Johnson & Johnson’s Tremfya Becomes First IL-23 Inhibitor Approved for Pediatric Psoriasis and Psoriatic Arthritis; Genmab Secures Breakthrough Bispecific Antibody Petosemtamab in $8B Merus Acquisition

First! Johnson & Johnson Antibody Therapy Receives FDA Approval Again

Johnson & Johnson announced today that the U.S. FDA has approved its anti-IL-23 antibody Tremfya (guselkumab) for the treatment of pediatric patients aged 6 years and older, weighing no less than 40 kilograms, with moderate to severe plaque psoriasis (PsO) or active psoriatic arthritis (PsA). PsO patients must qualify for systemic therapy or phototherapy.According to the press release, this approval makes Tremfya the first IL-23 inhibitor approved for the treatment of the aforementioned pediatric patient population.

The approval of this plaque psoriasis indication is mainly based on the results of the Phase 3 PROTOSTAR study and supportive data from the Phase 3 VOYAGE 1 and 2 adult studies. In the PROTOSTAR study, Tremfya achieved the co-primary endpoints at week 16:Approximately 56% of pediatric patients achieved at least a 90% improvement in the Psoriasis Area and Severity Index (PASI 90), compared to only 16% in the placebo group (p<0.01); meanwhile, 66% of patients in the Tremfya group reached an Investigator's Global Assessment (IGA) score of 0/1 (clear or almost clear skin), compared to only 16% in the placebo group (p<0.001).Notably, nearly 40% of patients in the Tremfya group achieved complete skin symptom clearance (IGA 0) by Week 16, compared to only 4% in the placebo group (p<0.01), further highlighting the efficacy of this therapy in pediatric patients.The approval of the PsA indication this time has obtainedTremfyaSupported by evidence from pharmacokinetic extrapolation analyses in PsO and PsA studies, including the VOYAGE 1 and 2, DISCOVER 1 and 2, and PROTOSTAR trials.

$8 Billion! Genmab Acquires Breakthrough Bispecific Antibody Therapy

Genmab and Merus Announce Agreement: Genmab to Acquire Merus for Approximately $8 BillionMerus's lead therapy is the bispecific antibody petosemtamab, which is in late-stage development. The therapy is currently undergoing two Phase 3 clinical trials for head and neck cancer, covering both first-line and second/third-line treatment settings., with top-line interim data from one or both trials expected in 2026.

Petosemtamab is a humanized full-length IgG1 antibody that targets the epidermal growth factor receptor (EGFR) and leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5).Petosemtamab Granted Breakthrough Therapy Designation by US FDA in February 2025 for Use in Combination with PD-1 Inhibitor Pembrolizumab as First-Line Treatment for Recurrent or Metastatic PD-L1 Positive Head and Neck Squamous Cell Carcinoma (HNSCC) in Adult Patients.

In May this year, the Phase 2 trial data presented at the American Society of Clinical Oncology (ASCO) Annual Meeting showed that, among 43 evaluable adult patients with recurrent or metastatic PD-L1 positive HNSCC, the combination of petosemtamab and pembrolizumab as a first-line therapy demonstrated an investigator-assessed confirmed overall response rate of 63% (27/43, 95% CI: 49-75), including 6 complete responses and 21 partial responses.The overall response rate for patients with tumor PD-L1 expression Combined Positive Score (CPS) of 1-19 was 47% (8/17); the overall response rate for patients with CPS >20 was 73% (19/26).The 12-month overall survival rate reached 79%.。

Treatment of Early-Stage Breast Cancer: Major ADC Achieves Positive Results in Second Phase 3 Trial

Today, AstraZeneca and Daiichi Sankyo announced that their jointly developed重磅 antibody-drug conjugate (ADC) Enhertu (trastuzumab deruxtecan) achieved positive results in the DESTINY-Breast05 Phase 3 clinical trial.Compared with the active control drug, Enhertu statistically significantly and clinically meaningfully improved invasive disease-free survival (IDFS) in HER2-positive early breast cancer patients who had residual invasive disease in the breast or axillary lymph nodes after neoadjuvant therapy and were at high risk of recurrence.Following the positive results from the Phase 3 DESTINY-Breast11 study announced earlier this year, this is the second positive outcome from a Phase 3 trial for Enhertu in the HER2-positive early breast cancer space. The company is advancing related regulatory submissions.

Enhertu is an ADC therapy jointly developed by AstraZeneca and Daiichi Sankyo. It is designed using Daiichi Sankyo's proprietary DXd ADC technology platform and consists of a humanized monoclonal antibody targeting HER2, connected via a cleavable tetrapeptide linker to a topoisomerase 1 inhibitor payload.

References:

[1] ENHERTU® Demonstrated Highly Statistically Significant and Clinically Meaningful Improvement in Invasive Disease-Free Survival Versus T-DM1 in DESTINY-Breast05 Phase 3 Trial in Patients with High-Risk Early Breast Cancer Following Neoadjuvant Therapy. Retrieved September 29, 2025 from https://www.businesswire.com/news/home/20250928521193/en/ENHERTU-Demonstrated-Highly-Statistically-Significant-and-Clinically-Meaningful-Improvement-in-Invasive-Disease-Free-Survival-Versus-T-DM1-in-DESTINY-Breast05-Phase-3-Trial-in-Patients-with-High-Risk-Early-Breast-Cancer-Following-Neoadjuvant-Therapy

[2] Genmab to Acquire Merus, Expanding Late-Stage Pipeline and Accelerating into a Wholly Owned Model. Retrieved September 29, 2025 from https://www.businesswire.com/news/home/20250928964515/en/Genmab-to-Acquire-Merus-Expanding-Late-Stage-Pipeline-and-Accelerating-into-a-Wholly-Owned-Model

[3] U.S. FDA approves TREMFYA® (guselkumab) for the treatment of pediatric plaque psoriasis and active psoriatic arthritis, marking a first and only approval for an IL-23 inhibitor. Retrieved September 29, 2025 from https://www.prnewswire.com/news-releases/us-fda-approves-tremfya-guselkumab-for-the-treatment-of-pediatric-plaque-psoriasis-and-active-psoriatic-arthritis-marking-a-first-and-only-approval-for-an-il-23-inhibitor-302569442.html

[4] Delivering Genmab’s Next Decade of Sustainable Growth. Retrieved September 29, 2025, from https://ir.genmab.com/static-files/5eedd07d-a6c0-4bd7-9c27-f082204450b9

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