Medivir AB announced that a safe dose has been established for treatment with the drug candidate fostroxacitabine bralpamide (fostrox) in combination with Keytruda®? in the initial dose escalation part (phase 1b) of the company's 1b/2a study in hepatocellular carcinoma (HCC). In the ongoing expansion part of the study (phase 2a) Medivir is focusing on the fostrox and Lenvima combination and intends to explore the possibility of fostrox in a triple combination together with immunotherapy in earlier lines.

The absolute majority of first-line HCC patients are currently treated with Tecentriq®? (anti-PD-L1) plus Avastin®?. Lenvima®?

is a targeted therapy and there is a clear rationale for using a different mechanism of action in second line- than in first line treatment, to overcome the development of resistance. This makes fostrox + Lenvima®? the most relevant combination to explore further in the second line setting.

With immunotherapy as the standard treatment in first line, the chance, at progression, of responding to further immunotherapy in the following lines is limited, which is why fostrox plus Keytruda®? will not be studied further as a second-line therapy at the moment. With a safe dose established for the fostrox + Keytruda®?

arm, the intention is instead to explore the possibility of fost approx as a triple combination partner in earlier lines of immunotherapy combinations. In the two dose arms of the study, fostrox has been combined with Keytruda®?, an anti-PD-1 checkpoint inhibitor, or Lenvima®?, a tyrosine kinase inhibitor, in patients with HCC for whom first-line treatment has been effective or not tolerated. The aim of the study is to evaluate safety, tolerability and also to get an indication of the effect of fostrox in combination with two already existing drugs.

Medivir announced in February that the dose arm with fostrox + Lenvima™? showed a safe dose and proceeded to the expansion phase (phase 2a), where the first 11 patients have been dosed in a short time. The study is being conducted at 15 clinics in the UK, Spain and South Korea.