Advances in precision medicine help refine – and redefine – cancer care

— Susan London

First-line immunotherapy boosts survival in NSCLC patients

Key clinical point Many patients with previously untreated NSCLC could benefit from first-line therapy with the checkpoint inhibitor pembrolizumab. Major finding In all patients with expression of PD-L1 on 1% or more of tumor cells, OS was 16.7 months with pembrolizumab, compared with 12.1 months for chemotherapy. Study details Randomized phase 3 trial of 1,274 patients with advanced or metastatic NSCLC. Funding Merck, the maker of the study drug, funded the study. Disclosures Dr Lopes disclosed institutional research funding from Merck Sharp & Dohme, EMD Serono, and AstraZeneca. Dr Heymach disclosed stock/ownership in Bio-Tree and Cardinal Spine, a consulting or advisory role for Abbvie, ARIAD, AstraZeneca, Boehringer Ingelheim, Bristol-Myers Squibb, Calithera Biosciences, Genentech, Medivation, Novartis, Oncomed, and Synta, and institutional research funding from AstraZeneca. Dr Gandhi reported having no relevant disclosures. Source Lopes G et al. ASCO 2018, abstract LBA4. https://meetinglibrary.asco.org/record/165950/abstract

Pembrolizumab as first-line treatment of advanced non–small-cell lung cancer (NSCLC) offered longer OS with better tolerability compared with chemotherapy, results of the Keynote-042 phase 3 randomized trial show.

In 1,274 patients with advanced, previously untreated NSCLC with expression of the PD-L1 on 1% or more of tumor cells, median OS after a median follow-up of 12.8 months was 16.7 months for patients treated with pembrolizumab monotherapy, compared with 12.1 months for patients treated with either paclitaxel or pemetrexed plus carboplatin, reported lead author Gilberto Lopes, MD, of the Sylvester Comprehensive Cancer Center at the University of Miami.

The survival benefit for immunotherapy was even greater for patients with higher levels of PD-L1 expression: 20 versus 12.2 months for patients with PD-L1 expression of 50% or greater, and 17.7 versus 13 months for patients with PD-L1 expression of 20% or greater, Dr Lopes noted.

For all 3 PD-L1 expression groups, the median duration of response was 20.2 months, compared with 10.8-8.3 months for patients in the chemotherapy arm.

“These are responses that are unlike anything that we have seen with chemotherapy in the past for non–small-cell lung cancer,” Dr Lopes said at a briefing before his presentation. “In addition to that, and probably more importantly, patients had fewer adverse events [with pembrolizumab]. Overall, about 60% had any treatment-related adverse event with pembrolizumab, versus 90% with chemotherapy,” he added.
 

‘A true milestone’

ASCO expert John Heymach, MD, PhD, of the University of Texas MD Anderson Cancer Center in Houston, said at the briefing that the study was “a true milestone for the field, because now, for the first time, we can say that in non–small-cell lung cancer patients receiving first-line therapy, the vast majority can receive immunotherapy with pembrolizumab instead of chemotherapy.”

He noted that an earlier study, Keynote-024, showed that pembrolizumab significantly improved progression-free survival in patients with tumors expressing PD-L1 on at least 50% of cells compared with standard platinum-based chemotherapy (10.3 vs 6 months).

“This more than doubles that population that can start immunotherapy as a first-line treatment, assuming the [Food and Drug Administration] modifies the label in accordance with this study,” he added.

The Keynote-042 investigators enrolled 1,274 patients with locally advanced or metastatic NSCLC, and randomly assigned them to receive either a maximum of 35 cycles of pembrolizumab 200 mg every 3 weeks, or the investigators’ choice of not more than 6 cycles of either paclitaxel–carboplatin or pemetrexed–carboplatin, with optional pemetrexed maintenance for patients with nonsquamous histologies only.

The randomization was stratified by region (Asia vs non-East Asia), Eastern Cooperative Oncology Group performance status 0 or 1, squamous versus nonsquamous histology, and PD-L1 expression, or TPS (tumor proportion score) greater than 50% versus 1%-49%.

As noted before, the primary endpoint of OS in all patients with a TPS of 1% or greater was met, with respective median OS in the pembrolizumab versus chemotherapy groups of 16.7 and 12.1 months, translating into an HR favoring pembrolizumab of 0.81 (P = .0018). Respective hazard ratios for the TPS 20% or greater and TPS 50% or greater groups were 0.77 (P = .0020) and 0.69 (P = .0003).

At 12.8 months of median follow-up, 13% of patients assigned to pembrolizumab were still on the drug, and 4.3% of patients were receiving maintenance pemetrexed.

Treatment-related adverse events of any grade occurred in 399 of 636 patients assigned to pembrolizumab (62.7%), compared with 553 of 615 patients assigned to chemotherapy (89.9%). Grade 3 or greater events occurred in 17.8% and 41% of patients, respectively. There were 13 deaths related to therapy in the pembrolizumab arm (2.0%), and 14 in the chemotherapy arm (2.3%). Adverse events leading to discontinuation were similar between the groups, at 9% and 9.4%, respectively.

There were more immune-mediated adverse events in the pembrolizumab arm than in the chemotherapy arm (27.8% vs 7.2%, respectively), and of those, grade 3 or higher events occurred in 8% and 1.5% of patients. There was 1 immune-mediated death, from pneumonitis, in the immunotherapy arm; there were no deaths related to immune-mediated side effects in the chemotherapy arm.

“I really view this as a ‘double whammy’ for patients,” Dr Heymach said at the briefing. “Often advances in survival for our lung cancer patients come at the cost of significant toxicities. Here, by contrast, not only are patients living longer and having a much higher likelihood of prolonged survival in years, often instead of months, but they’re also receiving a treatment that has substantially less toxicity across virtually all measures, and this really impacts the day-to-day life of these patients.”

Leena Gandhi, MD, PhD, of the Perlmutter Cancer Center at New York University, the invited discussant at the plenary, agreed that pembrolizumab improves survival, compared with chemotherapy patients with PD-L1 expression levels greater than 1%, but noted that most of the benefit – as also seen in Keynote-024 – was in those patients whose tumors had high levels of PD-L1 expression.

She emphasized that although PD-L1 is an imperfect biomarker, it should still be used to help select patients for therapy and it may be complementary with tumor mutational burden for more precise treatment selection.

“What we know, and what this study adds to, is that PD-L1 really does define a patient population that could receive benefit from pembrolizumab over chemotherapy. Patients with low or no PD-L1 expression likely should get some type of combination therapy,” she said. “This study extends what we’ve seen from other recent studies, which is that chemotherapy alone is no longer a first-line standard of care in non–small-cell lung cancer.”