GlaxoSmithKline’s Zejula has opened up a new front in its challenge against AstraZeneca and Merck’s Lynparza, the established leader in the PARP inhibitor class.
Wednesday, the FDA approved Zejula in advanced ovarian, fallopian tube or primary peritoneal cancer patients who have undergone at least three prior chemo regimens, as long as their tumors have homologous recombination deficiencies, GSK said.
Both Lynparza and Clovis Oncology’s Rubraca boast go-aheads in treating advanced ovarian cancer, but only BRCA-mutated cases—for which PARP inhibitors are traditionally known to work. Now, GSK’s Zejula has become the first of the group green-lighted to treat tumors in the HRD-positive group—rather than stave off cancer's return in the maintenance setting—marking an early win for CEO Emma Walmsley’s pivot to oncology with the $5.1 billion acquisition of Zejula developer Tesaro.
The FDA based its decision on results from the phase 2 Quadra trial, which GSK said was the largest of its kind. In the study, Zejula triggered a response in 24% of patients, lasting for a median 8.3 months. Researchers saw benefits across various subpopulations, including BRCA-/HRD+ platinum-sensitive disease.
Zejula’s first FDA green light was for preventing cancer progression in patients whose tumors have come back and have responded to platinum-based chemo. Both that 2017 nod in the recurrent maintenance setting and the current one for late-line treatment cover patients beyond those with a BRCA mutation.
Since its initial 2014 approval, Lynparza has established a leadership position in the PARP class. While the three drugs are battling out in the recurrent ovarian cancer maintenance setting—regardless of BRCA status—Lynparza jumped into first-line maintenance in late 2018, though only in the BRCA-mutated group. With that addition, Lynparza sales in the third quarter almost doubled year over year to $327 million, 8% above analysts’ expectations.
However, all three PARP drugmakers with ovarian cancer nods are chasing a larger first-line maintenance go-ahead for all ovarian cancer patients, and Zejula and Lynparza have already shown promise.
In women who had responded to one round of platinum chemo, Zejula cut the risk of disease progression or death by 38% across all ovarian cancer patients in the phase 3 Prima study, GSK unveiled at this year’s European Society for Medical Oncology annual meeting in September. Even among those with neither BRCA nor HRD markers, the reduction reached 32%.
As for AstraZeneca and Merck, the pair showed a combo of Lynparza and Roche’s Avastin could cut the risk of disease progression or death by 41% in the same setting, also regardless of BRCA mutation status.