SummaryResearchers worldwide with information about the Kirsten ras (Ki-ras) tumour genotype and outcome of patients with colorectal cancer were invited to provide that data in a schematized format for inclusion in a collaborative database called RASCAL (The Kirsten ras incolorectal-cancer collaborative group). Our results from 2721 such patients have been presented previously and for the first time in any common cancer, showed conclusively that different gene mutations have different impacts on outcome, even when the mutations occur at the same site on the genome. To explore the effect of Ki-ras mutations at different stages of colorectal cancer, more patients were recruited to the database, which was reanalysed when information on 4268 patients from 42 centres in 21 countries had been entered. After predetermined exclusion criteria were applied, data on 3439 patients were entered into a multivariate analysis. This found that of the 12 possible mutations on codons 12 and 13 of Kirsten ras, only one mutation on codon 12, glycine to valine, found in 8.6% of all patients, had a statistically significant impact on failure-free survival (P = 0.004, HR 1.3) and overall survival (P = 0.008, HR 1.29). This mutation appeared to have a greater impact on outcome in Dukes' C cancers (failure-free survival, P = 0.008, HR 1.5; overall survival P = 0.02, HR 1.45) than in Dukes' B tumours (failure-free survival, P = 0.46, HR 1.12; overall survival P = 0.36, HR 1.15). Ki-ras mutations may occur early in the development of pre-cancerous adenomas in the colon and rectum. However, this collaborative study suggests that not only is the presence of a codon 12 glycine to valine mutation important for cancer progression but also that it may predispose to more aggressive biological behaviour in patients with advanced colorectal cancer. © 2001 Cancer Research Campaign http://www.bjcancer.comIt is widely accepted that mutations in the Kirsten ras (Ki-ras) gene in patients with colorectal cancer develop early in the progression from adenoma to carcinoma. Our first collaborative study including 2721 patients, clarified that Ki-ras mutations are not only 692
BackgroundThere is an urgent need to identify biomarkers to guide personalized therapy in castration-resistant prostate cancer (CRPC). We aimed to clinically qualify androgen receptor (AR) gene status measurement in plasma DNA using multiplex droplet digital PCR (ddPCR) in pre- and post-chemotherapy CRPC.MethodsWe optimized ddPCR assays for AR copy number and mutations and retrospectively analyzed plasma DNA from patients recruited to one of the three biomarker protocols with prospectively collected clinical data. We evaluated associations between plasma AR and overall survival (OS) and progression-free survival (PFS) in 73 chemotherapy-naïve and 98 post-docetaxel CRPC patients treated with enzalutamide or abiraterone (Primary cohort) and 94 chemotherapy-naïve patients treated with enzalutamide (Secondary cohort; PREMIERE trial).ResultsIn the primary cohort, AR gain was observed in 10 (14%) chemotherapy-naïve and 33 (34%) post-docetaxel patients and associated with worse OS [hazard ratio (HR), 3.98; 95% CI 1.74–9.10; P < 0.001 and HR 3.81; 95% CI 2.28–6.37; P < 0.001, respectively], PFS (HR 2.18; 95% CI 1.08–4.39; P = 0.03, and HR 1.95; 95% CI 1.23–3.11; P = 0.01, respectively) and rate of PSA decline ≥50% [odds ratio (OR), 4.7; 95% CI 1.17–19.17; P = 0.035 and OR, 5.0; 95% CI 1.70–14.91; P = 0.003, respectively]. AR mutations [2105T>A (p.L702H) and 2632A>G (p.T878A)] were observed in eight (11%) post-docetaxel but no chemotherapy-naïve abiraterone-treated patients and were also associated with worse OS (HR 3.26; 95% CI 1.47–not reached; P = 0.004). There was no interaction between AR and docetaxel status (P = 0.83 for OS, P = 0.99 for PFS). In the PREMIERE trial, 11 patients (12%) with AR gain had worse PSA-PFS (sPFS) (HR 4.33; 95% CI 1.94–9.68; P < 0.001), radiographic-PFS (rPFS) (HR 8.06; 95% CI 3.26–19.93; P < 0.001) and OS (HR 11.08; 95% CI 2.16–56.95; P = 0.004). Plasma AR was an independent predictor of outcome on multivariable analyses in both cohorts.ConclusionPlasma AR status assessment using ddPCR identifies CRPC with worse outcome to enzalutamide or abiraterone. Prospective evaluation of treatment decisions based on plasma AR is now required.Clinical Trial numberNCT02288936 (PREMIERE trial).
PI3K-Akt-mTOR and androgen receptor (AR) signaling are commonly aberrantly activated in metastatic castration-resistant prostate cancer (mCRPC), with PTEN loss associating with poor prognosis. We therefore conducted a phase Ib/II study of the combination of ipatasertib, an Akt inhibitor, with the CYP17 inhibitor abiraterone in patients with mCRPC. Patients were randomized 1:1:1 to ipatasertib 400 mg, ipatasertib 200 mg, or placebo, with abiraterone 1,000 mg orally. Coprimary efficacy endpoints were radiographic progression-free survival (rPFS) in the intent-to-treat population and in patients with PTEN-loss tumors. rPFS was prolonged in the ipatasertib cohort versus placebo, with similar trends in overall survival and time-to-PSA progression. A larger rPFS prolongation for the combination was demonstrated in PTEN-loss tumors versus those without. The combination was well tolerated, with no treatment-related deaths. In mCRPC, combined blockade with abiraterone and ipatasertib showed superior antitumor activity to abiraterone alone, especially in patients with PTEN-loss tumors.
Purpose Cabazitaxel 25 mg/m (C25) significantly improved overall survival (OS) versus mitoxantrone ( P < .001) in postdocetaxel patients with metastatic castration-resistant prostate cancer (mCRPC) in the phase III TROPIC study. The phase III PROSELICA study ( ClinicalTrials.gov identifier: NCT01308580) assessed the noninferiority of cabazitaxel 20 mg/m (C20) versus C25 in postdocetaxel patients with mCRPC. Methods Patients were stratified by Eastern Cooperative Oncology Group performance status, measurability of disease per Response Evaluation Criteria in Solid Tumors (RECIST), and region, and randomly assigned to receive C20 or C25. To claim noninferiority of C20 (maintenance of ≥ 50% of the OS benefit of C25 v mitoxantrone in TROPIC) with 95% confidence level, the upper boundary of the CI of the hazard ratio (HR) for C20 versus C25 could not exceed 1.214 under a one-sided 98.89% CI after interim analyses. Secondary end points included progression-free survival, prostate-specific antigen (PSA), tumor and pain responses and progression, health-related quality of life, and safety. Results Overall, 1,200 patients were randomly assigned (C20, n = 598; C25, n = 602). Baseline characteristics were similar in both arms. Median OS was 13.4 months for C20 and 14.5 months for C25 (HR, 1.024). The upper boundary of the HR CI was 1.184 (less than the 1.214 noninferiority margin). Significant differences were observed in favor of C25 for PSA response (C20, 29.5%; C25, 42.9%; nominal P < .001) and time to PSA progression (median: C20, 5.7 months; C25, 6.8 months; HR for C20 v C25, 1.195; 95% CI, 1.025 to 1.393). Health-related quality of life did not differ between cohorts. Rates of grade 3 or 4 treatment-emergent adverse events were 39.7% for C20 and 54.5% for C25. Conclusion The efficacy of cabazitaxel in postdocetaxel patients with mCRPC was confirmed. The noninferiority end point was met; C20 maintained ≥ 50% of the OS benefit of C25 versus mitoxantrone in TROPIC. Secondary efficacy end points favored C25. Fewer adverse events were observed with C20.
Molecular characterization of radical prostatectomy specimens after systemic therapy may identify a gene expression profile for resistance to therapy. This study assessed tumor cells from patients with prostate cancer participating in a phase II neoadjuvant docetaxel and androgen deprivation trial to identify mediators of resistance. Transcriptional level of 93 genes from a docetaxel-resistant prostate cancer cell lines microarray study was analyzed by TaqMan low-density arrays in tumors from patients with high-risk localized prostate cancer (36 surgically treated, 28 with neoadjuvant docetaxel þ androgen deprivation). Gene expression was compared between groups and correlated with clinical outcome. VIM, AR and RELA were validated by immunohistochemistry. CD44 and ZEB1 expression was tested by immunofluorescence in cells and tumor samples. Parental and docetaxel-resistant castration-resistant prostate cancer cell lines were tested for epithelial-to-mesenchymal transition (EMT) markers before and after docetaxel exposure. Reversion of EMT phenotype was investigated as a docetaxel resistance reversion strategy. Expression of 63 (67.7%) genes differed between groups (P < 0.05), including genes related to androgen receptor, NF-kB transcription factor, and EMT. Increased expression of EMT markers correlated with radiologic relapse. Docetaxel-resistant cells had increased EMT and stem-like cell markers expression. ZEB1 siRNA transfection reverted docetaxel resistance and reduced CD44 expression in DU-145R and PC-3R. Before docetaxel exposure, a selected CD44 þ subpopulation of PC-3 cells exhibited EMT phenotype and intrinsic docetaxel resistance; ZEB1/CD44 þ subpopulations were found in tumor cell lines and primary tumors; this correlated with aggressive clinical behavior. This study identifies genes potentially related to chemotherapy resistance and supports evidence of the EMT role in docetaxel resistance and adverse clinical behavior in early prostate cancer. Mol Cancer Ther; 13(5); 1270-84. Ó2014 AACR.
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