Pharming announces positive Phase II topline data for leniolisib in PIDs with immune dysregulation accepted as late-breaking abstract at ESID 2026

Leniolisib was generally well-tolerated, with clinical improvements across multiple measures of immune dysregulation, including reductions in lymphoproliferation

Separately, Pharming expects to report topline results from a Phase II trial of leniolisib in CVID in Q4 2026

Leiden, the Netherlands, September 22, 2026: Pharming (Euronext Amsterdam: PHARM/Nasdaq: PHAR), a global biotechnology company focused on rare immune and genetic diseases, today announced that a late-breaking abstract highlighting positive topline data from its Phase II trial with leniolisib in genetically identifiable primary immunodeficiencies (PIDs) with immune dysregulation linked to PI3Kd signaling has been accepted at the 22 nd Biennial Meeting of the European Society for Immunodeficiencies (ESID), which will take place October 14-17, in the Netherlands.

This trial is a single-arm, open-label, intra-patient dose-escalation Phase II study of leniolisib evaluating safety and tolerability, pharmacokinetic, pharmacodynamic and efficacy measures in 13 subjects with genetically defined PIDs. The abstract will highlight leniolisib’s favorable safety and tolerability profile, as well as clinical improvements across measures of immune dysregulation. Clinical results included improvements in lymphoproliferative disease, with a mean 26.4% spleen volume reduction (SVR) and reductions in the size of index lesions. The safety observations were consistent with the known safety profile of leniolisib, with infections as the most common events observed in study subjects, and no new safety signals identified. Additional data will be presented at ESID 2026.

Of the 13 patients enrolled in the study, nine also had a diagnosis of common variable immunodeficiency (CVID). Pharming expects to report Phase II results for leniolisib in CVID patients with immune dysregulation, with or without an identified genetic cause, in the fourth quarter of 2026.

“These results mark an important step in assessing leniolisib’s potential to address immune dysregulation in PIDs beyond APDS, potentially benefiting a substantially larger patient population,” said Anurag Relan, Chief Medical Officer of Pharming. “Given PI3Kδ’s central role in immune dysregulation mechanisms, these results are encouraging and support ongoing development of leniolisib in PID patients with APDS-like manifestations. We look forward to sharing additional results from this trial at ESID, along with topline results from our separate Phase II trial in CVID, expected in the fourth quarter, which will inform our plans for a potential registrational study in the broader CVID population.”

Abstract details:

Title: Single-arm, open-label, Phase 2 study of leniolisib in patients with inborn errors of immunity linked to dysregulated PI3K pathway signaling: Topline safety and efficacy outcomes Author: Gulbu Uzel, MD

The presentation will be available for viewing at ESID 2026 for the full duration of conference.

About leniolisib Leniolisib is an oral small molecule phosphoinositide 3-kinase delta (PI3Kẟ) inhibitor approved as the first and only targeted treatment of activated phosphoinositide 3-kinase delta (PI3Kδ) syndrome (APDS) in adult and pediatric patients 12 years of age and older in the U.S., U.K., Australia, Israel, the EU, Canada, and South Korea; in children 4 to 11 years of age who weigh at least 27 kg in the U.S., and for patients 4 years of age and older in Japan.

Leniolisib inhibits the production of phosphatidylinositol-3-4-5-trisphosphate, which serves as an important cellular messenger and regulates a multitude of cell functions such as proliferation, differentiation, cytokine production, cell survival, angiogenesis, and metabolism. Results from a randomized, placebo-controlled Phase III clinical trial demonstrated statistically significant improvement in the coprimary endpoints, reflecting a favorable impact on the immune dysregulation and deficiency seen in these patients, and open label extension data has supported the safety and tolerability of long-term leniolisib administration. 1,2

Leniolisib is currently under regulatory review for the treatment of APDS in several other countries. Leniolisib is also being evaluated in two Phase II clinical trials in primary immunodeficiencies (PIDs) with immune dysregulation. The safety and efficacy of leniolisib has not been established for PIDs with immune dysregulation beyond APDS .

About Pharming Pharming Group N.V. (Euronext Amsterdam: PHARM/Nasdaq: PHAR) is a global biotechnology company that develops and commercializes innovative medicines for people living with rare immune and genetic diseases.

We combine specialized scientific, medical, regulatory and commercial expertise to advance a focused portfolio of approved medicines and development programs that address significant unmet medical needs. Guided by insights from patients and the wider rare disease community, we are dedicated to delivering innovative therapies for some of the most challenging rare diseases.

Pharming is headquartered in Leiden, the Netherlands, with operations in the United States and Europe.

For more information, visit www.pharming.com and find us on LinkedIn .

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References

Rao VK, et al. Blood. 2023;141(9):971-983.

Rao VK, et al. J Allergy Clin Immunol 2024;153:265-74.

For further public information, contact: Pharming Michael Levitan, VP Investor Relations & Capital Markets T: +1 (908) 705 1696 E: investor@pharming.com

Saskia Mehring, Head of Corporate Communications T: +31 6 28 32 60 41 E: media.relations@pharming.com

Media Relations Julia Deutsch (Lyra Strategic Advisory on behalf of Pharming) E: [email protected]

Netherlands: Leon Melens (LifeSpring Life Sciences Communication on behalf of Pharming) T: +31 6 53 81 64 27

Pharming announces Phase II topline data for leniolisib in PIDs_EN_22SEP2026