Johnson & Johnson is leaning on a flawed study to advertise its prostate cancer drug as having lower risk of death compared with Bayer's medication, alleged a New York federal lawsuit filed Monday by Bayer, which seeks to immediately halt J&J's advertising campaign and recover damages.

Bayer HealthCare LLC asked a New York District Court to immediately block Johnson & Johnson and its subsidiary Janssen Biotech Inc. from "falsely claiming" that patients with prostate cancer had a 51% reduced chance of dying if they were treated with J&J's Erleada compared with if they were treated with Bayer's Nubeqa.

In its 40-page complaint, Bayer said the "real world head-to-head analysis" that J&J used to make this assertion does not meet U.S. Food and Drug Administration standards for making superiority claims over another medication.

Ultimately, Bayer added, this campaign works to undermine doctor and patient trust in Bayer's Nubeqa and "permanently shift prescribing patterns in ways that cannot be fully quantified or remedied through monetary damages."

"Bayer has no adequate remedy at law for these injuries," the suit said. "No monetary remedy would be adequate to compensate Bayer for the injury that J&J's wrongful acts have caused to Bayer's reputation, goodwill, market share, and sales, and for the injury that Bayer will suffer should those acts not be enjoined."

Beyond a preliminary injunction, Bayer seeks cash, including compensatory and punitive damages for what it called "egregious conduct." It also asked the court to force J&J to issue a press release correcting the record.

A spokesperson for J&J told Law360 the company stands by the integrity of the study and the claim that its drug shows "a 51% reduction in risk of death for patients with metastatic castration-sensitive prostate cancer."

"Litigation does not change data," the statement said. "Our analysis was designed to meet rigorous regulatory guidance on real-world evidence, and this legal action demonstrates Bayer's obvious misunderstanding of methodological frameworks and real-world evidence principles."

According to the complaint, both drugs are used in the "doublet therapy" strategy for treating prostate cancer. The drugs are designed to block testosterone, which is what the cancer uses to grow.

The suit claims that the drugs are "direct competitors in a relatively concentrated and highly competitive market." J&J's Erleada secured FDA approval in September 2019, while Bayer received approval for its drug in June.

Once on the market, Nubeqa proved to be a solid product for Bayer, with sales of $1.81 billion during the first nine months of 2025, the suit said.

"Faced with this new competition, J&J launched a false advertising campaign against NUBEQA in February 2026," the suit added.

This campaign, Bayer said, centered on a press release that made the claim that its drug showed a "51% reduction in risk of death for patients with metastatic castration-sensitive prostate cancer treated with ERLEADA® (apalutamide) versus darolutamide without docetaxel through 24 months."

Bayer claims this study is not useful because the period, August 2022 to June 2025, almost entirely predates Nubeqa's FDA approval for doublet therapy. For much of that time, doctors were using Bayer's drug to treat prostate cancer in an off-label manner, a choice physicians sometimes make when regular treatments are not proving helpful. This means many patients who got Bayer's drug were likely sicker and therefore not comparable to those who were receiving J&J's drug, the suit claims.

Additionally, Bayer claims that at least 60% of patients in J&J's analysis began treatment after June 2023, saying they therefore could not have been followed for a full 24 months by the study's end in June 2025, as the press release claims.

Bayer HealthCare LLC is represented by Lynn K. Neuner, Laura Brett, Nicholas Cunha and Simona G. Strauss of Simpson Thacher & Bartlett LLP.

Counsel information for J&J wasn't immediately available.

The case is Bayer Healthcare LLC v. Johnson & Johnson et al., case number 1:26-cv-01479, in the U.S. District Court for the Southern District of New York.