FDA Grants Priority Review for Immunotherapy-Based Lung Cancer Combination

Jason M. Broderick

The Food and Drug Administration (FDA) granted a priority review to a supplemental biologics license application (sBLA) for frontline Keytruda (pembrolizumab) for use in combination with standard chemotherapy for patients with metastatic nonsquamous non–small cell lung cancer (NSCLC), according to Merck (MSD), the manufacturer of the PD-1 inhibitor. 

The sBLA is based on the phase 3 KEYNOTE-189 trial, in which adding Keytruda to Alimta (pemetrexed) and either cisplatin or carboplatin in the first-line setting reduced the risk of death by over 50 percent in patients with NSCLC without EGFR or ALK mutations.

At a median follow-up of 10.5 months, the estimated 12-month overall survival (OS) rate was 69.2 percent in the Keytruda arm compared with 49.4 percent in the control group. 

The median OS was not reached in the Keytruda cohort, compared with 11.3 months in the chemotherapy-alone arm. The OS benefit was observed, irrespective of PD-L1 status. The study also met the coprimary endpoint of progression-free survival (PFS), with a median PFS of 8.8 months in the Keytruda group versus 4.9 months in the control arm.

The study is a confirmatory trial to convert the accelerated approval of Keytruda in this setting to a full approval. The accelerated approval was based on cohort G in the KEYNOTE-021 trial, in which the 12-month PFS rate was 56 percent with Keytruda combined with Alimta and carboplatin compared with 34 percent with chemotherapy alone.

“Keytruda is the first immunotherapy to significantly extend survival of patients with nonsquamous non–small cell lung cancer in combination with chemotherapy as a first-line treatment, including in patients whose tumors are either PD-L1 negative or are untested,” Roger M. Perlmutter, M.D., Ph.D., president, Merck Research Laboratories, said in a statement. “With this sBLA acceptance by the FDA, we are pleased that data from KEYNOTE-189 is now under review by regulatory authorities in the United States, Europe, and Japan.”

The double-blind phase 3 KEYNOTE-189 study accrued 616 patients with advanced or metastatic nonsquamous NSCLC, regardless of PD-L1 expression. Patients were not EGFR- or ALK-positive, and had not received systemic therapy for advanced disease. The trial randomization was 2:1 in favor of the Keytruda arm.

In the experimental arm (410 patients), patients received Keytruda at a 200-mg fixed dose every three weeks plus 500 mg/m2 of Alimta plus either 75 mg/m2 of cisplatin or carboplatin (AUC 5) on day 1 every three weeks for four cycles, followed by 200 mg of Keytruda plus 500 mg/m2 of Alimta every three weeks. The regimen administered to the control group (206 patients) was identical, except that Keytruda was replaced with placebo. 

Treatment was administered until disease progression, unacceptable toxicity, physician decision, or consent withdrawal. Patients in the control arm with disease progression were allowed to cross over to receive Keytruda. Beyond the primary OS and PFS endpoints, secondary endpoints included overall response rate (ORR) and duration of response.

Patient characteristics were well balanced between the two arms. The median age was 65  years in the Keytruda arm (range, 34.0-84.0), 62 percent of the patients were male, and all but one of the patients had an ECOG performance status of 0 or 1. Current/former smokers comprised 88.3 percent of the cohort and 96.1 percent of patients had adenocarcinoma. 

Also in the Keytruda group, PD-L1 expression level as measured by tumor proportion score ( percent of tumor cells with membranous PD-L1 staining) was less than 1 percent in 31 percent of patients; more than 1 percent in 63.4 percent; 1 percent to 49 percent in 31.2 percent of patients; at least 50 percent in 32.2 percent; and not evaluable in 5.6 percent.

The Keytruda OS benefit was observed across PD-L1 subgroups, including the less than 1 percent expression group (12-month OS rate, 61.7 percent vs. 52.2 percent); the 1 percent to 49 percent cohort (12-month OS rate, 71.5 percent vs. 50.9 percent), and those with a score of 50 percent or greater (12-month OS rate, 73.0 percent vs. 48.1 percent).

The ORR per blinded, independent central radiologic review was 47.6 percent in the Keytruda arm and 18.9 percent with chemotherapy alone. The disease control rate was 84.6 percent versus 70.4 percent, and the median duration of response was 11.2 months versus 7.8 months in the Keytruda versus control arms, respectively.

The rate of discontinuation of all study drugs due to adverse events (AEs) was 13.8 percent in the Keytruda arm compared with 7.9 percent in the control arm. The discontinuation rate of Keytruda was 20.2 percent and placebo was 10.4 percent. Death related to AEs occurred in 6.7 percent versus 5.9 percent of the Keytruda versus control arms, respectively.

Diarrhea (30.9 percent vs 21.3 percent) and rash (20.2 percent vs 11.4 percent) were the only 2 AEs occurring in at least 10 percent of patients that occurred more commonly in the Keytruda versus the chemotherapy-alone arm. Grade ≥3 AEs occurring in at least 10 percent of patients in either arm were anemia (16.3 percent with Keytruda vs 15.3 percent in the control group) and neutropenia (15.8 percent vs 11.9 percent, respectively).

The rate of acute kidney injury was 5.2 percent in the Keytruda arm versus 0.5 percent in the chemotherapy-alone arm. Eight patients (2  percent) receiving the PD-1 inhibitor had grade ≥3 acute kidney injury.

Immune-mediated AEs occurred in 22.7 percent of the Keytruda group versus 11.9 percent of the control group, including grade 3 or higher AEs in 8.9 percent versus 4.5 percent, respectively. Pneumonitis led to 3 deaths in the Keytruda cohort. 

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