Anthos goes pivotal as Novartis and Pfizer look on

In about 18 months' time Novartis will find out whether it made a mistake to give up on the blood-thinning project abelacimab. The MAb, spun out into the Blackstone-backed Anthos Therapeutics in 2019, yesterday became the first factor XI inhibitor to begin phase 3 patient enrolment. Two pivotal studies, Aster and Magnolia, are now under way, both with primary completion dates of September 2023. The mechanism (abelacimab also hits factor XIa) is an unusual area of research, featuring a small handful of big players, with Bayer and Bristol Myers Squibb working on several distinct assets. Both have franchises to defend: the former’s Xarelto loses US patent protection in 2024, while the latter’s Eliquis will likely go two years later. Unusually, Bristol’s Eliquis partner Pfizer is not active in factor XI, and was asked about this on its first-quarter call. It said: "We really want to see a similar step-up in breakthrough potential as we saw with Eliquis. And we haven't yet been convinced about that step-up, but we are carefully monitoring." The Aster study compares abelacimab head to head against Eliquis, so the answer – for Novartis and Pfizer alike – will come soon enough.

Selected inhibitors of factor XI or XIa
Project Company Mechanism Study design/status
Phase 3
Abelacimab (MAA868) Anthos (ex Novartis) Anti-factor XI & XIa MAb Aster vs Eliquis
Magnolia vs LMW heparin
Phase 2
Osocimab (BAY1831865) Bayer Anti-factor XIa MAb Convert, in dialysis, ended Dec 2021
Fesomersen (IONIS-FXI-LRx/ ISIS 416858/ BAY2306001) Bayer/ Ionis Factor XI ligand conjugated antisense Emerald, in dialysis, ended Dec 2019
Asundexian (BAY 2433334) Bayer Oral factor XIa inhibitor Pacific-AMI ended Feb 2022
Pacific-Stroke ended Feb 2022
Milvexian (JNJ-70033093/ BMS-986177) Bristol Myers Squibb/J&J Oral factor XIa inhibitor Axiomatic-SSP ended Apr 2022
AB023 Aronora Anti-factor XI MAb NCT03612856, in dialysis, ended 2019
Phase 1
ONO-7684 Ono Pharmaceutical Oral factor XIa inhibitor NCT03919890 ended 2019
BMS-986209 Bristol Myers Squibb Oral factor XIa inhibitor NCT04154800 ended Aug 2021
BMS-262084 Oral Bristol Myers Squibb Non-peptide factor XIa inhibitor Unclear
Source: Evaluate Pharma &

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