Final phase I substudy results of ivosidenib in patients with mutant IDH1 relapsed/refractory myelodysplastic syndrome.

Ivosidenib is a first-in-class mutant isocitrate dehydrogenase 1 (mIDH1) inhibitor and has shown efficacy and tolerability in patients with advanced mIDH1 hematologic malignancies, leading to approval in front-line and relapsed/refractory (R/R) mIDH1 AML populations. We report final data from a phase I single-arm substudy (NCT02074839) of patients with R/R mIDH1 MDS following failure of standard-of-care therapies. Oral ivosidenib was taken once daily on days 1-28 in 28-day cycles. Primary objectives were to determine safety, tolerability, and clinical activity. The primary efficacy endpoint was the complete remission + partial remission (CR+PR) rate. Nineteen patients were enrolled; 18 were included in the efficacy analysis. Treatment-related adverse events occurred in eight (42.1%) patients, including a grade 1 QT interval prolongation in one (5.3%) patient and grade 2 differentiation syndrome in two (10.5%) patients. Rates of CR+PR and objective response (CR +PR+marrow CR) were 38.9% (95% confidence interval [CI]: 17.3, 64.3) and 83.3% (95% CI: 58.6, 96.4), respectively. Kaplan-Meier estimates showed a 68.6% probability of patients in CR achieving a remission duration of >=5 years, and a median OS of 35.7 months. Of note, 71.4% and 75.0% baseline red blood cell (RBC) and platelet transfusion-dependent patients, respectively, became transfusion independent (TI; no transfusion >=56 days); 81.8% and 100% of baseline RBC and platelet TI patients, respectively, remained TI. One (5.3%) patient proceeded to a hematopoietic stem cell transplant by data cut-off. In conclusion, ivosidenib is clinically active, with durable remissions and a manageable safety profile observed in patients with mIDH1 R/R MDS.

A study to assess the efficacy of enasidenib and risk-adapted addition of azacitidine in newly diagnosed IDH2-mutant AML.

ABSTRACT: Enasidenib (ENA) is an inhibitor of isocitrate dehydrogenase 2 (IDH2) approved for the treatment of patients with IDH2-mutant relapsed/refractory acute myeloid leukemia (AML). In this phase 2/1b Beat AML substudy, we applied a risk-adapted approach to assess the efficacy of ENA monotherapy for patients aged ≥60 years with newly diagnosed IDH2-mutant AML in whom genomic profiling demonstrated that mutant IDH2 was in the dominant leukemic clone. Patients for whom ENA monotherapy did not induce a complete remission (CR) or CR with incomplete blood count recovery (CRi) enrolled in a phase 1b cohort with the addition of azacitidine. The phase 2 portion assessing the overall response to ENA alone demonstrated efficacy, with a composite complete response (cCR) rate (CR/CRi) of 46% in 60 evaluable patients. Seventeen patients subsequently transitioned to phase 1b combination therapy, with a cCR rate of 41% and 1 dose-limiting toxicity. Correlative studies highlight mechanisms of clonal elimination with differentiation therapy as well as therapeutic resistance. This study demonstrates both efficacy of ENA monotherapy in the upfront setting and feasibility and applicability of a risk-adapted approach to the upfront treatment of IDH2-mutant AML. This trial is registered at www.clinicaltrials.gov as #NCT03013998.

Oral decitabine-cedazuridine versus intravenous decitabine for myelodysplastic syndromes and chronic myelomonocytic leukaemia (ASCERTAIN): a registrational, randomised, crossover, pharmacokinetics, phase 3 study.

BACKGROUND: The DNA methyltransferase inhibitors azacitidine and decitabine for individuals with myelodysplastic syndromes or chronic myelomonocytic leukaemia are available in parenteral form. Oral therapy with similar exposure for these diseases would offer potential treatment benefits. We aimed to compare the safety and pharmacokinetics of oral decitabine plus the cytidine deaminase inhibitor cedazuridine versus intravenous decitabine. METHODS: We did a registrational, multicentre, open-label, crossover, phase 3 trial of individuals with myelodysplastic syndromes or chronic myelomonocytic leukaemia and individuals with acute myeloid leukaemia, enrolled as separate cohorts; results for only participants with myelodysplastic syndromes or chronic myelomonocytic leukaemia are reported here. In 37 academic and community-based clinics in Canada and the USA, we enrolled individuals aged 18 years or older who were candidates to receive intravenous decitabine, with Eastern Cooperative Oncology Group performance status 0 or 1 and a life expectancy of at least 3 months. Participants were randomly assigned (1:1) to receive 5 days of oral decitabine-cedazuridine (one tablet once daily containing 35 mg decitabine and 100 mg cedazuridine as a fixed-dose combination) or intravenous decitabine (20 mg/m2 per day by continuous 1-h intravenous infusion) in a 28-day treatment cycle, followed by 5 days of the other formulation in the next treatment cycle. Thereafter, all participants received oral decitabine-cedazuridine from the third cycle on until treatment discontinuation. The primary endpoint was total decitabine exposure over 5 days with oral decitabine-cedazuridine versus intravenous decitabine for cycles 1 and 2, measured as area under the curve in participants who received the full treatment dose in cycles 1 and 2 and had decitabine daily AUC0-24 for both oral decitabine-cedazuridine and intravenous decitabine (ie, paired cycles). On completion of the study, all patients were rolled over to a maintenance study. This study is registered with ClinicalTrials.gov, NCT03306264. FINDINGS: Between Feb 8, 2018, and June 7, 2021, 173 individuals were screened, 138 (80%) participants were randomly assigned to a treatment sequence, and 133 (96%) participants (87 [65%] men and 46 [35%] women; 121 [91%] White, four [3%] Black or African-American, three [2%] Asian, and five [4%] not reported) received treatment. Median follow-up was 966 days (IQR 917-1050). Primary endpoint of total exposure of oral decitabine-cedazuridine versus intravenous decitabine was 98·93% (90% CI 92·66-105·60), indicating equivalent pharmacokinetic exposure on the basis of area under the curve. The safety profiles of oral decitabine-cedazuridine and intravenous decitabine were similar. The most frequent adverse events of grade 3 or worse were thrombocytopenia (81 [61%] of 133 participants), neutropenia (76 [57%] participants), and anaemia (67 [50%] participants). The incidence of serious adverse events in cycles 1-2 was 31% (40 of 130 participants) with oral decitabine-cedazuridine and 18% (24 of 132 participants) with intravenous decitabine. There were five treatment-related deaths; two deemed related to oral therapy (sepsis and pneumonia) and three to intravenous treatment (septic shock [n=2] and pneumonia [n=1]). INTERPRETATION: Oral decitabine-cedazuridine was pharmacologically and pharmacodynamically equivalent to intravenous decitabine. The results support use of oral decitabine-cedazuridine as a safe and effective alternative to intravenous decitabine for treatment of individuals with myelodysplastic syndromes or chronic myelomonocytic leukaemia. FUNDING: Astex Pharmaceuticals.

Anti-Spike Antibody Responses in Allogeneic Stem Cell Transplant Recipients to Two Doses of COVID-19 mRNA Vaccination: A Retrospective, Single-Center Analysis.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients were excluded from the initial SARS-CoV-2 mRNA vaccination efficacy trials. Suboptimal vaccine responses have been reported in immunocompromised cohorts such as patients with solid tumors or hematologic malignancies, suggesting the need for additional research. Widespread data on the antibody responses and vaccine efficacy in allo-HSCT recipients is limited. In our single-center, retrospective study, we analyzed the anti-spike IgG antibody responses in 75 allo-HSCT recipients who received a series of two doses of mRNA vaccination. We collected data on previous COVID-19 infection, B and T lymphocyte recovery, donor types, graft-vs.-host disease (GVHD), and immunosuppressive medications at the time of vaccination. With the original variant, a cutoff of 4,160 arbitrary units (AU)/mL has been correlated with a 0.95 probability of a viral neutralization. We also examined the number of allo-HSCT recipients who achieved this conservative threshold. To our knowledge, no correlate exists for the currently prevalent Omicron variant and viral neutralization. Despite 29.3% (22/75) of patients being on systemic immunosuppressive medications due to chronic GVHD, positive antibody responses > 50 AU/mL were seen in 96% of patients. However, only 48% (36/75) of patients were above the neutralizing antibody threshold. Those with previous COVID-19 infection had significantly higher antibody responses. Although encouraging, the variability of the responses underscores the concept of ongoing antibody monitoring as well as consideration of additional doses of the COVID-19 vaccine in this cohort.

Identifying patients at risk for hereditary myeloid malignancy syndromes incorporating a novel, self-administered questionnaire to an initial screening platform.

INTRODUCTION: Four to 10% of cases of myeloid malignancies are inherited. We report our experience on hereditary myeloid malignancy syndromes (HMMS) incorporating a novel questionnaire in the screening platform for patients with myeloid malignancies and aplastic anemia. METHODS: The questionnaire was sent via electronic patient portal prior to clinic visits. Patients screened positive based on responses to questionnaire items, presence of suspicion disease characteristics (young age, family history, monosomy 7 etc.) and/or presence of signs of HMMS. Those deemed at-risk based on questionnaire responses, clinical features and/or somatic mutation profile were offered germline testing. RESULTS: A total of 408 patients were screened, 141 (35%) were deemed at-risk. Fifty-four (38%) of at-risk patients were seen in the genetics clinic. Forty-one (76%) of the patients seen agreed to germline testing and 13 declined due to cost or personal decision. Twenty pathogenic (P)/likely-pathogenic (LP) germline mutations were identified in 16 (39%) of the tested patients. Five patients also had a variant of uncertain significance (VUS) and an additional 13 had at least 1 VUS without P/LP mutations (total 29 VUS's were found in 18 (44%) of tested patients). The median age of diagnosis for patients with P/LP mutations was 56 years versus 66 years in the entire cohort. CONCLUSION: Incorporating an electronic questionnaire is an effective screening method for HMMS. Many patients declined testing due to cost. These results highlight the importance of germline testing in patients with myeloid malignancies, further research in HMMS, and coverage by healthcare plans.

Samples from patients with AML show high concordance in detection of mutations by NGS at local institutions vs central laboratories.

Next-generation sequencing (NGS) to identify pathogenic mutations is an integral part of acute myeloid leukemia (AML) therapeutic decision-making. The concordance in identifying pathogenic mutations among different NGS platforms at different diagnostic laboratories has been studied in solid tumors but not in myeloid malignancies to date. To determine this interlaboratory concordance, we collected a total of 194 AML bone marrow or peripheral blood samples from newly diagnosed patients with AML enrolled in the Beat AML Master Trial (BAMT) at 2 academic institutions. We analyzed the diagnostic samples from patients with AML for the detection of pathogenic myeloid mutations in 8 genes (DNMT3A, FLT3, IDH1, IDH2, NPM1, TET2, TP53, and WT1) locally using the Hematologic Neoplasm Mutation Panel (50-gene myeloid indication filter) (site 1) or the GeneTrails Comprehensive Heme Panel (site 2) at the 2 institutions and compared them with the central results from the diagnostic laboratory for the BAMT, Foundation Medicine, Inc. The overall percent agreement was over 95% each in all 8 genes, with almost perfect agreement (κ > 0.906) in all but WT1, which had substantial agreement (κ = 0.848) when controlling for site. The minimal discrepancies were due to reporting variants of unknown significance (VUS) for the WT1 and TP53 genes. These results indicate that the various NGS methods used to analyze samples from patients with AML enrolled in the BAMT show high concordance, a reassuring finding given the wide use of NGS for therapeutic decision-making in AML.

SARS-CoV-2 Vaccination IgG Antibody Responses in Patients with Hematologic Malignancies in a Myeloid Enriched Cohort: A Single Center Observation.

OBJECTIVE: Patients diagnosed with hematologic malignancies are at increased risk for severe SARS-CoV-2 infection. We evaluated the serological IgG response following two doses of the SARS-CoV-2 vaccine in patients with hematologic malignancies. METHODS: Patients treated at UT Southwestern Medical Center with a diagnosis of a myeloid or lymphoid neoplasm were included. SARS-CoV-2 vaccination response was defined as a positive quantifiable spike IgG antibody titer. RESULTS: Sixty patients were included in the study and 60% were diagnosed with a myeloid neoplasm. The majority (85%) of the patients with a myeloid malignancy and 50% of the patients with a lymphoid malignancy mounted a serological response after receiving two doses of the vaccine. CONCLUSION: Vaccination should be offered irrespective of ongoing treatment or active disease. Findings require validation in a larger cohort of patients.

Entospletinib with decitabine in acute myeloid leukemia with mutant TP53 or complex karyotype: A phase 2 substudy of the Beat AML Master Trial.

BACKGROUND: Patients with acute myeloid leukemia (AML) who have tumor protein p53 (TP53) mutations or a complex karyotype have a poor prognosis, and hypomethylating agents are often used. The authors evaluated the efficacy of entospletinib, an oral inhibitor of spleen tyrosine kinase, combined with decitabine in this patient population. METHODS: This was a multicenter, open-label, phase 2 substudy of the Beat AML Master Trial (ClinicalTrials.gov identifier NCT03013998) using a Simon two-stage design. Eligible patients aged 60 years or older who had newly diagnosed AML with mutations in TP53 with or without a complex karyotype (cohort A; n = 45) or had a complex karyotype without TP53 mutation (cohort B; n = 13) received entospletinib 400 mg twice daily with decitabine 20 mg/m2 on days 1-10 every 28 days for up to three induction cycles, followed by up to 11 consolidation cycles, in which decitabine was reduced to days 1-5. Entospletinib maintenance was given for up to 2 years. The primary end point was complete remission (CR) and CR with hematologic improvement by up to six cycles of therapy. RESULTS: The composite CR rates for cohorts A and B were 13.3% (95% confidence interval, 5.1%-26.8%) and 30.8% (95% confidence interval, 9.1%-61.4%), respectively. The median duration of response was 7.6 and 8.2 months, respectively, and the median overall survival was 6.5 and 11.5 months, respectively. The study was stopped because the futility boundary was crossed in both cohorts. CONCLUSIONS: The combination of entospletinib and decitabine demonstrated activity and was acceptably tolerated in this patient population; however, the CR rates were low, and overall survival was short. Novel treatment strategies for older patients with TP53 mutations and complex karyotype remain an urgent need.

Real-world outcomes of frontline venetoclax-based therapy in older adults with acute myeloid leukemia: an analysis utilizing EHR data.

Venetoclax (VEN) in combination with hypomethylating agents (HMA) or low-dose cytarabine has become the standard of care for patients with acute myeloid leukemia (AML) who are ineligible to receive intensive induction chemotherapy. Clinical trials are performed in a controlled setting that can be difficult to emulate in the real world. We sought to investigate outcomes of patients treated with VEN-based therapy in the real world. Patients with an age of ≥65 years who received frontline VEN-based therapy were identified using the COTA database (n = 112). The majority of patients (91%) were treated in the community setting and had adverse-risk AML (63%). The real-world overall response rate (rwORR) was 55% with a median real-world overall survival (rwOS) of 13 months after VEN/HMA. The rwORR was lower and median rwOS was shorter than those reported in the VIALE-A trial, underscoring the importance of studying novel therapies using real-world data.

Post-transplant cyclophosphamide and early mixed donor Chimerism in myeloid malignancies; a single-center experience.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative option for high-risk myeloid malignancies. Post-transplant cyclophosphamide (PT-Cy) has proven to be effective for graft versus host disease (GVHD) prophylaxis. Given that graft-versus-tumor (GVT) effect plays a major role in reducing the risk of disease relapse, the application of PT-Cy must balance the risk of relapse. Mixed chimerism (MC) refers to a state of concurrent presence of recipient and donor cells post allo-HSCT which may precede relapse disease. OBJECTIVE: We investigated the impact of PT-Cy on early MC (EMC) and disease relapse in patients with a myeloid malignancy post allo-HSCT. STUDY DESIGN: This retrospective single-center study included patients that underwent allo-HSCT between 2015 and 2021. Patient and disease characteristics were collected from the electronic health records. EMC was defined as <95% donor cells at day 90-120 post allo-HSCT. RESULTS: A total of 144 patient that received an allo-HSCT were included in the study. One hundred and eight (75%) patients received PT-Cy as part of the GVHD prophylaxis regimen. The majority underwent allo-HSCT for acute myeloid leukemia (62%) or myelodysplastic syndrome (31%). Sixty-five percent received allo-HSCT from a matched unrelated donor transplant and 65% received a myeloablative conditioning regimen. A lower rate of chronic GVHD (p = 0.03) and a higher rate of EMC (p = 0.04) were observed in patients that received PT-Cy. PT-Cy was not associated with overall survival (OS) and relapse-free survival (RFS). Multivariable analysis identified measurable residual disease status (p = 0.003), hematopoietic cell transplantation-specific comorbidity index (p = 0.012) and chronic GVHD (p = 0.006) as independent prognostic variables for OS. AML-adverse risk (p = 0.004) and EMC (p = 0.018) were independently prognostic for RFS. While EMC overall was not significantly associated with higher risk of relapse, EMC was associated with shorter RFS within adverse-risk AML patients. CONCLUSION: Our study shows that PT-Cy was associated with an increased risk of EMC. The predictive value of EMC for relapse remains unclear and may depend on the underlying disease, which should be validated in a larger cohort.

Image-guidance triggered adaptive radiation therapy in head and neck squamous cell carcinoma: single-institution experience and implications for clinical practice.

PURPOSE: To report frequency and timing of adaptive radiotherapy (ART) and assess patient, disease, and treatment-related characteristics potentially triggering the need for such adaptive replanning in head and neck squamous cell carcinoma (HNSCC). METHODS: Medical records of HNSCC patients treated with definitive intensity modulated radiation therapy (IMRT) with or without concurrent systemic chemotherapy were reviewed retrospectively to identify patients undergoing image-guidance triggered adaptive replanning. Clinico-demographic characteristics of patients undergoing ART were compared with patients treated without adaptation using the chi-square test. RESULTS: Two hundred patients with squamous cell cancers of the oropharynx, larynx, or hypopharynx treated with definitive IMRT between 2014 to 2019 comprised the study cohort. Twenty-seven (13.5%) patients underwent adaptive replanning during treatment at a median of 17 fractions (inter-quartile range 14-24 fractions). There were no significant differences in the baseline patient (age, gender), disease (site of primary, staging/grouping), and treatment-related characteristics (dose-fractionation, chemotherapy usage) in patients undergoing ART compared to those treated without adaptation. Weight loss during IMRT emerged as a significant factor predicting the need for ART; patients having ≥10% weight loss from baseline were more likely to undergo treatment adaptation compared to patients with <10% weight loss (p = 0.0002). There was variable impact of ART on dose-volume statistics of organs-at-risk such parotid glands and spinal cord. CONCLUSION: Image-guidance triggered ART for HNSCC is not associated with significant improvement in OAR dosimetry. However, weight loss during definitive IMRT can be a potentially useful trigger for identifying patients who are most likely to benefit from such adaptive replanning.

Disabling Uncompetitive Inhibition of Oncogenic IDH Mutations Drives Acquired Resistance.

Mutations in IDH genes occur frequently in acute myeloid leukemia (AML) and other human cancers to generate the oncometabolite R-2HG. Allosteric inhibition of mutant IDH suppresses R-2HG production in a subset of patients with AML; however, acquired resistance emerges as a new challenge, and the underlying mechanisms remain incompletely understood. Here we establish isogenic leukemia cells containing common IDH oncogenic mutations by CRISPR base editing. By mutational scanning of IDH single amino acid variants in base-edited cells, we describe a repertoire of IDH second-site mutations responsible for therapy resistance through disabling uncompetitive enzyme inhibition. Recurrent mutations at NADPH binding sites within IDH heterodimers act in cis or trans to prevent the formation of stable enzyme-inhibitor complexes, restore R-2HG production in the presence of inhibitors, and drive therapy resistance in IDH-mutant AML cells and patients. We therefore uncover a new class of pathogenic mutations and mechanisms for acquired resistance to targeted cancer therapies. SIGNIFICANCE: Comprehensive scanning of IDH single amino acid variants in base-edited leukemia cells uncovers recurrent mutations conferring resistance to IDH inhibition through disabling NADPH-dependent uncompetitive inhibition. Together with targeted sequencing, structural, and functional studies, we identify a new class of pathogenic mutations and mechanisms for acquired resistance to IDH-targeting cancer therapies. This article is highlighted in the In This Issue feature, p. 1.

The impact of race and ethnicity on outcomes of patients with myelodysplastic syndromes: a population-based analysis.

Race and ethnic backgrounds affect the disease characteristics and clinical outcomes in many cancers, including acute myeloid leukemia; however, the association of race/ethnicity on myelodysplastic syndrome (MDS) is still controversial. Therefore, we aimed to study the impact of race/ethnicity on the disease characteristics and survival outcomes in patients with MDS. Adult patients with MDS diagnosed in 2004-2016 were selected using the SEER database. Race/ethnicity was categorized as non-Hispanic White (NHW), non-Hispanic Black (NHB), and Hispanic. Hispanic and NHB patients had significantly lower incidence rate ratio (IRR) in age group ≥01 years (p < .001) compared to NHW; however, in the age group <50 years, NHB patients had significantly higher IRR with an increased incidence rate of 49%. NHB patients had better overall survival than Hispanic and NHW patients (p < .001), even after adjusting for confounding variables. MDS have significant differences in age at diagnosis, disease risk, and survival outcomes based on racial/ethnic backgrounds.

Identification and prioritization of myeloid malignancy germline variants in a large cohort of adult patients with AML.

Inherited predisposition to myeloid malignancies is more common than previously appreciated. We analyzed the whole-exome sequencing data of paired leukemia and skin biopsy samples from 391 adult patients from the Beat AML 1.0 consortium. Using the 2015 American College of Medical Genetics and Genomics (ACMG) guidelines for variant interpretation, we curated 1547 unique variants from 228 genes. The pathogenic/likely pathogenic (P/LP) germline variants were identified in 53 acute myeloid leukemia (AML) patients (13.6%) in 34 genes, including 6.39% (25/391) of patients harboring P/LP variants in genes considered clinically actionable (tier 1). 41.5% of the 53 patients with P/LP variants were in genes associated with the DNA damage response. The most frequently mutated genes were CHEK2 (8 patients) and DDX41 (7 patients). Pathogenic germline variants were also found in new candidate genes (DNAH5, DNAH9, DNMT3A, and SUZ12). No strong correlation was found between the germline mutational rate and age of AML onset. Among 49 patients who have a reported history of at least one family member affected with hematological malignancies, 6 patients harbored known P/LP germline variants and the remaining patients had at least one variant of uncertain significance, suggesting a need for further functional validation studies. Using CHEK2 as an example, we show that three-dimensional protein modeling can be one of the effective methodologies to prioritize variants of unknown significance for functional studies. Further, we evaluated an in silico approach that applies ACMG curation in an automated manner using the tool for assessment and (TAPES) prioritization in exome studies, which can minimize manual curation time for variants. Overall, our findings suggest a need to comprehensively understand the predisposition potential of many germline variants in order to enable closer monitoring for disease management and treatment interventions for affected patients and families.

Safety and Efficacy of a DNA Oligonucleotide Therapy in Patients with Relapsed or Refractory Diffuse Large B-Cell Lymphoma.

BACKGROUND: PNT2258 is a liposomal formulation that encapsulates multiple copies of PNT100, a native, chemically unmodified, 24-base DNA oligonucleotide designed to target the regulatory region upstream of the B-cell lymphoma 2 (BCL2) gene. METHODS: This phase II, multicenter, single-arm, open-label, 2-stage design study investigated the single-agent activity of PNT2258 in patients with relapsed/refractory DLBCL. Initially, patients had to have a performance status (PS) of ≤2 and prior exposure to CD20-targeted therapy, an alkylating agent, and a steroid with no upper limit. Criteria were modified to PS of 0 or 1 and at least 1 to ≤3 prior therapies (identified as the target population) after observing an initially high frequency of rapid disease progression in patients with extensive prior therapies or poor PS. RESULTS: The study was stopped early following an interim analysis, despite surpassing the protocol predetermined futility boundary, because the ORR was below the expectations of response in an evolving DLBCL treatment landscape. The final analysis included all 45 enrolled patients and demonstrated an ORR of 11%. In the response evaluable subset (n = 26), defined as patients in the target population with exposure to ≥8 doses of PNT2258 within the first 35 days and evaluable baseline/post-baseline scans, the ORR was 19%. The most common adverse events were fatigue (44%), nausea (42%), diarrhea (40%), pyrexia (36%), anemia (32%), and vomiting (27%). CONCLUSIONS: PNT2258 was well-tolerated in a chemotherapy refractory DLBCL population. Despite demonstration of single-agent activity, ORR was lower than acceptable for further new therapy development.

Volumetric Modulated Arc Therapy Enabled Total Body Irradiation (VMAT-TBI): Six-year Clinical Experience and Treatment Outcomes.

Total body irradiation is an important part of the conditioning regimens frequently used to prepare patients for allogeneic hematopoietic stem cell transplantation (SCT). Volumetric-modulated arc therapy enabled total body irradiation (VMAT-TBI), an alternative to conventional TBI (cTBI), is a novel radiotherapy treatment technique that has been implemented and investigated in our institution. The purpose of this study is to (1) report our six-year clinical experience in terms of treatment planning strategy and delivery time and (2) evaluate the clinical outcomes and toxicities in our cohort of patients treated with VMAT-TBI. This is a retrospective single center study. Forty-four patients at our institution received VMAT-TBI and chemotherapy conditioning followed by allogeneic SCT between 2014 and 2020. Thirty-two patients (73%) received standard-dose TBI (12-13.2 Gy in 6-8 fractions twice daily), whereas 12 (27%) received low-dose TBI (2-4 Gy in one fraction). Treatment planning, delivery, and treatment outcome data including overall survival (OS), relapse-free survival (RFS), and toxicities were analyzed. The developed VMAT-TBI planning strategy consistently generated plans satisfying our dose constraints, with planning target volume coverage >90%, mean lung dose ∼50% to 75% of prescription dose, and minimal hotspots in critical organs. Most of the treatment deliveries were <100 minutes (range 33-147, mean 72). The median follow-up was 26 months. At the last follow-up, 34 of 44 (77%) of patients were alive, with 1- and 2-year OS of 90% and 79% and RFS of 88% and 71%, respectively. The most common grade 3+ toxicities observed were mucositis (31 patients [71%]) and nephrotoxicity (6 patients [13%]), both of which were deemed multifactorial in cause. Four patients (9%) in standard-dose cohort developed grade 3+ pneumonitis, with 3 cases in the setting of documented respiratory infection and only 1 (2%) deemed likely related to radiation alone. VMAT-TBI provides a safe alternative to cTBI. The dose modulation capability of VMAT-TBI may lead to new treatment strategies, such as simultaneous boost and further critical organ sparing, for better malignant cell eradication, immune suppression, and lower toxicities.

Risk, Characteristics and Biomarkers of Cytokine Release Syndrome in Patients with Relapsed/Refractory AML or MDS Treated with CD3xCD123 Bispecific Antibody APVO436.

We evaluate the risk, characteristics and biomarkers of treatment-emergent cytokine release syndrome (CRS) in patients with relapsed/refractory acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) who received APVO436 during the dose-escalation phase of a Phase 1B study (ClinicalTrials.gov, identifier: NCT03647800). Of four patients who developed Grade ≥ 3 CRS, two received steroid prophylaxis. The dose level, gender, race, obesity, or baseline hematologic parameters in peripheral blood did not predict the risk of CRS. Patients with a higher leukemia burden as determined by a higher total WBC, higher percentage of blasts in bone marrow, or higher percentage of blasts in peripheral blood (by hematopathology or immunophenotyping) did not have a higher incidence of CRS. There was an age difference between patients who did versus patients who did not develop CRS (72.9 ± 1.6 years (Median 73.5 years) vs. 63.3 ± 2.3 years (Median: 65.0 years), which was borderline significant (p = 0.04). Premedication with steroids did not eliminate the risk of CRS. Cytokine profiling in patients who developed CRS after APVO436 infusion indicates that the predominant cytokine in this inflammatory cytokine response was IL-6. APVO436-associated CRS was generally manageable with tocilizumab with or without dexamethasone. Notably, the development of CRS after APVO436 therapy did not appear to be associated with a response. The prolonged stabilization of disease, partial remissions and complete remissions were achieved in both patients who experienced CRS, as well as patients who did not experience CRS after APVO436 infusions.

A Clinical Phase 1B Study of the CD3xCD123 Bispecific Antibody APVO436 in Patients with Relapsed/Refractory Acute Myeloid Leukemia or Myelodysplastic Syndrome.

APVO436 is a recombinant T cell-engaging humanized bispecific antibody designed to redirect host T cell cytotoxicity in an MHC-independent manner to CD123-expressing blast cells from patients with hematologic malignancies and has exhibited single-agent anti-leukemia activity in murine xenograft models of acute myeloid leukemia (AML). In this first-in-human (FIH) multicenter phase 1B study, we sought to determine the safety and tolerability of APVO436 in R/R AML/myelodysplastic syndrome (MDS) patients and identify a clinically active recommended phase 2 dose (RP2D) level for its further clinical development. A total of 46 R/R AML/MDS patients who had failed 1-8 prior lines of therapy received APVO436 as weekly intravenous (IV) infusions at 10 different dose levels, ranging from a Minimum Anticipated Biological Effect Level (MABEL) of 0.3 mcg to 60 mcg. APVO436 exhibited a favorable safety profile with acceptable tolerability and manageable drug-related adverse events (AEs), and its maximum tolerated dose (MTD) was not reached at a weekly dose of 60 mcg. The most common APVO436-related AEs were infusion-related reactions (IRR) occurring in 13 (28.3%) patients and cytokine release syndrome (CRS) occurring in 10 (21.7%). The single dose RP2D level was identified as 0.2 mcg/kg. Preliminary efficacy signals were observed in both AML and MDS patients: Prolonged stable disease (SD), partial remissions (PR), and complete remissions (CR) were observed in R/R AML patients as best overall responses to APVO436 at the RP2D level. Three of six evaluable MDS patients had marrow CRs. The safety and preliminary evidence of efficacy of APVO436 in R/R AML and MDS patients warrant further investigation of its clinical impact potential.