Long-term survival rates for immunotherapies could be misinterpreted

Yu Shyr, PhD, Harold L. Moses Chair of Cancer Research and Chair of the Division of Biostatistics at Vanderbilt University Medical Center Credit: Vanderbilt University Medical Center

Immune checkpoint inhibitors have changed cancer care so much that the popular Cox proportional hazards model provides misleading estimates of treatment effect, according to a new study published April 15 in JAMA Oncology.

The study “Development and Evaluation of a Method for Correcting Misinterpretations of Clinical Trial Results with Long-Term Survival” suggests that some of the published survival data for these immunotherapies should be re-analyzed for possible misinterpretations.

The study’s lead author, Yu Shyr, Ph.D., of the Harold L. Moses Chair in Cancer Research and Chair of the Department of Biostatistics at Vanderbilt University Medical Center, and colleagues Chih-Yuan Hsu, Ph.D., and Emily Lin, MD, Ph.D. proposed an adaptation to convert the inappropriate Cox proportional hazards model into the appropriate healing model. The fitting uses the Cox-TEL method (Cox PH-Taylor extension for long-term survival data).

“The Cox Proportional Hazards Model has emerged as the preferred choice for survival analysis in clinical trials for many reasons, including its robustness. However, researchers should not blindly use it in immunotherapy trials,” Shyr said.

“Since the proportional hazard assumption of the model is clearly violated in some immunotherapy studies, the results and conclusions based on this model are inaccurate and misleading. We wanted to develop an approach that not only corrects the exposure rate of the proportional Cox hazard model. We believe, however, that Cox-TEL is being used extensively to avoid misinterpretation of clinical trials with long-term survival. “

The research team started its work due to the frequent observation of long tails and crossovers in survival curves with immune checkpoint inhibitors. These observations violate the proportional hazard assumption in the widely used Cox proportional hazards model. The researchers examined simulated data and real data from published studies with immune checkpoint inhibitors. When comparing the Cox proportional hazards model with the Cox-TEL fitting method, they found that the Cox-TEL fitting method was more accurate in assessing long-term survival. The Cox-TEL adaptation is user-friendly and freely available as a package in the R statistics software.

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More information:
JAMA Oncology (2021). DOI: 10.1001 / jamaoncol.2021.0289 Provided by Vanderbilt University Medical Center

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