mTOR inhibitors and renal angiomyolipomas (AMLs) in children

Kidney health is a serious concern for many people living with TSC. Renal cysts and angiomyolipomas (AMLs) often develop.  These can obliterate healthy renal tissue and cause bleeding as they grow, leading to chronic kidney disease or devastating bleeding complications.

Approximately 50% of children with TSC have a renal AML and the incidence increases with age. This study researches the use of mTOR inhibitor treatments for children with renal AMLs.

The need for this study

The mTOR inhibitors everolimus and sirolimus are now relatively well established in the treatment of renal AMLs in adults with TSC.  Despite this, to date the published research on mTOR inhibitor use in paediatric TSC-AML remains very limited. This study’s objectives were to investigate the behaviour of renal AMLs in children with TSC who were placed on mTOR inhibitor therapy, as well as to describe medication tolerability.

About this study

There were initially nineteen children in this study, eighteen were prescribed everolimus only and one was prescribed everolimus, then sirolimus after a three-year hiatus off the medication.  Seven patients (36%) reported a side effect, though in four of these patients there was only a mild effect, which either resolved or was tolerated. Three patients (16%) stopped the medication due to intolerable side effects. These included recurrent mouth ulcers, gastrointestinal upset, and recurrent upper respiratory tract infection.

Study results

The final study results included just fifteen patients, twelve of whom (80%) had AML at the start of the mTOR inhibitor treatment. The good news is that in all twelve of those patients, the AML remained either unchanged in size (33%) or decreased in size (67%). And, no patient experienced an increase in the size of their AML.

None of the three patients without an AML developed an AML during the treatment.

In this small study, the efficacy and tolerability profile of mTOR inhibitors in treating children with renal AMLs appears similar to the published research on adult patients.  The authors say that everolimus use may be most favourable in children older than age 11 years with the highest risk AMLs and/or with AML ≥2 cm, as this is where the treatment appears to confer the greatest absolute size reduction.

However, the authors also state that more research is needed into potentially detrimental effects of the treatment such as puberty suppression.  And, whilst the results are encouraging, it must be remembered that this was a very small scale study.

For more on the use of mTOR inhibitors to treat renal AMLs see https://tsa.org.au/mtor-inhibitors-in-tsc/

Wu, C. Q., Wolf, D. S., & Smith, E. A. (2020). Fate of Pediatric Renal Angiomyolipoma During mTOR Inhibitor Treatment in Tuberous Sclerosis Complex. Urology. DOI: 10.1016/j.urology.2019.12.041

Full paper available at:  https://www.goldjournal.net/article/S0090-4295(20)30175-8/fulltext

DISCLAIMER

This information is intended to provide some insights into recent TSC-related research.  It is not intended to, and it should not, constitute medical or other advice.  Readers are warned not to take any action without first seeking medical advice.