Change in serum prostate-specific antigen as a marker of response to cytotoxic therapy for hormone-refractory prostate cancer

Cytoreductive radical prostatectomy: who benefits from the surgical approach?

PURPOSE OF REVIEW

Local treatment in oligometastatic prostate cancer patients is associated with improved survival. Nevertheless, in term of surgery, cytoreductive radical prostatectomy has no level of evidence 1 and is an individual treatment approach. We reviewed the recent literature to highlight parameters for selecting patients for a surgical approach.

RECENT FINDINGS

Retrospective data on oncologic outcome for cytoreductive prostatectomy are confirmed. We identified several parameters that help to select patients for surgery. Patients with a favorable prostate-specific antigen (PSA) decline after androgen deprivation therapy (ADT) have excellent oncologic long-term control. Circulating tumor cells (CTC's) are frequently analyzed in more advanced prostate cancer. In case of C-reactive protein (CRP) at least a longer interval to develop castration resistant prostate cancer (CRPC) is shown in case of low CTC count at time of surgery. Nutrition status analyzed as the hemoglobin, albumin, lymphocyte, and platelet (HALP)-score is of significant value in demonstrating an effect of CRP.

SUMMARY

From retrospective findings we have several clinical and basic science parameters to select patients for CRP. PSA at the time of surgery is the most frequently analyzed one, whereas CTC and HALP-score are promising tools to select patients that need to be validated.

Imaging-based representation and stratification of intra-tumor heterogeneity via tree-edit distance

Personalized medicine is the future of medical practice. In oncology, tumor heterogeneity assessment represents a pivotal step for effective treatment planning and prognosis prediction. Despite new procedures for DNA sequencing and analysis, non-invasive methods for tumor characterization are needed to impact on daily routine. On purpose, imaging texture analysis is rapidly scaling, holding the promise to surrogate histopathological assessment of tumor lesions. In this work, we propose a tree-based representation strategy for describing intra-tumor heterogeneity of patients affected by metastatic cancer. We leverage radiomics information extracted from PET/CT imaging and we provide an exhaustive and easily readable summary of the disease spreading. We exploit this novel patient representation to perform cancer subtyping according to hierarchical clustering technique. To this purpose, a new heterogeneity-based distance between trees is defined and applied to a case study of prostate cancer. Clusters interpretation is explored in terms of concordance with severity status, tumor burden and biological characteristics. Results are promising, as the proposed method outperforms current literature approaches. Ultimately, the proposed method draws a general analysis framework that would allow to extract knowledge from daily acquired imaging data of patients and provide insights for effective treatment planning.

Abiraterone acetate plus Prednisone/Prednisolone compared with Enzalutamide in metastatic castration resistant prostate cancer before or after chemotherapy: A retrospective study of real‐world data (ACES)

Background

Abiraterone acetate combined with Prednisone/Prednisolone (AA+P) and Enzalutamide (ENZ) have proven survival benefit in men with metastatic castration‐resistant prostate cancer (mCRPC) in chemotherapy‐naïve and prior chemotherapy patients. There have been no studies directly comparing the effectiveness of ENZ to AA+P in mCRPC patients.

Methods

A retrospective, survival analysis study of 143 real‐world mCRPC patients (90 in AA+P and 53 in ENZ group) was conducted. Patients who started their treatment between February 2012 and May 2016 were included. The primary end point was biochemical progression‐free survival (bPFS). Secondary end points were radiological progression‐free survival (rPFS) and overall survival (OS). Toxicity data were also collected. Data were analyzed using Cox proportional hazards (PH) models, adjusting for covariates: prior radical treatment; Gleason score; prostate‐specific antigen; age; and chemotherapy naïve or not.

Results

After median follow‐up of 15 months (interquartile range 7 to 23), 112 events of biochemical progression were observed (71 in AA+P and 41 in ENZ). About 41% in AA+P group and 30% patients in ENZ group received prior chemotherapy. The chance of biochemical progression was significantly lower among ENZ patients than AA+P patients, when adjusting for all covariates in the Cox PH model (hazard ratio [HR] 0.54, 95% confidence interval [CI] 0.35 to 0.82, P = .004). There was a trend implying the chance of rPFS could be higher among ENZ patients than AA+P patients (HR 1.24, 95% CI 0.76 to 2.02, P = .4). There is no difference in OS between ENZ and AA+P patients, when adjusting for all covariates in the Cox PH model (HR 0.91, 95% CI 0.59 to 1.41, P = .7). About 38% of ENZ patients reported fatigue compared to 16% of AA+P patients, while hypertension was reported slightly more in AA+P patients.

Conclusions

This study showed a statistically significant difference in bPFS, favoring ENZ, but no significant difference in rPFS or OS.

Feasibility Study and Preliminary Results of Prognostic Value of Bone SPECT-CT Quantitative Indices for the Response Assessment of Bone Metastatic Prostate Carcinoma to Abiraterone

Objective: We assessed the prognostic value of quantitative indices extracted from bone SPECT-CT to evaluate the response of bone metastatic castrate-resistant prostate cancer (BmCRPC) to abiraterone.

Methods: Consecutive patients with BmCRPC initiating treatment with abiraterone from March 2014 to March 2015 were prospectively included. Three 2-bed SPECT-CT [at baseline [M0], after 3 months [M3], and 6 months [M6] of treatment], were planned (Symbia Intevo^®, Siemens). SPECT data were reconstructed using an Ordered Subset Conjugate Gradient Minimization (OSCGM) algorithm allowing SUV quantification. SUVmax and SUVpeak of the highest uptake lesion were measured in each SPECT-CT. Total Neoplastic Osteoblastic Metabolic Volume (NOMV) was assessed. PSA level was recorded at baseline, M3, and M6 of treatment. Overall survival (OS), progression-free survival (PFS), and disease-specific survival (DSS) were calculated.

Results: Nineteen patients aged 71.1 ± 7.7 years were included. Low M0 SUVmax was significantly predictive of longer OS (p = 0.04). Low NOMV at M0 were significantly predictive of longer PFS (p = 0.02). Patients with increase of at least 12.5% of the SUVpeak of the highest uptake lesion between M0 and M3 (ΔSUVpeakM0M3) had a significantly longer OS (p = 0.03). Patients with increase (or decrease lesser than 25%) of ΔSUVpeakM0M3 had a significantly longer DSS (p = 0.01). Patients with increase of NOMV of at least 45% between M0 and M6 had a significantly shorter PFS (p < 0.001). Variations of NOMV between M0 and M6 were significantly correlated with PSA variations between M0 and M6 (rs = 0.73, p = 0.02).

Conclusions: Quantitative bone SPECT-CT appears to be a promising tool of BmCRPC assessment. Early flare-up phenomenon seems to predict longer OS.

Efficacy and safety of abiraterone and enzalutamide for castration-resistant prostate cancer: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Previous evidence directly evaluating the efficacy and safety of abiraterone and enzalutamide treatment for castration-resistant prostate cancer (CRPC) is limited. We aim to include more randomized controlled trials (RCTs) to comprehensively assess the efficacy and safety of abiraterone and enzalutamide treatment.

METHODS

PubMed, Embase, and ClinicalTrial.gov were systematically searched. Pooled hazard ratios (HRs) were calculated using Stata 12.0 software. The comparison of the prostate-specific antigen (PSA) response rate and adverse events (AEs) between the treatment and control groups were performed using RevMan 5.3 software.

RESULTS

Eight eligible RCTs with 6,490 patients were selected. Pooled HRs were 0.72 for overall survival, 0.45 for radiographic progression-free survival (rPFS), and 0.36 for PSA PFS. abiraterone and enzalutamide could significantly increase the PSA response rate OR = 8.67, 95%CI 4.42-17.04) and any AE occurrence (OR = 1.98, 95%CI 1.46-2.68). The treatment group had more occurrence of fatigue (OR = 1.34, 95%CI 1.20-1.49), back pain (OR = 1.15, 95%CI 1.01-1.15), hot flush (OR = 1.76, 95%CI 1.50-2.06), diarrhea (OR=1.22, 95%CI 1.07-2.40) and arthralgia (OR = 1.34, 95%CI 1.16-1.54). Particularly, AEs of special interest including any grade hypertension (OR = 2.06, 95%CI 1.71-2.47), hypokalemia (OR = 1.80, 95%CI 1.42-2.30) and fluid retention or edema (OR = 1.38, 95%CI 1.17-1.63) also occurred less in the control group. Moreover, a higher incidence of high-grade hypertension (OR = 2.60, 95%CI 1.79-3.79) and extremity pain (OR = 4.46, 95%CI 2.81-7.07) was observed in the treatment group.

CONCLUSION

The survival benefits of abiraterone and enzalutamide for CRPC were evident and promising, while the risk of AE occurrence was also acceptably higher in the treatment group than in the placebo group.

The role of salvage lymph node dissection in nonmetastatic castration-resistant prostate cancer: A single center experience

OBJECTIVE

To evaluate oncologic outcomes of patients with nonmetastatic, castration-resistant prostate cancer treated with salvage lymph node dissection (sLND) or androgen-deprivation therapy (ADT) for lymph nodes (LN)-only recurrence.

MATERIALS AND METHODS

Retrospective analysis of 23 (51.1%) patients who underwent sLND and 22 (48.9%) men who received ADT for LN-only recurrence. Biochemical recurrence (BCR) was defined as prostate-specific antigen (PSA) >0.2 ng/ml with an increased trend and radiological recurrence (RAR) was defined as a positive imaging study after sLND or ADT. Second line systemic therapies (SST) were defined as any systemic therapy administered for progression. Predictors of BCR, RAR, and SST were assessed with Cox regression analyses.

RESULTS

Mean PSA reduction was significantly higher after sLND than ADT (62.8% vs. 17.7%; P = 0.04). Clinical outcomes were not statistically different between the 2 groups. However, there was a trend toward a longer time to BCR (13.3 vs. 6 months; P = 0.2) and RAR (21.1 vs. 14.2 months, P = 0.09) in sLND patients than ADT. Median time to SST was longer in the sLND group than ADT (P = 0.04). Univariable Cox regression analyses showed that PSA doubling time and pT stage were associated with RAR and SST (all P < 0.05).

CONCLUSIONS

In patients with nonmetastatic, castration-resistant prostate cancer, sLND resulted in greater PSA decrease than ADT. We noted a nonstatistically significant trend toward longer time to BCR and longer time to RAR for patients treated with sLND than ADT. Additionally, sLND may increase time to SST as compared to ADT.

Vinorelbine and Prednisone in older Cancer Patients with Hormone-Refractory Metastatic Prostate Cancer a Phase II Study

Aims and Background

Prostate cancer is a common disease in older men. Since it is hormone resistant, no treatment may improve survival. In patients with hormone-refractory prostate cancer, clinical benefit is an important treatment end point.

Study Design

This study evaluated the efficacy and toxicity of a vinorelbine and prednisone combination in hormone-refractory prostate cancer patients. Vinorelbine was administered at the dose of 25 mg/m2 on days 1 and 8, every three weeks; prednisone was administered orally at the dose of 12 mg/day. Thirty consecutive patients, 65 years or older, with progressive (PSA increase or increase in bidimensionally measurable lesion) metastatic prostate adenocarcinoma were enrolled. Four patients (13%) had a partial response and 14 (46%) stable disease. Time to progression for the entire group was 4.5 months (range, 2–13) and 7.5 months for the group of responders (range, 3–13). A PSA decrease >50% was registered in 36% of the patients. Pain reduction was recorded in 44.4% of the patients and stability in 14.8%.

Results

The treatment was well tolerated and grade 3 toxicity was found in 2 cases of anemia and 2 cases of leukopenia without fever.

Conclusions

The schedule is able to control the evolution of hormone-refractory prostate cancer and to give a clinical benefit. These results provide information for further clinical trials in a large series of elderly cancer patients.

Safety and Efficacy of First-Line Treatments for Chemotherapy-Naive Metastatic Castration-Resistant Prostate Cancer: A Systematic Review and Indirect Comparison

Recently, several drugs have been introduced for the first-line treatment of chemotherapy-naive metastatic castration-resistant prostate cancer (mCRPC), but few studies have compared treatment outcomes directly. This indirect comparison among 10 clinical trials (n = 4870 patients) retrieved from PubMed, Web of Science, Cochrane Collaboration, and ClinicalTrails.gov was performed to assess the safety and efficacy of docetaxel, cabazitaxel, abiraterone, enzalutamide, and sipuleucel-T for the initial treatment of mCRPC. No significant differences in primary outcome (overall survival) were found among initial treatments. However, docetaxel had the highest probability (37.53%) of being the most effective, but at the cost of more adverse events, while enzalutamide was associated with the best secondary outcomes (prostate-specific antigen response, progression-free survival, quality of life, and adverse event profile). Thus, docetaxel is recommended as the first agent used for the chemotherapy of mCRPC, while enzalutamide is recommended as the first nonchemotherapy treatment. Additional clinical trials are needed to confirm these findings and establish the optimal order for multidrug treatment of mCRPC.

Very Early PSA Response to Abiraterone in mCRPC Patients: A Novel Prognostic Factor Predicting Overall Survival

Background: Abiraterone Acetate (AA) is approved for the treatment of mCRPC after failure of androgen deprivation therapy in whom chemotherapy is not yet clinically indicated and for treatment of mCRPC progressed during or after docetaxel-based chemotherapy regimen. The aim of this study is to evaluate the role of early PSA decline for detection of therapy success or failure in mCRPC patients treated with AA in post chemotherapy setting.

Patients and Methods: We retrospectively evaluated 87 patients with mCRPC treated with AA. Serum PSA levels were evaluated after 15, 90 days and then monthly. The PSA flare phenomenon was evaluated, according to a confirmation value at least 1 week apart. The primary endpoint was to demonstrate that an early PSA decline correlates with a longer progression free survival (PFS) and overall survival (OS). The secondary endpoind was to demonstrate a correlation between better outcome and demographic and clinical patient characteristics.

Results: We have collected data of 87 patients between Sep 2011 and Sep 2014. Early PSA response (≥50% from baseline at 15 days) was found in 56% evaluated patients and confirmed in 29 patients after 90 days. The median PFS was 5.5 months (4.6–6.5) and the median OS was 17.1 months (8.8–25.2). In early responders patients (PSA RR ≥ 50% at 15 days), we found a significant statistical advantage in terms of PFS at 1 year, HR 0.28, 95%CI 0.12–0.65, p = 0.003, and OS, HR 0.21 95% CI 0.06–0.72, p = 0.01. The results in PFS at 1 years and OS reached statistical significance also in the evaluation at 90 days.

Conclusion: A significant proportion (78.6%) of patients achieved a rapid response in terms of PSA decline. Early PSA RR (≥50% at 15 days after start of AA) can provide clinically meaningful information and can be considered a surrogate of longer PFS and OS.

Diagnostic imaging to detect and evaluate response to therapy in bone metastases from prostate cancer: current modalities and new horizons

Different therapeutic options for the management of prostate cancer (PC) have been developed, and some are successful in providing crucial improvement in both survival and quality of life, especially in patients with metastatic castration-resistant PC. In this scenario, diverse combinations of radiopharmaceuticals (for targeting bone, cancer cells and receptors) and nuclear medicine modalities (e.g. bone scan, SPECT, SPECT/CT, PET and PET/CT) are now available for imaging bone metastases. Some radiopharmaceuticals are approved, currently available and used in the routine clinical setting, while others are not registered and are still under evaluation, and should therefore be considered experimental. On the other hand, radiologists have other tools, in addition to CT, that can better visualize bone localization and medullary involvement, such as multimodal MRI. In this review, the authors provide an overview of current management of advanced PC and discuss the choice of diagnostic modality for the detection of metastatic skeletal lesions in different phases of the disease. In addition to detection of bone metastases, the evaluation of response to therapy is another critical issue, since it remains one of the most important open questions that a multidisciplinary team faces when optimizing the management of PC. The authors emphasize the role of nuclear modalities that can presently be used in clinical practice, and also look at future perspectives based on relevant clinical data with novel radiopharmaceuticals.

Prostate-specific antigen kinetic profiles during androgen deprivation therapy as prognostic factors in castration-resistant prostate cancer

OBJECTIVE

To identify pretreatment prognostic factors for patients with castration-resistant prostate cancer (CRPC) undergoing docetaxel (DCT) chemotherapy.

MATERIALS AND METHODS

We retrospectively analyzed 102 patients with CRPC who underwent DCT chemotherapy (dosage: 60-75 mg/m(2)) from December 2001 to August 2013. The parameters evaluated as prognostic factors were as follows: age, body mass index, Gleason score, clinical TNM stage, prior radical prostatectomy, prior radiation therapy, performance status, presence of pain, laboratory results at the start of DCT, and prostate-specific antigen (PSA) kinetics during prior androgen deprivation therapy (ADT), including PSA level at the start of ADT (PSA-ADT), PSA half-time (PSAT1/2), time to nadir, PSA level at nadir (PSA-Nadir), duration of nadir, PSA doubling time (PSADT), and PSA level at the start of DCT (PSA-DCT). Univariate and multivariate analyses were performed to identify independent prognostic factors.

RESULTS

Median cancer-specific survival (CSS) duration following CRPC diagnosis was 28.0 months. In univariate analyses, performance status, serum albumin, serum creatinine, PSAT1/2, time to nadir, PSA-Nadir, duration of nadir, PSADT, and PSA-DCT showed a potential association with prognosis (P<0.001-0.077). Multivariate analyses of these parameters showed that performance status (hazard ratio [HR] = 0.046; P = 0.046), serum creatinine (HR = 3.028; P = 0.036), PSAT1/2 (HR = 0.172; P = 0.007), PSA-Nadir (HR = 4.884; P = 0.033), PSADT (HR = 0.148; P<0.001), and PSA-DCT (HR = 5.222; P = 0.004) remained independent predictors of CSS in CRPC.

CONCLUSIONS

PSA kinetic parameters measured during prior ADT are significant surrogate markers predicting CSS in patients undergoing DCT chemotherapy for CRPC.

PSA response rate as a surrogate marker for median overall survival in docetaxel-based first-line treatments for patients with metastatic castration-resistant prostate cancer: an analysis of 22 trials

The aim of this study was to determine the correlation between PSA response rate (PSA RR) and overall survival (OS) and identify PSA RR as a potential surrogate for OS, in docetaxel-based first-line treatments for castration-resistant prostate cancer (CRPC). Trials of first-line regimens with docetaxel for patients with metastatic CRCP published between 2004 and 2013 were identified, and data were evaluated statistically in order to investigate the correlation between PSA RR and OS. A total of 22 trials were identified and included in our analysis, for a total of 7,677 patients. In addition, we divided all the trails and arms of the randomized trials in two subgroups, the first one composed only of docetaxel (D) plus prednisone (P) regimens (standard therapy) and the second one composed of all D + other drug combinations (D combinations). Analysing all the trials and arms as a single unit, we found a statistically significant correlation between PSA RR and OS, with Spearman's rank correlation coefficient ρ = 0.50 (95% confidence interval (CI), 0.47 to 0.88) (P = 0.003). Also evaluating the standard therapy group, we found a statistically significant correlation between PSA RR and OS, with Spearman's ρ = 0.65 (95% CI, 0.38 to 0.70) (P = 0.02). However, when we assessed the D combination group, we found Spearman's rank correlation coefficient decreased (ρ = 0.42) (95% CI, 0.28 to 0.80) and resulted nonstatistically significant (P = 0.06). In conclusion, we found a statistically significant correlation between PSA RR and OS. The usage of PSA RR as a surrogate marker for OS in metastatic CRPC patients treated with D-based first-line regimens may be appropriate only in the D + P combination.

The retinoblastoma tumor suppressor modulates DNA repair and radioresponsiveness

PURPOSE

Perturbations in the retinoblastoma pathway are over-represented in advanced prostate cancer; retinoblastoma loss promotes bypass of first-line hormone therapy. Conversely, preliminary studies suggested that retinoblastoma-deficient tumors may become sensitized to a subset of DNA-damaging agents. Here, the molecular and in vivo consequence of retinoblastoma status was analyzed in models of clinical relevance.

EXPERIMENTAL DESIGN

Experimental work was performed with multiple isogenic prostate cancer cell lines (hormone sensitive: LNCaP and LAPC4 cells and hormone resistant C42, 22Rv1 cells; stable knockdown of retinoblastoma using shRNA). Multiple mechanisms were interrogated including cell cycle, apoptosis, and DNA damage repair. Transcriptome analysis was performed, validated, and mechanisms discerned. Cell survival was measured using clonogenic cell survival assay and in vivo analysis was performed in nude mice with human derived tumor xenografts.

RESULTS

Loss of retinoblastoma enhanced the radioresponsiveness of both hormone-sensitive and castrate-resistant prostate cancer. Hypersensitivity to ionizing radiation was not mediated by cell cycle or p53. Retinoblastoma loss led to alteration in DNA damage repair and activation of the NF-κB pathway and subsequent cellular apoptosis through PLK3. In vivo xenografts of retinoblastoma-deficient tumors exhibited diminished tumor mass, lower PSA kinetics, and decreased tumor growth after treatment with ionizing radiation (P < 0.05).

CONCLUSIONS

Loss of retinoblastoma confers increased radiosensitivity in prostate cancer. This hypersensitization was mediated by alterations in apoptotic signaling. Combined, these not only provide insight into the molecular consequence of retinoblastoma loss, but also credential retinoblastoma status as a putative biomarker for predicting response to radiotherapy.

A critical review of the analytical approaches for circulating tumor biomarker kinetics during treatment

Changes in serum tumor biomarkers may indicate treatment efficacy. Traditional tumor markers may soon be replaced by novel serum biomarkers, such as circulating tumor cells (CTCs) or circulating tumor nucleic acids. Given their promising predictive values, studies of their kinetics are warranted. Many methodologies meant to assess kinetics of traditional marker kinetics during anticancer treatment have been reported. Here, we review the methodologies, the advantages and the limitations of the analytical approaches reported in the literature. Strategies based on a single time point were first used (baseline value, normalization, nadir, threshold at a time t), followed by approaches based on two or more time points [half-life (HL), percentage decrease, time-to-events…]. Heterogeneities in methodologies and lack of consideration of inter- and intra-individual variability may account for the inconsistencies and the poor utility in routine. More recently, strategies based on a population kinetics approach and mathematical modeling have been reported. The identification of equations describing individual kinetic profiles of biomarkers may be an alternative strategy despite its complexity and higher number of necessary measurements. Validation studies are required. Efforts should be made to standardize biomarker kinetic analysis methodologies to ensure the optimized development of novel serum biomarkers and avoid the pitfalls of traditional markers.

A phase II study of GW786034 (pazopanib) with or without bicalutamide in patients with castration-resistant prostate cancer

INTRODUCTION

Pazopanib is an oral vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor. In this randomized, open label phase II study, pazopanib alone or in combination with bicalutamide was evaluated in patients with chemotherapy-naive castration-resistant prostate cancer (CRPC).

PATIENTS AND METHODS

Patients received either pazopanib 800 mg daily (arm A) or pazopanib 800 mg plus bicalutamide 50 mg daily (arm B). A 2-stage study design was used, and the primary endpoint was prostate-specific antigen (PSA) response rate (defined as a confirmed ≥ 50% decline from baseline).

RESULTS

A total of 23 patients (arm A, 10; arm B, 13) were accrued. The main grade 3+ toxicities were hypertension, fatigue, decreased lymphocytes, and increased alanine transaminase. Owing to significant toxicity, the protocol was amended after the first 11 patients and the pazopanib starting dose was reduced to 600 mg daily. In arm A, of 9 evaluable patients, there was 1 patient (11%) with a PSA response, 3 (33%) with stable PSA, and 5 (56%) with PSA progression; in arm B, of 12 evaluable patients, there were 2 patients (17%) with PSA responses, 6 (50%) with stable PSA, and 4 (33%) with PSA progression. Median progression-free survival was similar in both arms at 7.3 months (95% CI, 2.5 months to not reached). Long-term stable disease was seen in 4 patients who remained on treatment for 18 months (arm A), 26 months (arm A), 35 months (arm B), and 52 months (arm B).

CONCLUSION

In this unselected patient population, pazopanib either alone or in combination with bicalutamide failed to show sufficient activity to warrant further evaluation. However, 4 patients had long-term benefit, suggesting that targeting the VEGFR pathway may still be relevant in selected patients and emphasizing the need for improved predictive markers for patients with CRPC.

Metastatic castration resistant prostate cancer: current strategies of management in the Middle East

Although most patients with prostate cancer respond to initial androgen-deprivation therapy, progression to castration-resistant prostate cancer (CRPC) is almost inevitable. In 2004, the docetaxel/prednisone regimen was approved for the management of patients with metastatic CRPC, becoming the standard first-line therapy. Recent advances have also led to an unprecedented number of approved new drugs; thus, providing several treatment options for patients with metastatic CRPC. Five new drugs have received US Food and Drug Administration-approval between 2010 and 2012: sipuleucel-T, an immunotherapeutic agent; cabazitaxel, a novel microtubule inhibitor; abiraterone acetate, a new androgen biosynthesis inhibitor; enzalutamide, a novel androgen receptor inhibitor; and denosumab, a bone-targeting agent. Such drugs are either already marketed or about to be marketed in the Middle East. Data supporting the approval of each of these agents are described in this review, as are recent approaches to the treatment of metastatic CRPC.

Prostate-specific antigen changes as surrogate for overall survival in men with metastatic castration-resistant prostate cancer treated with second-line chemotherapy

PURPOSE

Prostate-specific antigen (PSA) kinetics, and more specifically a ≥ 30% decline in PSA within 3 months after initiation of first-line chemotherapy with docetaxel, are associated with improvement in overall survival (OS) in men with metastatic castration-resistant prostate cancer (mCRPC). The objective of this analysis was to evaluate post-treatment PSA kinetics as surrogates for OS in patients receiving second-line chemotherapy.

PATIENTS AND METHODS

Data from a phase III trial of patients with mCRPC randomly assigned to cabazitaxel plus prednisone (C + P) or mitoxantrone plus prednisone were used. PSA decline (≥ 30% and ≥ 50%), velocity, and rise within the first 3 months of treatment were evaluated as surrogates for OS. The Prentice criteria, proportion of treatment explained (PTE), and meta-analytic approaches were used as measures of surrogacy.

RESULTS

The observed hazard ratio (HR) for death for patients treated with C + P was 0.66 (95% CI, 0.55 to 0.79; P < .001). Furthermore, a ≥ 30% decline in PSA was a statistically significant predictor of OS (HR for death, 0.52; 95% CI, 0.43 to 0.64; P < .001). Adjusting for treatment effect, the HR for a ≥ 30% PSA decline was 0.50 (95% CI, 0.40 to 0.62; P < .001), but treatment remained statistically significant, thus failing the third Prentice criterion. The PTE for a ≥ 30% decline in PSA was 0.34 (95% CI, 0.11 to 0.56), indicating a lack of surrogacy for OS. The values of R(2) were < 1, suggesting that PSA decline was not surrogate for OS.

CONCLUSION

Surrogacy for any PSA-based end point could not be demonstrated in this analysis. Thus, the benefits of cabazitaxel in mediating a survival benefit are not fully captured by early PSA changes.

Prostate-specific antigen response rate of sequential chemotherapy in castration-resistant prostate cancer: the results of real life practice

Purpose:

Prostate-specific antigen (PSA) response rate (>50% PSA decline in pretreatment PSA following chemotherapy) carries a significant survival advantage in castration-resistant prostate cancer (CRPC). We compared PSA response rates in first-, second- and third-line chemotherapy after failure of previous chemotherapy according to chemotherapeutic agents.

Methods:

We retrospectively evaluated the oncological outcomes and PSA response rates of 384 patients with CRPC, who were treated with chemotherapy and had histologically proven adenocarcinoma of the prostate with failure after androgen ablation therapy between 1991 and 2012, at Asan Medical Center.

Results:

In 384 eligible patients, the median age was 67.5 years. The median pretreatment PSA and initial Gleason scores at baseline were 92.4 ng/mL (range, 2.0 to 6,370 ng/mL) and 9 (range, 6 to 10), respectively. The time from first diagnosis of prostate cancer to CRPC was 23 months (range, 1 to 164 months). As first-line chemotherapy, 245 patients (63.8%) received estramustine, 91 (23.7%) received docetaxel, and 39 (10.2%) received mitoxantrone. The PSA response rates were 39.6%, 51.6%, and 46.2%, respectively. Of 169 patients with second-line chemotherapy, estramustine was 15 (8.9%), docetaxel was 84 (49.7%), and mitoxantrone was 52 (30.8%). PSA response rates were 57.1%, 52%, and 28.0%, respectively. Of 81 patients with third-line chemotherapy, estramustine was 18 (22.2%), docetaxel was 16 (19.8%), and mitoxantrone was 28 (34.6%). The PSA response rates were 41.2%, 53.8%, and 11.1%, respectively. Declines in serum PSA levels of at least 50% occurred more frequently after treatment with docetaxel than with other chemo-agents regardless of second-and third-line chemotherapy. Even in third-line chemothrapy, docetaxel maintained the PSA response rate, whereas the PSA response rate of other agents, including mitoxantrone, decreased in patients in whom prior therapy failed.

Conclusions:

Docetacel was the most effective chemotherapeutic agent in second- and third-line trials of chemotherapy in Korean CRPC patients. Although docetaxel is not used as first-line chemotherapy, and new agents are not available for therapy in CRPC patients, we can consider docetaxel a second- or third-line chemotherapy in CRPC.

Role of immunotherapy in castration-resistant prostate cancer (CRPC)

Initial therapy for metastatic prostate cancer consists of androgenic suppression. However, this is only a palliative treatment with an effective duration that usually lasts 12-24 months. Historically, castration-resistant prostate cancer (CRPC) had been considered a chemoresistant tumour. In 2004, docetaxel received USA Food and Drug Administration approval as a first-line treatment for metastatic prostate cancer, after two independent phase III trials showed an increased survival benefit. Recently, five new drugs have shown increased survival in CRPC: sipuleucel-T (assymptomatic or minimally symptomatic), abiraterone acetate (before and after docetaxel), cabazitaxel (after docetaxel), MDV3100 (after docetaxel) and radium-223 (not suitable for docetaxel or after docetaxel). The identification of antigens in normal prostate tissue or prostate cancer that are recognised by immune effectors cells has resulted in several new studies based on immunotherapy. Prostate cancer disease provides a test system to determine the efficacy of vaccines for different reasons. This cancer is a tumour that grows relatively slowly. Recurrence is often diagnosed early (with many patients presenting only with biochemical progression), there is a biological marker that can predict prognosis and outcome (PSA doubling time), various specific antigens have been identified and characterised, and vaccines can be used with a good safety profile combined with anti-androgen therapy, chemotherapy, or radiotherapy. Here we provide a review of the main important immune treatments in CRPC.

Time trends in survival from cancer of unknown primary: small steps forward

BACKGROUND

Cancer of unknown primary (CUP) is a fatal cancer for which incidence trends have changed but detailed survival trends remain unexplored. These could point out successful diagnostic and therapeutic approaches. We investigate survival trends in CUP according to histology, locations of metastases and site-specific causes of death.

PATIENTS AND METHODS

A total of 20,523 CUP patients with nodal and extranodal metastases were identified from the Swedish Cancer Registry. Hazard ratios (HRs) were estimated, comparing three different time periods (1987-1993, 1994-2000 and 2001-2008) with respect to histological subtype, CUP location and the cause of death.

RESULTS

Survival for patients with CUP increased over the study period (HR=0.91 [95% confidence interval (CI): 0.78-0.84], p<0.001 for trend). Adenocarcinoma was the only histology associated with increased survival (0.78 [0.74-0.82], p<0.001 for trend). Survival was improved most clearly for CUP of the pelvis (0.55 [0.36-0.83]), peritoneum (0.58 [0.53-0.65]) and nervous system (0.46 [0.29-0.72]). Survival improved substantially in patients with ovarian (0.57 [0.46-0.70]), peritoneal (0.39 [0.24-0.65]) and biliary system cancers (0.67 [0.52-0.87]). Kaplan-Meier curves showed significant survival gains for all CUP and adenocarcinoma patients (p<0.001).

CONCLUSIONS

Over time, survival for patients with CUP increased for adenocarcinoma and for CUP of the pelvis, peritoneum and nervous system. Survival trends in CUP may be related to (1) similar trends in other common metastatic tumours, particularly pancreatic and hepatobiliary cancers, which are common 'hidden' primaries for CUP, (2) earlier detection and (3) advances in the management of metastatic cancers. The improvement in survival at specific locations suggests true therapeutic gains.

Primary androgen deprivation (AD) followed by active surveillance (AS) for newly diagnosed prostate cancer (PC): A retrospective study

BACKGROUND

Active surveillance (AS) is only recommended for Low-Risk prostate cancer (PC) with <34% biopsies positive. Studies describing the long-term outcome of men treated with androgen deprivation (AD) followed by AS are sparse.

MATERIALS AND METHODS

One hundred two men were treated with 12 months of AD in a medical oncology clinic specializing in PC between 1998 and 2007 and were followed for a median of 7.25 years. The biopsy complete response rate after AD and the incidence of disease progression while on subsequent AS was assessed. Baseline age, D'Amico risk category, PSA velocity, percentage core biopsies, and prostate volume were evaluated as potential predictors of disease progression.

RESULTS

D'Amico risk category for the 102 men: Low: n = 22, Intermediate: n = 30, and High: n = 50. Medians: Age 67.3, PSA 7.8, Gleason 3 + 4, >50% core biopsies positive, stage T1c. Seventy men had a clear biopsy and 31 of these had disease progression leading to additional treatment after a median of 52 months. D'Amico risk category of the 57 men with a positive biopsy after AD or disease progression on AS was: Low: n = 4 (18%), Intermediate: n = 16 (53%), and High: n = 37 (74%). No PC deaths occurred. Three men had clinical progression. In stepwise logistic regression analysis only higher D'Amico risk category and lower prostate volume predicted disease progression.

CONCLUSIONS

Despite a high prevalence of ≥50% core biopsies positive at baseline, AD induces durable remissions in most men with Low-Risk and about half with Intermediate-Risk PC.

The effect of baseline testosterone on the efficacy of degarelix and leuprolide: further insights from a 12-month, comparative, phase III study in prostate cancer patients

OBJECTIVE

To investigate the effects of baseline testosterone on testosterone control and prostate-specific antigen (PSA) suppression using data from a phase III trial (CS21) comparing degarelix and leuprolide in prostate cancer.

METHODS

In CS21, patients with histologically confirmed prostate cancer (all stages) were randomized to degarelix 240 mg for 1 month followed by monthly maintenance doses of 80 or 160 mg, or leuprolide 7.5 mg/month. Patients receiving leuprolide could receive antiandrogens for flare protection. Treatment effects on testosterone and PSA reduction, testosterone surge, and microsurges were investigated in 3 baseline testosterone subgroups: <3.5, 3.5-5.0, and >5.0 ng/mL. Data are presented for the groups receiving degarelix 240/80 mg (the approved dose) and leuprolide 7.5 mg.

RESULTS

Higher baseline testosterone delayed castration with both treatments. However, castrate testosterone levels and PSA suppression occurred more rapidly with degarelix irrespective of baseline testosterone. With leuprolide, the magnitude of testosterone surge and microsurges increased with increasing baseline testosterone. There was no overall correlation between baseline testosterone and initial PSA decrease in either treatment group, although PSA suppression tended to be slowest with leuprolide and fastest with degarelix in the high baseline testosterone subgroup.

CONCLUSION

Patients with high baseline testosterone may have greater risk of tumor stimulation (clinical flare) and mini-flares during gonadotrophin-releasing hormone agonist treatment and so the need for flare protection with antiandrogens in these patients is obvious, especially in metastatic disease. Although higher baseline testosterone delays castration, castrate testosterone and PSA suppression occur more rapidly with degarelix, irrespective of baseline testosterone, without the need for flare protection.

Clinical development of novel therapeutics for castration-resistant prostate cancer: historic challenges and recent successes

There have been more drugs approved by the US Food and Drug Administration for the treatment of castration-resistant prostate cancer in the past 3 years than in the prior 3 decades, with additional drugs on the verge of approval based on the results of recently reported randomized trials. While an improvement in the understanding of the pathogenesis of castration-resistant prostate cancer has undeniably accelerated the transition of novel approaches from "bench to bedside," the recent successes in the treatment of prostate cancer are also a result of the efforts of clinical investigators to redefine the framework in which drugs for castration-resistant disease are evaluated. This review will explore the shifting paradigm in drug development for castration-resistant prostate cancer over the past several decades, and highlight how new definitions, trial designs, and endpoints have facilitated the emergence of new therapies for this challenging disease.

Drivers for change in the management of prostate cancer - guidelines and new treatment techniques

Clinical practice guidelines and new treatment techniques are of particular importance for the effective management of prostate cancer. In Europe, the European Association of Urology guidelines offer a regularly updated evidence-based source of recommendations for the optimal treatment of prostate cancer. This review examines recent changes to guidelines highlighting developments in diagnosis, hormonal therapy in advanced and metastatic disease, bone protection, the definition of new terminology such as castrate-resistant prostate cancer, treatment of relapse after hormonal therapy, and cytotoxic therapy for castrate-resistant prostate cancer. The review also examines new surgical and radiotherapeutic developments in prostate cancer. This includes minimally invasive techniques such as robot-assisted radical prostatectomy, which is becoming the surgical gold standard for clinically localized disease in many countries. Other promising techniques reviewed include cryosurgical ablation of the prostate, laser-induced interstitial thermotherapy, vascular-targeted photodynamic therapy, and high-intensity focused ultrasound; with the exception of cryotherapy, these approaches are not currently recommended for routine clinical use. Finally, we will review the evidence supporting intensity modulated radiotherapy, an optimized high-precision form of three-dimensional conformal radiotherapy which aims to allow homogeneously increased radiation doses, without increased toxicity to healthy at-risk organs. Novel techniques such as proton beam or carbon ion radiotherapy, which may offer improved and more localized dose distribution with reduced damage to normal tissue, are also examined.

Phase II trial of simple oral therapy with capecitabine and cyclophosphamide in patients with metastatic breast cancer: SWOG S0430

BACKGROUND

Interest in oral agents for the treatment of metastatic breast cancer (MBC) has increased because many patients prefer oral to i.v. regimens. We evaluated a simple oral combination of capecitabine with cyclophosphamide (CPA) for MBC.

METHODS

The trial was designed to determine whether or not combination therapy would achieve a 42% response rate (RR) using the Response Evaluation Criteria in Solid Tumors (RECIST) in MBC. Patients with two or fewer prior chemotherapy regimens for MBC were eligible. Those with estrogen receptor-positive MBC had to have progressed on endocrine therapy. Patients had measurable disease or elevated mucin (MUC)-1 antigen and received CPA, 100 mg daily on days 1-14, and capecitabine, 1,500 mg twice daily on days 8-21, in 21-day cycles.

RESULTS

In 96 eligible patients, the median progression-free survival (PFS) interval was 5.9 months (95% confidence interval [CI], 3.7-8.0 months) and median overall survival (OS) time was 18.8 months (95% CI, 13.1-22.0 months). The RR was 36% (95% CI, 26%-48%) in 80 patients with measurable disease. The MUC-1 antigen RR was 33% (95% CI, 20%-48%), occurring in 15 of 46 patients with elevated MUC-1 antigen. Toxicity was mild, with no treatment-related deaths.

CONCLUSIONS

PFS, OS, and RR outcomes with capecitabine plus CPA compare favorably with those of capecitabine monotherapy and combination therapy with bevacizumab, sorafenib, or ixabepilone. The addition of these other agents to capecitabine does not improve OS time in MBC patients, and this single-arm study does not suggest that the addition of CPA to capecitabine has this potential in an unselected MBC population. When OS prolongation is the goal, clinicians should choose single-agent capecitabine.

MET and VEGF: synergistic targets in castration-resistant prostate cancer

Recent advances in the treatment of prostate cancer have resulted in improved outcomes, including longer survival, but new options are needed for treating patients with castration-resistant disease, particularly in the presence of bone metastasis. Data from preclinical models and clinical biomarker studies indicate that antiangiogenic agents should be a promising treatment for this patient population, and multiple agents in this class have demonstrated activity in early-stage clinical trials. Pivotal trials in prostate cancer with agents targeting vascular endothelial growth factor (VEGF) signalling have resulted in significant improvements in tumour response and progression-free survival. However, overall survival was not significantly improved. Recent preclinical studies suggest that the limited impact on overall survival may result from the development of evasive resistance after inhibition of angiogenesis, possibly through upregulation of MET (hepatocyte growth factor receptor) signalling. MET plays important roles in angiogenesis, tumour cell invasion and bone metastasis, all of which are key factors in castration-resistant prostate cancer. Inhibition of both the MET and VEGF pathways may improve the efficacy of angiogenesis inhibitors in prostate cancer.

Immunotherapy in prostate cancer: emerging strategies against a formidable foe

Recent clinical trials have shown therapeutic vaccines to be promising treatment modalities against prostate cancer. Unlike preventive vaccines that teach the immune system to fight off specific microorganisms, therapeutic vaccines stimulate the immune system to recognize and attack certain cancer-associated proteins. Additional strategies are being investigated that combine vaccines and standard therapeutics, including radiation, chemotherapy, targeted therapies, and hormonal therapy, to optimize the vaccines' effects. Recent vaccine late-phase clinical trials have reported evidence of clinical benefit while maintaining excellent quality of life. One such vaccine, sipuleucel-T, was recently FDA-approved for the treatment of metastatic prostate cancer. Another vaccine, PSA-TRICOM, is also showing promise in completed and ongoing randomized multicenter clinical trials in both early- and late-stage prostate cancer. Clinical results available to date indicate that immune-based therapies could play a significant role in the treatment of prostate and other malignancies.

End points and outcomes in castration-resistant prostate cancer: from clinical trials to clinical practice

New therapeutic approaches for castration-resistant prostate cancer (CRPC) introduce new treatment dilemmas: how best to sequence these options to maximally benefit patients, what tests to perform before and after treatment to assess disease status, and how to interpret the test results and use them to guide treatment. New and specific end points for different classes of drugs are needed to provide the information to guide these treatment decisions. In 2008, the Prostate Cancer Working Group 2 consensus criteria for early-phase clinical trials redefined clinical trial end points as first, to control, relieve, or eliminate disease manifestations present when treatment is started and second, to prevent or delay future disease manifestations. Disease manifestations include prostate-specific antigen (PSA), soft-tissue disease (nodes and/or viscera), bone disease (most common site of spread), and symptoms. Recent US Food and Drug Administration (FDA) approvals for CRPC therapies have been based on the prevent/delay end points that reflect unequivocal benefit to a patient: prolongation of life or reduction in skeletal-related events (SREs). For the practicing oncologist, the control/relieve/eliminate outcomes should serve primarily to inform the decision of whether to continue therapy. In this review, we consider individual end points such as PSA, imaging, and patient-reported outcomes in the context of the control/relieve/eliminate and prevent/delay framework. We address the time-to-event end points of metastasis prevention, SRE, time to progression, and overall survival in the context of regulatory approvals. We also discuss circulating tumor cells measured with the CellSearch assay, recently cleared by the FDA for monitoring CRPC.

A rapid PSA half-life following docetaxel chemotherapy is associated with improved survival in hormone refractory prostate cancer

INTRODUCTION

Docetaxel chemotherapy prolongs survival in metastatic hormone-refractory prostate cancer (mHRPC), but many patients fail to respond to this therapy and there is potential for serious toxicity. Patients differ in their percent prostate-specific antigen (PSA) decline and rate of PSA decline following treatment. We propose that patients who achieve a rapid rate of PSA decline, measured as a shorter PSA half-life (PSAHL), may experience a longer overall survival (OS) than those who achieve a slower rate of PSA decline.

METHODS

A chart review of patients treated with docetaxel for mHRPC in Alberta from January 2000 to May 2006 was performed. At 42 days (after 2 cycles) and 84 days (after 4 cycles) following chemotherapy, PSA response and PSAHL were determined. PSAHL could only be determined in patients with a PSA drop from baseline. Optimal PSAHL values for OS stratification were determined using the log-rank chi-square statistic. Survival analysis was carried out using Kaplan-Meier curves and regression analysis.

RESULTS

There were 154 patients who fulfilled the inclusion criteria. Using 42-day postdocetaxel data, no associations with OS could be demonstrated. Using 84-day postdocetaxel data, patients stratified by PSAHL demonstrated a significant difference in OS (15 months vs. 25 months) and this relationship remained following multivariate analysis (hazard ratio 0.08 [0.021-0.34]).

CONCLUSION

A more rapid rate of PSA decline (PSAHL <70 days) measured after 4 cycles of chemotherapy was associated with a longer OS. This result was independent of other known markers of survival and allowed for a greater survival differentiation than PSA response.

Serum miRNA-21: elevated levels in patients with metastatic hormone-refractory prostate cancer and potential predictive factor for the efficacy of docetaxel-based chemotherapy

BACKGROUND

miR-21 has been recognized as an "onco-microRNA" with the activity of negatively modulating the expression of tumor-suppressor genes. However, its role in prostate cancer (CaP) has not been well-documented. We designed this study to assess the potential function of serum miR-21 in the progression of CaP.

METHODS

Serum samples of 56 patients, including 20 patients with localized CaP, 20 with androgen-dependent prostate cancer (ADPC), 10 with hormone-refractory prostate cancer (HRPC), and 6 with benign prostatic hyperplasia (BPH), were collected for the measurement of miR-21. The 10 HRPC patients were administered docetaxel-based chemotherapy. Quantification of miR-21 was assayed by specific TaqMan qRT-PCR.

RESULTS

Serum miR-21 level was found to correlate to serum PSA level in patients with ADPC and HRPC, P = 0.012 and 0.049, respectively. There was no significant difference in serum miR-21 level between BPH, localized CaP and ADPC with PSA level <4 ng/ml. Higher levels of miR-21 were detected in patients with HRPC and ADPC with PSA level >4 ng/ml. Six of the 10 HRPC patients reached partial remission with a decreased PSA level of >50% after chemotherapy. Serum miR-21 levels were higher in patients who were resistant to docetaxel-based chemotherapy when compared to those sensitive to chemotherapy, P = 0.032.

CONCLUSIONS

Serum miR-21 levels are elevated in HRPC patients, especially in those resistant to docetaxel-based chemotherapy. It may be applicable as a marker to indicate the transformation to hormone refractory disease, and a potential predictor for the efficacy of docetaxel-based chemotherapy.

Evolving role of bone biomarkers in castration-resistant prostate cancer

The preferential metastasis of prostate cancer cells to bone disrupts the process of bone remodeling and results in lesions that cause significant pain and patient morbidity. Although prostate-specific antigen (PSA) is an established biomarker in prostate cancer, it provides only limited information relating to bone metastases and the treatment of metastatic bone disease with bisphosphonates or novel noncytotoxic targeted or biological agents that may provide clinical benefits without affecting PSA levels. As bone metastases develop, factors derived from bone metabolism are released into blood and urine, including N- and C-terminal peptide fragments of type 1 collagen and bone-specific alkaline phosphatase, which represent potentially useful biomarkers for monitoring metastatic bone disease. A number of clinical trials have investigated these bone biomarkers with respect to their diagnostic, prognostic, and predictive values. Results suggest that higher levels of bone biomarkers are associated with an increased risk of skeletal-related events and/or death. As a result of these findings, bone biomarkers are now being increasingly used as study end points, particularly in studies investigating novel agents with putative bone effects. Data from prospective clinical trials are needed to validate the use of bone biomarkers and to confirm that marker levels provide additional information beyond traditional methods of response evaluation for patients with metastatic prostate cancer.

Salvage chemotherapy for hormone-refractory prostate cancer: Association of Adriamycin and ifosfamide

Prostate carcinoma is the most common cancer in men. Hormone-resistance is the natural history of this metastatic disease and requires the use of docetaxel as the standard chemotherapy. At present, there is no approved second-line treatment. Here, we report a combination of treatment with Adriamycin and ifosfamide in a series of 7 relatively young patients with an average age of 57 years at the time of diagnosis. Chemotherapy was administered over 3 days with the following schedule: 20 mg/m(2) Adriamycin per day and 1-1.5 mg/m(2) ifosfamide per day, in association with Uromitexan. Treatment was repeated every 3 weeks. Three biological responses, one CT scan response, one bone scan response and two CT scan stabilizations, were obtained. Mean survival following this combination was 6.6 months, and over 26 months after first-line chemotherapy. Tolerance was good with the use of granulocyte-colony stimulating factors. Our observations clearly show that the use of this type of salvage therapy for relatively young patients in good physical condition should be further assessed in a clinical trial, particularly when different lines of chemotherapy are required.

Use of meta-analysis for the validation of surrogate endpoints and biomarkers in cancer trials

This article discusses statistical approaches to the validation of surrogate biomarkers and endpoints. One approach that has been successfully used in oncology consists of estimating associations at two levels: the association between the surrogate and the clinical endpoint, called the individual-level association, and the association between the effects of treatment on the surrogate and the clinical endpoint, called the trial-level association. This approach requires data to be available from multiple randomized trials, such as in a meta-analysis of trials based on individual patient data. The approach is illustrated using randomized trials of first-line treatments for advanced tumors of the colon, breast, ovary, and prostate. Data from several meta-analyses suggest that progression-free survival is an acceptable surrogate in advanced colorectal and ovarian cancer, but not in breast and prostate cancer.

PSA surge/flare-up in patients with castration-refractory prostate cancer during the initial phase of chemotherapy

BACKGROUND

Docetaxel-based chemotherapy has shown great promise for the treatment of CRPC and is considered the current standard of care. PSA is mainly used as marker to monitor the treatment response. Several articles were published reporting an initial PSA surge/flare-up after starting chemotherapy. The cause and the impact of this phenomenon are discussed controversially. The intention of this review is to define the significance of initial PSA surge/flare-up and to increase awareness to this phenomenon in the urological community.

MATERIALS AND METHODS

A comprehensive literature search was performed in different data bases using various key words. Relevant articles and references between 1999 and 2009 were reviewed and analyzed for data on the association between chemotherapy and initial PSA surge/flare.

RESULTS

The incidence of a PSA surge/flare-up ranges according to the reported studies between 7.6% and 13.6%. A PSA surge/flare-up was reported up to 404% from baseline PSA level followed by PSA response. The median duration of a PSA surge/flare-up is 2-3 weeks and can last up to 6-8 weeks. However, the occurrence of a PSA surge/flare-up did not impact outcome and survival negatively compared to patients with an immediate PSA response.

CONCLUSIONS

A considerable portion of CRPC patients experience an initial PSA surge/flare-up under systemic chemotherapy. The definitions used for PSA surge/flare-up differ slightly in the literature. This issue needs to be solved since it might impact defining treatment response. As a PSA surge/flare-up did not impact outcome and survival negatively, chemotherapy should be continued according to the literature addressing specifically the phenomenon of a PSA surge/flare-up for a minimum of 8 weeks or 3 rounds of a 3-weekly cycle chemotherapy regimen before further decisions are made about efficacy. However, Scher et al. recommended a 12-week period drug exposure based on their results on PSA progression-free survival and overall survival. This dilemma needs to be addressed in further data analysis in order to establish a general rule regarding when to stop chemotherapy. Physicians should be aware of this effect to avoid inadequate early discontinuation of chemotherapy. The underlying mechanisms of a PSA surge/flare-up are still elusive and need further clarification.

[Chemotherapy of hormonorefractory and hormonoresistant metastatic prostate cancer]

Since 2004 and the first improvement in overall survival in hormone refractory prostate cancer patients (HRPC) brought about by docetaxel, numerous phase II and III studies have been initiated. Considering the lack of efficacy in terms of overall survival, hormonal manipulations such as antiandrogen withdrawal, di-ethylstilbesterol or dexamethason are only indicated in "rising PSA" patients without clinical or radiological evidence of metastases. As first line treatment, the optimal chemotherapy regimen is docetaxel (75 mg/m(2) every 3 weeks) in association with prednisone (5 mg twice daily). Second line chemotherapies (mitoxantron, ixabepilon, docetaxel as a re-treatment, vinorelbin, doxorubicin...) provide modest results only in terms of progression-free survival. A phase III study of Straplatin has been prematurely interrupted. Targeted anti-angiogenic therapies have shown encouraging results in patients with metastatic localizations, and underline the need to identify target patients early through cellular markers (mTOR or EGFR overexpression) as well as the uselessness of PSA dosage to monitor efficacy. An ongoing phase III study is evaluating bevacizumab in association with docetaxel to improve overall survival. Both the Provenge vaccine and DN 101 (calcitriol) showed a survival gain of a few months in phase III studies. An ongoing EORTC phase II trial is evaluating antisense oligonucleotids in HRPC. Early introduction of docetaxel raises the issue of when to start chemotherapy as it may be relevant to initiate this treatment before the onset of hormone independence. GETUG 15 trial will try to answer this question.

Lycopene for advanced hormone refractory prostate cancer: a prospective, open phase II pilot study

PURPOSE

We investigated the influence of lycopene on the clinical and laboratory course in men with hormone refractory prostate cancer. To our knowledge this study represents the first time that subjective assessments of the course of therapy have been recorded.

MATERIAL AND METHODS

We performed a prospective, open phase II pilot study, in which patients with progressive hormone refractory prostate cancer were included. Lycopene supplementation (15 mg) was given daily for 6 months. Followup laboratory tests and clinical examinations were done monthly. Changes to analgesic use and quality of life (European Organisation for Research and Treatment of Cancer QLQ-C30) were measured. The study end point was a significant change in serum prostate specific antigen, clinical progression or the end of the 6-month observation period.

RESULTS

A total of 18 patients 64 to 85 years old (median age 73) were enrolled in the study during a 20-month period, of whom 17 could be analyzed. Five of the 17 patients (29%) withdrew from the study prematurely, including 4 of 5 because of prostate specific antigen progression and/or tumor associated complications, and 1 due to an allergic reaction to lycopene. Median prostate specific antigen doubled in 6 months from 42.7 ng/ml (range 13.8 to 521.6) in 17 patients to 96.4 ng/ml (range 13.5 to 1,240) in 12. Stable prostate specific antigen was observed in 5 of 17 patients (29%). None of the patients had a greater than 50% decrease in prostate specific antigen. Patients experienced a slight deterioration in mean health status at the end of the study compared to the outset. However, two-thirds of the patients experienced an improved or unchanged situation regardless of the clinical and biochemical course.

CONCLUSIONS

No clinically relevant benefits were shown for patients with advanced stages of the disease.

Dendritic-cell vaccination for prostate cancer

Vaccination with tumor antigen-loaded dendritic cells has been one of the most frequently applied immunotherapeutic strategies in prostate cancer. Immunological effects have been observed in a majority of patients, while clinical effects have been modest and transient. Advances in the understanding of the interplay between cancer and the immune system have generated new concepts in tumor immunology and immunotherapy that might aid in the improvement of vaccine effectiveness. The combination of immunotherapy with conventional treatment modalities and targeting of immunosuppressive mechanisms has demonstrated improved immunological and clinical results that warrant further investigation.