Complete Remission with Partial Hematological Recovery as a Palliative Endpoint for Treatment of Acute Myeloid Leukemia.

Complete remission with partial hematological recovery (CRh) has been used as an efficacy endpoint in clinical trials of nonmyelosuppressive drugs for acute myeloid leukemia (AML). We conducted a pooled analysis to characterize the clinical outcomes for patients with AML who achieved CRh after treatment with ivosidenib, olutasidenib, enasidenib, or gilteritinib monotherapy in clinical trials used to support marketing applications. The study cohort included 841 adult patients treated at the recommended drug dosage; 64.6% were red blood cell or platelet transfusion dependent at study baseline. Correlations between disease response and outcomes were assessed by logistic regression modeling for categorical variables and by Cox proportional hazards modeling for time-to-event variables. In comparison to patients with no response (NR), those with CRh had a higher proportion with transfusion independence (TI) for at least 56 days (92.3% vs 22.3%, p < 0.0001) or TI for at least 112 days (63.5% vs 8.7%, p < 0.0001), a reduced risk over time for severe infection (HR 0.43, p = 0.0007) or severe bleeding (HR 0.17, p = 0.01), and a longer overall survival (OS) (HR 0.31, p < 0.0001). The effects were consistent across drugs. In comparison to patients with CR, the effect sizes for CRh were similar for TI-56 and for risk over time of infection or bleeding but less for TI-112 and OS. CRh is associated with clinical benefits consistent with clinically meaningful palliative effects for treatment of AML with nonmyelosuppressive drugs, although less robustly than for CR.

FDA Approval Summary: Ivosidenib in Combination with Azacitidine for Treatment of Patients with Newly Diagnosed Acute Myeloid Leukemia with an IDH1 Mutation.

On May 25, 2022, FDA approved a supplemental application for ivosidenib (Tibsovo; Servier) extending the indication in patients with newly diagnosed IDH1-mutated acute myeloid leukemia (AML) in older adults or those with comorbidities to include the combination with azacitidine. The efficacy of ivosidenib in combination with azacitidine was evaluated in Study AG120-C-009, a phase 3, multicenter, double-blind, randomized (1:1), controlled study of ivosidenib or matched placebo in combination with azacitidine in adults with previously untreated AML with an IDH1 mutation who were 75 years or older or had comorbidities that precluded use of intensive induction chemotherapy. Efficacy was established on the basis of improved event-free survival and overall survival on the ivosidenib + azacitidine arm [HR, 0.35; 95% confidence interval (CI), 0.17-0.72; P = 0.0038, and HR, 0.44; 95% CI, 0.27-0.73; P = 0.0010], respectively. Furthermore, the rate and duration of complete remission (CR) were improved with ivosidenib versus placebo [CR 47% versus 15%, two-sided P < 0.0001; median duration of CR not estimable (NE; 95% CI, 13.0-NE) months versus 11.2 (95% CI, 3.2-NE) months. The safety profile of ivosidenib in combination with azacitidine was consistent with that of ivosidenib monotherapy, with important adverse reactions including differentiation syndrome (15%) and QT interval prolongation (20%).

Differentiation Syndrome in Acute Leukemia: APL and Beyond.

Differentiation syndrome (DS) is a frequent and potentially life-threatening clinical syndrome first recognized with the advent of targeted therapeutics for acute promyelocytic leukemia (APL). DS was subsequently observed more broadly with targeted therapeutics for acute myeloid leukemia (AML). DS is typically characterized by fever, dyspnea, hypotension, weight gain, pleural or pericardial effusions, and acute renal failure. The incidence in patients with APL ranges from 2 to 37%, with the wide variation likely attributed to different diagnostic criteria, use of prophylactic treatment, and different treatment regimens. Treatment with corticosteroids +/- cytoreductive therapy should commence as soon as DS is suspected to reduce DS-related morbidity and mortality. The targeted anti-leukemic therapy should be discontinued in patients with severe DS. Here, we discuss the pathogenesis of DS, clinical presentations, diagnostic criteria, management strategies, and implementation of prospective tracking on clinical trials.

Landscape and Regulatory Perspective on Oncology Drugs in Pregnancy.

Cancers affecting pregnant women include breast cancer, melanoma, thyroid cancer, cervical cancer, lymphomas, and leukemias. The medical management of cancer during pregnancy with molecularly targeted oncology drugs remains quite challenging, with knowledge gaps about the drugs' safety and efficacy due to exclusion of pregnant women from cancer clinical trials, discontinuation of individuals who become pregnant during clinical trials, and limited information on appropriate dosing of molecularly targeted oncology drugs during pregnancy. Physiological changes occur during pregnancy and may result in alterations in the absorption, distribution, metabolism, and excretion of drugs used in pregnant women. Physiologically based pharmacokinetic modeling that incorporates physiological changes induced by both the cancer disease state and pregnancy has the potential to inform dosing of molecularly targeted oncology drugs for pregnant women, improve our understanding of the pharmacokinetic changes associated with pregnancy in patients with cancer, facilitate the design of potential studies of molecularly targeted oncology drugs in pregnant women to support dosing recommendations, and provide model-informed pharmacokinetic data to support regulatory decision making.

FDA Analysis of Ineligibility for Acute Myeloid Leukemia Clinical Trials by Race and Ethnicity.

BACKGROUND: Patients of certain racial and ethnic groups have been underrepresented in clinical trials for treatment of malignancy. One potential barrier to participation is entry requirements that lead to patients in various racial and ethnic groups not meeting eligibility criteria for studies (ie, "screen failure"). The objective of this study was to analyze the rates and reasons for trial ineligibility by race and ethnicity in trials of acute myeloid leukemia (AML) submitted to the U.S. Food and Drug Administration (FDA) between 2016 and 2019. MATERIALS AND METHODS: Multicenter, global clinical trials submitted to the FDA to support AML drugs and biologics. We examined the rate of ineligibility among participants screened for studies of AML therapies submitted to the FDA from 2016 to 2019. Data were extracted from 13 trials used in approval evaluations, including race, screen status, and reason for ineligibility. RESULTS: Overall, patients in historically underrepresented racial and ethnic groups were less likely to meet entry criteria for studies compared to White patients, with 26.7% of White patients, 29.4% of Black patients, and 35.9% of Asian patients not meeting entry criteria. Lack of relevant disease mutation was the reason for ineligibility more frequently among Black and Asian patients. The findings were limited by the small number of underrepresented patients screened for participation. CONCLUSION: Our results suggest that entry requirements for studies may put underrepresented patients at a disadvantage, leading to less eligible patients and thus lower participation in clinical trials.

Considerations for Drug Development in Myelodysplastic Syndromes.

Myelodysplastic syndromes (MDS) have historically been challenging diseases for drug development due to their biology, preclinical modeling, and the affected patient population. In April 2022, the FDA convened a panel of regulators and academic experts in MDS to discuss approaches to improve MDS drug development. The panel reviewed challenges in MDS clinical trial design and endpoints and outlined considerations for future trial design in MDS to facilitate drug development to meaningfully meet patient needs. Challenges for defining clinical benefit in patients with MDS include cumbersome response criteria, standardized transfusion thresholds, and application and validation of patient reported outcome instruments. Clinical trials should reflect the biology of disease evolution, the advanced age of patients with MDS, and how patients are treated in real-world settings to maximize the likelihood of identifying active drugs. In patients with lower-risk disease, response criteria for anemic patients should be based on baseline transfusion dependency, improvement in symptoms, and quality of life. For higher-risk patients with MDS, trials should include guidance to prevent dose reductions or delays that could limit efficacy, specify minimal durations of treatment (in the absence of toxicity or progression), and have endpoints focused on overall survival and durable responses. MDS trials should be designed from the outset to allow the practicable application of new therapies in this high-needs population, with drugs that can be administered and tolerated in community settings, and with endpoints that meaningfully improve patients' lives over existing therapies.

Project Confirm: Accelerated Drug Approvals for Chronic Myeloid Leukemia.

The FDA has an accelerated approval program for drugs that have been identified as promising treatments for serious conditions when the available data suggest that the benefits outweigh the foreseeable risks. All of the currently available treatment options for chronic myeloid leukemia (CML) initially went through the accelerated approval program. Here, a group of academic CML experts, patient panelists, and members from the FDA convened to discuss the utility of the accelerated approval program as it pertains to CML, and the utility of this program in future drug development in this disease. The results of that discussion are summarized here.

FDA Approval Summary: Revised Indication and Dosing Regimen for Ponatinib Based on the Results of the OPTIC Trial.

On December 18, 2020, US Food and Drug Administration (FDA) approved a supplemental application for ponatinib extending the indication in patients with chronic-phase chronic myeloid leukemia (CP-CML) to patients with resistance or intolerance of at least 2 prior kinase inhibitors. Ponatinib was initially approved in December 2012 but was briefly voluntarily withdrawn due to serious safety concerns including the risk of arterial occlusive events (AOE). It returned to the market in December 2013 with an indication limited to patients with T315I mutation or for whom no other tyrosine kinase inhibitor (TKI) therapy was indicated with revised warnings and precautions. A post-marketing requirement was issued to identify the optimal safe and effective dose for CP-CML. Thus, the OPTIC trial was performed, which randomized patients to 1 of 3 doses, 45 mg, 30 mg, or 15 mg, with a dose reduction to 15 mg on achievement of MR2 (BCR-ABLIS ≤1%). Patients enrolled were treated with at least 2 prior TKIs or had a T315I mutation. Patients with a history of clinically significant, uncontrolled, or active cardiovascular disease were excluded. Efficacy was established on an interim analysis based on the rate of MR2 at 12 months in the modified intent-to-treat population of 261 patients, with 88, 86, and 87 patients in the 45, 30, and 15 mg cohorts, respectively. With a median follow-up of 28 months, the rate of achievement of MR2 at 12 months was 42%, 28%, and 24% in the respective cohorts. The safety profile was consistent with that observed in prior evaluations of ponatinib with notable adverse reactions including pancreatitis, hypertension, hyperlipidemia, liver dysfunction, and AOE. Of patients treated at the 45/15 mg dose, AOEs were seen in 13%, with a higher rate being observed in patients age 65 or older compared to younger patients. A readjudication of AOEs seen on the prior pivotal phase 2 study resulted in a rate of 26%. Overall, the results supported a modification of the recommended dose for patients with CP-CML to 45 mg until the achievement of MR2 followed by a reduction to 15 mg. The expansion of the indication to patients with exposure to 2 prior TKIs was approved given data showing that ponatinib could be successfully used for the treatment of this population with appropriate monitoring and screening for risk factors.

FDA Approval Summary: Decitabine and Cedazuridine Tablets for Myelodysplastic Syndromes.

On July 7, 2020, the Food and Drug Administration approved Inqovi (Otsuka Pharmaceutical Co.), an oral fixed-dose combination tablet comprising 35 mg decitabine, a hypomethylating agent, and 100 mg cedazuridine, a cytidine deaminase inhibitor (abbreviated DEC-C) for treatment of adult patients with myelodysplastic syndromes (MDS). Evidence of effectiveness of DEC-C was established in phase III ASTX727-02 (N = 133) in adults with MDS. The study involved a two-sequence crossover comparing DEC-C and intravenous (IV) decitabine 20 mg/m2 once daily for the first 5 days of each 28-day cycle in the first 2 cycles. From cycle 3 onward, patients received DEC-C. Five-day cumulative area under the curve (5-d AUC) of decitabine for DEC-C was similar to that of IV decitabine, with geometric mean ratio 0.99 (90% confidence interval: 0.93-1.06). Clinical benefit was supported by study ASTX727-02 and the similarly designed phase II study ASTX727-01-B (n = 80), with complete remission (CR) of 21% and 18% and median duration of CR 7.5 and 8.7 months, respectively. Adverse reactions were consistent with IV decitabine. Postmarketing assessments were issued to address the effect of cedazuridine on QT prolongation, food effect, moderate and severe hepatic impairment, and severe renal impairment on the pharmacokinetics and safety of DEC-C.

Meaningful response criteria for myelodysplastic syndromes.

Standardizing response criteria for myelodysplastic syndromes (MDS), a clinically and biologically heterogeneous group of disorders, has been historically challenging. The International Working Group (IWG) response criteria, first proposed in 2000 and modified in 2006 and 2018, represent the best effort by a group of international experts to define a set of clinically meaningful end-points in MDS. These criteria have been adopted in many MDS clinical trials, allowing for comparisons of response across trials. However, clinical experience has also revealed some limitations of these criteria, and most of the end-points proposed by the IWG require further validation. In this review, we present a critical analysis of the current MDS response criteria from both a practical standpoint and based on currently available clinical trial data. Potential areas for improvement in the criteria are highlighted, which may be considered in future iterations of the response criteria.

Project 2025: Proposals for the Continued Success of Drug Development in Acute Myeloid Leukemia.

The Food and Drug Administration Oncology Center of Excellence initiated Project 2025 to develop 5-year goals in specific areas of oncology drug development. This meeting, in October 2020, brought together a panel of regulators and academic experts in acute myeloid leukemia (AML) to discuss opportunities to maximize the success that has recently occurred in AML drug development. The panel discussed challenges and opportunities in clinical trial design and novel endpoints, and outlined key considerations for drug development to facilitate continued growth in the field.

Response Rate, Event-Free Survival, and Overall Survival in Newly Diagnosed Acute Myeloid Leukemia: US Food and Drug Administration Trial-Level and Patient-Level Analyses.

PURPOSE: To explore trial-level and patient-level associations between response (complete remission [CR] and CR + CR with incomplete hematologic [CRi] or platelet [CRp] recovery), event-free survival (EFS), and overall survival (OS) in newly diagnosed acute myeloid leukemia (AML) trials of intensive chemotherapy. METHODS: We identified data from eight randomized, active-controlled trials of intensive chemotherapy submitted to the US Food and Drug Administration for treatment of newly diagnosed AML (N = 4,482). Associations between trial-level odds ratios (ORs) for CR and CR + CRi or CRp, and hazard ratios (HRs) for EFS and OS were analyzed using weighted linear regression models. We performed patient-level responder analyses to compare OS by response using pooled data from all studies. RESULTS: In trial-level analyses, association between HR for OS and OR for CR was moderate (R2 = 0.49; 95% CI, 0.05 to 0.86), as was the association with OR for CR + CRi or CRp (R2 = 0.48; 95% CI, 0.05 to 0.99). For OS versus EFS, a strong association was observed (R2 = 0.87; 95% CI, 0.47 to 0.98) when EFS definitions were harmonized across trials using raw data. In the patient-level responder analyses, patients who achieved CR had better OS compared with CRi or CRp responders (0.73; 95% CI, 0.64 to 0.84) and nonresponders (HR, 0.33; 95% CI, 0.31 to 0.37). CONCLUSION: On a trial level, there is a moderate association between OS and CR rate. A strong association between EFS and OS was observed. However, CIs were wide, and results became moderate using alternative definitions for EFS. Patient-level analyses showed CR responders have better OS compared with CRi or CRp responders and nonresponders. A therapy in newly diagnosed AML with benefit in EFS or substantial benefit in CR rate would be likely to have an OS effect.

FLT3-ITD Allelic Burden and Acute Promyelocytic Leukemia Risk Stratification.

The significance of FLT3-ITD in acute promyelocytic leukemia (APL) is not well-established. We performed a bi-center retrospective study of 138 APL patients, 59 (42.8%) of whom had FLT3-ITD. APL patients with FLT3-ITD had higher baseline white blood cell counts (WBCs) (p < 0.001), higher hemoglobin, (p = 0.03), higher aspartate aminotransferase (p = 0.001), lower platelets (p = 0.004), lower fibrinogen (p = 0.003), and higher incidences of disseminated intravascular coagulation (p = 0.005), M3v variant morphology (p < 0.001), and the bcr3 isoform (p < 0.001). FLT3-ITD was associated with inferior post-consolidation complete remission (CR) (p = 0.02) and 5-year overall survival (OS) of 79.7%, compared to 94.4% for FLT3-WT (wild-type) (p = 0.02). FLT3-ITD was strongly associated with baseline WBCs ≥ 25 × 109/L (odds ratio (OR): 54.4; 95% CI: 10.4-286.1; p < 0.001). High FLT3-ITD allelic burdens correlated with high-risk (HR) Sanz scores and high WBCs, with every 1% increase in allelic burden corresponding to a 0.6 × 109/L increase in WBC. HR APL was associated with a 38.5% increase in allelic burden compared with low-risk (LR) APL (95% CI: 19.8-57.2; p < 0.001). Our results provide additional evidence that FLT3-ITD APL is a distinct subtype of APL that warrants further study to delineate potential differences in therapeutic approach.

Increased body mass index is a risk factor for acute promyelocytic leukemia.

Introduction: Obesity has become increasingly prevalent worldwide and is a risk factor for many malignancies. We studied the correlation between body mass index (BMI) and the incidence of acute promyelocytic leukemia (APL), non-APL acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), and control hospitalized patients without leukemia in the same community. Methods: Multi-center, retrospective analysis of 71,196 patients: APL (n=200), AML (n=437), ALL (n=103), non-leukemia hospitalized (n=70,456) admitted to University of Maryland and Johns Hopkins Cancer Centers, and University of Maryland Medical Center. Results: Patients with APL had a significantly higher unadjusted mean and median BMI (32.5 kg/m2 and 30.3 kg/m2) than those with AML (28.3 kg/m2 and 27.1 kg/m2), ALL (29.3 kg/m2 and 27.7 kg/m2), and others (29.3 kg/m2 and 27.7 kg/m2) (p<0.001). Log-transformed BMI multivariable models demonstrated that APL patients had a significantly higher adjusted mean BMI by 3.7 kg/m2 (p<0.001) or approximately 10% (p<0.01) compared to the other groups, when controlled for sex, race, and age. Conclusions: This study confirms that when controlled for sex, age, and race there is an independent association of higher BMI among patients with APL compared to patients with ALL, AML, and hospitalized individuals without leukemia in the same community.

FDA Approval Summary: Gilteritinib for Relapsed or Refractory Acute Myeloid Leukemia with a FLT3 Mutation.

On November 28, 2018, the FDA approved gilteritinib (Xospata; Astellas), a small-molecule FMS-like tyrosine kinase 3 (FLT3) inhibitor, for treatment of relapsed or refractory acute myeloid leukemia with a FLT3 mutation as detected by an FDA-approved test. In the ADMIRAL study, patients were randomized 2:1 to receive gilteritinib or standard chemotherapy and stratified by response to first-line treatment and intensity of prespecified chemotherapy. Efficacy was established on interim analysis on the basis of complete remission (CR) + CR with partial hematologic recovery (CRh) rate, duration of CR + CRh, and conversion from transfusion dependence to transfusion independence in 138 patients in the gilteritinib arm. With median follow-up of 4.6 months [95% confidence interval (CI), 2.8-15.8 months] at interim analysis, the CR + CRh rate was 21% (95% CI, 15%-29%), median duration of CR + CRh was 4.6 months (range, 0.1-15.8+), and conversion from transfusion dependence to transfusion independence was 31%. Revised labeling approved on May 29, 2019 included the results of the final analysis, showing an improvement in overall survival (OS) with gilteritinib compared with chemotherapy (HR, 0.64; 95% CI, 0.49-0.83; one-sided P = 0.0004; median OS, 9.3 vs. 5.6 months). The OS benefit was observed in both high and low chemotherapy intensity subgroups. Labeling includes a boxed warning for differentiation syndrome and warnings for posterior reversible encephalopathy syndrome, QT prolongation, pancreatitis, and embryo-fetal toxicity. Safe use requires frequent monitoring of electrocardiograms and blood chemistries. Assessments of long-term safety are pending.

Differentiation Syndrome with Ivosidenib and Enasidenib Treatment in Patients with Relapsed or Refractory IDH-Mutated AML: A U.S. Food and Drug Administration Systematic Analysis.

PURPOSE: Differentiation syndrome (DS) is a serious adverse reaction of isocitrate dehydrogenase (IDH) inhibitors ivosidenib and enasidenib in patients with (IDH)1- and IDH2-mutated acute myeloid leukemia (AML), respectively. EXPERIMENTAL DESIGN: During FDA review of marketing applications for ivosidenib and enasidenib, data from pivotal trials were queried to identify cases of DS in patients with relapsed or refractory (R/R) AML. One hundred seventy-nine patients with R/R AML received ivosidenib and 214 received enasidenib. Adverse events, labs, and vital signs in the first 90 days of treatment were screened per diagnostic criteria, and narratives were reviewed to adjudicate DS cases. RESULTS: We identified 72 of 179 (40%) potential cases for ivosidenib and 86 of 214 (40%) for enasidenib; 34 of 179 (19%) and 41 of 214 (19%) were adjudicated as DS. Leukocytosis was present in 79% and 61% of cases, respectively. Median (range) time to onset was 20 (1-78) and 19 (1-86) days. Grade ≥ 3 adverse reactions occurred in 68% and 66%; 6% and 5% were fatal. Univariate analyses suggested baseline bone marrow blasts ≥ 48% and peripheral blood blasts ≥ 25% and 15% for ivosidenib and enasidenib, respectively, were associated with increased risk of DS. Complete remission (CR) + CR with partial hematologic recovery rates were lower in patients with versus without DS [ivosidenib 18% (95% confidence interval, 7%-35%) vs. 36% (28%-45%); enasidenib 18% (7%-33%) vs. 25% (18%-32%)]. CONCLUSIONS: DS is a common and potentially fatal adverse reaction of IDH inhibitors, and use of standardized diagnostic criteria may aid in earlier diagnosis and treatment.See related commentary by Zeidner, p. 4174.