Those living with rare diseases or conditions often face difficulty in finding treatment options – or even spurring researchers to make headway within their disease states. To combat this and incentivize drug developers, the FDA created the Orphan Drug Act. Orphan Drug designation is now granted to drugs or biologics intended to treat, diagnose, or prevent rare diseases (those affecting fewer than 200,000 Americans). As a benefit, drug developers whose therapies receive this designation earn fee waivers, tax credits, and seven years of market exclusivity upon approval. On June 20, 2022, OncLive reported that paxalisib received Orphan Drug designation for the potential treatment of atypical teratoid rhabdoid tumors (AT/RT).
Currently, therapeutic options available for AT/RT are limited. Thus, paxalisib has the potential to fill an unmet need for this patient population.
About Atypical Teratoid Rhabdoid Tumors (AT/RT)
An atypical teratoid rhabdoid tumor (AT/RT) is a rare and highly malignant tumor which forms in the brain and spinal cord. These tumors grow quickly, lending to the poor survival rate associated with AT/RT. Sporadic INI1 mutations often cause these tumors. However, SMARCA4 and SMARCB1 gene mutations have also been associated with an increased risk. AT/RT most often forms in children under age 3, though they can form in older individuals. Signs and characteristics vary based on the child’s age, as well as where the tumor formed. Potential symptoms can include:
- Nausea and vomiting
- Increasing head size in infants
- A morning headache or headaches which disappear after vomiting
- Difficulty walking
- Asymmetric eye or facial movements
- Poor balance and coordination
- Abnormal sleepiness
Paxalisib: An Overview
According to Kazia Therapeutics, paxalisib was first developed by Genentech, Inc. Kazia Therapeutics entered into an exclusive licensing agreement with Genentech in 2016. Kazia Therapeutics explains that paxalisib:
inhibits PI3K, a critical control mechanism in growth and cell division, which is activated in many forms of cancer. Paxalisib has been designed to cross the blood-brain barrier and a wealth of experimental data shows that it does so very successfully.
Initially, paxalisib was developed as a therapy for those with glioblastoma. It has since received both Fast Track and Orphan Drug designations for this indication, as well as Orphan Drug designation for glioma. Therefore, researchers believe that it might also be helpful in treating AT/RT.
Currently, researchers are evaluating paxalisib in a variety of clinical trials. These include a Phase 2 clinical trial involving patients with gliomas, a Phase 1 clinical trial involving patients with diffuse intrinsic pontine gliomas, and a Phase 2/3 clinical trial involving patients with glioblastoma.
