How FDA's pCR guidance may affect new drugs for triple-negative breast cancer
Comments are due next Monday on a draft guidance FDA hopes will spur development of targeted therapies for neoadjuvant triple-negative breast cancer. Companies and researchers are encouraged the agency is endorsing a new surrogate endpoint; however, they caution that a poor understanding of the biology of triple-negative disease is the bigger barrier to developing new drugs for this population.
The draft guidance, issued May 30, proposes the use of pathologic complete response (pCR) as a surrogate endpoint for accelerated approval in the neoadjuvant setting. The guidance defines pCR as complete absence of residual invasive cancer in resected breast tissue and all sampled ipsilateral lymph nodes after drug therapy and surgery.
In neoadjuvant trials, patients receive two to four months of therapy with pCR measured at the point of surgery.
According to the agency's guidance as well as FDA's comments to BioCentury, the proposed randomized, double-blind trials would measure superiority of an experimental agent plus SOC vs. SOC alone by comparing the proportion of patients achieving a pCR.
The studies also would be powered to assess disease-free survival (DFS), which would be included in the trial design as a co-primary endpoint that matures later.
The pCR readout could be available within about 2.5 years of starting the trial to support accelerated approval, and DFS data could be available within about five years of the trial start to support full approval.
FDA's intention is to speed development of drugs with the potential to be curative as demonstrated by a large therapeutic effect in the earliest stage of disease.
No drugs are approved in the U.S. for the neoadjuvant setting. New breast cancer agents are often tested and approved first for patients with relapsed or refractory metastatic disease, followed by approval for earlier disease five to 10 years later.
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