Amgen stops trial of Teneobio cancer candidate, taking $650M BiTE out of earnings

Amgen’s Teneobio misadventure has taken a $650 million BiTE out of its earnings. The Big Biotech took the hit after stopping a phase 1 trial of the PSMA bispecific it picked up in the $900 million acquisition of Teneobio two years ago.

Buying Teneobio gave Amgen control of AMG 340, a PSMAxCD3 bispecific designed to turn T cells against metastatic castrate-resistant prostate cancer (mCRPC). Amgen already had a PSMA bispecific, acapatamab, when it bought Teneobio. The decision to double up reflected a belief that the drug candidates used “a different approach.” A little more than two years later, both approaches have been found wanting.

Amgen stopped developing acapatamab in the summer of 2022. AMG 340 hung on longer, but the ax was brought down Tuesday. The company disclosed the discontinuation of a phase 1 dose-escalation study of the asset as part of its financial update for the third quarter.

The statement lacks details of the thinking behind the action but does contain information about how it will affect Amgen’s finances. Amgen took a $650 million net impairment charge in relation to the axing of AMG 340, dragging down its earnings per share.

The discontinuation of AMG 340 is the latest in a series of rethinks regarding bispecific T-cell engagers, or BiTEs for short. Amgen dropped candidates aimed at BCMA and PSMA last summer. Amid the changes, the biotech has remained committed to tarlatamab, a DLL3 therapy that recently impressed in a phase 2 trial. Amgen is testing tarlatamab in a form of prostate cancer and has another mCRPC project on the go.

Xaluritamig, a bispecific that binds to STEAP1, is in phase 1b development in mCRPC. Amgen plans to start two more phase 1 trials of the candidate in patients with early prostate cancer. Paul Burton, M.D., Ph.D., chief medical officer at Amgen, recently told Fierce Biotech how xaluritamig illustrates one of two approaches it can take to validate oncology candidates. 

“I think there are two options. One is we can go after cancer by cancer. We're doing that. We're looking at … xaluritamig in prostate. Where we see receptors that are expressed in a variety of different cancer cells, then I think we would also go after a strategy of a basket trial design,” Burton said.

Amgen disclosed the discontinuation of AMG 340 alongside news that it is stopping a phase 1b study of bemarituzumab in squamous non-small cell lung cancer with FGFR2b overexpression. The clinical trial was evaluating the anti-FGFR2b antibody as a monotherapy and in combination with standard of care therapy. Amgen is continuing to study the candidate in a clutch of other phase 1 to phase 3 trials.