Dual targeting of glutamine and serine metabolism in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy characterized by disrupted blood cell production and function. Recent investigations have highlighted the potential of targeting glutamine metabolism as a promising therapeutic approach for AML. Asparaginases, enzymes that deplete circulating glutamine and asparagine, are approved for the treatment of acute lymphoblastic leukemia, but are also under investigation in AML, with promising results. We previously reported an elevation in plasma serine levels following treatment with Erwinia-derived asparaginase (also called crisantaspase). This led us to hypothesize that AML cells initiate the de novo serine biosynthesis pathway in response to crisantaspase treatment and that inhibiting this pathway in combination with crisantaspase would enhance AML cell death. Here we report that in AML cell lines, treatment with the clinically available crisantaspase, Rylaze, upregulates the serine biosynthesis enzymes phosphoglycerate dehydrogenase (PHGDH) and phosphoserine aminotransferase (PSAT1) through activation of the Amino Acid Response (AAR) pathway, a cellular stress response mechanism that regulates amino acid metabolism and protein synthesis under conditions of nutrient limitation. Inhibition of serine biosynthesis through CRISPR-Cas9-mediated knockout of PHGDH resulted in a ~250-fold reduction in the half-maximal inhibitory concentration (IC50) for Rylaze, indicating heightened sensitivity to crisantaspase therapy. Treatment of AML cells with a combination of Rylaze and a small molecule inhibitor of PHGDH (BI4916) revealed synergistic anti-proliferative effects in both cell lines and primary AML patient samples. Rylaze-BI4916 treatment in AML cell lines led to the inhibition of cap-dependent mRNA translation and protein synthesis, as well as a marked decrease in intracellular glutathione levels, a critical cellular antioxidant. Collectively, our results highlight the clinical potential of targeting serine biosynthesis in combination with crisantaspase as a novel therapeutic strategy for AML.

Long-Term Follow up of Blinatumomab in Older Patients with B-Cell Acute Lymphoblastic Leukemia.

Older adults who are diagnosed with acute lymphoblastic leukemia (ALL) and are treated with chemotherapy generally have poor outcomes. Blinatumomab is a CD19/CD3 bispecific T-cell engager that has been approved for the treatment of B-cell ALL in the relapsed/refractory setting or in patients with minimal residual disease (MRD) positivity. We previously reported on a small cohort of older adults with newly diagnosed Philadelphia chromosome negative B-cell ALL who were treated with blinatumomab monotherapy in the first line setting. This is a long-term follow up of those patients and their clinical courses. All five patients achieved complete remission (CR) after one cycle of blinatumomab, and three were MRD-negative. Two patients completed three cycles of blinatumomab, two patients completed four cycles of blinatumomab, and one patient completed 17 cycles of blinatumomab total. In the last four years, four of these patients had relapsed disease requiring additional therapy. Two patients are alive after 61 months and 57 months since their first cycle of blinatumomab. Two of the patients died at 10 months and one died at 20 months. Here we describe the long-term clinical courses of these patients.

Clinical outcomes of patients with acute myeloid leukemia and cardiovascular disease.

Incidence of both acute myeloid leukemia (AML) and cardiovascular disease (CVD) increases with age. We evaluated whether pre-existing CVD impacts clinical outcomes in AML. We retrospectively evaluated 291 consecutive adult AML patients treated at our institution, 2014-2020. Pretreatment comorbidities were identified by chart review. Outcomes included complete remission (CR) and CR with incomplete count recovery (CRi) rates, disease-free survival (DFS), overall survival (OS) and incidence of cardiovascular adverse events. CVD was present in 34% of patients at AML diagnosis. CVD patients had worse performance status (p=0.03) and more commonly had secondary AML (p=0.03) and received hypomethylating (HMA) agent-based therapy (72% vs 38%, p< 0.001). CVD (0.45 vs 0.71, p<0.001) and diabetes mellitus (HR= 0.24, 95% CI: 0.08 - 0.8, p= 0.01) were associated with lower probability of achieving CR/CRi. Accounting for age, performance status (PS), complex karyotype, secondary disease and treatment, CVD patients had shorter OS (HR=1.5, 95% CI: 1.1-2.2, p=0.002), with 1- and 3-year OS 44% vs 67% and 25% vs 40%, respectively, but there was no difference in cumulative incidence of relapse between patients with vs without CVD. Thus, CVD is an independent risk factor for lower response rate and shorter survival in AML patients.

Community-engaged basic science in an NCI-designated comprehensive cancer center: antioxidants and chemotherapeutic efficacy.

PURPOSE: While community engagement has been a longstanding aspect of cancer-relevant research in social and behavioral sciences, it is far less common in basic/translational/clinical research. With the National Cancer Institute's incorporation of Community Outreach and Engagement into the Cancer Center Support Grant guidelines, successful models are desirable. We report on a pilot study supported by the University of Maryland Greenebaum Comprehensive Cancer Center (UMGCCC), that used a community-engaged, data-driven process to inform a pre-clinical study of the impact of antioxidants on the efficacy of platinum-based chemotherapeutics. METHODS: We conducted a survey of UMGCCC catchment area residents (n = 120) to identify commonly used antioxidants. We then evaluated the effect of individually combining commonly used antioxidants from the survey (vitamin C, green tea, and melatonin) with platinum agents in models of non-small cell lung cancer (A549), colon adenocarcinoma (SW620) and head and neck squamous cell carcinoma (FaDu). RESULTS: In vitro, the anti-neoplastic activity of each chemotherapy was not potentiated by any of the antioxidants. Instead, when combined at fixed ratios, most antioxidant-chemotherapy combinations were antagonistic. In vivo, addition of antioxidants did not improve chemotherapeutic efficacy and in a FaDu-tumor bearing model, cisplatin-mediated tumor growth inhibition was significantly impeded by the addition of epigallocatechin gallate, the main antioxidant in green tea. CONCLUSION: These initial findings do not support addition of antioxidant supplementation to improve platinum-based chemotherapeutic efficacy. This study's approach can serve as a model of how to bring together the two seemingly discordant areas of basic research and community engagement.

Cytogenetics and molecular genetics of myelodysplastic neoplasms.

According to the 2022 World Health Organization (WHO) Classification (5th edition), the term myelodysplastic neoplasms (abbreviated MDS) has been introduced to replace myelodysplastic syndromes. MDS are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more of lineages, ineffective hematopoiesis, and an increased risk of progression to bone marrow failure or to acute myeloid leukemia (AML). Current NCCN guidelines and recent review articles have provided in depth discussion on the clinical diagnosis and management of MDS. This review will focus on discussion of the WHO and International Consensus Classification (ICC) updates on the role of cytogenetics and molecular genetics in the diagnosis and risk stratification of MDS.

Aspacytarabine for the treatment of patients with AML unfit for intensive chemotherapy: a phase 2 study.

High-dose cytarabine is associated with gastrointestinal and cerebellar toxicity, precluding its use for older or unfit patients with acute myeloid leukemia (AML). Aspacytarabine, an inactive prodrug of cytarabine, was evaluated as monotherapy in a phase 2b study of patients unfit for intensive chemotherapy (NCT03435848). Sixty-five patients with AML were treated with aspacytarabine 4.5 g/m2 per day (equimolar to 3 g/m2 per day cytarabine) for 6 doses per treatment. The median age was 75 years; 60.6% of patients had de novo AML, 28.8% had AML secondary to myelodysplastic syndrome, and 10.6% had therapy-related AML. Overall, 36.9% achieved complete remission (CR) with full count recovery. CR rates in patients with secondary AML, patients with prior treatment with hypomethylating agents, and patients with TP53 mutation were 26.7%, 25%, and 36%, respectively. Median overall survival was 9 months (range, 6-15.9) and was not reached among responders. Hematologic recovery was observed in all responding patients by day 26 without prolonged cytopenias. Adverse events typically precluding the use of high-dose cytarabine in older or unfit patients were not observed. These data suggest that aspacytarabine may be an effective regimen with a reduction in the attendant toxicities associated with high-dose cytarabine, an important consideration when treating AML and other hematologic disorders that use high-dose cytarabine. This trial was registered at www.clinicaltrials.gov as #NCT03435848.

Olanzapine within steroid-sparing antiemetic regimen to prevent chemotherapy-induced nausea and vomiting in patients with acute leukemia receiving multi-day intensive chemotherapy.

INTRODUCTION: Olanzapine use for chemotherapy-induced nausea and vomiting (CINV) in hematological malignancies, for multi-day chemotherapy, and with a steroid-sparing antiemetic strategy is poorly understood. This study investigated if olanzapine is associated with improved prevention of CINV when added to a steroid-sparing antiemetic regimen in patients with acute leukemia receiving intensive, moderately emetogenic, multi-day chemotherapy. METHODS: This was a single-center, retrospective cohort study in patients with acute leukemia. Patients who received olanzapine for CINV prevention were compared to those who did not. All patients received a 5-HT3 antagonist. Adult patients receiving moderately emetogenic, multi-day, intensive chemotherapy for acute leukemia were included. Patients were excluded if they received steroids greater than physiological doses during the study period. The primary endpoint was the complete response of CINV (no emesis or rescue antiemetic usage). RESULTS: This study included 58 patients, 12 patients received olanzapine and 46 patients were in the control group. Baseline demographics were similar. In the study population, 89.7% had acute myeloid leukemia, median age was 54 (interquartile range 42-63) years, 34.5% were female, 27.6% had prior CINV. Complete response of CINV was similar between groups, 4 (33.3%) and 15 (32.6%) patients in the olanzapine and control groups, respectively. Safety events were similar between groups. CONCLUSION: Patients with acute leukemia receiving multi-day intensive chemotherapy are at high risk for CINV. The limited data in this study suggests that olanzapine use within a steroid-sparing antiemetic regimen was well tolerated and associated with similar incidence and severity of CINV compared to the control group.

Impact of pegaspargase dose capping on incidence of pegaspargase-related adverse events in adults.

INTRODUCTION: Asparaginase derivatives are essential components of the treatment of acute lymphoblastic leukemia in adolescent and young adult patients. However, their associated toxicities limit wider use in older populations. This study seeks to determine if the practice of capping the pegaspargase dose at 3750 units reduces the risk of related adverse events in adults. METHODS: Adverse event data were retrospectively collected 28 days following each administration of pegaspargase in a single center. Doses were categorized as either capped (≤3750 units) (n = 57, 47.5%) or non-capped (>3750 units) (n = 63, 52.5%). The primary endpoint of this study was the composite incidence of serious pegaspargase-related adverse events, defined as grade 3 or higher. RESULTS: Of the 120 doses administered, 47 (39.2%) were administered to patients > 39 years. For the primary endpoint, 26 doses (45.6%) in the dose capped group versus 22 doses (34.9%) in the non-dose capped group were associated with serious pegaspargase-related adverse events (p = 0.23). Isolated laboratory abnormalities accounted for all hepatotoxicity and pancreatic toxicity events, while venous thromboembolism and bleeding occurred after 8.3% and 13.3% of doses, respectively. Multivariate analysis of the primary outcome to adjust for differences in baseline characteristics found no difference between groups (OR 2.56 (0.84, 7.77, p = 0.098)). CONCLUSIONS: The incidence of serious clinical toxicities was low in this study, particularly pegaspargase-related venous thromboembolism. This suggests that the practice of capping pegaspargase doses at 3750 units, coupled with vigilant monitoring and prophylaxis for pegaspargase-related adverse events, can allow for the inclusion of this drug in the treatment of older individuals.

Hypertension, smoking, and preexistence of multiple cardiac risk factors correlate with carfilzomib-induced cardiovascular adverse events in a racially diverse population.

Background: Use of the proteasome inhibitor carfilzomib has become a standard of care in patients with relapsed/refractory multiple myeloma. An association between carfilzomib and cardiovascular adverse events has been well documented, but this had not been investigated in a racially diverse population. Black patients in particular are underrepresented in the reported outcomes of treatment with carfilzomib. Objective: The purpose of this study was to identify risk factors for carfilzomib-associated cardiovascular events in a diverse, single-center population. Methods: We conducted a retrospective review of 161 patients with multiple myeloma treated with carfilzomib between 2011 and 2020 at the University of Maryland Medical Center. Over half (86) were Black patients, with the remainder (75) being White patients. We did a multivariate analysis to determine risk factors for developing cardiovascular events during treatment with carfilzomib. Results: There was no statistically significant association with cardiotoxicity and race, gender, or age at first dose of carfilzomib. In multivariable analysis, patients with history of hypertension had a higher risk of cardiotoxicity [adjusted odds ratio (OR): 2.5; 95% CI: 1.1-5.9; P = 0.03] as did those with a history of smoking [OR: 2.8; 95% CI: 1.3-6.4; P = 0.01]. Conclusions: Here we report the largest cohort of Black patients treated with carfilzomib as yet reported. The results of this single center retrospective study show history of hypertension and smoking are associated with carfilzomib associated cardiotoxicity in a diverse patient population. There is a need for well-designed prospective studies enrolling a diverse population to investigate potential interventions to prevent carfilzomib-associated cardiotoxicity.

Mesothelioma cancer cells are glutamine addicted and glutamine restriction reduces YAP1 signaling to attenuate tumor formation.

Glutamine addiction is an important phenotype displayed in some types of cancer. In these cells, glutamine depletion results in a marked reduction in the aggressive cancer phenotype. Mesothelioma is an extremely aggressive disease that lacks effective therapy. In this study, we show that mesothelioma tumors are glutamine addicted suggesting that glutamine depletion may be a potential therapeutic strategy. We show that glutamine restriction, by removing glutamine from the medium or treatment with inhibitors that attenuate glutamine uptake (V-9302) or conversion to glutamate (CB-839), markedly reduces mesothelioma cell proliferation, spheroid formation, invasion, and migration. Inhibition of the SLC1A5 glutamine importer, by knockout or treatment with V-9302, an SLC1A5 inhibitor, also markedly reduces mesothelioma cell tumor growth. A relationship between glutamine utilization and YAP1/TEAD signaling has been demonstrated in other tumor types, and the YAP1/TEAD signaling cascade is active in mesothelioma cells and drives cell survival and proliferation. We therefore assessed the impact of glutamine depletion on YAP1/TEAD signaling. We show that glutamine restriction, SLC1A5 knockdown/knockout, or treatment with V-9302 or CB-839, reduces YAP1 level, YAP1/TEAD-dependent transcription, and YAP1/TEAD target protein (e.g., CTGF, cyclin D1, COL1A2, COL3A1, etc.) levels. These changes are observed in both cells and tumors. These findings indicate that mesothelioma is a glutamine addicted cancer, show that glutamine depletion attenuates YAP1/TEAD signaling and tumor growth, and suggest that glutamine restriction may be useful as a mesothelioma treatment strategy.

Erwinia asparaginase (crisantaspase) increases plasma levels of serine and glycine.

The impact of asparaginases on plasma asparagine and glutamine is well established. However, the effect of asparaginases, particularly those derived from Erwinia chrysanthemi (also called crisantaspase), on circulating levels of other amino acids is unknown. We examined comprehensive plasma amino acid panel measurements in healthy immunodeficient/immunocompetent mice as well as in preclinical mouse models of acute myeloid leukemia (AML) and pancreatic ductal adenocarcinoma (PDAC) using long-acting crisantaspase, and in an AML clinical study (NCT02283190) using short-acting crisantaspase. In addition to the expected decrease of plasma glutamine and asparagine, we observed a significant increase in plasma serine and glycine post-crisantaspase. In PDAC tumors, crisantaspase treatment significantly increased expression of serine biosynthesis enzymes. We then systematically reviewed clinical studies using asparaginase products to determine the extent of plasma amino acid reporting and found that only plasma levels of glutamine/glutamate and asparagine/aspartate were reported, without measuring other amino acid changes post-asparaginase. To the best of our knowledge, we are the first to report comprehensive plasma amino acid changes in mice and humans treated with asparaginase. As dysregulated serine metabolism has been implicated in tumor development, our findings offer insights into how leukemia/cancer cells may potentially overcome glutamine/asparagine restriction, which can be used to design future synergistic therapeutic approaches.

Therapy-related B-lymphoblastic leukemia after multiple myeloma.

New therapies for multiple myeloma have improved outcomes, but are associated with therapy-related hematologic malignancies. We report eight patients with therapy-related B-lymphoblastic leukemias (t-B-ALL) in the setting of therapy for multiple myeloma, which included lenalidomide maintenance. A subset of patients had pancytopenia and low-level marrow involvement by acute leukemia, an unusual finding in de novo B-ALL. One patient died of chemotherapy complications; the other seven responded. No patient died of B-ALL (median follow up of 1.0 years). Our series suggests that t-B-ALL is clonally unrelated to myeloma, presents with diverse cytogenetic abnormalities, and responds well to B-ALL therapy.

Safety, Outcomes, and T-Cell Characteristics in Patients with Relapsed or Refractory MDS or CMML Treated with Atezolizumab in Combination with Guadecitabine.

PURPOSE: We hypothesized that resistance to hypomethylating agents (HMA) among patients with myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML) would be overcome by combining a programmed death-ligand 1 antibody with an HMA. PATIENTS AND METHODS: We conducted a Phase I/II, multicenter clinical trial for patients with MDS not achieving an International Working Group response after at least 4 cycles of an HMA ("refractory") or progressing after a response ("relapsed") with 3+ or higher risk MDS by the revised International Prognostic Scoring System (IPSS-R) and CMML-1 or -2. Phase I consisted of a 3+3 dose-escalation design beginning with guadecitabine at 30 mg/m2 and escalating to 60 mg/m2 Days 1 to 5 with fixed-dose atezolizumab: 840 mg intravenously Days 8 and 22 of a 28-day cycle. Primary endpoints were safety and tolerability; secondary endpoints were overall response rate (ORR) and survival. RESULTS: Thirty-three patients, median age 73 (range 54-85), were treated. Thirty patients had MDS and 3 had CMML, with 30% relapsed and 70% refractory. No dose-limiting toxicities were observed in Phase I. There were 3 (9%) deaths in ≤ 30 days. Five patients (16%) came off study for drug-related toxicity. Immune-related adverse events (IRAE) occurred in 12 (36%) patients (4 grade 3, 3 grade 2, and 5 grade1). ORR was 33% [95% confidence interval (CI), 19%-52%] with 2 complete remission (CR), 3 hematologic improvement, 5 marrow CR, and 1 partial remission. Median overall survival was 15.1 (95% CI, 8.5-25.3) months. CONCLUSIONS: Guadecitabine with atezolizumab has modest efficacy with manageable IRAEs and typical cytopenia-related safety concerns for patients with relapsed or refractory MDS and CMML.

Impact of FLT3-ITD Insertion Length on Outcomes in Acute Myeloid Leukemia: A Propensity Score-Adjusted Cohort Study.

The prognostic significance of the length of internal tandem duplication (ITD) insertions in mutant FLT3 genes in acute myeloid leukemia (AML) is controversial. We conducted a retrospective study to evaluate the correlation between the ITD base-pair (bp) insertion length and clinical outcomes. The mutational status of the FLT3 gene was evaluated in 402 of 467 consecutive AML patients treated at the University of Maryland Greenebaum Comprehensive Cancer Center between 2013 and 2020; 77 had FLT3-ITD mutations. Patients were divided into three cohorts based on bp insertion length (<30 (0−33rd percentile), 30−53 (34th−66th percentile),and >53 (>66th percentile)). The median overall survival (OS) of patients was 16.5 months (confidence interval (CI) 7.3-NA), 18.5 months (CI 7.3-NA), and 21.9 months (CI 19.1-NA) (p = 0.03) for the <30, 30−53, and >53 bp insertion length cohorts, respectively. The adjusted median event-free survival (EFS) for the ITD insertion lengths >30, 30−53, and >53 bp was 11.1 months (CI 2.8−16.5), 5.2 months (CI 2.9−12.6), and 9.1 months (CI 5.4-NA) (p = 0.5), respectively. Complete remission (CR) rates were 64% (<30 inserted bp), 55% (30−53 inserted bp), and 79% (>53 inserted bp) (p = 0.23). For patients treated with gilteritinib and midostaurin, the unadjusted median OS was not statistically significantly different between cohorts.

Outcomes of Newly Diagnosed Acute Myeloid Leukemia Patients Treated With Hypomethylating Agents With or Without Venetoclax: A Propensity Score-Adjusted Cohort Study.

There is a deficiency of real-world data on the impact of combining venetoclax (VEN) with hypomethylating agents (HMAs) in newly diagnosed acute myeloid leukemia (AML) patients. We conducted a single-center, propensity-adjusted retrospective cohort study to compare composite complete remission (CCR) rates, median overall survival (m-OS) and median event-free survival (m-EFS). A total of 170 adult AML patients were treated with first-line azacitidine (AZA) or decitabine (DEC) +/- VEN. Median age was 71 years and 99 (58%) were male. Median follow-up in HMA and HMA-VEN groups was 79 and 21 months. Treatments included AZA alone (n=35, 21%), DEC alone (n=84, 49%), AZA-VEN (n=24, 14%) and DEC-VEN (n=27, 16%). VEN improved CCR rates to HMAs overall (52% vs. 27%, P<0.05) and to AZA (54% vs. 10%, P<0.05), but not to DEC (43% vs. 32%, P=0.35); it did not improve OS, and only improved EFS for AZA (10.5 vs. 3.8 months, P<0.05). CCR rates were lower with AZA than with DEC (13% vs. 33%, P<0.05), but OS and EFS were not different statistically. CCR rates did not differ for AZA-VEN vs. DEC-VEN (CCR: 58% vs. 52%, P=0.66), but OS and EFS were longer for AZA-VEN (m-OS: 12.3 vs. 2.2 months, P<0.05; m-EFS: 9.2 vs. 2.1 months, P<0.05). Our analysis showed that combining VEN with AZA in newly diagnosed AML patients improved outcomes, but combining VEN with DEC did not. AZA-VEN was associated with improved outcomes compared to DEC-VEN. Further studies are needed to test the benefit of combining VEN with DEC.

Impact of IDH1 c.315C>T SNP on Outcomes in Acute Myeloid Leukemia: A Propensity Score-Adjusted Cohort Study.

Acute myeloid leukemia (AML) is the common type of acute leukemia in adults. Definitive prognostic significance of variants of unknown significance lacks for many commonly mutated genes, including the isocitrate dehydrogenase 1 (IDH1) synonymous single nucleotide polymorphism (SNP) variant c.315C>T. In this retrospective cohort study of 248 AML patients at the University of Maryland Greenebaum Comprehensive Cancer Center, we show that the IDH1 c.315C>T SNP, previously reported to be associated with poor prognosis by other studies with conflicting data, does not confer worse prognosis, with a median overall survival (OS) of 17.1 months compared to 15.1 months for patients without this SNP (P=0.57). The lack of negative effect on prognosis by IDH1 SNP c.315C>T is consistent with the absence of amino acid alteration (p.Gly105Gly).

Translatome changes in acute myeloid leukemia cells post exposure to pegcrisantaspase and venetoclax.

The clinical outcomes of patients with acute myeloid leukemia (AML) treated with available therapy remain unsatisfactory. We recently reported that the BCL-2 inhibitor venetoclax synergizes with pegcrisantaspase (Ven-PegC) and exhibits remarkable in vivo efficacy in a preclinical model of AML with complex karyotype. The Ven-PegC combination blocks synthesis of proteins in AML cells by inhibiting cap-dependent translation of mRNA. To further explore the impact of Ven-PegC on protein translation, we used polysome profiling and high-throughput RNA sequencing to characterize Ven-PegC-dependent changes to the translatome. Here we report that the translation of five mRNAs, including two microRNAs, one rRNA, and two mitochondrial genes, was altered after exposure to all three treatments (Ven, PegC, and Ven-PegC). We focused our translatome validation studies on six additional genes related to translational efficiency that were modified by Ven-PegC. Notably, Ven-PegC treatment increased the RNA translation and protein levels of Tribbles homologue 3 (TRIB3), eukaryotic translation initiation factor 3 subunit C (eIF3C), doublesex and mab-3-related transcription factor 1 (DMRT1), and salt-inducible kinase 1 (SIK1). We validated the observed changes in gene/protein expression in vitro and confirmed our cell line-based studies in the bone marrow of an AML patient-derived xenograft model after Ven-PegC treatment. These results support examining alterations in the translatome post chemotherapy to offer insight into the drug's mechanism of action and to inform future therapeutic decisions.

Phase I Clinical Trial of DNA Methyltransferase Inhibitor Decitabine and PARP Inhibitor Talazoparib Combination Therapy in Relapsed/Refractory Acute Myeloid Leukemia.

PURPOSE: Patients with acute myeloid leukemia (AML) unfit for, or resistant to, intensive chemotherapy are often treated with DNA methyltransferase inhibitors (DNMTi). Novel combinations may increase efficacy. In addition to demethylating CpG island gene promoter regions, DNMTis enhance PARP1 recruitment and tight binding to chromatin, preventing PARP-mediated DNA repair, downregulating homologous recombination (HR) DNA repair, and sensitizing cells to PARP inhibitor (PARPi). We previously demonstrated DNMTi and PARPi combination efficacy in AML in vitro and in vivo. Here, we report a phase I clinical trial combining the DNMTi decitabine and the PARPi talazoparib in relapsed/refractory AML. PATIENTS AND METHODS: Decitabine and talazoparib doses were escalated using a 3 + 3 design. Pharmacodynamic studies were performed on cycle 1 days 1 (pretreatment), 5 and 8 blood blasts. RESULTS: Doses were escalated in seven cohorts [25 patients, including 22 previously treated with DNMTi(s)] to a recommended phase II dose combination of decitabine 20 mg/m2 intravenously daily for 5 or 10 days and talazoparib 1 mg orally daily for 28 days, in 28-day cycles. Grade 3-5 events included fever in 19 patients and lung infections in 15, attributed to AML. Responses included complete remission with incomplete count recovery in two patients (8%) and hematologic improvement in three. Pharmacodynamic studies showed the expected DNA demethylation, increased PARP trapping in chromatin, increased γH2AX foci, and decreased HR activity in responders. γH2AX foci increased significantly with increasing talazoparib doses combined with 20 mg/m2 decitabine. CONCLUSIONS: Decitabine/talazoparib combination was well tolerated. Expected pharmacodynamic effects occurred, especially in responders.

Arsenic trioxide dose capping to decrease toxicity in the treatment of acute promyelocytic leukemia.

Arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) combination therapy yields high complete remission and disease-free survival rates in acute promyelocytic leukemia (APL). ATO is dosed on actual body weight and high ATO doses in overweight patients may contribute to increased toxicity. We performed a retrospective, two-center study comparing toxicities in patients who received the Lo-Coco et al ATRA/ATO regimen with capped ATO, ≤10 mg/dose, and non-capped ATO, >10 mg/dose. A total of 44 patients were included; 15 received doses ≤10 mg and 29 received >10 mg. During induction, there was no difference in the incidence of grade ≥3 hepatotoxicity, grade ≥3 QTc prolongation, neurotoxicity, and cardiac toxicity between groups. In consolidation, patients receiving >10 mg/dose experienced a greater incidence of neurotoxicity (66.7% vs 22.2%; p = 0.046). Capping doses saved $24634.37/patient and reduced waste of partially-used vials. At a median follow-up of 27 months, no disease relapses occurred in either group. This represents an opportunity to improve the safety profile of this highly effective regimen.