Raquel Perez Lopez

PTEN Protein Loss and Clinical Outcome from Castration-resistant Prostate Cancer Treated with Abiraterone Acetate

Background Loss of the tumor suppressor phosphatase and tensin homolog (PTEN) occurs frequently in prostate cancers. Preclinical evidence suggests that activation of PI3K/AKT signaling through loss of PTEN can result in resistance to hormonal treatment in prostate cancer. Objective To explore the antitumor activity of abiraterone acetate (abiraterone) in castration-resistant prostate cancer (CRPC) patients with and without loss of PTEN protein expression. Design, setting, and participants We retrospectively identified patients who had received abiraterone and had hormone-sensitive prostate cancer (HSPC) and/or CRPC tissue available for PTEN immunohistochemical analysis. Outcome measurements and statistical analysis The primary end point was overall survival from initiation of abiraterone treatment. Relationship with outcome was analyzed using multivariate Cox regression and log-rank analyses. Results and limitations A total of 144 patients were identified who had received abiraterone post-docetaxel and had available tumor tissue. Overall, loss of PTEN expression was observed in 40% of patients. Matched HSPC and CRPC tumor biopsies were available for 41 patients. PTEN status in CRPC correlated with HSPC in 86% of cases. Loss of PTEN expression was associated with shorter median overall survival (14 vs 21 mo; hazard ratio [HR]: 1.75; 95% confidence interval [CI], 1.19–2.55; p = 0.004) and shorter median duration of abiraterone treatment (24 vs 28 wk; HR: 1.6; 95% CI, 1.12–2.28; p = 0.009). PTEN protein loss, high lactate dehydrogenase, and the presence of visceral metastases were identified as independent prognostic factors in multivariate analysis. Conclusions Our results indicate that loss of PTEN expression was associated with worse survival and shorter time on abiraterone treatment. Further studies in larger and prospective cohorts are warranted. Patient summary PTEN is a protein often lost in prostate cancer cells. In this study we evaluated if prostate cancers that lack this protein respond differently to treatment with abiraterone acetate. We demonstrated that the survival of patients with loss of PTEN is shorter than patients with normal PTEN expression.

Abstract PR14: Phase I trial of first-in-class ataxia telangiectasia-mutated and Rad3-related (ATR) inhibitor VX-970 as monotherapy (mono) or in combination with carboplatin (CP) in advanced cancer patients (pts) with preliminary evidence of target modulation and antitumor activity

Background: ATR mediates the homologous recombination DNA repair pathway and cellular response to replication stress. VX-970 is a potent and selective inhibitor of ATR (Ki Methods: Pts with advanced solid tumors enrolled in 2 sequential parts. Part A: pts received IV VX-970 mono weekly in single-pt cohorts, with 3+3 cohorts initiated if grade (G) ≥2 VX-970-related adverse events (AEs) were observed. Part B: pts received CP on day 1 and VX-970 on days 2 and 9 of a 21-day cycle in a 3+3 dose-escalation design. Paired VX-970 tumor biopsies were obtained in selected CP treated pts pre- and post-VX-970, and pS345 Chk1 levels assessed by IHC. Results: 25 pts were treated; M/F 10/15; median age 67 yr (range 49-76 yr); ECOG PS 0/1: 11/14. In Part A, 11 pts (colorectal [CRC; n = 2]; mesothelioma [n = 2]; other [n = 7]; median prior lines of therapy = 3) received VX-970 at 60 mg/m2 (n = 1), 120 mg/m2 (n = 2), 240 mg/m2 (n = 1) and 480 mg/m2 (n = 7). In Part B, 14 pts (CRC [n = 6]; ovarian [n = 2]; other [n = 6]; median prior lines of therapy = 3) received VX-970 240 mg/m2 + CP AUC5 (n = 3; dose level 1 [DL1]), VX-970 120 mg/m2 + CP AUC5 (n = 3; DL2), VX-970 120 mg/m2 + CP AUC4 (n = 3; DL3) and VX-970 90 mg/m2 + CP AUC5 (n = 5; DL4). In Part A, no dose-limiting toxicities (DLT) or drug-related G3-4 AEs were seen. In Part B, 2 pts had DLT: G4 neutropenia and fever (n = 1; DL1) and G3 hypersensitivity (n = 1; DL2). Non-DLT G3-4 AEs were neutropenia (n = 4; DL1-2) and thrombocytopenia (n = 1; DL2) requiring dose delays. No G3-4 AEs were seen at DL3-4. RP2D cohort expansion is ongoing at DL4. VX-970 displayed linear AUC and Cmax at all DLs; median half-life was 16h with no accumulation. Based on preclinical models, efficacious exposures were achieved. When combined with CP, DL1 and DL2 showed similar VX-970 exposure, suggesting no apparent drug interactions. Decreased Chk1 phosphorylation was seen in 2/2 paired tumor biopsies (74% at DL4; 94% at DL2). An advanced CRC pt (serosal disease and abdominal lymphadenopathy; 3 prior lines of chemotherapy) with complete ATM loss by IHC achieved RECIST complete response to VX-970 mono at 60 mg/m2 and remains on trial at 59+ wks. RECIST stable disease (SD) was seen with VX-970 mono in 4 pts (median duration of SD = 11 wks [11-17.4 wks]) and VX-970 + CP in 7 pts, who were still ongoing (duration of SD = 5+ to 20+ wks), including several pts who had progressed on prior platinum therapy. Conclusion: VX-970 is well tolerated as monotherapy and in combination with CP, with preliminary evidence of target modulation and antitumor activity. VX-970 will be further explored in early phase II studies; in multiple tumor types, including triple-negative breast cancer and non-small cell lung cancer; and in patients with DDR aberrations. Citation Format: Timothy A. Yap, Maria J. de Miguel Luken, Brent O9Carrigan, Desam Roda, Dionysis Papadatos-Pastos, David Lorente, Nina Tunariu, Raquel Perez Lopez, Sasha Gayle, Ruth Riisnaes, Ines Figueiredo, Susana Miranda, Suzanne Carreira, Fang Yang, Sharon Karan, Marina Penney, John Pollard, L. Rhoda Molife, Udai Banerji, Mohammed Asmal, Scott Z. Fields, Johann S. de Bono. Phase I trial of first-in-class ataxia telangiectasia-mutated and Rad3-related (ATR) inhibitor VX-970 as monotherapy (mono) or in combination with carboplatin (CP) in advanced cancer patients (pts) with preliminary evidence of target modulation and antitumor activity. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr PR14.

Effect on Overall Survival of Locoregional Treatment in a Cohort of De Novo Metastatic Prostate Cancer Patients: A Single Institution Retrospective Analysis From the Royal Marsden Hospital

Micro‐Abstract We retrospectively evaluated the effect of locoregional treatment (LRT) on overall survival (OS) in 300 metastatic at diagnosis (M1) prostate cancer patients. LRT was associated in univariate and multivariate analysis with longer OS, which remained significant for radiotherapy but not for transurethral prostatectomy. These data support further prospective evaluation of the benefit of local control in this patient population. Background: The optimal management of the primary tumor in metastatic at diagnosis (M1) prostate cancer (PCa) patients is not yet established. We retrospectively evaluated the effect of locoregional treatment (LRT) on overall survival (OS) hypothesizing that this could improve outcome through better local disease control and the induction of an antitumor immune response (abscopal effect). Patients and Methods: M1 at diagnosis PCa patients referred to the Prostate Targeted Therapy Group at the Royal Marsden between June 2003 and December 2013 were identified. LRT was defined as either surgery, radiotherapy (RT) or transurethral prostatectomy (TURP) administered to the primary tumor at any time point from diagnosis to death. Kaplan–Meier analyses generated OS data. The association between LRT and OS was evaluated in univariate (UV) and multivariate (MV) Cox regression models. Results: Overall 300 patients were identified; 192 patients (64%) experienced local symptoms at some point during their disease course; 72 patients received LRT (56.9% TURP, 52.7% RT). None of the patients were treated with prostatectomy. LRT was more frequently performed in patients with low volume disease (35.4% vs. 16.2%; P < .001), lower prostate‐specific antigen (PSA) level at diagnosis (median PSA: 75 vs. 184 ng/mL; P = .005) and local symptoms (34.2% vs. 4.8%; P < .001). LRT was associated in UV and MV analysis with longer OS (62.1 vs. 55.8 months; hazard ratio [HR], 0.74; P = .044), which remained significant for RT (69.4 vs. 55.1 months; HR, 0.54; P = .002) but not for TURP. RT was associated with better OS independent of disease volume at diagnosis. Conclusion: These data support the conduct of randomized phase III trials to evaluate the benefit of local control in patients with M1 disease at diagnosis.

Predicting positive bone marrow biopsies (BMBs) in patients (PTS) with advanced prostate cancer (APC).

180 Background: Advanced prostate cancer (APC) is a molecularly heterogeneous disease, with evidence of clonal evolution that could be responsible for resistance to treatment. About 90% of patients (pts) with APC have bone metastases. The acquisition of a bone marrow biopsies (BMBs) is a safe and feasible technique for obtaining tissue, with a low rate of complications. We hypothesized that pre-biopsy clinical variables may increase the success rate of BMBs in APC. Methods: Standard BMBs of the iliac crest were performed in APC pts between October 2011 and June 2013. All pts signed ethics approved consent. In the control cohort (n=10) BMBs were collected in pts with normal CT and bone scan appearance. Minimum, maximum, and mean Hounsfield Units (HU) of the iliac crest on pre-biopsy CTs were determined. Clinical and laboratory variables were collected from the electronic record system. Biopsies were defined as containing 50 or more or 1 to 50 malignant cells or none (negative). Univariate analysis was perf...