GondolaBio Announces Positive Phase 2a Results Demonstrating 79% Plasma Protoporphyrin IX Reduction and Disease-Modifying Potential of PORT-77 for Erythropoietic Protoporphyria

Trial met its primary endpoint of plasma PPIX reduction, reaching a mean decrease of 79% in the high dose cohort, and 63% in the low dose cohort

Rapid reductions of plasma PPIX levels occurred within hours of treatment, and observed dose-dependent reductions were greater than any intervention for EPP or XLP reported to date

PORT-77 was well tolerated with no serious adverse events or treatment discontinuations, and a lower rate of TEAEs in the PORT-77 period than the placebo period

Based on these results, the PATHWAY Phase 2b/3 trial of PORT-77 in EPP and XLP is targeting initiation in Q3 2026

Results were presented at the EHA 2026 Congress, and will be featured in clinician and patient webinars this week in partnership with leading physician and advocacy networks, APEX, IPNET and GPAC

PALO ALTO, Calif.--(BUSINESS WIRE)--GondolaBio, a clinical-stage biopharmaceutical company developing novel medicines for patients living with genetic diseases, on behalf of its affiliate Portal Therapeutics, today announced positive data from its Phase 2a GATEWAY trial of PORT-77 in patients with erythropoietic protoporphyria (EPP). PORT-77 is a novel investigational oral, small molecule ABCG2 inhibitor designed to treat EPP and X-linked protoporphyria (XLP), two rare genetic disorders characterized by severe, lifelong photosensitivity and liver complications.

"These data represent an important milestone, highlighting PORT-77’s potential to be a disease modifying therapy by significantly reducing PPIX in plasma, the most physiologically relevant blood component for these conditions, which may address the significant unmet need in people living with EPP and XLP," said Pete Schmidt, M.D., M.Sc., Chief Medical Officer of Portal Therapeutics. "Notably, these results demonstrate PORT-77’s potential for leading efficacy, safety, and speed to onset, with rapid and profound reductions in plasma PPIX within hours of dosing. We are encouraged by the magnitude and speed of these reductions, which may translate to patients tolerating more time in the sun and improved quality of life."

The Phase 2a GATEWAY study was a blinded, randomized, placebo-controlled crossover trial evaluating the safety, tolerability, pharmacokinetics (PK), and pharmacodynamic (PD) effects on plasma PPIX of PORT-77 in adults with EPP. Nineteen enrolled participants received placebo followed by 180 mg of PORT-77 oral suspension once daily (QD) or 300 mg twice daily (BID) for four days.

These data were presented at the European Hematology Association (EHA) 2026 Congress in Stockholm, Sweden this month. Key results include:

• PORT-77 was well tolerated, with no serious adverse events, treatment discontinuations, or tolerability signals observed.
• PORT-77 resulted in rapid, dose-dependent reductions in plasma PPIX with a mean decrease of 79% for participants receiving 300 mg BID and 63% for those receiving 180 mg QD.
• Reductions in plasma PPIX were observed within hours of treatment with PORT-77 in both dose groups with no rebound effect after dosing cessation.
• Observed reduction rates were consistent across a broad range of baseline PPIX levels (8–121 µg/dL).

Based on these results and general alignment at the End-of-Phase 2 meeting with the U.S. Food and Drug Administration (FDA) this month, GondolaBio plans to initiate the global Phase 2b/3 PATHWAY trial evaluating the safety and efficacy of PORT-77 in patients with EPP and XLP in Q3 2026. In tandem, the company is conducting the stEPP study, a global observational study designed to further characterize disease burden, phototoxicity, sunlight exposure and plasma PPIX variability in patients with EPP and XLP.

Patient and Clinician Webinar Details

GondolaBio will host three webinars during the week of June 22, 2026 to share these data and development plans for PORT-77 with the patient and clinician communities. Details to register and/or access the webinars live are as follows:

• Clinician Webinars – Disease-Modifying Potential of PORT-77 in EPP: Clinical Data from the Phase 2a GATEWAY Study
  • Monday, June 22 at 4pm EDT in partnership with American Porphyrias Expert Collaborative (APEX), United Porphyrias Association. Register here.
  • Tuesday, June 23 at 7am EDT/12pm BST in partnership with International Porphyria Network (IPNET). Register here.
• Patient Webinar – Understanding New Research in EPP: What the Phase 2a GATEWAY Study Means for the Community
  • Saturday, June 27 at 11am EDT/4pm BST in partnership with the Global Porphyria Advocacy Coalition (GPAC). Save the date and join live here.

About Erythropoietic Protoporphyria and X-linked Protoporphyria

EPP and XLP, which affect greater than 25,000 people in the U.S. and EU, are genetic photodermatoses that result in the accumulation of protoporphyrin IX (PPIX). Affected patients experience cutaneous damage and excruciating pain when exposed to sunlight. Approximately 20-30% of patients with EPP/XLP will experience some type of liver damage with up to 5% of patients progressing to acute liver failure and requiring a liver transplant. There are no approved disease-modifying treatments available.

About PORT-77

PORT-77 is an oral, small molecule ABCG2 inhibitor currently in Phase 2 development for EPP and XLP. PORT-77 is designed to modify efflux of PPIX from the red blood cell to the plasma and from hepatocytes to the biliary tract, representing a potentially disease-modifying, leading treatment that addresses the root cause of EPP and XLP. The ongoing clinical program is designed to determine if PORT-77 can effectively reduce plasma PPIX to improve sunlight sensitivity and reduce liver damage.

About GondolaBio

GondolaBio is a clinical-stage biopharmaceutical company focused on developing novel medicines for patients living with genetic diseases. A sister company of BridgeBio Pharma, GondolaBio aims to leverage cutting-edge biological research to create breakthrough medicines addressing high unmet needs across multiple therapeutic areas, modalities, and stages ranging from early discovery to clinical development. Its team of experienced drug discoverers, developers and innovators are committed to translating advances in genetic science into medicines that can help patients as quickly as possible.