FDA Grants Rolling Review for QTORIN Rapamycin Amid Scrutiny of Expedited Pathways
FDA granted rolling review for Palvella's QTORIN rapamycin NDA. Also covered: global expedited approval pathways, accelerated approval scrutiny, and multi-regional CDx strategies.
The US Food and Drug Administration (FDA) has granted rolling review for Palvella Therapeutics' New Drug Application (NDA) for QTORIN™ rapamycin for the treatment of microcystic lymphatic malformations (microcystic LMs). Rolling review is an FDA regulatory feature available to programs with Fast Track or Breakthrough Therapy designation and is intended to facilitate expedited FDA review of applications for therapies addressing serious conditions with unmet medical need. Palvella remains on track to complete submission of the QTORIN™ rapamycin NDA in the second half of 2026.
QTORIN™ rapamycin has received Breakthrough Therapy, Orphan Drug and Fast Track designations from FDA for the treatment of microcystic LMs. There are no FDA-approved treatments for the estimated 30,000 or more people diagnosed with microcystic LMs in the United States. Microcystic LMs are a rare, chronically debilitating genetic disease driven by dysregulation of the PI3K/mTOR pathway.
The FDA's accelerated approval pathway has come under increasing scrutiny from regulators, policymakers, and independent reviewers, reflecting broader questions about how speed, evidence generation, and public trust should be balanced. Regulatory agencies worldwide offer numerous expedited approval pathways, including the FDA's Fast Track and Breakthrough Therapy designations, a new National Priority Voucher programme introduced in 2025, the European Medicines Agency's PRIME priority medicines designation, and Japan's Pharmaceuticals and Medical Devices Agency (PMDA) Sakigake programme.
Expedited pathways such as Fast Track, Breakthrough Therapy, and Accelerated Approval allow faster access to medicines that address serious conditions or unmet medical needs, while maintaining rigorous safety standards. The COVID-19 pandemic demonstrated what is possible when regulatory systems evolve. NRAs and the biopharmaceutical industry adopted flexible and iterative approaches to accelerate the development, evaluation, authorization, and distribution of vaccines and diagnostics. These regulatory agilities included the use of digital tools, decentralized clinical trials, and rolling reviews of data. A key enabler of this speed was regulatory reliance, under which one regulatory authority considers and gives significant weight to the scientific assessments or approvals of another trusted authority, such as the World Health Organization.
The FDA sees drug repurposing as an untapped resource that could help address unmet medical needs across a range of diseases and conditions.
As precision medicine expands globally, navigating the complex regulatory landscape for companion diagnostics (CDx) has become critical for successful pharma partnerships. Regulatory experts from Burning Rock and Riken Genesis have shared strategies for achieving multi-regional CDx approvals, including aligning CDx development with FDA, EMA, and NMPA requirements. A case study on the Japanese approval of OncoScreen Plus as a CDx for AstraZeneca's capivasertib highlighted PMDA expectations for imported CDx products.
For therapies using accelerated pathways, the need for manufacturing and supply readiness happens much earlier than expected. Integrated development strategies that combine formulation, manufacturing, and flexible clinical dosing have been proven to help de-risk early phase trials. In silico predictive tools, such as modelling and simulation, can assist in selecting suitable dose forms and forecasting critical parameters like pharmacokinetic profiles. Refined scale-up strategies prioritise flexibility and just-in-time production.