David Olmos

Selective Inhibition of CYP17 With Abiraterone Acetate Is Highly Active in the Treatment of Castration-Resistant Prostate Cancer

PURPOSE It has been postulated that castration-resistant prostate cancer (CRPC) commonly remains hormone dependent. Abiraterone acetate is a potent, selective, and orally available inhibitor of CYP17, the key enzyme in androgen and estrogen biosynthesis. PATIENTS AND METHODS This was a phase I/II study of abiraterone acetate in castrate, chemotherapy-naive CRPC patients (n = 54) with phase II expansion at 1,000 mg (n = 42) using a two-stage design to reject the null hypothesis if more than seven patients had a prostate-specific antigen (PSA) decline of > or = 50% (null hypothesis = 0.1; alternative hypothesis = 0.3; alpha = .05; beta = .14). Computed tomography scans every 12 weeks and circulating tumor cell (CTC) enumeration were performed. Prospective reversal of resistance at progression by adding dexamethasone 0.5 mg/d to suppress adrenocorticotropic hormone and upstream steroids was pursued. RESULTS A decline in PSA of > or = 50% was observed in 28 (67%) of 42 phase II patients, and declines of > or = 90% were observed in eight (19%) of 42 patients. Independent radiologic evaluation reported partial responses (Response Evaluation Criteria in Solid Tumors) in nine (37.5%) of 24 phase II patients with measurable disease. Decreases in CTC counts were also documented. The median time to PSA progression (TTPP) on abiraterone acetate alone for all phase II patients was 225 days (95% CI, 162 to 287 days). Exploratory analyses were performed on all 54 phase I/II patients; the addition of dexamethasone at disease progression reversed resistance in 33% of patients regardless of prior treatment with dexamethasone, and pretreatment serum androgen and estradiol levels were associated with a probability of > or = 50% PSA decline and TTPP on abiraterone acetate and dexamethasone. CONCLUSION CYP17 blockade by abiraterone acetate results in declines in PSA and CTC counts and radiologic responses, confirming that CRPC commonly remains hormone driven.

Significant and Sustained Antitumor Activity in Post-Docetaxel, Castration-Resistant Prostate Cancer With the CYP17 Inhibitor Abiraterone Acetate

PURPOSE The principal objective of this trial was to evaluate the antitumor activity of abiraterone acetate, an oral, specific, irreversible inhibitor of CYP17 in docetaxel-treated patients with castration-resistant prostate cancer (CRPC). PATIENTS AND METHODS In this multicenter, two-stage, phase II study, abiraterone acetate 1,000 mg was administered once daily continuously. The primary end point was achievement of a prostate-specific antigen (PSA) decline of > or = 50% in at least seven of 35 patients. Per an attained phase II design, more than 35 patients could be enrolled if the primary end point was met. Secondary objectives included: PSA declines of > or = 30% and > or = 90%; rate of RECIST (Response Evaluation Criteria in Solid Tumors) responses and duration on study; time to PSA progression; safety and tolerability; and circulating tumor cell (CTC) enumeration. RESULTS Docetaxel-treated patients with CRPC (N = 47) were enrolled. PSA declines of > or = 30%, > or = 50% and > or = 90% were seen in 68% (32 of 47), 51% (24 of 47), and 15% (seven of 47) of patients, respectively. Partial responses (by RECIST) were reported in eight (27%) of 30 patients with measurable disease. Median time to PSA progression was 169 days (95% CI, 113 to 281 days). The median number of weeks on study was 24, and 12 (25.5%) of 47 patients remained on study > or = 48 weeks. CTCs were enumerated in 34 patients; 27 (79%) of 34 patients had at least five CTCs at baseline. Eleven (41%) of 27 patients had a decline from at least five to less than 5 CTCs, and 18 (67%) of 27 had a > or = 30% decline in CTCs after starting treatment with abiraterone acetate. Abiraterone acetate was well tolerated. CONCLUSION Abiraterone acetate has significant antitumor activity in post-docetaxel patients with CRPC. Randomized, phase III trials of abiraterone acetate are underway to define the future role of this agent.

First-in-Man Clinical Trial of the Oral Pan-AKT Inhibitor MK-2206 in Patients With Advanced Solid Tumors

PURPOSE AKT signaling is frequently deregulated in human cancers. MK-2206 is a potent, oral allosteric inhibitor of all AKT isoforms with antitumor activity in preclinical models. A phase I study of MK-2206 was conducted to investigate its safety, maximum-tolerated dose (MTD), pharmacokinetics (PKs), pharmacodynamics (PDs), and preliminary antitumor efficacy. PATIENTS AND METHODS Patients with advanced solid tumors received MK-2206 on alternate days. Paired tumor biopsies were mandated at the MTD for biomarker studies. PD studies incorporated tumor and hair follicle analyses, and putative predictive biomarker studies included tumor somatic mutation analyses and immunohistochemistry for phosphatase and tensin homolog (PTEN) loss. RESULTS Thirty-three patients received MK-2206 at 30, 60, 75, or 90 mg on alternate days. Dose-limiting toxicities included skin rash and stomatitis, establishing the MTD at 60 mg. Drug-related toxicities included skin rash (51.5%), nausea (36.4%), pruritus (24.2%), hyperglycemia (21.2%), and diarrhea (21.2%). PKs (area under the concentration-time curve from 0 to 48 hours and maximum measured plasma concentration) were dose proportional. Phosphorylated serine 473 AKT declined in all tumor biopsies assessed (P = .015), and phosphorylated threonine 246 proline-rich AKT substrate 40 was suppressed in hair follicles at 6 hours (P = .008), on days 7 (P = .028) and 15 (P = .025) with MK-2206; reversible hyperglycemia and increases in insulin c-peptide were also observed, confirming target modulation. A patient with pancreatic adenocarcinoma (PTEN loss; KRAS G12D mutation) treated at 60 mg on alternate days experienced a decrease of approximately 60% in cancer antigen 19-9 levels and 23% shrinkage in tumor measurements. Two patients with pancreatic neuroendocrine tumors had minor tumor responses. CONCLUSION MK-2206 was well tolerated, with evidence of AKT signaling blockade. Rational combination trials are ongoing to maximize clinical benefit with this therapeutic strategy.

Safety, pharmacokinetics, and preliminary activity of the anti-IGF-1R antibody figitumumab (CP-751,871) in patients with sarcoma and Ewing's sarcoma: a phase 1 expansion cohort study

BACKGROUND Figitumumab is a fully human IgG2 monoclonal antibody targeting the insulin-like growth-factor-1 receptor (IGF-1R). Preclinical data suggest a dependence on insulin-like growth-factor signalling for sarcoma subtypes, including Ewings sarcoma, and early reports show antitumour activity of IGF-1R-targeting drugs in these diseases. METHODS Between January, 2006, and August, 2008, patients with refractory, advanced sarcomas received figitumumab (20 mg/kg) in two single-stage expansion cohorts within a solid-tumour phase 1 trial. The first cohort (n=15) included patients with multiple sarcoma subtypes, age 18 years or older, and the second cohort (n=14) consisted of patients with refractory Ewings sarcoma, age 9 years or older. The primary endpoint was to assess the safety and tolerability of figitumumab. Secondary endpoints included pharmacokinetic profiling and preliminary antitumour activity (best response by Response Evaluation Criteria in Solid Tumours [RECIST]) in evaluable patients who received at least one dose of medication. This study is registered with ClinicalTrials.gov, number NCT00474760. FINDINGS 29 patients, 16 of whom had Ewings sarcoma, were enrolled and received a total of 177 cycles of treatment (median 2, mean 6.1, range 1-24). Grade 3 deep venous thrombosis, grade 3 back pain, and grade 3 vomiting were each noted once in individual patients; one patient had grade 3 increases in aspartate aminotransferase and gammaglutamyltransferase concentrations. This patient also had grade 4 increases in alanine aminotransferase concentrations. The only other grade 4 adverse event was raised concentrations of uric acid, noted in one patient. Pharmacokinetics were comparable between patients with sarcoma and those with other solid tumours. 28 patients were assessed for response; two patients, both with Ewings sarcoma, had objective responses (one complete response and one partial response) and eight patients had disease stabilisation (six with Ewings sarcoma, one with synovial sarcoma, and one with fibrosarcoma) lasting 4 months or longer. INTERPRETATION Figitumumab is well tolerated and has antitumour activity in Ewings sarcoma, warranting further investigation in this disease. FUNDING Pfizer Global Research and Development.

Germline BRCA Mutations Are Associated With Higher Risk of Nodal Involvement, Distant Metastasis, and Poor Survival Outcomes in Prostate Cancer

PURPOSE To analyze the baseline clinicopathologic characteristics of prostate tumors with germline BRCA1 and BRCA2 (BRCA1/2) mutations and the prognostic value of those mutations on prostate cancer (PCa) outcomes. PATIENTS AND METHODS This study analyzed the tumor features and outcomes of 2,019 patients with PCa (18 BRCA1 carriers, 61 BRCA2 carriers, and 1,940 noncarriers). The Kaplan-Meier method and Cox regression analysis were used to evaluate the associations between BRCA1/2 status and other PCa prognostic factors with overall survival (OS), cause-specific OS (CSS), CSS in localized PCa (CSS_M0), metastasis-free survival (MFS), and CSS from metastasis (CSS_M1). RESULTS PCa with germline BRCA1/2 mutations were more frequently associated with Gleason ≥ 8 (P = .00003), T3/T4 stage (P = .003), nodal involvement (P = .00005), and metastases at diagnosis (P = .005) than PCa in noncarriers. CSS was significantly longer in noncarriers than in carriers (15.7 v 8.6 years, multivariable analyses [MVA] P = .015; hazard ratio [HR] = 1.8). For localized PCa, 5-year CSS and MFS were significantly higher in noncarriers (96% v 82%; MVA P = .01; HR = 2.6%; and 93% v 77%; MVA P = .009; HR = 2.7, respectively). Subgroup analyses confirmed the poor outcomes in BRCA2 patients, whereas the role of BRCA1 was not well defined due to the limited size and follow-up in this subgroup. CONCLUSION Our results confirm that BRCA1/2 mutations confer a more aggressive PCa phenotype with a higher probability of nodal involvement and distant metastasis. BRCA mutations are associated with poor survival outcomes and this should be considered for tailoring clinical management of these patients.

Circulating tumour cell (CTC) counts as intermediate end points in castration-resistant prostate cancer (CRPC): a single-centre experience

BACKGROUND The purpose of this study was to evaluate the association of circulating tumour cell (CTC) counts, before and after commencing treatment, with overall survival (OS) in patients with castration-resistant prostate cancer (CRPC). EXPERIMENTAL DESIGN A 7.5 ml of blood was collected before and after treatment in 119 patients with CRPC. CTCs were enumerated using the CellSearchSystem. RESULTS Higher CTC counts associated with baseline characteristics portending aggressive disease. Multivariate analyses indicated that a CTC >or=5 was an independent prognostic factor at all time points evaluated. Patients with baseline CTC >or=5 had shorter OS than those with <5 [median OS 19.5 versus >30 months, hazard ratio (HR) 3.25, P=0.012]; patients with CTC >50 had a poorer OS than those with CTCs 5-50 (median OS 6.3 versus 21.1 months, HR 4.1, P<0.001). Patients whose CTC counts reduced from >or=5 at baseline to <5 following treatment had a better OS compared with those who did not. CTC counts showed a similar, but earlier and independent, ability to time to disease progression to predict OS. CONCLUSION CTC counts predict OS and provide independent prognostic information to time to disease progression; CTC dynamics following therapy need to be evaluated as an intermediate end point of outcome in randomised phase III trials.

Antitumour activity of docetaxel following treatment with the CYP17A1 inhibitor abiraterone: clinical evidence for cross-resistance?

BACKGROUND Abiraterone and docetaxel are both approved treatments for men with metastatic castration-resistant prostate cancer (mCRPC). Abiraterone pre-docetaxel is currently undergoing evaluation in a phase III study. In vitro studies indicate that taxanes may act by disrupting androgen receptor signalling. We hypothesised that prior abiraterone exposure would adversely impact docetaxel efficacy. PATIENTS AND METHODS We retrospectively evaluated activity of docetaxel in mCRPC patients previously treated with abiraterone, using Prostate Cancer Working Group and radiological criteria. RESULTS Of the 54 patients treated with abiraterone, 35 subsequently received docetaxel. Docetaxel resulted in a prostate-specific antigen (PSA) decline of ≥50% in nine patients [26%, 95% confidence interval (CI) 13% to 43%], with a median time to PSA progression of 4.6 months (95% CI 4.2% to 5.9%). PSA declines ≥30% were achieved by 13 patients (37%, 95% CI 22% to 55%). The median overall survival was 12.5 months (95% CI 10.6-19.4). All patients who failed to achieve a PSA fall on abiraterone and were deemed abiraterone-refractory were also docetaxel-refractory (N = 8). In the 24 patients with radiologically evaluable disease, partial responses were reported in four patients (11%), none of whom were abiraterone-refractory. CONCLUSION The activity of docetaxel post-abiraterone appears lower than anticipated and no responses to docetaxel were observed in abiraterone-refractory patients.BACKGROUND Abiraterone and docetaxel are both approved treatments for men with metastatic castration-resistant prostate cancer (mCRPC). Abiraterone pre-docetaxel is currently undergoing evaluation in a phase III study. In vitro studies indicate that taxanes may act by disrupting androgen receptor signalling. We hypothesised that prior abiraterone exposure would adversely impact docetaxel efficacy. PATIENTS AND METHODS We retrospectively evaluated activity of docetaxel in mCRPC patients previously treated with abiraterone, using Prostate Cancer Working Group and radiological criteria. RESULTS Of the 54 patients treated with abiraterone, 35 subsequently received docetaxel. Docetaxel resulted in a prostate-specific antigen (PSA) decline of ≥50% in nine patients [26%, 95% confidence interval (CI) 13% to 43%], with a median time to PSA progression of 4.6 months (95% CI 4.2% to 5.9%). PSA declines ≥30% were achieved by 13 patients (37%, 95% CI 22% to 55%). The median overall survival was 12.5 months (95% CI 10.6-19.4). All patients who failed to achieve a PSA fall on abiraterone and were deemed abiraterone-refractory were also docetaxel-refractory (N = 8). In the 24 patients with radiologically evaluable disease, partial responses were reported in four patients (11%), none of whom were abiraterone-refractory. CONCLUSION The activity of docetaxel post-abiraterone appears lower than anticipated and no responses to docetaxel were observed in abiraterone-refractory patients.

Circulating Tumor Cell Biomarker Panel As an Individual-Level Surrogate for Survival in Metastatic Castration-Resistant Prostate Cancer

PURPOSE Trials in castration-resistant prostate cancer (CRPC) need new clinical end points that are valid surrogates for survival. We evaluated circulating tumor cell (CTC) enumeration as a surrogate outcome measure. PATIENTS AND METHODS Examining CTCs alone and in combination with other biomarkers as a surrogate for overall survival was a secondary objective of COU-AA-301, a multinational, randomized, double-blind phase III trial of abiraterone acetate plus prednisone versus prednisone alone in patients with metastatic CRPC previously treated with docetaxel. The biomarkers were measured at baseline and 4, 8, and 12 weeks, with 12 weeks being the primary measure of interest. The Prentice criteria were applied to test candidate biomarkers as surrogates for overall survival at the individual-patient level. RESULTS A biomarker panel using CTC count and lactate dehydrogenase (LDH) level was shown to satisfy the four Prentice criteria for individual-level surrogacy. Twelve-week surrogate biomarker data were available for 711 patients. The abiraterone acetate plus prednisone and prednisone-alone groups demonstrated a significant survival difference (P = .034); surrogate distribution at 12 weeks differed by treatment (P < .001); the discriminatory power of the surrogate to predict mortality was high (weighted c-index, 0.81); and adding the surrogate to the model eliminated the treatment effect on survival. Overall, 2-year survival of patients with CTCs < 5 (low risk) versus patients with CTCs ≥ 5 cells/7.5 mL of blood and LDH > 250 U/L (high risk) at 12 weeks was 46% and 2%, respectively. CONCLUSION A biomarker panel containing CTC number and LDH level was shown to be a surrogate for survival at the individual-patient level in this trial of abiraterone acetate plus prednisone versus prednisone alone for patients with metastatic CRPC. Additional trials are ongoing to validate the findings.

Risk-Adapted Management for Patients With Clinical Stage I Seminoma: The Second Spanish Germ Cell Cancer Cooperative Group Study

PURPOSE To assess the efficacy of a risk-adapted treatment policy for patients with stage I seminoma by using universally accepted risk criteria. PATIENTS AND METHODS Between 1999 and 2003, 314 patients with clinical stage I seminoma after orchiectomy were prospectively included. One hundred patients (31.8%) presented no risk factors and were managed with surveillance. In contrast, 131 patients (41.7%) had tumors larger than 4 cm, 33 patients (10.5%) had rete testis involvement, and 50 patients (15.9%) had both risk factors. All the latter received two courses of adjuvant carboplatin. RESULTS Chemotherapy was well tolerated, as only 17 patients (7.9%) presented grade 3 to 4 toxicity. Relapses were observed in six patients (6.0%) on surveillance and in seven patients (3.3%) treated with carboplatin (0.8% of tumors larger than 4 cm, 9.1% of those involving the rete testis, and 6.0% of patients with both risk criteria). All were located at the retroperitoneum, except for one at the spermatic cord. Median tumor size was 25 mm (range, 11 to 70 mm), and median time to relapse was 9 months (range, 4 to 28 months). All patients were rendered disease-free with chemotherapy (etoposide plus cisplatin). Median follow-up was 34 months (range, 12 to 72 months). The actuarial 5-year disease-free survival rate was 93.4% for patients on surveillance and 96.2% for patients treated with adjuvant chemotherapy. Overall 5-year survival was 100%. CONCLUSION Adjuvant carboplatin is effective in reducing the relapse rate in patients with stage I seminoma and risk factors. A risk-adapted strategy is safe and feasible and should be considered an alternative to systematic approaches, such as irradiation, chemotherapy, or surveillance.

Phase I trial of a selective c-MET inhibitor ARQ 197 incorporating proof of mechanism pharmacodynamic studies

PURPOSE The hepatocyte growth factor/c-MET axis is implicated in tumor cell proliferation, survival, and angiogenesis. ARQ 197 is an oral, selective, non-adenosine triphosphate competitive c-MET inhibitor. A phase I trial of ARQ 197 was conducted to assess safety, tolerability, and target inhibition, including intratumoral c-MET signaling, apoptosis, and angiogenesis. PATIENTS AND METHODS Patients with solid tumors amenable to pharmacokinetic and pharmacodynamic studies using serial biopsies, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and circulating endothelial cell (CEC) and circulating tumor cell (CTC) enumeration were enrolled. RESULTS Fifty-one patients received ARQ 197 at 100 to 400 mg twice per day. ARQ 197 was well tolerated, with the most common toxicities being grade 1 to 2 fatigue, nausea, and vomiting. Dose-limiting toxicities included grade 3 fatigue (200 mg twice per day; n = 1); grade 3 mucositis, palmar-plantar erythrodysesthesia, and hypokalemia (400 mg twice per day; n = 1); and grade 3 to 4 febrile neutropenia (400 mg twice per day, n = 2; 360 mg twice per day, n = 1). The recommended phase II dose was 360 mg twice per day. ARQ 197 systemic exposure was dose dependent and supported twice per day oral dosing. ARQ 197 decreased phosphorylated c-MET, total c-MET, and phosphorylated focal adhesion kinase and increased terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling (TUNEL) staining in tumor biopsies (n = 15). CECs decreased in 25 (58.1%) of 43 patients, but no significant changes in DCE-MRI parameters were observed after ARQ 197 treatment. Of 15 patients with detectable CTCs, eight (53.3%) had ≥ 30% decline in CTCs after treatment. Stable disease, as defined by Response Evaluation Criteria in Solid Tumors (RECIST), ≥ 4 months was observed in 14 patients, with minor regressions in gastric and Merkel cell cancers. CONCLUSION ARQ 197 safely inhibited intratumoral c-MET signaling. Further clinical evaluation focusing on combination approaches, including an erlotinib combination in non-small-cell lung cancer, is ongoing.