Clofarabine (CLO) Has Single Agent Activity in Relapsed and Refractory Non-Hodgkin Lymphoma (NHL) Including Rituximab (R)-Refractory Patients (pts).
Authors: Nabhan Chadi , Bitran Jacob David , Fried Walter , Galvez Angel G. , Magid Laura , Tolzien Kathy , Dewey Wendy , Venugopal Parameswaran 
Published: October 2019

Abstract
Abstract 921

Background:
CLO is a second generation nucleoside analogue with known activity in acute leukemia and myelodysplasia. As there is no standard therapy for refractory and transplant-ineligible relapsed NHL, and given the activity that purine analogues have in lymphoid malignancies, we sought to investigate the activity of CLO in this pt population regardless of histology.

Methods:
Eligible pts had measurable disease by CT and/or PET, ECOG performance status ≤ 2, and adequate renal, cardiac, liver, and bone marrow function (unless cytopenias were disease-related). CLO was given in the outpatient setting intravenously over 1-hour days 1-5 every 28 days for 6 cycles maximum. All pts received anti-viral and anti-pneumocystis jiroveci prophylaxis. First, we initiated a phase I portion using a standard 3×3 study design. CLO was given at 4 mg/m2 in cohort 1 with subsequent cohorts to be escalated by 2 mg/m2 each. Once the maximum tolerated dose (MTD) was determined, the phase II portion of this study was initiated at the MTD. All pts were followed until disease progression.

Results:
Thirty-three pts (18 females, 15 males) have been enrolled (7 in the phase I portion and 26 in the phase II), of which 29 are evaluable for response and/or toxicity (2 just started therapy, 1 taken off due to persistent cytopenias, and 1 withdrew consent). Median age was 69 years (range 27-88), median number of prior therapies was 3 (range 1-8), with 21% failing prior stem cell transplantation and 74% being R-refractory. Median time from original diagnosis to first CLO treatment was 36 months (range 6-216). Histologies included 12 diffuse large cell, 5 follicular, 5 small lymphocytic, 4 anaplastic large T-cell, and 1 each for Richter, mantle cell, marginal zone, peripheral T-cell, transformed, non-specific T-cell, and mixed histology. Median number of CLO cycles was 4 (range 1-6). Thrombocytopenia was the dose-limiting toxicity at 6 mg/m2 in 2/6 pts. The MTD recommended for phase II was 4 mg/m2. With a median follow up of 8 months (range 1-33), 7 pts (24%) showed complete response (CR) and 8 (27%) had partial response (PR) for an overall response rate of 51%. Four pts (13%) demonstrated stable disease and 10 (34%) showed progression. Median duration of response was 7 months (range 2-33+) with 6 pts continuing in remission including a patient who is undergoing stem cell transplantation. Median time to progression (TTP) was 3.5 months with median overall survival of 8 months. sEVEN pts (24%) remain progression-free. Of patients who were followed for more than 12 months, 60% were alive at 1-year. Five of the CR pts were of low-grade histology while only 2 had large cell lymphoma. All pts required growth factor support. Toxicity was mainly hematologic with 63% experiencing grade 3/4 thrombocytopenia, 60% grade 3/4 neutropenia, and 39% grade3/4 anemia, and 63%. Grade 3 and/or 4 non-hematologic toxicity included 2 (6%) with tumor lysis syndrome, 2 (6%) infectious episodes (pneumonia and bilateral cellulitis), 2 (6%) renal insufficiency, 2 (6%) fatigue, 1 (3%) seizure activity, 1 (3%) pleural effusion, and 1 hypokalemia (3%). No treatment-related mortality.

Conclusions:
CLO is active in heavily pre-treated B-cell NHL including R-refractory pts. Activity appears more pronounced in low-grade histology. The drug is well-tolerated and can be administered as an outpatient. Reversible myelosuppression is the major toxicity. Future studies in front-line in combination with R are warranted.

Disclosures:
Nabhan: Bayer: Honoraria, Research Funding, Speakers Bureau; Genzyme: Research Funding; Genentech: Honoraria, Speakers Bureau. Venugopal:Genzyme: Honoraria, Research Funding; Genentech: Honoraria, Research Funding, Speakers Bureau.