Fotemustine (MUFORAN) in Combination with Once Weekly Bortezomib and Dexamethasone (B-MuD): Good Clinical Activity and Favourable Toxicity Profile for Treatment of Relapsed Multiple Myeloma Patients.
Authors: Mangiacavalli Silvia , Pompa Alessandra , Pochintesta Lara , Pascutto Cristiana , Cocito Federica , Cazzola Mario , Corso Alessandro 
Published: October 2019

Abstract
Abstract 2957
Fotemustine (Muphoran), a nitrosourea alkylating agent approved for metastatic melanoma, and recently used in alternative autotransplant condition regimen (FEAM) for lymphoma patients, has proven to be active as single agent in Multiple Myeloma (MM) refractory-relapsed patients. Given the importance of reaching high-quality response even beyond frontline setting, and the proven activity of the proteasome inhibitor bortezomib + dexamethasone therapy, we explored by means of a phase I-II dose escalation study the feasibility and the efficacy of the three drug combination bortezomib (B) + fotemustine (Mu) + dexamethasone (D) (B-MuD) in MM patients (pts) relapsed after at least one therapy. The study has been approved by our local ethical committee; all pts signed written informed consent. Fotemustine was administered at two dose levels (80–100 mg/m2 i.v.) on day 1. The original 21-day schedule was early amended due to extra-hematological toxicity and a 35-day schedule was adopted (Bortezomib 1,3 mg/ m2 i.v. on days 1, 8, 15, 22, Dexamethasone 20 mg i.v. on days 1, 8, 15, 22) for a total of six courses. Twenty-four pts have been enrolled: M/F 13 (54%)/11(46%), median age 69 years (44–83), median number of previous therapies 2 (1–5). Previous treatments included autologous transplant in 13 pts (54%), bortezomib in 8 pts (33%), oral melphalan in 11 pts (46%) and thalidomide in 15 (63%). The MTD of Fotemustine was tested to be 100 mg/m2. Six pts dropped-out: 4 pts for extra-hematological toxicity, 2 for progression. The overall response rate was of 62% (CR 8%, VGPR 33%, PR 21%). Median time to first response was 36 days (range 21–83) with a median DOR of 19.4 months (95% CI 11.6–23.7 months). After a median follow-up of 24.3 months (range 1.6–32.8 months), the median OS was 28.5 months (95% CI 22.1-NR). The median TTP and the median PFS were 20.5 (95% CI 11.9–22.2 months) and 19.1 (95% CI 11.9–22.2) months respectively. Median time to next therapy (TNT) was 16.2 months (4–25.2). There was a correlation between response and PFS (p=0.0002). B-MuD resulted effective in patients previous exposed to bortezomib without difference in terms of response (p=0.25) and PFS (p=0.87) when compared to bortezomib-naive patients. As far as toxicity was concern, one-hundred and thirty-three AE of any grade were observed, 65 hematological (49%) and 68 (51%) non-hematological; Thrombocytopenia was the most common AE (32%) overall. Extra-hematological toxicity included neuropathy (23%), infections (14%), gastrointestinal symptoms (7%). Half of the events occurred during the first two cycles (49%), most were manageable, with 69% resolved or improved, 15% unchanged, 15% worsened. In conclusion B-MuD is effective and well tolerated in relapsed MM even in patients in advanced phase and previously exposed to several lines of therapies, including bortezomib.

Disclosures:
No relevant conflicts of interest to declare.