Despite evidence that shows no survival advantage, many older patients receive primary androgen-deprivation therapy (PADT) shortly after the diagnosis of localized prostate cancer (PCa).
This study evaluates whether the early use of PADT affects the subsequent receipt of additional palliative cancer treatments such as chemotherapy, palliative radiation therapy, or intervention for spinal cord compression or bladder outlet obstruction.
Design, setting, and participants
This longitudinal population-based cohort study consists of Medicare patients aged ≥66 yr diagnosed with localized PCa from 1992 to 2006 in areas covered by the Surveillance Epidemiology and End Results (SEER) program. SEER-Medicare linked data through 2009 were used to identify the use of PADT and palliative cancer therapy.
Outcome measurements and statistical analysis
Instrumental variable analysis methods were used to minimize confounding effects. Confidence intervals were derived from the bootstrap estimates.
Results and limitations
This study includes 29 775 men who did not receive local therapy for T1–T2 PCa within the first year of cancer diagnosis. Among low-risk patients (Gleason score 2–7 in 1992–2002 and Gleason score 2–6 in 2003–2006) with a median age of 78 yr and a median follow-up of 10.3 yr, PADT was associated with a 25% higher use of chemotherapy (hazard ratio [HR]: 1.25; 95% confidence interval [CI], 1.08–1.44) and a borderline higher use of any palliative cancer surgery (HR: 1.07; 95% CI, 0.97– 1.19) within 10 yr of diagnosis in regions with high PADT use compared with regions with low PADT use. Because this study was limited to men >65 yr, the results may not be applicable to younger patients.
Early treatment of low-risk, localized PCa with PADT does not delay the receipt of subsequent palliative therapies and is associated with an increased use of chemotherapy.
Prostatic neoplasm; Medicare; SEER program; Antineoplastic agents–hormonal
Targeting multiple anti-apoptotic proteins is now possible with the small molecule BH3 domain mimetics such as ABT-737. Given recent studies demonstrating that autophagy is a resistance mechanism to multiple therapeutic agents in the setting of apoptotic inhibition, we hypothesized that hydroxychloroquine (HCQ), an anti-malarial drug that inhibits autophagy, will increase cytotoxicity of ABT-737.
Cytotoxicity of ABT-737 and HCQ was assessed in vitro in PC-3 and LNCaP cells, and in vivo in a xenograft mouse model. The role of autophagy as a resistance mechanism was assessed by siRNA knockdown of the essential autophagy gene beclin1. ROS was measured by flow cytometry, and mitophagy assessed by the mCherry-Parkin reporter.
Induction of autophagy by ABT-737 was a mechanism of resistance in prostate cancer cell lines. Therapeutic inhibition of autophagy with HCQ increased cytotoxicity of ABT-737 both in vitro and in vivo. ABT-737 induced LC-3 and decreased p62 expression by immunoblot in cell lines and by immunohistochemistry in tumors in vivo. Assessment of ROS and mitochondria demonstrated that ROS production by ABT-737 and HCQ was a mechanism of cytotoxicity.
We demonstrated that autophagy inhibition with HCQ enhances ABT-737 cytotoxicity in vitro and in vivo, that LC-3 and p62 represent assessable markers in human tissue for future clinical trials, and that ROS induction is a mechanism of cytotoxicity. These results support a new paradigm of dual targeting of apoptosis and autophagy in future clinical studies.
Prostate Cancer; Autophagy; Metabolism; Bcl-2; BH3; ABT-737; ABT-263
Previous studies suggest that obesity is associated with higher prostate cancer progression and mortality despite an association with lower prostate cancer incidence. This study aims to better understand these apparently inconsistent relationships among obese men, by combining evidence from three nationally representative cross-sectional surveys.
We evaluated relationships between obesity and (1) testosterone concentrations in the Third National Health and Nutrition Examination Survey (NHANES III; n=845), (2) prostate-specific antigen (PSA) in NHANES 2001–2004 (n=2,458) and (3) prostate biopsy rates in the National Health Interview Survey (NHIS 2000; n=4,789) population. Mean testosterone, PSA concentrations and biopsy rates were computed for body mass index (BMI) categories.
Testosterone concentrations were inversely associated with obesity (p-trend<0.0001) in NHANES III. In NHANES 2001–2004 obese (BMI >35) versus lean (BMI <25) men were less likely to have PSA concentrations that reached the biopsy threshold of >4 ng/ml (3% versus 8%; p<0.0001). Among NHIS participants all BMI groups had similar rates of PSA testing (p=0.24). However, among men who had PSA tests, 11% of men with BMI >30 versus 16% with BMI <25, achieved a PSA threshold of 4 ng/ml; p=0.01. Furthermore, biopsy rates were lower among men with BMI >30 versus BMI <25 in NHIS participants (4.6% vs. 5.8%; p=0.05).
Obesity was associated with lower PSA-driven biopsy rates. These data support further studies to test the hypothesis that obesity affects prostate cancer detection independent of prostate cancer risk by decreasing the PSA-driven biopsy rates.
obesity; prostate cancer; prostate-specific antigen; biopsy
Abiraterone acetate is an orally administered potent inhibitor of cytochrome P450, family 17, subfamily A, polypeptide 1 (CYP17A1 or CYPc17), which is essential for synthesis of testosterone from cholesterol. While decreasing serum testosterone through inhibition of testicular function is the first line of treatment for men with metastatic prostate cancer, residual androgens may still be detected in patients treated with LHRH agonists. Treatment with abiraterone results in rapid, and complete, inhibition of androgen synthesis in the adrenal glands and within the tumor itself. An overall survival benefit of maximal androgen suppression was recently demonstrated in a randomized placebo controlled phase III clinical trial of abiraterone with prednisone versus prednisone in men with metastatic castrate resistant prostate cancer previously treated with docetaxel chemotherapy. Abiraterone’s efficacy demonstrates the importance of androgen signaling in patients with castrate resistant metastastic disease, and the importance of studies of other novel agents such as MDV3100, an androgen receptor inhibitor, that additionally targets androgen receptor translocation. These promising results now pose a new angle to an old problem regarding hormonal therapy and raise new questions about how resistance develops, how to best sequence therapy, and how to optimize combinations with other emerging novel targeted agents.
Abiraterone; Prostate Cancer; CYP17A1; CYP17; CYPc17
R-(-)-gossypol acetic acid (AT-101), a natural BH3 mimetic, is investigated in a Phase I/II clinical trial for the treatment of advanced solid tumor malignancies. Gossypol undergoes rapid degradation in solution phase, which causes major technical difficulty for its quantitation in plasma. We developed and validated a sensitive HPLC assay for pharmacokinetic evaluation of gossypol. Acetonitrile deproteinization method was chosen for sample preparation and Schiff's base derivative, R-(-)-gossypol-diamino-propanol (GDP), was used as internal standard. Chromatographic separation of gossypol in plasma was performed using a Zorbax Eclipse XDB column C18 at 30°C. The mobile phase consists of 10 mmol/L KH2PO4 (pH=3.0) and acetonitrile (20:80) at 1.0 mL/min flow rate. Linearity ranged over 56-3585 ng/mL (R2=0.9997±0.0003, n=4), and the limit of detection was 28 ng/mL. The intra- and inter-assay precision was less than 13.7% and the bias ranged from -7.4 to 7.0%. The method was successfully applied to characterize the pharmacokinetics of AT-101 in a Phase I clinical trial. The validated assay is accurate, and sensitive with minimum loss and rapid analysis time and suitable for quantification of gossypol for pharmacokinetics evaluation.
R-(-)-gossypol; HPLC-UV; pharmacokinetics
Drug interactions can have a significant impact on the response to combinatorial therapy for anticancer treatment. In some instances these interactions can be anticipated based on pre-clinical models. However, the anticipation of drug interactions in the clinical context is in general a challenging task.
Here we propose the pooled analysis of clinical trials as a mean to investigate drug interactions in anticancer therapy. To this end we collected 1,163 Phase II clinical trials with response data on over 53,745 subjects.
We provide statistical definitions of drugs resulting in clinical synergy and antagonism and identify drug combinations in each group. We also quantify the possibility of inferring interactions between three or more drugs from parameters characterizing the action of single and two-drugs combinations.
Our analysis provides a statistical methodology to track the performance of drug combinations in anticancer therapy and to quantify drug interactions in the clinical context.
Cancer therapy; Clinical trial; Overall response rate; Combinatorial therapies; Clinical synergy; Systems biology
Ixabepilone is an epothilone B analogue with activity in a variety of solid malignancies, including prostate cancer. The main dose-limiting toxicity of ixabepilone is myelosuppression when administered by using an every 3-week schedule. Here we evaluate the activity of a weekly ixabepilone in men with metastatic castrate-resistant prostate cancer to minimize hematologic toxicity.
BMS-247550 (ixabepilone) is an epothilone B analogue with activity in taxane-resistant cancer cell lines. Here we report the activity and toxicity of ixabepilone, administered by using a weekly schedule, in men with metastatic castrate-resistant prostate cancer (CRPC).
Patients with metastatic CRPC received ixabepilone at 20 mg/m2 intravenous weekly × 3, in 4-week cycles. This noncomparative study stratified patients to either a chemotherapy naive (CN), prior taxane (Tax) only, or 2 prior cytotoxic (TCx) chemotherapy arm. The primary endpoint was prostate-specific antigen response by using PCWG (Prostate Cancer Working Group) 1 criteria. Secondary endpoints included radiographic response when using RECIST (Response Evaluation Criteria In Solid Tumors).
In total, 124 patients were enrolled, of whom, 109 were eligible (35 CN, 42 Tax, and 32 TCx) for the primary response determination in this study. Prostate-specific antigen responses were seen in 12 (34.3%) of 35, 12 (28.6%) of 42, and 7 (21.9%) of 32 patients with the partial objective response in 5 (22.7%) of 22, 2 (8.0%) of 25, and 0 (0.0%) of 24 patients for the CN, Tax, and TCx arms, respectively. Significant (grade 3/4) neutropenia was seen in 6 (15.4%), 7 (14.6%), and 9 (25.0%); and grade 3/4 sensory neuropathy was seen in 8 (20.5%), 12 (25.0%), and 12 (33.3%) for CN, Tax, and TCx, respectively. Grade 3/4 thrombocytopenia was infrequent and seen in only one patient on the CN and the TCx arm.
Ixabepilone was found to have an acceptable toxicity profile when administered by using a weekly schedule with less myelosuppression compared with prior studies when using the every 3-week schedule. Single-agent activity was observed and met prespecified activity levels for the Tax treated arm.
BMS-247550; Chemotherapy; Epothilone; Microtubule-inhibitor
Despite controversy over the benefit of prostate specific antigen (PSA) screening, little is known about risk profiles and treatment patterns in men diagnosed with prostate cancer who have a PSA value less than or equal to 4 ng/mL.
We utilized data from the Surveillance, Epidemiology, End Results system to describe patient characteristics and treatment patterns of 123,934 men with newly diagnosed prostate cancer in 2004–2006. Age-standardized treatment rates were calculated in five-year age strata. Logistic regression was used to quantify the odds ratios (OR) of men with low– and high–risk disease and the use of radical prostatectomy (RP) or radiation therapy (RT).
Men with a PSA of 4.0 ng/ml or less represent 14% of incident prostate cancer cases. Fifty-four percent of men diagnosed with prostate cancer and PSA ≤ 4.0 ng/mL harbor low-risk disease (stage ≤ T2a, PSA level ≤ 10 ng/mL, and Gleason score ≤ 6), but over 75% of them received RP or RT. Men with screen-detected prostate cancer and PSA values ≤ 4 ng/mL were 1.49 (CI 1.38–1.62) and 1.39 (CI 1.30–1.49) times more likely to receive RP and RT, respectively, and were less likely to have high-grade disease than men who had non-screen detected prostate cancer (OR=0.67; 95% CI:0.60–0.76).
Most men diagnosed with prostate cancer with a PSA threshold ≤ 4.0 ng/mL had low-risk disease but underwent aggressive local therapy. Lowering biopsy threshold, while lacking the ability to distinguish indolent cancers from aggressive cancers, may increase overdiagnosis and overtreatment.
Activation of the epidermal growth factor pathway is important in prostate cancer development and the transcription of androgen receptor regulated genes. This study evaluated the potential activity of lapatinib in men with biochemically-relapsed androgen-dependent (stage D0) prostate cancer.
Patients with a rising PSA after primary therapy for prostate cancer were enrolled. A PSA doubling time (PSADT) <12 months was required. Lapatinib was administered at 1,500 mg orally daily. Outcome measures were changes in PSA kinetics. Primary tumor blocks were obtained and assessed for EGFR expression, EGFR Q787Q polymorphism, and Kras 38 mutational status.
49 patients were enrolled (14 ineligible), resulting in 35 pts for analysis. No PSA response was observed; best response was stable disease (n=28, 80.0%). Pre-treatment average slope was 0.19 log (PSA)/month (PSADT=3.70 months), in contrast to on-treatment average slope of 0.13 log (PSA)/month (PSADT=5.44 months) using linear mixed effects models (p=0.006). Median progression-free survival (PFS) was 17.4 months for the high EGFR group and 6.0 months for the low EGFR group (p=0.50). Patients with Kras 38 mutation had shorter PFS than those without Kras 38 mutation (p=0.09).
Although no PSA responses (primary endpoint) was observed, lapatinib may have biologic activity in men with stage D0 prostate cancer as evidenced by a decrease in PSA slope in this non-randomized study. Additional trials assessing the role of EGFR overexpression and Kras wild type status in prostate cancer should be investigated.
Epidermal growth factor receptor; tyrosine kinase inhibitors; clinical trial
Integrins are involved in prostate cancer metastasis by regulating cell adhesion, migration, invasion, motility, angiogenesis and bone metabolism. We evaluated the efficacy of two dose levels of cilengitide in patients (pts) with castrate resistant prostate cancer (CRPC).
Chemotherapy-naïve, asymptomatic metastatic CRPC pts were randomized to cilengitide 500mg or 2000mg IV twice weekly using parallel 2-stage design. The primary endpoint was rate of objective clinical progression at six-months. Secondary endpoints included clinical and PSA response rates, safety and effects of cilengitide treatment on circulating tumor cells (CTCs) and bone remodeling markers.
Forty-four pts were accrued to first stage (22/arm). Median number of cycles was three in both arms (500mg arm: 1–8; 2000 mg arm: 1–15). At six months, two pts (9%) on the 500mg arm and five pts (23%) on the 2000mg arm had not progressed. Best objective response was stable disease (SD) in seven pts for 9.9[8.1,20.9] months. There were three grade 3 and no grade 4 toxicities. At 12 weeks, analysis of bone markers did not reveal significant trends. At progression, bone specific alkaline phosphatase and N-telopeptide increased in all pts, less so in pts on the 2000mg arm and in pts on both arms who obtained SD at 6 months. CTCs increased over time in both arms.
Cilengitide was well tolerated with modest clinical effect in favor of the higher dose. The unique trial design including a shift from response rate to objective progression as the endpoint, and not acting on PSA increases was feasible.
prostate cancer; metastatic disease; integrins; angiogenesis; cilengitide; bone biomarkers
Integrins mediate invasion and angiogenesis in prostate cancer bone metastases. We conducted a phase II study of Cilengitide, a selective antagonist of αvβ3 and αvβ5 integrins, in non-metastatic castration resistant prostate cancer with rising PSA.
Patients were observed for 4 weeks with PSA monitoring, and then treated with 2,000 mg IV of cilengitide twice weekly until toxicity/progression. PSA, circulating tumor cells (CTCs) and circulating endothelial cells (CECs) were monitored each cycle with imaging performed every 3 cycles. Primary end point was PSA decline by ≥ 50%. Secondary endpoints were safety, PSA slope, time to progression (TTP), overall survival (OS), CTCs, CECs and gene expression.
16 pts were enrolled; 13 were eligible with median age 65.5 years, baseline PSA 8.4 ng/mL and median Gleason sum 7. Median of 3 cycles was administered. Treatment was well tolerated with 2 grade 3 toxicities and no grade 4 toxicities. There were no PSA responses; 11 patients progressed by PSA after 3 cycles. Median TTP was 1.8 months and median OS has not been reached. Median pre- and on-treatment PSA slopes were 1.1 and 1.8 ng/mL/month. Baseline CTCs were detected in 1/9 patients. CTC increased (0 to 1; 2 pts), remained at 0 (2 pts) or decreased (23 to 0; 1 patient) at progression. Baseline median CEC was 26 (0–61) and at progression, 47 (15–148). Low cell counts precluded gene expression studies.
Cilengitide was well tolerated but had no detectable clinical activity. CTCs are of questionable utility in non-metastatic prostate cancer.
EMD 121974; cilengitide; non-metastatic prostate cancer
mTOR inhibitors are used clinically to treat renal cancer but are not curative. Here we show that autophagy is a resistance mechanism of human renal cell carcinoma (RCC) cell lines to mTOR inhibitors. RCC cell lines have high basal autophagy that is required for survival to mTOR inhibition. In RCC4 cells, inhibition of mTOR with CCI-779 stimulates autophagy and eliminates RIP kinases (RIPKs) and this is blocked by autophagy inhibition, which induces RIPK- and ROS-dependent necroptosis in vitro and suppresses xenograft growth. Autophagy of mitochondria is required for cell survival since mTOR inhibition turns off Nrf2 antioxidant defense. Thus, coordinate mTOR and autophagy inhibition leads to an imbalance between ROS production and defense, causing necroptosis that may enhance cancer treatment efficacy.
The kinesin spindle protein (KSP) is essential for separation of spindle poles during mitosis. Its inhibition results in mitotic arrest. This phase I trial examined safety, tolerability, dose-limiting toxicity (DLT), maximum tolerated dose (MTD), pharmacokinetic parameters, and anti-tumor activity of MK-0731, a potent inhibitor of KSP.
In part 1, patients with advanced solid tumors received MK-0731 intravenously over 24 h every 21 days starting at 6 mg/m2, escalating until MTD was reached. In part 2, patients with taxane-resistant tumors received the MTD. Plasma samples were collected to analyze the pharmacokinetics of MK-0731. Tumor response was evaluated using Response Evaluation Criteria in Solid Tumors (RECIST) v1.0.
In part 1, 21 patients (median age 63 years) were treated with MK-0731 at doses ranging from 6 to 48 mg/m2/24 h for median four cycles. The dose-limiting toxicity was neutropenia and the MTD was 17 mg/m2/24 h. At the MTD, AUC (±SD) was 10.5 (±7.3) μM × hour, clearance (±SD) was 153 mL/min (±84), and t1/2 was 5.9 h. In part 2, 22 patients received the MTD and there were no DLTs. Although there were no objective tumor responses, four patients (with cervical, non-small cell lung, and ovarian cancers) had prolonged stable disease.
MK-0731 at the MTD of 17 mg/m2/day every 21 days in patients with solid tumors had few grade 3 and 4 toxicities with the major DLTs at higher doses being myelosuppression. Anti-tumor efficacy was suggested by the length of stable disease in selected patients with taxane-resistant tumors.
Kinesin spindle protein; Oncology; Neutropenia
Given prior studies demonstrating the marked clinical activity of oral estrogens in prostate cancer, more recent data demonstrating the safety of transdermal estradiol, and the renewed interest in targeting testosterone metabolism and androgen receptor pathways, we report the results of a trial of transdermal estradiol in advanced heavily pre-treated castrate and chemotherapy refractory patients.
Patients with prostate cancer progressing after androgen ablation therapy and chemotherapy were treated with transdermal estradiol patches (0.4 mg per 24 hours total) applied weekly and assessed for tolerability and biochemical activity.
Twenty-two patients were treated on study with all patients evaluable for safety and 20 patients evaluable for response. All patients had aggressive and resistant disease, as demonstrated by a median PSA of 170 ng/mL (range 14 to 5030 ng/mL), with more than 60% having been treated with two or more prior chemotherapy regimens, and 20% with visceral disease. Nine patients had a decrease in PSA, of which two patients had a PSA response defined as a decline in PSA by 50%. Therapy was well tolerated and no thrombotic events were observed.
In heavily pre-treated patients with advanced castrate and chemotherapy refractory metastatic prostate cancer, transdermal estradiol was safe and had biochemical activity. These data support further studies to understand if transdermal estradiol can be useful following multiple standard therapies.
estradiol; abiraterone; testosterone; prostate cancer
Autophagy is an evolutionarily conserved, intracellular self-defense mechanism where organelles and proteins are sequestered into autophagic vesicles (AVs) that are subsequently degraded through fusion with lysosomes. Cells thereby prevent the toxic accumulation of damaged or unnecessary components, but also recycle these components to sustain metabolic homoeostasis. Heightened autophagy is a mechanism of resistance for cancer cells faced with metabolic and therapeutic stress, revealing opportunities for exploitation as a therapeutic target in cancer. We summarize recent developments in the field of autophagy and cancer, and build upon the results presented at the Cancer Therapeutics and Evaluation Program (CTEP) Early Drug Development meeting in March, 2010. Herein, we describe our current understanding of the core components of the autophagy machinery, the functional relevance of autophagy within the tumor microenvironment and outline how this knowledge has informed preclinical investigations combining the autophagy inhibitor hydroxychloroquine (HCQ) with chemotherapy, targeted therapy and immunotherapy. Finally, we describe ongoing clinical trials involving HCQ as a first generation autophagy inhibitor, as well as strategies for the development of novel, more potent and specific inhibitors of autophagy.
In the present study, we determined the effects of a γ-tocopherol-rich mixture of tocopherols (γ-TmT) on the growth and apoptosis of cultured human prostate cancer LNCaP cells. We also determined the effects of dietary γ-TmT on the formation and growth of LNCaP tumors in immunodeficient mice. In the in vitro study, we found that the activity of γ-TmT was stronger than α-tocopherol for inhibiting the growth and stimulating apoptosis in LNCaP cells. In the animal study, treatment of severe combined immunodeficient (SCID) mice with dietary γ-TmT inhibited the formation and growth of LNCaP xenograft tumors in a dose-dependent manner. Mechanistic studies showed that γ-TmT administration inhibited proliferation as reflected by decreased mitosis and stimulated apoptosis as reflected by increased caspase-3 (active form) expression in LNCaP tumors. In addition, dietary administration of γ-TmT increased the levels of α-, γ- and δ- tocopherol in plasma, and increased levels of γ- and δ- tocopherol were also observed in the prostate and in tumors. The present study demonstrated that γ-TmT had strong anticancer activity both in vitro and in vivo. Additional studies are needed to determine the potential preventive effect of γ-TmT for prostate cancer in humans.
prostate cancer; tocopherol; immunodeficient mice; xenograft tumor
As the most preventable cause of death in the world today, understanding tobacco use among one of the fastest growing ethnic/racial groups is warranted. We explore cigarette and smokeless tobacco (SLT) use among South Asians in NJ and the Northeast using the Tobacco Use Supplement to the Current Population Survey. Overall, tobacco use rates among South Asians were similar or lower than the population. However, in NJ, South Asian males had the highest SLT rate (2.7%) and in the Northeast, White (AOR = 5.8, 95% CI = 3.7–9.4) and South Asian males (AOR = 4.0, 95% CI = 1.5–10.6) had significantly higher odds of current SLT use relative to non-White males. Tobacco use among South Asians was not homogeneous; Pakistanis are overrepresented among cigarette smokers while Indians are overrepresented among SLT users. Given the differential tobacco use among and within South Asian, disaggregating data to understand tobacco use behaviors is necessary to develop effective interventions for tobacco cessation.
National-level data that characterize contemporary prostate cancer patients are limited. We used 2004–2005 data from the Surveillance, Epidemiology, and End Results Program to generate a contemporary profile of prostate cancer patients (N = 82 541) and compared patient characteristics of this 2004–2005 population with those of patients diagnosed in 1998–1989 and 1996–1997. Among newly diagnosed patients in 2004–2005, the majority (94%) had localized (ie, stage T1 or T2) prostate cancer and a median serum prostate-specific antigen (PSA) level of 6.7 ng/mL. Between 1988–1989 and 2004–2005, the average age at prostate cancer diagnosis decreased from 72.2 to 67.2 years, and the incidence rate of T3 or T4 cancer decreased from 52.7 per 100 000 to 7.9 per 100 000 among whites and from 90.9 per 100 000 to 13.3 per 100 000 among blacks. In 2004–2005, compared with whites, blacks were more likely to be diagnosed at a younger age (mean age: 64.7 vs 67.5 years, difference = 2.7 years, 95% confidence interval [CI] = 2.5 to 2.9 years, P < .001) and to have a higher PSA level at diagnosis (median PSA level: 7.4 vs 6.6 ng/mL, difference = 0.8 ng/mL, 95% CI = 0.6 to 1.0 ng/mL, P < .001). In conclusion, more men were diagnosed with prostate cancer at a younger age and earlier stage in 2004–2005 than in earlier years. The racial disparity in cancer stage at diagnosis has decreased statistically significantly over time.
Most newly diagnosed prostate cancer is clinically localized, and major treatment options include surgery, radiation, or conservative management. Although conservative management can be a reasonable choice, there is little contemporary PSA era data on outcomes with this approach.
To evaluate the outcomes of clinically localized prostate cancer managed without initial attempted curative therapy in the PSA era.
A population-based cohort study with a median follow-up 8.3 years (through December 31, 2007). Competing risk analyses were performed to assess outcomes.
Areas covered by the Surveillance, Epidemiology and End Results (SEER) program.
Men diagnosed with stage T1/T2 prostate cancer after age 65 between 1992 and 2002 managed without surgery or radiation within 6 months of cancer diagnosis.
Main Outcome Measure:
10-year overall survival, cancer-specific survival, and major cancer related interventions.
With a median age of 78 years at cancer diagnosis, ten-year prostate cancer-specific mortality was 8.3% (95% CI 4.2% – 12.8%), 9.1% (95% CI 8.3% - 10.1%), and 25.6% (95% CI 23.7% - 28.3%) for men with well-, moderately-, and poorly-differentiated tumors, respectively. The corresponding 10-year risks of dying of competing causes were 59.8% (95% CI 53.2% - 67.8%), 57.2% (95% CI 52.6% - 63.9%) and 56.5% (95% CI 53.6% - 58.8%), respectively. Ten-year disease specific mortality for men aged 66-74 years diagnosed with moderately-differentiated disease was 60% - 74% lower than earlier studies: 6% (95% confidence interval [CI] 4% - 8%) in the contemporary PSA era (1992-2002) compared to results of previous studies (15% - 23%) in earlier eras (1949-1992). Improved survival was also observed in poorly-differentiated disease. The use of chemotherapy (1.6%), or major interventions for spinal cord compression (0.9%), was uncommon.
Results following conservative management of clinically localized prostate cancer diagnosed in 1992 – 2002 are better than outcomes among patients diagnosed in the 1970s and 1980s. This may be due, in part, to additional lead time, overdiagnosis related to PSA testing, grade migration, or advances in medical care.
prostatic neoplasm; survival; population-based study
There is no effective second line systemic chemotherapy for patients with disease progression following cisplatin-based chemotherapy. A phase II trial of sorafenib was performed to determine the activity and toxicity of this agent in a multiinstitutional setting in patients previously treated with 1 prior chemotherapy regimen.
27 patients with advanced urothelial carcinoma were treated with sorafenib 400 mg orally twice daily continuously until progression or unacceptable toxicity.
There were no objective responses observed. The 4-month progression free survival (PFS) rate was 9.5% , median overall survival of the group was 6.8 months. There were no therapy related deaths, and common grade 3 toxicities included fatigue and hand-foot syndrome
Although sorafenib as a single agent has minimal activity in patients with advanced urothelial cancer in the second line setting, further investigation of tyrosine kinase inhibitors using different trial designs with PFS endpoints is warranted.
urothelial cancer; sorafenib
Apoptosis resistance is a hallmark of cancer linked to disease progression and treatment resistance, which has led to the development of anticancer therapeutics that restore apoptotic function. Antiapoptotic Bcl-2 is frequently overexpressed in refractory prostate cancer and increased following standard hormonal therapy and chemotherapy; however, the rationally designed Bcl-2 antagonist, ABT-737, has not shown single agent apoptosis-promoting activity against human prostate cancer cell lines. This is likely due to the coordinate expression of antiapoptotic, Bcl-2–related Mcl-1 that is not targeted by ABT-737. We developed a mouse model for prostate cancer in which apoptosis resistance and tumorigenesis were conferred by Bcl-2 expression. Combining ABT-737 with agents that target Mcl-1 sensitized prostate cancer cell lines with an apoptotic block to cell death in vitro. In mice in vivo, ABT-737 showed single agent efficacy in prostate tumor allografts in which tumor cells are under hypoxic stress. In human prostate cancer tissue, examined using a novel tumor explant system designated Tumor Tissue Assessment for Response to Chemotherapy, combination chemotherapy promoted efficient apoptosis. Thus, rational targeting of both the Bcl-2 and Mcl-1 mechanisms of apoptosis resistance may be therapeutically advantageous for advanced prostate cancer.
Macroautophagy (autophagy) is a lysosomal degradation pathway for the breakdown of intracellular proteins and organelles. Although, constitutive autophagy is a homeostatic mechanism for intracellular recycling and metabolic regulation, autophagy is also stress responsive where it is important for the removal of damaged proteins and organelles. Autophagy thereby confers stress tolerance, limits damage and sustains viability under adverse conditions. Autophagy is a tumor suppression mechanism yet it enables tumor cell survival in stress. Reconciling how loss of a prosurvival function can promote tumorigenesis, emerging evidence suggests that preservation of cellular fitness by autophagy may be key to tumor suppression. As autophagy is such a fundamental process, establishing how the functional status of autophagy influences tumorigenesis and treatment response is important. This is especially critical as many current cancer therapeutics activate autophagy. Therefore, efforts to understand and modulate the autophagy pathway will provide new approaches to cancer therapy and prevention.
Allelic loss of the essential autophagy gene beclin1 occurs in human cancers and renders mice tumor-prone suggesting that autophagy is a tumor-suppression mechanism. While tumor cells utilize autophagy to survive metabolic stress, autophagy also mitigates the resulting cellular damage that may limit tumorigenesis. In response to stress, autophagy-defective tumor cells preferentially accumulate p62/SQSTM1 (p62), endoplasmic reticulum (ER) chaperones, damaged mitochondria, reactive oxygen species (ROS), and genome damage. Moreover, suppressing ROS or p62 accumulation prevented damage resulting from autophagy defects indicating that failure to regulate p62 caused oxidative stress. Importantly, sustained p62 expression resulting from autophagy defects was sufficient to alter NF-κB regulation and gene expression and to promote tumorigenesis. Thus defective autophagy is a mechanism for p62 upregulation commonly observed in human tumors that contributes directly to tumorigenesis likely by perturbing the signal transduction adaptor function of p62 controlling pathways critical for oncogenesis.
autophagy; beclin1; atg5; genomic instability; p62; NF- κB; DNA damage; cancer
Prostate-specific antigen progression (PSA-P) is an indicator of progression in hormone-sensitive (HS) and castration-resistant (CR) prostate cancer (PC). We evaluated different definitions of PSA-P as predictors of overall survival (OS).
Patients and Methods
A total of 1,078 patients with HSPC who were on hormones (Southwest Oncology Group [SWOG] trial 9346 [S9346]) and 597 patients with CRPC who were treated with chemotherapy (SWOG trial 9916 [S9916]) were eligible for this analysis. PSA-P definitions tested included the following: PSA Working Group, Prostate Cancer Working Group (PCWG 2008), and other definitions. A time-varying approach analyzed associations between PSA-P at any time and OS. A landmark analysis examined the relationship between PSA-P status at 7 months for S9346, or 3 months for S9916, and subsequent OS.
In the time-varying analysis, both working groups definitions were strongly associated with OS (P < .001) in both study settings. In patients enrolled onto S9346, both definitions predicted a 2.4-fold increased risk of death (ROD) and a greater than four-fold increased ROD if PSA-P occurred in the first 7 months. In S9916, they predicted a 40% increase in ROD and a two-fold increase in ROD if PSA-P occurred at 3 months. In landmark analyses of patients on S9346 by using the PCWG 2008 definition of PSA-P, median subsequent OS was 10 months versus 44 months in patients who did or did not have PSA-P by 7 months, respectively; in S9916, data were 11 months versus 18 months for patients who did or did not have PSA-P by 3 months, respectively.
PSA-P, defined as an increase of ≥ 25% greater than the nadir and an absolute increase of at least 2 or 5 ng/mL, predicts OS in HSPC and CRPC and may be a suitable end point for phase II studies in these settings.
During tumorigenesis, normal growth mechanisms are deregulated and safeguards that eliminate abnormal cells by apoptosis are disabled. Tumor cells must also increase nutrient uptake and angiogenesis to support the upregulation of metabolism necessary for unrestricted growth. In addition, they have to rely on inefficient energy production by glycolysis. This glycolytic state can result from mutations that promote cell proliferation, the hypoxic tumor microenvironment and perhaps mitochondrial malfunction. Moreover, the very signals that enable unrestricted cell proliferation inhibit autophagy, which normally sustains cells during nutrient limitation. In tumors, inactivation of the autophagy pathway may enhance necrosis and inflammation and promote genomic instability, which can further enhance tumor growth. Thus, tumor cells cannot adapt efficiently to metabolic stress and could be induced to die by metabolic catastrophe, in which high energy demand is contrasted by insufficient energy production. Efforts to exploit this unique metabolic state clinically previously focused mainly on detecting tissue displaying increased glycolytic metabolism. The challenge now is to induce metabolic catastrophe therapeutically as an approach to killing the unkillable cells.
Autophagy; Apoptosis; AKT; mTOR; BCL-2; Beclin1; Cancer