Lilly's breast cancer drug abemaciclib a breakthrough, says FDA

The US FDA has granted breakthrough status for abemaciclib, a breast cancer therapy that has just entered phase III testing.

The designation is a major boost for Lilly, not least because breakthrough status is arguably a tougher objective in breast cancer, which has been relatively well-served by new therapies in recent years than other tumour types.

Abemaciclib has been awarded the status for the treatment of patients with refractory hormone-receptor-positive (HR+) advanced or metastatic breast cancer, on the strength of a phase I trial reported at last year's San Antonio Breast Cancer Symposium.

"If caught before it spreads, patients can survive breast cancer," said Richard Gaynor, head of product development and medical affairs at Lilly Oncology.

"However, for the nearly 10 per cent of patients who are initially diagnosed at stage IV, and the nearly 30 per cent of patients whose early-stage cancer will re-occur as metastatic disease, there remains an urgent need for effective therapy options."

Abemaciclib is a cyclin-dependent kinase (CDK) 4 and 6 inhibitor, in the same class as Pfizer's Ibrance (palbociclib) which was granted accelerated approval by the US FDA as a first-line therapy for advanced, hormone-positive breast cancer earlier this year.

Ibrance has already racked up sales of $140 million in the US since its launch in February, and has been given peak sales forecasts of $3 to $5 billion by analysts.

As it bids to catch up, Lilly is carrying out two phase III trials of abemaciclib in HR+/HER2-negative breast cancer as well as a phase III trial in lung cancer. It also has a phase II trial ongoing – MONARCH 1 – in HR+ breast patients whose tumours are also negative for human epidermal growth factor receptor 2 (EGFR2).

It has other competition looming too; Novartis also has a CDK 4/6 inhibitor called ribociclib in phase III development, while Cyclacel has a CDK2/9-targeting candidate, CYC065, in early clinical development for various solid and blood cancers.

Meanwhile, Pfizer also has ambitions to expand the use of Ibrance into new indications, and is currently conducting studies in head and neck cancer patients in combination with Merck KGaA/Eli Lilly's Erbitux (cetuximab) as well as pancreatic cancer.

In 2001, the Nobel Prize in Physiology or Medicine was awarded jointly to Leland Hartwell, Tim Hunt and Paul Nurse for the discovery of CDKs and their role in the checkpoint control of cancer cells.