Novel Drug Combo Fast Tracked for Advanced Breast Cancer Subset

The Food and Drug Administration (FDA) granted a Fast Track Designation to zotatifin plus Faslodex (fulvestrant) and Verzenio (abemaciclib) for patients with pretreated, estrogen receptor (ER)-positive, HER2-negative advanced or metastatic breast cancer that progressed on or after treatment with an endocrine therapy and a CDK4/6 inhibitor, according to eFFECTOR Therapeutics, the manufacturer of zotatifin.

Fast Track Designations — which are initially requested by the pharmaceutical company developing the drug and then granted by the FDA — establish early and frequent communication between the FDA and the drug company, thereby allowing issues to be addressed sooner. In doing so, therapies for serious conditions and illnesses may be able to hit the market sooner, according to the agency.

"We’re grateful to receive this Fast Track designation from FDA, which is a meaningful milestone for the development of zotatifin and reflects the demonstrated potential for zotatifin in combination with (Faslodex) and (Verzenio) to address unmet needs in ER-positive/HER2-negative breast cancer,” Steve Worland, chief executive officer of eFFECTOR, said in a press release.

The novel drug, zotatifin, works by inhibiting a certain protein (RNA helicase elF4A) whose over expression plays a role in the development of cancer. The treatment was also investigated for its antiviral properties against COVID-19.

Zotatifin is currently being investigated in a phase 1/2 dose escalation and expansion trial that includes and is enrolling patients with ER-positive, HER2-negative breast cancer. According to earlier data that was presented at the 2023 American Society of Clinical Oncology Annual Meeting, in patients who underwent four or more lines of therapy for metastatic disease, 26% of evaluable patients achieved a partial response, meaning that their disease shrunk but did not disappear — all of whom received at least one prior CDK 4/6 inhibitor and Faslodex, as well as one or more lines of chemotherapy.

Now, according to the study’s listing on clinicaltrials.gov, researchers are analyzing:

• Objective response rate, which is the percentage of patients whose disease shrinks or disappears from treatment
• Highest tolerable dose, which will be determined by the occurrence of the first dose-limiting toxicity
• Incidence, type and severity of side effects
• Percent change in the size of targeted tumors
• Time to response
• Duration of response, which is defined as the first objective response until disease progression or death of any cause.

Updated data for patients being treated with zotatifin, Faslodex and Verzenio will be presented at the upcoming San Antonio Breast Cancer Symposium in December 2023.

“We value the opportunities provided by Fast Track designation for frequent interactions with the FDA review team as we advance this development program for zotatifin and look forward to providing further data updates and development plans at the 2023 San Antonio Breast Cancer Symposium,” Worland said.

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