Qtorin Rapamycin Phase 2/3 Data Support First FDA-Approved Therapy for Rare Vascular Malformations

New clinical data from the phase 3 SELVA and phase 2 TOIVA studies suggest that Qtorin rapamycin (Palvella Therapeutics), a topical mechanistic target of rapamycin (mTOR) pathway inhibitor, may become the first FDA-approved treatment for microcystic lymphatic malformations (microcystic LMs) and cutaneous venous malformations (cutaneous VMs) — 2 rare, progressive vascular conditions with no currently approved pharmacologic options. The data were presented at the 2026 International Society for the Study of Vascular Anomalies (ISSVA) World Congress in Philadelphia, Pennsylvania.¹

"Data presented today at ISSVA further strengthen our conviction that QTORIN rapamycin has the potential to become the first FDA-approved therapy for microcystic lymphatic malformations and cutaneous venous malformations," said Wes Kaupinen, founder and Chief Executive Officer of Palvella, in the news release. Kaupinen noted that the company remains on track to file a New Drug Application (NDA) with the FDA in the second half of 2026, with potential approval targeted for the first half of 2027.¹

SELVA Phase 3 Trial: Design and Efficacy Findings

SELVA is a phase 3, single-arm, baseline-controlled clinical trial evaluating Qtorin 3.9% rapamycin anhydrous gel applied topically once daily over a 24-week efficacy evaluation period, followed by an open-label extension. The primary assessment instrument was the Microcystic Lymphatic Malformation Investigator Global Assessment (mLM-IGA), a disease-specific scale measuring clinician-rated global improvement.

Positive topline results were first announced in February 2026, with the study meeting its primary end point, key secondary end point, and all pre-specified secondary efficacy end points. Newly presented data at ISSVA expand on subgroup and patient-reported outcome findings. Among the 13 participants aged 6 to 11 years, 100% were rated "much improved" (+2) or "very much improved" (+3) on the mLM-IGA at week 24, with a mean improvement of +2.46 (p<0.001).¹

In participants with moderate or worse leaking or bleeding at baseline, manifestations described by the company as among the most debilitating features of the disease, 87% (20/23) achieved ratings of "much improved" or "very much improved" on the mLM-IGA Leaking/Bleeding subscale at week 24, with a mean improvement of +2.48 (p<0.001).¹

To assess design integrity, a blinded independent review evaluated disease stability during the 8-week pre-treatment run-in period. The mean change in the blinded Microcystic Lymphatic Malformation Multi-Component Static Scale (mLM-MCSS) score during this period was -0.1, followed by a mean improvement of -3.4 points after 24 weeks of active treatment, representing 48% of the maximum potential improvement from day 1.¹

Patient-reported outcomes were captured using the Treatment Satisfaction Questionnaire for Medication (TSQM-9). All 43 participants who completed the efficacy evaluation period reported at least some degree of satisfaction with therapy, with 84% reporting extreme, very high, or high satisfaction.¹

TOIVA Phase 2 Trial: Cutaneous Venous Malformations

TOIVA is a phase 2, single-arm, open-label, baseline-controlled trial assessing Qtorin rapamycin once daily for a 12-week efficacy evaluation period and a subsequent 12-week treatment extension. Positive topline results were first reported in December 2025.¹

At week 24, treatment demonstrated a mean reduction of 1.50 points in cVM-MCSS Height score (n=14; p<0.001) and 1.43 points in cVM-MCSS Appearance score (n=14; p<0.001), with improvements observed at all measured time points and an increasing clinical response associated with longer treatment duration.¹ Palvella has announced plans to initiate a phase 3 trial for this indication in the second half of 2026.¹

Clinical Context and Unmet Need

Microcystic LMs and cutaneous VMs are low-flow vascular malformations that arise from aberrant development of lymphatic and venous vessels, respectively. Both conditions are typically congenital, lifelong, and progressive, and can cause significant functional impairment, pain, disfigurement, and bleeding or fluid leakage. Currently, no FDA-approved pharmacotherapy exists for either condition, and management has historically relied on procedural interventions, compression, and supportive care.²

Mechanism of Action and Regulatory Background

Qtorin rapamycin is a topical formulation of rapamycin (sirolimus), an inhibitor of the mTOR pathway. Activating somatic mutations in the PI3K/AKT/mTOR signaling cascade have been identified as a molecular driver of vascular malformation pathogenesis, providing a biologic rationale for targeted mTOR inhibition.^3,4 The topical delivery approach is designed to concentrate drug activity in affected tissue while minimizing systemic absorption.

For the microcystic LM indication, Qtorin rapamycin has received FDA Breakthrough Therapy, Orphan Drug, and Fast Track designations, as well as an FDA Orphan Products Development grant. For cutaneous VMs, the compound holds FDA Fast Track Designation, and a Breakthrough Therapy Designation application has been submitted.¹

Interpretive Considerations

As with any single-arm study, these findings should be interpreted in the context of study design; both SELVA and TOIVA did not have placebo-controlled comparator arms, and the TOIVA cohort was smaller in size (n=14 at week 24). Peer-reviewed publication of the full datasets is ongoing, and phase 3 randomized trials for the VM indication are an important next step.¹

References

1. Palvella Therapeutics presents new SELVA and TOIVA data at the 2026 International Society for the Study of Vascular Anomalies World Congress supporting Qtorin rapamycin as a potential first-in-disease therapy for multiple serious, rare vascular malformations. News release. Palvella Therapeutics. May 20, 2026. Accessed May 21, 2026. https://ir.palvellatx.com/news-releases/news-release-details/palvella-therapeutics-presents-new-selva-and-toiva-data-2026
2. Garzon MC, Huang JT, Enjolras O, Frieden IJ. Vascular malformations: part I. J Am Acad Dermatol. 2007;56(3):353-370. doi:10.1016/j.jaad.2006.05.069
3. Limaye N, Kangas J, Mendola A, et al. Somatic activating PIK3CA mutations cause venous malformations. Am J Hum Genet. 2015;97(6):914-921. doi:10.1016/j.ajhg.2015.11.011
4. Adams DM, Trenor CC 3rd, Hammill AM, et al. Efficacy and safety of sirolimus in the treatment of complicated vascular anomalies. Pediatrics. 2016;137(2):e20153257. doi:10.1542/peds.2015-3257