Risk of Death Reduced With Upfront Pembrolizumab/Chemotherapy in Squamous NSCLC

Luis Paz-Ares, MD, PhD

According to the phase III KEYNOTE-407 trial, when pembrolizumab (Keytruda) was added to frontline carboplatin/paclitaxel or nab-paclitaxel (Abraxane), the combination reduced the risk of death by 36% compared with chemotherapy alone for patients with metastatic squamous non—small cell lung cancer (NSCLC). 

Of the patients treated with pembrolizumab, the median overall survival (OS) was 15.9 months (95% CI, 13.2 — not evaluable) compared to 11.3 months (95% CI, 9.5-14.8) in patients treated with chemotherapy alone (HR, 0.64; 95% CI, 0.49-0.85;P= .0008. OS benefit was observed regardless of PD-L1 expression level, choice of taxane, age, sex, and ECOG performance status.

Progression-free survival (PFS) was also improved with the addition of pembrolizumab. The median PFS was 6.4 months (95% CI, 6.2-8.3) with the PD-1 inhibitor compared with 4.8 months (95% CI, 4.3-5.7) with chemotherapy alone (HR, 0.56; 95% CI, 0.45-0.70;P<.0001). While the PFS benefit was also observed across all PD-L1 expression levels, there was a correlation between an increase in PD-L1 level and a greater magnitude of benefit.

&ldquo;The data suggest that pembrolizumab plus carboplatin and paclitaxel or nab-paclitaxel should become a new standard of care for first-line treatment of metastatic squamous NSCLC, irrespective of PD-L1 expression,&rdquo; said lead author Luis Paz-Ares, MD, PhD, professor of Medicine at the Hospital Universitario 12 de Octubre, Madrid, during a presentation at the 2018 ASCO Annual Meeting.

The objective response rate (ORR) in the pembrolizumab arm was 57.9%, comprising a complete response (CR) rate of 1.4% and a partial response (PR) rate of 56.5%. In the control arm, the ORR was 38.4%, comprising a CR rate of 2.1% and a PR rate of 36.3%. The duration of response was 7.7 months (range, 1.1+ to 14.7+) versus 4.8 months (1.3+ to 15.8+) in the pembrolizumab versus placebo arms, respectively.

In the pembrolizumab cohort, 28.1% of patients had stable disease, 6.1% had progressive disease, and 2.2% of patients were not evaluable for response. The corresponding rates in the chemotherapy-alone group were 37.0%, 13.9%, and 2.5%, respectively.

In the phase III KEYNOTE-407 trial (NCT02775435), 559 treatment-naive patients with metastatic squamous NSCLC received carboplatin (AUC 6) and paclitaxel (200 mg/m²) every 3 weeks or weekly nab-paclitaxel (100 mg/m²), plus pembrolizumab (200 mg every 3 weeks) or placebo for 4 cycles (each 3 weeks), followed by single-agent pembrolizumab (200 mg every 3 weeks) or placebo for up to 31 cycles, for a potential total of 35 cycles.&nbsp;

After the initial 4 cycles, patients randomized to the placebo arm were allowed to cross over to receive pembrolizumab for the potential additional 31 cycles. The coprimary endpoints were OS and PFS. A key secondary endpoint for the study was ORR.

Two-hundred seventy-eight patients were treated in the pembrolizumab cohort and 281 patients received treatment in the chemotherapy-alone arm. In the pembrolizumab arm, 121 patients remained on treatment and 157 had discontinued. The primary reasons for discontinuing were progressive disease (n = 99) and adverse events (AEs; n = 48). In the chemotherapy-alone arm, 72 patients remained on treatment, with 208 having discontinued, primarily due to progression (n = 166) and AEs (n = 25).

Patient characteristics were well balanced at baseline between the 2 arms. In the pembrolizumab arm, the median age was 65.0 years (range, 29-87), 79.1% of patients were men, 73.7% had an ECOG performance status of 1, 7.2% had stable brain metastases, and 92.1% were current/former smokers. Additionally, 60.8% received paclitaxel as their taxane, 6.1% had prior thoracic radiation, and 1.8% had prior (neo)adjuvant therapy.

PD-L1 status was measured by tumor proportion score (TPS). In the pembrolizumab arm, 34.2%, 37.1% and 26.1% had a PD-L1 TPS status of <1%, 1%-49%, and &ge;50%, respectively. The corresponding rates in the placebo arm were 35.2%, 37.0%, and 26.0%, respectively.

The HR for OS was 0.61, 0.57, and 0.64 favoring the pembrolizumab arm in the TPS <1%, <1%-49%, and &ge;50% subgroups, respectively. Across the same 3 subgroups, the HR for PFS favoring the pembrolizumab arm was 0.68, 0.56, and 0.37, respectively.

The median treatment duration was 6.3 months in the pembrolizumab arm compared with 4.7 months in the placebo arm. Grade 3/5 all-causes AEs occurred in 69.8% versus 68.2% of the 2 arms, respectively. Treatment-related AEs (TRAEs) led to discontinuation in 23.4% of the experimental arm versus 11.8% of the control arm. Grade 3/5 immune-mediated AEs and infusion reactions occurred in 10.8% versus 3.2% of the 2 arms respectively. Overall, TRAEs led to death in 3.6% versus 2.1% of the 2 arms, respectively.&nbsp;

Based on these findings, Merck (MSD), the manufacturer of pembrolizumab, submitted a supplemental biologics license application to the FDA for the use of pembrolizumab in combination with standard chemotherapy as a treatment for patients with metastatic squamous non—small cell lung cancer.

Reference:

Paz-Ares LG, Luft A, Tafreshi A, et al. Phase 3 study of carboplatin-paclitaxel/nab-paclitaxel (Chemo) with or without pembrolizumab (Pembro) for patients (Pts) with metastatic squamous (Sq) non-small cell lung cancer (NSCLC).J Clin Oncol. 2018;36 (suppl; abstr 105).