Recludix Pharma’s REX-8756 for Type 2 Inflammatory Diseases Enters First Human Trials

Recludix Pharma has announced the initiation of clinical dosing in a first-in-human phase 1 study of REX-8756 (SAR448755), an oral, small-molecule inhibitor of signal transducer and activator of transcription 6 (STAT6).¹ This milestone follows clearance of the Investigational New Drug (IND) application by the US Food and Drug Administration in December 2025 and triggered a $20 million milestone payment to Recludix under its strategic collaboration with Sanofi.²

“The initiation of our first clinical study is a pivotal step forward in executing our long-term vision of discovering and developing innovative medicines for patients in need. This milestone reflects the strength of our science and platform, as well as the capabilities of our highly experienced team,” said Nancy Whiting, PharmD, president and chief executive officer of Recludix. “We see tremendous potential for our STAT6 inhibitor, REX-8756, to set a new standard in the treatment of Type 2 inflammatory diseases.”¹

STAT6 is a transcription factor that plays a pivotal role in mediating the downstream effects of interleukin-4 (IL-4) and interleukin-13 (IL-13), cytokines that drive many allergic and Type 2 immune responses in diseases such as atopic dermatitis and chronic spontaneous urticaria. An oral STAT6 inhibitor offers the potential to block this pathway more proximally, providing biologic-like efficacy in a small-molecule format.

In pre-clinical trials, REX-8756 demonstrated rapid, potent, and durable suppression of STAT6 signaling across multiple models of inflammatory disease. Importantly, this effect was achieved without inducing protein degradation, suggesting a differentiated mechanism that preserves STAT6 protein levels while functionally silencing its transcriptional activity. In disease models, this translated into marked suppression of inflammatory pathways driven by IL-4 and IL-13.

The ongoing phase 1 study is a randomized, blinded, placebo-controlled study expected to enroll approximately 100 healthy volunteers. The trial is structured to include both single ascending dose and multiple ascending dose cohorts, allowing investigators to characterize the safety, tolerability, pharmacokinetics, and pharmacodynamics of REX-8756.

This development program is being carried out under a broad collaboration between Recludix and Sanofi. Under the terms of the agreement, Recludix is responsible for advancing STAT6 inhibitors through preclinical development and into phase 2 clinical trials, after which Sanofi will assume global responsibility for further clinical development and commercialization. Sanofi holds worldwide rights to small-molecule STAT6 inhibitors generated through the partnership, while Recludix retains an option to participate in a 50% profit-and-loss share in the US, including co-promotion rights.

With the dosing of the first subjects in the phase 1 study, Recludix has now received a total of $145 million in milestone payments from Sanofi. The agreement also includes the potential for more than $1.2 billion in additional development, regulatory, and commercial milestones, as well as double-digit royalties on future product sales.

“We are excited to advance REX-8756 to the clinic, especially given the robust efficacy and differentiated safety profile it demonstrated in preclinical studies. We would like to acknowledge our partner Sanofi for their valuable contributions and collaboration in accelerating this progress. Both companies share the excitement of reaching this important milestone together and look forward to generating the clinical data that will guide our next phase of development,” said Ajay Nirula, MD, PhD, executive vice president and head of R&D at Recludix.¹

References

1. Recludix Pharma Announces Dosing of First Subjects in a Phase 1 Study of REX-8756, a Potent and Selective Oral STAT6 Inhibitor, and Achieves Associated $20 Million Milestone Payment Under Collaboration with Sanofi. News release. Recludix Pharma. Published January 12, 2026. Accessed January 13, 2026. https://www.globenewswire.com//news-release/2026/01/12/3216802/0/en/recludix-pharma-announces-dosing-of-first-subjects-in-a-phase-1-study-of-rex-8756-a-potent-and-selective-oral-stat6-inhibitor-and-achieves-associated-20-million-milestone-payment-u.html

2. Recludix Pharma announces FDA clearance of Investigational New Drug Application for REX-8756, an oral STAT6 Inhibitor, to enter into the clinic. News release. Recludix Pharma. Published December 16, 2025. Accessed January 13, 2026. https://recludixpharma.com/recludix-pharma-announces-fda-clearance-of-investigational-new-drug-application-for-rex-8756-an-oral-stat6-inhibitor-to-enter-into-the-clinic/