Olaparib (AZD2281, Ku-0059436)

Olaparib (4-(3-4-fluorophenyl) methyl-1(2H)-one), as known as AZD2281 or KU0059436, is a novel, selective and potent inhibitor of both poly adenosine diphosphate-ribose polymeras-1 (PARP-1) and poly adenosine diphosphate-ribose polymeras-2 (PARP-2).  Having been successfully used in the treatment of tumors harboring BRCA mutations, olaparib strongly inhibits the growth of BRCA2-deficient mouse mannary tumor cell lines demonstrating cytotoxicity. In previous researches treating non-small cell lung carcinoma (NSCLC), olaparib increased the radiation sensitivity of NSCLC cells, grown as xenografts in nude mice, following radiation and increased vascular perfusion in Calu-6 tumors established in a dorsal window chamber (DWC) model.

Reference

Joana M. Senra, Brian A. Telfer, Kim E. Cherry, Cian M. McCrudden, David G. Hirst, Mark J. O’Connor, Stephen R. Wedge, and Ian J. Stratford. Inhibition of poly(ADP-ribose) polymerase-1 by olaparib (AZD2281) increases the radiosensitivity of a lung tumor xenograft. Mol Cancer Ther. 2011; 10(10): 1949-1958

Bastiaan Evers, Rinske Drost, Eva Schut, Michiel Bruin, Eline vab der Burg, Patrick W.B. Derksen, Henne Holstege, Xiaoling Liu, Ellen van Drunen, H. Berna Beverloo, Graeme C. M. Smith, Niall M. B. Martin, Alan Lau, Mark J. O’Connor, and Jos Jonkers. Selective inhibition of BRCA2-deficient mammary tumor cell growth by AZD2281 and Cisplatin. Clin Cancer Res 2008; 14:3916-3925

The PARP inhibitor AZD2281 (Olaparib) induces autophagy/mitophagy in BRCA1 and BRCA2 mutant breast cancer cells.[Pubmed:25975349]

Int J Oncol. 2015 Jul;47(1):262-8.

PARP inhibitors are considered promising anticancer agents and currently being tested in clinical trials in hereditary breast cancer patients harboring mutations in BRCA1 and BRCA2 genes. In this study, we investigated the antiproliferative effects and mechanism of PARP inhibitors ABT-888 (Veliparib), BSI-201 (Iniparib) and AZD228 (Olaparib) in breast cancer cell lines with BRCA1 or BRCA2 mutations and 9 different BRCA wild-type cell lines with BRCA1 allelic loss. We found that AZD2281 was the most potent in the PARP inhibitors and induces significant growth inhibition (~95%) in BRCA1 mutant (HCC1937, MDA-MB-436, and SUM-149PT) and BRCA2 mutant (HCC1428) cell lines. AZD2281 treatment also resulted in growth inhibition ranging from 20 to 50% in cells with BRCA1 allelic loss, including ER(+), HER2/Neu(+) and triple-negative breast cancer (TNBC) cells, but showed no effect in cells without with type BRCA without allelic loss. Knocking down of BRCA1 or BRCA2 in TNBC cells with BRCA1 allelic loss by RNA interference significantly enhanced AZD2281-induced growth inhibition and induced significant autophagy that was associated with mitophagy in cells with BRCA mutations. Inhibition of autophagy by gene knockdown significantly diminished AZD2281-induced mitophagy and apoptosis, indicating that autophagic process mediates some of the downstream effects of PARP inhibitors. In conclusion, our data provide the first evidence of PARP inhibitor AZD2281 autophagy and mitophagy in breast cancer cell lines with BRCA mutations or BRCA-allelic loss. In addition, our results indicate that the patients with BRCA1 allelic loss may also benefit from PARP inhibitor therapy if BRCA is further inhibited.

APR-246 (PRIMA-1(MET)) strongly synergizes with AZD2281 (olaparib) induced PARP inhibition to induce apoptosis in non-small cell lung cancer cell lines.[Pubmed:26975633]

Cancer Lett. 2016 Jun 1;375(2):313-322.

APR-246 (PRIMA-1(Met)) is able to bind mutant p53 and restore its normal conformation and function. The compound has also been shown to increase intracellular ROS levels. Importantly, the poly-[ADP-ribose] polymerase-1 (PARP-1) enzyme plays an important role in the repair of ROS-induced DNA damage. We hypothesize that by blocking this repair with the PARP-inhibitor AZD2281 (olaparib), DNA damage would accumulate in the cell leading to massive apoptosis. We observed that APR-246 synergistically enhanced the cytotoxic response of olaparib in TP53 mutant non-small cell lung cancer cell lines, resulting in a strong apoptotic response. In the presence of wild type p53 a G2/M cell cycle block was predominantly observed. NOXA expression levels were significantly increased in a TP53 mutant background, and remained unchanged in the wild type cell line. The combined treatment of APR-246 and olaparib induced cell death that was associated with increased ROS production, accumulation of DNA damage and translocation of p53 to the mitochondria. Out data suggest a promising targeted combination strategy in which the response to olaparib is synergistically enhanced by the addition of APR-246, especially in a TP53 mutant background.

The use of Olaparib (AZD2281) potentiates SN-38 cytotoxicity in colon cancer cells by indirect inhibition of Rad51-mediated repair of DNA double-strand breaks.[Pubmed:24577941]

Mol Cancer Ther. 2014 May;13(5):1170-80.

Potent application of topoisomerase I inhibitor plus PARP inhibitor has been suggested to be an effective strategy for cancer therapy. Reportedly, mismatch repair (MMR)-deficient colon cancer cells are sensitive to topoisomerase I inhibitor, presumably due to microsatellite instability (MSI) of the MRE11 locus. We examined the synergy of SN-38, an active metabolite of irinotecan, in combination with the PARP inhibitor olaparib in colon cancer cells showing different MMR status, such as MSI or microsatellite stable (MSS) phenotype. Treatment with SN-38 and olaparib in combination almost halved the IC50 of SN-38 for a broad spectrum of colon cancer cells independent of the MMR status. Furthermore, olaparib potentiated S-phase-specific double-strand DNA breaks (DSB) induced by SN-38, which is followed by Rad51 recruitment. siRNA-mediated knockdown of Rad51, but not Mre11 or Rad50, increased the sensitivity to olaparib and/or SN-38 treatment in colon cancer cells. In vivo study using mouse xenograft demonstrated that olaparib was effective to potentiate the antitumor effect of irinotecan. In conclusion, olaparib shows a synergistic effect in colon cancer cells in combination with SN-38 or irinotecan, potentiated by the Rad51-mediated HR pathway, irrespective of the Mre11-mediated failure of the MRN complex. These results may contribute to future clinical trials using PARP inhibitor plus topoisomerase I inhibitor in combination. Furthermore, the synergistic effect comprising topoisomerase I-mediated DNA breakage-reunion reaction, PARP and Rad51-mediated HR pathway suggests the triple synthetic lethal pathways contribute to this event and are applicable as a potential target for future chemotherapy.

Combination of AZD2281 (Olaparib) and GX15-070 (Obatoclax) results in synergistic antitumor activities in preclinical models of pancreatic cancer.[Pubmed:24534203]

Cancer Lett. 2014 Jun 28;348(1-2):20-8.

In this study, we explored the antitumor activities of the PARP inhibitor AZD2281 (Olaparib) and the pan-Bcl-2 inhibitor GX15-070 (Obatoclax) in six pancreatic cancer cell lines. While both agents were able to cause growth arrest and limited apoptosis, the combination of the two was able to synergistically cause growth arrest and non-apoptotic cell death. Furthermore, in an in vivo xenograft model, the combination caused substantially increased tumor necrosis compared to either treatment alone. Our results support further investigation of the combination of Bcl-2 and PARP inhibitors for the treatment of pancreatic cancer.

Olaparib (AZD2281; KU0059436) is a potent and orally active PARP inhibitor with IC50s of 5 and 1 nM for PARP1 and PARP2, respectively. Olaparib is an autophagy and mitophagy activator.

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