Effects of aglepristone, a progesterone receptor antagonist, in a dog with a vaginal fibroma

Abstract

A 12-year-old, entire, nulliparous crossbreed female dog was presented with a history of vulval bleeding, bulging of the perineum and faecal tenesmus. A firm, non-painful perineal mass, measuring 9.11x5.4 cm, with erythema was detected. Abdominal radiography showed compression and elevation of the rectal ampulla. A dose of 10 mg/kg aglepristone was administered subcutaneously on days 1, 2, 8, 15, 28 and 35. An incision biopsy was taken on day 15 and immunohistochemical analysis showed that the majority of neoplastic cells expressed progesterone receptors. Both the cutaneous erythema and the faecal tenesmus had resolved by day 28. A 50 per cent reduction in size was observed by day 60 (surgical excision). This study shows that benign tumours of the vagina of the dog that contain progesterone receptors can be reduced in size in a palliative or neoadjuvant setting using the progesterone receptor antagonist aglepristone.

Effects of the Anti‐Progestin Aglepristone on the Uterine Tissue of Cats Administered Medroxyprogesterone Acetate

“…The antagonism to the action of progesterone in regression of the mammary tissue has been reported in cats developing fibroadenomatous hyperplasia, when aglepristone is given at 10 mg ⁄ kg on four to five consecutive days (Wehrend et al 2001). In a dog with a vaginal fibroma, aglepristone reduced the size of the tumour mass without lowering the proliferative rates of the tumour cells demonstrated by the proliferation marker Ki67 (Rollo´n et al 2008). Perhaps in this study, a significant anti-progestational effect would have been noted if tissues were obtained earlier than 14 days after anti-progestin treatment.…”

“…2001). In a dog with a vaginal fibroma, aglepristone reduced the size of the tumour mass without lowering the proliferative rates of the tumour cells demonstrated by the proliferation marker Ki67 (Rollón et al. 2008).…”

“…Moreover, although its mechanism has not been clearly elucidated, aglepristone has been successfully used to treat progesterone-dependent benign tumour mass, i.e. fibroadenomatous mammary hyperplasia in cats (Wehrend et al 2001;Go¨rlinger et al 2002) and vaginal fibroma in dogs (Rollo´n et al 2008). Low doses of the anti-progestin (RU486) administered chronically to women have inhibited glandular mitosis and induced stromal compaction in the endometrium, demonstrating the anti-proliferative effect of this progesterone antagonist (Cameron et al 1996).…”

Sex Steroid Hormones and Tumors in Domestic Animals

“…Once the IHC analysis revealed the presence of sex steroid hormones receptors in mammary tumours, several studied analyzed their value as favourable prognostic indicators [18,[20][21][22][23][24][25] adding new data to the well-known similari-ties between and human and animal mammary tumours [26]. However, the important role of ER and PR as predictive factors of response to endocrine treatment of breast cancer has been rarely analyzed in animal tumours although recent studies based on the blockade of PR in canine mammary carcinomas and reproductive tract tumours of female and male dogs and cats support their value in the control of these diseases [27][28][29][30].…”

Lack of in vitro effect of aglepristone on IFN-γ and IL-4 production by resting and mitogen-activated T cells of luteal bitches

“…Currently, aglepristone is used for induction of parturition and in the treatment of canine and feline pyometra [2]. Recently, there were also attempts to use aglepristone in the therapy of progesterone-dependent disorders in dogs, such as: growth hormone excess [3], vaginal fibroma [4] and mammary gland carcinoma [5]. …”