A global study for acute myeloid leukemia with RARG rearrangement.

Acute myeloid leukemia (AML) with retinoic acid receptor γ (RARG) rearrangement has clinical, morphologic, and immunophenotypic features similar to classic acute promyelocytic leukemia. However, AML with RARG rearrangement is insensitive to alltrans retinoic acid (ATRA) and arsenic trioxide (ATO) and carries a poor prognosis. We initiated a global cooperative study to define the clinicopathological features, genomic and transcriptomic landscape, and outcomes of AML with RARG rearrangements collected from 29 study groups/institutions worldwide. Thirty-four patients with AML with RARG rearrangements were identified. Bleeding or ecchymosis was present in 18 (54.5%) patients. Morphology diagnosed as M3 and M3v accounted for 73.5% and 26.5% of the cases, respectively. Immunophenotyping showed the following characteristics: positive for CD33, CD13, and MPO but negative for CD38, CD11b, CD34, and HLA-DR. Cytogenetics showed normal karyotype in 38% and t(11;12) in 26% of patients. The partner genes of RARG were diverse and included CPSF6, NUP98, HNRNPc, HNRNPm, PML, and NPM1. WT1- and NRAS/KRAS-mutations were common comutations. None of the 34 patients responded to ATRA and/or ATO. Death within 45 days from diagnosis occurred in 10 patients (∼29%). At the last follow-up, 23 patients had died, and the estimated 2-year cumulative incidence of relapse, event-free survival, and overall survival were 68.7%, 26.7%, and 33.5%, respectively. Unsupervised hierarchical clustering using RNA sequencing data from 201 patients with AML showed that 81.8% of the RARG fusion samples clustered together, suggesting a new molecular subtype. RARG rearrangement is a novel entity of AML that confers a poor prognosis. This study is registered with the Chinese Clinical Trial Registry (ChiCTR2200055810).

Extracorporeal photopheresis for the treatment of chronic graft versus host disease.

OBJECTIVES: Chronic graft versus host disease (chronic GVHD) still remains the leading cause of late morbidity and mortality for allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients. In this retrospective study, 53 consecutive allo-HSCT patients with chronic GVHD refractory to corticosteroids were treated with extracorporeal photopheresis (ECP). METHODS: This study was performed as a retrospective single-center study. Medical records of a total of 59 patients treated with ECP for chronic GVHD were reviewed. RESULTS: Best organ responses to ECP were observed in skin, mouth mucosa, eyes and liver. Overall response rate (ORR) to ECP was 81.2% (CR 17% and PR 64.2%). Overall survival (OS) was 84.9% and 36.7%, at 1 and 3 years, respectively. Female sex appears to have an advantage on ORR. Patients achieving ORR were able to maintain their responses with a prolonged continuation of treatments for +6 and +12 months indicating the benefits of longer ECP treatment. DISCUSSION: We found that patients with chronic GVHD who were treated with ECP for 12 months or longer had a higher response rate. Our findings in line with the data reported previously suggest that patients responding to ECP should continue longer therapy schedules to achieve a better and sustained response. In our cohort, long-term ECP therapy was safe and well-tolerated with no significant adverse effects. Best responses were observed in the patients with skin, eye, liver and oral involvement. The ECP procedure offers the advantage relative to the problems with typical immunosuppressive agents. The female sex appeared to have an advantage based on the cumulative probability of the OR after ECP for chronic GVHD.

Alternative polyadenylation dysregulation contributes to the differentiation block of acute myeloid leukemia.

Posttranscriptional regulation has emerged as a driver for leukemia development and an avenue for therapeutic targeting. Among posttranscriptional processes, alternative polyadenylation (APA) is globally dysregulated across cancer types. However, limited studies have focused on the prevalence and role of APA in myeloid leukemia. Furthermore, it is poorly understood how altered poly(A) site usage of individual genes contributes to malignancy or whether targeting global APA patterns might alter oncogenic potential. In this study, we examined global APA dysregulation in patients with acute myeloid leukemia (AML) by performing 3' region extraction and deep sequencing (3'READS) on a subset of AML patient samples along with healthy hematopoietic stem and progenitor cells (HSPCs) and by analyzing publicly available data from a broad AML patient cohort. We show that patient cells exhibit global 3' untranslated region (UTR) shortening and coding sequence lengthening due to differences in poly(A) site (PAS) usage. Among APA regulators, expression of FIP1L1, one of the core cleavage and polyadenylation factors, correlated with the degree of APA dysregulation in our 3'READS data set. Targeting global APA by FIP1L1 knockdown reversed the global trends seen in patients. Importantly, FIP1L1 knockdown induced differentiation of t(8;21) cells by promoting 3'UTR lengthening and downregulation of the fusion oncoprotein AML1-ETO. In non-t(8;21) cells, FIP1L1 knockdown also promoted differentiation by attenuating mechanistic target of rapamycin complex 1 (mTORC1) signaling and reducing MYC protein levels. Our study provides mechanistic insights into the role of APA in AML pathogenesis and indicates that targeting global APA patterns can overcome the differentiation block in patients with AML.

Assessing CAR T-Cell Therapy Response Using Genome-Wide Sequencing of Cell-Free DNA in Patients With B-Cell Lymphomas.

Methods that enable monitoring of therapeutic efficacy of autologous chimeric antigen receptor (CAR) T-cell therapy will be clinically useful. The aim of this study is to demonstrate the feasibility of blood-derived cell-free DNA (cfDNA) to predict CAR T-cell therapy response in patients with refractory B-cell lymphomas. Whole blood was collected before and throughout CAR T-cell therapy until day 154. Low-coverage (∼0.4×), genome-wide cfDNA sequencing, similar to that established for noninvasive prenatal testing, was performed. The genomic instability number (GIN) was used to quantify plasma copy number alteration level. Twelve patients were enrolled. Seven (58%) patients achieved a complete response (CR); 2 (25%), a partial response. Median progression-free survival was 99 days; median overall survival was not reached (median follow-up, 247 days). Altogether, 127 blood samples were analyzed (median, 10 samples/patient [range 8-13]). All 5 patients who remained in CR at the time of last measurement had GIN <170 (threshold). Two patients who attained CR, but later relapsed, and all but one patient who had best response other than CR had last GIN measurement of >170. In 5 of 6 patients with relapsed or progressive disease, increasing GIN was observed before the diagnosis by imaging. The abundance of CAR T-cell construct (absolute number of construct copies relative to the number of human genome equivalents) also showed a trend to correlate with outcome (day 10, P = .052). These data describe a proof-of-concept for the use of multiple liquid biopsy technologies to monitor therapeutic response in B-cell lymphoma patients receiving CAR T-cell therapy.

MicroRNA let-7b downregulates AML1-ETO oncogene expression in t(8;21) AML by targeting its 3'UTR.

BACKGROUND: Acute myeloid leukemia (AML) with the t(8;21)(q22;q22) chromosomal translocation is among the most common subtypes of AML and produces the AML1-ETO (RUNX1-ETO, RUNX1-RUNX1T1) oncogenic fusion gene. AML1-ETO functions as an aberrant transcription factor which plays a key role in blocking normal hematopoiesis. Thus, the expression of AML1-ETO is critical to t(8;21) AML leukemogenesis and maintenance. Post-transcriptional regulation of gene expression is often mediated through interactions between trans-factors and cis-elements within transcript 3'-untranslated regions (UTR). AML1-ETO uses the 3'UTR of the ETO gene, which is not normally expressed in hematopoietic cells. Therefore, the mechanisms regulating AML1-ETO expression via the 3'UTR are attractive therapeutic targets. METHODS: We used RNA-sequencing of t(8;21) patients and cell lines to examine the 3'UTR isoforms used by AML1-ETO transcripts. Using luciferase assay approaches, we test the relative contribution of 3'UTR cis elements to AML1-ETO expression. We further use let-7b microRNA mimics and anti-let-7b sponges for functional studies of t(8;21) AML cell lines. RESULTS: In this study, we examine the regulation of AML1-ETO via the 3'UTR. We demonstrate that AML1-ETO transcripts primarily use a 3.7 kb isoform of the ETO 3'UTR in both t(8;21) patients and cell lines. We identify a negative regulatory element within the AML1-ETO 3'UTR. We further demonstrate that the let-7b microRNA directly represses AML1-ETO through this site. Finally, we find that let-7b inhibits the proliferation of t(8;21) AML cell lines, rescues expression of AML1-ETO target genes, and promotes differentiation. CONCLUSIONS: AML1-ETO is post-transcriptionally regulated by let-7b, which contributes to the leukemic phenotype of t(8;21) AML and may be important for t(8;21) leukemogenesis and maintenance.

In vitro induction of neoantigen-specific T cells in myelodysplastic syndrome, a disease with low mutational burden.

Therapies that utilize immune checkpoint inhibition work by leveraging mutation-derived neoantigens and have shown greater clinical efficacy in tumors with higher mutational burden. Whether tumors with a low mutational burden are susceptible to neoantigen-targeted therapy has not been fully addressed. To examine the feasibility of neoantigen-specific adoptive T-cell therapy, the authors studied the T-cell response against somatic variants in five patients with myelodysplastic syndrome (MDS), a malignancy with a very low tumor mutational burden. DNA and RNA from tumor (CD34+) and normal (CD3+) cells isolated from the patients' blood were sequenced to predict patient-specific MDS neopeptides. Neopeptides representing the somatic variants were used to induce and expand autologous T cells ex vivo, and these were systematically tested in killing assays to determine the proportion of neopeptides yielding neoantigen-specific T cells. The authors identified a total of 32 somatic variants (four to eight per patient) and found that 21 (66%) induced a peptide-specific T-cell response and 19 (59%) induced a T-cell response capable of killing autologous tumor cells. Of the 32 somatic variants, 11 (34%) induced a CD4+ response and 11 (34%) induced a CD8+ response that killed the tumor. These results indicate that in vitro induction of neoantigen-specific T cells is feasible for tumors with very low mutational burden and that this approach warrants investigation as a therapeutic option for such patients.

Gemtuzumab ozogamicin for the treatment of acute myeloid leukemia in adults.

INTRODUCTION: Treatment of acute myeloid leukemia (AML) has changed dramatically in the past ten years with the approval of targeted agents, the first of which was the anti-CD33 antibody-drug conjugate gemtuzumab ozogamicin (GO). Despite withdrawal from the market after accelerated approval, GO was reapproved and now has a well-established role in treating select AML patients. CD33 has proven to be an important target for drug development in AML as evidenced by the improvement in survival with GO treatment. AREAS COVERED: The review summarizes the development of GO, its mechanism of action, initial studies and approval, withdrawal from the market, and subsequent reapproval after the results of several large randomized studies became available. We also provide an overview of its current role in the treatment landscape of AML. EXPERT OPINION: Multiple phase 3 trials with GO have established a significant benefit with GO in induction therapy for favorable risk AML. Additional studies support the use of GO in relapsed/refractory AML and APL. Despite the withdrawal of GO from the market after initial approval, GO has proven to improve survival of select AML patients when added to induction chemotherapy and in relapsed disease.

A multicenter phase 1 study of nivolumab for relapsed hematologic malignancies after allogeneic transplantation.

Programmed cell death-1 (PD-1)/programmed death ligand-1 blockade may potentially augment graft-vs-tumor effects following allogeneic hematopoietic cell transplantation (alloHCT), but retrospective studies of anti-PD-1 therapy reported substantial toxicity from graft-versus-host-disease (GVHD). Here, we report the results of a prospective clinical trial of PD-1 blockade for relapsed hematologic malignancies (HMs) after alloHCT (NCT01822509). The primary objective in this phase 1 multicenter, investigator-initiated study was to determine maximum tolerated dose and safety. Secondary objectives were to assess efficacy and immunologic activity. Patients with relapsed HMs following alloHCT were eligible. Nivolumab was administered every 2 weeks until progression or unacceptable toxicity, starting with a 1-mg/kg cohort, with planned deescalation based on toxicity to a 0.5-mg/kg cohort. Twenty-eight patients were treated (n = 19 myeloid, n = 9 lymphoid). Median age was 57 years (range 27-76), and median time from alloHCT to enrollment was 21 months (range 5.6-108.5). Two of 6 patients treated at 1 mg/kg experienced dose-limiting toxicity (DLT) from immune-related adverse events (irAEs). Twenty-two patients were treated at 0.5 mg/kg, and 4 DLTs occurred, including 2 irAEs and 2 with fatal GVHD. The overall response rate in efficacy-evaluable patients was 32% (8/25). With a median follow-up of 11 months, the 1-year progression-free survival and overall survival were 23% and 56%, respectively. In this first prospective clinical trial of an anti-PD-1 antibody for post-alloHCT relapse, GVHD and irAEs occurred, requiring dose deescalation, with only modest antitumor activity. Further studies of anti-PD-1 therapy post-alloHCT may require specific toxicity mitigation strategies. This trial was registered at www.clinicaltrials.gov as #NCT01822509.

MHC-I genotype and tumor mutational burden predict response to immunotherapy.

BACKGROUND: Immune checkpoint blockade (ICB) with antibodies inhibiting cytotoxic T lymphocyte-associated protein-4 (CTLA-4) and programmed cell death protein-1 (PD-1) (or its ligand (PD-L1)) can stimulate immune responses against cancer and have revolutionized the treatment of tumors. The influence of host germline genetics and its interaction with tumor neoantigens remains poorly defined. We sought to determine the interaction between tumor mutational burden (TMB) and the ability of a patient's major histocompatibility complex class I (MHC-I) to efficiently present mutated driver neoantigens in predicting response ICB. METHODS: Comprehensive genomic profiling was performed on 83 patients with diverse cancers treated with ICB to determine TMB and human leukocyte antigen-I (HLA-I) genotype. The ability of a patient's MHC-I to efficiently present mutated driver neoantigens (defined by the Patient Harmonic-mean Best Rank (PHBR) score (with lower PHBR indicating more efficient presentation)) was calculated for each patient. RESULTS: The median progression-free survival (PFS) for PHBR score < 0.5 vs. ≥ 0.5 was 5.1 vs. 4.4 months (P = 0.04). Using a TMB cutoff of 10 mutations/mb, the stable disease > 6 months/partial response/complete response rate, median PFS, and median overall survival (OS) of TMB high/PHBR high vs. TMB high/PHBR low were 43% vs. 78% (P = 0.049), 5.8 vs. 26.8 months (P = 0.03), and 17.2 months vs. not reached (P = 0.23), respectively. These findings were confirmed in an independent validation cohort of 32 patients. CONCLUSIONS: Poor presentation of driver mutation neoantigens by MHC-I may explain why some tumors (even with a high TMB) do not respond to ICB.

Intensive Induction Therapy Compared With CHOP for Hepatosplenic T-cell Lymphoma.

INTRODUCTION: Hepatosplenic T-cell lymphoma (HSTCL) is a rare peripheral T-cell lymphoma that disproportionately affects individuals with a clinical history of immunosuppression. It carries a poor prognosis, and, owing to its rarity, there is no single or well-established treatment. PATIENTS AND METHODS: We conducted the largest-to-date individual-level meta-analysis based on literature searches to determine the best induction therapy for HSTCL. We compared response rates and survival among patients who received "non-CHOP-based" induction with regimens containing cytarabine, etoposide, and/or platinum-based treatment to those receiving treatment with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) or CHOP-like therapy. We also review additional regimens including alemtuzumab and pentostatin, and assessed the role of consolidation with hematopoietic stem-cell transplantation (HSCT). RESULTS: We identified 166 patients with HSTCL, 118 of whom had sufficient information on induction treatment and survival. Eighty-four patients received non-CHOP-based (N = 34) or CHOP/CHOP-like (N = 50) induction treatment. Non-CHOP-based induction was associated with a complete/partial response rate of 82% compared with 52% (P = .006) with CHOP/CHOP-like and increased median overall survival (P = .00014). Our data showed that maximum survival among patients with HSTCL was achieved with non-CHOP-based induction followed by consolidation with HSCT. CONCLUSIONS: Non-CHOP-based induction appears superior to CHOP/CHOP-like induction in both achieving complete/partial response and durable survival. Induction therapy of HSTCL should be intensified with non-CHOP-based regimens and followed by consolidation with HSCT in eligible patients.

Predicting Responses to Checkpoint Inhibitors in Lymphoma: Are We Up to the Standards of Solid Tumors?

Treatment of cancer has transformed with the introduction of checkpoint inhibitors. However, the majority of solid tumor patients do not respond to checkpoint blockade. In contrast, the response rate to programmed cell death 1 (PD-1) blockade in relapsed/refractory classical Hodgkin lymphoma (cHL) is 65% to 84% which is the highest among all cancers. Currently, checkpoint inhibitors are only approved for cHL and primary mediastinal B-cell lymphoma as the responses to single-agent checkpoint blockade in other hematologic malignancies is disappointingly low. Various established biomarkers such as programmed cell death 1 ligand 1 (PD-L1) protein surface expression, mismatch repair (MMR) status, and tumor mutational burden (TMB) are routinely used in clinical decision-making in solid tumors. In this review, we will explore these biomarkers in the context of hematologic malignancies. We review characteristic 9p24.1 structural alteration in cHL and primary mediastinal B-cell lymphoma (PMBCL) as a basis for response to PD-1 inhibition, as well as the role of antigen presentation pathways. We also explore the reported frequencies of MMR deficiency in various hematologic malignancies and investigate TMB as a predictive marker.

Higher Risks of Toxicity and Incomplete Recovery in 13- to 17-Year-Old Females after Marrow Donation: RDSafe Peds Results.

Although donation of bone marrow (BM) or peripheral blood stem cells (PBSCs) from children to family members undergoing allogeneic transplantation are well-established procedures, studies detailing levels of pain, symptoms, and long-term recovery are lacking. To address this lack, we prospectively enrolled 294 donors age <18 years at 25 pediatric transplantation centers in North America, assessing them predonation, peridonation, and at 1 month, 6 months, and 1 year postdonation. We noted that 71% of children reported pain and 59% reported other symptoms peridonation, with resolution to 14% and 12% at 1 month postdonation. Both older age (age 13 to 17 years versus younger) and female sex were associated with higher levels of pain peridonation, with the highest rates in older females (57% with grade 2-4 pain and 17% with grade 3-4 pain). Multivariate analyses showed a 4-fold increase in risk for older females compared with males age <13 years (P <.001). At 1 year, 11% of 13- to 17-year-old females reported grade 2-4 pain, compared with 3% of males age 13 to 17 years, 0% of females age <13 years, and 1% of males age <13 years (P = .01). Males and females age 13 to 17 years failed to return to predonation pain levels at 1 year 22% and 23% of the time, respectively, compared with 3% and 10% in males and females age <13 years (P = .002). Our data show that females age 13 to 17 years are at increased risk of grade 2-4 pain at 1 year and >20% of females and males age 13 to 17 years do not return to baseline pain levels by 1 year after BM donation. Studies aimed at decreasing symptoms and improving recovery in older children are warranted.

Related peripheral blood stem cell donors experience more severe symptoms and less complete recovery at one year compared to unrelated donors.

Unlike unrelated donor registries, transplant centers lack uniform approaches to related donor assessment and deferral. To test whether related donors are at increased risk for donation-related toxicities, we conducted a prospective observational trial of 11,942 related and unrelated donors aged 18-60 years. Bone marrow (BM) was collected at 37 transplant and 78 National Marrow Donor Program centers, and peripheral blood stem cells (PBSC) were collected at 42 transplant and 87 unrelated donor centers in North America. Possible presence of medical comorbidities was verified prior to donation, and standardized pain and toxicity measures were assessed pre-donation, peri-donation, and one year following. Multivariate analyses showed similar experiences for BM collection in related and unrelated donors; however, related stem cell donors had increased risk of moderate [odds ratios (ORs) 1.42; P<0.001] and severe (OR 8.91; P<0.001) pain and toxicities (OR 1.84; P<0.001) with collection. Related stem cell donors were at increased risk of persistent toxicities (OR 1.56; P=0.021) and non-recovery from pain (OR 1.42; P=0.001) at one year. Related donors with more significant comorbidities were at especially high risk for grade 2-4 pain (OR 3.43; P<0.001) and non-recovery from toxicities (OR 3.71; P<0.001) at one year. Related donors with more significant comorbidities were at especially high risk for grade 2-4 pain (OR 3.43; P<0.001) and non-recovery from toxicities (OR 3.71; P<0.001) at one year. Related donors reporting grade ≥2 pain had significant decreases in Health-Related Quality of Life (HR-QoL) scores at one month and one year post donation (P=0.004). In conclusion, related PBSC donors with comorbidities are at increased risk for pain, toxicity, and non-recovery at one year after donation. Risk profiles described in this study should be used for donor education, planning studies to improve the related donor experience, and decisions regarding donor deferral. Registered at clinicaltrials.gov identifier:00948636.

Effect of Aging and Predonation Comorbidities on the Related Peripheral Blood Stem Cell Donor Experience: Report from the Related Donor Safety Study.

The development of reduced-intensity approaches for allogeneic hematopoietic cell transplantation has resulted in growing numbers of older related donors (RDs) of peripheral blood stem cells (PBSCs). The effects of age on donation efficacy, toxicity, and long-term recovery in RDs are poorly understood. To address this we analyzed hematologic variables, pain, donation-related symptoms, and recovery in 1211 PBSC RDs aged 18 to 79 enrolled in the Related Donor Safety Study. RDs aged > 60 had a lower median CD34+ level before apheresis compared with younger RDs (age > 60, 59 × 106/L; age 41 to 60, 81 × 106/L; age 18 to 40, 121 × 106/L; P < .001). This resulted in older donors undergoing more apheresis procedures (49% versus 30% ≥ 2 collections, P < .001) and higher collection volumes (52% versus 32% > 24 L, P < .001), leading to high percentages of donors aged > 60 with postcollection thrombocytopenia <50 × 109/L (26% and 57% after 2 and 3days of collection, respectively). RDs aged 18 to 40 had a higher risk of grades 2 to 4 pain and symptoms pericollection, but donors over age 40 had more persistent pain at 1, 6, and 12 months (odds ratio [OR], 1.7; P = 0.02) and a higher rate of nonrecovery to predonation levels (OR, 1.7; P = .01). Donors reporting comorbidities increased significantly with age, and those with comorbidities that would have led to deferral by National Marrow Donor Program unrelated donor standards had an increased risk for persistent grades 2 to 4 pain (OR, 2.41; P < .001) and failure to recover to predonation baseline for other symptoms (OR, 2.34; P = .004). This information should be used in counseling RDs regarding risk and can assist in developing practice approaches aimed at improving the RD experience for high-risk individuals.

Improved accuracy of clinical HLA genotyping by next-generation DNA sequencing affects unrelated donor search results for hematopoietic stem cell transplantation.

Matching of human leukocyte antigen (HLA) genes is critically important in hematopoietic stem cell transplantation (HSCT). HLA genes are highly polymorphic and HLA matching has historically been limited by technologies that are unable to unambiguously determine HLA genotypes. Next generation DNA sequencing (NGS) overcomes these limitations by enabling near full-gene sequences with phase determination for heterozygous alleles. Here we examine the efficacy and utility of HLA-NGS in the clinical setting. In a 54-sample validation study and 955 patient samples subsequently tested using HLA-NGS, we observed significant improvement in the ability to unambiguously identify HLA genotypes in both the validation (97.3%) and clinical (97.4%) sample cohorts compared to previous standard-of care HLA genotyping methods. We modeled the clinical impact of this improved diagnostic ability by comparing National Marrow Donor Program (NMDP) search results for 56 patients using HLA-NGS genotypes and simulated standard-of-care HLA genotypes. Surprisingly, we observed significant differences in 7.1% of NMDP searches, with improved unambiguous HLA genotyping correlating with improved prediction of finding well-matched and partially-matched unrelated HSCT donors. These data demonstrate that HLA-NGS can provide highly accurate and unambiguous HLA genotyping that facilitates donor selection for allogeneic HSCT.

A Phase I/II Trial of the Combination of Azacitidine and Gemtuzumab Ozogamicin for Treatment of Relapsed Acute Myeloid Leukemia.

INTRODUCTION: Treatment with hypomethylating agent therapy might enhance anti-CD33 monoclonal antibody-mediated cytotoxicity against acute myeloid leukemia (AML) blasts through epigenetic effects on Syk and SHP-1 expression. PATIENTS AND METHODS: In the present phase I/II study, we treated patients with relapsed or refractory AML with azacitidine, followed by 2 doses of gemtuzumab ozogamicin (GO) at 6 mg/m2, the Food and Drug Administration-approved dose and schedule at study initiation. We sought to determine the maximum tolerated dose and clinical activity of this combination therapy. Secondarily, we aimed to determine whether baseline Syk and SHP-1 expression can be used as predictive biomarkers of treatment response. RESULTS: The established maximum tolerated dose was azacitidine 75 mg/m2 daily for 6 consecutive days, followed by GO 6 mg/m2 on days 7 and 21. Of the 50 evaluable patients, 12 (24%) obtained complete remission (CR) or CR with incomplete peripheral blood recovery (CRp). No dose-limiting toxicities were observed in phase I, and no patient developed hepatic sinusoidal obstructive syndrome. Although no significant correlation was found between Syk and SHP-1 expression and the clinical response to combination therapy, in vitro studies repeatedly demonstrated that azacitidine-treated AML cells had an increased response to GO treatment. CONCLUSION: Our study found that the combination of GO with azacitidine is relatively well tolerated, with response rates similar to those with GO monotherapy at higher doses. Differences in the GO drug schedule, dose level, and frequency might explain the discrepant response rates between our study and others, suggesting that the optimal GO dose remains unclear, especially when combined with hypomethylating agent therapy.

Proinflammatory Dual Receptor T Cells in Chronic Graft-versus-Host Disease.

Defective post-transplantation thymopoiesis is associated with chronic graft-versus-host disease (GVHD), a multiorgan pathology affecting up to 80% of patients after allogeneic hematopoietic stem cell transplantation (HSCT). Previous work demonstrated that the subset of T cells expressing 2 T cell receptors (TCRs) is predisposed to alloreactivity, driving selective and disproportionate activity in acute GVHD in both mouse models and HSCT patients. Here we investigate a potential role for this pathogenic T cell subset in chronic GVHD (cGVHD). HSCT patients with cGVHD demonstrated increased numbers of dual TCR cells in circulation. These dual receptor cells had an activated phenotype, indicating an active role in cGVHD. Notably, single-cell RNA sequencing identified the increased dual TCR cells in cGVHD as predominantly expressing Tbet, indicative of a proinflammatory phenotype. These results identify dual TCR cells as specific mediators of pathogenic inflammation underlying cGVHD and highlight Tbet-driven T cell function as a potential pathway for potential therapeutic targeting.

Increased Foxp3+Helios+ Regulatory T Cells and Decreased Acute Graft-versus-Host Disease after Allogeneic Bone Marrow Transplantation in Patients Receiving Sirolimus and RGI-2001, an Activator of Invariant Natural Killer T Cells.

Regulatory T (Treg) cells play a central role in immune tolerance and prevention of aberrant immune responses. Several studies have suggested that the risk of graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (HCT) can be ameliorated by increasing Tregs. We have developed an approach of in vivo expansion of Tregs with RGI-2001, a novel liposomal formulation of a synthetic derivative of alpha-galactosylceramide, a naturally occurring ligand that binds to CD1 and activates and expands invariant natural killer cells. In preclinical studies, a single intravenous infusion of RGI-2001 expanded Treg and could ameliorate GVHD in a mouse model of allogeneic HCT. To explore the role of RGI-2001 in clinical HCT, we initiated a phase 2A clinical trial (n = 29), testing 2 different doses of RGI-2001 administered as a single infusion on day 0 of allogeneic HCT. RGI-2001 was well tolerated and without infusion reactions or cytokine release syndrome. A subset of patients (8 of 29, 28%) responded to RGI-2001 by inducing a markedly increased number of cells with a Treg phenotype. The Treg had a high Ki-67 index and were almost exclusively Helios+ and Foxp3+, indicating that their accumulation was due to expansion of natural Treg. Notably, the incidence of grade 2 to 4 GVHD in the 8 patients who responded to RGI-2001 was 12.5%, compared with 52.4% in the 21 patients who did not respond. No grade 3 or 4 GVHD was observed in the responder group, compared with a 9.5% incidence among nonresponders. Immunosuppression with sirolimus was also associated with a low incidence of GVHD, suggesting that RGI-2001 may have synergized with sirolimus to promote Treg expansion.