Supplementary Data 1 from Phase II DORA Study of Olaparib with or without Durvalumab as a Chemotherapy-Free Maintenance Strategy in Platinum-Pretreated Advanced Triple-Negative Breast Cancer
Tira J. TanSarah SammonsYoung‐Hyuck ImLilin SheKelly MundyRobert BigelowTiffany A. TrainaCarey K. AndersJoe YeongEzequiel RenzulliSung‐Bae KimRebecca Dent
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<p>Supplement</p>Keywords:
Olaparib
Durvalumab
Triple-negative breast cancer
Abstract Background PARP inhibitors (PARPi) benefit only a fraction of breast cancer patients with BRCA mutations, and their efficacy is even more limited in triple-negative breast cancer (TNBC) due to clinical primary and acquired resistance. Here, we found that the efficacy of the PARPi olaparib in TNBC can be improved by combination with the CDK4/6 inhibitor (CDK4/6i) palbociclib. Methods We screened primary olaparib-sensitive and olaparib-resistant cell lines from existing BRCA mut /TNBC cell lines and generated cells with acquired olaparib resistance by gradually increasing the concentration. The effects of the PARPi olaparib and the CDK4/6i palbociclib on BRCA mut /TNBC cell lines were examined in both sensitive and resistant cells in vitro and in vivo. Pathway and gene alterations were assessed mechanistically and pharmacologically. Results We demonstrated for the first time that the combination of olaparib and palbociclib has synergistic effects against BRCA mut /TNBC both in vitro and in vivo. In olaparib-sensitive MDA-MB-436 cells, the single agent olaparib significantly inhibited cell viability and affected cell growth due to severe DNA damage. In olaparib-resistant HCC1937 and SUM149 cells, single-agent olaparib was ineffective due to potential homologous recombination (HR) repair, and the combination of olaparib and palbociclib greatly inhibited HR during the G2 phase, increased DNA damage and inhibited tumour growth. Inadequate DNA damage caused by olaparib activated the Wnt signalling pathway and upregulated MYC. Further experiments indicated that the overexpression of β-catenin, especially its hyperphosphorylation at the Ser675 site, activated the Wnt signalling pathway and mediated olaparib resistance, which could be strongly inhibited by combined treatment with palbociclib. Conclusions Our data provide a rationale for clinical evaluation of the therapeutic synergy of the PARPi olaparib and CDK4/6i palbociclib in BRCA mut /TNBCs with high Wnt signalling activation and high MYC expression that do not respond to PARPi monotherapy.
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Triple-negative breast cancer
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Meeting abstracts As single agents, durvalumab (MEDI4736), a human IgG1 anti-PD-L1 antibody, and tremelimumab, a human IgG2 anti-CTLA-4 antibody, have shown acceptable safety profiles and antitumor activity. Similar to other anti-PD-L1/anti-PD-1 monotherapies, durvalumab has shown greater objective
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Castration-resistant prostate cancer remains as an incurable disease. Exploiting DNA damage repair defects via inhibition of poly (ADP-ribose) polymerase (PARP) is becoming an attractive therapeutic option. The TOPARP-A clinical trial demonstrated that the PARP inhibitor olaparib may be an effective strategy for treating prostate cancer. However, several unanswered questions regarding the use of olaparib remain: 1) How do we best stratify patients for olaparib treatment? 2) Where do we place olaparib in the treatment sequence paradigm? 3) Is there cross-resistance between olaparib and currently used therapies? Here, we tested putative cross-resistance between current therapies and olaparib in treatment-resistant castration-resistant prostate cancer models. Docetaxel-resistant cells exhibited robust resistance to olaparib which could be attributed to blunted PARP trapping in response to olaparib treatment. Upregulated ABCB1 mediates cross-resistance between taxanes and olaparib, which can be overcome through decreasing ABCB1 expression or inhibiting ABCB1 using elacridar or enzalutamide. We also show that combining olaparib with enzalutamide is more effective in olaparib-sensitive cells than either single agent. Our results demonstrate that cross-resistance between olaparib and other therapies could blunt response to treatment and highlight the need to develop strategies to maximize olaparib efficacy.
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When resection is not an option, platinum-based chemoradiotherapy (CRT) has been the historic standard of care in non-small cell lung cancer (NSCLC). Prognosis remains poor with CRT alone. Durvalumab has shown significant improvement (versus placebo) in progression-free and overall survival in patients with unresectable stage III NSCLC without progression following CRT.This article aims to provide an overview of the efficacy and safety outcomes with durvalumab in patients with stage III NSCLC and identify management strategies for potential adverse events (AEs).A review of published literature and guidelines was performed to evaluate durvalumab clinical outcomes and AE management strategies.Durvalumab has established efficacy in patients with unresectable stage III NSCLC and is now the standard of care following CRT. Nurses need to be trained to recognize potential immune-related AEs in patients treated with immune checkpoint inhibitors.
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Introduction: Immune checkpoint inhibitors, monoclonal antibodies directed against programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1), have broadened treatment options for patients with non-small cell lung cancer (NSCLC). Durvalumab is a selective, high-affinity, human IgG1 monoclonal anti-PD-L1 antibody that blocks interactions of PD-L1 with PD-1 and CD80.Areas covered: We reviewed clinical data supporting the use of durvalumab as a monotherapy and combination therapy for the treatment of locally advanced and advanced NSCLC.Expert commentary: Durvalumab as a monotherapy or combination therapy has shown well-tolerated safety profiles for NSCLC in several trials. Durvalumab monotherapy in advanced NSCLC patients with PD-L1 ≥ 25% as later line (ATLANTIC study) therapy led to clinically meaningful improvements compared to standard of care. Combination therapy comprising durvalumab plus tremelimumab for advanced NSCLC did not show clinical efficacy in three phase III trials. Durvalumab administered after chemoradiotherapy in stage III NSCLC (PACIFIC study) significantly improved progression-free survival and overall survival. This result has led to approval of durvalumab for patients with locally advanced NSCLC as the standard of care. Ongoing trials provide insight into how durvalumab fits into the rapidly evolving therapeutic landscape for locally advanced or advanced NSCLC.
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Olaparib is a PARP inhibitor (PARPi) approved for targeted treatment of ovarian cancer (OC). However, its efficacy is impeded by the inevitable occurrence of resistance. Here, we investigated whether the cytotoxic activity of olaparib could be synergistically enhanced in olaparib-resistant OC cells with BRCA2 reversion mutation by the addition of inhibitors of the ATR/CHK1 pathway. Moreover, we provide insights into alterations in the DNA damage response (DDR) pathway induced by combination treatments. Antitumor activity of olaparib alone or combined with an ATR inhibitor (ATRi, ceralasertib) or CHK1 inhibitor (CHK1i, MK-8776) was evaluated in OC cell lines sensitive (PEO1, PEO4) and resistant (PEO1-OR) to olaparib. Antibody microarrays were used to explore changes in expression of 27 DDR-related proteins. Olaparib in combination with ATR/CHK1 inhibitors synergistically induced a decrease in viability and clonogenic survival and an increase in apoptosis mediated by caspase-3/7 in all OC cells. Combination treatments induced cumulative alterations in expression of DDR-related proteins mediating distinct DNA repair pathways and cell cycle control. In the presence of ATRi and CHK1i, olaparib-induced upregulation of proteins determining cell fate after DNA damage (PARP1, CHK1, c-Abl, Ku70, Ku80, MDM2, and p21) was abrogated in PEO1-OR cells. Overall, the addition of ATRi or CHK1i to olaparib effectively overcomes resistance to PARPi exerting anti-proliferative effect in BRCA2MUT olaparib-resistant OC cells and alters expression of DDR-related proteins. These new molecular insights into cellular response to olaparib combined with ATR/CHK1 inhibitors might help improve targeted therapies for olaparib-resistant OC.
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The PARP inhibitor (PARPi) olaparib is currently the drug of choice for serous ovarian cancer (OC), especially in patients with homologous recombination (HR) repair deficiency associated with deleterious BRCA1/2 mutations. Unfortunately, OC patients who fail to respond to PARPi or relapse after treatment have limited therapeutic options. To elucidate olaparib resistance and enhance the efficacy of olaparib, intracellular factors exploited by OC cells to achieve decreased sensitivity to PARPi were examined. An olaparib-resistant OC cell line, PEO1-OR, was established from BRCA2MUT PEO1 cells. The anticancer activity and action of olaparib combined with inhibitors of the ATR/CHK1 pathway (ceralasertib as ATRi, MK-8776 as CHK1i) in olaparib-sensitive and -resistant OC cell lines were evaluated. Whole-exome sequencing revealed that PEO1-OR cells acquire resistance through subclonal enrichment of BRCA2 secondary mutations that restore functional full-length protein. Moreover, PEO1-OR cells upregulate HR repair-promoting factors (BRCA1, BRCA2, RAD51) and PARP1. Olaparib-inducible activation of the ATR/CHK1 pathway and G2/M arrest is abrogated in olaparib-resistant cells. Drug sensitivity assays revealed that PEO1-OR cells are less sensitive to ATRi and CHK1i agents. Combined treatment is less effective in olaparib-resistant cells considering inhibition of metabolic activity, colony formation, survival, accumulation of DNA double-strand breaks, and chromosomal aberrations. However, synergistic antitumor activity between compounds is achievable in PEO1-OR cells. Collectively, olaparib-resistant cells display co-existing HR repair-related mechanisms that confer resistance to olaparib, which may be effectively utilized to resensitize them to PARPi via combination therapy. Importantly, the addition of ATR/CHK1 pathway inhibitors to olaparib has the potential to overcome acquired resistance to PARPi.
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Abstract Cholangiocarcinoma (CCA) is a highly malignant tumor with resistance to radiotherapy alone. Olaparib, a highly potent poly(ADP‐ribose) polymerase (PARP) inhibitor, has been shown to sensitize many types of tumor to radiotherapy. However, the effect of olaparib, either as monotherapy or as combination therapy with radiotherapy, on CCA is not known, and our study aimed to explore this. To assess radiosensitization in three CCA cell lines (QBC939, HuH28 and TFK‐1), viability and clonogenic assays were conducted. The absorbed radiation doses were 0 Gy, 2 Gy, 4 Gy, and 6 Gy; olaparib concentrations were 0 nmol/L, 1 nmol/L, 10 nmol/L, 100 nmol/L, 1000 nmol/L, 2500 nmol/L, 5000 nmol/L and 10 000 nmol/L. The mechanism of olaparib radiosensitization was explored by Western blotting. Immunofluorescence staining and flow cytometry were conducted to explore DNA damage and apoptosis. The radiosensitivity of CCA cells was enhanced by olaparib, which alone had little effect on the CCA cell lines without BRCA mutations. The degree of radiosensitization increased with increasing doses of olaparib by viability and clonogenic assays in vitro . Olaparib was able to enhance the effect of radiation by inhibiting PARP1, inducing DNA lesions and apoptosis. These findings emphasize the role of olaparib in the radiosensitization of CCA cells.
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Following the practice-changing results observed in several hematological and solid tumors, immunotherapy with immune checkpoint inhibitors (ICIs) has been tested in cholangiocarcinoma (CCA) patients. However, ICI monotherapy has had disappointing results in CCA, and phase I-III clinical trials have assessed whether combinatorial strategies including immunotherapy plus other anticancer agents may have a synergistic activity. The TOPAZ-1 trial has recently highlighted improved survival in CCA patients receiving first-line durvalumab plus gemcitabine-cisplatin compared with gemcitabine plus cisplatin alone, and several guidelines consider adding durvalumab to the reference doublet as standard of care. This article provides an overview of durvalumab pharmacology, safety and efficacy in CCA, highlighting current and future research directions in this setting.Several treatments have been recently tested for cholangiocarcinoma patients. Among these, interesting results have been reported for immunotherapy with durvalumab, and the combination of immunotherapy plus chemotherapy represents a novel and important option in this setting.
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