A cautionary tale for clinical trial collaborators

When biotechs sign clinical trial collaborations with big pharma these are frequently seen as important endorsements from possible future partners. But things don't always play out this way, as Asher Bio found out recently when its collaboration with AstraZeneca was terminated.

This tie-up concerned Asher's CD8-guided IL-2 project etakafusp alfa, which was to have been taken forward as part of a combo with Astra's rilvegostomig. It's just emerged that Astra ended this arrangement in May, and two months later began a study testing rilvegostomig combined with its own CD8-guided IL-2, AZD6750.

While there’s no indication of inappropriate behaviour, the case highlights the problems small biotechs face when entering into clinical trial collaborations, which they might contribute to meaningfully, but from which they risk getting little in return.

CD8 guiding

Astra has pushed forward with CD8-guided anticancer therapies, most prominently by applying its Titan and TED4 approaches to developing T-cell engagers. AZD6750 is a molecule that uses CD8 guiding to anchor the cytokine IL-2 to CD8+ T cells, and which started a study testing it with or without rilvegostomig in July. 

Meanwhile, etakafusp alfa is Asher's lead project, and entered human testing in 2023. The private US biotech was founded in 2019, and has worked specifically on targeted delivery of cytokines, so striking a clinical trial collaboration with Astra covering this molecule, as announced in January, was a big deal.

However, Astra has told ApexOnco that it decided to discontinue cohorts testing etakafusp alfa, and terminate the clinical trial collaboration with Asher, citing “portfolio prioritisation”. The trial in question, Altair, is to continue testing other rilvegostomig combinations.

The deal’s ending hadn't previously been disclosed, and clinicaltrials.gov makes it seem as though Altair still plans to test rilvegostomig plus etakafusp alfa. Altair's scheduled start date has been delayed, from 23 May to 7 July to 13 October, but as of Friday the study was still listed as “not yet recruiting”.

The lesson for other small biotechs concerns the risk of striking clinical trial agreements. Unlike specific licensing deals such tie-ups involve minimal financial elements; typically one party supplies its project for the other to use in a clinical trial, but there’s no transfer of ownership.

Try before you buy?

Of course, if the big partner likes what it sees in such an arrangement things can proceed to a formal licensing deal. On the other hand, if it has something similar in its own pipeline, a small partner's own asset can provide something of a free shot that merely emboldens the big pharma to go with its own approach.

In this case Astra has decided to go forward not with etakafusp alfa but with a project of its own, AZD6750. As a CD8-guided IL-2, AZD6750 uses the same approach as etakafusp alfa. A phase 1/2 study combining AZD6750 with rilvegostomig – the same combo that was to gave been investigated with etakafusp alfa – started in July.

There's no suggestion that anything untoward happened between Astra and Asher, which are understood to have worked together informally for four years. Indeed, Asher has stressed to ApexOnco that Astra's venture financing arm remains a key private investor.

Since Astra has never published the structure of AZD6750 it's not even clear how similar this molecule is to etakafusp alfa. Asher appears to have patented the latter in 2020, while Astra's patent covering AZD6750 was published in August 2025, and cites both Asher's IP and a 2019 Roche patent claiming fusions of IL-2 with CD8 binders.

Meanwhile, Asher's work with etakafusp alfa continues, and the group closed a $55m series C financing round in April. It has two other clinical trial collaborations in place, with Amgen covering an Imdelltra combo, and with Merck & Co covering a Keytruda combo in Keynote-E29.

Two AstraZeneca trials of CD8-guided IL-2 projects

Source: clinicaltrials.gov & company communication.