CON: No Data Supporting OS Benefit
Offering counterpoint to Dr. Felip’s argument, Jordi Remon Masip, MD, PhD, of Gustave Roussy cancer treatment center in Villejuif, France, said that the currently available evidence suggests that MRD helps identify a high-risk population, but that its utility in the clinic is still uncertain.
“Today, I am a believer that we need prospective clinical trials, but one of the most important points today is to elucidate if the minimal residual disease is just prognostic or whether we really can use this minimal residual disease for making treatment decisions, not only escalating [but] also de-escalating treatment strategies in early stage non–small cell lung cancer,” he said.
Risk stratification may help to identify those patients who can most benefit from intensive therapy, but it appears to be much more difficult to risk stratify patients with early stage NSCLC, he said, pointing to the International Tailored Chemotherapy Adjuvant (ITACA) trial, a phase III multicenter randomized trial comparing adjuvant pharmacogenomic-driven chemotherapy versus standard adjuvant chemotherapy in patients with completely resected stage II-IIIA NSCLC. In this study, chemotherapy customized to individual patients according to molecular diagnostic analysis after surgery did not improve overall survival outcomes.
Dr. Masip said that as a clinician he would like to have any reliable tool that could help him to decide which patients need more therapy and which can do well with less.
He agreed that MRD-positivity as signaled by ctDNA after surgery or by a tumor-informed method correlates with poor prognosis, but he noted that MRD status depends on clinical characteristics such as sex, smoking status, age, stage, tumor size, histology, and many other factors that need to be taken into account if the assay is to have value in clinical practice.
“It’s true that the minimal residual disease may capture a poor prognostic population. However, even if we apply the minimal residual disease in our daily clinical practice, we can only capture, or we can only rescue 20% of the patients with the wild type or oncogenic early stage non–small cell lung cancer,” he said.
In addition, as Dr. Felip acknowledged, the negative predictive value of MRD is not infallible, with a 63% false negative rate compared with only a 2% false-positive rate.
“Half of the patients with the recurrence of the disease have a very, very low circulating tumor DNA, and the techniques are not sensitive enough to capture this minimal residual disease,” Dr. Masip said.
It would also be a mistake to forgo giving adjuvant therapy to those patients deemed to be MRD-negative on the basis of ctDNA, given the high false-negative rates, he said.
Oncologists also have to put themselves in their patients’ shoes:
“If our patients accept that with minimal residual disease I can only improve the disease-free survival without improving the overall survival, they would accept having less toxicity but the same survival that they would if they started the treatment later, and also what would happen if the patient is randomized to no adjuvant treatment because the minimal residual disease is negative, and some months later there is a recurrence of disease?” Dr. Masip said.
“I think we need more prospective data, but we really, really need a more sensitive test to avoid or to decrease the percentage of patients with false-negative results, and also we need very motivated patients that would accept to be randomized to de-escalate treatment strategies,” he concluded.
Dr. Felip disclosed advisory or speakers bureau roles for AbbVie, Amgen, AstraZeneca, Bayer, Beigene, Boehringer Ingelheim, Bristol Myers Squibb, Daiichi Sankyo, Eli Lilly, F. Hoffman-La Roche, Genentech, Gilead, GlaxoSmithKline, Janssen, Medical Trends, Medscape, Merck Serono, MSD, Novartis, PeerVoice, Peptomyc, Pfizer, Regeneron, Sanofi, Takeda, and Turning Point Therapeutics. She has served as a board member of Grifols. Dr. Masip disclosed research support from MSD, AstraZeneca, and Sanofi, and other financial relationships with AstraZeneca, Sanofi, Takeda Roche, and Janssen.