Pharmacokinetic/Pharmacodynamic Evaluation of Ivosidenib or Enasidenib Combined With Intensive Induction and Consolidation Chemotherapy in Patients With Newly Diagnosed IDH1/2-Mutant Acute Myeloid Leukemia

Mutant isocitrate dehydrogenase 1/2 (mIDH1/2) proteins catalyze production of the oncometabolite D-2-hydroxyglutarate (2-HG). Ivosidenib and enasidenib are oral inhibitors of mIDH1 and mIDH2, respectively. An open-label phase 1 study is evaluating the safety and efficacy of ivosidenib or enasidenib combined with intensive induction and consolidation chemotherapy in adult patients with newly diagnosed mIDH1/2 acute myeloid leukemia (AML; NCT02632708). In this population, we characterized the pharmacokinetics (PK), pharmacodynamics (PD), and PK/PD relationships for ivosidenib and enasidenib. Patients received continuous oral ivosidenib 500 mg once daily or enasidenib 100 mg once daily combined with chemotherapy. Serial blood samples were collected for measurement of the concentrations of the mIDH inhibitors. 2-HG concentrations were measured in both plasma and bone marrow aspirates. Samples were collected from 60 patients receiving ivosidenib and 91 receiving enasidenib. For both drugs, exposures at steady state were higher than after single doses, with mean accumulation ratios (based on area under the plasma concentration-time curve from time 0 to 24 hours) of 2.35 and 8.25 for ivosidenib and enasidenib, respectively. Mean plasma 2-HG concentrations were elevated at baseline. After multiple ivosidenib or enasidenib doses, mean trough plasma 2-HG concentrations decreased to levels observed in healthy individuals and were maintained with continued dosing. There was a corresponding reduction in bone marrow 2-HG concentrations. When combined with intensive chemotherapy in patients with newly diagnosed mIDH1/2 AML, ivosidenib and enasidenib demonstrated PK/PD profiles similar to those when they are given as single agents. These findings support the dosing of ivosidenib or enasidenib in combination with intensive chemotherapy for the treatment of patients with newly diagnosed mIDH1/2 AML.

495 Trial of SNX281, a systemically delivered small molecule STING agonist, in solid tumors and lymphomas

Background

Innate immune activation is a desirable goal in anticancer therapy. Stimulator of Interferon Genes (STING) agonists represent one approach to this goal; to date most studies have utilized intra-tumoral administration. SNX281 is a novel small molecule agonist of human and mammalian STING with favorable pharmacokinetic properties thatto enable systemic intravenous administration. The molecule dimerizes in the binding site of STING to induce activation. In preclinical studies using THP-1 cells or human PBMCs, SNX281 caused both pathway activation and the induction of signature cytokines, IFN-b, TNF-a and IL-6 in a STING dependent manner. Intravenously delivered SNX281 caused complete and durable tumor regression in mice bearing CT26 colon carcinomas with induction of immune memory. Mice that were cured of their primary CT26 tumors were completely resistant to re-challenge. Increased T cell responses were observed against the endogenous CT26 rejection antigen AH1. Maximal tumor control depended on CD8+ T cells, confirming the involvement of an adaptive immune component in SNX281 mediated anti-tumor activity, although some tumor control was observed even in the absence of T cells. In addition, combining STING-dependent T cell priming induced by SNX281 with anti-PD-1 resulted in robust antitumor activity and significant survival benefit in multiple tumor models (CT26, MC38 and B16- F10) that are resistant to checkpoint therapy alone.

Methods

This is a multicenter, open-label, phase I dose-escalation followed by dose expansion study of SNX281 as monotherapy and in combination with pembrolizumab. SNX281 is administered as a 30-minute intravenous infusion QW for 3 weeks followed by Q3W for six cycles. Eligible patients for the dose escalation phase will have, among other criteria, histologically confirmed advanced solid tumors or lymphomas which have failed prior therapy and/or are not eligible for therapies, as well as adequate organ function, life expectancy of at least 12 weeks, and measurable disease. Monotherapy dose escalation accrued initially with single patient cohorts advancing to a 3+3 design. The dose expansion phases of each treatment arm will begin following the determination of an MTD or alternative dose of SNX281 in each respective treatment arm. The single-agent treatment arm of SNX281 is planned to evaluate at least 2 expansion cohorts in ovarian cancer and colorectal carcinoma while the combination treatment arm of SNX281 and pembrolizumab is planned to enroll subjects with advanced cancer who have relapsed on or have become refractory to prior immune checkpoint therapy given in an indicated setting. Clinical Trial Information: NCT04609579

Trial Registration

NCT04609579

Ethics Approval

IRB approval from IntegReview IORG0000689.

Abstract PR03: A phase 1 trial of AG-270 in patients with advanced solid tumors or lymphoma with homozygous MTAP deletion

Background: Homozygous deletion of MTAP, the gene encoding the metabolic enzyme methylthioadenosine phosphorylase, occurs in ~15% of human malignancies. Tumor cells with this deletion are selectively vulnerable to decreases in the methyl donor S-adenosylmethionine (SAM). AG-270 is a first-in-class, oral, potent, reversible inhibitor of methionine adenosyltransferase 2A (MAT2A), the key enzyme responsible for SAM synthesis. We report preliminary results from an ongoing, first-in-human, phase 1 trial of AG-270 (ClinicalTrials.gov Identifier: NCT03435250). Aims: The primary objective of this study is to determine the maximum tolerated dose (MTD) of AG-270. Secondary objectives include safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and efficacy. Methods: Eligibility requires homozygous deletion of cyclin dependent kinase inhibitor 2A (CDKN2A) in the patient’s tumor (as MTAP is usually co-deleted with CDKN2A), or loss of MTAP by IHC. Patients receive AG-270 daily in 28-day cycles, with intensive PK/PD sampling after the first dose and after 2 weeks of treatment. Paired tumor biopsies are collected at baseline and at the end of cycle 1. Disease evaluation is performed every 2 cycles. Results: As of 20 May 2019, 39 patients had been treated with AG-270: 50 mg once daily (QD; n=3), 100 mg QD (n=7), 150 mg QD (n=6), 200 mg QD (n=11), 400 mg QD (n=6), or 200 mg twice daily (BID; n=6). AG-270 was well absorbed. Plasma concentrations increased in a dose-proportional manner except at 400 mg QD, where exposure was lower than anticipated. The geometric mean area under the curve from 0-24 h at steady state (AUC0-24,ss) in the QD cohorts ranged from 33200 to 199085 ng*h/mL, and the geometric mean AUC0-24,ss in the 200 mg BID cohort was 254616 ng*h/mL. The median half-life of AG-270 ranged from 16.1 to 38.4 h. Decreases in plasma [SAM] were exposure-dependent. After 2 weeks of dosing, maximal reductions in plasma [SAM] ranged from 51% to 71% across the tested cohorts. Analysis of 9 paired tumor biopsies by IHC showed decreases in levels of symmetrically di-methylated arginine (SDMA) residues, consistent with MAT2A inhibition; the average H-score reduction compared to baseline was 36.4% [-98.8%, +21.4%]. Asymptomatic, exposure-dependent increases in unconjugated bilirubin were observed starting at 100 mg QD, consistent with the known potential of AG-270 to inhibit UGT1A1. Three patients (at 100 mg QD, 150 mg QD, and 200 mg BID) developed grade 2 and 3 diffuse erythematous rashes during the second week of dosing that resolved within 1 week of stopping treatment. Exposure-dependent, reversible decreases in platelet counts were first observed at 200 mg QD and were grade 3 and 4 in severity at 200 mg BID. Two patients treated at 200 mg BID developed reversible but dose-limiting grade 3 and 4 increases in liver enzymes. The MTD of AG-270 is 200 mg QD. An unconfirmed partial response has been observed in a patient with a high-grade neuroendocrine carcinoma of the lung. Seven patients have achieved radiographically confirmed stable disease of 2.0 to 9.9 months’ duration. Conclusions: AG-270 causes reductions in plasma [SAM] and in tumor SDMA levels at well-tolerated doses. This trial will next evaluate the combination of AG-270 with taxane-based chemotherapy, given preclinical data demonstrating enhanced antitumor activity with AG-270 and taxanes in MTAP-deleted cancer models.

Citation Format: Rebecca S Heist, Mrinal M Gounder, Sophie Postel-Vinay, Frederick Wilson, Elena Garralda, Khanh Do, Geoffrey I Shapiro, Patricia Martin-Romano, Gerburg Wulf, Michael Cooper, Caroline Almon, Salah Nabhan, Varsha Iyer, Yanwei Zhang, Kevin Marks, Elia Aguado-Fraile, Frank Basile, Keith Flaherty, Howard A Burris. A phase 1 trial of AG-270 in patients with advanced solid tumors or lymphoma with homozygous MTAP deletion [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr PR03. doi:10.1158/1535-7163.TARG-19-PR03

Effect of itraconazole, food, and ethnic origin on the pharmacokinetics of ivosidenib in healthy subjects

PURPOSE

To assess the effect of ethnicity, food, and itraconazole (strong CYP3A4 inhibitor) on the pharmacokinetics of ivosidenib after single oral doses in healthy subjects.

METHODS

Three phase 1 open-label studies were performed. Study 1: Japanese and Caucasian subjects received single doses of 250, 500, or 1000 mg ivosidenib (NCT03071770). Part 1 of study 2 (a two-period crossover study): subjects received 500 mg ivosidenib after either an overnight fast or a high-fat meal. Subjects received 1000 mg ivosidenib after an overnight fast in the single period of part 2 (NCT02579707). Study 3: in period 1, subjects received 250 mg ivosidenib; then, in period 2, subjects received oral itraconazole (200 mg once daily) on days 1-18, plus 250 mg ivosidenib on day 5 (NCT02831972).

RESULTS

Ivosidenib was well tolerated in all three studies. Study 1: pharmacokinetic profiles were generally comparable, although AUC and C_max were slightly lower in Japanese subjects than in Caucasian subjects, by ~ 30 and 17%, respectively. Study 2: AUC increased by ~ 25% and C_max by ~ 98%, when ivosidenib was administered with a high-fat meal compared with a fasted state. Study 3: co-administration of itraconazole increased ivosidenib AUC by 169% (90% CI 145-195) but had no effect on ivosidenib C_max.

CONCLUSIONS

No ivosidenib dose adjustment is deemed necessary for Japanese subjects. High-fat meals should be avoided when ivosidenib is taken with food. When co-administered with strong CYP3A4 inhibitors, monitoring for QT interval prolongation (a previously defined adverse event of interest) is recommended and an ivosidenib dose interruption or reduction may be considered. CLINICALTRIALS.GOV : NCT03071770, NCT02579707, and NCT02831972.

Comparison of outcomes after single or double cord blood transplantation in adults with acute leukemia using different types of myeloablative conditioning regimen, a retrospective study on behalf of Eurocord and the Acute Leukemia Working Party of EBMT

We report outcomes after single (s) and double (d) umbilical cord blood transplantation (UCBT) after myeloablative conditioning (MAC) regimen for 239 patients transplanted for acute leukemia in first complete remission (CR1). All sUCBT patients received a total nucleated cell dose >2.5 × 10(7)/kg. Conditioning regimen for sUCBT was total body irradiation (TBI)12 Gy- or busulfan (BU)-based ± fludarabine (Flu) (n=68, group 1), thiotepa+BU+Flu (TBF) (n=88, group 2), and for dUCBT it was TBI12 Gy+cyclophosphamide ± Flu (n=83, group 3). dUCBT recipients were younger, received higher cell dose and less frequently antithymocyte globulin. In multivariate analysis, we found similar neutrophil recovery among the three groups; however, acute graft-versus-host disease II-IV was higher in dUCBT compared with others. Non-relapse mortality and relapse incidence were not statistically different among the three groups. Leukemia-free survival was 30% for sUCBT using TBI- or BU-based MAC compared with 48% for sUCBT TBF and 48% for dUCBT (P=0.02 and P=0.03, respectively), and it was not statistically different between sUCBT with TBF and dUCBT. In conclusion, use of sUCBT with adequate cell dose (>2.5 × 10(7)/kg) and a specific conditioning regimen in the MAC setting results in similar outcomes as dUCBT. The choice of TBF conditioning regimen for sUCBT may improve results, and whether this regimen may be effective in dUCBT should be further analyzed.

Taxonomic relatedness between Pectobacterium carotovorum subsp. carotovorum, Pectobacterium carotovorum subsp. odoriferum and Pectobacterium carotovorum subsp. brasiliense subsp. nov

AIMS

Pectobacterium carotovorum is a heterogeneous species consisting of two named subspecies, P. carotovorum subsp. carotovorum and P. carotovorum subsp. odoriferum. A third subspecies, P. carotovorum subsp. brasiliense, was previously proposed. The study aimed to confirm the subspecies status and validate the proposed name of P. carotovorum subsp. brasiliense using a novel and standard microbial taxonomy.

METHODS AND RESULTS

DNA-DNA hybridization confirmed that P. carotovorum subsp. brasiliense is a different species from P. wasabiae, P. betavasculorum and P. atrosepticum, with 28, 35 and 55% similarity values, respectively, but is a member of the P. carotovorum species with 73-77% similarity values. Sequencing the entire 16S rRNA gene of two polymorphic copies from strains of each of the P. carotovorum subspecies demonstrated that the average 16S rRNA gene sequence diversity between P. carotovorum subsp. brasiliense and P. carotovorum subsp. carotovorum was lower than the maximum genetic distances between two sequence types obtained from the same strain. Multilocus sequence analysis based on eight housekeeping genes (mtlD, acnA, icdA, mdh, pgi, gabA, proA and rpoS) differentiated the subspecies and delineated two P. carotovorum subsp. brasiliense clades.

CONCLUSION

Pectobacterium carotovorum subsp. brasiliense clade I was comprised of strains isolated from Brazil and Peru, while clade II included strains from Asia, North America and Europe. Strains in clade I but not clade II were phenotypically consistent with the original description of P. carotovorum subsp. brasiliense in that they produced reducing substances from sucrose and acid from α-methyl glucoside. The type strain for P. carotovorum subsp. brasiliense 212(T) (= LMG2137(T) = IBSBF1692(T) = CFBP6617(T) ) was previously designated. The GC mol content of the type strain is 51·7%.

SIGNIFICANT AND IMPACT OF THE STUDY

the study introduces a full description for the strains belonging to the two different clades assigned to P. carotovorum subsp. brasiliense.

Case report: interaction of rifampin and nortriptyline

Rifampin is well documented to cause numerous clinically significant drug interactions because of its induction of the hepatic cytochrome P450 system. The metabolism of nortriptyline and other tricyclic antidepressants is induced and inhibited by this enzyme system. To the authors' knowledge, this is only the second case report in the literature regarding a possible interaction between rifampin and a tricyclic antidepressant. Nortriptyline serum concentrations were not detectable while rifampin was given concurrently. Two weeks after discontinuation of rifampin, nortriptyline concentrations increased dramatically. Further study of this possible interaction is warranted.