A Phase I Study of Bendamustine Combined with Lenalidomide and Dexamethasone in Patients with Refractory or Relapsed Multiple Myeloma.
Authors: Lentzsch Suzanne , O’Sullivan Amy , Lalo Silvana , Kruppa Carrie , Gardner Diane , Kennedy Ryan C , Burt Steve , Mapara Markus Y , Redner Robert , Roodman David , Volkin Robert L , Zonder Jeffrey 
Published: October 2019

Abstract
Abstract 1856
Poster Board I-882

Background:
Lenalidomide is an analog of thalidomide that has shown significant clinical activity in patients with relapsed or refractory multiple myeloma (MM), both as a single agent and in combination with dexamethasone. Bendamustine is a bifunctional alkylating agent that is approved for the treatment of chronic lymphocytic leukemia and indolent non-Hodgkin's lymphoma that has progressed during or relapsed within 6 months following a rituximab-containing regimen. Bendamustine combined with lenalidomide may be an effective treatment option for MM patients, particularly those with preexisting or bortezomib-induced neuropathy. Our primary objective was to determine the maximum tolerated dose (MTD) and safety profile of bendamustine and lenalidomide when administered with dexamethasone for patients with relapsed or refractory MM.

Methods:
Patients aged ≥18 years with confirmed, measurable stage 2 or 3 MM that was refractory to or progressed after 1 or more prior therapies, including lenalidomide, received bendamustine by intravenous infusion on days 1 and 2, oral lenalidomide on days 1–21, and oral dexamethasone on days 1, 8, 15, and 22 of each 28-day cycle. Treatment was continued until a plateau of best response, as determined by the IBMTR/ABMTR, was reached. Study drug doses were escalated through 4 levels (Table), with 3–6 patients enrolled at each level depending on the rate of dose-limiting toxicity (DLT). After determining the MTD, up to an additional 12 patients will be enrolled in an MTD expansion arm to better evaluate toxicity and clinical activity. Secondary endpoints included preliminary efficacy, as evidenced by objective response, time to disease progression, and overall survival.

Results:
To date, 11 patients have been enrolled, with a median age of 63 years (range, 38–75 years). The MTD of bendamustine and lenalidomide has not been identified at this point; currently, patients are enrolling on dose level 3 with 100 mg/m2 bendamustine and 10 mg lenalidomide. Thus far, DLT included 1 grade 4 neutropenia at dose level 2. Nine of 11 patients are currently eligible for response assessment. A partial response was observed in 67% of patients, including 1 very good partial response and 5 partial responses (PR). Two patients experienced stable disease and 1 exhibited progressive disease. Grade 3/4 adverse events included grade 3 neutropenia, thrombocytopenia, anemia, hyperglycemia, and prolonged QTC, and 1 grade 4 neutropenia.

Conclusions:
Bendamustine, lenalidomide, and dexamethasone form a well-tolerated and highly active regimen even in heavily pretreated MM patients, with a PR rate of 67%. Additional updates on response and MTD will be available at the time of presentation.

Disclosures:
Lentzsch: Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cephalon: Consultancy, Membership on an entity's Board of Directors or advisory committees. Off Label Use: Bendamustine is not FDA approved for the treatment of multiple myeloma in the USA. Burt:Millennium: Honoraria; Celgene: Honoraria. Mapara:Resolvyx: Consultancy, Research Funding; Genzyme: Membership on an entity's Board of Directors or advisory committees; Gentium: Equity Ownership; Celgene: Spouse is consultant , has received research funding, and participates on advisory board; Cephalon: Spouse has received funding for clinical trial and participates on advisory board. Redner:Biogen: Equity Ownership; Wyeth: Equity Ownership; Glaxo-Smith-Kline: Equity Ownership; Pfizer: Equity Ownership; Genzyme: Membership on an entity's Board of Directors or advisory committees. Roodman:Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy; Acceleron: Consultancy. Zonder:Amgen: Consultancy; Pfizer: Consultancy; Cephalon: Consultancy; Millennium: Consultancy, Speaking (CME only); no promotional talks.