- A new analysis of the SOLAR-1 study of Novartis' alpelisib showed the drug, when paired with hormone therapy, improved median progression free survival (PFS) by 11 months for PIK3CA-mutated, HR-positive, HER2-negative advanced breast cancer patients, compared to 6.8 months for patients only receiving the hormone therapy.
- Topline results from the Phase 3 study came in August, while the more thorough data were presented at the 2018 San Antonio Breast Cancer Symposium. In addition to the numbers, Novartis highlighted how PFS benefit was observed regardless of whether researchers identified a patient's PIK3CA mutation through a tumor tissue test or a type of liquid biopsy known as circulating tumor DNA test.
- The Swiss pharma said the results therefore hint at "the potential viability of using liquid biopsies to identify PIK3CA mutation status ..." Novartis estimates around 40% of the HR-positive advanced breast cancer population have a PIK3CA mutation and may benefit from targeted therapy.
Cancer biopsies used to mean invasive testing, anything from fine needle aspiration to open surgery, and all of these carry risks. There are concerns, for instance, that the needle aspiration process could potentially "seed" new tumors. Meanwhile, surgery carries risks of infection.
The growing research into liquid biopsies, both in industry and academia, could improve cancer diagnosis, making it simpler, safer, more effective and less invasive. These tests pick up biomarkers of cancer, including circulating tumor DNA, exosomes and circulating tumor cells — all from a blood draw. One of their more common uses is to guide treatment selection in late-stage cancer, yet liquid biopsies could also play a role in screening, early diagnosis and post-treatment monitoring to give an early heads-up about risk of relapse.
SOLAR-1 is the first breast cancer trial to demonstrate the potential role of liquid biopsies. Novartis has signed deals with Qiagen and Foundation Medicine to develop companion diagnostics for alpelisib that use both tumor tissue and plasma samples. The partnership with Qiagen, announced Thursday, will encompass DNA extraction, mutation detection and final reporting.
"There is an unmet medical need for improved treatment options in patients living with HR-positive, HER2-negative advanced breast cancer with a PIK3CA mutation. Currently, no FDA-approved drugs are available on the U.S. market to specifically target this mutation in breast cancer," said Jonathan Arnold, Qiagen's head of oncology and precision diagnostics, in a Dec. 6 statement.
The SOLAR-1 trial will continue in order to evaluate the secondary endpoints such as overall survival. Discussions are underway with regulatory authorities.
If approved, the drug would enter a busy marketplace for advanced breast cancer, its activity in PIK3CA mutated HR+/HER2- patients, as well as the availability of an associated companion diagnostic, could give it an edge.