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: Brexucabtagene Autoleucel for Treatment of Adults With Relapsed or Refractory B-Cell Precursor Acute Lymphoblastic Leukemia.

In October 2021, the FDA approved brexucabtagene autoleucel (brexu-cel), a CD19-directed chimeric antigen receptor (CAR) T-cell therapy, for the treatment of adult patients with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (B-ALL). Approval was based on the phase II portion of ZUMA-3, a single-arm, open-label, multicenter trial that evaluated a single infusion of brexu-cel, preceded by lymphodepleting chemotherapy with cyclophosphamide and fludarabine, in this population. Efficacy was established on the basis of complete remission (CR) within 3 months after infusion and the duration of CR (DOCR). Among 54 patients in the efficacy analysis population, the CR rate was 52% (95% CI: 38, 66) with a median time-to-response of 56 days. With a median follow-up for responders of 7.1 months, the median DOCR was not reached. For all leukapheresed patients in the phase II portion of this trial (n = 71), the CR rate was 41% (95% CI: 29, 53). Among the 78 patients treated with the approved dose of brexu-cel, serious adverse reactions occurred in 79% and fatal adverse reactions occurred in 5% and included cerebral edema and infections. Cytokine release syndrome occurred in 92% (grade ≥3, 26%) and neurologic toxicities occurred in 87% (grade ≥3, 35%), leading to implementation of a risk evaluation and mitigation strategy (REMS). Postmarketing study with 15 years of follow-up will further evaluate long-term safety in adult patients with relapsed or refractory B-ALL.

FDA Approval Summary: Ruxolitinib for Treatment of Chronic Graft-Versus-Host Disease after Failure of One or Two Lines of Systemic Therapy.

On September 22, 2021, the Food and Drug Administration approved ruxolitinib for the treatment of chronic graft-versus-host disease (cGVHD) after the failure of one or two lines of systemic therapy in adult and pediatric patients 12 years and older. Approval was based on Study INCB 18424-365 (REACH-3; CINC424D2301; NCT03112603), a randomized, open-label, multicenter trial of ruxolitinib in comparison to best available therapy (BAT) for the treatment of corticosteroid-refractory cGVHD occurring after the allogeneic hematopoietic stem cell transplantation. A total of 329 patients were randomized 1:1 to receive either ruxolitinib 10 mg twice daily (n = 165) or BAT (n = 164). BAT was selected by the investigator prior to randomization. The overall response rate through Cycle 7 Day 1 was 70% (95% CI, 63-77) in the ruxolitinib arm, and 57% (95% CI, 49-65) in the BAT arm. The median duration of response, calculated from first response to progression, death, or initiation of new systemic therapies for cGVHD, was 4.2 months (95% CI, 3.2-6.7) for the ruxolitinib arm and 2.1 months (95% CI, 1.6-3.2) for the BAT arm; and the median time from first response to death or initiation of new systemic therapies for cGVHD was 25 months (95% CI, 16.8-not estimable) for the ruxolitinib arm and 5.6 months (95% CI, 4.1-7.8) for the BAT arm. Common adverse reactions included anemia, thrombocytopenia, and infections. Given the observed response rate with durability, the clinical benefit of ruxolitinib appears to outweigh the risks of treatment for cGVHD after the failure of one or two lines of systemic therapy.

FDA Approval Summary: Oral Azacitidine for Continued Treatment of Adults with Acute Myeloid Leukemia Unable to Complete Intensive Curative Therapy.

On September 1, 2020, the FDA granted approval for oral azacitidine (Onureg, CC-486) for continued treatment of adult patients with acute myeloid leukemia (AML) who achieved complete remission (CR) or complete remission with incomplete blood count recovery (CRi) following intensive induction chemotherapy and who are not able to complete intensive curative therapy. Approval was based on improvement in overall survival using CC-486 300 mg daily in a 2 weeks on/2 weeks off schedule in comparison with placebo (HR, 0.69; 95% confidence interval, 0.55-0.86; P = 0.0009) in the randomized trial CC-486-AML-001 (QUAZAR) in adults ≥ 55 years old with AML in CR/CRi who did not complete standard intensive induction and postremission therapy. Of note, the study was not designed to test CC-486 as maintenance after standard postremission therapy or as an alternative to standard postremission therapy. Gastrointestinal toxicities, fatigue, and pneumonia were more common in patients treated with CC-486 compared with placebo. Additional studies are needed to establish safe dosing for patients with hepatic impairment. The pharmacokinetic parameters, recommended dose, and recommended schedule of CC-486 differ substantially from those of other azacitidine formulations; therefore, inappropriate substitutions between formulations pose a considerable risk for harm.

FDA Approval Summary: Belumosudil for Adult and Pediatric Patients 12 Years and Older with Chronic GvHD after Two or More Prior Lines of Systemic Therapy.

On July 16, 2021, the FDA approved belumosudil, a kinase inhibitor, for adult and pediatric patients 12 years and older with chronic GvHD (cGvHD) after failure of at least two prior lines of systemic therapy. Approval was based on the results of Study KD025-213, which included 65 patients with cGvHD treated with belumosudil 200 mg daily in an open-label, single-arm cohort. Efficacy was determined by the overall response rate (ORR) through Cycle 7 Day 1, which included complete response (CR) or partial response (PR) according to the 2014 NIH consensus criteria, and durability of response. The ORR through Cycle 7 Day 1 was 75% [95% confidence interval (CI), 63-85]; 6% of patients achieved a CR, and 69% achieved a PR. The median duration of response was 1.9 months (95% CI, 1.2-2.9), and 62% (95% CI, 46-74) of responding patients remained alive without new systemic therapy for at least 12 months from response. The common adverse reactions were infections, asthenia, nausea, diarrhea, dyspnea, cough, edema, hemorrhage, abdominal pain, musculoskeletal pain, headache, phosphate decreased, gamma-glutamyl transferase increased, lymphocytes decreased, and hypertension. Additional study is warranted to confirm safety with long-term use.

Using marginal structural models to analyze the impact of subsequent therapy on the treatment effect in survival data: Simulations and clinical trial examples.

We explore the impact of time-varying subsequent therapy on the statistical power and treatment effects in survival analysis. The marginal structural model (MSM) with stabilized inverse probability treatment weights (sIPTW) was used to account for the effects due to the subsequent therapy. Simulations were performed to compare the MSM-sIPTW method with the conventional method without accounting for the time-varying covariate such as subsequent therapy that is dependent on the initial response of the treatment effect. The results of the simulations indicated that the statistical power, thereby the Type I error, of the trials to detect the frontline treatment effect could be inflated if no appropriate adjustment was made for the impact due to the add-on effects of the subsequent therapy. Correspondingly, the hazard ratio between the treatment groups may be overestimated by the conventional analysis methods. In contrast, MSM-sIPTW can maintain the Type I error rate and gave unbiased estimates of the hazard ratio for the treatment. Two real examples were used to discuss the potential clinical implications. The study demonstrated the importance of accounting for time-varying subsequent therapy for obtaining unbiased interpretation of data.

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.

Weighty choices: selecting optimal G-CSF doses for stem cell mobilization to optimize yield.

There are limited data on the effect of donor body mass index (BMI) on peripheral blood stem cell (PBSC) mobilization response to granulocyte colony-stimulating factor (G-CSF), especially in unrelated donors. Obesity has been associated with persistent leukocytosis, elevated circulating progenitor cells, and enhanced stem cell mobilization. Therefore, we hypothesized that adequate collection of CD34+ cells may be achieved with lower doses (per kilogram of body weight) of G-CSF in donors with higher BMI compared with donors with lower BMI. Using the Center for International Blood and Marrow Transplant Research database, we evaluated the impact of donor BMI on G-CSF-mobilized PBSC yield in healthy unrelated donors. We examined 20 884 PBSC donations collected at National Marrow Donor Program centers between 2006 and 2016. We found significantly higher collection yields in obese and severely obese donors compared with normal and overweight donors. An increase in average daily G-CSF dose was associated with an increase in stem cell yield in donors with normal or overweight BMI. In contrast, an increase in average daily G-CSF dose beyond 780 µg per day in obese and 900 µg per day in severely obese donors did not increase cell yield. Pain and toxicities were assessed at baseline, during G-CSF administration, and postcollection. Obesity was associated with higher levels of self-reported donation-related pain and toxicities in the pericollection and early postdonation recovery periods. This study suggests a maximum effective G-CSF dose for PBSC mobilization in obese and severely obese donors, beyond which higher doses of G-CSF add no increased yield.

FDA Approval Summary: Ruxolitinib for Treatment of Steroid-Refractory Acute Graft-Versus-Host Disease.

On May 24, 2019, the Food and Drug Administration approved ruxolitinib for steroid-refractory acute graft-versus-host disease (SR-aGVHD) in adult and pediatric patients 12 years and older. Approval was based on Study INCB 18424-271 (REACH-1; NCT02953678), an open-label, single-arm, multicenter trial that included 49 patients with grades 2-4 SR-aGVHD occurring after allogeneic hematopoietic stem cell transplantation. Ruxolitinib was administered at 5 mg twice daily, with dose increases to 10 mg twice daily permitted after 3 days in the absence of toxicity. The Day-28 overall response rate was 57.1% (95% confidence interval [CI]: 42.2-71.2). The median duration of response was 0.5 months (95% CI: 0.3-2.7), and the median time from Day-28 response to either death or need for new therapy for acute GVHD was 5.7 months (95% CI: 2.2 to not estimable). Common adverse reactions included anemia, thrombocytopenia, neutropenia, infections, edema, bleeding, and elevated transaminases. Ruxolitinib is the first drug approved for treatment of SR-aGVHD. IMPLICATIONS FOR PRACTICE: Ruxolitinib is the first Food and Drug Administration-approved treatment for steroid-refractory acute graft-versus-host disease in adult and pediatric patients 12 years and older. Its approval provides a treatment option for the 60% of those patients who do not respond to steroid therapy.

FDA Approval Summary: Tagraxofusp-erzs For Treatment of Blastic Plasmacytoid Dendritic Cell Neoplasm.

Tagraxofusp-erzs (Elzonris, Stemline) is a cytotoxin that targets CD123-expressing cells. On December 21, 2018, FDA approved tagraxofusp-erzs for the treatment of blastic plasmacytoid dendritic cell neoplasms (BPDCN) in adult and pediatric patients 2 years and older. Approval was based on the response rate in a single-arm trial, Study STML-401-0114; the pivotal cohort included 13 patients with treatment-naïve BPDCN who received tagraxofusp-erzs monotherapy. The complete response or clinical complete response (CR/CRc) rate in the pivotal cohort was 54% (95% CI: 25%-81%), and the median duration of CR/CRc was not reached with a median follow-up of 11.5 months (range: 0.2-12.7). In a separate exploratory cohort, a CR/CRc was achieved by 2 (13%) patients with R/R BPDCN. Safety was assessed in 94 patients with myeloid neoplasms treated with tagraxofusp-erzs at the approved dose and schedule. The major toxicity was capillary leak syndrome (CLS), which occurred in 55% of patients and was fatal in 2%. Hepatotoxicity and hypersensitivity reactions were reported in 88% and 46% of patients, respectively. Other common (≥30%) adverse reactions were nausea, fatigue, peripheral edema, pyrexia, and weight increase. A high proportion of patients (85%) developed neutralizing antidrug antibodies. Tagraxofusp-erzs is the first FDA-approved treatment for BPDCN.

FDA Approval Summary: Calaspargase Pegol-mknl For Treatment of Acute Lymphoblastic Leukemia in Children and Young Adults.

On December 20, 2018, the Food and Drug Administration approved calaspargase pegol-mknl (CALASP), an asparagine-specific enzyme, as a component of a multi-agent chemotherapeutic regimen for acute lymphoblastic leukemia (ALL) in pediatric and young adult patients age 1 month to 21 years. Efficacy was determined on the basis of achievement and maintenance of steady-state nadir serum asparaginase activity (NSAA) above 0.1 U/mL when using CALASP, 2,500 U/m2 intravenously, every 3 weeks. In a randomized comparison to pegaspargase (PEGASP) every 2 weeks, treatment with CALASP every 3 weeks had a similar safety profile and no substantial impairment in event-free survival. The pharmacokinetics of CALASP were studied when administered in combination with multiagent chemotherapy in 124 patients with B-cell ALL in Study AALL07P4 and Study DFCI 11-001. The results showed that 123 [99%, 95% confidence interval (CI), 96%-100%] of the 124 patients maintained NSAA >0.1 U/mL at weeks 6, 12, 18, 24, and 30 of post-induction phase. Maintaining adequate NSAA levels is critical to successful treatment of ALL. Herein, we describe the FDA review and approval of CALASP.See related commentary by Lew, p. 325.

Idelalisib for Treatment of Relapsed Follicular Lymphoma and Chronic Lymphocytic Leukemia: A Comparison of Treatment Outcomes in Clinical Trial Participants vs Medicare Beneficiaries.

Importance: Idelalisib (IDEL) is approved as monotherapy in relapsed follicular lymphoma (FL) and with rituximab (IDEL+R) for relapsed chronic lymphocytic leukemia (CLL). Toxic effects can be severe and treatment-limiting. Outcomes in a real-world population are not yet characterized. Objective: We compared IDEL treatment outcomes in the clinical setting with outcomes in clinical trial data. Design, Setting, and Participants: This cohort study compared clinical trial participants treated with IDEL, aged 65 years or older, in studies 101-09 and 312-0116 with Medicare beneficiaries treated with IDEL of the same disease state and treatment regimen. Study 101-09 was a phase 2, single-group, open-label trial supporting accelerated approval of IDEL for relapsed or refractory FL. Study 312-0116 was a phase 3, multicenter, randomized, double-blind trial supporting approval of IDEL+R for relapsed CLL. Analyses were conducted between February and December 2018. Main Outcomes and Measures: Treatment duration, on-treatment and overall mortality, and serious and fatal infections were compared between trial participants and Medicare beneficiaries. Cox proportional hazards models quantified differences by cohort. Results: We identified 26 trial participants (mean [SD] age, 73 [4.9] years; 12 [46.2%] women) and 305 Medicare beneficiaries (mean [SD] age, 76 [6.9] years; 103 [54.8%] women) receiving IDEL for FL and 89 trial participants (mean [SD] age, 74 [6.0] years; 30 [33.7%] women) and 294 Medicare beneficiaries (mean age, 76 [6.3] years; 111 [37.8%] women) receiving IDEL+R for CLL. Medicare beneficiaries were older with higher comorbidity; had a shorter median treatment duration for CLL (173 days vs 473 days, P < .001) but not FL (114, days vs 160 days, P = .38); a numerically higher mortality rate (CLL: HR, 1.40; 95% CI, 0.93-2.11; FL: HR, 1.39; 95% CI, 0.69-2.78); and a significantly higher fatal infection rate per 100 person-years for CLL (18.4 vs 9.8, P = .04) and a numerically higher rate for FL (27.6 vs 18.6, P = .54), compared with trial participants. Trial participants had approximately twice as many dose reductions (CLL: 32.6% vs 18.0%; P = .003; FL: 38.5% vs 16.1%; P = .02). Among Medicare beneficiaries, a hospitalized infection within 6 months prior to IDEL initiation was associated with a 2.11-fold increased risk for on-treatment fatal infections (95% CI, 1.44-3.10). Despite a March 2016 recommendation for Pneumocystis jirovecii pneumonia prophylaxis in patients treated with IDEL, prophylaxis rates were low after March 2016 (FL: 25%, CLL: 37%). Conclusions and Relevance: We observed substantial imbalances in baseline comorbidities and treatment outcomes between Medicare beneficiaries and trial participants aged 65 years or older. Immunosuppression-related toxic effects, including infections, may have been somewhat reduced in trials by more frequent dose reductions and exclusion of patients with ongoing infections. Selective eligibility criteria and closer monitoring of trial patients may be responsible for limited generalizability of trial data to clinical practice.

FDA Approval Summary: Glasdegib for Newly Diagnosed Acute Myeloid Leukemia.

On November 21, 2018, the FDA approved glasdegib (Daurismo; Pfizer), a small-molecule Hedgehog inhibitor, in combination with low-dose cytarabine (LDAC) for treatment of newly diagnosed acute myeloid leukemia (AML) in adults ≥ 75 years or with comorbidities that preclude use of intensive induction chemotherapy. Evidence of clinical benefit came from Study BRIGHT AML 1003, a randomized trial comparing glasdegib+LDAC with LDAC alone for treatment of newly diagnosed AML in 115 patients either ≥ 75 years old or ≥ 55 years old with preexisting comorbidities. Efficacy was established by improved overall survival (OS) with the combination compared with LDAC alone (HR, 0.46; 95% confidence interval, 0.30-0.71; one-sided stratified log-rank P = 0.0002). Median OS was 8.3 months with the combination and 4.3 months with LDAC alone. Common adverse reactions included cytopenias, fatigue, hemorrhage, febrile neutropenia, musculoskeletal pain, nausea, edema, dyspnea, decreased appetite, dysgeusia, mucositis, constipation, and rash. The label includes a boxed warning for embryo-fetal toxicity and a warning for QT interval prolongation. There is a limitation of use for patients with moderate-to-severe hepatic and severe renal impairment; trials studying glasdegib in these patient populations are required as a condition of this approval.See related commentary by Fathi, p. 6015.

FDA Approval Summary: Ivosidenib for Relapsed or Refractory Acute Myeloid Leukemia with an Isocitrate Dehydrogenase-1 Mutation.

The FDA approved ivosidenib (Tibsovo; Agios), a small-molecule inhibitor of isocitrate dehydrogenase (IDH)1 on July 20, 2018, for treatment of adults with relapsed or refractory acute myeloid leukemia (R/R AML) with susceptible IDH1 mutation as detected by an FDA-approved test. The efficacy of ivosidenib was established on the basis of complete remission (CR) + CR with partial hematologic recovery (CRh) rate, duration of CR + CRh, and conversion from transfusion dependence (TD) to transfusion independence (TI) in Study AG120-C-001, a single-arm trial. With median follow-up of 8.3 months for 174 adults with IDH1-mutated R/R AML treated with 500 mg ivosidenib daily, the CR + CRh rate was 33% [95% confidence interval (CI), 26-40], median duration of response was 8.2 (95% CI, 5.6-12) months, and conversion from TD to TI occurred in 37% of patients. These endpoints reflect short-term benefit in patients with an unmet medical need; long-term efficacy outcomes were not assessed. Serious adverse reactions (AR) in ≥5% of patients were differentiation syndrome (10%), leukocytosis (10%), and QT interval prolongation (7%). Common (≥20%) ARs of any grade were fatigue, leukocytosis, arthralgia, diarrhea, dyspnea, edema, nausea, mucositis, QT interval prolongation, rash, pyrexia, cough, and constipation. Assessment of long-term safety of ivosidenib is a condition of this approval.

FDA Approval Summary: Tisagenlecleucel for Treatment of Patients with Relapsed or Refractory B-cell Precursor Acute Lymphoblastic Leukemia.

Tisagenlecleucel (Kymriah; Novartis Pharmaceuticals) is a CD19-directed genetically modified autologous T-cell immunotherapy. On August 30, 2017, the FDA approved tisagenlecleucel for treatment of patients up to 25 years of age with B-cell precursor acute lymphoblastic leukemia (ALL) that is refractory in second or later relapse. Approval was based on the complete remission (CR) rate, durability of CR, and minimal residual disease (MRD) <0.01% in a cohort of 63 children and young adults with relapsed or refractory ALL treated on a single-arm trial (CCTL019B2202). Treatment consisted of fludarabine and cyclophosphamide followed 2 to 14 days later by a single dose of tisagenlecleucel. The CR rate was 63% (95% confidence interval, 50%-75%), and all CRs had MRD <0.01%. With a median follow-up of 4.8 months, the median duration of response was not reached. Cytokine release syndrome (79%) and neurologic events (65%) were serious toxicities reported in the trial. With implementation of a Risk Evaluation and Mitigation Strategy, the benefit-risk profile was considered acceptable for this patient population with such resistant ALL. A study of safety with 15 years of follow-up is required as a condition of the approval.See related commentary by Geyer, p. 1133.

FDA Approval: Blinatumomab for Patients with B-cell Precursor Acute Lymphoblastic Leukemia in Morphologic Remission with Minimal Residual Disease.

On March 29, 2018, the FDA granted accelerated approval for blinatumomab (Blincyto; Amgen, Inc.) for the treatment of adults and children with B-cell precursor acute lymphoblastic leukemia (BCP ALL) in first or second complete remission with minimal residual disease (MRD) greater than or equal to 0.1%. Blinatumomab is a CD3xCD19 bispecific antibody approved previously for the treatment of relapsed or refractory BCP ALL. The basis for this accelerated approval was a single-arm trial. For the 86 patients in first and second complete remission with MRD ≥ 0.1%, conversion to MRD < 0.01% was achieved after one cycle of blinatumomab by 85.2% [95% confidence interval (CI): 73.8%, 93.0%] and 72.0% (95% CI: 50.6%, 87.9%), respectively, and the estimated median hematologic relapse-free survivals (RFS) were 35.2 months (95% CI: 0.4-53.5) and 12.3 months (95% CI: 0.7-42.3), respectively. Hematologic RFS was considered substantial independent of whether patients underwent subsequent allogeneic stem cell transplantation. The safety profile for blinatumomab was established in prior studies, and no new safety signals were observed in the new population. Cytokine release syndrome and neurotoxicity remain significant risks. The FDA is requiring confirmation of clinical benefit in a randomized trial.

FDA Approval Summary: (Daunorubicin and Cytarabine) Liposome for Injection for the Treatment of Adults with High-Risk Acute Myeloid Leukemia.

On August 3, 2017, the FDA granted regular approval to Vyxeos (also known as CPX-351; Jazz Pharmaceuticals), a liposomal formulation of daunorubicin and cytarabine in a fixed combination, for the treatment of adults with newly diagnosed therapy-related acute myeloid leukemia (t-AML) or acute myeloid leukemia (AML) with myelodysplasia-related changes (AML-MRC). Approval was based on data from Study CLTR0310-301, a randomized, multicenter, open-label, active-controlled trial comparing Vyxeos with a standard combination of daunorubicin and cytarabine ("7+3") in 309 patients 60-75 years of age with newly diagnosed t-AML or AML-MRC. Because of elemental copper concerns with the Vyxeos formulation, patients with Wilson disease were excluded from the study. Vyxeos demonstrated an improvement in overall survival (HR 0.69; 95% confidence interval, 0.52-0.90; P = 0.005) with an estimated median overall survival of 9.6 months compared with 5.9 months for the "7+3" control arm. The toxicity profile of Vyxeos was similar to that seen with standard "7+3" with the exception of more prolonged neutropenia and thrombocytopenia on the Vyxeos arm. Because the pharmacology of Vyxeos differs from that of other formulations of daunorubicin and cytarabine, labeling includes a warning against interchanging formulations during treatment. This is the first FDA-approved treatment specifically for patients with t-AML or AML-MRC.

FDA Approval Summary: Midostaurin for the Treatment of Advanced Systemic Mastocytosis.

In April 2017, the U.S. Food and Drug Administration granted regular approval to midostaurin for the treatment of adult patients with aggressive systemic mastocytosis (ASM), systemic mastocytosis with associated hematological neoplasm (SM-AHN), or mast cell leukemia (MCL). Approval was based on results from CPKC412D2201, a single-arm trial of midostaurin (100 mg orally twice daily) in previously treated or untreated patients. For the patients with ASM and SM-AHN, efficacy was established on the basis of confirmed complete remission (CR) plus incomplete remission (ICR) by modified Valent criteria with six cycles of midostaurin. There were no CRs reported; ICR was achieved by 6 of 16 patients (38%; 95% confidence interval [CI]: 15%-65%) with ASM and by 9 of 57 patients (16%; 95% CI: 7%-28%) with SM-AHN. Within the follow-up period, the median duration of response was not reached for the patients with ASM (range, 12.1+ to 36.8+ months) or with SM-AHN (range, 6.6+ to 52.1+ months). For the patients with MCL, efficacy was established on the basis of confirmed CR using modified 2013 International Working Group-Myeloproliferative Neoplasms Research and Treatment-European Competence Network on Mastocytosis criteria. Of 21 patients with MCL, 1 (5%) achieved a CR. Of 142 patients with SM evaluated for safety, 56% had dose modifications for toxicity, and 21% discontinued treatment due to a toxicity. Over 50% reported nausea, vomiting, or diarrhea, and ≥30% reported edema, musculoskeletal pain, fatigue, abdominal pain, or upper respiratory tract infection. New or worsening grade ≥3 lymphopenia, anemia, thrombocytopenia, or neutropenia developed in ≥20%. Although midostaurin is an active drug for treatment of advanced SM, it is not clear that the optimal dose has been identified. IMPLICATIONS FOR PRACTICE: Midostaurin is the only U.S. Food and Drug Administration-approved therapy for patients with systemic mastocytosis with associated hematological neoplasm and mast cell leukemia and is the only therapy approved for patients with aggressive systemic mastocytosis regardless of KIT D816V mutation status. Based on response rate and duration, midostaurin has meaningful clinical activity in these rare, life-threatening diseases.