# Johnson & Johnson: in Phase 1, pasritamig with JNJ-9401 cut PSA by 50% or more in 11 of 15 patients

- Published: 2026-11-10 17:29 UTC
- Section: Life & Health › Medicine
- Tags: Johnson & Johnson, pasritamig, JNJ-9401, bispecific antibodies, KLK2, PSMA, PSA decline, KLK2-comPAS, Phase 3
- URL: https://realtech.media/news/rt-2bbfa1c8f62b3700942c2365_johnson_johnson_in/

**Early data on a bispecific antibody combination in metastatic castration-resistant prostate cancer come from a small group; the combination now moves into Phase 3.**

![Johnson & Johnson: in Phase 1, pasritamig with JNJ-9401 cut PSA by 50% or more in 11 of 15 patients](https://realtech.media/media/2026/11/4368b98cbcfd2985.webp)
*ad-hoc-news.de*

Johnson & Johnson presented early data on Monday, 9 November 2026, on a combination of two bispecific antibodies, pasritamig and JNJ-9401, in metastatic castration-resistant prostate cancer, according to ad-hoc-news.de. The results come from a Phase 1 study, and the combination is now moving into Phase 3 [1].

## Phase 1 results

Pasritamig and JNJ-9401 target the proteins KLK2 and PSMA and are intended to activate T cells against tumor cells with complementary signals [1]. At the recommended dose, 11 of 15 patients, or 73 percent, had a decline in prostate-specific antigen (PSA) of at least 50 percent. Seven patients, or 47 percent, reached a decline of at least 90 percent, and in four patients PSA was no longer detectable [1]. All seven patients with the deepest decline remained on treatment without disease progression for more than six months [1].

The data come from a small, early group of patients and are therefore not evidence of clinical benefit in a broad population. According to Johnson & Johnson, 144 patients had been enrolled in the ongoing study as of 15 June 2026. The group receiving the recommended combination had been treated with a median of four systemic therapy lines before enrolment [1].

## Safety and next steps

At the recommended dose, the company's release of 9 November reports no treatment-related adverse events of grade 3 or higher, no dose-limiting toxicities, and no treatment-related discontinuations or deaths [1]. Cytokine release syndrome occurred in three patients, in all cases grade 1 with transient fever. No cases of immune effector cell-associated neurotoxicity were reported [1].

The combination will now be studied in the Phase 3 trial KLK2-comPAS. It is intended to determine whether adding JNJ-9401 to pasritamig improves treatment outcomes in metastatic castration-resistant prostate cancer [1]. A further Phase 3 study is testing pasritamig together with docetaxel in the first-line setting. The company is also investigating pasritamig as a single agent and in other combinations [1].

## Sources

1. [ad-hoc-news.de](https://www.ad-hoc-news.de/boerse/news/corporate-news/johnson-johnson-aktie-prostatakrebs-immuntherapie-geht-in-phase-3/70486073)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-2bbfa1c8f62b3700942c2365_johnson_johnson_in/