Toxicities Associated with Targeted Therapy and Immunotherapy Underreported in Published Studies

TON - January 2017, Vol 10, No 1 - Supportive Care
Alice Goodman

Copenhagen, Denmark—Most oncologists’ knowledge about toxicities associated with newer therapies comes mainly from clinical trials, but publications of clinical trial safety results may be misleading, according to a study presented by Paolo Bossi, MD, Medical Oncologist, Head & Neck Unit, Istituto Nazionale dei Tumori, Milan, Italy, at the recent European Society for Medical Oncology Congress. The study investigators found suboptimal reporting of adverse events in studies of immunotherapy and targeted therapy published over the past 15 years. In particular, the investigators identified suboptimal reporting of recurrent or late toxicities and the duration of adverse events associated with immunotherapy and targeted therapy.

“Reporting adverse events from clinical trials with new agents is a crucial point, as this will inform physicians and patients regarding the safety profile of that drug and what to expect when starting this therapy in a new patient in everyday clinical practice,” said Dr Bossi.

The study was based on a review of 81 clinical trials of targeted therapies and immunotherapies that were approved by the FDA from 2000 to October 2015 for the treatment of solid tumors in adult patients. Each study was assessed using a 24-point score based on the Consolidated Standards of Reporting Trials guidance.

The clinical trials were conducted mainly in patients with colorectal, lung, and breast cancers, and melanoma and involved >45,000 patients; 95% of the trials were conducted in advanced cancers. The experimental drug was studied as a single agent in 51% of cases, and in combination with chemotherapy in 32%.

The investigators found that >90% of the trials had poor scores related to reporting recurrent and late toxicities, as well as in reporting the duration of adverse events; 86% did not adequately report the time the adverse events occurred, and 75% restricted reporting to adverse events that occurred at a frequency above a fixed threshold.

More than 50% of the reported studies had limitations in the way adverse events were presented, in describing toxicities leading to treatment cessation, and in the follow-up interval assessments. One-third of the studies failed to report dose reductions because of adverse events.

“Toxicities of targeted agents and immunotherapy are obviously different from the toxicities we are used to observing and treating due to chemotherapy, and there are some aspects of the toxicities of these newer agents that we are not so well-informed about,” Dr Bossi said.

The 3 axes of reporting toxicities include frequency, severity, and duration of an adverse event. The duration of an adverse event is not typically considered when a new drug comes to market, he noted.

Dr Bossi was encouraged to see a trend toward improved reporting of adverse events in recent years. New instruments are available to help physicians improve the quality of reporting adverse events and discuss potential toxicities with their patients.

He cited the National Cancer Institute’s PRO-CTCAE form, a patient-reported outcome instrument for reporting adverse events.

“[This] will allow physicians to collect symptoms as reported by the patients, considering also the severity, intensity, and influence of the symptoms on their quality of life,” Dr Bossi said.

Commenting on this study, Nathan Cherny, MD, Head of Palliative Medicine, Shaare Zedek Medical Center, Jerusalem, noted that evidence shows clinicians underreport adverse events as well as their severity, compared with patient reports.

“These findings lend further support to the proposal to radically reevaluate the collection and reporting of adverse event data to give weighting to patient-reported data,” Dr Cherny said.

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Last modified: February 2, 2017