Case study: Clinical trials in PHTS of medicines used to treat other conditions

Key facts

Type of study: Clinical trial of potential treatment for PHTS

Lead researcher study 1: Professor Mustafa Sahin

Institution: Boston Children’s Hospital, USA

Lead researcher study 2 : Dr Peter Stanich

Institution: Ohio State University, USA

What do we hope this research will tell us?

It is well established that PHTS is caused by an alteration in the PTEN gene, which results in the disruption of an important pathway in our cells, called mTOR, which is responsible for keeping cell division under control. This same pathway is also important for other conditions, including some non-inherited cancers, and there are existing medicines that act on this pathway that are already being used to treat patients with certain cancers. These medicines belong to a group known as “rapalogs”.

PTEN Research, with others, are funding exploratory clinical trials of two different rapalog medicines, looking at how they impact different characteristics of PHTS.

If these early clinical trials suggest the medicines may be helpful and are sufficiently safe, then larger scale clinical trials can be designed to provide the clinical information needed to allow doctors to be able to prescribe these medicines for people with PHTS.

What does it involve?

(Study 1) Cognitive difficulties clinical trial: Professor Mustafa Sahin, together with colleagues at Stanford University in California and the Cleveland Clinic in Ohio, are studying whether a medicine called everolimus is able to improve the cognitive difficulties that occur commonly in PHTS. These difficulties include things like problems with the amount of information an individual can hold in their short-term memory, or how long it takes to do a mental task. In total, 40 children and adults aged 5-45 years who have PHTS with cognitive symptoms have been enrolled into this clinical trial, each received 6 months of study treatment. Half of those taking part received everolimus, and half received dummy medicine that looks like everolimus, called placebo.

This trial has completed and the data has been analysed, and the results published. The results show that everolimus was well tolerated but larger studies are needed to better understand if it is truly safe and effective.

(Study 2) Polyposis clinical trial: Dr Peter Stanich is conducting a pilot study of a different medicine, called sirolimus, in PHTS patients with colon polyposis. Colon polyposis is the presence of multiple small growth (polyps) of non-cancerous tissue in the lower part of the digestive tract, and the clinical trial will see if sirolimus is able to reduce the number and size of these polyps. This study will involve 10 adults who will all be given sirolimus for one year.

This clinical trial is still looking for volunteers to take part, and more information about it can be found here.