LAUSR

Introduction Part B of the modified Magrath regimen (ifosfamide, etoposide, and cytarabine; IVAC) with or without rituximab (R) is utilized as a standalone regimen in the management of relapsed/refractory Burkitt lymphoma and other non-Hodgkin lymphomas (NHL). There are no comparative or prospective data and a paucity of retrospective, non-comparative data to support use of this regimen. A small retrospective study described second-line IVAC use without R in a mixed cohort of patients with diffuse large B-cell lymphoma (DLBCL) or peripheral T-cell lymphoma, suggesting utility as a bridge to hematopoietic cell transplantation (HCT) (Pereira J, et al. Leuk Res. 2006 Jun;30(6):681-5). The activity of this regimen in B-cell NHL, particularly in conjunction with R, and its toxicity remain incompletely described. In this study, we describe our institutional experience with IVAC +/- R in relapsed/refractory B-cell NHL. Methods We reviewed all patients with relapsed/refractory B-cell NHL treated with IVAC +/- R between 1 January 2004 and 30 September 2019 at Memorial Sloan Kettering Cancer Center to assess efficacy and toxicity. Patients who received IVAC as part of sequential or alternating chemotherapy were excluded. Standard dosing consisted of ifosfamide 1500mg/m2 IV over 60min days 1-5, etoposide 60mg/m2 IV over 60min days 1-5, cytarabine 2000mg/m2 IV over 3 hours every 12 hours days 1-2, with or without rituximab 375mg/m2 IV day 0 or 1 in 21- to 28-day cycles (Lacasce A, et al. Leuk Lymphoma. 2004 Apr;45(4):761-7). Results Cohort and treatment characteristics are described in Table 1. Among 54 eligible patients (median age 51 years), 76% had DLBCL; 30% had lymphomatous central nervous system involvement at the time of initiating IVAC. Patients had received median 2 prior lines of therapy, with the last dose of the most recent line of therapy administered a median of 3 weeks prior to initiating IVAC. Patients received median 2 cycles of IVAC +/- R; 48% received IVAC-R. Prophylactic antimicrobials with cycle 1 were utilized in 94%. Most patients received herpesvirus- (81%) and Pneumocystis- (80%) directed prophylaxis; broad-spectrum prophylaxis with a fluoroquinolone was less common (24%). Primary granulocyte colony stimulating factor (GCSF) was utilized in 93% of patients with cycle 1; primary or secondary GCSF was utilized in 94% of cycles. Efficacy outcomes are described in Table 1. Objective response rate (ORR) among 46 evaluated patients was 48%; 17% achieved CR. ORR did not vary significantly between patients who did or did not receive R (58% vs 42%; p = 0.5) but was associated with number of IVAC cycles administered (among responders, 69% received 3-4 cycles while 31% received 1-2 cycles; p < 0.001). At median follow-up of 22 months, median progression-free survival (PFS) and overall survival (OS) were 3.1 months and 4.9 months, respectively (Figure). In Cox proportional hazard regression analysis of survival, patients who received R with every cycle (p = 0.025) and received 3 or more cycles (p < 0.001) experienced significantly longer PFS. Patients who achieved CR (p < 0.001) or PR (p = 0.003), received R with every cycle (p < 0.001), received 3 or more cycles (p < 0.001), or underwent subsequent HCT or CAR-T cell therapy (p = 0.001) experienced significantly longer OS. Toxicity outcomes are described in Table 2. Grade ≥ 3 anemia (93%), neutropenia (94%), and thrombocytopenia (100%; all grade 4) were common, regardless of number of cycles received. Febrile neutropenia (FN) occurred in 65% of patients and complicated 47% of cycles; documented infection occurred in 44%. Risk of FN and infection did not appear to be influenced by use of antimicrobial or GCSF prophylaxis. Grade ≥ 3 elevations in AST/ALT or total bilirubin were uncommon (5.6% and 9.3%, respectively). Neurotoxicity attributed to cytarabine or ifosfamide occurred in 17% of patients and was usually low-grade; hemorrhagic cystitis occurred in one patient. In patients for whom cause of death was documented (n = 37), mortality was attributed to a treatment-related complication in 19%. Conclusion IVAC-R may be a useful bridging therapy for patients with relapsed/refractory B-cell NHL who are planned for HCT. However, its potential for profound hematologic toxicity and life-threatening complications despite prophylactic measures requires careful consideration of less toxic alternatives. Straus: Elsevier: Membership on an entity's Board of Directors or advisory committees, Other: CME writer; Targeted Oncology: Consultancy, Speakers Bureau; Imedex, Inc.: Speakers Bureau; NY Lymphoma Rounds: Consultancy; Takeda Pharmaceuticals: Research Funding, Speakers Bureau; Karyopharm Therapeutics: Membership on an entity's Board of Directors or advisory committees; OncLive: Speakers Bureau; ASH: Other: Conference in December 2019 on HL to other physicians during ASH; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees.