- Novartis said Thursday it will start talks with regulators on the merits of its experimental breast cancer drug alpelisib, after initial results from a Phase 3 study found treatment with the PI3K inhibitor helped delay disease worsening or death in a type of advanced breast cancer.
- In the so-called SOLAR-1 study, alpelisib combined with hormone therapy improved progression-free survival over hormone therapy alone in patients with metastatic breast cancer positive for hormone receptors but lacking a protein known as HER2.
- Alpelisib targets a signaling pathway known as PI3K that's frequently mutated in patients with this type of breast cancer. But previous efforts, including by Novartis and fellow Swiss pharma Roche, to develop a P13K inhibitor for breast cancer patients have fallen short of success.
PI3K inhibitors have had a mixed track record.
Gilead Sciences won the first approval for the drug class back in 2014 with Zydelig (idelalisib). Since then, Bayer last fall secured a U.S. OK for its Aliqopa (copanlisib) in third-line follicular lymphoma.
But uptake of Zydelig has remained tepid amid safety concerns and strong competition from AbbVie and J&J's Imbruvica (ibrutinib). And other drugmakers have halted development work on more than a dozen experimental P13K blockers.
Most recently, Roche decided against pursuing further testing of taselisib after disappointing results from its SANDPIPER study in breast cancer patients. While the drug showed a modest 30% reduction in the risk of disease worsening or death over fulvestrant, nearly a fifth of patients given the study drug discontinued treatment due to side effects.
Novartis' study results appeared to offer a counterpoint to those of its Swiss rival, although full details of the trial won't be available until an unspecified future medical congress.
SOLAR-1 enrolled 572 patients with HR+/HER2- advanced breast cancer and a specific genetic mutation involving the PI3K pathway. About 40% of breast cancer patients who test positive for hormone receptors and negative for HER2 have the PI3KCA mutation that alpelisib targets, according to Novartis.
Adverse events with alpelisib were consistent with previous testing and the SOLAR-1 study will continue to assess the drug's effect on secondary endpoints.
"[Alpelisib] is the only alpha-specific PI3K inhibitor and the first one to show potential increased benefit and acceptable tolerability for patients," said Samit Hirawat, head of Novartis' global oncology drug development, in an Aug. 23 statement.