Introduction To date, there is no proven licensed systemic treatment for neurofibromatosis type 2 (NF2)-related schwannomatosis patients. There is a need for more effective, less toxic treatments and, as a rare disease, NF2 is often overlooked in targeted drug development.
Subcutaneous schwannomas of the skin (CS) are common in the NF2 population. This trial involves the repurposing of medications already licensed for HIV - ritonavir and lopinavir (Kaletra and Norvir) - that have been shown to reduce tumour growth by reducing cell proliferation in human schwannoma and meningioma tumour cell cultures.
The safety and tolerability of these drugs are already known, so they are safe candidates to trial in NF2 patients. Methods and analysis This trial is an open-label, phase 0 design.
A maximum of 16 participants diagnosed with NF2-related schwannomatosis will be enrolled in this study. Treatment duration is 30 days, with a 30-day follow-up.
Biopsies and blood samples will be collected to assess whether the drugs reach the tumours and to analyse the tumour-cell response.
BMJ Open published a clinical update in Research Highlights on 16 Jun 2026.
The item focuses on Repurposing anti-retroviral drugs to treat NF2-related tumours: a protocol for a phase 0 trial (RETREAT).
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