CLR 131 in the phase II CLOVER-1 trial in select relapsed/refractory (RR) B-cell malignancies has been reported. Investigators previously announced data from 10 multiple myeloma patients receiving a single dose of CLR 131 in February 2019, which showed a 30 percent overall response rate (ORR).
The CLOVER-1 study is designed to identify a safe and efficacious dose and regimen to be used in a pivotal study for select hematologic indications. The 20 evaluated patients included 10 subjects with relapsed/refractory multiple myeloma, and 10 with relapsed/refractory B-cell lymphoma. The median age was 71 (range 52-82), including seven females and 13 males, with a median of six prior systemic therapies for multiple myeloma and four for patients with lymphoma. Eight patients had prior autologous stem cell transplant therapy. Data from these 20 patients showed a 30 percent ORR, a 75 percent clinical benefit rate, an average progression-free survival of 4.5 months, and an acceptable and expected safety profile.
The primary adverse events (AEs) seen were cytopenias, including thrombocytopenia, anemia, neutropenia, and decreased white blood cell count. The hematologic AEs were expected, manageable, and followed a predictable timeline to nadir (average 49 days) and subsequent recovery (average 16 days post nadir). Patients with disease in the bone marrow experienced more cytopenias than did patients with no detectable disease in the bone marrow. All patients recovered from the cytopenias.
CLOVER-1 is a phase II study of CLR 131 being conducted in approximately 10 leading cancer centers in the U.S. in patients with relapsed or refractory B-cell hematologic cancers. The hematologic cancers being studied in the trial include multiple myeloma, chronic lymphocytic leukemia/small lymphocytic lymphoma, lymphoplasmacytic lymphoma, marginal zone lymphoma, mantle cell lymphoma, and diffuse large B-cell lymphoma.
The study will enroll up to 80 patients. Its primary endpoint is clinical benefit response, with additional endpoints of overall response rate, progression free survival, median overall survival, and other markers of efficacy following a fractionated dose of 37.575mCi/m2 of CLR 131 administered in two 30-minute infusions of 18.75mCi/m2 of CLR 131 administered on day 1 and day 7 (± 1), with the option for a second dose cycle approximately 75-180 days later.