Impact of Time to Collection from Last Chemotherapy on Autologous Hematopoietic Stem Cell Transplant Outcome for Relapsed/Refractory Classical Hodgkin Lymphoma

Abstract

Background Immune reconstitution represented by lymphocytes recovery post autologous hematopoietic stem cell transplantation (HCT) has been shown to improve outcome in relapsed/refractory lymphoma. This in turn has been linked to the infused peripheral blood autograft absolute lymphocyte count (ALC). Shorter time from last chemotherapy to collection (CTC) has been found to negatively ALC at pre-pheresis and leads to poor outcome in relapsed diffuse large B cell lymphoma. We hypothesized that in relapsed/refractory classical Hodgkin lymphoma, CTC affects the ALC on the date of collection. Method Retrospective review of all adult patients who underwent autologous HCT (2007-2017) for histologically confirmed classical Hodgkin lymphoma at the Markey Cancer Center- University of Kentucky was done. Exclusion criteria included lack of salvage chemotherapy data, and those undergoing allogeneic HCT. Descriptive statistics were done for baseline characteristics. Median ALC was compared using Mann-Whitney U test. Kaplan-Meier curve with log rank testing was used to compare progression free survival (PFS) as well as overall survival (OS). Statistical analysis was done on SPSS 24. Results A total of 44 patients met the inclusion criteria. The median age was 34 (range 18-63) yrs. Male to female ratio was 2:1. The most common histology was nodular sclerosis (60%). The first line chemotherapy was ABVD in 83%. The most commonly used salvage regimens were Ifosfamide, Gemcitabine, and Vinorelbine (IGEV) in (55%) and Ifosfamide, Carboplatin and Etoposide (ICE) in (30%). Stem cell harvest was done from peripheral blood only using Cytoxan+GCSF (45%) and GCSF (18%). GCF+Plerixafor was used in 36% of the patients. Most of the patients (93%) collected a median of (5.5\u202f×\u202f106 CD 34 cells/kg) in 3 days. The Median CTC was 43 (range 26-91) days. Patients were then divided into two cohorts, Short CTC (6 weeks or less) and long CTC (more than 6 weeks). Baseline characteristics were balanced between the two groups (see table 1). There was no statistical difference in the median ALC (2.35 vs 1.47, p=0.226) (figure a), or CD34 cell count (6.06 vs 4.5, p=0.184) (figure b). At a median follow up time of 17 months (range 0-116 months), the progression free survival between the two groups were comparable (46 mo vs not reached, p=0.423) (figure c). Overall survival did not differ significantly (not reached for both groups, p=0.894) (figure d). Conclusion In our single institutional experience, time to collection of peripheral stem cell harvest did not affect ALC or outcome following salvage chemotherapy followed by autologous HCT in classical Hodgkin lymphoma. Other prognostic markers need exploration to improve outcome of relapse/refractory classical Hodgkin lymphoma.