Halozyme Therapeutics has started dosing patients with gastric cancer in a Phase Ib/II clinical trial of its investigational new drug PEGPH20 combined with atezolizumab (Tecentriq).

PEGPH20 is a PEGylated form of the firm’s recombinant human hyaluronidase, while atezolizumab is Genentech’s anti-PDL1 cancer immunotherapy.

Being developed as an enzyme, PEGPH20 could temporarily degrade HA component in the tumour microenvironment that might constrict blood vessels upon accumulation.

The degradation is expected to result in decreased tumour pressure and increased blood flow to enable better access for chemotherapies and immunotherapies.

The open-label, multi-centre, randomised Phase Ib/II trial will investigate the safety, tolerability, pharmacokinetics and preliminary anti-tumour activity of the combination in subjects with previously treated locally advanced unresectable or metastatic gastric or gastroesophageal junction cancer.

To be conducted in the US and additional international markets, the trial includes a retrospective analysis of the HA-high population detected through Ventana HA companion diagnostic assay.

“Our hope is to advance new treatment options for patients with each ongoing study.”

Halozyme Therapeutics president and CEO Dr Helen Torley said: “PEGPH20 is currently under evaluation in six indications with potential across a range of difficult to treat solid tumours.

“Our hope is to advance new treatment options for patients with each ongoing study.”

The Phase Ib/II trial is part of the firm’s clinical collaboration agreement formed last year with Genentech to study the PEGPH20 and atezolizumab combination for up to eight different types of tumour.

Under the collaboration, the combination will be evaluated on Roche‘s Phase Ib/II cancer immunotherapy development platform, Morpheus, designed for the development of rapid and efficient cancer immunotherapy combinations.