ABSTRACT
Introduction: Randomized trials demonstrated ~95% efficacy of SARS-CoV-2 spike messenger RNA (mRNA) vaccines. Patients (pts) after allogeneic hematopoietic cell transplant (HCT) have a variable period of immune deficiency and the impact of diagnosis, treatment regimens, GvHD, and immunosuppression on vaccine (vacc) immunogenicity is unknown. Methods: We performed a retrospective analysis of 149 consecutive pts (Table) who received a SARS-CoV-2 vacc between 12/17/2020, and 5/21/21, and were tested for anti-SARS-CoV-2 S1/S2 antibodies. Serology testing was performed with the Liaison® SARS-CoV-2 S1/S2 IgG assay (DiaSorin) with ≥15 AU/mL defined as a positive result. Pts with prior COVID-19 infection were excluded. Pts received mRNA-1273/Moderna (n= 46), BNT162b2/Pfizer-BioNTech (n= 100) or Jannsen vacc (n= 3). Reactogenicity was not investigated. Demographic and treatment variables were tested for prediction of vaccine response using Chi-square test or Fisher's exact test for categorical variables and two-sample t test for continuous variables. Univariate and multivariable logistic regression analyses with backward selection using Akaike information criterion (AIC) were used to examine interdependence of those variables and odds ratios (OR) with 95% confidence intervals (CI). Results: Pts underwent HCT from a related HLA matched sibling (n=36), related haploidentical (n= 23), or matched/mismatched unrelated donor (n= 89). 93% received fludarabine in the HCT conditioning regimen (data not shown). All pts received a calcineurin inhibitor (CNI) and 76 pts received ATG for GvHD prophylaxis. All pts achieved at least mixed donor lymphoid engraftment (data not shown). Median time from HCT to 1st vaccination was 26 months (range, 3-258 months). Median age at time of vaccination was 61 years (range, 24-78) and 75 (50%) were female. Serology was tested at a median of 37 days (range, 6-119 days) after the second vacc dose. Serology was tested <14 days in 3 pts;all were seropositive. No pt developed COVID-19 during the period of observation. 101 pts (67%) tested positive for anti-SARS-CoV-2 S1/S2 antibodies (vacc responders). Of the responders, the median time from HCT to 1st vacc was 45.5 months (range, 3-258, SD 39.78). Among the 23 pts between 3-9 months after HCT, 26% (n=6) had a positive antibody response, but all were receiving ongoing immunosuppression at time of vaccination. 29% (n=29) vacc responders were receiving prednisone (pred) in the management of cGvHD at the time of vaccination. 48 pts did not mount an antibody response (vacc non-responders). Of the non-responders, 30 pts were receiving cGvHD treatment at the time of vacc, 31 pts were taking pred, and 20 pts were taking CNIs. In univariate analysis, we found a history of prolonged use of pred (>8 weeks) and/or CNIs, on current treatment for cGvHD at time of vacc, and receipt of rituximab in the preceding 12 months predicted for lack of response (Table). Active use of pred and treatment with pred >8 weeks in the preceding 12 months prior to vacc predicted vacc non-response [OR 0.221;95% CI (0.106 - 0.456);p<0.001] and [OR 0.408;95% CI (0.197 - 0.844);p=0.016] in univariate analysis, respectively, however, active use of pred was predictive [OR 0.07;95% CI (0.016-0.304;p<0.001] while pred treatment >8 weeks was not [OR 2.00;95% CI (0.55-7.298;p=0.293] in multivariable analysis. Other significant predictors for non-response in the multivariable analysis include pt use of ruxolitinib [OR, 0.233, 95% CI, (0.067-0.808);p=0.022], and rituximab within 1 year [OR, 0.026, 95% CI, (0.007-0.099);p<0.001]. Discussion: In this study, we found that 67% allogeneic HCT pts developed anti-SARS-CoV-2 S1/S2 antibodies after SARS-CoV-2 vaccination. Predictors of non-response after adjustment for potential confounders, were factors that are expected to suppress immune response including active use of immunosuppressive medications. Consistent with prior studies, anti-CD20 therapy likely impairs humoral response to vaccination. Ruxolitinib also appears to impair response. owever, a proportion of pts being actively treated for cGvHD responded to vaccination and these pts should still be encouraged to receive vaccination in consideration of the COVID-19 mortality risk. Many questions remain including the protective benefit of immune response, the duration of response, and the potential value of booster vaccinations in non-responders. [Formula presented] Disclosures: Rowley: ReAlta Life Sciences: Consultancy.
ABSTRACT
Background During 2020, the novel COVID-19 pandemic lead to cryopreservation of allogeneic hematopoietic stem cell (HSCT) grafts based on NMDP and EBMT recommendations, to secure grafts before start of conditioning chemotherapy. We examined the impact of this change in practice on patient outcomes. Methods We retrospectively analyzed the outcomes of 483 patients who received HSCT between Aug 2017 and Aug 2020, at Princess Margaret Cancer Centre, Canada, comparing the outcomes between those who received cryopreserved (CRYO, n=135) or fresh peripheral blood stem cell grafts (FRESH, n=348). Median follow-up: 12.3 months. Probability of overall survival (OS) was calculated using the Kaplan-Meier product-limit method and heterogeneity of time-to-event distribution functions were compared by the log-rank test. Cumulative incidences of aGvHD and cGvHD, relapse, and non-relapse mortality (NRM) were estimated using the cumulative incidence method considering competing risk, and groups were compared using Gray's test. Death was considered as a competing event for relapse, aGvHD and cGvHD, and relapse was considered a competing event for NRM, aGvHD and cGvHD. Results Median age was 58y;54.5% were males. Acute myeloid leukemia was commonest HSCT indication (n=248, 49.1%). Donors: MUD 10/10 n=233;MUD 9/10 (MMUD) n=48, matched related donor (MRD) n=112, Haploidentical n=88. Transplant conditioning: 79 (23%) and 23 (17%) patients received myeloablative conditioning (MAC) in the FRESH and the CRYO groups, respectively (p ns). In the FRESH group, 253 (73%) patients and 114 (84%) patients in the CRYO group received ATG followed by posttransplant cyclophosphamide (PTCy) and Cylosporine GvHD prophylaxis. OS at the 2y timepoint, FRESH group (n=348), was 67.0% (61.1-72.3%), compared to 48.7% (38.1-58.4%) for patients in the CRYO group (n=135), p=0.002, Figure 1a. This was mainly due to MRD cohort outcomes: 2y OS in MRD FRESH group (n=65), was 85.2% (73.3-92.0%), compared to 45.1% (29.9-59.1%) in MRD CRYO group (n=47), p<0.001, Figure 2a. Multivariate analysis (MVA) for OS, significant factors were increasing patient age, DRI high/v.-high, HCT-CI ≥ 3, Donors: Haplo and MMUD, cryopreservation, Table 1. NRM at 1y for FRESH (n=348) 17% (13.2-21.2) vs CRYO (n=135) 22.1 % (14.8-30.4), p ns. However, in the MRD cohort, NRM at 1y for FRESH group (n=65), was 1.5% (0.1-7.4%), compared to 15.4% (6.6-27.4%) for CRYO group (n=47), p=0.003, Figure 2b. On MVA, NRM adverse significant factors were patient age, DRI high/v.-high, Donors: Haplo and MMUD, Table 1. Cumulative incidence (CI) of relapse at 2y for FRESH 22.4% (17.5-27.7) vs CRYO 27.0 % (18.8-35.9) p=0.07. The CI of moderate-severe cGvHD at 1y for FRESH group (n=315) was 21.5% and 10.8% in the CRYO group, p=0.027, Figure 1c. Patients with FRESH 10/10 MUDs (n=180), had CI of moderate-severe cGvHD at 1y of 20.6%, compared to CRYO 10/10 MUDs (n=35), 6.0% p ns for MUDs;FRESH MRD (n=64) CI was 30.1%;and CRYO MRD (n=43) 10.3%, p=0.008 for MRD, Figure 1d. On MVA, significant adverse factors for chronic GvHD were increasing donor age, male recipient/female donor, whilst graft CRYO was protective, Table 1. GvHD-and Relapse free Survival (GRFS) at 2y for FRESH 54.0% (47.9-59.6) vs CRYO 43.4% (33.4-53.0) p<0.05, Figure 1b. However, in the MRD cohort, GRFS at 2y in FRESH group (n=65), was 74.2% (61.3-83.4%), compared to 40.7% (26.3-54.6%) for CRYO group (n=47), p=0.001;other donor types no difference, Figure 1c. On MVA, significant factors correlated with worse GRFS were: DRI high and very-high, cryopreservation, Donors: Haplo and MMUD, Table 1. Compared to FRESH group, CRYO group experienced reduced cGvHD, delay in neutrophil engraftment, higher graft failure and increased CMV reactivation, with no difference in relapse incidence or acute GvHD. Conclusion Cryopreservation was associated with inferior outcomes post-HSCT particularly in the MRD cohort, possibly due to combination ATG and post-transplant cyclophosphamide impacting differential tolerance to cryopreservation on components of the stem ce l graft;further studies are warranted to elucidate mechanisms for this observation. [Formula presented] Disclosures: Law: Novartis: Consultancy;Actinium Pharmaceuticals: Research Funding. Lipton: Bristol Myers Squibb, Ariad, Pfizer, Novartis: Consultancy, Research Funding. Kim: Bristol-Meier Squibb: Research Funding;Paladin: Honoraria, Research Funding;Pfizer: Honoraria, Research Funding;Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Mattsson: MattssonAB medical: Current Employment, Current holder of individual stocks in a privately-held company.