Trillium gets a buyout while it's down

In hindsight, the clues were there: Pfizer’s $25m equity investment in Trillium Therapeutics last year left the big pharma as the only real suitor for the CD47 specialist. And, with Pfizer rolling in Covid-19 vaccine cash and with a need for deals, it made sense to pull the trigger now.

Another reason behind the timing of today’s takeover could be Trillium’s valuation, which is not what it was in late 2020. Even with a 200% premium over Trillium’s closing share price on Friday, at $2.26bn Pfizer is getting the group for less than it was worth last November – and notably it is paying a lot less than the $4.9bn Gilead shelled out for Trillium's competitor Forty Seven last year.  

With several anti-CD47 targets now in the hands of big players, investors are no doubt asking themselves who might be next on the auction block. A look at the table below shows plenty of contenders out there.

Best in class?

Trillium has two shots at CD47 with TTI-621 and TTI-622. Both are anti-SIRPα-Fc fusion proteins, the former an IgG1 and the latter IgG4. Trillium argues that these are the only molecules targeting the SIRPα-CD47 axis that have so far shown clinically meaningful monotherapy responses.

Today, Pfizer and Trillium disclosed a 30% overall response rate among 30 patients in a phase 1 trial of TTI-622, including two complete responses, at a cut-off date of July 26.

However, the recent pivot to combination trials had dented investor confidence about the projects’ monotherapy promise, Evercore ISI’s Josh Schimmer noted. These worries have obviously not put off Pfizer, however, which acknowledged during a call today that Trillium’s projects might not be first in class, but that they have the potential to be best in class.

Executives highlighted data pointing to lower anaemia risk and possibly the potential for the Trillium assets to be dosed lower; both projects also promote a pro-phagocytic signal – or the “eat me” signal – by engaging the activating receptor FcγR on macrophages. Pfizer is targeting regulatory approvals from 2025, they added.

First in class

Gilead’s magrolimab, gained through the Forty Seven purchase, is some way ahead. In myelodysplastic syndrome the group hopes to file for accelerated approval on a phase 1b combo trial with azacitidine, results from which are due later this year.

In front-line acute myeloid leukaemia, meanwhile, Gilead recently started a phase 3 trial of magrolimab plus azacitidine, called Enhance-2.

Another late-stage contender is ALX Oncology’s evorpacept, whose shares climbed 20% today, perhaps on hopes that it could also be a takeout target.

The group will soon start a phase 2/3 trial of the asset in combo with Herceptin in Her2-positive gastric or gastroesophageal junction cancer, Aspen-06. Data in the same setting, from the phase 1 Aspen-01 trial, are set to be presented at next month’s Esmo meeting, which could give clues on this project’s future here.

ALX is also testing evorpacept in combination with Keytruda in head and neck cancer.

Pfizer itself has another CD47-targeting asset in development: a bispecific antibody that also hits PD-L1. However, this is very early in development, with a phase 1 study yet to start recruiting. Whether Pfizer will have to divest this asset to satisfy antitrust regulators is an open question.

Whether other big names now also decide to buy into CD47 or not, Pfizer’s purchase of Trillium is validation of a strategy that looked dead and buried after Celgene discontinued CC-90002 and Surface Oncology quietly shelved SRF231 (Trillium punishes its investors, February 22, 2019). What a difference two years can make in biopharma.