Clare L. Scott

Olaparib Maintenance Therapy in Platinum-Sensitive Relapsed Ovarian Cancer

BACKGROUND Olaparib (AZD2281) is an oral poly(adenosine diphosphate [ADP]-ribose) polymerase inhibitor that has shown antitumor activity in patients with high-grade serous ovarian cancer with or without BRCA1 or BRCA2 germline mutations. METHODS We conducted a randomized, double-blind, placebo-controlled, phase 2 study to evaluate maintenance treatment with olaparib in patients with platinum-sensitive, relapsed, high-grade serous ovarian cancer who had received two or more platinum-based regimens and had had a partial or complete response to their most recent platinum-based regimen. Patients were randomly assigned to receive olaparib, at a dose of 400 mg twice daily, or placebo. The primary end point was progression-free survival according to the Response Evaluation Criteria in Solid Tumors guidelines. RESULTS Of 265 patients who underwent randomization, 136 were assigned to the olaparib group and 129 to the placebo group. Progression-free survival was significantly longer with olaparib than with placebo (median, 8.4 months vs. 4.8 months from randomization on completion of chemotherapy; hazard ratio for progression or death, 0.35; 95% confidence interval [CI], 0.25 to 0.49; P<0.001). Subgroup analyses of progression-free survival showed that, regardless of subgroup, patients in the olaparib group had a lower risk of progression. Adverse events more commonly reported in the olaparib group than in the placebo group (by more than 10% of patients) were nausea (68% vs. 35%), fatigue (49% vs. 38%), vomiting (32% vs. 14%), and anemia (17% vs. 5%); the majority of adverse events were grade 1 or 2. An interim analysis of overall survival (38% maturity, meaning that 38% of the patients had died) showed no significant difference between groups (hazard ratio with olaparib, 0.94; 95% CI, 0.63 to 1.39; P=0.75). CONCLUSIONS Olaparib as maintenance treatment significantly improved progression-free survival among patients with platinum-sensitive, relapsed, high-grade serous ovarian cancer. Interim analysis showed no overall survival benefit. The toxicity profile of olaparib in this population was consistent with that in previous studies. (Funded by AstraZeneca; ClinicalTrials.gov number, NCT00753545.).

SOCS1 Is a Critical Inhibitor of Interferon γ Signaling and Prevents the Potentially Fatal Neonatal Actions of this Cytokine

Mice lacking suppressor of cytokine signaling-1 (SOCS1) develop a complex fatal neonatal disease. In this study, SOCS1-/- mice were shown to exhibit excessive responses typical of those induced by interferon gamma (IFNgamma), were hyperresponsive to viral infection, and yielded macrophages with an enhanced IFNgamma-dependent capacity to kill L. major parasites. The complex disease in SOCS1-/- mice was prevented by administration of anti-IFNgamma antibodies and did not occur in SOCS1-/- mice also lacking the IFNgamma gene. Although IFNgamma is essential for resistance to a variety of infections, the potential toxic action of IFNgamma, particularly in neonatal mice, appears to require regulation. Our data indicate that SOCS1 is a key modulator of IFNgamma action, allowing the protective effects of this cytokine to occur without the risk of associated pathological responses.

Olaparib maintenance therapy in patients with platinum-sensitive relapsed serous ovarian cancer: a preplanned retrospective analysis of outcomes by BRCA status in a randomised phase 2 trial

BACKGROUND Maintenance monotherapy with the PARP inhibitor olaparib significantly prolonged progression-free survival (PFS) versus placebo in patients with platinum-sensitive recurrent serous ovarian cancer. We aimed to explore the hypothesis that olaparib is most likely to benefit patients with a BRCA mutation. METHODS We present data from the second interim analysis of overall survival and a retrospective, preplanned analysis of data by BRCA mutation status from our randomised, double-blind, phase 2 study that assessed maintenance treatment with olaparib 400 mg twice daily (capsules) versus placebo in patients with platinum-sensitive recurrent serous ovarian cancer who had received two or more platinum-based regimens and who had a partial or complete response to their most recent platinum-based regimen. Randomisation was by an interactive voice response system, stratified by time to progression on penultimate platinum-based regimen, response to the most recent platinum-based regimen before randomisation, and ethnic descent. The primary endpoint was PFS, analysed for the overall population and by BRCA status. This study is registered with ClinicalTrials.gov, number NCT00753545. FINDINGS Between Aug 28, 2008, and Feb 9, 2010, 136 patients were assigned to olaparib and 129 to placebo. BRCA status was known for 131 (96%) patients in the olaparib group versus 123 (95%) in the placebo group, of whom 74 (56%) versus 62 (50%) had a deleterious or suspected deleterious germline or tumour BRCA mutation. Of patients with a BRCA mutation, median PFS was significantly longer in the olaparib group than in the placebo group (11·2 months [95% CI 8·3-not calculable] vs 4·3 months [3·0-5·4]; HR 0·18 [0·10-0·31]; p<0·0001); similar findings were noted for patients with wild-type BRCA, although the difference between groups was lower (7·4 months [5·5-10·3] vs 5·5 months [3·7-5·6]; HR 0·54 [0·34-0·85]; p=0·0075). At the second interim analysis of overall survival (58% maturity), overall survival did not significantly differ between the groups (HR 0·88 [95% CI 0·64-1·21]; p=0·44); similar findings were noted for patients with mutated BRCA (HR 0·73 [0·45-1·17]; p=0·19) and wild-type BRCA (HR 0·99 [0·63-1·55]; p=0·96). The most common grade 3 or worse adverse events in the olaparib group were fatigue (in ten [7%] patients in the olaparib group vs four [3%] in the placebo group) and anaemia (seven [5%] vs one [<1%]). Serious adverse events were reported in 25 (18%) patients who received olaparib and 11 (9%) who received placebo. Tolerability was similar in patients with mutated BRCA and the overall population. INTERPRETATION These results support the hypothesis that patients with platinum-sensitive recurrent serous ovarian cancer with a BRCA mutation have the greatest likelihood of benefiting from olaparib treatment. FUNDING AstraZeneca.

Analysis of the apoptotic and therapeutic activities of histone deacetylase inhibitors by using a mouse model of B cell lymphoma.

Histone deacetylase inhibitors (HDACi) can elicit a range of biological responses that affect tumor growth and survival, including inhibition of cell cycle progression, induction of tumor cell-selective apoptosis, suppression of angiogenesis, and modulation of immune responses, and show promising activity against hematological malignancies in clinical trials. Using the Eμ-myc model of B cell lymphoma, we screened tumors with defined genetic alterations in apoptotic pathways for therapeutic responsiveness to the HDACi vorinostat. We demonstrated a direct correlation between induction of tumor cell apoptosis in vivo and therapeutic efficacy. Vorinostat did not require p53 activity or a functional death receptor pathway to kill Eμ-myc lymphomas and mediate a therapeutic response but depended on activation of the intrinsic apoptotic pathway with the proapoptotic BH3-only proteins Bid and Bim playing an important role. Our studies provide important information regarding the mechanisms of action of HDACi that have broad implications regarding stratification of patients receiving HDACi therapy alone or in combination with other anticancer agents.

Rucaparib in relapsed, platinum-sensitive high-grade ovarian carcinoma (ARIEL2 Part 1): an international, multicentre, open-label, phase 2 trial

BACKGROUND Poly(ADP-ribose) polymerase (PARP) inhibitors have activity in ovarian carcinomas with homologous recombination deficiency. Along with BRCA1 and BRCA2 (BRCA) mutations genomic loss of heterozygosity (LOH) might also represent homologous recombination deficiency. In ARIEL2, we assessed the ability of tumour genomic LOH, quantified with a next-generation sequencing assay, to predict response to rucaparib, an oral PARP inhibitor. METHODS ARIEL2 is an international, multicentre, two-part, phase 2, open-label study done at 49 hospitals and cancer centres in Australia, Canada, France, Spain, the UK, and the USA. In ARIEL2 Part 1, patients with recurrent, platinum-sensitive, high-grade ovarian carcinoma were classified into one of three predefined homologous recombination deficiency subgroups on the basis of tumour mutational analysis: BRCA mutant (deleterious germline or somatic), BRCA wild-type and LOH high (LOH high group), or BRCA wild-type and LOH low (LOH low group). We prespecified a cutoff of 14% or more genomic LOH for LOH high. Patients began treatment with oral rucaparib at 600 mg twice per day for continuous 28 day cycles until disease progression or any other reason for discontinuation. The primary endpoint was progression-free survival. All patients treated with at least one dose of rucaparib were included in the safety analyses and all treated patients who were classified were included in the primary endpoint analysis. This trial is registered with ClinicalTrials.gov, number NCT01891344. Enrolment into ARIEL2 Part 1 is complete, although an extension (Part 2) is ongoing. FINDINGS 256 patients were screened and 206 were enrolled between Oct 30, 2013, and Dec 19, 2014. At the data cutoff date (Jan 18, 2016), 204 patients had received rucaparib, with 28 patients remaining in the study. 192 patients could be classified into one of the three predefined homologous recombination deficiency subgroups: BRCA mutant (n=40), LOH high (n=82), or LOH low (n=70). Tumours from 12 patients were established as BRCA wild-type, but could not be classified for LOH, because of insufficient neoplastic nuclei in the sample. The median duration of treatment for the 204 patients was 5·7 months (IQR 2·8-10·1). 24 patients in the BRCA mutant subgroup, 56 patients in the LOH high subgroup, and 59 patients in the LOH low subgroup had disease progression or died. Median progression-free survival after rucaparib treatment was 12·8 months (95% CI 9·0-14·7) in the BRCA mutant subgroup, 5·7 months (5·3-7·6) in the LOH high subgroup, and 5·2 months (3·6-5·5) in the LOH low subgroup. Progression-free survival was significantly longer in the BRCA mutant (hazard ratio 0·27, 95% CI 0·16-0·44, p<0·0001) and LOH high (0·62, 0·42-0·90, p=0·011) subgroups compared with the LOH low subgroup. The most common grade 3 or worse treatment-emergent adverse events were anaemia or decreased haemoglobin (45 [22%] patients), and elevations in alanine aminotransferase or aspartate aminotransferase (25 [12%]). Common serious adverse events included small intestinal obstruction (10 [5%] of 204 patients), malignant neoplasm progression (10 [5%]), and anaemia (nine [4%]). Three patients died during the study (two because of disease progression and one because of sepsis and disease progression). No treatment-related deaths occurred. INTERPRETATION In patients with BRCA mutant or BRCA wild-type and LOH high platinum-sensitive ovarian carcinomas treated with rucaparib, progression-free survival was longer than in patients with BRCA wild-type LOH low carcinomas. Our results suggest that assessment of tumour LOH can be used to identify patients with BRCA wild-type platinum-sensitive ovarian cancers who might benefit from rucaparib. These results extend the potential usefulness of PARP inhibitors in the treatment setting beyond BRCA mutant tumours. FUNDING Clovis Oncology, US Department of Defense Ovarian Cancer Research Program, Stand Up To Cancer-Ovarian Cancer Research Fund Alliance-National Ovarian Cancer Coalition Dream Team Translational Research Grant, and V Foundation Translational Award.

Treatment of B-RAF mutant human tumor cells with a MEK inhibitor requires Bim and is enhanced by a BH3 mimetic

B-RAF is frequently mutated in solid tumors, resulting in activation of the MEK/ERK signaling pathway and ultimately tumor cell growth and survival. MEK inhibition in these cells results in cell cycle arrest and cytostasis. Here, we have shown that MEK inhibition also triggers limited apoptosis of human tumor cell lines with B-RAF mutations and that this effect was dependent on upregulation and dephosphorylation of the proapoptotic, Bcl-2 homology 3-only (BH3-only) Bcl-2 family member Bim. However, upregulation of Bim was insufficient for extensive apoptosis and was countered by overexpression of Bcl-2. To overcome apoptotic resistance, we treated the B-RAF mutant cells both with MEK inhibitors and with the BH3 mimetic ABT-737, resulting in profound synergism and extensive tumor cell death. This treatment was successful because of both efficient antagonism of the prosurvival Bcl-2 family member Mcl-1 by Bim and inhibition of Bcl-2 and Bcl-x(L) by ABT-737. Critically, addition of ABT-737 converted the predominantly cytostatic effect of MEK inhibition to a cytotoxic effect, causing long-term tumor regression in mice xenografted with human tumor cell lines. Thus, the therapeutic efficacy of MEK inhibition requires concurrent unleashing of apoptosis by a BH3 mimetic and represents a potent combination treatment for tumors harboring B-RAF mutations.

Unleashing the power of inhibitors of oncogenic kinases through BH3 mimetics

Therapeutic targeting of tumours on the basis of molecular analysis is a new paradigm for cancer treatment but has yet to fulfil expectations. For many solid tumours, targeted therapeutics, such as inhibitors of oncogenic kinase pathways, elicit predominantly disease-stabilizing, cytostatic responses, rather than tumour regression. Combining oncogenic kinase inhibitors with direct activators of the apoptosis machinery, such as the BH3 mimetic ABT-737, may unlock potent anti-tumour potential to produce durable clinical responses with less collateral damage.

Poly (ADP-Ribose) Polymerase Inhibitors: Recent Advances and Future Development

Poly (ADP-ribose) polymerase (PARP) inhibitors have shown promising activity in epithelial ovarian cancers, especially relapsed platinum-sensitive high-grade serous disease. Consistent with preclinical studies, ovarian cancers and a number of other solid tumor types occurring in patients with deleterious germline mutations in BRCA1 or BRCA2 seem to be particularly sensitive. However, it is also becoming clear that germline BRCA1/2 mutations are neither necessary nor sufficient for patients to derive benefit from PARP inhibitors. We provide an update on PARP inhibitor clinical development, describe recent advances in our understanding of PARP inhibitor mechanism of action, and discuss current issues in the development of these agents.

p53 Efficiently Suppresses Tumor Development in the Complete Absence of Its Cell-Cycle Inhibitory and Proapoptotic Effectors p21, Puma, and Noxa

Activation of apoptosis through transcriptional induction of Puma and Noxa has long been considered to constitute the critical (if not sole) process by which p53 suppresses tumor development, although G1/S boundary cell-cycle arrest via induction of the CDK inhibitor p21 has also been thought to contribute. Recent analyses of mice bearing mutations that impair p53-mediated induction of select target genes have indicated that activation of apoptosis and G1/S cell-cycle arrest may, in fact, be dispensable for p53-mediated tumor suppression. However, the expression of Puma, Noxa, and p21 was not abrogated in these mutants, only reduced; therefore, the possibility that the reduced levels of these critical effectors of p53-mediated apoptosis and G1/S-cell-cycle arrest sufficed to prevent tumorigenesis could not be excluded. To resolve this important issue, we have generated mice deficient for p21, Puma, and Noxa (p21-/-puma-/-noxa-/- mice). Cells from these mice were deficient in their ability to undergo p53-mediated apoptosis, G1/S cell-cycle arrest, and senescence. Nonetheless, these animals remained tumor free until at least 500 days, in contrast to p53-deficient mice, which had all succumbed to lymphoma or sarcoma by 250 days. Interestingly, DNA lesions induced by γ-irradiation persisted longer in p53-deficient cells compared to wild-type or p21-/-puma-/-noxa-/- cells, and the former failed to transcriptionally activate several p53 target genes implicated in DNA repair. These results demonstrate beyond a doubt that the induction of apoptosis, cell-cycle arrest, and possibly senescence is dispensable for p53-mediated suppression of spontaneous tumor development and indicate that coordination of genomic stability and possibly other processes, such as metabolic adaptation, may instead be critical.

Analysis of cancer risk and BRCA1 and BRCA2 mutation prevalence in the kConFab familial breast cancer resource.

IntroductionThe Kathleen Cuningham Foundation Consortium for Research into Familial Breast Cancer (kConFab) is a multidisciplinary, collaborative framework for the investigation of familial breast cancer. Based in Australia, the primary aim of kConFab is to facilitate high-quality research by amassing a large and comprehensive resource of epidemiological and clinical data with biospecimens from individuals at high risk of breast and/or ovarian cancer, and from their close relatives.MethodsEpidemiological, family history and lifestyle data, as well as biospecimens, are collected from multiple-case breast cancer families ascertained through family cancer clinics in Australia and New Zealand. We used the Tyrer-Cuzick algorithms to assess the prospective risk of breast cancer in women in the kConFab cohort who were unaffected with breast cancer at the time of enrolment in the study.ResultsOf kConFabs first 822 families, 518 families had multiple cases of female breast cancer alone, 239 had cases of female breast and ovarian cancer, 37 had cases of female and male breast cancer, and 14 had both ovarian cancer as well as male and female breast cancer. Data are currently held for 11,422 people and germline DNAs for 7,389. Among the 812 families with at least one germline sample collected, the mean number of germline DNA samples collected per family is nine. Of the 747 families that have undergone some form of mutation screening, 229 (31%) carry a pathogenic or splice-site mutation in BRCA1 or BRCA2. Germline DNAs and data are stored from 773 proven carriers of BRCA1 or BRCA1 mutations. kConFabs fresh tissue bank includes 253 specimens of breast or ovarian tissue – both normal and malignant – including 126 from carriers of BRCA1 or BRCA2 mutations.ConclusionThese kConFab resources are available to researchers anywhere in the world, who may apply to kConFab for biospecimens and data for use in ethically approved, peer-reviewed projects. A high calculated risk from the Tyrer-Cuzick algorithms correlated closely with the subsequent occurrence of breast cancer in BRCA1 and BRCA2 mutation positive families, but this was less evident in families in which no pathogenic BRCA1 or BRCA2 mutation has been detected.