Spectrum Pharmaceuticals announced positive Phase 2 clinical data for Zevalin (ibritumomab tiuxetan) injection in patients with mantle-cell lymphoma (MCL).

According to the MCL study protocol, the trial enrolled individuals ≥18 years with Stage II-IV, histologically confirmed MCL (CD20+ and cyclin D1+) and no prior treatment. Fifty-two patients received initial therapy of four courses of RCHOP (consisting of rituximab [Rituxan; Genentech] with cyclophosphamide, doxorubicin [Adriamycin; Bedford Laboratories], vincristine [Vincasar PFS; Teva Pharmaceuticals], and prednisone), and, following no signs of disease progression, received first-line consolidation therapy with a Zevalin treatment regimen. The study design required 52 eligible patients to detect a 50% improvement in the median time to treatment failure (TTF) compared with that reported for six cycles of RCHOP.

The study showed that first-line consolidation with a Zevalin treatment regimen, following initial therapy consisting (RCHOP) given for four courses, was well tolerated and improved overall response rate (ORR= PR + CR) from 68% after RCHOP to 82% after Zevalin. The complete response rate (CR/CRu) improved from 19% after RCHOP to 56% after consolidation with Zevalin. Zevalin consolidation also met the primary endpoint of 50% prolongation of time to treatment failure (TTF) over that expected for R-CHOP x6 alone.  While there is no apparent plateau in TTF, median overall survival (OS) has not been reached, with an estimated 5-year OS of 73%.

Zevalin is a CD20-directed radiotherapeutic antibody. The Zevalin therapeutic regimen consists of two components: rituximab, and Yttrium-90 (Y-90) radiolabeled Zevalin for therapy. Zevalin builds on the combined effect of a targeted biologic monoclonal antibody augmented with the therapeutic effects of a beta-emitting radioisotope.

Zevalin injection for intravenous use is indicated for the treatment of patients with relapsed or refractory, low-grade or follicular B-cell non-Hodgkin’s lymphoma (NHL). Zevalin is also indicated for the treatment of patients with previously untreated follicular non-Hodgkin’s lymphoma who achieve a partial or complete response to first-line chemotherapy.

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