Impact of fludarabine and treosulfan on ovarian tumor cells and mesothelin chimeric antigen receptor T cells.

In addition to their immunosuppressive effect, cytostatics conditioning prior to adoptive therapy such as chimeric antigen receptor (CAR) T cells may play a role in debulking and remodeling the tumor microenvironment. We investigated in vitro the killing efficacy and impact of treosulfan and fludarabine on ovarian cancer cells expressing mesothelin (MSLN) and effect on MSLN-targeting CAR T cells. Treosulfan and fludarabine had a synergetic effect on killing of SKOV3 and OVCAR4 cells. Sensitivity to the combination of treosulfan and fludarabine was increased when SKOV3 cells expressed MSLN and when OVCAR4 cells were tested in hypoxia, while MSLN cells surface expression by SKOV3 and OVCAR4 cells was not altered after treosulfan or fludarabine exposure. Exposure to treosulfan or fludarabine (10 µM) neither impacted MSLN-CAR T cells degranulation, cytokines production upon challenge with MSLN + OVCAR3 cells, nor induced mitochondrial defects. Combination of treosulfan and fludarabine decreased MSLN-CAR T cells anti-tumor killing in normoxia but not hypoxia. In conclusion, treosulfan and fludarabine killed MSLN + ovarian cancer cells without altering MSLN-CAR T cells functions (at low cytostatics concentration) even in hypoxic conditions, and our data support the use of treosulfan and fludarabine as conditioning drugs prior to MSLN-CAR T cell therapy.

CAR T cells and T cells phenotype and function are impacted by glucocorticoid exposure with different magnitude.

BACKGROUND: Chimeric antigen receptor (CAR) T cell therapy is associated with high risk of adverse events. Glucocorticoids (GCs) are cornerstone in the management of high-grade cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Given the potentially deleterious effects of GCs on CAR T cells anti-tumor activity, increasing our understanding of GCs impact on CAR T cells is crucial. METHODS: Using several CAR T cells i.e., CD19, mesothelin (MSLN)-CD28 and MSLN-41BB CAR T cells (M28z and MBBz), we compared phenotypical, functional, changes and anti-tumor activity between i) transduced CD19 CAR T cells with untransduced T cells, ii) M28z with MBBz CAR T cells induced by Dexamethasone (Dx) or Methylprednisolone (MP) exposures. RESULTS: Higher levels of GC receptor were found in less differentiated CAR T cells. Overall, Dx and MP showed a similar impact on CAR T cells. Compared to untreated condition, GCs exposure increased the expression of PD-1 and TIM-3 and reduced the expression of LAG3 and function of T cells and CAR T cells. GC exposures induced more exhausted (LAG3 + PD1 + TIM3 +) and dysfunctional (CD107a-INFγ-TNF-IL2-) untransduced T cells in comparison to CD19 CAR T cells. GC exposure impaired more CD4 + than CD8 + CD19 CAR T cells. GC exposures increased more PD-1 expression associated with reduced proliferative capacity and function of M28z as compared to MBBz CAR T cells. CAR T cells anti-tumor activity was greatly affected by repeated GC exposure but partly recovered within 48h after GCs withdrawal. CONCLUSIONS: In summary, GCs impacted phenotype and function of untransduced and CAR T cell with different magnitude. The nature of the CAR costimulatory domain influenced the magnitude of CAR T cell response to GCs.

Flow cytometry-based measurable residual disease (MRD) analysis identifies AML patients who may benefit from allogeneic hematopoietic stem cell transplantation.

Measurable residual disease (MRD) monitoring independently predicts long-term outcomes in patients with acute myeloid leukemia (AML). Of the various modalities available, multiparameter flow cytometry-based MRD analysis is widely used and relevant for patients without molecular targets. In the transplant (HCT) setting, the presence of MRD pre-HCT is associated with adverse outcomes. MRD-negative remission status pre-HCT was also associated with longer overall (OS) and progression-free survival and a lower risk of relapse. We hypothesize that the combination of disease risk and MRD at the time of first complete remission (CR1) could identify patients according to the benefit gained from HCT, especially for intermediate-risk patients. We performed a retrospective analysis comparing the outcomes of HCT versus non-HCT therapies based on MRD status in AML patients who achieved CR1. Time-dependent analysis was applied considering time-to-HCT as a time-dependent covariate and compared HCT versus non-HCT outcomes according to MRD status at CR1. Among 336 patients assessed at CR1, 35.1% were MRD positive (MRDpos) post-induction. MRDpos patients benefitted from HCT with improved OS and relapse-free survival (RFS), while no benefit was observed in MRDneg patients. In adverse-risk patients, HCT improved OS (HR for OS 0.55; p = 0.05). In intermediate-risk patients, HCT benefit was not significant for OS and RFS. Intermediate-risk MRDpos patients were found to have benefit from HCT with improved OS (HR 0.45, p = 0.04), RFS (HR 0.46, p = 0.02), and CIR (HR 0.41, p = 0.02). Our data underscore the benefit of HCT in adverse risk and MRDpos intermediate-risk AML patients.

Letermovir prophylaxis for cytomegalovirus reactivation in allogeneic hematopoietic cell transplant recipients: Single center Canadian data.

BACKGROUND: Cytomegalovirus (CMV) is associated with morbidity and mortality following allogeneic hematopoietic cell transplantation (alloHCT). Letermovir is a novel antiviral agent that prevents CMV reactivation in alloHCT patients, with limited data regarding influence on post-alloHCT outcomes. METHODS: We retrospectively examined 273 alloHCT recipients, 158 in the non-letermovir cohort (NLC), and 115 in the cohort using letermovir prophylaxis (LC). Patients that received letermovir were CMV-seropositive and met criteria for high risk of CMV reactivation. RESULTS: Median start of letermovir was 21 days post-alloHCT, median duration of prophylaxis was 86 days. Letermovir prophylaxis demonstrated a statistically significant reduction in first CMV reactivation (at 200 days post 63.9% in the NLC vs. 35.7% in the LC; p < .001). On univariate analysis at 1 year, overall survival (OS) for NLC was 79.6% and 79.5% for LC (p = .54). Non relapse mortality (NRM) at 1 year for NLC was 12% and 12.3% for LC (p = .69). Cumulative incidence of relapse (CIR) at 1 year was 13.9% for NLC versus 17.1 for the LC (p = .27). On multivariable analysis, there was no significant difference between the two cohorts for OS, NRM, and CIR. CONCLUSIONS: Letermovir prophylaxis started at day +21 post-alloHCT reduced CMV reactivation, with no impact on posttransplant outcomes.

Impact of cytomegalovirus (CMV) seroconversion pre-allogeneic hematopoietic cell transplantation on posttransplant outcomes.

Cytomegalovirus (CMV) reactivation post-allogeneic hematopoietic cell transplantation (post-alloHCT) increases morbidity and mortality. We sought to determine the frequency of CMV seroconversion in patients pre-alloHCT and to investigate the impact on posttransplant outcomes. We retrospectively investigated 752 adult patients who underwent alloHCT at our center from January 2015 to February 2020 before the adoption of letermovir prophylaxis. CMV serology was assessed at consult and pretransplant. The cohort was divided into four groups based on pretransplant CMV seroconversion: negative to positive (Group 1), positive to negative (Group 2), consistently negative (Group 3), and consistently positive (Group 4). Eighty-nine patients (12%) had seroconverted from negative to positive, 17 (2%) from positive to negative, 151 (20%) were consistently seronegative, and 495 (66%) were consistently seropositive pretransplant. For the four CMV serostatus groups, cumulative incidence of CMV reactivation at 6 months posttransplant was 4.5%, 47.1%, 6.6%, and 76.6% for Groups 1, 2, 3, and 4, respectively (p < .0001). No differences between groups were seen regarding Grade III-IV acute graft-versus-host disease (GVHD) (p = .91), moderate/severe chronic GVHD (p = .41), or graft failure (p = .28). On multivariable analysis, there was no impact of CMV serostatus group on overall survival (p = .67), cumulative incidence of relapse (p = .83) or non-relapse mortality. alloHCT patients who demonstrate CMV seroconversion pretransplant from negative to positive have a very low risk of CMV reactivation posttransplant. The observed seroconversion may be due to passive CMV immunity acquired through blood products. Quantitative CMV immunoglobulin G/immunoglobulin M pretransplant may help differentiate between true seroconversion and passively transmitted CMV immunoglobulin.

Chest CT at X-Ray Dose Using a Noise-Mitigating Weighted Projection: The Thoracic Tomogram. Diagnostic Performance for Pneumonia Detection in Hemato-Oncology Patients.

PURPOSE: To compare the diagnostic performance of a thick-slab reconstruction obtained from an ultra-low-dose CT (termed thoracic tomogram) with standard-of-care low-dose CT (SOC-CT) for rapid interpretation and detection of pneumonia in hemato-oncology patients. METHODS: Hemato-oncology patients with a working diagnosis of pneumonia underwent an SOC-CT followed by an ultra-low-dose CT, from which the thoracic tomogram (TT) was reconstructed. Three radiologists evaluated the TT and SOC-CT in the following categories: (I) infectious/inflammatory opacities, (II) small airways infectious/inflammatory changes, (III) atelectasis, (IV) pleural effusions, and (V) interstitial abnormalities. The TT interpretation time and radiation dose were recorded. Sensitivity, specificity, diagnostic accuracy, ROC, and AUC were calculated with the corresponding power analyses. The agreement between TT and SOC-CT was calculated by Correlation Coefficient for Repeated Measures (CCRM), and the Shrout-Fleiss intra-class correlations test was used to calculate interrater agreement. RESULTS: Forty-seven patients (mean age 58.7 ± 14.9 years; 29 male) were prospectively enrolled. Sensitivity, specificity, accuracy, AUC, and Power for categories I/II/III/IV/V were: 94.9/99/97.9/0.971/100, 78/91.2/86.5/0.906/100, 88.6/100/97.2/0.941/100, 100/99.2/99.3/0.995/100, and 47.6/100/92.2/0.746/87.3. CCRM between TT and SOC-CT for the same categories were .97/.81/.92/.96/.62 with an interobserver agreement of .93/.88/.82/.96/.61. Mean interpretation time was 18.6 ± 5.4 seconds. The average effective radiation dose of TT was similar to a frontal and lateral chest X-ray (0.27 ± 0.08 vs 1.46 ± 0.64 mSv for SOC-CT; P < .01). CONCLUSION: Thoracic tomograms provide comparable diagnostic information to SOC-CT for the detection of pneumonia in immunocompromised patients at one-fifth of the radiation dose with high interobserver agreement.

Molecular, cellular and systemic aspects of epithelial ovarian cancer and its tumor microenvironment.

Ovarian cancer encompasses a heterogeneous group of malignancies that involve the ovaries, fallopian tubes and the peritoneal cavity. Despite major advances made within the field of cancer, the majority of patients with ovarian cancer are still being diagnosed at an advanced stage of the disease due to lack of effective screening tools. The overall survival of these patients has, therefore, not substantially improved over the past decades. Most patients undergo debulking surgery and treatment with chemotherapy, but often micrometastases remain and acquire resistance to the therapy, eventually leading to disease recurrence. Here, we summarize the current knowledge in epithelial ovarian cancer development and metastatic progression. For the most common subtypes, we focus further on the properties and functions of the immunosuppressive tumor microenvironment, including the extracellular matrix. Current and future treatment modalities are discussed and finally we provide an overview of the different experimental models used to develop novel therapies.

Clonal hematopoiesis in the donor does not adversely affect long-term outcomes following allogeneic hematopoietic stem cell transplantation: result from a 13-year follow-up.

Donor clonal hematopoiesis may be transferred to the recipient through allogeneic hematopoietic stem cell transplantation (HSCT), but the potential for adverse long-term impact on transplant outcomes remains unknown. A total of 744 samples from 372 recipients who received HSCT and the corresponding donors were included. Bar-coded error-corrected sequencing using a modified molecular inversion probe capture protocol was performed, which targeted 33 genes covering mutations involved in clonal hematopoiesis with indeterminate potential (CHIP) and other acute myeloid leukemia-related mutations. A total of 30 mutations were detected from 25 donors (6.7%): the most frequently mutated gene was TET2 (n=7, 28%), followed by DNMT3A (n=4, 16%), SMC3 (n=3, 12%) and SF3B1 (n=3, 12%). With a median follow-up duration of 13 years among survivors, the presence of CHIP in the donor was not associated with recipient overall survival (P=0.969), relapse incidence (P=0.600) or non-relapse mortality (P=0.570). Donor CHIP did not impair neutrophil (P=0.460) or platelet (P=0.250) engraftment, the rates of acute (P=0.490), or chronic graft-versus-host disease (P=0.220). No significant difference was noted for secondary malignancy following HSCT between the two groups. The present study suggests that the presence of CHIP in allogeneic stem donors does not adversely affect transplant outcomes after HSCT. Accordingly, further study is warranted to reach a clearer conclusion on whether molecular profiling to determine the presence of CHIP mutations is necessary for the pretransplant evaluation of donors prior to stem cell donation.

Influence of conditioning regimen intensity on outcomes post-allogeneic hematopoietic cell transplantation for acute myeloid leukemia in complete morphological remission.

INTRODUCTION: The literature comparing outcomes between myeloablative (MAC) and reduced intensity conditioning (RIC) for acute myeloid leukemia (AML) is conflicting. METHODS: We retrospectively analyzed 451 patients who underwent allogenic hematopoietic cell transplantation (alloHCT) for AML in complete remission (CR) with either RIC (n = 331) or MAC (n = 120) with the use of dual T-cell depletion as graft-versus-host disease (GVHD) prophylaxis. RESULTS: Univariate analysis demonstrated nonrelapse mortality (NRM) at 2 years was 19.1% for MAC and 22.5% for RIC (p = .44). Two-year cumulative incidence of relapse (CIR) was 19.8% for MAC and 24.5% for RIC (p = .15). Two-year overall survival (OS) was 61% and 53% for MAC and RIC, respectively (p = .02). Two-year graft-versus-host disease relapse-free survival (GRFS) was 40.8% for MAC and 33.7% for RIC (p = .30). A propensity score-matched analysis was done matching patients for age, HLA match, in vivo T-cell depletion, and Disease Risk Index (DRI). Two-year OS was 67% for MAC, 66% for RIC (p = .95). A subgroup analysis identified that matched related donor transplants benefit from MAC with OS at 2 years 82.6% versus 57.3% for RIC (p = .006). CONCLUSIONS: In the matched-related donor setting, MAC regimens may offer superior survival. Overall, for our cohort of predominantly in vivo T-cell depleted patients the outcomes of MAC and RIC were similar.

Mutational profile, outcomes, and impact of allogeneic hematopoietic stem cell transplantation in adult patients with acute myeloid leukemia and inconclusive cytogenetic analysis.

BACKGROUND: Inconclusive cytogenetic analysis (IC) at baseline has been reported as a predictor of poor prognosis in patients with acute myeloid leukemia (AML). The mutational profile in this group of patients, and its impact on outcomes have not been reported. METHODS: We retrospectively analyzed adult patients (≥18 years) with newly diagnosed AML treated with intensive induction chemotherapy between 2015 and 2019. Patients with any documented cytogenetic abnormalities were excluded. Targeted next generation sequencing (NGS) was performed in all patients. Baseline characteristics, mutation profile, and outcomes were compared between patients with normal cytogenetics(NC) and those with IC. RESULTS: Sixty-one patients (males 39.3%; median age 59 years) had IC at diagnosis. The proportion of patients with mutations in genes with proven prognostic impact were not different between AML patients with IC and NC. AML patients with NC were more likely to harbor the prognostically favorable NPM1mut /FLT3-ITDwt mutational combination conferring "favorable" risk status. As a result, a larger proportion of patients in the IC group underwent allogeneic hematopoietic stem cell transplantation (allo HCT; 54.1% vs. 39.6%; p = .02). The 2-year RFS (55.9% vs. 58.5%; p = .29) and OS (61.9% vs. 66.9%; p = .48) were similar in IC and NC patients. There was no difference in survival of patients who underwent allo HCT when compared with patients who did not (p = .99). CONCLUSIONS: Inconclusive cytogenetic analysis may not be an independent prognostic indicator in AML. In such patients, molecular abnormalities detected through NGS or whole genome sequencing are more likely to be informative.

Prognostic implication of pre-transplant FEV1 on long-term outcomes following allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Pre-transplant pulmonary function testing (PFT) is essential before allogeneic hematopoietic stem cell transplant (HCT), yet the optimal cutoff value for affecting transplant outcomes remains poorly defined. STUDY DESIGN: Retrospective analysis of pre-HCT PFT data from 605 consecutive patients at the Princess Margaret Cancer Centre between January 1, 2004 and December 31, 2013 used binary recursive partitioning to identify cutoff values for overall survival (OS) as an endpoint of transplant outcomes. These values were compared to HCT comorbidity index (HCT-CI) FEV1 cutoffs for OS, cumulative incidence of relapse and non-relapse mortality. RESULTS: FEV1 ≥ 81% was the identified cutoff point. The OS rate at 3 years showed 49.8% (FEV1 ≥ 81%) vs. 36.6% (<81%, p < .001). For HCT-CI cutoffs, the OS rate at 3 years for FEV1 ≥ 80%, 66%-80% and ≤65% were 49.0%, 38.1% and 37.6% (p = .011), respectively. Multivariate analysis confirmed that FEV1 ≥ 81% predicted reduced mortality (HR 0.682, p = .001). Subgroup analysis showed both FEV1 ≥ 81% and FEV1 by HCT-CI cutoffs may stratify patients according to OS and NRM risk in subgroups receiving myeloablative, but not reduced intensity conditioning. CONCLUSION: FEV1 ≥ 81% can predict OS and NRM in our cohort and is potentially simpler when risk stratifying patients undergoing allogeneic HCT, particularly those receiving myeloablative conditioning.

Multiplex proteomics using proximity extension assay for the identification of protein biomarkers predictive of acute graft-vs.-host disease in allogeneic hematopoietic cell transplantation.

OBJECTIVES: Allogeneic hematopoietic cell transplantation (HCT) is associated with acute graft-vs.-host disease (aGVHD). The presented study applied a novel multiplex antibody-based proximity extension assay (PEA) proteomic platform that can detect thousands of serum proteins simultaneously for the identification of potential biomarkers of aGVHD. METHODS: Serum samples from 28 patients who underwent allogeneic HCT for acute myeloid leukemia (AML) were analyzed; 17 were diagnosed with grade II-IV aGVHD while 11 patients were not. Samples collected on day -6, day 0, +14, +30, +60 and +90 post-HCT were analyzed for the relative concentrations of 552 proteins. The concentration of each protein from baseline to the closest time point before onset of aGVHD, or to the latest time point in control patients, was documented. RESULTS: Individualized analysis identified 26 proteins demonstrating ≥3-fold increase at aGVHD onset compared to baseline, eliminating proteins with a similar increase in controls. Another approach used paired t-testing and logistic regression that identified a four-marker panel, including SLAMF7, IL-1ra, BTN3A2 and DAB2, where individual log-likelihood ratios ranged from 3.99 to 8.15 (logistic regression, p=0.004-0.046). When combined, the four-marker panel demonstrated an area under the curve (AUC) of 0.90 (95% CI: 0.78-1.00; p=0.0006) with high negative predictive value of 81.8% and positive predictive value of 86.7%. All four markers play a physiological role in immune regulation. Among these, three were also present in the individualized analysis (SLAMF7, IL-1ra and BTN3A2). CONCLUSIONS: We conclude that serum proteins identified using multiplex proteomics, particularly SLAMF7, IL-1ra, BTN3A2 and DAB2, may potentially predict aGVHD.

Weight loss post-allogeneic stem cell transplant is associated with increased transplant-related mortality.

PURPOSE: Allogeneic stem cell transplant (allo-HSCT) patients are at risk of malnutrition and weight loss from impaired oral intake resulting from gastrointestinal toxicities, dysgeusia, and psychological effects. METHODS: A retrospective review of 264 adult patients transplanted at Princess Margaret Cancer Centre who achieved relapse-free survival up to 3 months after allo-HSCT was performed. RESULTS: Overall incidence of patients who experienced WL (WL) ≥ 10% from HSCT to 3-month post-transplant was 45.9% and from HSCT to 6 months was 56.6%. Patients with ≥ 10% WL from allo-HSCT at 3 months and 6 months had similar 2-year overall survival (OS) compared to those with < 10% WL, 55.7% vs 62.8% (HR = 1.38, p = 0.11) and 71.1% vs 77.2% (HR = 1.37, p = 0.27), respectively. Patients with ≥ 10% WL 3 and 6 months from allo-HSCT also had similar 2-year relapse-free survival (RFS) compared to those with < 10% WL, 48.1% vs 55.8% (HR = 1.26, p = 0.22), and 62.7% vs 69.8% (HR = 1.29, p = 0.31), respectively. The 2-year transplant-related mortality (TRM) was higher for those with ≥ 10% WL from allo-HSCT to 3 months, 35.4% vs 16.9% (HR = 2.39, p = 0.0007) and 6 months, 22% vs 8% (HR = 3.1, p = 0.0034). Although statistical significance was not observed for OS or RFS, patients who experienced ≥ 10% WL 3- and 6-months post allo-HSCT experienced higher 2-year TRM. These results highlight the importance of early intervention and close monitoring of weight post allo-HSCT. CONCLUSION: Approaches to WL post allo-HSCT should be multifaceted and include members of the interdisciplinary team in order to decrease TRM.

Real-world clinical characterization, healthcare resource utilization and productivity loss in chronic graft versus host patients exposed to extracorporeal photopheresis in Sweden.

BACKGROUND: Extracorporeal photopheresis (ECP) is frequently used to treat moderate-severe chronic graft versus host disease (cGVHD), however limited data exists describing ECP treatment effects on healthcare and societal costs. We aimed to characterize clinical and health economic outcomes and productivity loss in cGVHD patients exposed to ECP. METHODS: We identified 2708 patients aged ≥ 18 years with a record of allogeneic hematopoietic stem cell transplantation (HSCT) in the Swedish Patient Register between 2006 and 2020. Patients exposed to ECP from 3-months post HSCT (index) were included (n= 183). Data was linked to the Prescribed Drug Register, the Cause of Death Register, and the Longitudinal Integrated Database for Health Insurance and Labor Market Studies (LISA). RESULTS: The median patient age at index was 51 years (IQR1-3; 38-61). In the 3-month period before ECP initiation compared to 9-12 months post-ECP, the cumulative three-month dose per patient decreased prednisolone/prednisone (1,381 mg vs. 658 mg, p < 0.001) and cyclosporin (12,242 mg vs. 3,501 mg, p < 0.001). Infection incidence also decreased over the same period (79.2% vs 59.1%, p < 0.001). Time spent in healthcare decreased from 68.9% to 22.1% from the first and fifth follow-up year respectively, and corresponding annual healthcare cost reduced from €27,719 to €1,981. Among patients < 66 years of age, sickness-related workplace absence decreased from 73.2% to 31.9% between the first and fifth follow-up year, with median annual productivity loss decreasing from €20,358 to €7,211 per patient. CONCLUSIONS: ECP was associated with reduced use of corticosteroids, immunosuppressive agents, and fewer infections. Furthermore, cost and healthcare utilization decreased over time.

Allogeneic stem cell transplantation in adults 2015-21. / Allogen stamcelletransplantasjon hos voksne 2015­21.

BACKGROUND: Allogeneic stem cell transplantation is the only curative treatment for several malignant and non-malignant haematological diseases, and is associated with a risk of serious complications. In recent years, several changes have been introduced with the aim of reducing treatment-related complications. This retrospective study reviews quality indicators for patients who underwent transplantation in the period 2015-21. MATERIAL AND METHOD: The study included 589 adult patients who were treated with allogeneic stem cell transplantation for the first time at Oslo University Hospital in the period May 2015 to May 2021. Three two-year periods are compared using descriptive methods. RESULTS: In the period 2015-2021, the number of first-time transplant patients per year increased from 85 to 113. One-year survival increased from 68 % in the first two-year period to 74 % in the second period and 82 % in the last period. Both acute and chronic GVHD were reduced, and one-year GVHD-free and relapse-free survival increased from 42 % to 60 % during the study period. INTERPRETATION: Since 2015, the number of transplants has increased, while survival has improved and the risk of complications is lower.

A novel CD34-specific T-cell engager efficiently depletes acute myeloid leukemia and leukemic stem cells in vitro and in vivo.

Less than a third of patients with acute myeloid leukemia (AML) are cured by chemotherapy and/or hematopoietic stem cell transplantation, highlighting the need to develop more efficient drugs. The low efficacy of standard treatments is associated with inadequate depletion of CD34+ blasts and leukemic stem cells, the latter a drug-resistant subpopulation of leukemia cells characterized by the CD34+CD38- phenotype. To target these drug-resistant primitive leukemic cells better, we have designed a CD34/CD3 bi-specific T-cell engager (BTE) and characterized its anti-leukemia potential in vitro, ex vivo and in vivo. Our results show that this CD34-specific BTE induces CD34-dependent T-cell activation and subsequent leukemia cell killing in a dose-dependent manner, further corroborated by enhanced T-cell-mediated killing at the singlecell level. Additionally, the BTE triggered efficient T-cell-mediated depletion of CD34+ hematopoietic stem cells from peripheral blood stem cell grafts and CD34+ blasts from AML patients. Using a humanized AML xenograft model, we confirmed that the CD34-specific BTE had in vivo efficacy by depleting CD34+ blasts and leukemic stem cells without side effects. Taken together, these data demonstrate that the CD34-specific BTE has robust antitumor effects, supporting development of a novel treatment modality with the aim of improving outcomes of patients with AML and myelodysplastic syndromes.

Patient age and donor HLA matching can stratify allogeneic hematopoietic cell transplantation patients into prognostic groups.

BACKGROUND: Mixed results surround the accuracy of commonly used prognostic risk scores to predict overall survival (OS) and non-relapse mortality (NRM) in allogeneic hematopoietic stem cell transplant (allo-HCT) recipients. We hypothesize that a simple prognostic score performs better than conventional scoring systems. PATIENTS AND METHODS: OS risk factors, HCT-CI, age-HCT-CI, and augmented-HCT-CI were studied in 299 patients who underwent allo-HCT for myeloid and lymphoid malignancies. A scoring system was developed based on results and validated in a different cohort of 455 patients. RESULTS: Two-year OS was 51% (95% confidence interval (CI) 0.45-0.56); 2-year NRM was 34% (95% CI 0.29-0.39). HCT-CI and associated scores were grouped into 0-2 and ≥3. Age and HLA mismatch status were the only risk factors to affect OS in multivariate analysis (p = 0.02 and 0.05, respectively). HCT-CI and associated scores were not informative for OS prediction. The weighted scoring system assigned 0 to 2 points for age < 50, 50-64, or ≥65, respectively, and 0-1 points for no HLA mismatch versus any mismatch (except HLA-DQ). Distinct 2-year OS (62%, 53%, and 38% [p = <0.001]) and NRM (24%, 34%, and 43% [p = 0.02]) groups were characterized. The scoring system was validated in a second independent cohort with similar results on OS and NRM (p < 0.001). CONCLUSIONS: A simple scoring system based on recipient's age and mismatch status accurately predict OS and NRM in two distinct cohorts of allo-HCT patients. Its simplicity makes it a helpful tool to aid clinicians and patients in clinical decision-making.

Allogeneic hematopoietic stem cell transplantation in patients with therapy-related hematologic malignancies developing after multiple myeloma.

INTRODUCTION: Increasing survival of patients with multiple myeloma (MM) has resulted in an increased recognition of therapy-related hematological malignancies (t-MDS/AML, t-ALL, and t-CMML). There are limited data on the role of allogeneic hematopoietic stem cell transplantation (HCT) in this patient population. PATIENTS AND METHODS: We retrospectively reviewed patients who underwent HCT for t-MDS/AML, t-ALL, and t-CMML developing after receiving treatment for MM at our center. Patients were analyzed for myeloma characteristics and therapy, time to diagnosis of therapy-related hematological neoplasms, clinical, laboratory characteristics, transplant details, relapse-free survival (RFS), and overall survival (OS). RESULTS: Twenty patients underwent HCT for therapy-related hematological malignancies after MM (t-MDS/AML = 13, t-ALL = 6, t-CMML = 1). Median(range) age at time of transplant was 62.5 (49-73) years and 70% (n = 14) were male. The most common cytogenetic abnormality was complex/monosomal karyotype in 30% (n = 6) followed by monosomy/deletion of chromosome 5 or 7 in 15% (n = 3) of patients each. Donors were human leukocyte antigen matched (10/10 or 6/6) siblings in 30% (n = 6), unrelated in 60% (n = 12) and haploidentical in 10% (n = 2) patients. Estimated 2-year OS and RFS for the whole cohort were 53.1% and 47.2% respectively. There was a trend toward better survival in patients with t-ALL when compared to t-MDS/AML; however, the difference was not statistically significant. We did not find any pre-transplant or post-transplant factors that were predictive of survival outcomes after multivariate analysis. CONCLUSIONS: Allogeneic HCT provides substantial long-term disease-free survival in a proportion of patients with MM-associated therapy-related hematological malignancies. Multicenter studies with more patients and longer follow-up may provide additional information about factors affecting outcomes.

Anti-thymocyte globulin and post-transplant cyclophosphamide predisposes to inferior outcome when using cryopreserved stem cell grafts.

During 2020, the concurrent novel COVID-19 pandemic lead to widespread cryopreservation of allogeneic hematopoietic cell transplant grafts based on National Marrow Donor Program and European Society of Blood and Marrow Transplantation recommendations, in order to secure grafts before the start of conditioning chemotherapy. We sought to examine the impact of this change in practice on patient outcomes. We analyzed the outcomes of 483 patients who received hematopoietic stem cell transplantation (HSCT) between August 2017 and August 2020, at Princess Margaret Cancer Centre, Canada, in the retrospective study, comparing the outcomes between those who received cryopreserved or fresh peripheral blood stem cell grafts. Overall compared with those who received fresh grafts (n = 348), patients who received cryopreserved grafts (n = 135) had reduced survival and GRFS, reduced incidence of chronic graft-versus-host disease (GvHD), delay in neutrophil engraftment, and higher graft failure (GF), with no significant difference in relapse incidence or acute GvHD. However, recipients of cryopreserved matched-related donor HSCT showed significantly worse OS, NRM, GRFS compared with fresh grafts. Multivariable analysis of the entire cohort showed significant impact of cryopreservation on OS, relapse, cGvHD, GF, and GRFS. We conclude that cryopreservation was associated with inferior outcomes post-HSCT, possibly due to the combination of ATG and post-transplant cyclophosphamide impacting differential tolerance to cryopreservation on components of the stem cell graft; further studies are warranted to elucidate mechanisms for this observation.

Anti-thymocyte Globulin and Post-Transplant Cyclophosphamide do not abrogate the inferior outcome risk conferred by human leukocyte antigen-A and -B mismatched donors.

In donor selection for allogeneic stem cell transplant, several factors are considered for potential impact on transplant outcome. Previous publications suggested single HLA-mismatched unrelated donors (MMUD) may be equivalent to 10/10 matched unrelated donors (MUDs). We retrospectively examined factors affecting outcome in a single-center study using ATG followed by post-transplant cyclophosphamide, termed ATG-PTCy, GvHD prophylaxis. Fifty-two patients who received grafts from MMUD and 188 patients transplanted from MUD between January 2015 and December 2019, at Princess Margaret Cancer Centre, Canada, were enrolled. All patients received reduced-intensity conditioning. Overall survival for 9/10 recipients at 2 years was significantly worse, 37.2% versus 68.5% for 10/10 MUDs, p < .001, as were NRM at 1 year 39.5% versus 11.7%, p < .001, and GRFS at 2 years 29.8% versus 58.8%, p < .001, respectively, potentially due to higher incidence of infections including CMV. By multivariable analysis, factors correlating with survival negatively were DRI, and MMUD, whereas for NRM MMUD and increasing age were unfavorable. For GRFS significant unfavorable factors included donor age ≤32 years, female donor to male recipient, DRI high-very high and MMUD. These data suggest that MMUD, primarily HLA-A and HLA-B MMUD, confer significantly inferior outcome despite use of ATG-PTCy. Further development of novel conditioning regimens and GvHD prophylaxis is needed to mitigate these risks.