Immune checkpoint enhancer biotech AltruBio raises $225m

A healthy run of nine-figure private rounds for biotechs in the US has continued with an impressive $225 million Series B for immunotherapy specialist AltruBio.

The San Francisco-based company is working on drugs that work in the opposite way to immune checkpoint inhibitors that have transformed the treatment of cancer, focusing on candidates that tap the brakes on immune responses that have been revved up in autoimmune and inflammatory diseases.

The new funding follows a $63 million Series A completed in 2021, and comes as AltruBio is testing its lead candidate – ALTB-268 for ulcerative colitis – in a phase 2a trial involving patients with moderately to severely active disease refractory to biologic therapies. The study is due to read out in 2026.

There have been some forks in the road for AltruBio since it completed its first round, which came as the biotech shifted its focus away from cancer and to the development of immune checkpoint enhancer neihulizumab (ALTB-168), which was being tested for ulcerative colitis, as well as steroid-refractory acute graft-versus-host disease (SR-aGVHD), psoriatic arthritis, and psoriasis.

Fast forward to now, and neihulizumab has been sidelined, with AltuBio’s attention switched to ALTB-268, as it offers the same mechanism of action and also increased potency for subcutaneous administration.

Both drugs bind to CD162 (also known as PSGL-1), leading to downregulation of activated T-cells without affecting resting T-cells and early-activated T-cells. In principle, that should allow them to dampen down the overactive immune response without having an impact on normal immune defences. To date, no drugs addressing this target have reached the market.

Chief executive Dr Judy Chou said the financing round “not only affirms the potential of our programme and company, but also our mission of developing durable biologic therapies for patients suffering from autoimmune diseases.”

She added: “With this substantial investment, we are one step closer to bringing our first-in-class, novel immune checkpoint enhancer, ALTB-268, through our ongoing phase 2a exploratory biomarker study and initiate an additional Phase 2b study, while paving the way for potential indication expansion beyond ulcerative colitis.”

The financing was led by BVF Partners LP, with participation from new investors RA Capital Management, Cormorant Asset Management, Soleus Capital, and Delos Capital, as well as existing investors aMoon Fund and Blackstone Multi-Asset Investing. Other new and existing investors also joined in, said AltruBio.