Portage Adds Four Adenosine Candidates to Pipeline in Tarus Buyout


Clinical-stage immuno-oncology company Portage Biotech announced Wednesday that it has inked an acquisition agreement with New York-based Tarus Therapeutics.

The deal will see Portage hand over nearly 2.5 million shares, assume $3 million of Tarus’ outstanding liabilities and commit up to $32 million in milestones, payable in cash or shares. The transaction also adds four best-in-class compounds to Portage’s already-healthy pipeline, each targeting different parts of the adenosine pathway.

Adenosine is a strong immunosuppressive molecule that tumors release into their immediate environment, helping them evade or weaken the immune system. In many cancers, overexpression of the adenosine receptors A2A and A2B are known as poor prognostic factors, contributing to high rates of disease progression or death. Several immunotherapeutic approaches to cancer like Portage’s seek to target and block these receptors.

“We’re excited that … we were able to bring on a really nice set of assets that we think is in a target that’s been somewhat validated by some of our peers but where we have potentially best-in-class assets with significant advantages over the existing products. And we did that in a way that was capital-efficient and increased our clinical candidate pipeline.” Ian Walters, M.D., CEO and director of Portage, said during an investor conference call Thursday morning. 

The assets acquired in the buyout include A2B blockers PORT-7 (formerly TT-4) and PORT-9 (formerly TT-3). The former has been granted an Investigational New Drug clearance for solid tumor treatment, and Portage plans to begin its clinical development next year; the latter, PORT-9, is undergoing preclinical assessments for gastrointestinal cancers.

Portage will also receive the A2A inhibitor PORT-6 (formerly TT-10) for solid tumors. The candidate has likewise been granted IND approval and will enter Phase I/II trials later this year. The final asset is the dual inhibitor PORT-8 (formerly TT-53), which targets both A2A and A2B receptors, and also treats solid tumors.

These four candidates could synergize well with other drugs in Portage's development pipeline. PORT-6 and PORT-7, in particular, the two most mature Tarus assets, could give Portage a competitive edge over other blockers in development. For instance, PORT-6 is more target-selective than other A2A blockers, reducing the likelihood of treatment toxicities, and can keep the receptors blocked for much longer, leading to more sustained drug efficacy.

Walters revealed during the call that Portage has set its sights on a study named TOAST-1 to assess PORT-6 and PORT-7. The study will run two parallel arms, both of which will start with a dose-escalation monotherapy phase of the candidates separately, and could eventually transition into testing combinations of PORT-6/7 with other cancer immunotherapies.

Depending on the outcomes, TOAST-1 would take the most promising combos of PORT-6/7 into a randomized trial, pitting the drug candidates against the standard of care.

To help fund its adenosine pipeline and other programs, Portage has entered into a committed share purchase agreement with Chicago-based institutional investor Lincoln Park Capital Fund LLC (LPC). In exchange for some 95,000 ordinary shares upfront, the deal enables Portage to sell up to $30 million worth of ordinary shares to LPC over the 36-month duration of the purchase agreement. This agreement potentially secures Portage’s cash runway until 2024.

“This additional capital gives us the flexibility to fully fund multiple new products from the Tarus acquisition, as well as extend our runway for our existing products into 2024,” Walters said. “This enabled us to have the confidence to take on these additional products and push them into the clinics.”

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