The effect of prior docetaxel (DOC) treatment on efficacy and safety of apalutamide (APA) plus androgen deprivation therapy (ADT) in patients (pts) with metastatic castration-sensitive prostate cancer (mCSPC) from TITAN

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Background: Addition of androgen receptor signaling inhibitors to ADT + DOC has been shown to improve clinical outcomes in pts with mCSPC. TITAN, a placebo-controlled phase 3 study, showed that APA + ADT improved overall survival (OS) and other clinical outcomes in mCSPC (Chi, J Clin Oncol 2021). This post hoc analysis of TITAN evaluated outcomes in pts who had received DOC prior to treatment with APA + ADT versus those who did not. Methods: In TITAN, 1052 pts were randomized 1:1 to APA (240 mg QD) or placebo added to ongoing ADT. We assessed radiographic progression-free survival (rPFS), OS, and time to prostate-specific antigen (PSA) progression in pts receiving DOC and ADT prior to adding APA vs those receiving only ADT plus APA. Outcomes by prior DOC were also assessed in pts with high- or low-volume disease at randomization (baseline [BL]) per adapted CHAARTED criteria, or those with matched BL characteristics. A Cox proportional hazards model was used to derive hazard ratios (HRs) and p values. rPFS was assessed using the first interim analysis cutoff (23 mo median follow-up); OS and time to PSA progression were assessed using the final analysis cutoff (44 mo median follow-up). Results: A total of 58/525 (11%) pts from the APA + ADT group had received DOC prior to randomization: 76% (n = 44) had high-volume disease, 62% (n = 36) had bone-only metastases, 16% (n = 9) had visceral metastases, and 59% (n = 34) had > 10 bone lesions. In the overall APA-treated population and in the subset of pts with high-volume disease, OS, rPFS, and time to PSA progression were similar in those who received prior DOC and those who did not (Table). Pts with low-volume disease also had similar results, although the number of pts was small. Clinical outcomes in pts with matched BL characteristics (including PSA and time from initial diagnosis to randomization, among others) were similar regardless of prior use of DOC (Table). The safety profile of APA was not substantially different between pts with or without prior DOC. Limitations of this analysis include lack of data on tumor volume and other disease characteristics at the initiation of prior DOC treatment; interpretation was based on small number of pts with prior DOC (only 11% of TITAN pts), most notably in the rPFS analysis. Conclusions: Prior use of DOC in pts with mCSPC did not further improve clinical benefits of APA + ADT in TITAN. Clinical trial information: NCT02489318. [Table: see text]

Guidelines for Management of Treatment-Emergent Adverse Events During Rucaparib Treatment of Patients with Metastatic Castration-Resistant Prostate Cancer

Purpose

The US Food and Drug Administration has recently granted accelerated approval of the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib as treatment for men with metastatic castration-resistant prostate cancer (mCRPC) associated with a deleterious germline or somatic BRCA1 or BRCA2 (BRCA) alteration. As the safety profile of this new addition to the mCRPC treatment landscape may be unfamiliar to clinicians and patients, we summarize the data from the literature and provide practical guidelines for the management of treatment-emergent adverse events (TEAEs) that may occur during rucaparib treatment.

Materials and Methods

Safety data were identified from PubMed and congress publications of trials involving men with mCRPC treated with oral rucaparib monotherapy (600 mg twice daily). Management guidelines for TEAEs were developed based on trial protocols, prescribing information, oncology association guidance, and the authors’ clinical experience.

Results

In clinical trials of men with mCRPC who received rucaparib (n = 193), TEAEs observed were consistent with that of other PARP inhibitors. The most frequent any-grade TEAEs included gastrointestinal events, asthenia/fatigue, anemia, increased alanine/aspartate aminotransferase, rash, and thrombocytopenia; the most frequent grade ≥3 TEAE was anemia. The majority of TEAEs were self-limiting and did not require treatment modification or interruption. Here, we provide recommendations on management of the most common TEAEs reported with rucaparib as well as other TEAEs of interest.

Conclusion

Rucaparib’s recent approval for treatment of BRCA-mutant mCRPC is practice changing. Proper management of TEAEs will allow maximum treatment benefit for patients receiving rucaparib.

Concomitant use of oral anticoagulants in patients with advanced prostate cancer receiving apalutamide: A post-hoc analysis of TITAN and SPARTAN studies

Apalutamide, an androgen receptor signaling inhibitor, in combination with androgen-deprivation therapy (ADT), is approved for treatment of patients with nonmetastatic castration-resistant prostate cancer and metastatic castration-sensitive prostate cancer, based on the data from the phase 3 SPARTAN and TITAN studies respectively. Apalutamide is an inducer of cytochrome P450 enzymes and P-glycoprotein, which are involved in the metabolism of oral anticoagulants (OACs) and may thus have potential drug-drug interactions when co-administered with OACs. Concomitant use of certain OACs such as apixaban, rivaroxaban, edoxaban, dabigatran, and warfarin was allowed in the SPARTAN and TITAN studies. A post-hoc analysis was conducted to evaluate the incidence of treatment-emergent thrombotic and embolic adverse events (AEs) in patients receiving concomitant OACs with apalutamide + ADT or placebo + ADT in both the studies. Anticoagulants were identified by WHO Drug Anatomical Therapeutic Chemical level 4 classifications. Thrombotic and embolic AEs were coded using the Medical Dictionary for Regulatory Activities Version 22.1. Data were analyzed from patients receiving concurrent OACs among all treated patients in SPARTAN (apalutamide + ADT: 95/803 [11.8%]; placebo + ADT: 48/398 [12.1%]) and TITAN (apalutamide + ADT: 31/524 [5.9%]; placebo + ADT: 28/527 [5.3%]). No consequential differences were observed in the occurrence of thrombotic and embolic events between apalutamide + ADT and placebo + ADT groups receiving concomitant OACs in SPARTAN (11.6% vs 12.5%) or TITAN (19.4% vs 21.4%). Grade 3/4 thrombotic and embolic AEs observed in patients receiving concomitant OACs with apalutamide + ADT or placebo + ADT were 6 (6.3%) vs 5 (10.4%) in SPARTAN and 3 (9.7%) vs 1 (3.6%) in TITAN. This analysis suggests that when necessary, concomitant OACs can be used with apalutamide with appropriate monitoring.

Health-related quality of life (HRQoL) and patient-reported outcomes at final analysis of the TITAN study of apalutamide (APA) versus placebo (PBO) in patients (pts) with metastatic castration-sensitive prostate cancer (mCSPC) receiving androgen deprivation therapy (ADT)

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Background: The phase 3 TITAN study evaluated APA vs PBO in pts with mCSPC receiving ADT. At primary analysis with 22.7 mo median follow-up, APA significantly improved overall survival (OS) and radiographic progression-free survival vs PBO (Chi NEJM 2019) while preserving HRQoL (Agarwal Lancet Oncol 2019). The study was unblinded; pts on PBO were allowed to cross over to APA. At final analysis with 44 mo median follow-up, APA significantly improved OS vs PBO, reducing risk of death by 35% despite crossover (Chi ASCO GU 2021). We evaluated HRQoL and treatment bother at final analysis. Methods: mCSPC pts (N = 1052) were randomized 1:1 to APA (240 mg QD; n = 525) or PBO (n = 527). All pts received ADT. Patient-reported outcomes were assessed using Brief Pain Inventory-Short Form (BPI-SF) and Functional Assessment of Cancer Therapy-Prostate (FACT-P). BPI was completed for 7d consecutively (Days -6 to 1 of each 28-d cycle [C]) through end of treatment (EOT). FACT-P was completed at baseline (BL), C2-C7, then every other C through EOT. Mean scores were reported by treatment group and over time. Time to deterioration on BPI and FACT-P scores was calculated by Kaplan-Meier methods and compared between groups by fitting proportional hazards regression models. Results: Of eligible pts per C, > 62% completed BPI through C32 and > 50% completed FACT-P through C31. Pts were relatively asymptomatic with good BL HRQoL: on 0-10 worst pain severity scale (BPI), median scores were 1.1 (APA) and 1.0 (PBO); on 0-156 HRQoL scale (FACT-P total; higher score = better HRQoL), median scores were 113.0 (APA) and 113.3 (PBO). Low BL BPI scores remained stable over time in both groups. On average, favorable BL FACT-P scores did not notably worsen over time in APA or PBO groups. There were no significant differences between groups in median time to deterioration in any BPI or FACT-P scores (Table). At each C at least 86% (APA) and 85% (PBO) of pts were either “not at all” or “a little bit” bothered by side effects. At BL, 76% (APA) and 72% (PBO) had favorable energy levels (reporting lack of energy “not at all” or “a little bit”). Energy levels remained stable or improved at each C for > 78% (APA) and > 71% (PBO) of pts. Conclusions: In the final analysis of TITAN, survival benefit with addition of APA to ADT was achieved without significant patient-reported side effect burden or reduced HRQoL compared with PBO in pts with mCSPC. Clinical trial information: NCT02489318. [Table: see text]

Apalutamide in Patients With Metastatic Castration-Sensitive Prostate Cancer: Final Survival Analysis of the Randomized, Double-Blind, Phase III TITAN Study

PURPOSE

The first interim analysis of the phase III, randomized, placebo-controlled TITAN study showed that apalutamide significantly improved overall survival (OS) and radiographic progression-free survival in patients with metastatic castration-sensitive prostate cancer (mCSPC) receiving ongoing androgen deprivation therapy (ADT). Herein, we report final efficacy and safety results after unblinding and placebo-to-apalutamide crossover.

METHODS

Patients with mCSPC (N = 1,052) were randomly assigned 1:1 to receive apalutamide (240 mg QD) or placebo plus ADT. After unblinding in January 2019, placebo-treated patients were allowed to receive apalutamide. Efficacy end points were updated using the Kaplan-Meier method and Cox proportional-hazards model without formal statistical retesting and adjustment for multiplicity. Change from baseline in Functional Assessment of Cancer Therapy-Prostate total score was assessed.

RESULTS

With a median follow-up of 44.0 months, 405 OS events had occurred and 208 placebo-treated patients (39.5%) had crossed over to apalutamide. The median treatment duration was 39.3 (apalutamide), 20.2 (placebo), and 15.4 months (crossover). Compared with placebo, apalutamide plus ADT significantly reduced the risk of death by 35% (median OS not reached v 52.2 months; hazard ratio, 0.65; 95% CI, 0.53 to 0.79; P < .0001) and by 48% after adjustment for crossover (hazard ratio, 0.52; 95% CI, 0.42 to 0.64; P < .0001). Apalutamide plus ADT delayed second progression-free survival and castration resistance (P < .0001 for both). Health-related quality of life, per total Functional Assessment of Cancer Therapy-Prostate, in both groups was maintained through the study. Safety was consistent with previous reports.

CONCLUSION

The final analysis of TITAN confirmed that, despite crossover, apalutamide plus ADT improved OS, delayed castration resistance, maintained health-related quality of life, and had a consistent safety profile in a broad population of patients with mCSPC.

Final analysis results from TITAN: A phase III study of apalutamide (APA) versus placebo (PBO) in patients (pts) with metastatic castration-sensitive prostate cancer (mCSPC) receiving androgen deprivation therapy (ADT)

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Background: TITAN evaluated APA or PBO added to ADT in pts with mCSPC. Pts with high- and low-volume disease, prior docetaxel, prior treatment for localized disease, and prior ADT (≤ 6 mos) were eligible. At the first interim analysis, with 22.7 mos median follow-up, APA significantly improved dual primary end points of overall survival (OS) (hazard ratio [HR] 0.67) and radiographic progression-free survival (rPFS) (HR 0.48) compared with PBO (Chi et al. NEJM. 2019). At that time, OS analysis was first planned interim while rPFS was final. TITAN was unblinded, allowing pts without progression who were still receiving PBO to cross over to APA. Herein, we report the final analysis of efficacy and safety results from TITAN. Methods: 1052 mCSPC pts were randomized 1:1 to receive APA (240 mg QD) or PBO plus ADT. Time-to-event end points were analyzed by Kaplan-Meier method and Cox proportional hazards model. A preplanned sensitivity analysis for OS, accounting for crossover using inverse probability censoring weighted (IPCW) log-rank test, was conducted. No formal statistical retesting was performed; nominal p values were reported without multiplicity adjustment. Change from baseline in Functional Assessment of Cancer Therapy-Prostate (FACT-P) total score was assessed using a mixed-effect repeated-measures model. Results: With 44 mos median follow-up, 405 OS events had occurred. After unblinding, 208 PBO pts (39.5%) crossed over to APA. Median treatment duration was 39.3 mos for the APA group, 20.2 mos for the entire PBO group, and 15.4 mos for the PBO→APA crossover group. OS was superior in the APA group compared with the PBO group despite crossover (Table). 48-mo survival rates were 65% (APA) vs 52% (PBO). Other end points also favored APA vs PBO (Table). Health-related quality of life (HRQoL), per total FACT-P, was maintained in the APA group through the study and was not different from the PBO group. Safety was consistent with previous reports. Conclusions: With close to 4 yrs of follow-up, the final analysis of TITAN demonstrated that in a broad population of pts with mCSPC, APA plus ADT provides an improvement in OS with a 35% reduction in risk of death, which increased to 48% reduction after adjusting for pts who crossed over from PBO to APA. In addition, there was consistent benefit with APA in other end points, including delaying castration resistance, and HRQoL continued to be maintained with an acceptable safety profile. Clinical trial information: NCT02489318. [Table: see text]

Apalutamide for Metastatic, Castration-Sensitive Prostate Cancer

BACKGROUND

Apalutamide is an inhibitor of the ligand-binding domain of the androgen receptor. Whether the addition of apalutamide to androgen-deprivation therapy (ADT) would prolong radiographic progression-free survival and overall survival as compared with placebo plus ADT among patients with metastatic, castration-sensitive prostate cancer has not been determined.

METHODS

In this double-blind, phase 3 trial, we randomly assigned patients with metastatic, castration-sensitive prostate cancer to receive apalutamide (240 mg per day) or placebo, added to ADT. Previous treatment for localized disease and previous docetaxel therapy were allowed. The primary end points were radiographic progression-free survival and overall survival.

RESULTS

A total of 525 patients were assigned to receive apalutamide plus ADT and 527 to receive placebo plus ADT. The median age was 68 years. A total of 16.4% of the patients had undergone prostatectomy or received radiotherapy for localized disease, and 10.7% had received previous docetaxel therapy; 62.7% had high-volume disease, and 37.3% had low-volume disease. At the first interim analysis, with a median of 22.7 months of follow-up, the percentage of patients with radiographic progression-free survival at 24 months was 68.2% in the apalutamide group and 47.5% in the placebo group (hazard ratio for radiographic progression or death, 0.48; 95% confidence interval [CI], 0.39 to 0.60; P<0.001). Overall survival at 24 months was also greater with apalutamide than with placebo (82.4% in the apalutamide group vs. 73.5% in the placebo group; hazard ratio for death, 0.67; 95% CI, 0.51 to 0.89; P = 0.005). The frequency of grade 3 or 4 adverse events was 42.2% in the apalutamide group and 40.8% in the placebo group; rash was more common in the apalutamide group.

CONCLUSIONS

In this trial involving patients with metastatic, castration-sensitive prostate cancer, overall survival and radiographic progression-free survival were significantly longer with the addition of apalutamide to ADT than with placebo plus ADT, and the side-effect profile did not differ substantially between the two groups. (Funded by Janssen Research and Development; TITAN ClinicalTrials.gov number, NCT02489318.).

Multicenter extension and switch study evaluating the safety of long-term treatment with abiraterone acetate fine particle formulation (AAFP) in patients with metastatic castration-resistant prostate cancer (mCRPC): The STAAR-E study

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Background: The STAAR-study results showed novel AAFP 500 mg is therapeutically equivalent to originator abiraterone acetate (OAA) 1000 mg in men with mCRPC (Stein et al. Urologic Oncol). This STAAR-extension study evaluates the safety of ≤ 1 year of additional AAFP treatment in men with mCRPC. Methods: Patients were enrolled in the extension if they had: 1) mCRPC; 2) successfully completed 84 days of treatment with either AAFP + methylprednisolone (MP) or OAA + prednisone (PDN) in the STAAR-study; and 3) received their last dose of STAAR-study treatment < 45 days of starting this extension study. All patients continued or switched to AAFP 500 mg QD + 4 mg MP BID. Serum testosterone and PSA levels are measured at 6 and 12 months. Safety evaluations include adverse event (AE) incidence, clinical laboratory test results, and vital signs. Results: 20 patients were enrolled in the ongoing study (11 were switched to AAFP from OAA and 9 continued on AAFP). Median age is 76.5 years, and median AAFP treatment duration (STAAR + STAAR-E) is 178 days as of 8/16/17. Ten patients have been treated with AAFP > 9 months; 3 of these for > 1 year. Three patients discontinued due to progressive disease (n=1), fatigue (n=1), and a fall (non-AAFP related) resulting in death (n=1). No adverse events related to liver enzyme or bilirubin increases have been reported (Table). Conclusions: In this extension study in men with mCRPC, the safety profile of AAFP, regardless of prior treatment with OAA or AAFP, is consistent with that of OAA reported in the literature. Based on these results, longer-term treatment with AAFP + MP has acceptable safety, and patients on OAA + PDN treatment can switch to AAFP + MP successfully. Clinical trial information: NCT02962284. [Table: see text]

First interim results of the Radium-223 (Ra-223) reassure observational study in metastatic castration-resistant prostate cancer (mCRPC): Safety and baseline (BL) characteristics of U.S. patients (Pts) by prior/concomitant treatment (Tx)

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Background: Ra-223, a targeted alpha therapy, extended survival and had a favorable safety profile at 3 years’ follow up in pts with mCRPC in the pivotal phase 3 ALSYMPCA trial. The maturing global, prospective, single-arm, observational REASSURE study, designed to evaluate long-term safety at 7 years’ follow up, enrolled pts with mCRPC with bone metastases planned to receive Ra-223. Methods: We performed a descriptive analysis of safety and BL characteristics of US pts according to prior or concomitant abiraterone/enzalutamide (abi/enza) or prior docetaxel/cabazitaxel (chemo) using data from the first planned interim analysis (pts receiving ≥1 Ra-223 dose; median follow up 8 mo). Results: 244 US pts were included; 80% had no prior chemo. Prior abi/enza and/or chemo pts had higher median BL PSA and were less likely to complete 5-6 doses (Table). Subgroups had similar median ALP, LDH and Hb. Overall, drug-related tx-emergent AEs occurred in 71 pts (29%) and serious AEs in 9 (3.7%). Most common AEs were diarrhea, fatigue and anemia. AE incidence was numerically higher in pts who received prior chemo and/or abi/enza. Clinical trial information: NCT02141438. Conclusions: To date, REASSURE has not revealed any new safety findings and most pts complete 5-6 Ra-223 doses in routine US clinical practice. Pts with prior tx lines had lower Ra-223 tx completion and higher AE incidence, likely reflecting greater disease burden, as evidenced by higher median BL PSA.[Table: see text]

Cryoablation for locally advanced clinical stage T3 prostate cancer: a report from the Cryo-On-Line Database (COLD) Registry

OBJECTIVE

To assess the oncological and functional outcomes of primary prostate cryoablation for men with clinical stage T3 (cT3) prostate cancer, as although radical prostatectomy (RP) or external beam radiotherapy (EBRT) are the standard treatments for locally advanced cT3 prostate cancer some patients opt for nonextirpative prostate cryoablation instead.

PATIENTS AND METHODS

The Cryo-On-Line Database (COLD) Registry was queried to identify patients with cT3 prostate cancer treated with whole-gland cryoablation (366 patients). We assessed biochemical disease-free survival (bDFS) using the Phoenix definition and determined reported rates of urinary incontinence and retention, sexual activity, and rectourethral fistulisation after treatment. Patients were subsequently assessed according to whether they were administered neoadjuvant androgen-deprivation therapy or not (ADT; 115 patients, 31.4%).

RESULTS

For the entire cohort, the 36- and 60-month bDFS rates were 65.3% and 51.9%, respectively. Patients who received neoadjuvant ADT had statistically nonsignificantly higher 36- and 60-month bDFS rates (68.0% and 55.4%, respectively) than patients who did not receive neoadjuvant ADT (55.3% and 36.9%, respectively). The after treatment urinary incontinence rate was 2.6%; urinary retention rate, 6.0%; sexual activity rate, 30.4%; and rectourethral fistulisation rate, 1.1%.

CONCLUSIONS

Cryoablation for patients with cT3 prostate cancer leads to less favourable bDFS than that after RP or RT for the same group of men. The after treatment rectourethral fistulisation rates for patients with cT3 disease are higher than in those with organ-confined prostate cancer treated with cryoablation; however, urinary dysfunction and sexual activity rates are similar for men with cT3 to those reported from this same registry in men with cT2 disease. The addition of neoadjuvant ADT (though not studied prospectively here) should be strongly considered if a patient with cT3 prostate cancer is to be treated with cryoablation.

Serum IGF-1 levels in men with advanced prostate cancer treated with the ERα agonist, GTx-758

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Background: The insulin pathway and, in particular, insulin-like growth factor-1 (IGF-1), has been implicated in the development of prostate cancer, and serum IGF-1 levels have been associated with advanced disease. GTx-758, an ERα agonist that is being evaluated for the treatment of advanced prostate cancer, reduces serum total testosterone (T) and free T and increases SHBG. Herein, we compare the effects of GTx-758 and leuprolide on serum IGF-1 levels in men with advanced prostate cancer treated with ADT. Methods: In a Phase II study (G200705), men with advanced prostate cancer (n=159) received 1000 mg or 2000 mg of GTx-758 daily or leuprolide. Serum samples were collected from all of the men in the study and serum IGF-1 levels (ng/ml) were analyzed by a reference laboratory. All p values describe the comparison of GTx-758 treatment groups to the leuprolide treated men. Results: Through day 90, in men receiving the 1000 mg and 2000 mg doses of GTx-758 , serum IGF-1 levels were decreased by more than 70 ng/ml (greater than 50%), while levels stayed constant or increased slightly in men on leuprolide (p<0.001). As a result of an increased risk of venous thromboembolic events (VTEs) at these higher doses of GTx-758, the trial was stopped prior to its completion, and not all of the men in the study reached the 90 day treatment date (92 men reached that date). Conclusions: In men with advanced prostate cancer, the ERα agonist, GTx-758, can decrease the active form of testosterone, serum free T, to significantly lower levels than leuprolide. Patients receiving GTx-758 experienced a significant decrease in serum IGF-1. Since changes in insulin metabolism are involved in regulating prostate cancer as well as bone and systemic metabolism, the observed decreases in IGF-1 could be significant. A Phase II clinical trial utilizing lower doses of GTx-758 (G200712) is currently ongoing to determine if similar effects can be observed with a lower rate of VTEs. Clinical trial information: NCT01326312.

Effect of GTx-758, an ERα agonist, on serum-free testosterone and serum PSA in men with advanced prostate cancer

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Background: Androgen deprivation therapy (ADT) improves disease-free survival in men with advanced prostate cancer, but patients develop castrate resistant prostate cancer (CRPC); one of the causes of which is ineffective castration. Total serum testosterone (T) does not accurately predict prostatic levels of T. Further reduction of androgens in men with CRPC can result in improvement of survival. Herein we compare the effects GTx-758 an oral, selective estrogen receptor alpha (ERα) agonist versus leuprolide on total and free (unbound) serum T levels in men with advanced prostate cancer. Methods: In Phase II studies, men with advanced prostate cancer (n=164) received 1000 mg or 2000 mg GTx-758 daily or Lupron Depot (4 month), while men with CRPC (n=9) received 2000 mg GTx-758 daily. Serum concentrations of total T, free T, SHBG and PSA were determined at baseline and during treatment. Results: In ADT naïve advanced prostate cancer patients, 28 days of 1000 mg or 2000 mg daily GTx-758 or Lupron therapy castrated (T<50ng/dL) 50, 31 and 100% of patients, reducing mean serum total T in castrated patients to 23±14, 19±9 and 14±7 ng/dL, respectively. However, treatment with 1000 mg or 2000 mg GTx-758 daily reduced mean free T levels to a greater extent (0.9±0.7 and 0.7±0.7 pg/mL, respectively) than Lupron (1.7±1.1 pg/mL). Changes in PSA at 28 days were more closely associated with the observed changes in free T, with reductions of 74, 72 and 56% for 1000 mg, 2000 mg doses of GTx-758 and Lupron, respectively. In CRPC patients, 2000 mg GTx-758 daily did not further reduce serum total T levels, but did result in free T reductions and PSA decreases from baseline following 15 days of therapy in all of the men maintained on ADT with LHRH agonists alone. Conclusions: Although GTx-758 and LHRH based ADT both reduce total serum T and PSA levels in ADT naïve advanced prostate cancer patients, free T was rapidly reduced to a greater degree in the GTx-758 treated patients. In men with CRPC, GTx-758 therapy resulted in significant reductions in free T and resultant PSA declines. The ability of GTx-758 to reduce free T provides a unique mechanism to treat men with advanced prostate cancer and CRPC. Clinical trial information: NCT01326312.

Progastrin expression predisposes mice to colon carcinomas and adenomas in response to a chemical carcinogen

BACKGROUND & AIMS

Processing intermediates of preprogastrin (gly-gastrin and progastrin), termed nonamidated gastrins, are mitogenic for several cell types including colonic epithelial cells. However, presently it is not known if nonamidated gastrins play a role in colon carcinogenesis and if the effects are similar to those of amidated gastrins.

METHODS

Colon carcinogenesis in response to azoxymethane (AOM) was examined in transgenic mice overexpressing either progastrin (hGAS) or amidated gastrin (INS-GAS), compared with that in wild-type (WT) mice.

RESULTS

In AOM-treated groups, the total number of tumors per colon was significantly higher in hGAS (4.8+/-0.34) than INS-GAS (3.0+/-0.16) and WT (2.7+/-0.35) mice. Total numbers of adenocarcinomas and adenomas per animal colon were also significantly higher in hGAS than INS-GAS and WT mice. The size of the tumors was greater in hGAS mice, resulting in a significantly higher tumor burden per mouse in the hGAS mice than INS-GAS and WT mice. Although >90% of the tumors were located in the distal half of the colon in INS-GAS and WT mice, a significant number (42%) were present at the proximal end of the colon in hGAS mice.

CONCLUSIONS

The results suggest that the risk for developing colon carcinomas and adenomas in response to AOM is significantly increased in mice expressing high levels of progastrin, but not amidated gastrins.

Mice overexpressing progastrin are predisposed for developing aberrant colonic crypt foci in response to AOM

Recent studies show that nonamidated gastrins (Gly-gastrin and progastrin) stimulate colonic proliferation. However, the role of nonamidated vs. amidated gastrins in colon carcinogenesis has not been defined. We measured intermediate markers of carcinogenesis in transgenic mice overexpressing either progastrin (hGAS) or amidated gastrin (INS-GAS) in response to azoxymethane (AOM). The hGAS mice showed significantly higher numbers of aberrant crypt foci (140-200% increase) compared with that in wild-type (WT) and INS-GAS mice (P < 0.05) after AOM treatment. The bromodeoxyuridine-labeling index of colonic crypts also was significantly elevated in hGAS mice vs. that in WT and INS-GAS mice. The results therefore provide evidence for a mitogenic and cocarcinogenic role of nonamidated gastrins (progastrin), which is apparently not shared by the amidated gastrins. Although nonamidated gastrins are now believed to mediate mitogenic effects via novel receptors, amidated gastrins mediate biological effects via different receptor subtypes, which may explain the difference in the cocarcinogenic potential of nonamidated vs. amidated gastrins. In conclusion, our results provide strong support for a cocarcinogenic role for nonamidated gastrins in colon carcinogenesis.

Nitric oxide synthase distribution during implantation in the mouse

The peri-implantation period is a critical time during murine development. Although the importance of nitric oxide has been demonstrated during gestation, its role in implantation has not been fully defined. The aim of this study was to quantify (by Western blotting) two prominent nitric oxide synthase (NOS) isoforms, inducible (iNOS) and endothelial (eNOS) and localize all three forms [iNOS, eNOS, and neuronal (nNOS)] by immunohistochemistry in uterine tissue from days 4 through 8 of pregnancy. By day 6, iNOS values were significantly elevated in implantation sites compared with interimplantation regions and continued to rise through day 8. Analysis of eNOS was similar, but implantation site values peaked by days 6 and 7. Labelled iNOS cells were within the decidua, around myometrial vessels, and within the ectoplacental cone. At implantation, eNOS was conspicuous, displaying label adjacent to the embryo in vessels of the primary decidual zone. nNOS was localized mainly in the mesometrium and myometrium and did not appear to change throughout the peri-implantation period. The increased iNOS and eNOS values following implantation in the embryonic site may imply roles in tissue remodelling, immunosuppression and vasoregulation. Nitric oxide may play an important role in the mechanisms of implantation where these factors are keys to successful pregnancy.

Inducible nitric oxide synthase is present in the rat placenta at the fetal-maternal interface and decreases prior to labour

The aim of this study was to investigate the expression and distribution patterns of the inducible isoform of nitric oxide synthase (iNOS) in rat placenta during gestation and term labour. The expression of iNOS isoform was assessed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting with monoclonal antibodies. Two specific bands were detected corresponding to 135 and 124 kDa in all placenta samples. The upper band (135 kDa) was identified as iNOS due to its correspondence with the band obtained with mouse macrophages (positive control). Compared with its concentrations on day 16, iNOS decreased steadily toward the end of gestation to approximately 37% on day 20, 20% on day 22 before labour and 12% during labour (p < 0.01). The lower band (124 kDa) drastically increased (to almost double) from day 16 to day 18 but returned to initial values on day 22, during delivery. Immunohistochemical staining of placentae at day 16 and 22 using rabbit polyclonal anti-iNOS antibody revealed labelling specifically concentrated in the trophospongial cell layer, at the fetal-maternal interface. The most conspicuous iNOS staining was associated with islands of cells referred to as vacuolated 'glycogen cells'. Staining was greatly decreased during labour. The changes in placental iNOS expression suggest a 'paracrine' role for NO in regulating uterine contractility, blood flow and immunosuppression required for pregnancy maintenance. NO withdrawal at term may also be involved in the initiation of labour.

The effect of benzo[a]pyrene on sponges as model organisms in marine pollution

The majority of the investigations were performed with the marine sponge Tethya lyncurium at concentrations of 2 X 10(-8) to 1 X 10(-11) g/ml of benzo[a]pyrene (BaP). Sea-pollution was characterized as BaP equivalent activity in the Ames test. Increased activity of ornithine decarboxylase (ODC) was observed when sponges were artificially exposed at polluted marine areas for 3 weeks. In contrast to the situation in higher animals no ODC induction of the fast type was observed. Mixed function oxygenases (MFO) were not detected in sponges nor could they be induced as in vertebrates. BaP was absorbed by Tethya and concentrated 30--60-fold. In live, but not dead, artificially perfused sponges [3H]- and [14C]BaP-radiolabeled became firmly associated with DNA, RNA and protein of the sponges. The association persisted in isolated fractions, in nucleotides, in nucleosides and in protein hydrolysates. The BaP binding ratio to DNA was found to be strongly correlated to the concentration of BaP. Light modifies BaP and thus enables binding. In the dark only very low association, if any, is observed. The possible consequences of these findings are discussed.

Assessing consequences of marine pollution by hydrocarbons using sponges as model organisms

Pollution has been assessed as a mutagenic activity determined by the Ames test, using radiolabelled benzo[a]pyrene (BaP) as a model pollutant. Experimental animals were sponges, mainly Tethya lyncurium from the Northern Adriatic and from the Pacific near Catalina Island, California, U.S.A. Changes in ornithine decarboxylase (ODC) activity (ODC; EC 4.1.1.17) and polyamine concentrations with and without pollution were observed. There is a slow rise in ODC activity during the course of three-weeks exposure and a fast increase of polyamine levels during the course of one day. Mixed function oxygenase (MFO; EC 1.14) activity could not be detected in sponges. There was a significant concentration dependent coupling of radioactive BaP derivatives (BaPD) to the macromolecular fractions; the highest in protein, X 1000 greater than DNA and X 500 greater than RNA. Coupling is light-mediated and drops to zero in the dark. However when activated microsomal fractions from fish, that had been exposed to high level polycyclic aromatic hydrocarbon (PAH) pollution are added, dark incorporation rises to significant levels which can be decreased by the MFO inhibitor 7,8-benzoflavone (BP). The question of possible absence of DNA repair in the sponges and some implications are discussed.