Truqap Side Effects Linked to Discontinuation Risks, FDA Staffers Warn

Agency experts say they see little benefit from combining Truqap with Zytiga to treat prostate cancer, after clinical trials have revealed high toxicity levels and patient deaths.

Federal drug safety experts are warning that Truqap may expose prostate cancer patients to serious toxicity risks while offering limited treatment benefits.

Drug reviewers with the U.S. Food and Drug Administration (FDA) released a briefing document ahead of an April 30 meeting of the agency’s Oncologic Drugs Advisory Committee. The report comes as the committee prepares to weigh Truqap’s potential use in a new combination cancer treatment.

Truqap Approval

Truqap (capivasertib) was first approved by the FDA in 2023 as a breast cancer treatment, used in combination with fulvestrant for certain patients whose cancer has become metastatic, meaning it has spread to other parts of the body. AstraZeneca is now seeking FDA approval to expand use of the drug as a prostate cancer treatment, in combination with Johnson & Johnson’s Zytiga (abiraterone).

The request is being reviewed by an FDA advisory committee, which is made up of outside scientists, physicians and other health experts who evaluate drug approval questions and make recommendations to the agency. While the committee’s votes are not binding, the FDA often follows the advice of its advisory panels when deciding whether to approve new uses for medications.

Truqap Toxicity Risks

Before the meeting, FDA staffers submitted their own review of the drug, raising reservations about its safety and effectiveness as part of the prostate cancer treatment combo. The reviewers found the evidence of its effectiveness unconvincing, questioning the techniques researchers used during clinical trials to reach their conclusions.

One of the end goals of the clinical trials involved measuring the time between the end of treatment and the patient’s need for chemotherapy. However, reviewers noted that numerous factors which have nothing to do with the drug’s effectiveness could delay such treatments, including financial issues and chemotherapy drug availability.

The document points out that all similar prostate cancer medications showed signs of higher effectiveness before the agency approved them.

Additionally, the FDA raised concerns about Truqap’s level of toxicity, indicating that during a Truqap clinical trial patients took the drug for only 16.8 months, while those given placebos took them for 18.6 months. The researchers then compared the outcomes as if both groups had taken the medications for similar durations.

However, the reviewers noted that the reason the Truqap group had a shorter use duration overall was due to the large number of patients who discontinued the study due to adverse side effects. The drug’s application notes that these patients were generally able to continue taking Zytiga if they suffered adverse events from Truqap use.

“While the FDA agrees with the Applicant that treatment with capivasertib did not compromise exposure to abiraterone overall, the high discontinuation rate and shorter duration of exposure to capivasertib compared to placebo suggest that capivasertib was not well-tolerated.”

– Combined FDA and Applicant ODAC Briefing Document

In their summary, the FDA reviewers warned that the benefits of adding Truqap to Zytiga, which is an established and well-tolerated prostate cancer drug, could not be distinguished from the effects of Zytiga alone. 

Additionally, they warned that the risk of Truqap’s toxicity, which they say contributed to some patient deaths, needs to be considered in comparison to the seemingly small potential benefit.

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