A systematic review of higher-risk myelodysplastic syndromes clinical trials to determine the benchmark of azacitidine and explore alternative endpoints for overall survival

The hypomethylating agent azacitidine can prolong overall survival (OS) in patients with higher risk-myelodysplastic syndromes (HR-MDS) compared to conventional regimens. However, outcomes differ largely between studies, making it challenging to determine the contribution of novel therapies added to azacitidine. Further, a discrepancy is seen between complete (CR) or partial (PR) response rates and OS improvement with azacitidine, making it challenging to rely on earlier endpoints than OS. We conducted a systematic literature search and study-level systematic review of 237 clinical studies to better understand outcomes for HR-MDS patients treated with azacitidine. Pooled marrow CR was 9% (N = 2654; 95% CI: 6-13 %), CR rate was 17 % (N = 6943; 95% CI: 15-20 %), and median OS (mOS) was 18.6 months (N = 2820; 95% CI: 15.3-21.9). A weak correlation to mOS was detected with CR rate (207 patient cohorts, Pearson\u27s r = 0.315; P \u3c 0.0005), and a much stronger correlation with median progression-free survival (mPFS) (r=0.88, P = 3 × 1

Moxetumomab pasudotox in heavily pre-treated patients with relapsed/refractory hairy cell leukemia (HCL): long-term follow-up from the pivotal trial

Background Moxetumomab pasudotox is a recombinant CD22-targeting immunotoxin. Here, we present the long-term follow-up analysis of the pivotal, multicenter, open-label trial (NCT01829711) of moxetumomab pasudotox in patients with relapsed/refractory (R/R) hairy cell leukemia (HCL). Methods Eligible patients had received ≥ 2 prior systemic therapies, including ≥ 2 purine nucleoside analogs (PNAs), or ≥ 1 PNA followed by rituximab or a BRAF inhibitor. Patients received 40 µg/kg moxetumomab pasudotox intravenously on Days 1, 3, and 5 of each 28-day cycle for up to six cycles. Disease response and minimal residual disease (MRD) status were determined by blinded independent central review. The primary endpoint was durable complete response (CR), defined as achieving CR with hematologic remission (HR, blood counts for CR) lasting > 180 days. Results Eighty adult patients were treated with moxetumomab pasudotox and 63% completed six cycles. Patients had received a median of three lines of prior systemic therapy; 49% were PNA-refractory, and 38% were unfit for PNA retreatment. At a median follow-up of 24.6 months, the durable CR rate (CR with HR > 180 days) was 36% (29 patients; 95% confidence interval: 26–48%); CR with HR ≥ 360 days was 33%, and overall CR was 41%. Twenty-seven complete responders (82%) were MRD-negative (34% of all patients). CR lasting ≥ 60 months was 61%, and the median progression-free survival without the loss of HR was 71.7 months. Hemolytic uremic and capillary leak syndromes were each reported in ≤ 10% of patients, and ≤ 5% had grade 3–4 events; these events were generally reversible. No treatment-related deaths were reported. Conclusions Moxetumomab pasudotox resulted in a high rate of durable responses and MRD negativity in heavily pre-treated patients with HCL, with a manageable safety profile. Thus, it represents a new and viable treatment option for patients with R/R HCL, who currently lack adequate therapy.publishedVersio

A phase 1/2 study of the oral FLT3 inhibitor pexidartinib in relapsed/refractory FLT3-ITD-mutant acute myeloid leukemia.

FMS-like tyrosine kinase 3 (FLT3) tyrosine kinase inhibitors (TKIs) have activity in acute myeloid leukemia (AML) patients with FLT3 internal tandem duplication (ITD) mutations, but efficacy is limited by resistance-conferring kinase domain mutations. This phase 1/2 study evaluated the safety, tolerability, and efficacy of the oral FLT3 inhibitor PLX3397 (pexidartinib), which has activity against the FLT3 TKI-resistant F691L gatekeeper mutation in relapsed/refractory FLT3-ITD-mutant AML. Ninety patients were treated: 34 in dose escalation (part 1) and 56 in dose expansion (part 2). Doses of 800 to 5000 mg per day in divided doses were tested. No maximally tolerated dose was reached. Plasma inhibitory assay demonstrated that patients dosed with ≥3000 mg had sufficient levels of active drug in their trough plasma samples to achieve 95% inhibition of FLT3 phosphorylation in an FLT3-ITD AML cell line. Based on a plateau in drug exposure, the 3000-mg dose was chosen as the recommended phase 2 dose. The most frequently reported treatment-emergent adverse events were diarrhea (50%), fatigue (47%), and nausea (46%). Based on modified response criteria, the overall response rate to pexidartinib among all patients was 21%. Twenty-three percent of patients treated at ≥2000 mg responded. The overall composite complete response rate for the study was 11%. Six patients were successfully bridged to transplantation. Median overall survival (OS) of patients treated in dose expansion was 112 days (90% confidence interval [CI], 77-150 days), and median OS of responders with complete remission with or without recovery of blood counts was 265 days (90% CI, 170-422 days). This trial was registered at www.clinicaltrials.gov as #NCT01349049

Oral azacitidine prolongs survival of patients with AML in remission independently of measurable residual disease status

Measurable residual disease (MRD) in patients with acute myeloid leukemia (AML) in remission after intensive chemotherapy is predictive of early relapse and poor survival. Postremission maintenance therapy that prolongs MRD negativity or converts MRD+ patients to MRD- status may delay or prevent relapse and improve overall survival (OS). In the phase 3 QUAZAR AML-001 trial, oral azacitidine (oral-AZA; formerly CC-486), a hypomethylating agent, significantly prolonged OS and relapse-free survival (RFS) compared with placebo in patients aged >= 55 years with AML in first remission after intensive chemotherapy who were not candidates for hematopoietic stem cell transplantation. In this trial, MRD (>= 0.1% leukemic cells in bone marrow) was assessed by multiparameter flow cytometry in serial samples collected at baseline and on day 1 of every 3 cycles. As expected, baseline MRD status was significantly associated with both OS and RFS. Multivariate analyses showed oral-AZA significantly improved OS and RFS vs placebo independent of baseline MRD status. Oral-AZA treatment also extended the duration of MRD negativity by 6 months vs placebo and resulted in a higher rate of conversion from MRD+ at baseline to MRD- during treatment: 37% vs 19%, respectively. In the oral-AZA arm, 24% of MRD responders achieved MRD negativity >6 months after treatment initiation. Although presence or absence of MRD was a strong prognostic indicator of OS and RFS, there were added survival benefits with oral-AZA maintenance therapy compared with placebo, independent of patients' MRD status at baseline.Peer reviewe

Oral arsenic trioxide ORH-2014 pharmacokinetic and safety profile in patients with advanced hematologic disorders

Daily intravenous arsenic trioxide administered with all-trans retinoid acid, the standard-of-care for acute promyelocytic leukemia, is costly and challenging to administer. ORH-2014 is a novel, oral arsenic trioxide formulation, consisting of micron-size drug particles with rapid dissolution and high bioavailability. We conducted a multicenter phase 1 dose-escalating study in patients with advanced hematologic malignancies. Twelve patients received ORH-2014 at 5 mg (n=3), 10 mg (n=6), or 15 mg (n=3) orally once a day (fasted state). Objectives were to assess the safety, tolerability and pharmacokinetics of ORH-2014 to support a dose recommendation for future trials. The median age of the patients was 77 years (range: 45-81) and they had received a median of two (range: 1-5) prior therapies. There were no dose limiting toxicities and no drug-related severe adverse events, except one grade III QT prolongation occurring beyond the dose limiting toxicity assessment period and resolving after treatment interruption. ORH-2014 steady-state plasma concentration was reached on day 15. ORH-2014, 15 mg Cmax was comparable to the calculated approved dose of intravenous arsenic trioxide (mean [% coefficient of variation]: 114 [21%] vs. 124 [60%] ng/mL) and area under the curve from 0 to 24 hours was 2,140 (36%) versus 1,302 (30%) h*ng/mL. These results indicate that ORH-2014 at 15 mg is safe, bioavailable, and provides the required arsenic exposure compared to intravenous arsenic trioxide at the approved dose (0.15 mg/kg); this ORH-2014 dose is recommended for future trials. (NCT03048344; www.clin-icaltrials.gov)

Targeted Therapy With the Mutant IDH2 Inhibitor Enasidenib for High-Risk IDH2-Mutant Myelodysplastic Syndrome

The isocitrate dehydrogenase enzyme 2 (IDH2) gene is mutated in ∼5% of patients with myelodysplastic syndrome (MDS). Enasidenib is an oral, selective, mutant IDH2 inhibitor approved for IDH2-mutated (mIDH2) relapsed/refractory acute myeloid leukemia. We designed a 2-arm multicenter study to evaluate safety and efficacy of (A) the combination of enasidenib with azacitidine for newly diagnosed mIDH2 MDS, and (B) enasidenib monotherapy for mIDH2 MDS after prior hypomethylating agent (HMA) therapy. Fifty patients with mIDH2 MDS enrolled: 27 in arm A and 23 in arm B. Median age of patients was 73 years. The most common adverse events were neutropenia (40%), nausea (36%), constipation (32%), and fatigue (26%). Hyperbilirubinemia from off-target UGT1A1 inhibition occurred in 14% of patients (8%; grades 3 and 4), and IDH-inhibitor-associated differentiation syndrome (IDH-DS) in 8 patients (16%). In the combination arm, the overall response rate (ORR: complete remission [CR] + marrow CR [mCR] + partial remission) was 74%, including 70% composite CR (CRc: CR + mCR). Median time to best response was 1 month (range, 1-4), and a median of 4 cycles was received (1-32). The median overall survival (OS) was 26 months (range, 14 to not reached). In the enasidenib monotherapy cohort after HMA failure, ORR and CRc were both 35% (n = 8), with 22% CR (n = 5). Median time to first response was 27 days, and time to best response was 4.6 months (2.7-7.6 months). A median of 7 cycles was received (range, 1-29), and the median OS was 20 months (range, 11 to not reached). Enasidenib is an effective treatment option for mIDH2 MDS, both in combination with azacitidine for treatment-naïve high-risk MDS, and as a single agent after prior HMA therapy. This trial is registered at www.clinicaltrials.gov as #NCT03383575

Toward a more patient‐centered drug development process in clinical trials for patients with myelodysplastic syndromes/neoplasms (MDS): Practical considerations from the International Consortium for MDS (icMDS)

Notable treatment advances have been made in recent years for patients with myelodysplastic syndromes/neoplasms (MDS), and several new drugs are under development. For example, the emerging availability of oral MDS therapies holds the promise of improving patients' health‐related quality of life (HRQoL). Within this rapidly evolving landscape, the inclusion of HRQoL and other patient‐reported outcomes (PROs) is critical to inform the benefit/risk assessment of new therapies or to assess whether patients live longer and better, for what will likely remain a largely incurable disease. We provide practical considerations to support investigators in generating high‐quality PRO data in future MDS trials. We first describe several challenges that are to be thoughtfully considered when designing an MDS‐focused clinical trial with a PRO endpoint. We then discuss aspects related to the design of the study, including PRO assessment strategies. We also discuss statistical approaches illustrating the potential value of time‐to‐event analyses and their implications within the estimand framework. Finally, based on a literature review of MDS randomized controlled trials with a PRO endpoint, we note the PRO items that deserve special attention when reporting future MDS trial results. We hope these practical considerations will facilitate the generation of rigorous PRO data that can robustly inform MDS patient care and support treatment decision‐making for this patient population

A phase 1b study of venetoclax and alvocidib in patients with relapsed/refractory acute myeloid leukemia

Relapsed/refractory (R/R) Acute Myeloid Leukemia (AML) is a genetically complex and heterogeneous disease with a poor prognosis and limited treatment options. Thus, there is an urgent need to develop therapeutic combinations to overcome drug resistance in AML. This open-label, multicenter, international, phase 1b study evaluated the safety, efficacy, and pharmacokinetics of venetoclax in combination with alvocidib in patients with R/R AML. Patients were treated with escalating doses of venetoclax (400, 600, and 800 mg QD, orally, days 1–28) and alvocidib (45 and 60 mg/m2, intravenously, days 1–3) in 28-day cycles. The combination was found to be safe and tolerable, with no maximum tolerated dose reached. Drug-related Grade ≥3 adverse events were reported in 23 (65.7%) for venetoclax and 24 (68.6%) for alvocidib. No drug-related AEs were fatal. Gastrointestinal toxicities, including diarrhea, nausea, and vomiting were notable and frequent; otherwise, the toxicities reported were consistent with the safety profile of both agents. The response rate was modest (complete remission [CR] + incomplete CR [CRi], 11.4%; CR + CRi + partial response rate + morphologic leukemia-free state, 20%). There was no change in alvocidib pharmacokinetics with increasing doses of venetoclax. However, when venetoclax was administered with alvocidib, AUC24 and Cmax decreased by 18% and 19%, respectively. A recommended phase 2 dose was not established due to lack of meaningful increase in efficacy across all cohorts compared to what was previously observed with each agent alone. Future studies could consider the role of the sequence, dosing, and the use of a more selective MCL1 inhibitor for the R/R AML population

Applicability and reproducibility of acute myeloid leukaemia stem cell assessment in a multi-centre setting

Leukaemic stem cells (LSC) have been experimentally defined as the leukaemia-propagating population and are thought to be the cellular reservoir of relapse in acute myeloid leukaemia (AML). Therefore, LSC measurements are warranted to facilitate accurate risk stratification. Previously, we published the composition of a one-tube flow cytometric assay, characterised by the presence of 13 important membrane markers for LSC detection