sirolimus and olaparib

Several 'lines of therapy' that utilize cytotoxic agents and are driven by platinum-free intervals are the current standard of care for patients with recurrent ovarian cancer. For patients with platinum-resistant disease, single agent chemotherapy (pegylated liposomal doxorubicin, topotecan, gemcitabine or weekly paclitaxel) is the standard of care. For patients with platinum-sensitive disease, combination chemotherapy (carboplatin plus paclitaxel, pegylated liposomal doxorubicin or gemcitabine) is the standard of care. In addition, antiangiogenic therapy using bevacizumab is an established option. Future directions could include 'lines of therapy' with biologic agents driven by specific biologic targets. Data from antiangiogenic agents (trebananib, pazopanib and cediranib), antifolate drugs (farletuzumab and vintafolide), poly(ADP-ribose) polymerase inhibitors (olaparib and veliparib), mTOR inhibitors (everolimus and temsirolimus) and immune editing agents (nivolumab) have been summarized in this review.

Topics: Angiogenesis Inhibitors; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antimetabolites, Antineoplastic; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Benzimidazoles; Carboplatin; Carcinoma, Ovarian Epithelial; Deoxycytidine; Doxorubicin; Everolimus; Female; Folic Acid; Gemcitabine; Humans; Indazoles; Neoplasm Recurrence, Local; Neoplasms, Glandular and Epithelial; Nivolumab; Ovarian Neoplasms; Paclitaxel; Phthalazines; Piperazines; Poly(ADP-ribose) Polymerase Inhibitors; Polyethylene Glycols; Pyrimidines; Quinazolines; Recombinant Fusion Proteins; Sirolimus; Sulfonamides; Topotecan; TOR Serine-Threonine Kinases; Vinca Alkaloids

Inhibition of poly(ADP-ribose) polymerase (PARP) is a promising therapeutic strategy for BRCA1 deficient cancers, however, the development of drug resistance limits clinical efficacy. Previously we found that the BRCA1-AKT1 pathway contributes to tumorigenesis and that the AKT1/mTOR is a novel therapeutic target for BRCA1-deficient cancers. Here, we report that phosphorylation of ribosomal protein S6, a mTOR downstream effector, is greatly increased in BRCA1 deficient cells resistant to PARP inhibition. Phosphorylation of S6 is associated with DNA damage and repair signaling during PARP inhibitor treatment. In BRCA1 deficient cells, expression of S6 lacking all five phosphorylatable sites renders the cells sensitive to PARP inhibitor and increases DNA damage signals. In addition, the S6 mutations reduce tumor formation induced by Brca1-deficiency in mice. Inhibition of S6 phosphorylation by rapamycin restores PARP sensitivity to resistant cells. Combined treatment with rapamycin and PARP inhibitor effectively suppresses BRCA1-deficient tumor growth in mice. These results provide evidence for a novel mechanism by which BRCA1 deficient cancers acquire drug resistance and suggest a new therapeutic strategy to circumvent resistance.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Drug Resistance, Neoplasm; Female; Fluorescent Antibody Technique; Gene Knock-In Techniques; Humans; Immunohistochemistry; Mice; Phosphorylation; Phthalazines; Piperazines; Poly(ADP-ribose) Polymerase Inhibitors; Ribosomal Protein S6; Sirolimus; Ubiquitin-Protein Ligases; Xenograft Model Antitumor Assays

Lymphangioleiomyomatosis (LAM) is a female-predominant cystic lung disease that can lead to respiratory failure. LAM cells typically have inactivating tuberous sclerosis complex 2 (TSC2) mutations and mammalian target of rapamycin (mTOR) complex (mTORC) 1 activation. Clinical response to the mTORC1 inhibitors has been limited, prompting a search for additional therapy for LAM. In this study, we investigated the impact of TSC2 on the expression of poly (ADP-ribose) polymerase (PARP)-1 that initiates the DNA repair pathway, and tested the efficacy of PARP1 inhibitors in the survival of TSC2-deficient (TSC2(-)) cells. We analyzed publicly available expression arrays of TSC2(-) cells and validated the findings using real-time RT-PCR, immunoblotting, and immunohistochemistry. We examined the impact of rapamycin and Torin 1 on PARP1 expression. We also tested the effect of PARP1 inhibitors, 8-hydroxy-2-methylquinazoline-4-one and 3,4-dihydro-5[4-(1-piperindinyl)butoxy]-1(2H)-isoquinoline, on the survival of TSC2(-) cells. We identified the up-regulation of PARP1 in TSC2(-) cells relative to cells in which wild-type TSC2 has been reintroduced (TSC2-addback [TSC2(+)] cells). The transcript levels of PARP1 in TSC2(-) cells were not affected by rapamycin. PARP1 levels were increased in TSC2(-) cells, xenograft tumors of rat-derived TSC2(-) cells, renal cystadenomas from Tsc2(+/-) mice, and human LAM nodules. RNA interference of mTOR failed to reduce PARP1 levels. Proliferation and survival of TSC2(-) cells was reduced in response to PARP1 inhibitor treatment, more so than TSC2(+) cells. TSC2(-) cells exhibit higher levels of PARP1 relative to TSC2(+) cells in an mTOR-insensitive manner. PARP1 inhibitors selectively suppress the growth and induce apoptosis of TSC2(-) cells from patients with LAM. Targeting PARP1 may be beneficial in the treatment of LAM and other neoplasm with mTORC1 activation.

Topics: Animals; Antineoplastic Agents; Cell Line; DNA Repair; Drug Resistance, Neoplasm; Female; Gene Expression Regulation, Enzymologic; Humans; Isoquinolines; Lung Neoplasms; Lymphangioleiomyomatosis; Mice, Inbred C57BL; Mice, SCID; Molecular Targeted Therapy; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Quinazolines; Rats; Sirolimus; Tuberous Sclerosis Complex 2 Protein; Tumor Suppressor Proteins; Up-Regulation; Xenograft Model Antitumor Assays