Pfizer shuffles its deck post-Seagen
The group’s B7-H4-targeting bispecific is out, in favour of Seagen’s ADC.
The group’s B7-H4-targeting bispecific is out, in favour of Seagen’s ADC.
Anyone wondering what Pfizer might look like in the wake of its Seagen acquisition got some early clues yesterday, with the big pharma jettisoning an internal B7-H4-targeting bispecific in favour of a Seagen antibody-drug conjugate.
The move is consistent with Pfizer’s $43bn swoop for Seagen and its clear belief in ADCs. Perhaps more surprising is the discontinuation another internal project with a novel target, GUCY2C; it also came to light that several Seagen assets were scrapped ahead of the deal closing in December.
B7-H4
During its fourth-quarter results yesterday Pfizer said it had discontinued PF-07260437, a B7-H4-targeting T-cell engager. The focus here will now be the Seagen-originated ADC SGN-B7H4V – setting up a battle with GSK, which licensed a B7-H4-directed ADC from Hansoh Pharma last year.
AstraZeneca and Mersana are also developing B7-H4 ADCs; there are also several companies testing bispecifics against this target, including Genmab, ABL Bio and Harbour BioMed. If Pfizer is right and ADCs are the way to go, the latter group should be worried.
GUCY2C
Pfizer’s now-abandoned GUCY2C-targeting project was another T-cell engager, PF-07062119. A look at other GUCY2C assets shows a pipeline dominated by Car-T, so perhaps Pfizer decided that it wouldn’t be able to compete on efficacy.
Parasol Biotech’s unnamed contender produced impressive data at ASCO last year, albeit in a Chinese study in only 10 patients; however, results with Beijing Immunochina’s IM96, presented at ESMO, were less emphatic.
Since the last time ApexOnco looked at this space, Legend Biotech has entered the clinic with its “armoured Car-T” LCAR-G08T. All of the groups listed below have a long way to go to prove the merits of this target.
Anti-GUCY2C clinical-stage pipeline
| Project | Description | Company | Trial details |
|---|---|---|---|
| Ad5.F35-hGCC-PADRE | Immunotherapy | Liminatus Pharma | Ph2 in GI cancers* |
| Unnamed | Car-T | Shanghai Stance Biotechnology | China ph2 in colorectal cancer |
| Unnamed | Car-T | Parasol Biotech | China ph1 in colon cancer; data at ASCO 2023: ORR 60% in 10 pts |
| IM96 CAR-T | Car-T | Beijing Immunochina | Early China ph1; data at ESMO 2023: ORR 11% in 9 pts |
| GCC19CART | Car-T | Innovative Cellular Therapeutics | Various ph1s in colorectal cancer, incl. US Carapia-1 |
| LCAR-G08T | “Armoured” Car-T | Legend Biotech | China ph1 in GI cancers |
| XKDCT080 | Car-T | First Condor Biotechnology | China trial in solid tumours* |
Note: *investigator sponsored. Source: OncologyPipeline.
While Pfizer is apparently prioritising ADCs, it appears that there is still room for pruning. Three Seagen assets are no longer listed on Pfizer’s pipeline: SGN-TGT, SGN-ALPV and SGN-STNV.
When asked what had become of these projects, a Pfizer spokesperson told ApexOnco that Seagen had in fact stopped development last year before the deal closed, because of pipeline prioritisation, as disclosed in a November 2023 SEC filing. Perhaps these decisions were taken with an eye of the impending takeover.
Whatever the reason, Pfizer is out of TIGIT just as Gilead is doubling down.
SGN-ALPV, meanwhile, targets alkaline phosphatase placental (ALPP) and ALPP-like 2, proteins expressed on ovarian, endometrial, gastric and testicular cancers. According to OncologyPipeline the only ALPP-targeting project in active clinical trials is ArsenalBio’s AB-1015.
And SGN-STNV targets the Sialyl-Thomsen-nouveau (Stn) antigen, found on various solid tumours including ovarian, non-small cell lung, gastric and endometrial cancers. There are no other active clinical-stage projects against this target, an analysis of OncologyPipeline shows.
Perhaps more details will soon become apparent on Pfizer’s post-Seagen strategy. But there have already been a few early casualties.
This story has been updated to clarify the status of the discontinued Seagen assets.
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