GSK Zejula breast cancer trial halted by ‘Eligibility issues’

GSK’s attempt to track tumor cells on a molecular basis in a phase 3-trial of Zejula for certain types of cancer breast has helped patients detect metastatic disease even before symptoms appear.

GSK’s research was ultimately terminated by the results.

GSK discontinued enrollment “permanently”, in April, for ZEST. This late-stage study, which will begin recruiting 800 patients from 2021, is aimed at patients with HER2-negative, BRCA mutated breast tumors or triple-negative cancers with molecular diseases. GSK stated that the move does not portend any issues with Zejula, but rather reflects “eligibility difficulties” which made enrollment “much harder than previously thought”, GSK .

A GSK spokesperson told me via email that less than 5% of 800 patients had been randomly assigned.

CtDNA refers to DNA fragments . CtDNA refers to DNA fragments released by dying tumors into the bloodstream.

For breast cancer patients to qualify for Zejula in ZEST they must have completed “definitive upfront treatments,” which includes surgery and other neoadjuvant or adjuvant treatments. The patients also had to pass a ctDNA and be free of radiologically detectable cancer.

GSK’s spokesperson said in a statement that “the prevalence” of radiologically detectable metastases among patients with ctDNA positivity was higher than expected.

Before their eligibility to the Zejula study could be confirmed, patients who had a positive ctDNA result were subjected to other screenings, such as a CT scan.

GSK explained that “this allowed us to detect asymptomatic metastatic cancer earlier than we would have normally detected it, as routine CT scans were not the standard care for this population.”

GSK clarified that ZEST’s cancellation does not affect any other ongoing trials of niraparib, the generic name for the drug.

GSK will continue to study Zejula for a variety of tumor types, such as lung, ovarian, and childhood cancers. GSK remains committed to precision technology, such as ctDNA tests, which GSK claims allows patients “access to more personalized treatment decisions.”

As of now, breast cancer patients can choose from competing PARP inhibitors such as Pfizer’s Talzenna or Merck’s and AstraZeneca’s Lynparza.

Zejula has been approved for ovarian, fallopian tubes, and peritoneal carcinoma. GSK said that PARP, a drug developed by the British company GSK, brought in 114 million pounds sterling (£114) worldwide during 2023’s initial quarter.

In November, GSK complied with an FDA request that restricted Zejula’s second-line maintenance indication for ovarian cancer in the U.S. only to patients with germline BRCA mutant. GSK previously pulled Zejula approval for late-line ovarian carcinoma.

According to the earnings report of the company, the first-line growth in Zejula’s U.S. market “more than offsets” any decrease in the second-line setting.