Allogeneic hematopoietic stem cell transplantation in patients with prior infection caused by the sars-cov-2 (covid-19)

Topic: 22. Stem cell transplantation - Clinical Background: There are limited data on outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients with prior COVID-19. Aims: Our goal was to assess the outcomes of allogeneic HSCT in patients with prior COVID-19 infection. Methods: This single-center retrospective study included 54 adult patients who received allo-HSCT from July 2020 to September 2021 after previous COVID-19. The median age was 33 years (18–76), there were 30 (55.6%) females and 24 (44.4%) males. The underlying disease were AML (n=22, 40.8%), ALL (n=17, 31.5%), MDS (n=6, 11.1%), AA (n=4, 7.4%), CML (n=3, 5.5%) and HL (n=2, 3.7%). The median follow-up was 231 days (11 - 518). Control group included 122 patients without history of COVID-19 underwent allo-HSCT during the same period. The median age was 35 years (18 – 69) and the median follow-up time - 252 days (13 – 604). We assessed the cumulative incidence (CI) of neutrophil engraftment, acute/chronic graft-versus-host disease (GVHD) and also overall survival (OS), progression-free survival (PFS), relapse incidence (RI), non-relapse mortality (NRM). Results: The median time from COVID-19 onset to the diagnosis of underlying disease was 129.5 days (-183 - 5135). To the date of COVID-19 manifestation 23 (42.6%) patients were in remission of the underlying disease, 18 (33.3%) in relapse/ progression and remaining 13 (24.1%) had a simultaneous manifestation. The median time of COVID-19 onset since the last chemotherapy was 11 days (0 - 616). 26 patients required hospitalization due to SARS-CoV-2 infection (48.1%), 17 was outpatient (31.5%) and 11 – course of disease remains unknown (20.4%). The median time from COVID-19 to allo-HSCT was 211 days (31 - 447). None of the patients had recurrent COVID-19 during hospitalization. Due to HSCT date the standard risk patients represented the largest subgroup (n=40, 74.1%), followed by salvage risk subgroup of patients (n=14, 25.9%). Donors were haploidentical – 16 (29.6%), MUD – 16 (29.6%), MMUD – 11 (20.4%) and MRD – 11 (20.4%). The source of HSC: PBSC – 41 (75.9%) and BM – 13 (24.1%). RIC and MAC were used in 41 (75.9%) and 13 (24.1%) recipients, respectively. Majority of patients (n=48, 88.9%) received posttransplantation cyclophosphamide based GVHD prophylaxis. The CI of engraftment is 94.4% (95% CI 83,8 – 98,2%). The median time was 20 days (13 - 28). The CI of acute GVHD was 35,1% (95% CI 22,8 – 47,8%). The CI of chronic GVHD was 26,7% (95% CI 13,8 – 41,5%). The main complications of post-transplant period included venous thrombosis (n = 7, 12.9%), TMA (n=1, 1.85%), VOD (n=1, 1.85%), bloodstream infections (n=30, 55.5%), pneumonia (n=11, 20.3%), soft tissue infections (n=8, 14.8%), viral infections (n=30, 55.5%), invasive mycoses (n=6, 11.1%). The 200-day RI, NRM, OS and PFS were 9,7% (95% CI 3,6 – 19,7%), 14,8% (95% CI 7,0 – 25,6%), 78,4% (95% CI 64,2 – 87,4%) and 75,4% (95% CI 61,3 – 84,9%) respectively. The control group demonstrated the same short-term outcomes of allo-HSCT: 200-day RI – 10,3% (95% CI 5,6 – 16,7%), NRM – 17% (95% CI 10,8 – 24,3%), OS – 78,5% (95% CI 69,9 – 85%) and PFS – 72,6% (95% CI 63,5 – 79,8%). Summary/Conclusion: Allo-HSCT is feasible in patients with a history of COVID-19 and characterized by common post-transplant complications. The history of COVID-19 did not affect the 6 months results of allo-HSCT. Nevertheless, further studies are required in subgroups of patients with different consequences of COVID-19. Keywords: COVID-19, Allogeneic hematopoietic stem cell transplant