# Mifepristone

Source: https://onco.cc/drugs/mifepristone/  
OnCo record `mifepristone` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Mifepristone, best known as an abortion pill and a treatment for Cushing's syndrome, blocks progesterone receptors that most meningiomas carry. A large phase 3 trial found it did not slow inoperable meningiomas.

## Summary

Mifepristone is a synthetic steroid that antagonises the progesterone receptor and, at high doses, the glucocorticoid receptor; it is licensed for medical termination of pregnancy and for hyperglycaemia in Cushing's syndrome. Because around 70 percent of meningiomas express progesterone receptors and grow faster in pregnancy, small series in the 1990s suggested antiprogestin therapy might control unresectable tumours.

The SWOG S9005 phase 3 trial randomised 164 patients with unresectable meningioma to mifepristone 200 mg daily or placebo for up to two years; there was no difference in failure-free or overall survival (Journal of Clinical Oncology, 2015). The meningioma page lists it with hydroxyurea, somatostatin analogues and interferon among the systemic treatments that failed.

## Fields

- Kind: Treatment
- Status: negative
- Last checked: 2026-09-17
- Also known as: RU-486; RU486
- Tags: subtype-drugs-wave
- Modality: Oral progesterone and glucocorticoid receptor antagonist
- Mechanism: Blocks the progesterone receptor, which most meningiomas express, and at higher doses the glucocorticoid receptor; the hope was that removing progesterone drive would slow the tumours.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Mifepristone
- Wikipedia: https://en.wikipedia.org/wiki/Mifepristone

## Connected records

- cancers: [Meningioma](https://onco.cc/cancers/meningioma/)

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JSON: https://onco.cc/api/v1/entities/mifepristone.json