GENEVA – Treatment with osimertinib leads to clinically meaningful responses in about half of patients with epidermal growth factor receptor (EGFR) T790M–positive non–small cell lung cancer (NSCLC) who have asymptomatic leptomeningeal metastases, according to a post hoc analysis of patients from multiple AURA studies.
This conclusion aligns with previous encouraging findings delivered by the BLOOM trial, with the notable caveat that AURA patients received the Food and Drug Administration–approved dose of 80 mg osimertinib daily, instead of 160 mg, as given to BLOOM patients, reported lead author, of Samsung Medical Center in Seoul, South Korea, and her colleagues.
At the European Lung Cancer Congress, invited discussantof the Dana-Farber Cancer Institute in Boston, provided additional background for the study. “Leptomeningeal disease is really a devastating complication for our patients with lung cancer,” Dr. Jänne said, noting that effective treatments have been historically lacking; apart from osimertinib, other treatment strategies have included whole brain radiation therapy, high-dose pemetrexed, and pulsatile erlotinib, which were largely based on anecdotal evidence. Like other next-generation tyrosine kinase inhibitors, osimertinib stands apart from older agents because of its greater ability to penetrate the blood-brain barrier.
The present, retrospective analysis involved 22 patients with advanced, EGFR T790M–positive NSCLC with asymptomatic leptomeningeal metastases (LM) that was radiographically detected by blinded independent review. Patients received 80 mg osimertinib daily after progressing on another EGFR tyrosine kinase inhibitor. Follow-up brain scans were evaluated using Response Assessment in Neuro-Oncology LM criteria. Median overall survival was determined, as were progression-free survival, duration of response, and objective response rate, with these latter parameters analyzed specifically for LM disease.
Demographically, the patient population was consistent with previous AURA trials, with a predominance of Asian (82%) and female (59%) patients. Patients received treatment for a median of 7.3 months. Analysis showed that slightly more than half of patients (55%) responded to therapy, with an even split between partial (27%) and complete responders (27%). Median progression-free survival reached almost 1 year (11.1 months), while overall survival exceeded a year and a half (18.8 months), with a 1-year overall survival rate of 65%. Duration of response data are still immature. Graphical longitudinal analysis showed comparable responses between the AURA and BLOOM trials, suggesting that an 80-mg dose is likely to provide a similar efficacy to a 160-mg dose, Dr. Ahn said, although she also urged a cautionary interpretation because of study design.
Dr. Ahn described the survival statistics as “encouraging” at the meeting presented by the European Society for Medical Oncology, as the outcomes were better than those typically seen in historical controls.
Discussing these findings, Dr. Jänne suggested that the patient assessment criteria were “pretty subjective in nature.”
“You could get a score of plus one or minus one if the scans are kind of better or kind of worse,” Dr. Jänne said. “There’s really no objective criteria there.” He noted that imaging results may not reflect clinical impact of LM disease, and suggested that additional assessment criteria would have been welcome, such as assessments involving neurologic status or cerebrospinal fluid characteristics, both of which were included in the BLOOM trial.
“The real question comes, when we’re facing someone with leptomeningeal disease, is 80 milligrams as effective as 160 milligrams?” Dr. Jänne asked. “I don’t think we have the answer to that because the [AURA and BLOOM] studies are different, including different endpoints, and they’re not comparative.” He also noted that, in the United States, when met with LM disease progression, clinicians commonly increase the osimertinib dose from 80 mg to 160 mg; however, “it is without any data,” and warrants an actual clinical study.
The study was funded by AstraZeneca. The investigators reported financial relationships with Novartis, Pfizer, Roche, and others.
SOURCE: Ahn MJ et al. ELCC 2019, .