Systematic Review of PD-1/PD-L1 Inhibitors in Oncology: From Personalized Medicine to Public Health.

BACKGROUND: To review and summarize all U.S. Food and Drug Administration (FDA) approvals of programmed death (PD)-1 and PD-ligand 1 blocking antibodies (collectively referred to as PD-[L]1 inhibitors) over a 6-year period and corresponding companion/complementary diagnostic assays. MATERIALS AND METHODS: To determine the indications and pivotal trials eligible for inclusion, approval letters and package inserts available on Drugs@FDA were evaluated for approved PD-[L]1 inhibitors to identify all new indications granted from the first approval of a PD-[L]1 inhibitor on September 4, 2014, through September 3, 2020. The corresponding FDA drug and device reviews from the marketing applications for the approved indications were identified through FDA internal records. Two reviewers independently extracted information for the endpoints, efficacy data, basis for approval, type of regulatory approval, and corresponding in vitro diagnostic device test. The results were organized by organ system and tumor type. RESULTS: Of 70 Biologic Licensing Application or supplement approvals that resulted in new indications, 32 (46%) were granted based on response rate (ORR) and durability of response, 26 (37%) on overall survival, 9 (13%) on progression-free survival, 2 (3%) on recurrence-free survival, and 1 (1%) on complete response rate. Most ORR-based approvals were granted under the accelerated approval provisions and were supported with prolonged duration of response. Overall, 21% of approvals were granted with a companion diagnostic. Efficacy results according to tumor type are discussed. CONCLUSION: PD-[L]1 inhibitors are an effective anticancer therapy in a subset of patients. This class of drugs has provided new treatment options for patients with unmet need across a wide variety of cancer types. Yet, the modest response rates in several tumor types signal a lack of understanding of the biology of these diseases. Further preclinical and clinical investigation may be required to identify a more appropriate patient population, particularly as drug development continues and additional treatment alternatives become available. IMPLICATIONS FOR PRACTICE: The number of PD-[L]1 inhibitors in drug development and the associated companion and complementary diagnostics have led to regulatory challenges and questions regarding generalizability of trial results. The interchangeability of PD-L1 immunohistochemical assays between PD-1/PD-L1 drugs is unclear. Furthermore, robust responses in some patients with low levels of PD-L1 expression have limited the use of PD-L1 as a predictive biomarker across all cancers, particularly in the setting of diseases with few alternative treatment options. This review summarizes the biomarker thresholds and assays approved as complementary and companion diagnostics and provides regulatory perspective on the role of biomarkers in oncology drug development.

FDA review summary of patient-reported outcome results for ibrutinib in the treatment of chronic graft versus host disease.

PURPOSE: On August 2, 2017, the Food and Drug Administration approved ibrutinib (IMBRUVICA) for the treatment of patients with chronic graft versus host disease (cGVHD) after the failure of one or more lines of systemic therapy. The approval was based on results from a single-arm, multicenter trial that enrolled patients with refractory cGVHD. This paper describes the FDA review of patient-reported outcomes (PRO) data from Study PCYC-1129-CA and the decision to incorporate descriptive PRO data in the FDA label to support the primary clinician-reported outcome results. METHODS: In this trial, the Lee Chronic GVHD Symptom Scale (LSS) was used to capture patient-reported symptom bother. The 42 patients who received treatment were included in the analysis and completed the PRO tool. Post hoc descriptive analyses were conducted to further understand the measurement properties of the LSS. RESULTS: The analysis submitted to FDA reported that 18 patients had a ≥ 7-point improvement on the LSS overall summary score at any point during the assessment period. For 10 patients, the ≥ 7-point improvement was sustained for ≥ 2 consecutive PRO assessments. An assessment of the responder threshold suggested the threshold submitted to the FDA was reasonable and in line with clinical findings. CONCLUSIONS: Overall, study PCYC-1129-CA demonstrated favorable clinician-reported cGVHD efficacy results that were complemented by results from PRO data, supporting the FDA's positive benefit-risk assessment leading to regular approval. Limitations included the single-arm trial design, responder definition, and instrument shortcomings. These limitations were thoroughly explored through additional FDA post hoc analyses.

FDA Approval Summary: Brentuximab Vedotin in First-Line Treatment of Peripheral T-Cell Lymphoma.

In November 2018, the U.S. Food and Drug Administration (FDA) approved brentuximab vedotin (BV) for the treatment of adult patients with previously untreated systemic anaplastic large cell lymphoma or other CD30-expressing peripheral T-cell lymphomas (PTCL), including angioimmunoblastic T-cell lymphoma and PTCL not otherwise specified, in combination with cyclophosphamide, doxorubicin, and prednisone (CHP). Approval was based on ECHELON-2, a randomized, double-blind, actively controlled trial that compared BV+CHP with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) in 452 patients with newly diagnosed, CD30-expressing PTCL. Efficacy was based on independent review facility-assessed progression-free survival (PFS). The median PFS was 48.2 months with BV+CHP versus 20.8 months with CHOP, resulting in a hazard ratio (HR) of 0.71 (95% confidence interval [CI]: 0.54-0.93). The trial also demonstrated improvement in overall survival (HR 0.66; 95% CI: 0.46-0.95), complete response rate (68% vs. 56%), and overall response rate (83% vs. 72%) with BV+CHP. The most common adverse reactions (incidence ≥20%) observed ≥2% more with BV+CHP were nausea, diarrhea, fatigue or asthenia, mucositis, pyrexia, vomiting, and anemia. Peripheral neuropathy rates were similar (52% with BV+CHP, 55% with CHOP). Through the Real-Time Oncology Review pilot program, which allows FDA early access to key data, FDA granted this approval less than 2 weeks after official submission of the application. IMPLICATIONS FOR PRACTICE: This is the first U.S. Food and Drug Administration approval for treatment of patients with newly diagnosed peripheral T-cell lymphomas (PTCL). Improvement in progression-free and overall survival over cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy, which has been the standard of care for decades, is unprecedented. The new regimen represents a major advance for the frontline treatment of patients with CD30-expressing PTCL.

FDA Supplemental Approval: Blinatumomab for Treatment of Relapsed and Refractory Precursor B-Cell Acute Lymphoblastic Leukemia.

On July 11, 2017, the Food and Drug Administration granted approval for blinatumomab for the treatment of relapsed or refractory (R/R) precursor B-cell acute lymphoblastic leukemia (ALL). Blinatumomab is a bispecific CD19-directed CD3 T-cell engager. The basis for the approval included results from two clinical trials, TOWER and ALCANTARA. TOWER, a randomized trial comparing overall survival in patients with Philadelphia chromosome (Ph)-negative R/R ALL receiving blinatumomab versus standard-of-care (SOC) chemotherapy, demonstrated a hazard ratio of 0.71 favoring blinatumomab (p = .012; median survival, 7.7 months with blinatumomab and 4.0 months with SOC chemotherapy). Complete remission (CR) rates were 34% for patients receiving blinatumomab and 16% for those receiving SOC. Adverse events were consistent with those observed in prior trials, with cytokine release syndrome and some neurologic events, including tremor, encephalopathy, peripheral neuropathy, and depression, observed more frequently in the blinatumomab arm, whereas neutropenia and infection were less common among patients receiving blinatumomab. Depression emerged as a rare but potentially severe neurologic event associated with blinatumomab. In ALCANTARA, a single-arm trial of blinatumomab in patients with Ph-positive R/R ALL, the CR rate was 31%, and adverse events were similar to those observed previously in Ph-negative R/R ALL. These results support conversion from accelerated to regular approval of blinatumomab for R/R ALL and broadening of the intended population to include both Ph-positive and Ph-negative precursor B-cell R/R ALL. IMPLICATIONS FOR PRACTICE: In TOWER, a randomized trial in patients with relapsed or refractory Philadelphia chromosome (Ph)-negative precursor B-cell acute lymphoblastic leukemia (ALL), treatment with blinatumomab showed superiority over conventional chemotherapy for complete remission (CR) rate (34% vs. 16%) and survival (3.7-month improvement in median; hazard ratio, 0.71). In ALCANTARA, a single-arm trial of blinatumomab for treatment of relapsed or refractory Ph-positive precursor B-cell ALL, the CR rate was 31%. Blinatumomab is now approved for treatment of relapsed or refractory precursor B-cell ALL that is Ph positive or Ph negative.

FDA Approval Summary: Lenalidomide as Maintenance Therapy After Autologous Stem Cell Transplant in Newly Diagnosed Multiple Myeloma.

On February 22, 2017, the U.S. Food and Drug Administration (FDA) granted approval for the use of lenalidomide as maintenance therapy after autologous hematopoietic stem cell transplantation (auto-HSCT) for patients with multiple myeloma. The approval was based on evidence from two randomized, blinded trials of maintenance lenalidomide versus placebo in patients with myeloma who had undergone auto-HSCT along with a third trial of lenalidomide versus no therapy. Each of the trials demonstrated superior progression-free survival for the patients treated with lenalidomide. The effect on overall survival was mixed, with one trial showing longer overall survival and another showing no effect. Subgroup analysis suggested better results for patients with International Staging System stage I or II disease compared with stage III disease. Safety evaluation did not reveal any new safety concerns. More second primary malignancies were observed in the lenalidomide arm compared with the placebo arm. The FDA concluded that lenalidomide maintenance showed a favorable benefit-to-risk ratio when used as maintenance therapy after auto-HSCT. IMPLICATIONS FOR PRACTICE: Prior to this approval, there were no U.S. Food and Drug Administration-approved maintenance therapies for patients with multiple myeloma (MM) who have undergone autologous hematopoietic stem cell transplantation (auto-HSCT). Maintenance therapy with lenalidomide after auto-HSCT in patients with MM demonstrated an approximately 15- to 18-month advantage in progression-free survival compared with placebo at the time of the primary analysis. Patients treated with lenalidomide also appeared to have a survival advantage compared with patients treated with placebo. Because of the high rate of relapse of MM in patients following auto-HSCT and because MM is a serious and often fatal disease, these results appear to be clinically meaningful.

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.

FDA Approval Summary: Tocilizumab for Treatment of Chimeric Antigen Receptor T Cell-Induced Severe or Life-Threatening Cytokine Release Syndrome.

On August 30, 2017, the U.S. Food and Drug Administration approved Actemra (tocilizumab, Genentech, Inc., South San Francisco, CA) for the treatment of severe or life-threatening chimeric antigen receptor (CAR) T cell-induced cytokine release syndrome (CRS) in adults and in pediatric patients 2 years of age and older. The approval was based on a retrospective analysis of data for patients who developed CRS after treatment with CTL019 and KTE-C19 on prospective clinical trials. Evaluable patients had been treated with intravenous tocilizumab 8 mg/kg (12 mg/kg for patients <30 kg) for severe or life-threatening CRS; only the first episode of CRS was included in the analysis. The efficacy population for the CTL019 cohort included 24 male and 21 female patients (total 45 patients) of median age 12 years. The median time from the start of CRS to the first dose of tocilizumab was 4 days (range, 0-18 days). Patients were considered responders if CRS resolved within 14 days of the first dose of tocilizumab, if no more than 2 doses of tocilizumab were needed, and if no drugs other than tocilizumab and corticosteroids were used for treatment. Thirty-one patients (69%; 95% confidence interval, 53%-82%) achieved a response as defined. In an independent cohort of 15 patients with KTE-C19-induced CRS, 53% responded. Further study is needed to determine the optimal dose of tocilizumab and to confirm the safety of its use for treatment of patients with CAR T cell-induced CRS. IMPLICATIONS FOR PRACTICE: Severe or life-threatening chimeric antigen receptor (CAR) T cell-induced cytokine release syndrome (CRS) requires urgent treatment to prevent fatal outcomes. In two independent cohorts, the majority of patients with severe or life-threatening CAR T cell-induced CRS responded to treatment with one or two doses of tocilizumab in addition to advanced supportive care. More research is needed to determine the optimal dose and schedule of tocilizumab for treatment of CAR T cell-induced CRS.

FDA Approval Summary: Mylotarg for Treatment of Patients with Relapsed or Refractory CD33-Positive Acute Myeloid Leukemia.

On September 2, 2017, the U.S. Food and Drug Administration approved gemtuzumab ozogamicin (GO; Mylotarg; Pfizer, New York City, NY) for treatment of relapsed or refractory (R/R) CD33-positive acute myeloid leukemia (AML) in patients 2 years of age and older. GO is a CD33-directed antibody drug conjugate linked to the cytotoxic antibiotic calicheamicin. It originally received accelerated approval for treatment of older patients with relapsed CD33-positive AML in 2000, but it was withdrawn from the market in 2010 when the confirmatory trial failed to demonstrate clinical benefit among safety concerns, such as a higher rate of induction fatalities on the GO combination arm compared with chemotherapy alone. In addition, GO was associated with hepatic veno-occlusive disease (VOD), which has substantial morbidity and mortality. Pharmacokinetic analyses suggested a lower maximum concentration of GO would result in less VOD without affecting target saturation or efficacy. A meta-analysis across dose schedules of GO in patients with R/R AML showed that a lower-dose "fractionated" schedule of 3 mg/m2 days 1, 4, and 7 was associated with less early mortality, hemorrhage, and VOD, without an apparent decrease in complete remission (CR) rate. MyloFrance 1 was a single-arm study evaluating response rates in patients with relapsed CD33-positive AML treated with the lower-dose fractionated GO regimen. The CR rate was 26% (95% confidence interval 16%-40%). Common adverse reactions were fever, infections, nausea, vomiting, constipation, bleeding, increased liver enzymes, and mucositis. There were no cases of VOD. These results supported the approval of GO as monotherapy for R/R CD33-positive AML using the lower-dose fractionated regimen. IMPLICATIONS FOR PRACTICE: Gemtuzumab ozogamicin (GO) 3 mg/m2 days 1, 4, and 7 is an active regimen for induction of remission when used to treat patients with relapsed or refractory CD33-positive acute myeloid leukemia without curative intent. The risks of hepatic veno-occlusive disease and early mortality with this regimen appear to be lower than reported previously for GO 9 mg/m2 days 1 and 15. The data were not sufficient to enable conclusions about the safety of GO in children younger than 2 years of age.

FDA Approval Summary: Nivolumab for the Treatment of Relapsed or Progressive Classical Hodgkin Lymphoma.

On May 17, 2016, after an expedited priority review, the U.S. Food and Drug Administration granted accelerated approval to nivolumab for the treatment of patients with classical Hodgkin lymphoma (cHL) that has relapsed or progressed after autologous hematopoietic stem cell transplantation (HSCT) and post-transplantation brentuximab vedotin (BV). Nivolumab in cHL had been granted breakthrough therapy designation. Accelerated approval was based on two single-arm, multicenter trials in adults with cHL. In 95 patients with relapsed or progressive cHL after autologous HSCT and post-transplantation BV, nivolumab, dosed at 3 mg/kg intravenously every 2 weeks, produced a 65% (95% confidence interval: 55%-75%) objective response rate (58% partial remission, 7% complete remission). The estimated median duration of response was 8.7 months, with 4.6-month median follow-up for response duration. The median time to response was 2.1 (range: 0.7-5.7) months. Among 263 patients with cHL treated with nivolumab, 21% reported serious adverse reactions (ARs). The most common all-grade ARs (reported in ≥20%) were fatigue, upper respiratory tract infection, cough, pyrexia, diarrhea, elevated transaminases, and cytopenias. Infusion-related reaction and hypothyroidism or thyroiditis occurred in >10% of patients; other immune-mediated ARs, occurring in 1%-5%, included rash, pneumonitis, hepatitis, hyperthyroidism, and colitis. A new Warning and Precaution was issued for complications of allogeneic HSCT after nivolumab, including severe or hyperacute graft-versus-host disease, other immune-mediated ARs, and transplant-related mortality. Continued approval for the cHL indication may be contingent upon verification of clinical benefit in a randomized trial. The Oncologist 2017;22:585-591 IMPLICATIONS FOR PRACTICE: Based on response rate and duration in single-arm studies, nivolumab is a new treatment option for patients with classical Hodgkin lymphoma (cHL) that has relapsed or progressed despite autologous hematopoietic stem cell transplantation (HSCT) and brentuximab vedotin. This was the first U.S. Food and Drug Administration marketing application for a programmed cell death 1 inhibitor in hematologic malignancies. The use of immune checkpoint blockade in cHL represents a new treatment paradigm. The safety of allogeneic HSCT after nivolumab requires further evaluation, as does the safety of nivolumab after allogeneic HSCT.

FDA Approval Summary: Daratumumab for Treatment of Multiple Myeloma After One Prior Therapy.

On November 21, 2016, the U.S. Food and Drug Administration granted regular approval to daratumumab in combination with lenalidomide and dexamethasone, or bortezomib and dexamethasone, for the treatment of patients with multiple myeloma who have received at least one prior therapy. Approval was based on two randomized, open-label trials in which daratumumab was added to these backbone therapies. The MMY3003 trial demonstrated substantial improvement in progression-free survival (PFS) when daratumumab was added to lenalidomide and dexamethasone compared with lenalidomide and dexamethasone alone. The estimated median PFS had not been reached in the daratumumab arm and was 18.4 months in the control arm (hazard ratio [HR] = 0.37; 95% confidence interval [CI]: 0.27-0.52; p < .0001), representing a 63% reduction in the risk of disease progression or death. Similar results were observed in the MMY3004 trial comparing the combination of daratumumab, bortezomib, and dexamethasone with bortezomib and dexamethasone. The estimated median PFS was not reached in the daratumumab arm and was 7.2 months in the control arm (HR = 0.39; 95% CI: 0.28-0.53; p < .0001), representing a 61% reduction in the risk of disease progression or death. The most frequently reported adverse reactions (greater than or equal to 20%) in MMY3003 were infusion reactions, diarrhea, nausea, fatigue, pyrexia, upper respiratory tract infection, muscle spasm, cough, and dyspnea. The most frequently reported adverse reactions (greater than or equal to 20%) in MMY3004 were infusion reactions, diarrhea, peripheral edema, upper respiratory tract infection, and peripheral sensory neuropathy. Neutropenia and thrombocytopenia have been added to the Warnings and Precautions of the drug label. IMPLICATIONS FOR PRACTICE: Daratumumab, the first monoclonal antibody targeted against CD38, received U.S. Food and Drug Administration accelerated approval in 2015 based on data from single-agent, single-arm trials that provided response rate information. Results of the MMY3003 and MMY3004 trials established that daratumumab can be combined synergistically with some of the most highly active agents used to treat multiple myeloma, leading to daratumumab's regular approval in 2016. Daratumumab added to lenalidomide and dexamethasone, or bortezomib and dexamethasone, provides a substantial improvement in progression-free survival in previously treated patients with multiple myeloma. These combinations will likely improve the survival outlook for patients with multiple myeloma.

U.S. Food and Drug Administration approval summary: Eltrombopag for the treatment of pediatric patients with chronic immune (idiopathic) thrombocytopenia.

The U.S. Food and Drug Administration (FDA) approved eltrombopag for pediatric patients with chronic immune (idiopathic) thrombocytopenia (ITP) ages ≥6 on June 11, 2015, and ages ≥1 on August 24, 2015. Approval was based on the FDA review of two randomized trials that included 159 pediatric patients with chronic ITP who had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. This manuscript describes the basis for approval of these applications. The FDA concluded that eltrombopag has shown efficacy and a favorable benefit to risk profile for pediatric patients with chronic ITP.

U.S. Food and Drug Administration approval summary: omacetaxine mepesuccinate as treatment for chronic myeloid leukemia.

On October 26, 2012, the U.S. Food and Drug Administration (FDA) granted accelerated approval to omacetaxine mepesuccinate (Synribo; Teva Pharmaceuticals USA, Inc., North Wales, PA, http://www.tevausa.com) for the treatment of adult patients with chronic phase (CP) or accelerated phase (AP) chronic myeloid leukemia (CML) with resistance and/or intolerance to two or more tyrosine kinase inhibitors (TKIs). The approval was based on the FDA review of data from 111 patients with CML in CP or in AP who had received two or more prior TKIs, including imatinib. Major cytogenetic response was achieved in 18% of patients with CP, with a median response duration of 12.5 months. Major hematologic response was achieved in 14% of patients with AP, with a median response duration of 4.7 months. The FDA safety evaluation was based on submitted data from 163 patients with CP or AP CML who had received at least one dose of omacetaxine mepesuccinate. The safety evaluation was limited by the single-arm design of the clinical trials as conducted in a small number of previously treated patients. The most common (≥20%) adverse reactions of any grade in enrolled patients included thrombocytopenia, anemia, neutropenia, diarrhea, nausea, fatigue, asthenia, injection site reaction, pyrexia, and infection. The FDA concluded that omacetaxine mepesuccinate has shown activity and a favorable benefit-to-risk profile for the studied population of adult patients with CML (CP or AP) with resistance and/or intolerance to two or more TKIs. Further evidence of response durability to verify clinical benefit is pending.

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.

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.

The role of the U.S. Food and Drug Administration review process: clinical trial endpoints in oncology.

The U.S. Food and Drug Administration grants marketing approval for drug products based on a comprehensive review of safety and efficacy data. The clinical trial endpoints that have been used to support approval in the oncology setting have evolved over the last 30 years commensurate with an improved understanding of the natural history of cancers and the mechanisms of action of drugs. Overall survival is the gold standard for a registration trial designed to gain marketing approval; however, additional endpoints have been used in the approval of oncology drugs. Advantages of specific endpoints are discussed, including the accuracy of an endpoint's measurement and its relation to clinical benefit. Surrogate endpoints may be acceptable for "accelerated" approval, with a sponsor commitment to provide evidence of clinical benefit in a subsequent trial.

FDA approval summary: temsirolimus as treatment for advanced renal cell carcinoma.

This report summarizes the U.S. Food and Drug Administration (FDA)'s approval of temsirolimus (Torisel), on May 30, 2007, for the treatment of advanced renal cell carcinoma (RCC). Information provided includes regulatory history, study design, study results, and literature review. A multicenter, three-arm, randomized, open-label study was conducted in previously untreated patients with poor-prognosis, advanced RCC. The study objectives were to compare overall survival (OS), progression-free survival (PFS), objective response rate, and safety in patients receiving interferon (IFN)-alpha versus those receiving temsirolimus alone or in combination with IFN-alpha. In the second planned interim analysis of the intent-to-treat population (n = 626), there was a statistically significant longer OS time in the temsirolimus (25 mg) arm than in the IFN-alpha arm (median, 10.9 months versus 7.3 months; hazard ratio [HR], 0.73; p = .0078). The combination of temsirolimus (15 mg) and IFN-alpha did not lead to a significant difference in OS compared with IFN-alpha alone. There was also a statistically significant longer PFS time for the temsirolimus (25 mg) arm than for the IFN-alpha arm (median, 5.5 months versus 3.1 months; HR, 0.66, p = .0001). Common adverse reactions reported in patients receiving temsirolimus were rash, asthenia, and mucositis. Common laboratory abnormalities were anemia, hyperglycemia, hyperlipidemia, and hypertriglyceridemia. Serious but rare cases of interstitial lung disease, bowel perforation, and acute renal failure were observed. Temsirolimus has demonstrated superiority in terms of OS and PFS over IFN-alpha and provides an additional treatment option for patients with advanced RCC.

Older adults in hematologic malignancy trials: Representation, barriers to participation and strategies for addressing underrepresentation.

Despite a high incidence of hematologic malignancies in older adults, available data indicate that there is disproportionately low representation of adults ≥65 years with hematologic malignancies (greater in patients ≥75 years) in clinical trials. Biological and clinical differences between older and younger adults and diversity within older patients necessitate adequate representation of the older subpopulation in hematologic malignancy trials. This would allow trial results to be generalizable and inform treatment decisions in the older patient population. Restrictive eligibility criteria may be barriers to adequate representation, as older adults do not typically meet these criteria. Efforts to broaden eligibility criteria in clinical trials have been proposed and may promote enrollment of a representative older population with hematologic malignancies. Collaboration among a diverse group of stakeholders will be needed to implement current proposals and evaluate their impact on increasing representation of older adults in trials evaluating therapies for hematologic malignancies.

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.

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.