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We systematically evaluated the primary and secondary endpoints used in acute myeloid leukemia (AML) phase III randomized controlled trials (RCTs). We included 238 phase III AML RCTs in the past 15 years that reported 279 primary endpoints and 657 secondary endpoints. Overall survival (OS), progression-free survival (PFS), event-free survival (EFS), and complete remission (CR) were primary endpoints in 120 (43%), 34 (12%), 30 (11%), and 41 (15%) studies, respectively. OS (12.5%), PFS (13.2%), CR (14%), safety (11%), and EFS (9%) were commonly reported secondary endpoints. Among primary endpoints, a higher use of OS (OR 2.03, 95%CI 1.10-3.75

The utilization of hematopoietic stem cell transplantation (HSCT) has been rapidly growing due to multiple factors, including better availability of donors and improved supportive care. Hyperbaric oxygen has been associated with the improvement of hematopoietic stem cell (HSC) homing at the time of transplant through lowering erythropoietin levels in preclinical studies. We studied the role of hyperbaric oxygen (HBO) in the enhancement of engraftment of HSC when utilized prior to umbilical cord HSCT and autologous HSCT in two pilot clinical trials with excellent safety profiles. In these two pilot studies, we observed an uncommon phenomenon post-transplant, particularly a significant peripheral blood lymphocytosis and lymphocyte infiltration of different tissues in 3/34 of HBO-treated patients. This peripheral blood lymphocyte expansion was associated with various clinical manifestations that can be confused with infections, inflammatory conditions, or disease relapse. We hypothesize that this observation is related to different immune reconstitution dynamics related to the use of HBO. While the incidence is ~9%, this may have implications as HBO is being investigated in larger clinical trials. This case series highlights the clinical presentation, course, outcome, and potential implications of this significant rise in lymphocytes when utilizing HBO before HSCT.

We conducted a systematic review and meta-analysis to evaluate outcomes after allogeneic hematopoietic stem cell transplantation (HSCT) in TP53-mutated acute myeloid leukemia (AML). We performed a literature search on PubMed, Embase, Cochrane Library, and ClinicalTrials.gov. After screening 592 manuscripts, eight studies were included. Data were extracted following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Pooled analysis was done using the meta-package by Schwarzer et al. Proportions with 95% confidence intervals (CIs) were computed. We analyzed 297 patients. The median follow-up was 45 (0.9-407.3) months. The pooled 2-year overall survival was 29.7% (95% CI 0.17-0.43

BACKGROUND: Because of their well-described immunosuppressive properties, allogeneic adult human mesenchymal stromal cells (MSC) derived from bone marrow have demonstrated safety and efficacy in steroid refractory acute graft versus host disease (SR aGVHD). Clinical trials have resulted in variable success and an optimal source of MSC has yet to be defined. Based on the importance of maternal-fetal interface immune tolerance, extraembryonic fetal tissues, such as the umbilical cord, may provide an superior tissue source of MSC to mediate immunomodulation in aGVHD. METHODS: A two-dose cohort trial allogeneic Wharton’s Jelly-derived mesenchymal stromal cells (WJMSC, referred to as MSCTC-0010, here) were tested in 10 patients with de novo high risk (HR) or SR aGVHD post allogeneic hematopoietic stem cell transplantation (allo-HCT). Following Good Manufacturing Practices isolation, expansion and cryostorage, WJMSC were thawed and administered via intravenous infusions on days 0 and 7 at one of two doses (low dose cohort, 2×10(6)/kg, n=5; high dose cohort, 10×10(6)/kg, n=5). To evaluate safety, patients were monitored for infusion related toxicity, Treatment Related Adverse Events (TRAE) til day 42, or ectopic tissue formation at day 90. Clinical responses were monitored at time points up to 180 days post infusion. Serum biomarkers ST2 and REG3α were acquired 1 day prior to first MSCTC-0010 infusion and on day 14. RESULTS: Safety was indicated, e.g., no infusion-related toxicity, no development of TRAE, nor ectopic tissue formation in either low or high dose cohort was observed. Clinical response was suggested at day 28: the overall response rate (ORR) was 70%, 4 of 10 patients had a complete response (CR) and 3 had a partial response (PR). By study day 90, the addition of escalated immunosuppressive therapy was necessary in 2 of 9 surviving patients. Day 100 and 180 post infusion survival was 90% and 60%, respectively. Serum biomarker REG3α decreased, particularly in the high dose cohort, and with REG3α decrease correlated with clinical response. CONCLUSIONS: Treatment of patients with de novo HR or SR aGVHD with low or high dose MSCTC-0010 was safe: the infusion was well-tolerated, and no TRAEs or ectopic tissue formation was observed. A clinical improvement was seen in about 70% patients, with 4 of 10 showing a complete response that may have been attributable to MSCTC-0010 infusions. These observations indicate safety of two different doses of MSCTC-0010, and suggest that the 10 × 10(6) cells/kg dose be tested in an expanded randomized, controlled Phase 2 trial.

INTRODUCTION: Next-generation sequencing (NGS) analysis showed clonal cytopenia of undetermined significance (CCUS) as an immediate precursor to myelodysplastic syndrome (MDS). METHODS: We evaluated and compared morphologic, multiparametric flow cytometry (MFC), and molecular genetic findings in patients with CCUS (n = 37), MDS (n = 75), and acute myeloid leukemia with myelodysplasia-related changes (AML-MRC, n = 24). RESULTS: CCUS patients showed variable MFC abnormalities including >2% CD34+ myeloblasts (5.8%), altered antigen expression on myeloblasts, monocytes, and granulocytes (1.2, 1.5, and 0.2/case), abnormal maturation of myeloblasts (45.8%), decreased hematogones (17.6%), and decreased side scatter (SSC) of granulocytes (11.4%). CCUS patients with high-risk mutations showed significantly more MFC abnormalities. However, CCUS patients with >20% variant allelic fraction (VAF) did not show more MFC aberrations than the rest of the group. MDS patients showed significantly more MFC abnormalities compared with CCUS patients (p = 7.8E-05 – 0.047). Low-grade MDS patients showed significantly fewer MFC abnormalities compared with high-grade MDS or AML-MRC patients (p = 1.89E-05– 0.04). AML-MRC patients showed significantly elevated blast counts, more antigen aberrations, decreased hematogones, and decreased SSC of granulocytes compared with CCUS patients (p = 2.0E-05– 0.01). CCUS patients carried predominantly TET2/DNMT3A/ASXL1 mutations. They harbored fewer mutations in gene coding splicing factors compared with MDS patients (p = .0001–. 02) and fewer mutations in tumor suppressor and transcription factor genes compared with AML-MRC patients (p = .0006– .02). CONCLUSIONS: CCUS is an immediate precursor to low-g rade MDS. The progression from CCUS to MDS to AML-MRC is a stepwise process that requires acquisition of mutations in splicing, transcription factor, and tumor suppressor genes with accumulations of additional MFC abnormalities.

Both mesenchymal stem cells (MSCs) and their corresponding small extracellular vesicles (sEVs, commonly referred to as exosomes) share similar immunomodulatory properties that are potentially beneficial for the treatment of acute graft versus host disease (aGvHD). We report that clinical grade Wharton's Jelly‐derived MSCs (WJMSCs) secrete sEVs enriched in programmed death‐ligand 1 (PD‐L1), an essential ligand for an inhibitory immune checkpoint. A rapid increase in circulating sEV‐associated PD‐L1 was observed in patients with aGvHD and was directly associated with the infusion time of clinical grade WJMSCs. In addition, in vitro inhibitory antibody mediated blocking of sEV‐associated PD‐L1 restored T cell activation (TCA), suggesting a functional inhibitory role of sEVs‐PD‐L1. PD‐L1‐deficient sEVs isolated from WJMSCs following CRISPR‐Cas9 gene editing fail to inhibit TCA. Furthermore, we found that PD‐L1 is essential for WJMSC‐derived sEVs to modulate T cell receptors (TCRs). Our study reveals an important mechanism by which therapeutic WJMSCs modulate TCR‐mediated TCA through sEVs or sEV‐carried immune checkpoints. In addition, our clinical data suggest that sEV‐associated PD‐L1 may be not only useful in predicting the outcomes from WJMSC clinical administration, but also in developing cell‐independent therapy for aGvHD patients.

Melanoma treatment has been revolutionized over the past decade. Long-term results with immuno-oncology (I-O) agents and targeted therapies are providing evidence of durable survival for a substantial number of patients. These results have prompted consideration of how best to define long-term benefit and cure. Now more than ever, oncologists should be aware of the long-term outcomes demonstrated with these newer agents and their relevance to treatment decision-making. As the first tumor type for which I-O agents were approved, melanoma has served as a model for other diseases. Accordingly, discussions regarding the value and impact of long-term survival data in patients with melanoma may be relevant in the future to other tumor types. Current findings indicate that, depending on the treatment, over 50% of patients with melanoma may gain durable survival benefit. The best survival outcomes are generally observed in patients with favorable prognostic factors, particularly normal baseline lactate dehydrogenase and/or a low volume of disease. Survival curves from melanoma clinical studies show a plateau at 3 to 4 years, suggesting that patients who are alive at the 3-year landmark (especially in cases in which treatment had been stopped) will likely experience prolonged cancer remission. Quality-of-life and mixture-cure modeling data, as well as metrics such as treatment-free survival, are helping to define the value of this long-term survival. In this review, we describe the current treatment landscape for melanoma and discuss the long-term survival data with immunotherapies and targeted therapies, discussing how to best evaluate the value of long-term survival. We propose that some patients might be considered functionally cured if they have responded to treatment and remained treatment-free for at least 2 years without disease progression. Finally, we consider that, while there have been major advances in the treatment of melanoma in the past decade, there remains a need to improve outcomes for the patients with melanoma who do not experience durable survival.

BackgroundTumor-infiltrating lymphocyte (TIL) therapy is a personalized cancer treatment which involves generating ex vivo cultures of tumor-reactive T cells from surgically resected tumors and administering the expanded TILs as a therapeutic infusion. Phase 1 of many TIL production protocols use aldesleukin (IL-2) alone to establish TIL cultures (termed “PreREP” (Pre-Rapid Expansion Protocol)); however, this fails to consistently produce TIL cultures from renal cell carcinoma (RCC) in a timely manner. Adding mitogenic stimulation via anti-CD3/anti-CD28 beads along with IL-2 to the fresh tumor digest (FTD) during TIL generation (termed “FTD+ beads”) increases successful TIL culture rates; however, T cells produced by this method may be suboptimal for adoptive transfer. We hypothesize that adherent cell depletion (ACD) before TIL expansion will produce a superior TIL product by removing the immunosuppressive signals originating from adherent tumor and stromal cells. Here we investigate if “panning,” a technique for ACD prior to TIL expansion, will impact the phenotype, functionality and/or clonality of ex vivo expanded RCC TILs.MethodsTumor specimens from 55 patients who underwent radical or partial nephrectomy at the University of Kansas Medical Center (KUMC) were used to develop the panning method and an additional 19 specimens were used to validate the protocol. Next-generation sequencing, immunohistochemistry/immunocytochemistry and flow cytometry were used during method development. The phenotype, functionality and clonality of autologous TILs generated in parallel by panning, PreREP, and FTD+ beads were assessed by flow cytometry, in vitro co-culture assays, and TCRB CDR3 sequencing.ResultsTIL cultures were successfully generated using the panning protocol from 15/16 clear cell, 0/1 chromophobe, and 0/2 papillary RCC samples. Significantly fewer regulatory (CD4+/CD25+/FOXP3+) (p=0.049, p=0.005), tissue-resident memory (CD8+/CD103+) (p=0.027, p=0.009), PD-1+/TIM-3+ double-positive (p=0.009, p=0.011) and TIGIT+ T cells (p=0.049, p=0.026) are generated by panning relative to PreREP and FTD+ beads respectively. Critically, a subset of TILs generated by panning were able to degranulate and/or produce interferon gamma in response to autologous tumor cells and the average tumor-reactive TIL yield was greatest when using the panning protocol.ConclusionsRemoving immunosuppressive adherent cells within an RCC digest prior to TIL expansion allow for the rapid production of tumor-reactive T cells with optimal characteristics for adoptive transfer.

Umbilical cord blood (UCB) transplantation is a promising option for hematopoietic stem cell transplantation in patients with hematologic malignancies who lack an HLA-matched sibling or well-matched unrelated donor; however, it has a higher incidence of delayed or failed engraftment because cell doses are low and bone marrow homing is inefficient. We have demonstrated that pre-treating irradiated immune-deficient mice with hyperbaric oxygen (HBO) prior to UCB CD34+ cell transplantation lowered host systemic erythropoietin (EPO) and improved UCB CD34+ cell homing and engraftment. These findings suggested that EPO-EPO-R signaling plays a role in UCB CD34+ homing and engraftment. In a pilot clinical trial, we showed that recipients of HBO therapy prior to UCB cell infusion had reduced systemic EPO, which was associated with improved kinetics of blood count recovery. Although early clinical outcomes at day 100 were encouraging, with improved overall survival, the long-term effects of HBO therapy on UCB-transplanted patients were not evaluated. In this study, we examined the long-term outcome of patients in our pilot study, compared with a historic control group, and correlated their clinical outcomes to serum EPO response to HBO. While 50% of HBO-treated patients received single UCB units, ~ 90% of the control patients received double UCB units. Although HBO patients had much better rates of survival at 6 months, their 1-year survival did not significantly differ from the control group. HBO-treated patients had on average lower relapse and non-relapse mortality rates, and less chronic graft versus host disease (GVHD), but had increased acute GVHD. However, these differences were not statistically significant, probably because of the small sample size. In the HBO-treated cohort, immune reconstitution analysis showed significant improvement in early B cell recovery, with a trend toward improvement in early NK cell recovery. When we evaluated the ratio of 8 h to baseline EPO levels, we found a non-significant trend toward lower EPO values in those who neither relapsed nor died by 1 year, compared to those who died or relapsed. This result suggests that EPO response to HBO may be associated with better outcomes. Disease progression-free survival was also improved in those who had more than 80% reduction in EPO levels in response to HBO. Our study highlights the long-term safety of HBO therapy when used prior to UCB transplantation. Future UCB transplant patients who receive HBO should have their serum EPO response measured, as it may be a marker of relapse/mortality.

Background: Patients with TP53 MUT MDS/AML experience poor clinical outcomes with high rates of disease recurrence and short overall survival (OS). Characterization of these individuals' post-HCT mortality is uniquely challenging due to competing risks from disease relapse and treatment toxicity. Transplant registries contain high-level outcomes data, however, there is a lack of detailed data in molecularly defined subsets of diease. This analysis was undertaken to bridge this gap. Methods: Allogeneic HCT recipients between 1/2014 and 12/2018 were retrospectively studied. Key inclusion criteria were TP53 MUT by NGS or deletion of chromosome 17/17p by FISH/cytogenetics. The primary outcome of non-relapse mortality (NRM) was defined as death from any cause other than disease with relapse as competing risk. Secondary outcomes for this analysis were OS, cumulative incidence of relapse (CIR), and relapse free survival (RFS). Relapse was defined as relapse/progression with NRM as competing risk. Results: 384 TP53 MUT MDS/AML patients were analyzed. 55% of patients were transplanted for AML, 41% received myeloablative conditioning (MAC), 39% had secondary MDS/AML, and 26% received prior chemo and/or radiation therapy (XRT). Median time from HCT to last follow-up was 321 days (range 8-2,385 days). Mutational data was available in 264 patients and cytogenetic data was available in 368 patients; 78% of patients had a complex karyotype (CK), 82% had TP53 missense mutations, and 74% had bi-allelic targeting of the TP53 gene. The incidence of all-grade acute and chronic GVHD (cGVHD) was 52% and 31%, respectively. One and 2 year OS was 48.5% and 30.9%, respectively. Estimated CIR at 1 and 2 years was 49% and 54.9%, respectively. The 1 year NRM was 13.7% and 2 year NRM was 18.1%. In multivariate analysis (MVA), there was no association between NRM and the clinical, molecular, or genetic features of TP53 MUT MDS/AML. HCT diagnosis of MDS (HR: 0.67, 95% CI: 0.46-0.97, p: 0.036), mono-allelic TP53 MUT (HR: 0.6, 95% CI: 0.39-0.94, p: 0.023), achievement of full donor PB chimerism (HR: 0.33, 95% CI: 0.14-0.85, p: 0.022), BM chimerism (HR: 0.33, 95% CI: 0.18-0.60, p: 0.003), and cGVHD (HR: 0.35, 95% CI: 0.23-0.51, p: In subgroup analysis, history of chemo and/or XRT increased NRM in AML (HR: 4.24, 95% CI: 1.35-13.39, p: 0.014). Pre-HCT TP53 MUT persistence by NGS (HR: 3.59, 95% CI: 1.43-9, p: 0.007) predicted for post-HCT relapse whereas pre-HCT CR (HR: 2.93, 95% CI: 1.54-5.59, p: 0.001) and full donor BM chimerism (HR: 0.14, 95% CI: 0.05-0.38, p: No significant NRM associations were identified in MDS. CK (HR: 5.04, 95% CI: 1.95-13.01, p: Conclusions: From this large multi-institutional cohort of TP53 MUT myeloid neoplasms, we report a low NRM rate, likely due to high rates of post-HCT relapse/progression. These data demonstrate associations between bi-allelic TP53m/CK and post-HCT outcomes. Our work highlights the importance donor chimerism after HCT and provides new understanding of the importance of chronic GVHD in TP53 MUT MDS/AML. Figure 1 Figure 1. Disclosures Byrne: Karyopharm: Research Funding. Logan: Amgen, Pfizer, AbbVie: Consultancy; Pharmacyclics, Astellas, Jazz, Kite, Kadmon, Autolus, Amphivena: Research Funding. Lee: CareDx: Membership on an entity's Board of Directors or advisory committees; Kadmon: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Fresensius Kabi: Consultancy; Jazz,: Consultancy; Incyte: Research Funding. Goodman: Seattle Genetics: Consultancy, Speakers Bureau; EUSA Pharma: Consultancy, Honoraria. Gill: Interius Biotherapeutics: Current holder of stock options in a privately-held company, Research Funding; Novartis: Other: licensed intellectual property, Research Funding; Carisma Therapeutics: Current holder of stock options in a privately-held company, Research Funding. Jimenez: Takeda: Research Funding; AbbVie: Research Funding. Metheny: Pharmacosmos: Honoraria; Incyte: Speakers Bureau. Bhatnagar: Pfizer: Honoraria; Celgene: Honoraria; Novartis: Honoraria; Astellas: Honoraria; Cell Therapeutics: Honoraria, Research Funding; Kite: Honoraria; Karyopharm: Honoraria, Research Funding; Sumitomo Dainippon Pharma: Research Funding. Hamilton: Syndax: Membership on an entity's Board of Directors or advisory committees; Equilium: Membership on an entity's Board of Directors or advisory committees. Mishra: Novartis: Research Funding. Savona: BMS-Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; CTI: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Geron: Consultancy, Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Ryvu: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sierra Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Taiho: Consultancy, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; ALX Oncology: Research Funding; Astex: Research Funding; Incyte: Research Funding.

Background: Chimeric antigen receptor T cell (CAR-T) therapy is an adoptive T cell immunotherapy that employs the genetically modified T cell to attack the cancer cell. It is widely studied across various hematological and solid organ malignancies. Several autologous CD19 CAR-T cell therapy constructs are now approved for various B cell lymphomas, including aggressive B cell lymphomas, indolent follicular lymphoma and mantle cell lymphoma, and acute lymphoblastic leukemia (ALL). Autologous CD19 CAR-T cell therapy has unprecedented success in relapsed and refractory disease. Long time to manufacture (2-5 weeks) and manufacture failure are challenges associated with risk of interim death and deterioration of CAR-T candidates with rapidly progressive disease. T cell fitness of the autologous product in heavily pretreated patients is also potentially compromised. To overcome these shortcomings, universal "off the shelf" allogeneic CAR-T cell therapy constructs are being developed and studied. Donor sources include healthy donors and cord or induced pluripotent stem cells (iPSCs). These CAR-T constructs have additional gene modifications to mitigate the risk of rejection and graft versus host disease (GVHD). We performed a systematic review and meta-analysis to assess the safety and efficacy of allogeneic CD19 CAR-T cell therapy. Methods: Four databases (Web of Science/MEDLINE/PubMed, Embase, and Cochrane Registry of Controlled Trials) were searched for this systematic review and meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines using MeSH terms and keywords for "Receptors, Chimeric antigen" OR "Artificial-T-cell receptor" OR "immunotherapy, adoptive" OR "CD-19". Our search produced 3506 articles and after removing duplicates, 2243 records were screened. After excluding reviews and irrelevant articles, we included 8 prospective trials of allogeneic CD-19 CAR-T cell therapy enrolling two or more than two patients from Jan 2013 to Nov 2020. We also searched ASH 2020 abstracts to include any additional trials. The methodological quality of the included studies was evaluated using NIH quality assessment tool. Inter-study variance was calculated using the Der Simonian-Laird Estimator. Proportions along with 95% confidence Interval (CI) were extracted to compute pooled analysis using the 'meta' package by Schwarzer et al. in the R programming language (version 4.16-2). Results: A total of 68 patients from 8 studies were evaluated. Median age was 22.5 (4.8-64) years. (Table 1) The median follow-up time was 10 (2-18) months with median number of prior therapies of 3.2 (2-11) as reported by 5 studies. Underlying diagnosis was acute lymphocytic lymphoma (n=49, 72%), chronic lymphocytic leukemia (n=6, 9%), and non-Hodgkin lymphoma (n=13, 19%). The pooled overall response rate (ORR) was 77% (95% CI 0.63-0.89, I 2 =22%, n=68) with a complete response (CR) of 75% (95% CI 0.57-0.90, I 2 =48%, n=65). The pooled incidence of cytokine release syndrome grade I/II and grade III/IV was 53% (95% CI 0.16-0.89, I 2 =89%, n=65) and 10% (95% CI 0.01-0.25, I 2 =50%, n=65) respectively. Neurotoxicity grade I/II was 12% (95%CI 0.01-0.30, I 2 =47%, p=0.09, n=47) and GVHD grade I/II was 8% (95%CI 0.01-0.19, I 2 =0%, p=0.57 n=53). None of the clinical trials reported the duration of response. Conclusion: "Off the shelf" universal CAR-T therapy is early in development. Our available data suggest that allogeneic CD19 CAR-T constructs offer high ORR and CR rates with acceptable safety profiles. GVHD was mainly low grade (grade I-II). Given these findings, allogeneic CAR-T cell therapy is an attractive option to improve timely access compared to available autologous therapy. Extensive preclinical research to develop novel constructs and several phase I/II clinical trials are ongoing to shape the future of "off the shelf" CAR-T cell therapy. Figure 1 Figure 1. Disclosures Hoffmann: Pharmcyclics: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; celgene: Consultancy, Honoraria. Abhyankar: Incyte/Therakos: Consultancy, Research Funding, Speakers Bureau. McGuirk: Fresenius Biotech: Research Funding; Gamida Cell: Research Funding; Pluristem Therapeutics: Research Funding; EcoR1 Capital: Consultancy; Novartis: Research Funding; Astelllas Pharma: Research Funding; Kite/ Gilead: Consultancy, Honoraria, Other: travel accommodations, expense, Kite a Gilead company, Research Funding, Speakers Bureau; Juno Therapeutics: Consultancy, Honoraria, Research Funding; Magenta Therapeutics: Consultancy, Honoraria, Research Funding; Novartis: Research Funding; Bellicum Pharmaceuticals: Research Funding; Allovir: Consultancy, Honoraria, Research Funding.

Coronavirus disease 2019 (COVID-19), a respiratory illness caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was declared a pandemic in March 2020, and has caused more than 600,000 deaths in the United States at the time of this report. Hematopoietic stem cell transplantation (HCT) or chimeric antigen receptor T cell (CAR-T) therapy recipients have a higher risk of mortality with COVID-19 owing to profound immune dysregulation. In this study, we investigated the impact of SARS-CoV-2 in HCT/CAR-T therapy recipients. This single-center prospective study included all (n = 58) adult HCT/CAR-T recipients who were diagnosed with COVID-19 at the University of Kansas Medical Center between March 2020 and May 2021. Baseline and disease-related characteristics were ascertained from medical records. Data were analyzed using SPSS version 21 (IBM, Armonk, NY). Bivariate analyses, using the chi-square and t-test, and logistic regression analyses were conducted. The study included 58 HCT/CAR-T patients who acquired SARS-CoV-2 infection, including recipients of allogeneic HCT (n = 32), autologous HCT (n = 23), and CAR-T therapy (n = 3). The median patient age was 58 years (range, 24 to 77 years), and 64% were males. The median time from HCT/CAR-T therapy to SARS-CoV-2 infection was 17.7 months (range, 0.2 to 201.9 months), and 22% of the patients acquired SARS-CoV-2 within the first 100 days post-HCT/CAR-T therapy. The primary hematologic disorders were plasma cell (36%), myeloid (38%), and lymphoid (26%) malignancies. Myeloablative conditioning was performed in 62% of patients. Donors were autologous (45%), matched sibling (15%), matched unrelated (21%), and haploidentical (19%). Prior history of grade II-IV acute graft-versus-host disease (GVHD), active GVHD, and current immunosuppressive therapy (IST) was noted in 22%, 31%, and 36% of patients, respectively. Concurrent infections were observed in 19%. Lymphopenia (P = .049) and high serum ferritin concentration (P = .020) were associated with mortality. COVID-19 severity was mild in 50% of the patients, moderate in 22%, and severe in 28%. Clinical findings included pneumonia or abnormal chest imaging (in 50%), hypoxia (28%), intensive care unit admission (19%), and mechanical ventilation (10%). Therapies included remdesivir (in 41%), convalescent plasma (35%), dexamethasone (22%), monoclonal antibodies (19%), and tocilizumab (3%). The median duration of viral shedding (positive SARS-CoV-2 PCR) was 7.7 weeks (range, 2 to 18.7 weeks), and 2 patients had a persistent infection for >5 months post-CAR-T therapy. After a median follow-up of 6.1 months (range, 0.5-13.6 months), the mortality rate was 16% in all patients and 28% in allogeneic HCT recipients. Among 9 patients who died, the median survival after SARS-CoV-2 infection was 23 days (range, 14 to 140 days). In survivors with moderate-severe COVID-19, the median time to recovery was 4.2 weeks (range, 1.1 to 24.7 weeks). Among allogeneic HCT recipients, 5 (16%) developed subsequent pulmonary chronic GVHD necessitating systemic steroids and additional IST. Significant predictors of COVID-19 severity included allogeneic HCT (odds ratio [OR], 3.6, 95% confidence interval [CI], 1.2 to 10.8; P = .020), history of grade II-IV acute GVHD (OR, 4.6; 95% CI, 1.10 to 18.86; P = .036) and concurrent IST (OR, 5.9; 95% CI, 1.8 to 19.8; P = .004). HCT and CAR-T cell therapy recipients are at an increased risk of moderate-severe COVID-19 pneumonia and higher mortality with SARS-CoV-2 infection. Our findings confirm the need for continuing vigilance with social distancing and masks, vaccination prioritization, close monitoring, and aggressive treatment of HCT/CAR-T therapy recipients.

Background: There is no standard of care treatment for Acute Myeloid Leukemia (AML) in relapse post-allogeneic hematopoietic stem cell transplant (post-HSCT), with overall 5-year survival about 5-10%. Venetoclax (Ven) is a novel BCL2 inhibitor approved by the FDA for treatment of newly diagnosed AML in combination with hypomethylating agents (HMA) or low dose cytarabine for patients unfit for intensive induction. However, data in relapsed/refractory AML are limited, especially in the post-HSCT setting. In this retrospective study, we reviewed outcomes of patients with AML relapse post-HSCT who received Ven in combination with HMA in a single center. Methods: Charts of 17 patients who had AML relapse post-HSCT treated with combination of Ven and HMA between November 2018 - March 2020 at the University of Kansas Medical Center were reviewed. We utilized descriptive statistics for baseline characteristics and outcomes, and Kaplan-Meier log-rank test for calculating overall survival. Results Seventeen patients received Ven+HMA for AML relapse post-HSCT in our center. At the time of SCT, patients were in first complete remission (CR) (n=15); second CR (n=1) and primary failure induction (1). Median age was 62 at time of relapse (31-71) years, and 8 patients were female (47%). 9 patients (53%) had adverse risk AML (ELN 2017) 8 of them were in CR1 and 1 with primary induction failure. Common mutations included DNMT3a, ASLX-1, TET2 (3); TP53 (2); IDH1/2 (2); NPM1/FLT3 (1); NPM1/IDH2 (1); NPM1 (1 transplanted in CR2); FLT3 (1). 2/17 had received Ven+HMA prior to SCT; 4 patients received HMA alone prior to SCT. 11 patients (65%) were naïve to either Ven or HMA prior to relapse. Median time to relapse was 181 (44-851) days post-HSCT. 9 (53%) patients received Azacitidine+Ven and 8 (47%) received Decitabine+Ven. HMA+Ven was the first line of therapy post-HSCT relapse in 14 patients. 2 had donor lymphocyte infusion (DLI) after either MEC or dacogen but relapsed prior to Ven+HMA. 1 had IDH (2) inhibitor. Patients received median of 2 (1-10) cycles of HMA+Ven. Six (35%) patients achieved complete remission/complete remission with incomplete hematologic recovery (CR/CRi), and 2/6 patients had negative measurable residual disease by multiparameter flow cytometry. Median overall survival was 361 days from relapse (Figure 1). 3/14 patients received subsequent DLI with Ven+HMA. Disease progression was the most common cause of death in 8/9 of patients who died during the follow up period. Most common side effects included neutropenic fever (n=8, 47%) and acute graft versus host disease (aGVHD) (n=5, 30%). 2/5 developed new aGVHD on HMA+Ven with no prior history of aGVHD. However, aGVHD was mainly grade I-II and responsive to therapy. Discussion HMA+Venetoclax demonstrates potential activity in patients with AML relapse post-HSCT with a CR/CRi rate of 35%, comparable to other salvage therapies. There were no unexpected side effect in this high-risk population. Larger studies are needed to confirm efficacy and toxicity in this setting. Disclosures McGuirk: Pluristem Ltd: Research Funding; Kite Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gamida Cell: Research Funding; Bellicum Pharmaceutical: Research Funding; Allo Vir: Consultancy, Honoraria, Research Funding; Juno Therapeutics: Consultancy, Honoraria, Research Funding; Astellas: Research Funding; Fresenius Biotech: Research Funding; Novartis: Research Funding. Lin:Aptevo: Research Funding; Abbvie: Research Funding; Bio-Path Holdings: Research Funding; Celgene: Research Funding; Gilead Sciences: Research Funding; Incyte: Research Funding; Jazz: Research Funding; Mateon Therapeutics: Research Funding; Ono Pharmaceutical: Research Funding; Pfizer: Research Funding; Prescient Therapeutics: Research Funding; Seattle Genetics: Research Funding; Tolero Pharmaceuticals: Research Funding; Trovagene: Research Funding; Genetech-Roche: Research Funding; Celyad: Research Funding; Astellas Pharma: Research Funding.

Patients undergoing high-dose chemotherapy and autologous hematopoietic cell transplantation (auto-HCT) are at risk for multiple morbidities, including mucosal inflammation and neutropenic fever, both related to neutropenia. Evidence from our preclinical work in an umbilical cord blood (UCB) transplantation murine model suggests that treatment with hyperbaric oxygen (HBO) before UCB infusion improves UCB CD34+ cell engraftment by reducing erythropoietin levels. A pilot clinical trial using HBO in patients undergoing UCB transplantation showed improvement in kinetics of blood count recovery. In this study, we evaluated HBO in combination with auto-HCT. Our primary aim was to determine the safety of HBO in this setting and secondarily to determine its efficacy in reducing time to neutrophil and platelet engraftment compared with matched historic controls. Patients with multiple myeloma, non-Hodgkin lymphoma, and Hodgkin disease eligible for auto-HCT were included. On day 0, patients received HBO treatment consisting of exposure to 2.5 atmosphere absolutes for a total of 90 minutes, in a monoplace hyperbaric chamber, breathing 100% oxygen. Six hours after the start of HBO, peripherally mobilized stem/progenitor cells were infused and patients were followed daily for toxicity and blood count recovery. All patients received daily granulocyte colony-stimulating factor starting on day +5 and until absolute neutrophil count (ANC) of ≥1500 or ANC of 500 for 3 consecutive days. A matched historic cohort of 225 patients who received auto-HCT between January 2008 and December 2012 was chosen for comparison and matched on sex, age, conditioning regimen, and disease type. We screened 26 patients for this study; 20 were treated and included in the primary analysis, and 19 completed the HBO therapy and were included in the secondary analysis. Although the median time to neutrophil count recovery was 11 days in both the HBO and control cohorts, the Kaplan-Meier estimates of the full distributions indicate that the time to neutrophil recovery was generally about 1 day sooner for HBO versus historical controls (log-rank P = .005; range, 9 to 13 for HBO patients and 7 to 18 for controls). The median time to platelet count recovery was 16 days (range, 14 to 21) for HBO versus 18 days (range, 11 to 86) for controls (log-rank P © 2019 American Society for Blood and Marrow Transplantation.

7033 Background: The Coronavirus Disease 2019 (COVID-19) has caused over 25 million infections in the US with over 0.4 million deaths. Hematogenic stem cell transplant (HCT) or cellular therapy (CT) recipients have a high risk of mortality with COVID-19 due to profound immune dysregulation. We aimed to assess the outcomes with COVID-19 in HCT/CT recipients. Methods: A single-center prospective study was conducted, including all (n=40) adult HCT/CT patients who were diagnosed with COVID-19 at the University of Kansas from Apr 2020 to Jan 2021. Baseline and disease-related characteristics were ascertained from medical records. Data were analyzed using SPSS version 21 (SPSS Inc, Chicago, IL). Bivariate analyses, using chi-square and t-test, and logistic regression analyses were conducted. Results: The study included 40 COVID-19 patients (72.5% Oct 2020-Jan 2021), including allogeneic HCT (n=25), autologous HCT (n=13) and CAR-T CT (n=2) with median time since HCT/CT of 12.4 (1-201.9), 37.2 (0.4-118.7), and 3.8 (2.8-4.8) months. Seventy percent were Caucasians and 17.5 were Hispanics. Primary hematologic malignancy was myeloid (37.5%), lymphoid (35%) or plasma cell disorder (27.5%). Myeloablative conditioning was performed in 65% of patients. Donors were autologous (37.5%), matched sibling (17.5%), matched unrelated (22.5%) and haploidentical (22.5%). COVID-19 was mild (42.5%), moderate (42.5%) or severe (15%). Clinical findings included pneumonia (62.5%), hypoxia (25%) and ICU admission (17.5%) while therapies included remdesivir (47.5%), convalescent plasma (40%), dexamethasone (25%) and monoclonal antibodies (17.5%). Concurrent cancer treatment, other infections and active GVHD were reported in 25% (all myeloma), 20% and 32.5% of patients. After a median follow-up of 74 days (7-269), the mortality rate was 12.5% in all patients and 20% in allo-HCT patients. Significant predictors of COVID-19 severity included allogeneic HCT, concurrent immune suppression and elevated inflammatory markers. (Table). Conclusions: Hematopoietic stem cell transplant recipients have an increased risk of mortality with COVID-19. Our findings confirm the need for vaccination prioritization, close monitoring, and aggressive treatment in HCT/CT patients.[Table: see text]

e19002 Background: The presence of measurable residual disease (MRD) preceding hematopoietic stem cell transplantation (HSCT) in acute myeloid leukemia (AML) is increasingly recognized as a risk factor for leukemic relapse and decreased survival. Over many years, attempts have been looking at developing tools to detect MRD; this includes multiparametric flow cytometry, quantitative polymerase chain reaction, and most recently, next-generation sequencing (NGS). NGS offers higher sensitivity and detection rate of disease-related gene mutations, thereby potentially improving disease outcomes. Our study sought to review the scientific literature that included NGS‐detected molecular MRD in patients with AML who underwent bone marrow transplantation. Methods: We performed a systematic search using PubMed, Google Scholar, EMBASE, and SCOPUS up until October 2020. Inclusion criteria included articles that reported the association between pre-HSCT MRD detected by NGS and post HSCT outcome in patients with AML. We extracted hazard ratios for the cumulative incidence of relapse (CIR), overall survival (OS) and leukemia free survival (LFS). A random-effect model was utilized to calculate the hazard ratio (HR) with a 95% confidence interval (CI). Results: Six studies met our inclusion criteria. Our meta-analysis showed that the detection of pre-transplant MRD by NGS was associated with increased risk of cumulative incidence of relapse (hazard ratio=2.5, CI= 1.6-3.9, with p-value 2 = 53%, 52%, and 59% for CIR, OS, and LFS, respectively). Conclusions: The application of NGS to detect MRD is a strong predictor of outcome in patients with AML who are undergoing hematopoietic stem cell transplantation. NGS-detected MRD positive status prior to HSCT is indicative of a higher risk of relapse and decreased overall survival in this meta-analysis. Despite the limitations in our study, it demonstrates the value of MRD detection by NGS in HSCT recipients.

e13615 Background: Transplant Survivorship Clinic at our institution serves to improve outcomes and overall health of allogeneic transplant survivors. The COVID19 pandemic allowed for growth of telemedicine in our program. We examine the patterns of use of telehealth and hypothesize that the use of telemedicine allowed continued access to care compared to the era prior to availability. We compared our transplant survivorship clinic data from July- December 2020, when telehealth was well established and compared to July-December 2019. Methods: All patients seen by the survivorship team for end of treatment visits, graft versus host disease assessments and survivorship visits annually between July-December 2019 and July-December 2020 were included. Their zip codes were used to get direct distance to survivorship clinic, average drive time, driving distance and average household income as in zip-codes.com database. Results: Total number of office visits in July-Dec 2019 was 163 visits (0% via telehealth) and in July-Dec 2020 was 228 (66.2% via telehealth). All encounters (telehealth and office visits) were lower in July and August 2020 compared to July and August 2019 but higher in months of September -December 2020 compared to 2019. Comparing all encounters during 7/2019-12/2019 to 7/2020-12/2020, there was no statistically significant difference in median age (58yr vs 60 yr), gender (males: 58% vs 59%), race (non-white: 11% vs 8.7%), median years from transplant (4yr vs 3 yrs), median income of patient neighborhood ($63,735 vs $60,465) and average drive time to center from zip code (40 min vs 51min). Comparison of patients who chose telehealth vs. office visit is summarized in table. While there was no statistically significant difference in age when comparing all encounters in 2019 and 2020, those who chose telehealth were younger (55yrs vs 60yrs, p=0.003). Conclusions: There were higher patient encounters in the 2020 period compared to 2019. Most of these 2020 encounters were via were telehealth, demonstrating the role of telehealth in increasing access. Younger patients appeared to choose telehealth, but telehealth served patients up to the age of 77 yrs. Utilization of telehealth appeared to be irrespective of demographics such as gender, neighborhood income and driving distance to the center. Comparison of telehealth vs office visit for July-December 2019 and 2020.[Table: see text]

Background Donor lymphocyte infusion is an effective treatment for AML relapse post-transplant, but it has the risk of inducing graft versus host disease (GVHD). Isolating and expanding a subset of lymphocytes that contains antigen-specific T cells against AML antigens may increase the potential for a graft-versus-leukemia immune response while reducing the risk of GVHD. We hypothesized that irradiating AML blasts would diminish their immune suppressive capacity while maintaining antigen presentation, resulting in higher activation of antigen-specific CD8+ T cells among peripheral blood mononuclear cells (PBMC) in co-culture. Methods PBMC were isolated from healthy donors’ whole blood. PBMC were co-cultured with live AML K-1 (CRL-2724) cells and irradiated K-1 cells (40 Gy) separately at a 1:2 ratio. Cells were cultured in RPMI complete media supplemented with 10% FBS and IL-2 20 IU/ml. On day 3 of co-culture, CD137 positive cells were labeled by anti-CD137 antibody and isolated by positive selection using a magnetic separation column (MiniMACS; Miltenyi Biotech). PBMC Immunophenotype was evaluated on flow cytometer using surface labels CD3, CD4, CD8, CD137, CD25, CD56 and LAG3 in addition to intracellular IFNγ and FOXP3. Both CD137-selected and unselected cells were expanded in complete media supplemented with IL-2 2000 IU/ml, IL-7 50 ng/ml and IL-15 300 ng/ml. CFSE-labeled K-1 cells were incubated with both CD137-selected and unselected PBMCs separately then viability was measured by 7-ADD on flow cytometry. Results Healthy donor PBMC co-cultured with irradiated K-1 showed significantly higher CD137 expression (9.3% ± 1.21 v. 5.7% ± 3.4; n=7, P Figure 1 A) and IFNγ expression (11.8% ± 3.1 v. 7% ± 3.3; n=7, P=0.012; Figure 1 B) on CD8+ T cells when compared to the live K-1-PBMC co-cultures. There were fewer Tregs (CD4+ CD25+ FOXP3+) in the PBMC co-cultured with irradiated K-1 cells compared to the live K-1-PBMC co-cultures (1.96% ± 0.37 v. 3.39% ± 0.58; n=4, P=0.03; Figure 1 C). CD137-selected cells were isolated and expanded in culture for 2 weeks, and unselected cells were expanded in the same culture conditions. CD137-selected cells expressed more CD3 (60.65% vs 22.8%; n=4, P=0.012) and CD56 (1.6% vs 0.25; n=4, P=0.01) than unselected cells. In comparison to unselected cells. CD137-selected cells showed higher killing of CSFE-labeled AML cells across AML: PBMC ratios (1:5,1:10 and 1:15) at both 24 and 48 hours compared to unselected cells ( Figure 2 ). Conclusion Irradiation of AML cells prior to co-culture increases the expression of activation markers CD137, CD154, and IFNγ. The activation marker CD137 can be used to select a population of cells from healthy donor PBMC. CD137-selected cells can be expanded in vitro and induce efficient killing of AML cells compared to the subset of PBMCs with no CD137 expression.

Background: Mutations in the nucleophosmin (NPM1) gene are associated with better responses to chemotherapy and improved survival among acute myeloid leukemia (AML) patients. However, older AML patients (≥ 60 years old) with NPM1 mutation have worse survival outcomes than younger patients ( Methods: We queried the Beat AML dataset, supported in part by the Leukemia & Lymphoma Society and the OHSU Knight Cancer Institute, for pts with NPM1 gene mutations who did not have adverse-risk ELN 2017 (poor cytogenetic profile or mutations in FLT3, TP53 or ASXL1). Descriptive statistics described baseline characteristics and responses. Kaplan-Meier with log-rank test was used for survival analysis. DNA mutation data were obtained from the exome sequencing and analyzed using the beat AML data viewer (Vizome). RNA exome sequencing data were downloaded. Differential expression of raw count RNA-Seq and gene set enrichment was done using R via limma and ClusterProfiler packages. Results: Among 562 unique patients in the Beat AML umbrella trial, there were 81 patients with newly diagnosed NPM1 mutated AML after exclusion of patients with ELN 2017 adverse-risk category. Among these patients there was 49 older patients (≥ 60 years old) and 32 younger patients ( Exome sequencing data were available for 43 and 30 patients from the older and younger group respectively. There was a median of 6.5 (2-20) and 7 (2-19) mutations in the older and younger group respectively (P=0.78). After exclusion of the benign mutations and variant of unknown significance, the median number of mutations was 4 in both group (P=0.28). Both groups shared only 24 (3.9%) of the gene mutations while there were 334 unique gene mutations in the older group and 262 in the younger group. Most common gene mutations were DNMT3a, TET2, NRAS, WT1, and PTPN11 with frequencies are shown (Figure 1). RNA sequencing data was available for 26 patients from the older group and 18 patients from the younger group. We explored the gene expression profile of the top 1000 differentially expressed genes in both groups after adjustment. There was distinctive clustering of the gene expression profile between the two groups (Figure 2). Gene set enrichment analysis identified multiple immune-related pathways among the highly enriched gene sets in both groups but with different functions in the two groups. There was significant gene set enrichment in the TGFβ signaling in the older patient group which is associated with immune suppression and microenvironment modulation. While the younger group showed significant enrichment in the TNFa, IL17, PI3K-AKT signaling which are associated with inflammation. Conclusion: Older AML patients with NPM1 mutations, and no adverse risk features, had lower rate of complete responses and a trend towards a worse survival compared to younger patients. Whole exome sequencing did not show increased mutational burden. However, 96% of the mutated genes were different between the two groups as were the gene expression profiles. Gene set enrichment analysis showed contrasting enriched immune-related pathways between both groups. The immunosuppressive TGFβ signaling gene set were significantly enriched in the older group while the inflammatory TNFa, IL17, PI3K-AKT signaling gene sets were significantly enriched in the younger group. Older AML patient with NPM1 mutations have distinctive genomic landscape compared to the younger patient which may explain in part the worse clinical outcomes in the absence of other adverse risk features. Disclosures Lin: Jazz Pharmaceuticals: Honoraria; Pfizer: Membership on an entity's Board of Directors or advisory committees.

Allogeneic stem cell transplantation (SCT) is a potentially curative treatment for MDS. Besides the innate heterogeneity of MDS, intensity of the conditioning regimen (myeloablative (MAC) versus reduced intensity/non-myeloablative (RIC)), specific agents used in conditioning, donor and source of stem cells and GVHD prevention regimens further influence outcomes. We sought to determine how conditioning regimens influenced MDS subgroup cohort outcomes. We retrospectively analyzed outcomes of 107 MDS patients (63 male and 44 females) with median age 61.8 (17-73 years) who underwent allogeneic SCT at our institution between 2008 and 2017. For the purposes of this report, patients were grouped according to WHO classification into non-RAEB (RCMD, RA, RARS RCUD or 5q deletion, n=49) and RAEB (RAEB1 and RAEB2, n=58) categories. Median time from MDS diagnosis to transplantation was 139 days (20-3175). No patients were in complete remission (CR) at time of SCT. Allogeneic donor types were matched related, matched unrelated, haplo-identical and cord blood in 30, 65, 10 and 2 patients, respectively. Stem cell source was peripheral blood (91 patients) and bone marrow in 14. Forty patients (median age 52.2 (17-61) years) underwent MAC and 67 (median age 63.7 (23-73) years) RIC. Twelve patients died within 100 days of transplantation, 3 due to disease progression, 5 to acute GVHD, and 4 to other transplant-related causes. Median overall survival (OS) for all 107 patients was 1.3 years with 54%, 47% and 40% alive at 1, 2 and at 5 years. OS was slightly higher in patients undergoing RIC with OS of 57%, 48% and 40% (median 1.532 years) versus 50%, 40% and 38% with MAC (median 0.92 years) at the same time points (p>0.1). Median OS of the 49 patients with non-RAEB and 58 patients with RAEB MDS was 3.01 years versus 0.92 years (p>0.1). GVHD was the most frequent cause of death (46%), followed by relapse/progression (28%), infection (14%) and other (12%). Of 29 patients undergoing RIC with non-RAEB MDS, median OS was 3.78 years while for 38 RAEB patients it was 1.17 years (p>0.1). See table for OS according to conditioning regimen and WHO classification. For MAC, in 20 non-RAEB patients median OS was 2.2 years while the median OS was 0.69 years for 20 RAEB patients (p>0.1). CR after SCT was achieved in 57 patients (53%), 33 receiving RIC (CR 49.2%) and 24 receiving MAC (CR 60%). Seven patients subsequently relapsed, 4 RIC and 3 MAC. Of the non-RAEB patients achieving CR, median OS in the 16 patients treated with 111 RIC was not reached and in 14 patients receiving MAC, median OS was 3.75 years (p>0.1). For the 27 RAEB patients achieving CR, median OS was 4.4 years in 17 patients treated with RIC versus not reached in 10 patients treated with MAC. Overall, death in non-RAEB patients occurred in 26/49 (53%) compared to 38/58 (66%) RAEB patients and in 40/67 (59%) patients undergoing RIC versus 25/40 (63%) MAC patients (p>0.5). The hematopoietic transplant comorbidity index did not predict OS outcomes in these MDS patients (p>0.1) and the cytogenetic score according to the IPSS-R "very good -very poor" groups indicated no differences in OS in the non-RAEB patients but in RAEB patients significant differences according to the cytogenetic score was evident (P Conclusions: In this retrospective analysis of MDS patients undergoing allogeneic SCT, achieving CR led to improved survival. In non-RAEB MDS patients achieving CR, OS was similar irrespective of conditioning intensity (RIC or MAC). Furthermore, outcomes did not differ in RAEB patients who achieved CR according to intensity of conditioning regimen. However, those receiving MAC had not reached median OS at 5 years. The outcomes in this analysis indicate that improvement in the incidence of deaths due to GVHD would likely have the greatest impact in improving survival in MDS patients undergoing allogeneic transplantation. Table Disclosures Abhyankar: Therakos: Other: Consulting, Speakers Bureau; Incyte: Speakers Bureau. Lin:Jazz Pharmaceuticals: Honoraria; Pfizer: Membership on an entity's Board of Directors or advisory committees. Yacoub:Incyte: Consultancy, Speakers Bureau. Ganguly:Kite Pharma: Honoraria, Other: Advisory Board; Seattle Genetics: Speakers Bureau; Janssen: Honoraria, Other: Advisory Board; Daiichi Sankyo: Research Funding. McGuirk:Pluristem Ltd: Research Funding; Gamida Cell: Research Funding; Kite Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bellicum Pharmaceuticals: Research Funding; Astellas: Research Funding; Fresenius Biotech: Research Funding; Novartis: Research Funding; Juno Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ArticulateScience LLC: Other: Assistance with manuscript preparation.

e18525 Background: Several recurrent genetic mutations have been described in acute myeloid leukemia (AML), which have both prognostic and therapeutic implications. Recurrent mutations in the Neurofibromin 1 ( NF1) gene are reported in 1-5 % of AML patients; however, there are limited data regarding its prognostic implications. Here, we report the outcomes for patients with newly diagnosed AML with a somatic NF1 mutation at our center. Methods: A retrospective chart review included patients with newly diagnosed AML at KUMC from 01/2016 through 09/2018. All patients had targeted next-generation sequencing (NGS) at diagnosis. Baseline characteristics were compared between patients with NF1 mutations and those who were wild-type using Fisher’s exact test for categorical variables, and the Wilcoxon rank-sum test for continuous variables. The primary outcome was overall survival (OS), which was measured from the time of diagnosis to the time of death from any cause. A stepwise Cox proportional-hazard model was used to adjust for potential confounders. Results: Data on 110 patients were included. Out of the 110 patients, 15 (13.6%) had a delectable NF1 mutation, while 95 (86.4%) patients were NF1 wild-type. The baseline characteristics of the two groups are displayed below. Median OS for patients with an NF1 mutation was 7.3 months, while it was 18.4 months for patients with NF1 wild-type, Log-rank test p-value 0.02. After adjusting for potential confounders, including age, ELN risk category, induction regimen, presence of other mutations such as TP53, the hazard of death remained significantly higher for patients with NF1 mutations, HR 2.4, CI (1.05-5.6), p-value 0.04. Conclusions: In this single-center retrospective study, the presence of a NF1 mutation was associated with worse overall survival in patients with newly diagnosis AML. [Table: see text]

Liu, Chunsheng [el alt.] 19 p.-14 fig., In the tumor microenvironment, TGF-β induces transdifferentiation of quiescent pericytes and related stromal cells into myofibroblasts that promote tumor growth and metastasis. The mechanisms governing myofibroblastic activation remain poorly understood, and its role in the tumor microenvironment has not been explored. Here, we demonstrate that IQ motif containing GTPase activating protein 1 (IQGAP1) binds to TGF-β receptor II (TβRII) and suppresses TβRII-mediated signaling in pericytes to prevent myofibroblastic differentiation in the tumor microenvironment. We found that TGF-β1 recruited IQGAP1 to TβRII in hepatic stellate cells (HSCs), the resident liver pericytes. Iqgap1 knockdown inhibited the targeting of the E3 ubiquitin ligase SMAD ubiquitination regulatory factor 1 (SMURF1) to the plasma membrane and TβRII ubiquitination and degradation. Thus, Iqgap1 knockdown stabilized TβRII and potentiated TGF-β1 transdifferentiation of pericytes into myofibroblasts in vitro. Iqgap1 deficiency in HSCs promoted myofibroblast activation, tumor implantation, and metastatic growth in mice via upregulation of paracrine signaling molecules. Additionally, we found that IQGAP1 expression was downregulated in myofibroblasts associated with human colorectal liver metastases. Taken together, our studies demonstrate that IQGAP1 in the tumor microenvironment suppresses TβRII and TGF-β dependent myofibroblastic differentiation to constrain tumor growth., We thank Kah Whye Peng and Yasuhiro Ikeda for providing reagents. The authors also acknowledge grant K01 CA118722, a 2009 Research Early Career Development Award (Mayo Clinic),the P/F Award and Clinical Core (P30 NIDDK 84567), and grants R01 CA160069 to N. Kang, R01 DK059615 to V.H. Shah, and; R01 NS051746 to G.S. Bloom.

Background: The curative potential of allogeneic hematopoietic stem cell transplant (SCT) for acute myeloid leukemia (AML) depends in part on the graft-versus-leukemia (GVL) cellular immune response. Mechanisms of resistance to GVL and methods to overcome post-SCT relapse are a critical focus of research. AML blasts can inhibit activation and proliferation of immune cells in culture. We hypothesized that irradiating AML blasts would diminish their immune suppressive capacity while maintaining antigen presentation, leading to higher activation of CD8+ T cells among peripheral blood mononuclear cells (PBMC) in co-culture. Furthermore, we investigated the capacity of live and irradiated AML blasts to induce expression of immune checkpoints on CD8+ T cells in co-culture, focusing on Lymphocyte-activation gene 3 (LAG3) which interacts with class II MHC. Methods: PBMC were isolated from healthy donors in compliance with an IRB-approved protocol. PBMC were co-cultured with live human AML K-1 cells (CRL-2724) and irradiated K-1 cells (40 Gy) at the following ratios: 1:1, 1:2, 1:4 and 1:8. Cells were cultured in RPMI complete media supplemented with 10% FBS and IL-2 20 IU/ml. On day 3 of co-culture, immunophenotypic characterization of T cells was performed on an Attune NxT flow cytometer using the following antibody markers: CD3, CD4, CD8, CD25, CD137, CD154, PD-1, TIM3, TIGIT, and LAG3. PBMC were fixed and permeabilized prior to intracellular staining of IFNg and FOXP3. Regulatory T cells (Tregs) were identified as CD4+ CD25+ FOXP3+. To correlate the expression of the genes encoding for IFNg, LAG3, PD1, and antigen presentation molecules in the tumor microenvironment, we analyzed RNA sequencing data from The Cancer Genome Atlas (NCI TCGA) AML database. Associations were determined by Spearman's correlation and K-means clustering. Results: PBMC co-cultured with irradiated AML K-1 showed significant higher IFNg expression (11.8% ± 3.1 v. 7% ± 3.3; n=7, P=0.012) and higher CD137 (4-1BB) expression (9.3% ± 1.21 v. 5.7% ± 3.4; n=7, P Conclusion: In our in vitro model, LAG3 upregulation correlates with decreased activation of CD8+ cells and higher Tregs when healthy donor PBMC are co-cultured with AML K-1 cells. Antibody-mediated blocking of LAG3 may potentially reverse the suppression of CD8+ T cells by AML K-1 cells and produce fewer Tregs. Bioinformatic analysis of TCGA database confirmed a positive correlation between LAG3 transcript levels and expression of both immune activation and antigen presentation genes. LAG3 transcript levels are higher in unfavorable-risk AML. Figure. Figure. Disclosures Lin: Jazz Pharmaceuticals: Honoraria.

High-dose chemotherapy and autologous hematopoietic cell transplantation (Auto-HCT) is an established therapy for patients with multiple myeloma and lymphomas. Post-transplant complications during the neutropenia phase include pancytopenia requiring transfusions and G-CSF support, mucositis and infectious complications. Previously, we have demonstrated that hyperbaric oxygen therapy (HBO) given day 0 prior to transplant reduced erythropoietin (EPO) levels and improved engraftment in umbilical cord blood transplantation. Subsequently, we conducted a pilot trial to study HBO effects EPO levels and engraftment in Auto-HCT setting. Herein, we review HBO effects on Auto-HCT post-transplant complications. Methods: Charts of patient who underwent HBO treatment prior to Auto-HCT on our pilot study and matched historic controls were retrospectively reviewed for post-transplant transfusion requirements, G-CSF support, mucositis and infectious complications Results: Nineteen patients completed HBO therapy and were compared to 118 patients in our historic cohort. Basic patient characteristics are listed in table-1. Average days of G-CSF use was 6.2 days in our HBO cohort compared to 9.16 days in the historic cohort (P=0.0007). Average number of transfused packed red cells was 2.1 and 2.58 units (P=0.22), while average number of platelet unit transfusions was 2.5 and 3.2 (P=0.17) in the HBO and historic cohorts, respectively. Mucositis incidence was 26.3% in the HBO cohort compared to 59.3% in controls (P=0.008). Similarly, the rate of neutropenic fever was 47% in the HBO cohort vs. 65% in controls (P=0.11). The rate of admissions, on the other hand, was 31.5% in the HBO cohort compared to 23.7% in controls (P=0.31) with an average length of hospital stay of 6.6 days in the HBO cohort compared to 7.68 days in controls (P=0.31). Conclusions: HBO therapy prior to Auto-HCT is associated with lower G-CSF use and lower incidence of mucositis in our retrospective study. Prospective studies are needed to determine HBO effects on Auto-HCT post-transplant complications. Disclosures Ganguly: Onyx: Speakers Bureau; Seattle Genetics: Speakers Bureau; Janssen: Research Funding.

e19004Background: High-dose chemotherapy and autologous hematopoietic cell transplantation (Auto-HCT) is associated with neutropenia, anemia and thrombocytopenia in the post-transplant period. The ...

Introduction: Transforming growth factor beta (TGF-β) within the tumor microenvironment induces transdifferentiation of quiescent pericytes and related stromal cells into myofibroblasts that promote tumor growth. However mechanisms governing TGF-β mediated myofibroblastic activation remain poorly understood. IQ motif containing GTPase activating protein 1 (IQGAP1) exerts diverse cellular functions, but its role in the tumor microenvironment is unexplored. In this study, we tested a hypothesis that IQGAP1 may interact with TGF-β receptor II (TβRII) and regulate its signaling in mesenchymal-type cells that activate into tumor associated myofibroblasts such as hepatic stellate cells (HSCs), which are resident liver pericytes, and that IQGAP1 of HSCs regulates liver metastatic growth. Experimental procedures: Retroviral and lentiviral based vectors were used to deliver TβRII, IQGAP1 or IQGAP1 shRNA into human primary HSCs. IQGAP1/TβRII interactions were determined by immunofluorescence staining, immunoprecipitation, in vitro GST pull down and in vitro protein binding assays. TGF-β1 activation of HSCs into myofibroblasts was determined by α-SMA immunofluorescence and Western Blot analyses for α-SMA, fibronectin and P-Smad2. The role of stellate cell IQGAP1 in tumorigenesis was assessed by in vitro assays of conditioned media, a HSC/tumor cell co-implantation mouse model and experimental liver metastasis model performed on IQGAP1 knockout mice. Additionally, IQGAP1 protein levels in the myofibroblasts of 29 human colorectal liver metastases were investigated by immunofluorescence staining. Results: IQGAP1 is recruited to TβRII by TGF-β1 with the C-terminal a.a. 1503-1657 region of IQGAP1 mediating IQGAP1/TβRII binding. Through scaffolding the E3 ubiquitin ligase Smurf1 and TβRII, IQGAP1 promotes ubiquitination, lysosomal and proteasomal degradation of TβRII, thus suppressing TβRII and TGF-β1 activation of HSCs into myofibroblasts in vitro. In mice, co-implantation of IQGAP1 knockdown HSCs promotes myofibroblastic activation of HSCs, tumor implantation and growth. In an experimental liver metastasis model, IQGAP1 deficiency in the tumor microenvironment promotes myofibroblastic activation and liver metastatic growth. Indeed, IQGAP1 knockdown in HSCs upregulates paracrine signaling molecules such as stromal derived factor 1 (SDF-1/CXCL12) and hepatic growth factor (HGF) that confer a stimulatory effect on proliferation, migration and survival of tumor cells. Additionally, we found that 24 out of 29 colorectal cancer patients display varying degrees of reduction of IQGAP1 protein in the myofibroblasts of their liver metastases as compared to IQGAP1 expression levels observed in activated HSCs and portal myofibroblasts of the adjacent non-tumorous control liver. Conclusion: Our studies demonstrate that IQGAP1 in the tumor microenvironment suppresses TβRII and the TGFβ1 dependent myofibroblastic activation switch with these events constraining tumor growth and metastasis. Citation Format: Chunsheng Liu, Haitham Abdelhakim, Vijay H. Shah, Ningling Kang. IQGAP1 in the tumor microenvironment suppresses TGF-beta mediated myofibroblastic activation and ensuing tumor growth. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr B19.