The US FDA approved an investigator initiated phase II 40 patient study to treat patients with stage IIIB or IV non-small cell lung cancer who have progressed despite a minimum of 2 rounds of chemo or immunotherapy with the progesterone receptor modulator mifepristone taken orally at 300mg/day (www.clinicaltrials.gov). The first patient in the study reported at the 2017 AACR meeting with stage IV lung cancer with brain metastasis has had non-progressive disease with excellent quality of life (ECOG-zero) after 24 months on mifepristone therapy. His lung cancer was PD-L1 negative, and thus he did not receive check-point inhibitors. We report, herein, the clinical outcome of the second patient with stage IV disease who not only progressed despite 3 chemotherapy regimens but also nivolumab (she was positive for the PD-L1 marker). The second patient in the study began 300mg/day oral mifepristone at age 68. Her stage IV lung cancer had progressed despite 4 cycles of carboplatin, permetrexed, and bevacizumab, 6 cycles of carboplatin and docetaxel, and 6 cycles of erlotinib. Finally she progressed and treatment was stopped after 11 cycles of nivolumab (PD-L1 marker present). After 1 year of oral mifepristone there have been no new metastatic lesions. She is ECOG 1 (related to chronic obstructive lung disease). Her cancer is stable with slight reduction in some metastatic lesions. More importantly she states she feels better than at any time since her initial diagnosis. The mechanism of action of mifepristone is hypothesized to be related to suppressing a key immunosuppressive protein that seems to be required for rapidly growing cells (e.g., possibly cancer stem cells), to proliferate known as the progesterone induced blocking factor (PIBF). This protein stablizes perforin granules in natural killer cells, thus obviating their mechanism for cytotoxicity. Mifepristone has been shown to suppress the intracytoplasmic immunosuppressive isoform in cancer cell line studies. Mifepristone can also diminish T-cell cytotoxicity. Progesterone receptor modulators may provide a new treatment option for advanced non-small cell lung cancer, even those positive for the PD-L1 marker that progresses despite treatment with chemotherapy and check-point inhibitors. Because intracytoplasmic PIBF is present in only mesenchymal, embryonic, trophoblast, or cancer cells suppressing this protein does not engender any health risks - oral mifepristone is well tolerated.

Citation Format: Jerome H. Check, Diane Check, Trina Poretta. Mifepristone extends both length and quality of life in a patient with advanced non-small cell lung cancer that progressed despite chemotherapy and check-point inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4715.