1083P - Peripheral Blood Stem Cell (PBSC) Mobilization and Engraftment after Brentuximab Vedotin Treatment in Anaplastic Large Cell Lymphoma (ALCL) Patients

Abstract

ABSTRACT Background Brentuximab vedotin is a CD30-targeted antibody conjugated to the microtubule-disrupting agent, monomethyl auristatin E (MMAE), by a protease-cleavable linker. In a pivotal phase 2 study (ClinicalTrials.gov NCT00866047), an objective response was achieved in 50 of 58 (86%) relapsed/refractory ALCL patients (pts) treated with brentuximab vedotin. More than half of the pts achieved a complete remission (CR) (59%), enabling some pts to subsequently receive a stem cell transplant (SCT) as consolidation. A retrospective evaluation was performed to characterize PBSC mobilization and engraftment following brentuximab vedotin treatment (tx). Methods Pts received 1.8 mg/kg brentuximab vedotin every 3 weeks as a 30-minute outpatient IV infusion for up to 16 cycles. Antitumor efficacy was based on response assessments by independent review according to Cheson 2007. Results Eight pts received autologous SCT as the first therapy after discontinuing tx with brentuximab vedotin in remission. PBSC collection was completed prior to initiation of brentuximab vedotin tx in 2 pts, and following brentuximab vedotin tx in 6 pts. These 6 pts achieved a best clinical response of CR with brentuximab vedotin tx. After brentuximab vedotin tx, PBSCs were mobilized using chemomobilization (n = 3 pts), plerixafor (n = 1), and granulocyte colony-stimulating factor alone (G-CSF) (n = 2). The number of CD34+ cells/kg obtained and the days of collection are shown in the table. The CD34 + /kg yield for each pt was greater than the standard target of ≥2.5 x 106, with a median of 7.0 x 106. All pts engrafted, and the median time to engraftment was 10.5 days (range 9–14) for neutrophils and 11.5 days (range 9–13) for platelets. The 100-day mortality rate post SCT was 0%. Conclusions Brentuximab vedotin does not appear to have a negative impact on the outcome of PBSC mobilization or engraftment in pts receiving high-dose therapy and auto SCT. Age Sex Cycles of B-V Mobilization Regimen Days Collected CD34+ Cells/kg (x 106) 46 M 4 IE/GCSF 1 46.9 57 F 8 IE/GCSF 2 7.1 61 M 7 plerixafor 4 4.1 41 F 8 GCSF 2 6.9 50 F 8 CED/GCSF 1 28.1 45 F 4 GCSF 2 4.0 IE = ifosfamide, etoposide CED = cyclophosphamide, etoposide, dexamethasone Disclosure A.R. Shustov: I have a consultancy relationship with and have received research funding from Seattle Genetics, Inc. I have also received honoraria from Millennium. J.D. Rosenblatt: Seattle Genetics, Inc. has provided research support to my institution. D.A. Kennedy: I am an employee of and have equity ownership in Seattle Genetics, Inc. M. Fanale: I have acted as a consultant and served on Advisory Board for Seattle Genetics, Inc. I have received honoraria and travel expenses from Seattle Genetics, Inc. Seattle Genetics, Inc. has also provided research funding to my institution.