FDA Approves Bispecific Antibody RYBREVANT® for Metastatic Non Small Cell Lung Cancer

SUMMARY: The FDA on May 21, 2021, granted accelerated approval to RYBREVANT® (Amivantamab-vmjw), a bispecific antibody directed against Epidermal Growth Factor (EGF) and MET receptors, for adult patients with locally advanced or metastatic Non Small Cell Lung Cancer (NSCLC) with Epidermal Growth Factor Receptor (EGFR) exon 20 insertion mutations, as detected by an FDA-approved test, whose disease has progressed on or after Platinum-based chemotherapy. FDA also approved the Guardant360® CDx (Guardant Health, Inc.) as a companion diagnostic for RYBREVANT®.

The American Cancer Society estimates that for 2021, about 235,760 new cases of lung cancer will be diagnosed and 131,880 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non-Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers. Of the three main subtypes of NSCLC, 30% are Squamous Cell Carcinomas (SCC), 40% are Adenocarcinomas and 10% are Large Cell Carcinomas. With changes in the cigarette composition and decline in tobacco consumption over the past several decades, Adenocarcinoma now is the most frequent histologic subtype of lung cancer.

Approximately 10-15% of Caucasian patients and 35-50% of Asian patients with Adenocarcinomas, harbor activating EGFR mutations and 90% of these mutations are either exon 19 deletions or L858R substitution mutation in exon 21. EGFR exon 20 insertion mutations are the third most common after L858R and exon 19 deletions, and occur in about 2-3% patients with NSCLC and are insensitive to EGFR Tyrosine Kinase Inhibitors (TKIs) due to an altered conformation of the kinase active site. Next-Generation sequencing provides an alternative to Polymerase Chain Reaction (PCR)-based tests, which fail to identify 50% or more of exon 20 insertion mutations. Patients with EGFR exon 20 insertion mutations have a 5 year Overall Survival (OS) of 8% in the frontline setting, compared to an OS of 19% for patients with EGFR exon 19 deletions or L858R mutations. There is therefore a clinically unmet need for this patient group, as there are no approved targeted therapies available and platinum-doublet chemotherapy remains the standard of care for these patients.

Epidermal Growth Factor Receptor (EGFR) plays an important role in regulating cell proliferation, survival and differentiation, and is overexpressed in a variety of epithelial malignancies. EGFR targeted Tyrosine Kinase Inhibitors (TKIs) such as Gefitinib, Erlotinib, Afatinib, Dacomitinib and Osimertinib target the EGFR signaling cascade. However, patients eventually will develop drug resistance due to new EGFR mutations. Another important cause of drug resistance to TKIs is due to the activation of parallel RTK (Receptor Tyrosine Kinase) pathways such as Hepatocyte Growth Factor/Mesenchymal-Epithelial Transition factor (HGF/MET) pathway, thereby bypassing EGFR TKI inhibitors.

RYBREVANT® is a fully-human bispecific antibody directed against EGFR and MET receptors. RYBREVANT® binds extracellularly and simultaneously blocks ligand-induced phosphorylation of EGFR and c-MET, inhibiting tumor growth and promoting tumor cell death. Further, RYBREVANT® downregulates receptor expression on tumor cells thus preventing drug resistance mediated by new emerging mutations of EGFR or c-MET. By binding to the extracellular domain of the receptor protein, RYBREVANT® can bypass primary and secondary TKI resistance at the active site.

The present FDA approval was based on CHRYSALIS, an ongoing multicenter, non-randomized, open label, multicohort, Phase I clinical trial (NCT02609776) which included patients with locally advanced or metastatic NSCLC with EGFR exon 20 insertion mutations. The purpose of study is to evaluate the safety, pharmacokinetics, and preliminary efficacy of RYBREVANT® as a monotherapy and in combination with Lazertinib, and to determine the recommended Phase 2 dose (RP2D) (monotherapy), recommended Phase 2 combination dose (RP2CD) (combination therapy), and to determine recommended Phase 2 Dose (RP2q3W) with combination chemotherapy (RYBREVANT® in combination with standard of care Carboplatin and Pemetrexed) in 21 day treatment cycle for participants with advanced NSCLC.

In this analysis of the Phase 1 CHRYSALIS study, researchers assessed the efficacy and safety of RYBREVANT® in patients with NSCLC and EGFR exon 20 insertion mutations, who had progressed on prior Platinum-based chemotherapy, and were treated at the recommended Phase II dose of RYBREVANT® 1050 mg (1400 mg for patients weighting 80 kg or more). The median patient age was 61 years, 51% were female, and median prior lines of therapy was one. The Primary endpoint was Overall Response Rate (ORR). Secondary endpoints included Duration of Response (DOR), Clinical Benefit Rate, Progression Free Survival (PFS) and Overall Survival (OS).

It was noted that among this post-platinum cohort of patients (N=81), at a median follow up of 9.7 months, the ORR was 40%, with 4% Complete Reponses and 36% achieving Partial Responses (PR). Responses were durable with median Duration of Response of 11.1 months, with 63 % having responses of at least six months or greater duration. The median PFS was 8.3 months and median OS was 22.8 months. The Clinical Benefit Rate (PR or more, or Stable Disease of 11 weeks or more) was 74%. The most common adverse reactions (20% or more) were rash, infusion-related reactions, paronychia, fatigue, musculoskeletal pain, stomatitis, nausea, vomiting, constipation, edema, cough and dyspnea.

The authors concluded that RYBREVANT® demonstrated robust and durable antitumor activity in patients with EGFR exon 20 insertion mutations, with a manageable safety profile.

Amivantamab in Post-platinum EGFR Exon 20 Insertion Mutant Non-small Cell Lung Cancer. Sabari JK, Shu CA, Park K, et al. Presented at: IASLC 2020 World Conference on Lung Cancer Singapore. January 28-31, 2021. Abstract OA04.04