Search

Purpose: The aim of this study is to determine immune-related biomarkers to predict effective antitumor immunity in myelodysplastic syndrome (MDS) during immunotherapy (IMT, αCTLA-4, and/or αPD-1 antibodies) and/or hypomethylating agent (HMA). Experimental Design: Peripheral blood samples from 55 patients with MDS were assessed for immune subsets, T-cell receptor (TCR) repertoire, mutations in 295 acute myeloid leukemia (AML)/MDS-related genes, and immune-related gene expression profiling before and after the first treatment. Results: Clinical responders treated with IMT ± HMA but not HMA alone showed a significant expansion of central memory (CM) CD8+ T cells, diverse TCRβ repertoire pretreatment with increased clonality and emergence of novel clones after the initial treatment, and a higher mutation burden pretreatment with subsequent reduction posttreatment. Autophagy, TGFβ, and Th1 differentiation pathways were the most downregulated in nonresponders after treatment, while upregulated in responders. Finally, CTLA-4 but not PD-1 blockade attributed to favorable changes in immune landscape. Conclusions: Analysis of tumor–immune landscape in MDS during immunotherapy provides clinical response biomarkers.

Purpose:The aim of this study is to determine immune-related biomarkers to predict effective antitumor immunity in myelodysplastic syndrome (MDS) during immunotherapy (IMT, αCTLA-4, and/or αPD-1 antibodies) and/or hypomethylating agent (HMA).Experimental Design:Peripheral blood samples from 55 patients with MDS were assessed for immune subsets, T-cell receptor (TCR) repertoire, mutations in 295 acute myeloid leukemia (AML)/MDS-related genes, and immune-related gene expression profiling before and after the first treatment.Results:Clinical responders treated with IMT ± HMA but not HMA alone showed a significant expansion of central memory (CM) CD8+ T cells, diverse TCRβ repertoire pretreatment with increased clonality and emergence of novel clones after the initial treatment, and a higher mutation burden pretreatment with subsequent reduction posttreatment. Autophagy, TGFβ, and Th1 differentiation pathways were the most downregulated in nonresponders after treatment, while upregulated in responders. Finally, CTLA-4 but not PD-1 blockade attributed to favorable changes in immune landscape.Conclusions:Analysis of tumor–immune landscape in MDS during immunotherapy provides clinical response biomarkers.

Figure S2. Schema for study design

Table S8. Genes used for gene set analysis

Venetoclax (VEN), in combination with low dose cytarabine (AraC) or a hypomethylating agent, is FDA approved to treat acute myeloid leukemia (AML) in patients who are over the age of 75 or cannot tolerate standard chemotherapy. Despite high response rates to these combination therapies, most patients succumb to the disease due to relapse and/or drug resistance, providing an unmet clinical need for novel therapies to improve AML patient survival. ME-344 is a potent isoflavone with demonstrated inhibitory activity toward oxidative phosphorylation (OXPHOS) and clinical activity in solid tumors. Given that OXPHOS inhibition enhances VEN antileukemic activity against AML, we hypothesized that ME-344 could enhance the anti-AML activity of VEN. Here we report that ME-344 synergized with VEN to target AML cell lines and primary patient samples while sparing normal hematopoietic cells. Cooperative suppression of OXPHOS was detected in a subset of AML cell lines and primary patient samples. Metabolomics analysis revealed a significant reduction of purine biosynthesis metabolites by ME-344. Further, lometrexol, an inhibitor of purine biosynthesis, synergistically enhanced VEN-induced apoptosis in AML cell lines. Interestingly, AML cells with acquired resistance to AraC showed significantly increased purine biosynthesis metabolites and sensitivities to ME-344. Furthermore, synergy between ME-344 and VEN was preserved in these AraC-resistant AML cells. These results translated into significantly prolonged survival upon combination of ME-344 and VEN in NSGS mice bearing parental or AraC-resistant MV4-11 leukemia. This study demonstrates that ME-344 enhances VEN antileukemic activity against preclinical models of AML by suppressing OXPHOS and/or purine biosynthesis.

Although venetoclax-based lower-intensity regimens have greatly improved outcomes for older adults with acute myeloid leukemia (AML) who are unfit for intensive chemotherapy, the optimal induction for older patients with newly diagnosed AML who are suitable candidates for hematopoietic stem cell transplant (HSCT) is controversial. We retrospectively analyzed post-HSCT outcomes of 127 patients ≥60 years of age who received induction therapy at our institution with intensive chemotherapy (IC, n=44), lower-intensity therapy (LIT) without venetoclax (n=29) or LIT with venetoclax (n=54) and who underwent allogeneic HSCT in first remission. The 2-year relapse-free survival with LIT with venetoclax was 60%, versus 54% with IC and 41% with LIT without venetoclax, and 2-year overall survival for LIT with venetoclax was 72%, versus 58% with IC and 41% with LIT without venetoclax. The benefit to LIT with venetoclax induction was greatest in patients with adverse-risk AML (2-year OS 74%, 46%, and 29%, respectively). Induction with LIT, with or without venetoclax, was associated with the lowest rate of non-relapse mortality (NRM) (2-year NRM 17% versus 27% with IC; P=0.04). By multivariate analysis, type of induction therapy did not significantly impact any of the post-HSCT outcomes evaluated; hematopoietic cell transplantation-specific comorbidity index (HCT-CI) was the only factor that independently predicted for RFS and OS. LIT plus venetoclax followed by HSCT is feasible treatment strategy in older, fit, and HSCT-eligible patients with newly diagnosed AML and may be particularly beneficial in those with adverse-risk disease.

RASpathway mutations, which are present in 30% of patients with chronic myelomonocytic leukemia (CMML) at diagnosis, confer a high risk of resistance to and progression after hypomethylating agent (HMA) therapy, the current standard of care for the disease. Using single-cell, multi-omics technologies, we sought to dissect the biological mechanisms underlying the initiation and progression ofRASpathway–mutated CMML. We found thatRASpathway mutations induced the transcriptional reprogramming of hematopoietic stem and progenitor cells (HSPCs), which underwent proliferation and monocytic differentiation in response to cell-intrinsic and -extrinsic inflammatory signaling that also impaired immune cells’ functions. HSPCs expanded at disease progression and relied on the NF-KB pathway effector MCL1 to maintain their survival, which explains why patients withRASpathway– mutated CMML do not benefit from BCL2 inhibitors such as venetoclax. Our study has implications for developing therapies to improve the survival of patients withRASpathway– mutated CMML.

Supplementary Data from Targeting the EIF2AK1 Signaling Pathway Rescues Red Blood Cell Production in SF3B1-Mutant Myelodysplastic Syndromes With Ringed Sideroblasts

SF3B1 mutations, which occur in 20% of patients with myelodysplastic syndromes (MDS), are the hallmarks of a specific MDS subtype, MDS with ringed sideroblasts (MDS-RS), which is characterized by the accumulation of erythroid precursors in the bone marrow and primarily affects the elderly population. Here, using single-cell technologies and functional validation studies of primary SF3B1-mutant MDS-RS samples, we show that SF3B1 mutations lead to the activation of the EIF2AK1 pathway in response to heme deficiency and that targeting this pathway rescues aberrant erythroid differentiation and enables the red blood cell maturation of MDS-RS erythroblasts. These data support the development of EIF2AK1 inhibitors to overcome transfusion dependency in patients with SF3B1-mutant MDS-RS with impaired red blood cell production.Significance:MDS-RS are characterized by significant anemia. Patients with MDS-RS die from a shortage of red blood cells and the side effects of iron overload due to their constant need for transfusions. Our study has implications for the development of therapies to achieve long-lasting hematologic responses.This article is highlighted in the In This Issue feature, p. 476

Table S1. Baseline characteristics of patients Table S2-S7. The 40 most statistically significant differential expression results

When multiple haploidentical donors are available for transplantation, those of younger generations are generally selected over those of older generations. However, it is unclear who is the optimal donor when selecting candidates from within a generation, such as father versus mother, son versus daughter, or brother versus sister. Although traditionally male donors are favored over female donors, particularly for male recipients, and significant associations of individual HLA mis(matches) on outcomes are being increasingly recognized, the hierarchy of factors for donor selection is indeterminate. To assess whether HLA factors take precedence over non-HLA factors and to isolate the influence of specific characteristics on outcomes, we analyzed 412 patients stratified by donor relationship: child donor (son [n = 202] versus daughter [n = 96]), parent (father [n = 28] versus mother [n = 29]), and sibling (noninherited maternal [NIMA; n = 29] versus paternal [NIPA; n = 28] mismatched). Among siblings, NIMA mismatch was associated with a lower risk of acute graft-versus-host disease (aGVHD); B-leader mismatch was associated with high nonrelapse mortality (NRM), poor progression-free survival, and a trend toward poor overall survival (OS), whereas A-mismatch was associated with lower aGVHD. Among parent donors, the relationship did not impact any outcome; B-leader mismatch was associated with higher NRM and a trend toward poor OS, whereas A-mismatch was associated with lower NRM and improved progression-free survival and OS. Among child donors, no individual HLA mismatch was predictive of any outcome, and daughter donors were not associated with any adverse outcomes in multivariate analyses. Our data suggest that certain HLA factors may be more significant in some cases and should be given priority over simply selecting a donor based on relationship/sex.

Recurrence of MRD in AML is associated with imminent relapse unless intervened upon. Change in chemotherapy regimen and/or immediate transplant improve outcomes.

The use of post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis is increasing in patients undergoing HLA-matched sibling (MSD) or unrelated (MUD) donor hematopoietic cell transplantation (HCT), but data about its comparative efficacy against the traditional GVHD prophylaxis are scarce. Two broad questions assessed in this study were (a) comparison of PTCy-based GVHD prophylaxis versus Tac/MTX (without ATG) in the MSD and (b) comparison of PTCy-based GVHD prophylaxis versus Tac/MTX (with ATG) in the MUD group. This retrospective single-center study analyzed the outcomes of 964 patients who received Tac/MTX (n = 578) versus PTCy-based (n = 386) GVHD prophylaxis. All MUD recipients in the Tac/MTX group also received ATG; thus separate analyses were conducted for MSD (n = 412) and MUD (n = 552) cohorts. In the MUD cohort, 306 patients received Tac/MTX/ATG and 246 received PTCy-based GVHD prophylaxis. In the MSD cohort, 272 received Tac/MTX and 140 received PTCy-based prophylaxis. Both PTCy groups included somewhat older patients than the Tac/MTX groups and more patients had myeloid malignancy (85%-90% versus 59%-64%, respectively). A majority of patients in all groups received myeloablative conditioning and peripheral blood graft. Both PTCy groups had a significantly delayed neutrophil engraftment, higher risk of hemorrhagic cystitis, and higher risk of bacterial infections than the Tac/MTX groups. The risks of viral infections and related deaths were significantly higher in Tac/MTX group in the MUD cohort. In multivariate analysis, the risk of grade III-IV acute GVHD was similar in PTCy and Tac/MTX groups in both MSD and MUD cohorts, but the risk of chronic GVHD was significantly lower with PTCy in the MSD cohort. PTCy was associated with a significantly lower risk of non-relapse mortality and better progression-free survival in the MUD. PTCy was associated with improved GVHD-free relapse-free survival in both MSD and MUD groups. Our data suggest a benefit of using PTCy-based GVHD prophylaxis in both MSD (versus Tac/MTX) and MUD (versus Tac/MTX/ATG) HCT.

BackgroundAcute myeloid leukemia (AML) stem cells (LSCs) are capable of surviving current standard chemotherapy and are the likely source of deadly, relapsed disease. While stem cell transplant serves as proof-of-principle that AML LSCs can be eliminated by the immune system, the translation of existing immunotherapies to AML has been met with limited success. Consequently, understanding and exploiting the unique immune-evasive mechanisms of AML LSCs is critical.MethodsAnalysis of stem cell datasets and primary patient samples revealed CD200 as a putative stem cell–specific immune checkpoint overexpressed in AML LSCs. Isogenic cell line models of CD200 expression were employed to characterize the interaction of CD200+AML with various immune cell subsets both in vitro and in peripheral blood mononuclear cell (PBMC)–humanized mouse models. CyTOF and RNA-sequencing were performed on humanized mice to identify novel mechanisms of CD200-mediated immunosuppression. To clinically translate these findings, we developed a fully humanized CD200 antibody (IgG1) that removed the immunosuppressive signal by blocking interaction with the CD200 receptor while also inducing a potent Fc-mediated response. Therapeutic efficacy of the CD200 antibody was evaluated using both humanized mice and patient-derived xenograft models.ResultsOur results demonstrate that CD200 is selectively overexpressed in AML LSCs and is broadly immunosuppressive by impairing cytokine secretion in both innate and adaptive immune cell subsets. In a PBMC-humanized mouse model, CD200+leukemia progressed rapidly, escaping elimination by T cells, compared with CD200−AML. T cells from mice with CD200+AML were characterized by an abundance of metabolically quiescent CD8+central and effector memory cells. Mechanistically, CD200 expression on AML cells significantly impaired OXPHOS metabolic activity in T cells from healthy donors. Importantly, CD200 antibody therapy could eliminate disease in the presence of graft-versus-leukemia in immune competent mice and could significantly improve the efficacy of low-intensity azacitidine/venetoclax chemotherapy in immunodeficient hosts.ConclusionsOverexpression of CD200 is a stem cell–specific marker that contributes to immunosuppression in AML by impairing effector cell metabolism and function. CD200 antibody therapy is capable of simultaneously reducing CD200-mediated suppression while also engaging macrophage activity. This study lays the groundwork for CD200-targeted therapeutic strategies to eliminate LSCs and prevent AML relapse.

Adapted from the haploidentical hematopoietic stem cell transplantation (HCT) literature, post-transplantation cyclophosphamide (PTCy) is being used increasingly with HLA-matched donors, generally with a calcineurin inhibitor, such as tacrolimus (Tac), and with or without mycophenolate mofetil (MMF). Owing to its immunosuppressive and potentially antitumor and antimicrobial properties, MMF is an attractive drug; the benefit gained when it is used with PTCy/Tac remains unclear, however. To assess this, we compared PTCy/Tac (n = 242) and PTCy/Tac/MMF (n = 144) regimens in recipients of HLA-matched donor transplantation. In multivariate analysis, the PTCy/Tac/MMF group had a significantly higher risk of grade II-IV acute graft-versus-host disease (aGVHD) (hazard ratio [HR], 2.1; 95% confidence interval [CI], 1.6 to 2.8; P.001), and steroid-refractory/dependent aGVHD (HR, 4.8; 95% CI, 2.4 to 9.6; P.001), yet a significantly lower risk of relapse (HR, .5; 95% CI, .3 to .9; P = .009) and better progression-free survival (PFS) (HR, .7; 95% CI, .5 to .9; P = .04). There were no differences in the risk of grade III-IV aGVHD, chronic graft-versus-host disease (cGVHD), nonrelapse mortality, or overall survival. MMF was associated with prolonged neutrophil engraftment by 2 days and an elevated risk of bacterial infection. In an exploratory stool microbiome analysis (n = 16), we noted a higher relative abundance of β-glucuronidase-producing bacteria in the MMF group, which may have a role in the pathogenesis of MMF-related GVHD. Our data suggest that the addition of MMF to PTCy/Tac for HLA-matched donor HCT does not provide any advantage for GVHD prevention. Further studies are needed to decipher this mechanism and understand its role with PTCy-based prophylaxis.

Recent clinical observations that some coronavirus infections induced complete remissions in lymphoma patients emphasized again the potential of cancer virotherapy. Infection of cancer cells with oncolytic viruses reshapes the tumor microenvironment by activating anti-viral and anti-tumor immunity. A phase 1 clinical trial using oncolytic adenovirus Delta-24-RGD (DNX-2401) to treat recurrent malignant gliomas demonstrated activation of CD8+ T-cells and significant clinical benefits for a subset of patients. However, both anti-virus and anti-tumor immune responses are contingent on the activation of respective clones of CD8+ T-cells, which compete for clonal expansion. Thus, overexpansion of T-cells against viral antigens reduces the frequency of subdominant clones against tumor antigens. We hypothesized that inducing immune tolerance for viral antigens will decrease anti-viral immunity and in turn derepress anti-tumor immunity, resulting in enhanced efficacy of cancer virotherapy. In this work, we used nanoparticles encapsulating adenoviral antigens E1A, E1B and hexon that distributed to liver resident macrophages (P Citation Format: Dong Ho Shin, Hong Jiang, Debora Kim, Teresa T. Nguyen, Sagar Sohoni, Xuejun Fan, Yanhua Yi, Arie C. Van Wieren, Gheath Al-Atrash, Chantale Bernatchez, Ramon Alemany, Marta Alonso, Frederick Lang, Candelaria Gomez-Manzano, Bulent Ozpolat, Juan Fueyo. Redirection of anti-virus immunity towards anti-tumor immunity using nanoparticle-induced immune tolerance for oncolytic adenovirus therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3559.

Background: In the Phase III randomized trial (SWOG Lung-MAP S1400I non match trial), adding ipilimumab (I) to nivolumab (N) did not improve survival of patients with advanced, pretreated, immune checkpoint inhibitor naive lung squamous cell carcinoma (SCC). The I+N combination demonstrated superiority in patients with a tumor mutation burden (TMB) ≥10 mt/MB and PD-L1 expression Methods: RNA extracted from baseline FFPE samples from 66/252 patients enrolled in the S1400I trial was received from the SWOG bank with 28 samples considered inadequate due to low input RNA. 38 samples were run on the ncounter platform using the PanCancer Immune Profiling panel using the manufacturer’s instructions with the addition of Human Reference RNA control. Data were processed and normalized using nSolver. All samples passed the post run QC with no batch effect. Using a log-rank test on dichotomized normalized data, we performed time to event analysis to identify genes that correlated with overall survival (OS) and PFS (Progression Free Survival) for all 38 samples and for each arm (23 N and 15 I+N). We ran a Cox model using significant genes identified independently and in association with TMB≥10 and PD-L1 ≥5 thresholds identified in the clinical studies. TIMER and nSolver advanced analysis were used to infer immune cells that correlated to clinical outcomes. Results: We observed that BLNK, CD163, FCGR2A associated with increased OS (p Conclusion: Despite a small dataset, this analysis shows a potential advantage in PFS and OS with increased presence of immune cells including exhausted CD8+ T cells and genes associated with myeloid cells. Validation of these findings is warranted and may refine patient populations that would benefit from this combination strategy. Acknowledgments: Scientific and financial support: U10CA180888, U10CA180819, U24CA224285, U24CA224316, PACT, PPP and FNIH Citation Format: Dzifa Y. Duose, Jiexin Zhang, Mary Redman, Baili Zhang, Ethan Cerami, James Lindsay, Joyce Yu, Roshni Biswas, Stephen Van Nostrand, Radim Moravec, Rajyalakshmi Luthra, Gheath Al-Atrash, Karen Kelly, Roy Herbst, Ignacio Wistuba, Scott Gettinger, Lyudmila Bazhenova, J. Jack Lee, Jianjun Zhang, Cara Haymaker. Immune gene expression signatures associated clinical benefit from nivolumab and ipilimumab for previously treated patients with stage IV squamous cell lung cancer: An immune biomarker analysis of phase III SWOG LungMAP S1400I trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1974.

Background: Lung squamous cell carcinoma (SCC) is the second most common type of non-small cell lung cancer. Immunotherapy is a promising treatment for SCC. However, only a small proportion of unselected SCC patients are able to achieve durable clinical benefit. We leveraged the precious specimens from S1400I trial and sought to explore whether the levels and spatial distributions of tumor-associated immune cells (TAICs) in screening samples are associated with PFS, and OS. Methods: We utilized paraffin tumor tissue provided by the SWOG bank from screening on LungMAP. 82/252 eligible SCC sample from patients treated with nivolumab plus ipilimumab (nivo+ipi; n = 35) or with nivolumab alone (nivo; n = 47) were studied. Image analysis tissue immunoprofiling was conducted using 9 markers in 2 multiplex immunofluorescence panels against cytokeratin, CD3, CD8, granzyme B, CD45RO, and FOXP3, PD1, PD-L1, and CD68. Densities of cells phenotypes (cells/mm2) were assessed and dichotomized as being high (> median) or low (≤ median) in tumor, stroma, and total compartments. Distances from malignant cells (MCs) to cell populations were measured and dichotomized as close from MCs (≤ median) and faraway from MCs (> median) and associated with clinical variables. Clinicopathologic features and data on PFS, and OS were retrieved from the CIDC portal as provided by the LungMap team. Non-parametric tests where utilized to assessment associations of cell phenotypes versus continue or categorical variables and log-rank test for survival analysis. Results: Univariate analysis showed that higher densities of memory T cells in total compartment (HR:0.63, CI:0.40-1.00, P=0.041), antigen-experienced T cells in the stroma (HR:0.60, CI:0.37-0.96, P=0.024) and total compartment (HR:0.60, CI:0.38-0.95, P=0.023) and activated cytotoxic T cells in the tumor compartment (HR:0.55, CI:0.35-0.87, P=0.011) were associated with significative better PFS. In the nivo+ipi arm, higher ratios of cytotoxic T cells to regulatory T cells in the stroma were associated with better PFS. The spatial analysis of these TAICs showed that the presence of activated cytotoxic T cells close to the MCs (median, ≤19.27 µm) was associated with better PFS (P=0.037). Conclusions: Our findings suggest that patients who have a detectable immunosuppressive tumor axis (PD-L1/PD1) with adequate activated cytotoxic T cells close to the tumor cells are the ideal patients for immune therapy to be targetable with these types of treatments. Acknowledgments: Scientific and financial support for: U10CA180888, U10CA180819U24CA224285, U24CA224316, PACT, PPP and FNIH. Citation Format: Edwin Roger Parra, Jiexin Zhang, Mary Redman, Rossana Lazcano, Piubelli Mario, Caddie Laberiano Fernandez, Renganayaki K. Krishna, Shanyu Zhang, Hong Chen, Ganiraju Manyam, Radim Moravec, Ethan Cerami, James Lindsay, Joyce Yu, Roshni Biswas, Stephen Van Nostrand, Dzifa Y. Duose, Jianjun Zhang, Roy Herbst, Gheath Al-Atrash, Kasthuri Kannan, Ignacio I. Wistuba, Scott Gettinger, Lyudmila Bazhenova, Jack Lee, Jianhua Zhang, Cara Haymaker. Infiltration and spatial distribution of immune cells are associated clinical benefit from Nivolumab and Ipilimumab for previously treated patients with stage IV squamous cell lung cancer: an immune biomarker analysis of Phase III SWOG LungMAP S1400I trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2580.

Clonal hematopoiesis (CH) is associated with older age and an increased risk of myeloid malignancies and cardiovascular complications. We analyzed donor DNA samples in patients with AML/MDS who underwent first allogeneic stem cell transplant (SCT) to investigate the association between donor CH and transplant outcomes. We performed targeted deep sequencing of 300 genes on donor blood samples and identified CH with the minimum variant allele frequency of 2%. Among 363 donors, 65 (18%) had CH. The most frequently mutated genes were DNMT3A (31 of 65; 48%), TET2 (16 of 65; 25%), PPM1D (5 of 65, 8%), and ASXL1 (7 of 65; 11%). Transplant outcomes: time to neutrophil and platelet recovery, relapse incidence, transplant-related mortality and progression-free survival, were comparable by donor CH. However, risk of grade II-IV and III-IV acute graft versus host disease (aGvHD) at 6 months after transplant was higher with donor CH vs. without donor CH (hazard ratio (HR) = 2.4, 95% Confidence Interval (CI) = 1.6-3.6, p 0.001 and HR = 3.8, 95% CI = 1.6-8.9, p = 0.003). In this homogenous population of AML/MDS patients, donor CH was associated with increased risk of grade II-IV and III-IV aGvHD. Further studies to investigate the mechanisms of increased aGvHD and therapeutic interventions to improve aGvHD in the context of donor CH are warranted.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with poor outcomes with conventional therapy. Nearly 100% of BPDCNs overexpress interleukin 3 receptor subunit alpha (CD123). Given that CD123 is differentially expressed on the surface of BPDCN cells, it has emerged as an attractive therapeutic target. UCART123 is an investigational product consisting of allogeneic T cells expressing an anti-CD123 chimeric antigen receptor (CAR), edited with TALEN® nucleases. In this study, we examine the antitumor activity of UCART123 in preclinical models of BPDCN. We report that UCART123 have selective antitumor activity against CD123-positive primary BPDCN samples (while sparing normal hematopoietic progenitor cells) in the in vitro cytotoxicity and T cell degranulation assays; supported by the increased secretion of IFNγ by UCART123 cells when cultured in the presence of BPDCN cells. UCART123 eradicate BPDCN and result in long-term disease-free survival in a subset of primary patient-derived BPDCN xenograft mouse models. One potential challenge of CD123 targeting therapies is the loss of CD123 antigen through diverse genetic mechanisms, an event observed in one of three BPDCN PDX studied. In summary, these results provide a preclinical proof-of-principle that allogeneic UCART123 cells have potent anti-BPDCN activity.

A6 is an eight amino acid peptide derived from the non-receptor binding region of urokinase plasminogen activator (uPA), which interferes with the uPA/uPA receptor system. A6 has been synthesized as a potential anti-angiogenic, anti-cancer agent. The current study has investigated the potential therapeutic activity of A6 in the Lewis lung carcinoma (3LL) model of pulmonary metastasis. A6 was found to have direct anti-tumor activity against established 3LL pulmonary metastases at a low tumor burden (10-20 colonies per lung) and was therapeutic in combination with cyclophosphamide at high tumor burdens (100 colonies per lung). Mechanistic studies have revealed that A6 directly inhibits the invasion of 3LL cells through a Matrigel model basement membrane by 40-45%. Moreover, treatment with either A6 or doxorubicin resulted in thicker tubes in endothelial tube formation studies. Our results suggest that A6, by virtue of its anti-invasive and anti-angiogenic properties, might work additively or synergistically with chemotherapeutic agents and thereby contribute to enhanced therapy of established 3LL cancer metastases.

Graft-versus-host disease (GVHD) prophylaxis with post-transplantation cyclophosphamide (CY) after ablative HLA-matched bone marrow (BM) transplantation has been reported to have comparable rates of acute GVHD with an apparent reduction in chronic GVHD and infections when compared to historical prophylaxis with a calcineurin-inhibitor (CNI) and methotrexate (MTX). We conducted a phase II trial of post-transplantation CY (post-CY) after reduced-intensity conditioning (RIC) using intravenous busulfan (area under the curve of 4000 micromolar minute), fludarabine (40 mg/m2) for 4 days, and CY 50 mg/kg on days +3 and +4 after BM or peripheral blood (PB) transplantations from matched related (MRD) or unrelated donors (MUD). MUD recipients received antithymocyte globulin (ATG); however, a later amendment removed ATG. Forty-nine patients were treated (acute myeloid leukemia/myelodysplastic syndrome, 82%). Median age was 62 years (range, 39 to 72). Fifteen patients received an MRD (9 PB/6 BM); 34 had a MUD (2 PB/32 BM). The cumulative incidence of grade II to IV acute GVHD, III to IV acute GVHD, and chronic GVHD was 58%, 22%, and 18%, respectively. A matched cohort analysis compared outcomes to tacrolimus/methotrexate GVHD prophylaxis and indicated higher rates of acute GVHD grade II to IV (46% versus 19%; hazard ratio [HR], 2.8; P = .02) and treatment-related mortality (HR, 3.3; P = .035) and worse overall survival (HR, 1.9; P = .04) with post-CY. The incidence of chronic GVHD and CMV reactivation did not differ. This study suggests that post-CY should not be used as sole GVHD prophylaxis after a RIC transplantation from HLA-matched donors.