FDA OKs First Targeted Therapy for Subset of Patients With NSCLC

Nick Mulcahy

May 21, 2021

The US Food and Drug Administration (FDA) today granted an accelerated approval for amivantamab (Rybrevant) as the first targeted treatment for patients with non–small cell lung cancers (NSCLC) harboring epidermal growth factor receptor (EGFR) exon 20 insertion mutations.

The FDA also approved the Guardant360 CDx as a companion diagnostic for the new drug.

"With today's approval, for the first time, patients with non–small cell lung cancer with EGFR exon 20 insertion mutations will have a targeted treatment option," said Julia Beaver, MD, chief of medical oncology in the FDA's Oncology Center of Excellence and acting deputy director of the Office of Oncologic Diseases in the FDA's Center for Drug Evaluation and Research in a press statement.

NSCLC accounts for 80% to 85% of all lung cancers. Approximately 2% to 3% of those patients will have EGFR exon 20 insertion mutations, which help trigger rapid cancer cell growth and spread, according to the FDA.

Treatment of patients with NSCLC whose cancers have these mutations has been a "challenge," in part because EGFR exon 20 insertion mutations do not allow optimal binding of standard therapy with tyrosine kinase inhibitors (TKIs), resulting in limited efficacy, explained Karen Reckamp, MD, of Cedars-Sinai Cancer Institute, Los Angeles, California, earlier this year at a conference; she was not involved with the drug's development.

This is an accelerated approval based on data for response rates from a phase 1 clinical trial, dubbed CHRYSALIS. It involved 81 patients with NSCLC with EGFR exon 20 insertion mutations who had experienced disease progression with platinum-based chemotherapy. All patients received amivantamab. Those who weighed <80 kg received a dose of 1050 mg, and those who weighed ≥80 kg received a dose of 1400 mg.

The overall response rate with amivantamab, which was the primary outcome, was 40%; the median duration of response was 11.1 months. For 63% of patients, the duration of response was 6 months or longer.

Median follow-up was 9.7 months.

According to data from the study first presented earlier this year at the World Conference on Lung Cancer, the median age of the patients was 62 years, and 41% were men. The majority of patients were Asian (49%) or White (37%). Just over half (53%) were nonsmokers. The median number of prior lines of therapy was two; 46% of patients had undergone immunotherapy in addition to chemotherapy, and 25% had received a TKI.

The drug appeared to be effective across subgroups that were based on age, sex, race, prior lines of therapy, and history of smoking.

A safety analysis based on this phase 1 study and on a prior dose-escalation study showed that the most common treatment-emergent adverse events were rash (86%), infusion-related reactions (66%), and paronychia (45%). Stomatitis (21%) and pruritus (17%) were also reported. Diarrhea occurred in 12% of patients; for 3.5% of patients, the diarrhea was of grade 3.

Adverse events of grade ≥3 were reported in 35% of patients; 16% of those events were considered treatment related. Rash (4%) and infusion-related reactions (3%) were the most frequent.

No treatment-related deaths were reported. Treatment-related adverse events led to dose reductions in 13% of patients and to discontinuation in 4%.

According to the FDA, the new drug should be withheld if patients develop symptoms of interstitial lung disease, and it should be discontinued if such disease is confirmed. Patients should have limited sun exposure during treatment and for 2 months after treatment. Amivantamab may cause problems with vision.

Larger Clinical Trials Underway

Clinical trials of the new drug in untreated advanced EGFR-mutated NSCLC are ongoing, including the phase 3 MARIPOSA and PAPILLON combination trials.

In addition, data from a trial investigating amivantamab in combination with lazertinib will be presented at the forthcoming American Society of Clinical Oncology (ASCO) Annual Meeting (abstract 9006); those data show durable responses for NSCLC patients with other types of EGFR mutations who experience relapsed while taking osimertinib, according to the manufacturer.

This review was conducted under Project Orbis, an initiative of the FDA Oncology Center of Excellence.

Nick Mulcahy is an award-winning senior journalist for Medscape whose work focuses on oncology. He can be reached at nmulcahy@medscape.net and on Twitter: @MulcahyNick.

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