Targovax ASA's (OSE: TRVX) TG02 has passed the initial planned safety review in the Phase Ib clinical mechanism-of-action trial evaluating TG02 as a monotherapy and in combination with the checkpoint inhibitor Keytruda (pemprolizumab), in patients with RAS-mutated colorectal cancer, the company disclosed on Monday.

The Phase Ib exploratory, multi-site, open-label, non-randomised trial will enrol around 20 patients with locally recurrent rectal cancer, where specific poor-prognosis mutations in the RAS gene have been confirmed. The study will involve two cohorts of up to 10 patients, with the first receiving TG02 and granulocyte macrophage colony stimulating factor (GM-CSF) as a monotherapy, and the second receiving this in addition to the PD-1 checkpoint inhibitor, Keytruda.

The study's primary objective is to assess the safety of TG02 and to evaluate the impact of the vaccination on systemic and local innate and adaptive immune response of treated patients. The trial is currently enrolling patients at sites in Australia and New Zealand.

The safety review involved the initial three patients that were enrolled on the first cohort, receiving TG02 as a monotherapy. No issues were reported and it was recommended that the trial continue. This marks the first time the vaccine was administered to patients.

Early exploratory clinical results suggest that TG02 induces immune response in patients, with high activation status of tumour-infiltrating T-cells, when compared to historical controls. The company will now work with investigators to determine the appropriate timing for switching into the Keytruda combination part of the trial, and when to begin recruiting patients for that cohort.