US Food and Drug Administration Approval Summary: Elacestrant for Estrogen Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative, ESR1-Mutated Advanced or Metastatic Breast Cancer.

PURPOSE: The US Food and Drug Administration (FDA) approved elacestrant for the treatment of postmenopausal women or adult men with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-), estrogen receptor 1 (ESR1)-mutated advanced or metastatic breast cancer with disease progression after at least one line of endocrine therapy (ET). PATIENTS AND METHODS: Approval was based on EMERALD (Study RAD1901-308), a randomized, open-label, active-controlled, multicenter trial in 478 patients with ER+, HER2- advanced or metastatic breast cancer, including 228 patients with ESR1 mutations. Patients were randomly assigned (1:1) to receive either elacestrant 345 mg orally once daily (n = 239) or investigator's choice of ET (n = 239). RESULTS: In the ESR1-mut subgroup, EMERALD demonstrated a statistically significant improvement in progression-free survival (PFS) by blinded independent central review assessment (n = 228; hazard ratio [HR], 0.55 [95% CI, 0.39 to 0.77]; P value = .0005). Although the overall survival (OS) end point was not met, there was no trend toward a potential OS detriment (HR, 0.90 [95% CI, 0.63 to 1.30]) in the ESR1-mut subgroup. PFS also reached statistical significance in the intention-to-treat population (ITT, N = 478; HR, 0.70 [95% CI, 0.55 to 0.88]; P value = .0018). However, improvement in PFS in the ITT population was primarily attributed to results from patients in the ESR1-mut subgroup. More patients who received elacestrant experienced nausea, vomiting, and dyslipidemia. CONCLUSION: The approval of elacestrant in ER+, HER2- advanced or metastatic breast cancer was restricted to patients with ESR1 mutations. Benefit-risk assessment in the ESR1-mut subgroup was favorable on the basis of a statistically significant improvement in PFS in the context of an acceptable safety profile including no evidence of a potential detriment in OS. By contrast, the benefit-risk assessment in patients without ESR1 mutations was not favorable. Elacestrant is the first oral estrogen receptor antagonist to receive FDA approval for patients with ESR1 mutations.

Highlights of FDA Oncology Approvals in 2023: Bispecific T-cell Engagers, Pediatric Indications, and Inclusive Drug Development.

SUMMARY: Cancer drug development remained robust in 2023. Highlights of U.S. drug approvals this year include new immunotherapies and targeted drug development in adult and pediatric patients as well as patients with rare diseases.

FDA Approval Summary: Mirvetuximab Soravtansine-Gynx for FRα-Positive, Platinum-Resistant Ovarian Cancer.

On November 14, 2022, the FDA granted accelerated approval to mirvetuximab soravtansine-gynx for treatment of adult patients with folate receptor-α (FRα)-positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer who have received one to three prior systemic therapies. The VENTANA FOLR1 (FOLR-2.1) RxDx Assay was approved as a companion diagnostic device to select patients for this indication. Approval was based on Study 0417 (SORAYA, NCT04296890), a single-arm, multicenter trial. In 104 patients with measurable disease who received mirvetuximab soravtansine-gynx, the overall response rate was 31.7% [95% confidence interval (CI), 22.9-41.6] with a median duration of response of 6.9 months (95% CI, 5.6-9.7). Ocular toxicity was included as a Boxed Warning in the U.S. Prescribing Information (USPI) to alert providers of the risks of developing severe ocular toxicity including vision impairment and corneal disorders. Pneumonitis and peripheral neuropathy were additional important safety risks included as Warnings and Precautions in the USPI. This is the first approval of a targeted therapy for FRα-positive, platinum-resistant ovarian cancer and the first antibody-drug conjugate approved for ovarian cancer. This article summarizes the favorable benefit-risk assessment leading to FDA's approval of mirvetuximab soravtansine-gynx.

FDA Approval Summary: Pembrolizumab for Neoadjuvant and Adjuvant Treatment of Patients with High-Risk Early-Stage Triple-Negative Breast Cancer.

On July 26, 2021, the FDA granted approval to pembrolizumab in combination with chemotherapy for neoadjuvant treatment and then continued as a single agent for adjuvant treatment following surgery for patients with high-risk, early-stage triple-negative breast cancer. Approval was based on results from KEYNOTE-522, an ongoing randomized (2:1) trial evaluating pembrolizumab or placebo in combination with chemotherapy for neoadjuvant treatment and then as a single agent for adjuvant treatment. The co-primary endpoints were pathological complete response (pCR) rate and event-free survival (EFS). The trial demonstrated an improvement in pCR and EFS in the pembrolizumab arm compared with the control arm. The number of patients who experienced an EFS event was 123 (16%) and 93 (24%), respectively [HR: 0.63, 95% confidence interval (CI), 0.48-0.82, P = 0.00031]. Patients on the pembrolizumab arm experienced EFS benefit regardless of tumor PD-L1 status. The absolute pCR rate improvement with the addition of pembrolizumab was 7.5% (95% CI, 1.6-13.4). Among patients receiving pembrolizumab, 44% experienced an immune-related adverse reaction. This article summarizes FDA's review of pembrolizumab and the data supporting the favorable benefit-risk assessment.

FDA Approval Summary: Belzutifan for von Hippel-Lindau Disease-Associated Tumors.

On August 13, 2021, the FDA approved belzutifan (WELIREG, Merck), a first-in-class hypoxia-inducible factor (HIF) inhibitor for adult patients with von Hippel-Lindau (VHL) disease who require therapy for associated renal cell carcinoma (RCC), central nervous system (CNS) hemangioblastomas, or pancreatic neuroendocrine tumors (pNET), not requiring immediate surgery. The FDA granted approval based on the clinically meaningful effects on overall response rate (ORR) observed in patients enrolled in Study MK-6482-004. All 61 patients had VHL-associated RCC; some also had CNS hemangioblastomas and/or pNET. For VHL disease-associated RCC, ORR was 49% [95% confidence interval (CI), 36-62], median duration of response (DoR) was not reached, 56% of responders had DoR ≥12 months, and median time to response was 8 months. Twenty-four patients had measurable CNS hemangioblastomas with an ORR of 63% (95% CI, 41-81), and 12 patients had measurable pNET with an ORR of 83% (95% CI, 52-98). For these tumors, median DoR was not reached, with 73% and 50% of patients having response durations ≥12 months for CNS hemangioblastomas and pNET, respectively. The most common adverse reactions, including laboratory abnormalities, reported in ≥20% were anemia, fatigue, increased creatinine, headache, dizziness, increased glucose, and nausea. Belzutifan can render some hormonal contraceptives ineffective and can cause embryo-fetal harm during pregnancy. This article summarizes the data and the FDA thought process supporting traditional approval of belzutifan for this indication.

FDA Approval Summary: Abemaciclib With Endocrine Therapy for High-Risk Early Breast Cancer.

PURPOSE: The US Food and Drug Administration approved abemaciclib in combination with endocrine therapy (ET) for the adjuvant treatment of adult patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative, node-positive, early breast cancer (EBC) at high risk of recurrence and a Ki-67 score ≥ 20%. PATIENTS AND METHODS: The approval was based on monarchE, a phase III, open-label, 2-cohort, multicenter trial of patients with EBC randomly assigned to receive abemaciclib plus ET (n = 2,808) or ET alone (n = 2,829). Abemaciclib was given at 150 mg orally twice daily for 2 years. RESULTS: Invasive disease-free survival (IDFS) in the intent-to-treat population was statistically significant at the second IDFS interim analysis (IA; March 2020; hazard ratio [HR; 95% CI], 0.747 [0.598 to 0.932]; P = .0096); however, only 12.5% of patients had completed adjuvant therapy, and the HR for overall survival (OS) was > 1. A prespecified, controlled analysis of IDFS in patients with Ki-67 ≥ 20% in cohort 1 was statistically significant at the final IDFS analysis (July 2020; HR [95% CI], 0.643 [0.475 to 0.872]; P = .0042). At the first OS IA (April 2021), the majority of patients had completed adjuvant therapy, IDFS remained consistent, and potential detriment in OS was not observed for this subgroup (HR [95% CI], 0.767 [0.511 to 1.152]). The HR for OS in the intent-to-treat population at OS IA remained > 1 (HR [95% CI], 1.091 [0.818 to 1.455]). More patients in the abemaciclib plus ET arm experienced treatment emergent adverse events (all grades 98.4% v 88.8%, grade 3 ≥ 49.7% v 16.3%). CONCLUSION: The approval of abemaciclib in adjuvant EBC was limited to patients with high risk of recurrence and Ki-67 ≥ 20%, given their favorable benefit:risk with a statistically significant IDFS advantage and no observed detriment on survival.