Astellas’ $1.3B antibody strikes first in hot cancer field, extending survival in phase 3

Astellas’ $1.3B antibody strikes first in hot cancer field, extending survival in phase 3

Astellas Pharma’s $1.3 billion oncology bet has delivered a phase 3 win. The clinical trial linked the anti-CLDN18.2 antibody zolbetuximab to improved progression-free survival (PFS), moving Astellas a step closer to filing for approval.

Ganymed Pharmaceuticals took zolbetuximab into the clinic and turned heads with gastric cancer data in the summer of 2016, leading Astellas to pay an initial 422 million euros ($437 million) for the biotech later that year. Astellas started a pair of phase 3 clinical trials in 2018 to evaluate the effect of giving the antibody, plus one of two chemotherapy regimens, to patients with gastric and gastroesophageal junction (GEJ) cancer.

The Tokyo-based drugmaker posted top-line data from one of the trials, SPOTLIGHT, on Thursday. In the study, 566 patients with CLDN18.2-positive, HER2-negative, locally advanced unresectable or metastatic gastric or GEJ cancer received the mFOLFOX6 chemotherapy regimen plus zolbetuximab or placebo.

PFS was significantly longer in recipients of zolbetuximab, meaning the study hit its primary endpoint. The therapy scored on a key secondary endpoint, overall survival (OS), too. Astellas is yet to share numbers or p-values for the endpoints, with the company holding those details back for a future scientific congress.

In the trial that preceded Astellas’ takeover, zolbetuximab extended PFS from 4.8 months to 7.9 months and OS from 8.4 months to 13.2 months. Adding phase 3 data to that earlier success has made Astellas more bullish about the prospects of zolbetuximab, as Ahsan Arozullah, M.D., the drug developer’s senior vice president and head of development therapeutic areas, explained in a statement.

“We’re delighted and excited about the positive topline results from the SPOTLIGHT trial of zolbetuximab in combination with mFOLFOX6, and we have increased confidence in advancing development of zolbetuximab for the first-line treatment of patients with locally advanced or metastatic gastric cancer,” said Arozullah.

Attention now turns to a second phase 3 trial, GLOW, that reached primary completion late last month, around six weeks after SPOTLIGHT. Astellas expects the two phase 3 trials to form the basis of filings for approval in the U.S. and other markets.

If GLOW hits its primary goal, Astellas will cement its status as the front-runner in the CLDN18.2 space, giving it a clear run at a target that was expressed by 38% of the patients screened in SPOTLIGHT. But the CLDN18.2 pipeline suggests competitors with different spins on how to hit the target are coming, with companies including BioNTech and Legend Biotech trialing mRNA, CAR-Ts and other modalities.

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