PORT-77
An investigational treatment for Erythropoietic Protoporphyria.
The same compound appears under different names depending on the context. Here is how to identify PORT-77 wherever you encounter it, plus the key facts at a glance.
- Generic name
- PORT-77
- Development code
- PORT-77
- Drug class
- ABCG2 transporter inhibitor
- Manufacturer
- Portal Therapeutics (GondolaBio)
- How it's taken
- Oral, once or twice daily (tablets in PATHWAY; an oral suspension was used in the Phase 2a study)
An investigational daily pill from Portal Therapeutics, a GondolaBio company, that blocks the ABCG2 transporter so less protoporphyrin reaches the plasma. In a 4-day Phase 2a study it lowered plasma protoporphyrin by 63% to 79%, and the Phase 2b/3 PATHWAY trial is recruiting adults and adolescents at US sites.
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Where PORT-77 fits
PORT-77 is the earliest of the 3 oral EPP drugs and the only one that works on transport of protoporphyrin rather than its production or on skin pigment. Its claim so far is a fast, large drop in plasma protoporphyrin over 4 days; whether that means more pain-free sunlight or less liver damage is what PATHWAY is designed to test.
How PORT-77 works
In EPP and XLP, red blood cells make too much protoporphyrin IX and release it into the plasma, from where it reaches the skin and the liver. ABCG2 is the export pump that moves protoporphyrin out of red cells and, in the liver, out of liver cells into bile[1]. PORT-77 blocks ABCG2. The company's reasoning is that keeping protoporphyrin inside red cells, where light cannot reach it, lowers the plasma level that drives skin pain, and that changing the flow through the liver may reduce liver damage[1].
In the Phase 2a study plasma protoporphyrin fell within hours of the first dose and did not rebound after dosing stopped[1]. Whether the retained protoporphyrin has effects of its own over months of treatment is one of the questions for the longer trials.
Mechanism: Oral small molecule inhibitor of ABCG2, the transporter that moves protoporphyrin IX out of red blood cells into plasma and out of liver cells into bile
Side effects and safety
GondolaBio reported that PORT-77 was well tolerated in the 4-day Phase 2a study, with no serious adverse events, no treatment discontinuations and no tolerability signals, and a lower rate of treatment-emergent adverse events during the PORT-77 period than during the placebo period[1]. Those are 4 days of dosing in 19 adults; safety over months and in adolescents is a primary outcome of PATHWAY[2]. No percentages by event have been published.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking PORT-77
In the Phase 2a GATEWAY study, participants took an oral suspension of 180 mg once daily or 300 mg twice daily for 4 days after a placebo period[1]. PATHWAY uses oral tablets at 2 dose levels in its Phase 2b part, after which 1 dose goes forward into the Phase 3 part and an open-label extension[2]. The final dose and form would be set by the FDA label if the drug is approved.
How EPP and XLP treatments compare
Scenesse is the only FDA-approved treatment for erythropoietic protoporphyria, and it is approved for adults. Behind it are 3 oral drugs at different stages: dersimelagon is under FDA review, bitopertin received a complete response letter and finished its Phase 3 trial, and PORT-77 is recruiting for a Phase 2b/3 trial. Scenesse and dersimelagon work on skin pigment; bitopertin and PORT-77 try to lower protoporphyrin itself. None has been compared head to head.
Erythropoietic Protoporphyria has 1 FDA-approved treatment: Scenesse (afamelanotide, approved 2019). Also compared, not FDA-approved for erythropoietic protoporphyria: Dersimelagon (MT-7117) (dersimelagon, Under FDA priority review, decision by end of February 2027); Bitopertin (DISC-1459) (bitopertin, Complete response letter February 13, 2026; Phase 3 APOLLO topline due October 19, 2026); PORT-77 (PORT-77, Phase 2b/3 recruiting; not yet reviewed by the FDA). Scenesse is typically used as adults with a history of phototoxic reactions from epp.
| Drug | How it works | How it’s given | How often | Where you get it | Who it is for | FDA status |
|---|---|---|---|---|---|---|
Scenesse afamelanotide | MC1R agonist: a peptide that switches on eumelanin production so the skin absorbs light before it reaches protoporphyrin | Dissolving 16 mg implant placed under the skin above the hip | Every 2 months | Clinuvel-accredited EPP Specialty Center (about 120 in North America) | Adults with a history of phototoxic reactions from EPP | 2019 |
Dersimelagon (MT-7117) dersimelagon | MC1R agonist: a small molecule with the same pigment target as Scenesse | Oral tablet | Once daily (200 mg in Phase 3) | Home, if approved | Studied in people aged 12 to under 75 with EPP or XLP | Under FDA priority review, decision by end of February 2027 |
Bitopertin (DISC-1459) bitopertin | GlyT1 inhibitor: slows heme production in developing red cells so less protoporphyrin is made | Oral tablet | Once daily (60 mg in Phase 3 and expanded access) | Home; US expanded access program for ages 12 and up without satisfactory options | Studied in people aged 12 and up with EPP or XLP | Complete response letter February 13, 2026; Phase 3 APOLLO topline due October 19, 2026 |
PORT-77 PORT-77 You are here | ABCG2 inhibitor: blocks the pump that moves protoporphyrin out of red cells into plasma | Oral tablet | Once or twice daily (dose being chosen in Phase 2b) | Clinical trial sites in the US | Recruiting people aged 12 and up with EPP or XLP for PATHWAY | Phase 2b/3 recruiting; not yet reviewed by the FDA |
Only Scenesse is FDA approved. Dersimelagon, bitopertin and PORT-77 are investigational and their results come from company announcements and trial registrations, not FDA labels; the FDA has not reviewed PORT-77 and declined bitopertin's first application. Trial results for different drugs measured different things over different periods and cannot be compared directly. Talk with a porphyria specialist about what fits your age, your liver and iron tests and your access to an accredited center.
Clinical trial results
GATEWAY (NCT06971900) was a blinded, randomized, placebo-controlled crossover Phase 2a study in adults with EPP in the US. In it, 19 enrolled participants received placebo followed by PORT-77 180 mg once daily or 300 mg twice daily for 4 days; the registry lists 28 enrolled, a figure that is not explained in the company release. Mean plasma protoporphyrin fell 79% on 300 mg twice daily and 63% on 180 mg once daily, within hours, with no rebound after stopping, and the effect was consistent across baseline levels from 8 to 121 micrograms per deciliter[1][3].
The results were presented at the European Hematology Association congress in June 2026[1].
PATHWAY (NCT07820085) is a Phase 2b/3, quadruple-blind, randomized, placebo-controlled trial with an open-label extension in people aged 12 and up with EPP or XLP, planned for 225 participants, recruiting at US sites with primary completion estimated for March 2029[2]. Part 1 (Phase 2b) picks the dose by plasma protoporphyrin and safety; Part 2 (Phase 3) tests whether PORT-77 lowers protoporphyrin and increases daily time in sunlight without pain compared with placebo; Part 3 is the extension[2].
GondolaBio said the design followed general alignment with the FDA at an End-of-Phase 2 meeting in June 2026[1]. Portal is also running stEPP (NCT07567131), an observational study of 50 adults and adolescents with EPP and XLP to measure disease burden, phototoxicity, sunlight exposure and plasma protoporphyrin variability[1].
Development history
Portal Therapeutics is an affiliate of GondolaBio, a Palo Alto company that is a sister company of BridgeBio Pharma[1]. The FDA granted PORT-77 Orphan Drug and Fast Track designations for EPP and XLP in October 2025[1].
GondolaBio announced the GATEWAY results on June 22, 2026, held clinician webinars with the American Porphyrias Expert Collaborative, the United Porphyrias Association and the International Porphyria Network, and a patient webinar with the Global Porphyria Advocacy Coalition, and announced PATHWAY as its next step[1]; the trial record was first posted on ClinicalTrials.gov in September 2026 and lists the study as recruiting at US sites.
The PATHWAY record was first posted on ClinicalTrials.gov in September 2026 and is listed as recruiting[2]. PORT-77 has not been reviewed for approval by any regulator.
Explore Erythropoietic Protoporphyria trials
Other Erythropoietic Protoporphyria treatments
PORT-77 is behind dersimelagon (under FDA review) and bitopertin (Phase 3 complete) in development. All 3 are pills; PORT-77 and bitopertin aim at protoporphyrin and dersimelagon at skin pigment, the approach of the approved implant Scenesse.
Where to access PORT-77
Investigational: available only through clinical trial enrollment
PORT-77 has not been approved by the FDA and is not available by prescription. The only way for a patient to receive PORT-77 today is by enrolling in an active clinical trial and meeting that trial's eligibility criteria. Decisions about trial participation should be made with the specialist who manages the patient's condition and knows their current treatment.
Primary active trial
ClinicalTrials.gov record NCT07820085
View full trial record on ClinicalTrials.gov →Trial status, site list, and eligibility are pulled from ClinicalTrials.gov. Confirm current recruitment status and nearest site directly with the study team before traveling.
Common questions about PORT-77
▸What is PORT-77?
An investigational daily pill from Portal Therapeutics, a GondolaBio company, that blocks the ABCG2 transporter so less protoporphyrin reaches the plasma. In a 4-day Phase 2a study it lowered plasma protoporphyrin by 63% to 79%, and the Phase 2b/3 PATHWAY trial is recruiting adults and adolescents at US sites.
▸How does PORT-77 work?
In EPP and XLP, red blood cells make too much protoporphyrin IX and release it into the plasma, from where it reaches the skin and the liver. ABCG2 is the export pump that moves protoporphyrin out of red cells and, in the liver, out of liver cells into bile[1]. PORT-77 blocks ABCG2. The company's reasoning is that keeping protoporphyrin inside red cells, where light cannot reach it, lowers the plasma level that drives skin pain, and that changing the flow through the liver may reduce liver damage[1]. In the Phase 2a study plasma protoporphyrin fell within hours of the first dose and did not rebound after dosing stopped[1]. Whether the retained protoporphyrin has effects of its own over months of treatment is one of the questions for the longer trials.
▸What are the side effects of PORT-77?
GondolaBio reported that PORT-77 was well tolerated in the 4-day Phase 2a study, with no serious adverse events, no treatment discontinuations and no tolerability signals, and a lower rate of treatment-emergent adverse events during the PORT-77 period than during the placebo period[1]. Those are 4 days of dosing in 19 adults; safety over months and in adolescents is a primary outcome of PATHWAY[2]. No percentages by event have been published.
▸How is PORT-77 taken?
In the Phase 2a GATEWAY study, participants took an oral suspension of 180 mg once daily or 300 mg twice daily for 4 days after a placebo period[1]. PATHWAY uses oral tablets at 2 dose levels in its Phase 2b part, after which 1 dose goes forward into the Phase 3 part and an open-label extension[2]. The final dose and form would be set by the FDA label if the drug is approved.
▸Is PORT-77 FDA approved?
PORT-77 is currently in phase 2 clinical trials for Erythropoietic Protoporphyria. It has not yet received FDA approval.
▸What is PORT-77 and how does it work?
An investigational daily pill that blocks ABCG2, the pump that moves protoporphyrin out of red blood cells into the plasma.
Goal: keep protoporphyrin where light cannot reach it and change how it passes through the liver.
Result so far: plasma protoporphyrin fell 63% to 79% within hours in a 4-day study.
Source: GondolaBio, June 22, 2026
▸Is the PORT-77 PATHWAY trial recruiting?
Yes, at US sites, as of the ClinicalTrials.gov record updated September 15, 2026.
Who: people aged 12 and up with EPP or XLP; 225 planned.
Design: a dose-finding Phase 2b part, then a Phase 3 part against placebo, then an open-label extension.
Source: ClinicalTrials.gov NCT07820085
▸Does PORT-77 let people stay in the sun longer?
That has not been tested yet.
What is known: a large, fast drop in plasma protoporphyrin over 4 days in 19 adults.
What PATHWAY measures: average daily time in sunlight without pain, plasma protoporphyrin and safety.
Source: GondolaBio, June 22, 2026; ClinicalTrials.gov NCT07820085
▸Who makes PORT-77?
Portal Therapeutics, an affiliate of GondolaBio in Palo Alto, California, which is a sister company of BridgeBio Pharma.
Designations: FDA Orphan Drug and Fast Track for EPP and XLP, granted October 2025.
Source: GondolaBio, June 22, 2026
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- GondolaBio · 2026-06-22. GondolaBio Announces Positive Phase 2a Results Demonstrating 79% Plasma Protoporphyrin IX Reduction and Disease-Modifying Potential of PORT-77 for Erythropoietic Protoporphyria. https://gondolabio.com/gondolabio-announces-positive-phase-2a-results-demonstrating-79-plasma-protoporphyrin-ix-reduction-and-disease-modifying-potential-of-port-77-for-erythropoietic-protoporphyria/
- ClinicalTrials.gov · 2026-09-15. A Study to Investigate PORT-77 Oral Dosing Compared With Placebo in Participants With EPP or XLP (PATHWAY). https://clinicaltrials.gov/study/NCT07820085
- ClinicalTrials.gov · 2026-07-29. GATEWAY: A Phase 2a Study of PORT-77 in Adults With Erythropoietic Protoporphyria. https://clinicaltrials.gov/study/NCT06971900