GENEVA – Pembrolizumab monotherapy is as safe and effective in elderly patients with non–small cell lung cancer (NSCLC) as it is younger patients, according to investigators.
They reached this conclusion after analyzing pooled data from 264 patients 75 years or older involved in the KEYNOTE-010, KEYNOTE-024, and KEYNOTE-042 phase 3 trials, reported lead author Kaname Nosaki, MD, of the National Hospital Organization Kyushu Cancer Center in Fukuoka, Japan, and his colleagues.
“Approximately 70% of newly-diagnosed NSCLC cases occur in the elderly, and more than half are locally advanced or metastatic,” the investigators noted in their abstract. Despite this, patients aged 75 years or older are underrepresented in clinical trials, Dr. Nosaki said during a presentation at the European Lung Cancer Conference.
All patients in the three KEYNOTE trials had PD-L1 positive NSCLC, with variations between studies with respect to PD-L1 tumor proportion score (TPS) and dosing regimen. While KEYNOTE-010 and KEYNOTE-042 involved patients with a TPS of at least 1%, KEYNOTE-024 raised the minimum TPS threshold to 50%. KEYNOTE-010 pembrolizumab dose was set at 2 mg/kg or 10 mg/kg, compared with the other two studies, which set a consistent dose of the checkpoint inhibitor at 200 mg.
As with younger patients, higher TPS expression generally predicted better outcomes. Independent of treatment line, elderly patients with a TPS of at least 50% had a hazard ratio of 0.40 in favor of pembrolizumab over chemotherapy, compared with all PD-L1-positive elderly patients, who had a hazard ratio of 0.76.
Generally, adverse events were comparable between age groups, with 68% of elderly patients experiencing at least one treatment-related adverse event, compared with 65% of younger patients. Grade 3 or 4 adverse events were slightly more common among elderly patients than younger patients (23% vs. 16%), with a mild concomitant increase in adverse event–related treatment discontinuations (11% vs. 7%). The rate of immune-mediated adverse events and infusion reactions, however, held steady regardless of age group, occurring in one out of four patients (25%). In contrast with these similarities, almost all elderly patients receiving chemotherapy (94%) had adverse events, compared with two out of three elderly patients receiving pembrolizumab. Rates of grade 3 or 4 adverse events also favored pembrolizumab over chemotherapy (23% vs. 59%).
“These data support the use of pembrolizumab monotherapy in elderly patients more than 75 years old with advanced PD-L1-expressing NSCLC,” Dr. Nosaki concluded.
Invited discussant Sanjay Popat, PhD, of Imperial College London, described the knowledge gap addressed by this study. “If we look at U.S. statistics, we see that lung cancer is the leading cause of death for patients above the age of 80, both for males and females,” Dr. Popat said at the meeting, presented by the European Society for Medical Oncology. “The real question is should this group of patients be getting any form of checkpoint inhibitors at all, and if so, what is the benefit to risk ratio?
“Our patients are getting older, we’re all living slightly longer, and the burden of geriatric oncology is predicted to rise quite markedly with age, so it’s important to get a good feel for how we should be managing our senior population,” he added.
According to Dr. Popat, elderly patients naturally undergo immune senescence, meaning the immune system deteriorates with age, and this phenomenon could theoretically mitigate efficacy of immunotherapies; however, previous studies have not found decreased efficacy among elderly patients. Still, some “so-called elderly population subsets we’ve been analyzing are actually around the median age [of diagnosis with NSCLC],” Dr. Popat said, noting that among these studies, those with wider age ranges offer more reliable data.
“Today we looked at the novel cutoff, this 75-year group cutoff, which I very much welcome,” Dr. Popat said, “because this much more reflects what we see in routine clinical care.”
Regarding the results, Dr. Popat suggested that chemotherapy leads to an “excess of mortality” among elderly patients, “likely due to toxicities,” thereby explaining part of the relative advantage provided by pembrolizumab. Considering these findings in addition to previous experiences with pembrolizumab in the elderly, Dr. Popat said that “if you choose your patient population well, fit patients well enough to go to a trial, they don’t have an excess of toxicities regardless of their age.”
Taken as a whole, the present analysis supports the routine use of pembrolizumab in fit, elderly patients, Dr. Popat said.
The study was funded by MSD. The investigators reported financial relationships with AstraZeneca, Eli Lilly, Taiho, Chugai, and others.
SOURCE: Nosaki et al. ELCC 2019. .