FP21-5 Endometrial Effects of Long-Term Mifepristone (MIFE) Treatment of Cushing's Syndrome: Results From the Seismic Studies

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: FP21-HPA Axis: New Clinical Developments
Clinical
Sunday, June 16, 2013: 10:45 AM-11:15 AM
Presentation Start Time: 11:05 AM
Room 134 (Moscone Center)

Poster Board SUN-52
Ty Brian Carroll*1, Olga Ioffe2, Irving M Spitz3, Coleman Gross4, David Cram5 and Amir Hekmat Hamrahian6
1Medical College of Wisconsin, Milwaukee, WI, 2University of Maryland, Baltimore, MD, 3Inst of Hormone Res, Jerusalem, Israel, 4Corcept Therapeutics, Berkeley, CA, 5Corcept Therapeutics, Menlo Park, CA, 6Cleveland Clinic Foundation, Chargrin Falls, OH
Background: Administration of MIFE may be associated with endometrial thickening, vaginal bleeding and a histological pattern known as progesterone receptor modulator associated endometrial changes (PAEC).  We evaluated the endometrial effects of long-term MIFE in Cushing’s syndrome (CS).

Methods: Twenty-six pre- (preM) and 9 post-menopausal (postM) female CS patients (pts) enrolled in the SEISMIC study and its extension received MIFE 300-1200 mg qd for a median 17.3  months (mo) [range:0.4-44.6]. Transvaginal ultrasounds (TVUS) were performed at baseline, mo 6 and then every 3 mo. Vaginal bleeding episodes were collected by adverse event reporting.  Endometrial biopsies, obtained in 11 preM and 4 postM pts, were evaluated using a standardized system by a pathologist expert in PAEC (O.I.).

Results: Median [range] endometrial thickness (ET) for preM and postM pts was 5.0 [1.0-13.0] and 3.0 [2.0-8.0] mm at baseline vs 11.0 [4.8-55.0](P<0.01) and 6.4 [1.0-17.0] mm (P=0.25) at 6 mo, respectively. ET increases of >5mm occurred in 8 preM and 1 postM; increases >10 mm occurred in 4 preM and 1 postM.  During extended follow-up in 18 pts (median of 26.9 [13.7-43] mo) there were continued increases in ET; median maximal ET in preM (N=12): 13.5 [3-38] mm (P=0.014); postM (N=6): 8 [5-17] mm (P=0.04).   Bleeding occurred in 10 preM and 2 postM.  Minor bleeding occurred upon MIFE start in 4 preM.  Clinically relevant bleeding occurred at 14 to 24 weeks of treatment in 4 preM with ET>20 mm (median 38 [25-55] mm).  Endometrial thickening was not uniformly accompanied by bleeding: there was no bleeding in 3 pts with ET > 20mm beyond 6 mo.  Biopsies showed PAEC with benign inactive or atrophic endometrium. One pt demonstrated simple hyperplasia that could not be confirmed on a repeat sample.   Complex atypical endometrial hyperplasia was noted in a second pt and was thought to have existed prior to study entry. None had endometrial carcinoma.

Conclusion:  MIFE use was associated with endometrial thickening on TVUS and was more prominent in preM. ET of >20 mm may lead to problematic clinical bleeding in some pts. Endometrial morphology was similar to that of other progesterone receptor modulators and that reported for MIFE at dosages that do not produce an antiglucocorticoid effect.  TVUS may be useful to identify pts with very thickened endometria who may be at risk of clinically significant bleeding during chronic MIFE therapy, especially in the first 6 mo of treatment.

Disclosure: TBC: Researcher, Corcept, Speaker, Corcept. OI: Independent Contractor (including contracted research), Corcept. IMS: Consultant, Corcept. CG: Employee, Corcept. DC: Employee, Corcept. AHH: Consultant, Corcept.

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: Corcept Therapeutics