• Additional data continues to support highly differentiated profile for FB102 in celiac disease

DALLAS / Sep 15, 2025 / Business Wire / Forte Biosciences, Inc. (www.fortebiorx.com) (NASDAQ: FBRX), a clinical-stage biopharmaceutical company focused on autoimmune and autoimmune-related diseases, announced additional details from the oral presentation “FB102 prevents histological damage and mitigates gluten challenge-induced symptoms in a celiac disease phase 1b study - Jason Tye-Din, Walter and Eliza Hall Institute; Royal Melbourne Hospital” at the Tampere Celiac Disease Symposium 2025 (Tampere, Finland) on Friday September 12, 2025, further supporting the significant differentiation of FB102 in celiac disease.

Highlights of the oral presentation include:

• FB102 demonstrated a decline in the TCR γδ density from baseline of 1.5 compared to an increase of 3.9 for placebo (p=0.0007)
  • TCR γδ cells produce pro-inflammatory cytokines including IFN-γ and TNF-α and upregulate activating receptors on epithelial cells triggering cytotoxic responses that directly kill the epithelial cells.
• Ki67-positive intraepithelial cell density increased from baseline by 8.6 on placebo compared to 2.5 on FB102 (p=0.0006)
  • Ki67 is a marker of T cell proliferation (inflammation) on gluten exposure in celiac disease
• NK cells declined by 95% following FB102 dosing
  • IL-15 upregulates activating receptors and confers resistance to activation-induced cell death and enhances T cell epithelial cytotoxicity in celiac disease. NK cell reduction is a marker of IL-15 pathway inhibition.
• No statistically significant difference in Tregs between FB102 and placebo at any timepoint.
  • Regulatory T cells (Tregs) help to modulate the immune response in autoimmune diseases like celiac disease.

“We want to thank all of the clinical trial sites for participating in the FB102-101C study,” said Forte Biosciences CEO Paul Wagner, PhD. “The results presented by Prof. Jason Tye-Din, Head of Celiac Research at the Walter and Eliza Hall Institute at the Royal Melbourne Hospital and principal investigator in the FB102 phase 1b trial, at the Tampere Celiac Disease Symposium further reinforce the differentiation of FB102 in celiac disease. The phase 2 FB102 celiac disease trial is underway with topline data coming in 2026. The FB102 impact on the additional IEL subtypes in the phase 1b trial is extremely encouraging with respect to the additional therapeutic indications Forte is pursuing, including vitiligo and alopecia areata with data from both of these trials expected next year.

Additional details can be found in the presentations posted to the investor relations section of Forte’s website at www.fortebiorx.com.

About Forte

Forte Biosciences, Inc. is a clinical-stage biopharmaceutical company that is advancing FB102, which is a proprietary anti-CD122 monoclonal antibody therapeutic candidate with potentially broad autoimmune and autoimmune-related indications.

Forward-Looking Statements

Forte cautions you that statements included in this press release that are not a description of historical facts are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplates,” “believes,” “estimates,” “predicts,” “potential” or “continue” or the negatives of these terms or other similar expressions. These statements are based on the Company’s current beliefs and expectations. Forward-looking statements include statements regarding the Company’s beliefs, goals, intentions and expectations regarding its product candidate, FB102 and the therapeutic and commercial market potential of FB102, expectations for patient enrollment and timing of clinical data readouts. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of various risks and uncertainties, which include, without limitation: risks related to Forte’s ability to obtain sufficient additional capital to continue to advance Forte’s product candidate, FB102; uncertainties associated with the clinical development and regulatory approval of Forte’s product candidate, FB102, including potential delays in the commencement, enrollment and completion of clinical trials, including the timing of the completion of the Company’s patient-based trials; the risk that results from preclinical and any interim result of our ongoing clinical trials may not be predictive of future results from clinical trials; risks associated with the failure to realize any value from FB102 in light of inherent risks, expense and difficulties involved in successfully bringing product candidates to market; and additional risks, uncertainties, and other information affecting Forte’s business and operating results is contained in Forte’s Quarterly Report on Forms 10-Q filed on August 14, 2025, and in its other filings with the Securities and Exchange Commission. All forward-looking statements in this press release are current only as of the date hereof and, except as required by applicable law, Forte undertakes no obligation to revise or update any forward-looking statement, or to make any other forward-looking statements, whether as a result of new information, future events or otherwise. All forward-looking statements are qualified in their entirety by this cautionary statement. This caution is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.