Reversion of resistance to mTOR inhibitors with the addition of exemestane in patients with malignant PEComa

Abstract

Abstract Background Perivascular epithelioid cell tumors (PEComa) are exceedingly rare mesenchymal neoplasms arising in a variety of anatomic sites. mTOR inhibitors are active in these neoplasms. However, no other effective treatments are available in those patients progressing to them. The PI3K–Akt–mTOR signaling pathway modulates neoplastic growth through signaling activation of ER and the EGF receptor family of receptor tyrosine kinases. ER drives PI3K/AKT activation in response to mTORC1 inhibition. This provides a rationale for combining anti-estrogens and mTORC1 inhibitors. Methods We retrospectively identified patients with advanced PEComa treated with mTOR inhibitors since January 2002 at Fondazione IRCCS Istituto Nazionale dei Tumori, Milan – Italy. In a subgroup of them, exemestane was added at the time of progression. Results Twenty-eight patients with advanced PEComa treated with mTOR inhibitors were identified. Twenty–six were evaluable for response. Twelve out 26 (46%) had a PR and seven (27%) a SD, with a median PFS of 7 months. At the time of progression to sirolimus, 5 patients received a combination of sirolimus and exemestane and one of sirolimus, exemestane and GnRH. Three patients out 6 had a PR, 2 out 6 had a SD, and 1 out 6 had a PD, with a median PFS of 6 months. In this subgroup of patients treated with the combination, previous PFS to mTOR inhibitors was 6.6 months. Conclusions In this small retrospective series, the combination of mTOR inhibitors and exemestane obtained a reversion of resistance to mTOR inhibitors in one half of patients. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure R. Sanfilippo: Honoraria (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: Lilly; Honoraria (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: PharmaMar; Research grant / Funding (institution): Advanchen Laboratories; Research grant / Funding (institution): Amgen Dompe; Research grant / Funding (institution): AROG Pharmaceuticals; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): Blueprint Medicines; Research grant / Funding (institution): Daiichi Sankyo; Research grant / Funding (institution): Deciphera; Research grant / Funding (institution): Eisai; Research grant / Funding (institution): Epizyme Inc; Research grant / Funding (institution): Galxo; Research grant / Funding (institution): Karyopharm; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Pfizer. C. Fabbroni: Research grant / Funding (institution): Advanchen Laboratories; Research grant / Funding (institution): Amgen Dompe’; Research grant / Funding (institution): AROG Pharmaceuticals; Research grant / Funding (institution): bayer; Research grant / Funding (institution): Blueprint Medicines; Research grant / Funding (institution): Daiichi Sankyo; Research grant / Funding (institution): Deciphera; Research grant / Funding (institution): Eisai; Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Epizyme Inc; Research grant / Funding (institution): Glaxo; Research grant / Funding (institution): Karyopharm Pharmaceuticals; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Pfizer; Research grant / Funding (institution): PharmaMar. E. Fumagalli: Research grant / Funding (institution): Advenchen Laboratories; Research grant / Funding (institution): Amgen dompe’; Research grant / Funding (institution): AROG Pharmaceuticals; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): Blueprint Medicines; Research grant / Funding (institution): Daiichi Sankyo; Research grant / Funding (institution): Deciphera; Research grant / Funding (institution): Eisai; Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Epizyme; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): PharmaMar; Research grant / Funding (institution): Glaxo; Research grant / Funding (institution): karyopharm Pharmaceuticals; Research grant / Funding (institution): Pfizer. R. Bertulli: Research grant / Funding (institution): Karyopharm Pharmaceuticals; Research grant / Funding (institution): Pfizer; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Eisai; Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Advenchen Laboratories; Research grant / Funding (institution): Amgen dompe’; Research grant / Funding (institution): AROG Pharmaceuticals; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): Blueprint Medicines; Research grant / Funding (institution): Daiichi Sankyo ; Research grant / Funding (institution): Deciphera; Research grant / Funding (institution): Epizyme; Research grant / Funding (institution): Glaxo; Research grant / Funding (institution): PharmaMar. S. Stacchiotti: Research grant / Funding (institution): Karyopharm Pharmaceuticals; Research grant / Funding (institution): Eisai; Research grant / Funding (institution): PharmaMar; Research grant / Funding (institution): Glaxo; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Deciphera; Research grant / Funding (institution): Advenche Laboratories; Research grant / Funding (institution): Amgen; Research grant / Funding (institution): AROG Pharmaceuticals; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): Blueprint Medicines; Research grant / Funding (institution): Daiichi Sankyo; Research grant / Funding (institution): Epizyme; Research grant / Funding (institution): Pfizer. P.G. Casali: Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Bayer; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Deciphera; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Eisai; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Lilly; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Pfizer; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Nektar Therapeutics; Research grant / Funding (institution): Advenchen Laboratories; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Blueprint Midicines; Research grant / Funding (institution): AROG Pharmaceuticals; Research grant / Funding (institution): Amgen dompe’; Research grant / Funding (institution): Daiichi Sankyo; Research grant / Funding (institution): Epizyme; Research grant / Funding (institution): Glaxo; Research grant / Funding (institution): KaryopharmPharmaceuticals; Research grant / Funding (institution): PharmaMar. All other authors have declared no conflicts of interest.