Oral Clofarabine for Relapsed/Refractory Non-Hodgkin Lymphomas: Final Results from a Phase 1-2 Trial

• Published in: Blood 2014-12, Vol.124 (21), p.4423-4423
• Main Authors: Abramson, Jeremy S., Jacobsen, Eric D., Redd, Robert Allyn, Takvorian, Tak, Fisher, David C., Brown, Jennifer R., Schwartz, Joel H, Weitzman, James, Neuberg, Donna, Barnes, Jeffrey A., Hochberg, Ephraim P
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V124.21.4423.4423

Background: Clofarabine is a second-generation purine analogue FDA-approved as an intravenous formulation for relapsed/refractory pediatric ALL. Purine analogues demonstrate significant clinical activity in non-Hodgkin lymphomas (NHL). Clofarabine may offer pharmacologic advantages over other nucleoside analogues including being a more efficient substrate for deoxycytidine kinase, more completely inhibiting ribonucleotide reductase and DNA polymerase α, and demonstrating improved activity in cells that are non-dividing or have a low proliferation rate. This phase 1-2 trial studied an oral formulation of clofarabine in relapsed or refractory NHL. Methods: Patients were eligible if they had relapsed or refractory NHL of any histologic subtype. All pts were required to have adequate organ function and performance status ≤2 as well as absence of CNS involvement. Patients were treated at 4 dose levels (1mg, 2mg, 4mg and ultimately 3mg) with oral clofarabine administered once daily on days 1-21 of a 28 day cycle for up to 6 cycles. Three to 6 pts were treated at each dose level in a traditional 3+3 design followed by a 10 patient dose expansion at the recommended phase 2 dose (RP2D). The phase 1 portion of this study has been published (Leuk Lymph 2013; 45:1915-1920). Phase 2 was designed to enroll 24 additional subjects. The primary endpoint in phase 2 was overall response rate (ORR). Secondary endpoints were progression-free survival (PFS), overall survival (OS), and safety. A total of 50 patients were accrued on the phase 1-2 trial; 31 subjects were treated in phase 1 and 19 in phase 2. Phase 2 accrual was stopped prematurely due to discontinuation of the drug formulation used in the study. All patients treated at the RP2D (n=36) are included in the phase 2 efficacy analysis since there were no differences in treatment or follow-up for these patients. Results: The median age for all patients was 69 years (range 45-92). Eighty-two percent had advanced stage at study entry. The median number of prior regimens was 2 (range 1-7) and 4 patients had prior auto stem cell transplant. Histologies included follicular lymphoma (FL, 13 pts), small lymphocytic lymphoma (SLL, 8 pts), diffuse large B-cell lymphoma (DLBCL, 6 pts), marginal zone lymphoma (MZL, 11 pts), mantle cell lymphoma (MCL, 9 pts), T-cell lymphoma (TCL, 2 pts) and lymphoplasmacytic lymphoma (LPL 1 pt). The 3mg dose was declared the RP2D, as previously reported. The most common toxicities were anemia (78%