ALBERT

Description: Introduction: The role of T cell receptor (TCR) γδ cells in allogeneic hematopoietic stem cell transplantation (HSCT) is becoming of increasing interest1,2. In contrast to conventional alloreactive TCR αβ cells, TCR γδ cells are believed to have anti-tumor effects without causing graft-versus-host disease (GVHD). We conducted a single-center, prospective study to assess the impact of early TCR γδ cell immune reconstitution on overall survival, relapse and acute GVHD after HSCT. Methods: From October 2015 to March 2017, 108 consecutive patients transplanted for malignant diseases at the Bone Marrow Transplant Unit, Department of Hematology, Copenhagen University Hospital, Rigshospitalet, were included in the study, table 1. Fresh blood samples days 28, 56, 91, 180 and 360 after transplantation were analyzed for absolute concentrations of CD3-, CD4- and CD8 positive T cells together with a multi-color flow cytometry panel with staining for TCRαβ, TCRγδ, Vδ1, Vδ2, CD3, CD4, CD8, HLA-DR, CD196, CD45RO, CD45RA, CD16, CD56, CD314 (NKG2D) and CD337 (NKp30) for immune phenotyping. Results: After a median of 673 (386-913) days, 28 (26%) patients had died from relapse (n=14) and from transplant-related-mortality(n=14), respectively. A total of 24 (22%) patients experienced relapse during the observation time with median time to relapse of 177 (56-778) days. Acute GVHD grade 2-4 was diagnosed in 38 (35%) of patients. Patients were divided into two groups by dichotomization at the median value of TCR γδ cell concentrations for Kaplan-Meier analyses of overall survival (OS), relapse-free survival (RFS) and cumulative incidence analyses (Gray's test for competing risks) of relapse and acute GVHD. Patients with high concentrations of TCR γδ cells 56 days after transplantation had significantly higher OS and RFS compared with patients with low concentrations, p

Description: Introduction One third of patients with myelodysplastic syndrome (MDS) will relapse after allogeneic stem cell transplantation (SCT), with a dismal prognosis. Early detection of relapse enables pre-emptive treatment and may potentially reduce relapse risk, but is limited by the lack of sensitive markers for minimal residual disease (MRD). We developed a pipeline where patient-specific mutations, as determined by a myeloid next generation sequencing (NGS) panel are tracked using sensitive digital droplet PCR (ddPCR). Method We designed a prospective Nordic study (NMDSG14B; NCT02872662) enrolling all patients with MDS, mixed MDS / MPN or AML with myelodysplasia related disease and 〈 30% marrow blasts undergoing SCT in the Nordic region. We hypothesized that personalized MRD detection by ddPCR can predict clinical relapse earlier than conventional methods. Patients were included before SCT and serial bone marrow samples were collected before, and 1 and 3 months post SCT, and thereafter every third month for 2 years or until relapse or death. Blood samples were collected monthly. The MRD results were not available for the treating physicians. MRD positivity was defined based on the background noise of the specific ddPCR-assays and varied between 0.05-0.1% VAF. Results Three-hundred and sixteen patients were screened between 2016 and 2020, of which 19 were excluded due to lack of mutation or disease progression preventing SCT. We here present data of 254 patients followed ≥ 6 months after SCT. Median age was 64 (18-78) years and 59% were male. Most WHO subgroups of MDS (n=166), MDS/MPN (n=39), AML (n=8) and therapy-related disease (n=41), were represented. Risk profile according to IPSS-R was very low (n=13), low (n=32), intermediate (n=46), high (n=60) and very high (n=32). The majority of patients received pre-SCT treatment consisting of HMA (n=159) and / or intensive chemotherapy (n=59) while 60 patients did not receive disease-modifying treatment prior to SCT. The most common mutations were ASXL1 (n=69), TET2 (n=58), SRSF2 (n=57) and TP53 (n=44). No mutation was identified in 10 pts, and NGS data is still pending for 11 patients. After a median follow-up of 436 days, estimated 2 years overall survival and relapse free survival were 72% and 63%, respectively. Cumulative incidence of NRM and relapse at 2 years was 16% and 20%, respectively. Forty-six patients relapsed after a median of 170 (53-733) days, and the estimated median survival following relapse was 197 days. The most common pre-SCT mutations in the relapsed cohort were TP53 (n=19), DNMT3A (n=11) and RUNX1 (n=9). Thirty-seven patients died due to non-relapse mortality (NRM) after a median of 83 (4-754) days. To date, MRD results are available for 64 patients. Relapse was preceded by positive MRD in 14 out of 15 patients a median of 79 (21-173) days before clinical relapse. The 15th patient had an extra-medullary relapse only. Borderline positive MRD samples 〈 0.2% VAF within 100 days after SCT followed by negative samples were seen in 11 non-relapse patients. Twenty-four of 37 patients in continuous complete remission (CCR) were consistently MRD neg. Six CCR patients had positive MRD after 100 days; two with transient borderline peaks ( 0.1%, which turned negative when the patients developed GVHD; one patient with slowly decreasing MRD which turned negative first after 1 y, and finally one patient with prevailing KIT mutation (〉700 days post-SCT) despite negative BCOR and STAG2. Two MRD+ patients died from NRM without showing signs of clinical relapse. Discussion In summary, we show that our pipeline of personalized MRD-assessment, based on patient-specific mutations is feasible with a high sensitivity to predict relapse. An update of study progression will be presented at the meeting. Figure 1 Disclosures Illman: Sanofi-Genzyme: Other: Travel Support; Celgene: Other: Travel Support. Mielke:DNA Prime: Honoraria, Other: received via my institution , Speakers Bureau; KIADIS Pharma: Honoraria, Other: received via my institution , Speakers Bureau; Miltenyi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: received via my institution , Speakers Bureau; Kite/Gilead: Honoraria, Other: received via my institution , Speakers Bureau; Bellicum: Honoraria, Other: received via my institution, Speakers Bureau; Novartis: Honoraria, Other: received via my institution, Speakers Bureau; Celgene/BMS: Honoraria, Other: received via my institution , Speakers Bureau. Ebeling:Accord Healthcare: Other: Travel Support; Amgen: Other: Travel Support; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; Otsuka Pharma Scandanavia AB: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Description: Introduction: Suppression of tumorigenicity 2 (ST2) is a prognostic plasma marker of non-relapse mortality (NRM) after allogeneic hematopoietic cell transplantation (allo-HCT) when measured at day +14 [Vander Lugt MT et al., N Engl J Med, 2013] and at day +7 in combination with regenerating islet-derived 3α (REG3α) [Hartwell MJ et al., JCI Insight, 2017]. We hypothesized that also pre-transplantation ST2 levels would be associated with NRM in the first 6 months after allo-HCT. Methods: We studied 112 adult patients who underwent allo-HCT with myeloablative conditioning at Rigshospitalet between July 2015 and August 2018 (Table 1). ST2 levels were measured by enzyme-linked immunosorbent assays using stored EDTA plasma samples obtained at the patients' scheduled pre-transplantation visit around day -23 (±11 days) and post-transplantation at days +7 and +14 (±3 days, n = 76 and 66). Univariable linear models and Spearman's ρ were used to evaluate associations and correlations between pre-transplantation ST2 levels and patient characteristics and other prognostic markers, respectively. Cause-specific Cox regression models were used to estimate hazard ratios (HR) with 95% confidence intervals (CI) for NRM in the first 6 months after allo-HCT (relapse as competing risk) and grade II-IV acute graft-versus-host disease (GvHD) in the first 100 days after allo-HCT (NRM and relapse as competing risks) according to pre-transplantation ST2 levels. Gray's test was used to test differences in the cumulative incidence of NRM in the first 6 months after allo-HCT according to quartiles of pre-transplantation ST2 levels. Results: The median pre-transplantation plasma ST2 level was 19.9 ng/mL (inter-quartile range: 14.6-25.7 ng/mL, Figure Panel A); levels were higher in males (β = 8.7 ng/mL, p 〈 0.01), but did not differ by age (p = 0.81) or by being transplanted for acute leukemia (p = 0.89). ST2 was correlated with C-reactive protein (ρ = 0.24, p = 0.01), the endothelial activation and stress index (EASIX, calculated as creatinine x lactate dehydrogenase/thrombocytes, ρ = 0.27, p 〈 0.01) and ferritin (ρ = 0.28, p 〈 0.01). Longitudinally, pre-transplantation ST2 levels were strongly correlated with ST2 levels on day +7 (ρ = 0.57, p 〈 0.01) and day +14 (ρ = 0.48, p 〈 0.01). The cumulative incidence of NRM at 6 months was 11% (n = 12); causes of death were organ failure (75%), acute graft-versus-host disease (GvHD, 17%) and infection (8%). Higher pre-transplantation ST2 levels were associated with increased hazard of NRM in the first 6 months after allo-HCT (HR 1.73 per 10 ng/mL increase, 95% CI: 1.28-2.33, p 〈 0.01, area under the receiver operating characteristics curve = 0.61). Despite a significantly higher NRM in patients with pre-transplantation ST2 levels in the highest quartile (cumulative incidence at 6 months: 21% vs. 7% in patients with levels in the three lower quartiles, p = 0.03), there was no overall significant difference in NRM according to quartiles of pre-transplantation ST2 levels (p = 0.15, Figure Panel B). No significant association was found between pre-transplantation ST2 levels and grade II-IV acute GvHD (HR 0.88, 95% CI: 0.61-1.26, p = 0.48). Conclusion: Pre-transplantation ST2 levels were associated with increased NRM in the first 6 months after myeloablative allo-HCT, mainly driven by higher NRM in patients with pre-transplantation ST2 levels in the highest quartile. Larger studies are warranted to validate pre-transplantation ST2 levels as a prognostic marker of NRM after allo-HCT, which potentially could be used to support the choice of conditioning intensity. Disclosures No relevant conflicts of interest to declare.