, according to researchers.
They conducted a phase 2 trial to investigate whether one-third of the maximum tolerated dose of erlotinib could maintain sufficient plasma concentration of the drug while avoiding the adverse effects of higher doses. The results were published in JAMA Oncology.
Erlotinib and other epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have demonstrated efficacy in elderly patients with EGFR-positive NSCLC, according to study author Shingo Miyamoto, MD, of Japanese Red Cross Medical Center in Tokyo, and colleagues.
“With the increasing number of elderly patients with cancer, many of whom also have significant comorbidities, there is a considerable value in investigating whether EGFR-TKIs are effective for the frail population,” the authors wrote. They also noted that it is “difficult to identify the appropriate dose of molecular-targeted drugs.”
With this in mind, Dr. Miyamoto and colleagues conducted a single-arm, phase 2 trial of low-dose erlotinib in 80 chemotherapy-naive frail or elderly patients with EGFR-positive NSCLC. Frailty was defined by age and the Charlson Comorbidity Index. The patients’ median age was 80 years (range, 49-90 years).
Patients received erlotinib at 50 mg per day, which is one-third of the established maximum tolerated dose, for 4 weeks. Then, they were evaluated with radiologic imaging. Treatment continued until disease progression or unacceptable adverse events. Dosing was modified by treatment response or by adverse events.
Results
At last follow-up, 7 of the 80 patients were still receiving low-dose erlotinib. Reasons for discontinuation were disease progression (n = 60), patient request (n = 6), adverse events (n = 4), and death (n = 3).
The overall response rate was 60%, and the disease control rate was 90%. The researchers measured plasma erlotinib concentration in 48 patients and found it did not correlate with response.
The median progression-free survival was 9.3 months, and the median overall survival was 26.2 months.
Ten patients had erlotinib temporarily suspended because of adverse events. Five patients had their dose reduced to 25 mg because of adverse events, including oral mucositis, paronychia, erythema multiforme, diarrhea, and anorexia.
Two patients discontinued treatment because of adverse events. One patient had a cutaneous ulcer and bone infection. The other had oral mucositis.
Dr. Miyamoto and colleagues concluded that, “low-dose erlotinib was associated with efficacy and safety in frail patients with EGFR mutation–positive lung cancer. More research on the dosing strategy of target-based drugs is warranted, especially in frail patients in the real-world setting.”
Less is more
Sometimes, less can be more, said Mellar P. Davis, MD, an oncologist and section head of the palliative care department at Geisinger Medical System in Danville, Penn., who was not involved in this study.
Dr. Mellar P. Davis
“Why do patients benefit from small doses? It may be that there are fewer drug interruptions over time and patients are able to stay on schedule,” Dr. Davis said. “It may also be that erlotinib clearance is reduced in the elderly and comorbid patient. The reduced dose may, in fact, be the ‘therapeutic’ dose in this special population.”
Plasma levels were frequently in therapeutic ranges in this study, but patients who had subtherapeutic plasma levels also responded to therapy, Dr. Davis pointed out. The lower dose was shown to maintain sufficient concentrations of the treatment while reducing adverse effects.
However, Dr. Davis noted, this was not a randomized trial. “It is always a risk hedging bets on single-arm trials,” he said. “Randomized trials often prove phase 2 single-arm trials wrong.”
He added that quality-of-life measures are absent from the study. Erlotinib is a palliative drug with side effects, Dr. Davis noted.
“Control of cancer and cancer regression should improve symptoms and quality of life when balanced against treatment toxicity,” he said. “In this study, I would have thought that symptom improvement, performance score, and quality of life would have been the primary outcome or the co-primary outcome with disease control.”
Should a randomized, controlled trial of low-dose erlotinib be conducted in the frail/elderly population? “If one believes trials should be quantitatively based, the answer would be no,” Dr. Davis said. “Responses may be the same, and it would be expensive to prove that low-dose erlotinib is the same as standard doses when comparing survival.”
However, if one is interested in quality of life, particularly in this growing population, a trial that incorporated quality-of-life measures would make more sense, according to Dr. Davis. “For if one can achieve less toxicity and treat more patients and get the same duration of clinical benefit, then less will be more,” he concluded.
Dr. Davis reported having no conflicts of interest. Study authors disclosed relationships with Astellas Pharma, AstraZeneca, Bristol-Myers Squibb, and many other companies. Erlotinib is manufactured for OSI Pharmaceuticals, an affiliate of Astellas Pharma, and distributed by Genentech, a member of the Roche Group.
The study was supported by the Japan Agency for Medical Research and Development.
SOURCE: Miyamoto S et al. JAMA Oncol. 2020 May 14; e201250. doi: 10.1001/jamaoncol.2020.1250.