US-based biotechnology company Halozyme Therapeutics has announced dosing of the first patient by Eisai in the collaborative Phase Ib/II clinical trial of eribulin mesylate and PEGPH20 to treat women with advanced or metastatic, high-hyaluronan (HA) HER2-negative breast cancer.

Eisai's eribulin mesylate (Halaven) is a synthetic analog of halichondrin B, a natural product separated from the marine sponge Halichondria okadai, a microtubule dynamics inhibitor.

PEGPH20 is an investigational PEGylated form of Halozyme's patented, recombinant human hyaluronidase administered intravenously.

The trial has been designed to assess the efficacy of the combination of PEGPH20 and eribulin in improving the overall response rate (ORR) in women with metastatic breast cancer displaying high levels of HA.

"Eribulin is believed to work on a tubulin-based mechanism, resulting in the death of cancerous cells as it blocks its regeneration."

It will enrol metastatic HER2-negative patients with HA-high breast cancer who were previously untreated, as well as patients who had received one prior line of treatment.

The trial will compare the effects of the combination of drug with women who already had predefined reduction in tumours after being administered with eribulin alone as a therapy.

Halozyme president and CEO Dr Helen Torley said: "Initiation of this study is not only a major milestone in our collaboration with Eisai, it underscores our combined focus on advancing the treatment of metastatic breast cancer, one of the most common cancers in women worldwide."

Eribulin is believed to work on a tubulin-based mechanism, resulting in the death of cancerous cells as it blocks its regeneration.

PEGPH20 inhibits HA, a glycosaminoglycan or a chain of natural sugar that gathers around cancer cells to shield it from therapies.