The Appeal

Do Cancer Drugs Work Safely for People with Obesity? Maybe

At a time when nearly half of the U.S. population is living with obesity, this should be an easy question to answer. Obesity clearly causes some forms of cancer and as the prevalence of obesity is rising, patterns of cancer prevalence are shifting, too. So, yes, we should be able to say with great confidence that cancer drugs will work safely for people living with obesity. But we can’t. Because there are issues that need attention.

Widely Different Effects of Obesity on Cancer Drugs

Scientists from the University of North Carolina and the U.S. Food and Drug Administration explain these issues with a new paper in the Journal of Clinical Pharmacology. The bottom line is pretty straightforward. The information on safe and effective doses of cancer drugs in people with obesity is inadequate.

Roughly 40% of people with obesity receive inadequate doses for an optimal clinical outcome. Because obesity can affect the kinetics and dynamics of different cancer drugs in “widely different” ways, they say better studies are necessary to ensure that people with obesity will receive safe and effective anticancer therapy doses.

Drug Interactions

Drug interactions can add to the problem. For instance, fungal infection can be a significant complication of cancer therapy. One of the drugs commonly used to treat these infections is posaconazole (Noxafil). But this drug interacts in potentially dangerous ways with some anticancer drugs and it lingers longer in the body of a person with obesity. So unless an oncologist accounts for this when resuming cancer therapy, a patient with obesity and cancer can be at risk for a serious or even life-threatening drug interaction.

This problem is made worse because labeling for posaconazole offers inadequate information on dosing and half-life in people with obesity. Companies who make this drug are failing in their duty to warn about a potentially life-threatening issue.

A Failure to Protect People with Obesity

This is a missed opportunity – a failure to protect the health and safety of people with obesity. Where the information already exists to guide better, safer dosing for drugs used in cancer, FDA and pharmaceutical companies should move immediately to include it.

For new drugs, FDA should set a higher bar for precision medicine in cancer care for people living with obesity.

Click here for the new publication in the Journal of Clinical Pharmacology and here for perspective on how assessments of drug safety and effectiveness keep failing people with obesity. For more on the issue with posaconazole, click here.

The Appeal, painting attributed to Titian, Giorgione, and Sebastiano del Piombo / Wikimedia Commons

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November 18, 2023