Prostate-specific Antigen Responders Research Articles

Assessing Response to PSMA Radiopharmaceutical Therapies with Single SPECT Imaging at 24 Hours After Injection.

Understanding the relationship between lesion-absorbed dose and tumor response in 177Lu-PSMA-617 radiopharmaceutical therapies (RPTs) remains complex. We aimed to investigate whether baseline lesion-absorbed dose can predict lesion-based responses and to explore the connection between lesion-absorbed dose and prostate-specific antigen (PSA) response. Methods: In this retrospective study, we evaluated 50 patients with 335 index lesions undergoing 177Lu-PSMA-617 RPT, who had dosimetry analysis performed on SPECT/CT at 24 h after cycles 1 and 2. First, we identified the index lesions for each patient and measured the lesion-based absorbed doses. Lesion-based response was calculated after cycle 2. Additionally, PSA50 response (a decline of 50% from baseline PSA) after cycle 2 was also calculated. The respective responses for mean and maximum absorbed doses and prostate-specific membrane antigen (PSMA) volumetric intensity product (VIP-PSMA) at cycles 1 and 2 were termed SPECTmean, SPECTmaximum, and SPECTVIP-PSMA, respectively. Results: Of the 50 patients reviewed, 46% achieved a PSA50 response after cycle 2. Of the 335 index lesions, 58% were osseous, 32% were lymph nodes, and 10% were soft-tissue metastatic lesions. The SPECT lesion-based responses were higher in PSA responders than in nonresponders (SPECTmean response of 46.8% ± 26.1% vs. 26.2% ± 24.5%, P = 0.007; SPECTmaximum response of 45% ± 25.1% vs. 19% ± 27.0%, P = 0.001; SPECTVIP-PSMA response of 49.2% ± 30.3% vs. 14% ± 34.7%, P = 0.0005). An association was observed between PSA response and SPECTVIP-PSMA response (R 2 = 0.40 and P < 0.0001). A limited relationship was found between baseline absorbed dose measured with a 24-h single time point and SPECT lesion-based response (R 2 = 0.05, P = 0.001, and R 2 = 0.03, P = 0.007, for mean and maximum absorbed doses, respectively). Conclusion: In this retrospective study, quantitative lesion-based response correlated with patient-level PSA response. We observed a limited relationship between baseline absorbed dose and lesion-based responses. Most of the variance in response remains unexplained solely by baseline absorbed dose. Establishment of a dose-response relationship in RPT with a single time point at 24 h presented some limitations.

Prediction of Resistance to 177Lu-PSMA Therapy by Assessment of Baseline Circulating Tumor DNA Biomarkers.

177Lu-PSMA-617 and 177Lu-PSMA I&T (collectively termed 177Lu-PSMA) are currently being used for the treatment of selected metastatic castration-resistant prostate cancer (mCRPC) patients with PSMA PET-positive disease, but biomarkers for these agents remain incompletely understood. Methods: Pretreatment circulating tumor DNA (ctDNA) samples were collected from 44 mCRPC patients receiving 177Lu-PSMA treatment. Prostate-specific antigen responders and nonresponders were assessed relative to the ctDNA findings at baseline. Results: The ctDNA findings indicated that nonresponders were more likely to have gene amplifications than were responders (75% vs. 39.2%, P = 0.03). In particular, amplifications in FGFR1 (25% vs. 0%, P = 0.01) and CCNE1 (31.2% vs. 0%, P = 0.001) were more likely to be present in nonresponders. CDK12 mutations were more likely to be present in nonresponders (25% vs. 3.6%, P = 0.05). Conclusion: Our analyses indicate that ctDNA assays may contain specific biomarkers predictive of response or resistance for 177Lu-PSMA-treated mCRPC patients. Additional confirmatory studies are required before clinicians can use these findings to make personalized treatment decisions.

Prevalence and Prognostic Implications of PSA Flares during Radium-223 Treatment among Men with Metastatic Castration Resistant Prostate Cancer.

Radium-223 (Ra233) prolongs the survival of men with symptomatic bone-predominant metastatic castration-resistant prostate cancer (mCRPC). However, prostate-specific antigen (PSA) response patterns are not closely associated with Ra223 therapy outcomes. Herein, we sought to analyze the impact of Ra223-induced PSA flares on patient outcome. Using a retrospective cohort study of Ra223 treatment in four Ontario/Canada cancer centres, we identified 134 patients grouped into sub-cohorts according to distinct PSA response patterns: (i) initial PSA flare followed by eventual PSA decline; (ii) PSA response (≥30% PSA decrease within 12 weeks of treatment); and (iii) PSA non-response. We analyzed patient characteristics and outcome measures, including overall survival (OS), using the Kaplan-Meier method and log-rank testing. PSA flares were observed in 27 (20.2%), PSA responses in 11 (8.2%), and PSA non-responses in 96 (71.6%) patients. Amongst PSA flare patients, 12 presented with post-flare PSA decreases below baseline and 15 with PSA decreases below the flare peak but above baseline. Although only six flare patients achieved ≥30% PSA decreases below baseline, the median OS of all flare patients (16.8 months, 95% CI 14.9-18.7) was comparable to that of PSA responders and non-responders (p = 0.349). In summary, around 20% of mCRPC patients experience Ra223-induced PSA flares, whose outcome is similar to that of men with or without PSA responses. Further studies are needed regarding suitable biochemical surrogate markers of response to Ra223.

Nadir Prostate-specific Antigen as an Independent Predictor of Survival Outcomes: A Post Hoc Analysis of the PROSPER Randomized Clinical Trial.

This post hoc analysis of PROSPER evaluated the relationship between depth of PSA decline and clinical outcomes in enzalutamide-treated men with nonmetastatic castration-resistant prostate cancer. PROSPER was an international, randomized, double-blind, placebo-controlled, phase 3 trial that demonstrated significantly improved metastasis-free survival and overall survival with androgen deprivation therapy plus enzalutamide vs placebo. A total of 905 enzalutamide-treated men were included in this post hoc analysis. Metastasis-free survival (primary endpoint) and overall survival (secondary endpoint) were evaluated for 4 mutually exclusive subgroups defined by PSA decline: <50% (reference); ≥50% to <90%; ≥90%, nadir ≥0.2 ng/mL; and ≥90%, nadir <0.2 ng/mL. Medians and 95% confidence intervals were determined using a 12-month landmark analysis; hazard ratios and P values were based on an unstratified Cox proportional analysis model. In enzalutamide-treated men, PSA declines of <50%, ≥50% to <90%, ≥90% with nadir ≥0.2 ng/mL, and ≥90% with nadir <0.2 ng/mL were associated with median metastasis-free survival in months (95% confidence intervals) of 22.1 (14.8-not reached), 34.2 (29.4-not reached), 36.6 (33.4-not reached), and not reached, respectively, and overall survival in months (95% confidence intervals) of 40.8 (31.7-44.9), 54.4 (49.0-67.0), 64.3 (63.4-not reached), and not reached, respectively. There was a statistically significant correlation between greater depth of PSA decline and improved clinical outcomes, suggesting a previously underappreciated relationship between changes in PSA levels and clinical outcomes in nonmetastatic castration-resistant prostate cancer.

Cortisol as biomarker for CYP17 inhibition in mCRPC patients treated with abiraterone acetate.

5035 Background: Abiraterone acetate is an effective metastatic castration resistant prostate cancer (mCRPC) treatment, however, there is a high variability in response. It inhibits CYP17, thereby preventing the production of androgens. Abiraterone trough concentrations (Cmin) &gt; 8.4 ng/mL have been associated with an increased progression free survival (PFS) (Eur J Cancer. 2017;72:54-61; Prostate Cancer Prostatic Dis. 2020;23(2):244-251). However, plasma levels do not directly provide information on the level of CYP17 inhibition. Ideally, testosterone levels should be measured, but these levels are below the detection limit of available assays. The synthesis of cortisol is also inhibited by abiraterone via CYP17 inhibition and might therefore be a biomarker for CYP17 inhibition. The objective of this study was to investigate if cortisol levels are related to abiraterone levels and to clinical response. Methods: An observational study was performed in mCRPC patients treated with abiraterone acetate. At the outpatient clinic, plasma samples were collected for pharmacokinetic (PK) monitoring at each hospital visit. Reference populations of healthy volunteers and mCRPC patients using enzalutamide were included to investigate the influence of mCRPC and abiraterone treatment on the circadian rhythm of cortisol. Abiraterone and cortisol levels were measured using validated liquid chromatography-mass spectrometry (LC-MS/MS) assays. Clinical (prostate specific antigen (PSA) independent) PFS and PSA response were evaluated. Results: In total, 117 mCRPC patients using abiraterone acetate, 100 mCRPC patients using enzalutamide and 12 healthy volunteers were included. A clear circadian rhythm of cortisol was described in healthy volunteers and unaffected in mCRPC patients using enzalutamide. Contrarily, a circadian rhythm of cortisol could not be identified in mCRPC patients using abiraterone acetate, due to continuous suppression throughout the day. Patients with an abiraterone Cmin &gt; 8.4 ng/mL (n = 77) had a median cortisol concentration of 1.03 ng/mL vs. 2.59 ng/mL in patients with an abiraterone Cmin ≤8.4 ng/mL (n = 40) (p = 0.020). The median cortisol concentration in PSA responders (n = 63) was 1.02 ng/mL vs. 2.59 ng/mL for PSA non responders (n = 54) (p = 0.037). Patients in the highest cortisol tertile ( &gt; 3.03 ng/mL) had a median PFS of 3.7 months (n = 39) vs. 13.8 months in patients with cortisol levels ≤3.03 ng/mL (n = 78) (p = 0.007). The median PFS was 16.3 months in patients with an abiraterone Cmin &gt; 8.4 ng/mL and cortisol concentration &lt; 3.03 ng/ml vs. 5.3 months in patients with an abiraterone Cmin &gt; 8.4 ng/mL and cortisol concentration &gt; 3.03 ng/ml (p = 0.02). Conclusions: This study demonstrates that cortisol levels are of additional value to abiraterone concentrations as a marker for abiraterone acetate efficacy. This might help be helpful to assess efficacy of abiraterone treatment.

Analysis of prevalence and prognostic implications of early versus delayed PSA declines during radium-223 (Ra223) treatment among men with metastatic castration-resistant prostate cancer (mCRPC).

117 Background: Ra233 is a well-tolerated, bone-seeking alpha emitter that prolongs the survival of men with mCRPC. Since there is a lack of validated biomarkers useful for disease monitoring during Ra223 therapy, we sought to characterize prostate-specific antigen (PSA) response patterns within a retrospective cohort study of real-world Ra223 treatment in four cancer centres across Ontario. Methods: Of 198 patients (pts) overall, 64 were not included due to incomplete data. The remaining 134 pts were grouped into (i) early PSA responders with a ≥30% PSA decrease (PSA30) within 12 weeks of treatment start, (ii) pts with an initial PSA flare followed by decreasing PSA, and (iii) non-responders. We analyzed the overall survival (OS) of these three cohorts using the Kaplan-Meier method and log-rank testing. Results: PSA30 responses were rare (n = 11; 8.2%), PSA flares were seen in 20.2% of pts (n = 27), but the majority of pts did not achieve a PSA response (n = 96; 71.7%). Of the pts identified as having a PSA flare, 11/27 (40.7%) presented with a post-flare PSA decrease below baseline, whereas in 16/27 (59.3%) the PSA decreased below the flare peak but not below baseline. 5/27 (18.5%) pts with a PSA flare achieved a PSA30. The median OS was not reached, 15.8 months and 14.7 months in responders, flare pts and non-responders, respectively (p &gt; 0.05). Similarly, one year OS was 90.9%, 67.7% and 63.9% in responders, flare pts and non-responders. Conclusions: PSA flares are seen in one fifth of men undergoing Ra223 therapy for mCRPC. Despite delayed PSA declines of varying degrees, the survival of PSA flare pts is comparable to men without any PSA decline.

Exposure-Response Assessment of Enzalutamide and Its Major Metabolites in a Real-World Cohort of Patients with Metastatic Castration-Resistant Prostate Cancer.

Enzalutamide is an oral agent for the treatment of metastatic castration-resistant prostate cancer (mCRPC); N-desmethyl enzalutamide is its active metabolite, which has clinically relevant anti-androgen capacities similar to enzalutamide, and carboxylic acid enzalutamide is an inactive metabolite. The aim of our study was to investigate the relationship between enzalutamide and N-desmethyl enzalutamide exposure and treatment response in a real-world cohort of patients with mCRPC. Retrospective, observational, pharmacokinetic study. Outpatient clinic at a tertiary cancer center in Amsterdam, the Netherlands. Sixty-five patients with mCRPC who were treated with enzalutamide 160mg daily and had at least one steady-state enzalutamide plasma concentration between May 2015 and June 2018; of these patients, 38 were prostate-specific antigen (PSA) responders and 27 were nonresponders. Plasma concentrations, determined by using liquid chromatography with tandem mass spectrometry (LC-MS/MS), were compared between PSA responders and nonresponders. Three clinical end points were evaluated separately in this study: PSA-independent progression-free survival (PFS), time to PSA progression (TTPP), and rate of PSA response (defined as ≥50% decrease in PSA level from baseline). Enzalutamide toxicity was defined as discontinuation due to adverse events, dose reductions due to adverse events, or temporary treatment interruption. For these analyses, plasma concentrations of enzalutamide and N-desmethyl enzalutamide were divided into quartiles. Mean±SD plasma concentrations in the 65 patients were as follows: enzalutamide 11.2±2.8μg/ml, N-desmethyl enzalutamide 9.9±2.9μg/ml, and carboxylic acid enzalutamide 6.1±4.3μg/ml. Plasma concentrations were not significantly different in the PSA responder versus nonresponder groups for enzalutamide (11.5 vs 10.6μg/ml, p=0.20), N-desmethyl enzalutamide (10.1 vs 9.6μg/ml, p=0.48), and carboxylic acid enzalutamide (6.5 vs 5.5μg/ml, p=0.34). Univariate and multivariate analyses did not show a relationship between plasma concentrations and PSA-independent PFS, TTPP, or toxicity. This study confirmed that enzalutamide plasma concentrations were not related to PSA-independent PFS, TTPP, or toxicity in patients with mCRPC, and demonstrated that plasma concentrations of its major metabolites were also not associated with treatment response. Based on these findings, there is no role for therapeutic drug monitoring of enzalutamide in patients with mCRPC in daily practice.

Association between urinary, bowel, and hormonal treatment-related symptoms and clinical outcomes in nonmetastatic castration-resistant prostate cancer (nmCRPC): PROSPER study.

233 Background: PROSPER data were analyzed to assess the relationship between time to worsening of urinary, bowel, and hormonal treatment-related symptoms and prostate-specific antigen (PSA) response, and the longitudinal association between symptom changes and metastasis-free survival (MFS). Methods: 1401 patients (pts) with nmCRPC at high metastasis risk were randomized 2:1 to enzalutamide (ENZA) or placebo. Urinary, bowel, and hormonal treatment-related symptoms were assessed with the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-PR25) at baseline (BL) and every 16 weeks. The association between time to first clinically meaningful symptom worsening and PSA response (≥50% decline from BL) was analyzed with stratified Cox regression using treatment as a covariate. Longitudinal symptom changes and MFS were evaluated in joint models using symptom scores as covariates, adjusted for treatment and clinical/demographic variables. The proportion of pts with improvement, no change, or deterioration at metastasis were analyzed by treatment group. Results: 723/1401 (52%) pts were PSA responders, including &gt;90% of ENZA pts. PSA responders were significantly less likely to develop urinary, bowel, and hormone treatment-related symptoms vs. non-responders (hazard ratio [HR] 0.58 [95% confidence interval 0.41, 0.81]; 0.59 [0.43, 0.80]; and 0.70 [0.51, 0.97], respectively). Every 9-point increase in urinary symptom score was associated with a 10% increased metastasis risk (HR 1.1 [1.05, 1.15]). Bowel and hormonal symptoms did not predict metastasis. Most pts reported no EORTC score changes at metastasis and maintained stable urinary/bowel symptoms, with no major observed symptom differences between treatment groups. Conclusions: ENZA delays metastasis and extends time to symptom worsening. A ≥50% PSA reduction from BL is associated with a reduction in risk for urinary, bowel, and hormonal treatment-related symptom worsening; changes in urinary symptoms from BL also predict metastases. Clinical trial information: NCT02003924 (PROSPER).

PSA response to cabazitaxel is associated with improved progression-free survival in metastatic castration-resistant prostate cancer: the non-interventional QoLiTime study.

To evaluate the association between prostate-specific antigen (PSA) response and progression-free and overall survival in men with metastatic castration-resistant prostate cancer (mCRPC) treated with cabazitaxel. Men with mCRPC receiving cabazitaxel (25mg/m2, every 3weeks) plus oral prednis(ol)one (10mg/day) were enrolled in the non-interventional, prospective QoLiTime study. Main outcome measures were progression-free survival and overall survival, in all patients and in those who showed a ≥50 or a ≥30% decrease in PSA relative to baseline after four cycles of cabazitaxel, as well as quality-of-life parameters. Of the 527 men (median age 72years), 266 received ≥4 cycles of cabazitaxel and had PSA response data. After four cycles, 34.6% of men achieved a PSA decrease ≥50% and 49.6% a decrease ≥30%. Median progression-free survival was 7.7 (95% CI 6.2, 9.5) months, and overall survival was 19.5 (95% CI 16.0, 30.9) months, corresponding to 1-year event rates of 39.4 and 78.8%, respectively. Median progression-free survival was longer in PSA responders versus non-responders (15.7 vs 5.5months at 50% cut-off; 15.7 vs 5.3months for 30% cut-off; both P<0.0001). Overall survival (50% cut-off) was 23.3months in responders and 16.0months in non-responders (P=0.068); corresponding data at the 30% cut-off are 21.7 and 16.0months (P=0.057). Overall, 55.4% of men experienced ≥1 adverse event, 59.6% of whom had a serious adverse event. PSA response after four cycles of cabazitaxel is associated with improved progression-free survival in men with mCRPC treated with cabazitaxel plus prednis(ol)one.

Treatment strategy for metastatic prostate cancer with extremely high PSA level: reconsidering the value of vintage therapy.

The prognostic significance of initial prostate-specific antigen (PSA) level for metastatic prostate cancer remains uncertain. We investigated the differences in prognosis and response to hormonal therapies of metastatic prostate cancer patients according to initial PSA levels. We analyzed 184 patients diagnosed with metastatic prostate cancer and divided them into three PSA level groups as follows: low (<100 ng ml−1), intermediate (100–999 ng ml−1), and high (≥1000 ng ml−1). All patients received androgen deprivation therapy (ADT) immediately. We investigated PSA progression-free survival (PFS) for first-line ADT and overall survival (OS) within each of the three groups. Furthermore, we analyzed response to antiandrogen withdrawal (AW) and alternative antiandrogen (AA) therapies after development of castration-resistant prostate cancer (CRPC). No significant differences in OS were observed among the three groups (P = 0.654). Patients with high PSA levels had significantly short PFS for first-line ADT (P = 0.037). Conversely, patients in the high PSA level group had significantly longer PFS when treated with AW than those in the low PSA level group (P = 0.047). Furthermore, patients with high PSA levels had significantly longer PFS when provided with AA therapy (P = 0.049). PSA responders to AW and AA therapies had significantly longer survival after CRPC development than nonresponders (P = 0.011 and P < 0.001, respectively). Thus, extremely high PSA level predicted favorable response to vintage sequential ADT and AW. The current data suggest a novel aspect of extremely high PSA value as a favorable prognostic marker after development of CRPC.

Efficacy and safety of enzalutamide (ENZA) in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with abiraterone acetate (Abi): A multicenter, single-arm, open-label study.

165 Background: This phase 4, multicenter, single-arm, open-label study evaluated the efficacy and safety of ENZA in patients (pts) with progressing mCRPC previously treated with Abi. Methods: All pts maintained castration therapy with luteinizing hormone-releasing hormone for the duration of the trial or had a bilateral orchiectomy. Pts were required to have progressive disease at study entry and ≥ 24 weeks of Abi treatment prior to receiving 160 mg/day ENZA. Prior chemotherapy was allowed. The primary end point was radiographic progression-free survival (rPFS). The secondary end points were overall survival (OS), prostate-specific antigen (PSA) response, and time to PSA progression. Safety was also assessed. Results: A total of215 pts were enrolled; 214 were treated with ENZA (median age, 73 years). The analysis was performed on data up to 48 weeks after the last pt started ENZA treatment. Median duration of prior Abi therapy was 54 weeks. The median duration of ENZA treatment was 5.7 months: 12 months in PSA responders and 4.6 months in non-PSA responders. 16% of pts received treatment for ≥ 1 year. The most common reason for treatment discontinuation was disease progression (65%). Median rPFS was 8.1 months (95% CI 6.1, 8.3). Median OS was not reached in the overall population and 75% of pts were alive 1 year after treatment initiation. PSA response (confirmed or unconfirmed) rate was 26.5% (48/181). The median time to PSA progression was 5.7 months (95% CI 5.6, 5.8). The overall objective response rate in pts with measurable disease at study entry was 12%. The most common treatment emergent adverse events (TEAEs) were fatigue (32%), decreased appetite (25%), asthenia (18%), back pain (17%), and arthralgia (16%). ENZA was primarily discontinued due to TEAEs in 8% of pts. No seizures were reported. Conclusions: In this study, ENZA remained active in pts with mCRPC previously treated with Abi. Median rPFS in pts with prior chemotherapy was consistent with previously reported data of ENZA in pts with mCRPC and prior chemotherapy/Abi therapy.Reported TEAEs were consistent with the known safety profile of ENZA. Clinical trial information: NCT02116582.

Cabazitaxel as second-line or third-line therapy in patients with metastatic castration-resistant prostate cancer.

To compare treatment outcomes in patients with metastatic castration-resistant prostate cancer treated with cabazitaxel (CA) as second-line or third-line therapy in the everyday clinical setting. Charts from 94 patients treated with CA as second-line (n=28) or third-line therapy (n=66) were evaluated. Common Terminology Criteria for Adverse Events were used to register grade 3-4 nonhematological toxicity during treatment with CA. Baseline metastatic castration-resistant prostate cancer-related prognostic factors, duration of therapy, and maximum prostate-specific antigen (PSA) percentage change were registered during treatment with CA and previous/subsequent novel androgen receptor targeting therapies. Progression-free survival (PFS) and overall survival (OS) were calculated using the Kaplan-Meier method. A median of 6 versus 5 treatment cycles was administered in patients treated with second-line and third-line CA (P=0.483). Events with grade 3-4 nonhematological toxicity were equally distributed in the two groups (32 vs. 35%, P=0.80). PSA responses were observed in 46 and 17% of patients treated with second-line and third-line CA (P=0.002). PFS (5.5 vs. 3.3 months, P=0.087, log rank) and OS (18.3 vs. 11.4 months, P=0.003, log rank) was longer in patients treated with second-line CA. OS measured from second-line abiraterone acetate/enzalutamide was similar (18.0 months) to second-line CA (P=0.883, log rank). Treatment-related toxicity was independent of CA being administered as second-line or third-line therapy. Although PFS and the frequency of PSA responders favored patients treated with second-line CA, one treatment sequence could not be considered superior to the other in this study.

Co-introduction of a steroid with docetaxel chemotherapy for metastatic castration-resistant prostate cancer affects PSA flare.

To investigate the potential relationship of steroid usage with prostate-specific antigen (PSA) flare as well as the prognostic impact of PSA flare, which is known to occur in 10-20% of patients with metastatic castration-resistant prostate cancer during docetaxel chemotherapy. This study included 71 patients with metastatic castration-resistant prostate cancer treated by docetaxel chemotherapy with co-introduction of a steroid. PSA flare was defined as a transient PSA increase followed by a PSA decrease. PSA flare was recognized in 7.0-23.9% of patients according to the definition used. Intriguingly, men with steroid intake before the initiation of docetaxel chemotherapy experienced significantly fewer PSA flares. The progression-free survival rate in men with PSA flare was equivalent to that of PSA responders, but significantly better than men with PSA failure. Our results suggest that de novo steroid co-introduction with docetaxel chemotherapy induces the PSA flare phenomenon. This novel finding may account for the mechanism of PSA flare as well as being valuable for distinguishing PSA elevation attributable to PSA flare from that attributable to PSA failure.

The efficacy of abiraterone acetate in treating Taiwanese chemo-refractory metastatic castration-resistant prostate cancer patients

ObjectiveTo evaluate the efficacy of abiraterone acetate in combination with prednisolone in Taiwanese men with metastatic castrate-resistant prostate cancer (mCRPC) who failed docetaxel-based chemotherapy. Materials and methodsIn this single-arm, open label study, 30 mCRPC patients with prostate specific antigen (PSA) progression after docetaxel chemotherapy were enrolled. All patients were treated with abiraterone acetate 1000 mg once daily and prednisolone 5 mg twice daily. The primary end-point was PSA response rate (defined as proportion of patients achieving a PSA decline of ≥50%). Secondary end-points were overall survival and time-to-PSA progression. ResultsAmong 28 patients who received one or more cycles of treatment, 15 (53.6%) men achieved PSA response [95% confidence interval (CI) 33.9–72.5]. The median time-to-PSA progression was 5.5 months (95% CI 3.1–7.9). The median interval from stopping abiraterone to death was 3.4 months (95% CI 0.1–21.0), and the median overall survival was 19.2 months (95% CI 13.0–25.4). The PSA responders had better overall survival compared with PSA nonresponders, in both univariate (log rank test, p = 0.007) and multivariate (Cox regression, p = 0.001; relative risk: 0.31; 95% CI: 0.12–0.76) analysis. Both a high Gleason score (≥8) and viscera involvement did not have an unfavorable response to abiraterone treatment. ConclusionA combination of abiraterone acetate and prednisolone can improve the overall survival in Taiwanese mCRPC patients who fail prior docetaxel chemotherapy.

Biomodulatory Treatment of Patients with Castration-Resistant Prostate Cancer: A Phase II Study of Imatinib with Pioglitazone, Etoricoxib, Dexamethasone and Low-Dose Treosulfan.

Therapeutic options for patients with castration-resistant prostate cancer (CRPC) remain limited. In a multicenter, Phase II study, 65 patients with histologically confirmed CRPC received a biomodulatory regimen during the six-month core study. Treatment comprised daily doses of imatinib mesylate, pioglitazone, etoricoxib, treosulfan and dexamethasone. The primary endpoint was prostate-specific antigen (PSA) response. Responders could enter an extension phase until disease progression or intolerable toxicity occurred. Mean PSA was 45.3 ng/mL at baseline, and 77 % of patients had a PSA doubling time <3 months. Of the 61 evaluable patients, 37 patients (60.6 %) responded or had stable disease and 23 of them (37.7 % of 61 patients) were PSA responders. Among the 23 responders mean PSA decreased from 278.9 ± 784.1 ng/mL at baseline to 8.8 ± 11.6 ng/mL at the final visit (week 24). The progression-free survival (PFS) was 467 days in the ITT population. Of the 947 adverse events, 57.6 % were suspected to be drug-related, 13.8 % led to dose adjustment or permanent discontinuation and 40.2 % required concomitant medication. This novel combination approach led to an impressive PSA response rate of 37.7 % in CRPC patients. The good PSA response and PFS rate combined with the manageable toxicity profile suggest an alternative treatment option.

Prostate-specific antigen decline during salvage radiation therapy following prostatectomy is associated with reduced biochemical failure

PurposeTo evaluate the prognostic value of prostate-specific antigen (PSA) decline during salvage radiation therapy (SRT) after prostatectomy. Methods and materialsWe reviewed an institutional database and identified all prostate cancer patients who were treated with SRT between the years 2003 and 2010, had at least 1 PSA measurement during their SRT course, and had no history of androgen deprivation therapy use prior to or during SRT. Disease characteristics, treatment information, and clinical outcomes data were tabulated for each patient. The PSA response during SRT was defined as a PSA decline of at least 0.2 ng/mL compared with the pretreatment PSA level. Bivariate and multivariate analyses using Cox proportional hazards modeling were performed to identify predictors of biochemical recurrence. ResultsSixty-four patients met eligibility criteria for this analysis. Median PSA before SRT was 0.63 ng/mL (interquartile range: 0.42-1.00). With a median follow-up time of 70 months after SRT, 5-year actuarial rates for biochemical control and metastasis-free survival were 61% (95% confidence interval [CI], 48%-75%) and 88% (95% CI, 79%-97%), respectively. The median number of PSA measurements per patient during SRT was 3 (range, 1-5). On bivariate analysis, PSA response during SRT and positive surgical margins were significantly associated with a decreased risk of biochemical recurrence (BR), with hazard ratios of 0.160 (95% CI, 0.059-0.431, P < .001) and 0.396 (95% CI, 0.168-0.935, P = .035). On multivariate analysis, PSA response during SRT and positive surgical margin were independent, favorable predictors for BR, with hazard ratios of 0.171 (95% CI, 0.063-0.463, P < .001) and 0.411 (95% CI, 0.177-0.956, P = .039). The 5-year biochemical control rate for PSA responders was 81%, compared with 37% for nonresponders (P < .001). ConclusionsProstate-specific antigen decline during SRT may be a valuable prognostic factor for subsequent clinical outcomes. Future studies should investigate the value of monitoring PSA during SRT and how PSA response may be used to personalize therapy.

Wechsel des LHRH-Analogons beim progredienten kastrationsresistenten Prostatakarzinom

Medicinal or surgical castration remains the treatment of choice in metastatic, hormone-naive prostate cancer; however, 2-12% of patients never reach the target serum levels for medicinal castration. We analyzed the therapeutic efficacy of triptorelin pamoate (TP) as salvage treatment due to its higher potency than endogenous luteinizing hormone-releasing hormone (LHRH). The amino acid sequence of TP is identical to that of endogenous LHRH except for position 6 where L-glycine is replaced by D-tryptophane rendering the synthetic moiety less susceptible to cleavage by proteolytic enzymes. In this study 36 patients with prostate-specific antigen (PSA) progression following first line complete androgen blockade and antiandrogen (ADT) withdrawal were retrospectively analyzed. All patients demonstrated no or minimal metastatic disease. The PSA levels, PSA doubling time (PSADT), PSA velocity (PSAV) and testosterone serum concentrations were correlated with the therapeutic response. All patients received TP at a dose of 11.5mg at 3-month intervals until documented progression. The mean patient age was 69.2 years (range 52-79 years), the mean PSA level was 23.4ng/ml (8.7-53.1ng/ml) and the mean PSADT was 9.2 months (2.9-15.4 months). Mean testosterone serum concentration was 38.67ng/dl (21-76ng/dl), the mean time between start of ADT and progression was 42.4 months (13-76 months) and the median time was 46.8 months (16-82 months). A PSA decrease of ≥50% was reached in 9 out of 36 (25%) patients, 3 out of 36 (13.9%) patients each demonstrated stable PSA levels and a prolongation of PSADT from 6.2 to 9.8 months. Mean progression-free survival (PFS) was 21.4 weeks (7-53 weeks). PSA-responders exhibited a PFS of 53.2 weeks (26-64 weeks) as compared to 28 weeks (17-35 weeks) in nonresponders. PSA responders demonstrated significantly higher testosterone serum concentrations of 48.3ng/dl (29-76ng/dl) as compared to nonresponders with 32.6ng/dl (21-62ng/dl, p=0.02). Mean follow-up was 31.4 months (27-39 months), overall survival was 80.5% and cancer-specific survival was 88.9%. Changing the LHRH analogue in castration-refractory prostate cancer (CRPC) with testosterone serum concentrations at or above the castration level results in a temporary PSA response. This treatment option might be included in the therapeutic algorithm of CRPC. Although the PFS is short it allows the continuation of a treatment option with minimal side effects in a mere palliative situation. The data underline the need for continuous monitoring of testosterone during treatment with LHRH analogues.

Change in Markers of Bone Metabolism with Chemotherapy for Advanced Prostate Cancer: Interleukin-6 Response Is a Potential Early Indicator of Response to Therapy

Men with androgen-independent prostate cancer (AIPC) frequently have bone metastasis. The effects of chemotherapy on markers of bone metabolism have not been well characterized. We conducted a prospective study of patients with AIPC randomized in the first cycle to receive either docetaxel/estramustine or zoledronic acid, a bisphosphonate, to inhibit osteoclastic activity. Here we report the effects of therapy on markers of bone metabolism in these patients following the first cycle of therapy. Serum levels of several indices of bone remodeling were evaluated using commercial enzyme-linked immunosorbent assays. Changes in markers of bone metabolism were compared in patients receiving initial chemotherapy versus bisphosphonate. There was no significant difference in median change in any of the measured bone markers in patients given zoledronic acid when compared to chemotherapy. When comparing responders to nonresponders, overall interleukin-6 (IL-6) decreased by 35% in prostate-specific antigen responders; whereas, IL-6 levels increased by 76% in nonresponders (p = 0.03). Elevated IL-6 levels and reductions in IL-6 levels early in treatment may reflect ultimate clinical response to docetaxel-based regimens.

Prostate‐specific antigen flare phenomenon with docetaxel‐based chemotherapy in patients with androgen‐independent prostate cancer

To evaluate the prostate-specific antigen (PSA) 'flare' phenomenon in patients with androgen-independent prostate cancer (AIPC) treated with docetaxel, as flare is a known effect of androgen-deprivation therapy in hormone-dependent prostate cancer. The charts of 56 patients who received docetaxel-based chemotherapy in three different centres from August 1999 to August 2007 were reviewed retrospectively. The biochemical response was characterized according to the Bubley criteria. There was an immediate PSA response (PSA decline >or= 50%) in 23 (41%) patients, PSA stabilization (PSA decline < 50%) in 16 (29%) and PSA progression in nine (16%). There was also a fourth response, i.e. PSA flare, defined as an increase in PSA level with no symptomatic progression, after starting docetaxel-based chemotherapy administered every 3 weeks. Eight (14%) patients with PSA flare were identified; all had osseous disease and five had additional soft-tissue disease. The PSA flare lasted a median (range) of 21 (21-42) days and it spread over a median of 1 (1-2) cycles. The temporary PSA surge exceeded baseline values by a median (range) of 61.5 (12-404)%. There was a subsequent PSA response in six of the eight patients and PSA stabilized in the remaining two. Patients with flare received a median of 8.5 (5-12) treatment cycles, vs a median of 8 (2-12) in the immediate PSA response group (P = 0.103, Student's t-test). The Response Evaluation Criteria in Solid Tumors criteria evaluation showed one patient with a partial response and six with stable disease. The median survival of patients with PSA flare was 12.5 months, while that of the immediate PSA responders was 20.1 months (not statistically significant, P = 0.168, log-rank test). Of patients with AIPC, 14% had an initial PSA flare after starting docetaxel-based chemotherapy. The occurrence of PSA flare had no effect on treatment duration or outcome. With lack of clinical progression, docetaxel-based chemotherapy should be administered for at least two 3-week cycles before further decisions are made about efficacy.

Long-term outcome of patients treated with docetaxel for hormone-dependent prostate-specific antigen (PSA) progression after local therapy for prostate cancer

16030 Background: Mechanisms of chemotherapy resistance increase as cancer progresses, and a treatment approach that targets prostate tumors early, before hormonal therapy, may result in an improved outcome. A long-term outcomes analysis of our prior published study (treating patients for up to 8 months of docetaxel) was conducted to determine if the natural history of patients with PSA progression was altered by docetaxel. Methods: Twenty patients treated on our prior study were assessed for long-term follow up at a median of 9.4 years. All patients were followed until PSA progression (increase of 2 ng/mL over nadir) without the introduction of androgen ablation therapy, but may have received androgen ablation prior to radiographic progression (i.e., metastatic disease). One patient was excluded from the current analysis due to stage D1 disease pre-trial. Time to PSA progression, time to radiographic progression, and mortality were assessed. Comparisons were made between responders and non-responders to docetaxel (responders = PSA decrease ≥ 50%). Kaplan-Meier curves were constructed for the time to radiographic progression and mortality data. Results: Nineteen patients were treated on the original study with a mean time to PSA progression after local therapy of 3.3 years and a mean pre-trial PSA doubling time of 186 days. On docetaxel therapy, 8 (42%) of 19 patients demonstrated a decrease in PSA by ≥ 50% for at least 4 weeks. The median time to PSA progression after trial end was 57.5 vs. 20.0 days among PSA responders and non-responders respectively. The median time to radiographic progression from diagnosis of prostate cancer was 56.5 (95% CI: 27.7 to 99.8) vs. 45.3 months (95% CI: 40.3 to 82.5) among PSA responders and non-responders respectively. There were 4 deaths in the follow up period. Conclusions: Although treatment with docetaxel did not appear to alter overall progression in this small study, the trend towards longer time to disease progression in PSA responders suggests activity, and warrants larger studies of chemotherapy in this patient population. No significant financial relationships to disclose.