Citations

Abstract Purpose: To determine the dose limiting toxicities (DLT), maximum tolerated dose (MTD), and recommended phase II dose (RP2D) of veliparib in combination with weekly topotecan in patients with solid tumors. Correlative studies were included to assess the impact of topotecan and veliparib on poly(ADP-ribose) levels in peripheral blood mononuclear cells, serum pharmacokinetics of both agents, and potential association of germline repair gene mutations with outcome. Experimental Design: Eligible patients had metastatic nonhematologic malignancies with measurable disease. Using a 3 + 3 design, patients were treated with veliparib orally twice daily on days 1–3, 8–10, and 15–17 and topotecan intravenously on days 2, 9, and 16 every 28 days. Tumor responses were assessed by RECIST. Results: Of 58 patients enrolled, 51 were evaluable for the primary endpoint. The MTD and RP2D was veliparib 300 mg twice daily on days 1–3, 8–10, and 15–17 along with topotecan 3 mg/m2 on days 2, 9, and 16 of a 28-day cycle. DLTs were grade 4 neutropenia lasting >5 days. The median number of cycles was 2 (1–26). The objective response rate was 10%, with 1 complete and 4 partial responses. Twenty-two patients (42%) had stable disease ranging from 4 to 26 cycles. Patients with germline BRCA1, BRCA2, or RAD51D mutations remained on study longer than those without homologous recombination repair (HRR) gene mutations (median 4 vs. 2 cycles). Conclusions: Weekly topotecan in combination with veliparib has a manageable safety profile and appears to warrant further investigation.

Abstract Background: PARP inhibitors (PARPis) are active in cancers with homologous recombination (HR) defects. Preclinical studies have shown that secondary mutations or alterations in gene expression (e.g., downregulation of 53BP1, Ku70, Ku80 or DNA-PKcs) restore HR and confer PARPi resistance. In addition, low PARP1 expression can diminish PARP trapping and cause PARPi resistance. ARIEL2 Part 1 is a phase 2 study of the PARPi rucaparib in platinum sensitive, relapsed high grade serous or endometrioid ovarian cancer (OC). Pretreatment OC biopsies were previously assayed for HR gene mutations and loss of heterozygosity (LOH), a genomic scar that reflects HR deficiency. Two tumor groups (BRCA wildtype [wt]/LOH high and BRCA1 or BRCA2 mutant) have objective response rates of 29.3% and 80%, respectively, as well as progression free survival (PFS) of 5.7 and 12.8 months, respectively, on rucaparib (E. Swisher et al., Lancet Oncol., in press). Common AEs included nausea (80%), asthenia/fatigue (78%), constipation (46%), and vomiting (44%). The present studies tested the hypotheses that i) lower PARP1 expression and/or ii) lower expression of NHEJ components 53BP1, DNA-PKcs, Ku80, Ku70, or LIG4, may correlate with diminished response rate as well as PFS in pts treated with rucaparib on ARIEL2. Methods: Immunohistochemical assays were developed for 53BP1, DNA-PKcs, Ku80, Ku70, LIG4, and PARP1 and validated in formalin fixed, paraffin embedded cell lines differing in analyte expression. Available pretreatment OC biopsies from ARIEL2 Part 1 were stained and scored for % of tumor nuclei that were negative (0), weak (1+), moderate (2+) or strong (3+). Modified H-scores were correlated with clinical characteristics and outcome measures. Results: Pretreatment biopsies from 62-68 pts were successfully stained for each repair protein. Across the samples, PARP1 H-scores varied from 0 to 300 (median 160). Focusing on the BRCA wt/LOH high group (n = 38), there was no significant difference in PFS of pts with low (<100), intermediate (100-200) or high (>200) PARP1 H-score (p = 0.57). Expression of DNA-PKcs, Ku70, Ku80, and LIG4 was generally lower (median H-scores 20-60) and did not individually correlate with response or PFS. In contrast, there was a trend toward improved PFS in BRCA wt/LOH high OC pts expressing intermediate or high 53BP1 (H-score ≥ 100, n = 10) compared to pts with low 53BP1 (H-score <100, n = 25), with median PFS 20.7 vs. 5.5 months (p = 0.073), respectively. Staining of additional pretreatment biopsies is planned. Conclusions: In the BRCA wt/LOH high group, pretreatment PARP1 expression does not correlate with rucaparib response. In contrast, BRCA wt/LOH high OC pts with low 53BP1 have a trend toward shorter PFS with rucaparib, suggesting that 53BP1 downregulation might correlate with clinical PARPi resistance in BRCA wt/LOH high OC. Citation Format: Andrea E. Wahner Hendrickson, Kevin K. Lin, Daniel W. Visscher, Rachel M. Hurley, Mitch Raponi, Thomas C. Harding, Linda M. Murphy, Jill M. Wagner, Heidi Giordano, Iain McNeish, Elizabeth M. Swisher, Scott Kaufmann. DNA repair protein expression and response of homologous recombination deficient ovarian cancer to the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib in the ARIEL2 Part 1 study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4676. doi:10.1158/1538-7445.AM2017-4676

Abstract Poly(ADP-ribose) polymerase (PARP) inhibitors have shown promising single-agent activity in ovarian cancers with BRCA1 and BRCA2 mutations (C. Scott, JCO 33:1397, 2015). Ongoing studies are testing the efficacy of PARP inhibitors in ovarian cancers with other genetic or epigenetic alterations that impair the homologous recombination (HR) pathway of DNA repair. It is less clear whether PARP inhibitor clinical activity can be enhanced in HR deficient cancers or even extended to HR proficient ovarian cancers through judicious combinations. Our preclinical studies have demonstrated that PARP inhibitors enhance the cytotoxic effects of selected therapeutic agents through a variety of mechanisms: By trapping PARP at sites of DNA damage, PARP inhibitors enhance the cytotoxicity of topotecan (A. Patel, J. Biol. Chem. 287: 4198, 2012).By inhibiting base excision repair, PARP inhibitors enhance the cytotoxicity of floxuridine (A. Huehls, Cancer Res. 71: 4944, 2011), an agent previously shown to have clinical activity in ovarian cancer. Building on the first of these observations, we conducted a phase 1 clinical trial of topotecan weekly x 3 in combination with veliparib (NCT01012817). Using a standard 3+3 design, patients were treated with veliparib PO twice daily on days 1-3, 8-10 and 15-17 and topotecan IV on days 2, 9 and 16 every 28 days. The dose-limiting toxicity was neutropenia. The MTD was veliparib 300 mg PO twice daily and topotecan 3 mg/m2/dose. Among 52 evaluable patients, objective responses (1 CR, 3 PRs) and stable disease (22 patients, 6 lasting ≥ 8 cycles) were observed. While there was no clear correlation between germline BRCA1 or BRCA2 mutations and clinical benefit, a patient with a germline RAD51D mutation had stable disease for 14 cycles. A phase 2 cohort in platinum-resistant ovarian cancer has just opened. Building on the second set of preclinical observations, we are also conducting a phase 1 trial of veliparib and IP floxuridine in patients with recurrent ovarian cancer confined to the peritoneal cavity (NCT01749397). Using a rolling 6 design, patients are treated with veliparib PO twice daily on days 1-10 and floxuridine IP on days 3-5 every 21 days. The trial is currently enrolling at dose level 5 (veliparib 300 mg PO twice daily on days 1-10 and floxuridine 3 gm/dose IP on days 3-5). Grade 3 toxicities in any cycle have included nausea (1), fatigue (1) and neutropenia (3). Among 20 evaluable patients, treatment duration has ranged from 2-33 cycles. These studies, which build on two different aspects of PARP1 function, illustrate two different approaches to potentially enhancing the activity of PARP inhibitors in relapsed ovarian cancer. These studies were funded in part by NIH grants P50 CA136393, R01 CA190423, and UM1 CA186686 as well as SU2C-AACR DT16-15. Citation Format: Scott H. Kaufmann, Andrea E. Wahner Hendrickson, Maria I Harrell, Michael E. Menefee, Edward J. Tanner, David G, Mutch, Elizabeth M. Swisher, and Larry M. Karnitz. PARP INHIBITOR COMBINATIONS FOR THE TREATMENT OF OVARIAN CANCER [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr IS04.

Abstract Resistance is one the main reason for overall decrease in survival of cancer patient treated with cisplatin in different types of cancer. Cisplatin kills cancer cells by various mechanisms, but mainly through formation of inter- and intra stand crosslinks of DNA. Different types of translesion polymerase including Polymerase kappa (POLK) are involved in repair of DNA lesions. We observed high expression levels of POLK in cisplatin resistant bladder and ovarian cancer cells compared to parental cells. Due to its low proof-reading activity POLK can incorporate 8-oxo-dGTP into DNA. The MTH1 protein (Nudix hydrolase- NUDT1) sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Recently we have generated MTH1 inhibitors that damage the DNA and induce cancer specific cell death through incorporation of more oxidized dNTPs. We found cisplatin resistant bladder cancer cells (NTUB1/P) were more sensitive to MTH1 inhibitors in comparison to parental NTUB1 cells. As POLK is involved in incorporation of 8-oxo-dGTP into DNA, we hypothesized that high expression levels of POLK in cisplatin resistant cells make them more sensitive to MTH1 inhibitors as more 8-oxo-dGTP would be incorporated into DNA, resulting in more DNA damage and cell death in comparison to parental cells. Indeed, we observes higher induction of cleaved-PARP, γH2AX, cleaved-Caspase 3 and more annexin v positive cells in cisplatin resistant NTUB1/P cells in comparison to parental NTUB1 cells upon treatment with MTH1 inhibitors. MTH1 inhibitor also significantly delays the NTUB1/P xenograft tumor growth in comparison to vehicle treatment in immunosuppressive mice. Knocking down POLK in cisplatin resistant NTUB1/P cells by siRNA resulted in decreased incorporation of 8-oxo-dGTP and sensitivity to MTH1 inhibitors compared to non target control cells. Overexpression of POLK in NTUB1 and NTUB1/P cells results in further sensitization to MTH1 inhibitors. In conclusion elevated levels of POLK in cisplatin resistance cells determines increased sensitivity towards MTH1 inhibitors. Thus MTH1 inhibitors can be a potential promising therapy for the treatment of cisplatin resistant tumors in patients. Citation Format: Kumar Sanjiv, Helge Gad, Sean Rudd, Rachel Hurley, Patric Herr, José Manuel Calderón Montaño, Oliver Mortusewicz, Tobias Koolmeister, Sylvain Jaques, Estefanía Burgos Morón, Andreas Hoglund, Te-Chang Lee, Martin Scobie, Scott Kaufmann, John Weroha, Ulrika Warpman Berglund, Andrea Wahner Hendrickson, Thomas Helleday. Polymerase kappa determines the sensitivity of MTH1 inhibitors to cisplatin-resistant cell. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1260.

AbstractAnti‐cytotoxic T lymphocyte‐associated antigen‐4 (CTLA‐4) and anti‐programmed cell death‐1 (PD‐1) inhibitors have been shown to significantly improve survival in patients with metastatic cutaneous melanoma. However, there was some heterogeneity as well as some variation in the degree of benefit across studies. We reviewed randomized trials and performed a meta‐analysis to determine the efficacy and safety of immune checkpoint inhibitors in comparison with conventional regimens. Eligible studies were limited to randomized controlled trials comparing anti‐CTLA‐4 or anti‐PD‐1 inhibitors to chemotherapy or vaccination treatment in adult patients with unresectable cutaneous metastatic melanoma. Progression‐free survival (PFS) rate at 6 months was 28.5% versus 17.7% (RR: 0.84, 95% CI: 0.76–0.93), overall survival (OS) rate at 1 year was 51.2% versus 38.8% (RR: 0.72, 95% CI: 0.59–0.88), and overall response rate (ORR) at 6 months was 29.6% versus 17.7% (RR: 0.85, 95% CI: 0.76–0.95) favoring immune check point inhibitors over chemotherapies or vaccination. Immune check point inhibitors were associated with more frequent immune‐related adverse events at 13.7% versus 2.4% of treated patients (RR: 6.74, 95% CI: 4.65–9.75). Subgroup analyses demonstrated significant PFS (RR: 0.92 vs. 0.74, P < 0.00001) and ORR (RR: 0.95 vs. 0.76, P = 0.0004) improvement with anti‐PD‐1 treatment compared to anti‐CTLA‐4 when each of them was compared to control treatments. Collectively, these results demonstrate that immune checkpoint inhibitors have superior outcomes compared to conventional chemotherapies or vaccination, and support the results of recent randomized trials that showed superior outcomes with anti‐PD‐1 agents over ipilimumab in unresectable metastatic cutaneous melanoma patients.

Key Points Agents that inhibit both complexes containing the mammalian target of rapamycin are particularly toxic to acute lymphocytic leukemia cells. This killing reflects engagement of a 4EBP1/c-MYC/PUMA axis downstream of mTORC1 and an NF-κB/EGR1/BIM axis downstream of mTORC2.

Abstract Replication stress and DNA damage activate the ATR-Chk1 checkpoint signaling pathway that licenses repair and cell survival processes. In this study, we examined the respective roles of the ATR and Chk1 kinases in ovarian cancer cells using genetic and pharmacologic inhibitors in combination with cisplatin, topotecan, gemcitabine, and the PARP inhibitor veliparib (ABT-888), four agents with clinical activity in ovarian cancer. RNA interference (RNAi)–mediated depletion or inhibition of ATR sensitized ovarian cancer cells to all four agents. In contrast, while cisplatin, topotecan, and gemcitabine each activated Chk1, RNAi-mediated depletion or inhibition of this kinase in cells sensitized them only to gemcitabine. Unexpectedly, we found that neither the ATR kinase inhibitor VE-821 nor the Chk1 inhibitor MK-8776 blocked ATR-mediated Chk1 phosphorylation or autophosphorylation, two commonly used readouts for inhibition of the ATR-Chk1 pathway. Instead, their ability to sensitize cells correlated with enhanced CDC25A levels. In addition, we also found that VE-821 could further sensitize BRCA1-depleted cells to cisplatin, topotecan, and veliparib beyond the potent sensitization already caused by their deficiency in homologous recombination. Taken together, our results established that ATR and Chk1 inhibitors differentially sensitize ovarian cancer cells to commonly used chemotherapy agents and that Chk1 phosphorylation status may not offer a reliable marker for inhibition of the ATR-Chk1 pathway. A key implication of our work is the clinical rationale it provides to evaluate ATR inhibitors in combination with PARP inhibitors in BRCA1/2-deficient cells. Cancer Res; 73(12); 3683–91. ©2013 AACR.

Abstract The mammalian target of rapamycin (mTOR) plays crucial roles in proliferative and antiapoptotic signaling in lymphoid malignancies. Rapamycin analogs, which are allosteric mTOR complex 1 (mTORC1) inhibitors, are active in mantle cell lymphoma and other lymphoid neoplasms, but responses are usually partial and short-lived. In the present study we compared the effects of rapamycin with the dual mTORC1/mTORC2 inhibitor OSI-027 in cell lines and clinical samples representing divers lymphoid malignancies. In contrast to rapamycin, OSI-027 markedly diminished proliferation and induced apoptosis in a variety of lymphoid cell lines and clinical samples, including specimens of B-cell acute lymphocytic leukemia (ALL), mantle cell lymphoma, marginal zone lymphoma and Sezary syndrome. Additional analysis demonstrated that OSI-027–induced apoptosis depended on transcriptional activation of the PUMA and BIM genes. Overexpression of Bcl-2, which neutralizes Puma and Bim, or loss of procaspase 9 diminished OSI-027–induced apoptosis in vitro. Moreover, OSI-027 inhibited phosphorylation of mTORC1 and mTORC2 substrates, up-regulated Puma, and induced regressions in Jeko xenografts. Collectively, these results not only identify a pathway that is critical for the cytotoxicity of dual mTORC1/mTORC2 inhibitors, but also suggest that simultaneously targeting mTORC1 and mTORC2 might be an effective anti-lymphoma strategy in vivo.