Is It Safe to Continue Allogeneic Hematopoietic Cell Transplantation Via Cryopreservation During COVID-19 Pandemic?

s / Transplant Cell Ther 28 3S (2021) S1–S509 S263 Malignancies & Cellular Therapeutics, University of Kansas Medical Center, Kansas city, KS; 4 Department of Medicine, St Mary’s Medical Center, huntington, WV; 5 Division of Hematology and Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI Background: CD34+ graft cell dose (CD) has an imperative relationship to survival outcomes after allogeneic peripheral blood stem cell transplant (allo-PBSCT). A few studies have evaluated the effect of graft CD on outcomes after SCT. However, an optimal dose of CD34+ cells has yet to be defined. This systematic review and meta-analysis were performed to evaluate outcomes with graft CD in allo-PBSCT. Method: A total of 1744 records from 4 databases (PubMed, Embase, Cochrane, and Clinical trials.gov) were screened following the PRISMA guidelines, and ten studies reporting outcomes for varied graft CD in allo-PBSCT were included. Quality evaluation was done using the NIH quality assessment tool. The pooled analysis was done using the ‘metaXL’, and the random-effects model was used to estimate the pooled prevalence with 95% CI. The interstudy heterogeneity among the studies was assessed using the Q statistic proposed by Cochrane and the I2 index introduced by Higgins and Thompson. Results: A total of 3908 patients were included in this meta-analysis. The patients were grouped according to three graft CD variations: low dose (LD), optimal dose (OD), and high dose (HD) were defined as <3x106/kg, 4-8 x106/kg, and >8 x106/ kg, respectively. (Table 1) For dose-specific analysis, the patients who did not fall into each of the three groups were grouped as ‘others’. There were a total of 500, 388, and 132 patients in the LD, OD, and HD groups, respectively. The median age of patients was 42 (0.4-76) years. The pooled overall survival (OS) in the OD group after a median follow-up of 2.5 (1.4-3) years was 59% (96% CI 0.44-0.73, I2=85), while in LD and HD group was 55% (95% CI 0.380.71, I2=82) and 49% (95% CI 0.230.75, I2=81) at a median follow-up of 3 (2-3) years and 2 (2-3) years, respectively. The pooled prevalence of relapse in the OD group at the median follow-up of 3 (3-5) years was 35% (95% CI 0.28-0.42, I2=21). Only Yamamoto et al. reported relapse of 39% in the LD group at two years. The pooled prevalence of relapse-free survival (RFS) was 57% (95% CI 0.430.70, I2= 87) at the median follow-up of 2 (1.4-5) years in the OD group. The pooled incidence of acute graft versus host disease (GVHD) was 29% (95% CI 0.19-0.40, I2=61%) in the LD group while 43% and 30% in the OD and HD groups, as reported by Urbano et al. and Passweg et al., respectively. Conclusion: The OS was better in the OD group as compared to LD and HD groups. The relapse, RFS, and GvHD incidence could not be compared in different dose groups because of the scarcity of data. Further randomized prospective studies are the need of the hour to define the optimal dosing of graft cells.