Triptorelin in the management of prostate cancer

Molecular mechanisms underlying cyclophosphamide-induced cognitive impairment and strategies for neuroprotection in preclinical models

Cyclophosphamide has drastically enhanced the expectancy and quality of life of cancer patients. However, it is accompanied by diverse neurological complications which are considered a dose-limiting adverse effect. Neurotoxicity caused by cyclophosphamide can manifest in numerous manners including anxiety, depression, motor dysfunction and cognitive deficits. This review article offers an overview on cyclophosphamide-induced neurotoxicity, providing a unified point of view on the possible underlying molecular mechanisms including oxidative brain damage, neuroinflammation, apoptotic neuronal cell death as well as disruption of the balance of brain neurotransmitters and neurotrophic factors. Besides, this review sheds light on the promising protective agents that have been investigated using preclinical animal models as well as their biological targets and protection mechanisms. Despite promising results in experimental models, none of these agents has been studied in clinical trials. Thus, there is lack of evidence to advocate the use of any neuroprotective agent in the clinical setting. Furthermore, none of the protective agents has been evaluated for its effect on the anticancer activity of cyclophosphamide in tumor-bearing animals. Therefore, there is a great necessity for adequate well-designed clinical studies for evaluation of the therapeutic values of these candidates. Conclusively, this review summarizes the molecular mechanisms accounting for cyclophosphamide-induced neurotoxicity together with the potential protective strategies seeking for downgrading this neurological complication, thus enhancing the quality of life and well-being of cancer patients treated with cyclophosphamide.

Quantitative analysis of therapeutic peptides by CZE using multiple sample injection in hydrodynamically closed separation system

Therapeutic peptides have emerged as an innovative and promising class of therapeutic compounds in modern medicine. Synthetic peptide analogs triptorelin and lanreotide are known for their pronounced clinical versatility and potency. In this study, we present the development and validation of novel methods based on capillary zone electrophoresis performed in hydrodynamically closed system (HCS) and paired with ultraviolet detection and repeated injection sample introduction. To the best of our knowledge, we developed the first capillary electrophoresis-based method for the determination of lanreotide, and concurrently, the first HCS method for the determination of triptorelin. Maximal separation efficiency and signal intensity were achieved using background electrolytes composed of 50 mM formic acid with the addition of 0.05% (v/v) methyl-hydroxyethyl cellulose. The proposed methods exhibit favorable performance characteristics, namely, calibration curve (r2 exceeding 0.99), low limits of detection (0.25 µg/mL in a water matrix and 0.5 µg/mL in synthetic urine), acceptable precision (relative standard deviation ranging from 2.2% to 9.6% for intraday repeatability and between 5.2% and 14.9% for interday reproducibility), and accuracy (relative errors falling within the 91.1%-107.8% range). The method for triptorelin determination was then used for its quantification in a commercially available drug dosage form (powder for injection) and in spiked synthetic urine samples. The developed methods were also evaluated according to the novel blue applicability grade index, revealing their superior applicability. The results collectively point out the potential of the proposed methods for both quality control and clinical investigations.

Survival, treatment duration and costs of patients with prostate cancer treated with triptorelin in Italy: a study of administrative databases

Background

Several data support the efficacy/effectiveness, safety and favorable impact on quality of life of triptorelin treatment in patients with prostate cancer. However, little evidence is available concerning triptorelin use in the long term.

Methods

We analyzed data on triptorelin treatment in patients with prostate cancer in an integrated Italian administrative database, covering around 6 million health-assisted subjects throughout the country. Patients with at least one prescription for triptorelin in the period 2010-2020 and with no evidence of metastasis were included and followed up until 2021. Overall survival (OS) and duration of treatment were analyzed using Kaplan-Meier curves, starting from the date of first prescription.

Results

The cohort included a total of 3,411 patients (mean age: 76.8 ± 8.7 years), of whom 1,326 (38.9%) were treated with triptorelin only and 2,085 (61.1%) with triptorelin combined with an anti-androgen. Overall, 847 (24.8%) patients with prostate cancer died and 1,037 (30.4%) had a treatment switch during the follow-up period, and both the median OS and median duration of treatment were not reached in both groups. The mean annual total cost per patient was estimated as 5,574 €, with almost half of the costs related to medication expenses (2,737 €).

Conclusions

We found a long survival and duration of triptorelin treatment in this population of Italian patients with prostate cancer. This study with a long follow-up period further highlights the usefulness of healthcare utilization databases to integrate results obtained from clinical studies with those from everyday clinical practice.

Current research status of anti-cancer peptides: Mechanism of action, production, and clinical applications

The escalating rate of cancer cases, together with treatment deficiencies and long-term side effects of currently used cancer drugs, has made this disease a global burden of the 21st century. The number of breast and lung cancer patients has sharply increased worldwide in the last few years. Presently, surgical treatment, radiotherapy, chemotherapy, and immunotherapy strategies are used to cure cancer, which cause severe side effects, toxicities, and drug resistance. In recent years, anti-cancer peptides have become an eminent therapeutic strategy for cancer treatment due to their high specificity and fewer side effects and toxicity. This review presents an updated overview of different anti-cancer peptides, their mechanisms of action and current production strategies employed for their manufacture. In addition, approved and under clinical trials anti-cancer peptides and their applications have been discussed. This review provides updated information on therapeutic anti-cancer peptides that hold great promise for cancer treatment in the near future.

Naturally occurring, natural product inspired and synthetic heterocyclic anti-cancer drugs

This chapter describes the importance and activity of a huge number of commercially available naturally occurring, natural product derived or synthetic heterocyclic anti-cancer drugs.

Using porphyrins as albumin-binding molecules to enhance antitumor efficacies and reduce systemic toxicities of antimicrobial peptides

Antimicrobial peptides (AMPs) are originally developed for anti-infective treatments. Because of their membrane-lytic property, AMPs have been considered as candidates of antitumor agents for a long time. However, their antitumor applications are mainly hampered by fast renal clearance and high systemic toxicities. This study proposes a strategy aiming at addressing these two issues by conjugating AMPs with porphyrins, which bind to albumin increasing AMPs' resistance against renal clearance and thus enhancing their antitumor efficacies. Porphyrins' photodynamic properties can further augment AMPs' antitumor effects. In addition, circulating with albumin ameliorates AMPs' systemic toxicities, i.e. hemolysis and organ dysfunctions. As an example, we conjugated an AMP, K6L9, with pyropheophorbide-a (PPA) leading to a conjugate of PPA-K6L9. PPA-K6L9 bound to albumin with a K_D value at the sub-micromolar range. Combining computational and experimental approaches, we characterized the molecular interaction of PPA-K6L9 with albumin. Furthermore, PPA-conjugation promoted K6L9' antitumor effects by prolonging its in vivo retention time, and reduced the hemolysis and hepatic injuries, which confirmed our design strategy.

Silica-Based Nanoparticles as Drug Delivery Vehicles for Prostate Cancer Treatment

Prostate cancer (PCa) is one of the most commonly diagnosed cancers and is the fifth common cause of cancer-related mortality in men. Current methods for PCa treatment are insufficient owing to the challenges related to the non-specificity, instability and side effects caused by the drugs and therapy agents. These drawbacks can be mitigated by the design of a suitable drug delivery system that can ensure targeted delivery and minimise side effects. Silica based nanoparticles (SBNPs) have emerged as one of the most versatile materials for drug delivery due to their tunable porosities, high surface area and tremendous capacity to load various sizes and chemistry of drugs. This review gives a brief overview of the diagnosis and current treatment strategies for PCa outlining their existing challenges. It critically analyzes the design, development and application of pure, modified and hybrid SBNPs based drug delivery systems in the treatment of PCa, their advantages and limitations.

Therapies Targeted to Androgen Receptor Signaling Axis in Prostate Cancer: Progress, Challenges, and Hope

Prostate cancer is the mostly commonly diagnosed non-cutaneous malignancy and the second leading cause of cancer-related death affecting men in the United States. Moreover, it disproportionately affects the men of African origin, who exhibit significantly greater incidence and mortality as compared to the men of European origin. Since androgens play an important role in the growth of normal prostate and prostate tumors, targeting of androgen signaling has remained a mainstay for the treatment of aggressive prostate cancer. Over the years, multiple approaches have been evaluated to effectively target the androgen signaling pathway that include direct targeting of the androgens, androgen receptor (AR), AR co-regulators or other alternate mechanisms that impact the outcome of androgen signaling. Several of these approaches are currently in clinical practice, while some are still pending further development and clinical evaluation. This remarkable progress has resulted from extensive laboratory, pre-clinical and clinical efforts, and mechanistic learnings from the therapeutic success and failures. In this review, we describe the importance of androgen signaling in prostate cancer biology and advances made over the years to effectively target this signaling pathway. We also discuss emerging data on the resistance pathways associated with the failure of various androgen signaling- targeted therapies and potential of this knowledge for translation into future therapies for prostate cancer.

[Study of the beneficial effects of triptorelin on lower urinary tract symptoms in Algeria in patients with non-localized prostate cancer]

INTRODUCTION

This study aims to assess the effectiveness of triptorelin on lower urinary tract symptoms (LUTS) in Algerian patients with non-localized prostate cancer in routine practice.

MATERIALS

This prospective, observational, non-interventional, multicentre study was conducted in Algeria. Included patients who had locally advanced or metastatic prostate cancer and were treated with triptorelin 11.25mg given every 12 weeks. LUTS were evaluated with the International Prostate Symptom Score (IPSS) until week 48 after treatment initiation. An IPSS>7 indicated moderate to severe LUTS. The primary objective of the study was to determine the distribution of IPSS at week 48.

RESULTS

This study enrolled 193 patients at 21 centres. A total of 144 participants had IPSS available at baseline and after baseline (136 patients had moderate to severe LUTS and eight had mild LUTS at baseline). At week 48, amongst the 116 patients with IPSS available and moderate to severe LUTS at baseline, 94 (81.0%) had moderate to severe LUTS and 22 (19.0%) had mild LUTS. At week 48, the eight patients with mild symptoms at baseline remained in this category. The proportion of patient with severe LUTS decreased from 53.7% at baseline to 12.1% at week 48. Adverse events were reported in 22.9% of participants.

CONCLUSION

A reduction of LUTS is observed in patients with locally advanced or metastatic prostate cancer treated with triptorelin in routine practice. This is in agreement with similar observational studies of triptorelin conducted in other countries.

LEVEL OF PROOF

4.

Are all gonadotrophin-releasing hormone agonists equivalent for the treatment of prostate cancer? A systematic review

To review direct comparative studies of the gonadotrophin-releasing hormone (GnRH) agonists goserelin, triptorelin, and leuprorelin for the treatment of prostate cancer, and identify whether there are meaningful clinical differences between these agents. In June 2017, the following searches were performed independently by two reviewers in PubMed: (i) 'prostate cancer' and 'triptorelin' and 'leuprorelin', (ii) 'prostate cancer' and 'triptorelin' and 'goserelin', and (iii) 'prostate cancer' and 'goserelin' and 'leuprorelin', without time restriction. Duplicates were deleted. Relevant conference abstracts were also screened. A total of 16 direct comparative trials were identified: 12 reported on efficacy outcomes, four on safety/tolerability, and five on the convenience of administration/user perceptions. These studies are restricted in terms of patient numbers, formulations assessed, and endpoints measured; none were adequately powered for survival outcome measures. Studies reporting on efficacy endpoints did not show major differences in the ability of these GnRH agonists to reduce levels of testosterone or prostate-specific antigen. Some studies suggest differences in short- or long-term testosterone control, the rate of injection site adverse events, and patient/healthcare professional perceptions, but definitive conclusions cannot be drawn from the existing evidence. Few direct comparative trials of GnRH agonists have been conducted. Whilst GnRH agonists provide a similar castration effect, there is not enough evidence to show that GnRH agonists are equivalent.

Triptorelin for the relief of lower urinary tract symptoms in men with advanced prostate cancer: results of a prospective, observational, grouped-analysis study

BACKGROUND

Lower urinary tract symptoms (LUTSs) may develop in men with prostate cancer (PCa) and can impact quality of life (QoL). Gonadotropin-releasing hormone (GnRH) agonists as androgen deprivation therapy are standard treatment for PCa, however, data are limited on their effects on LUTSs. A grouped analysis of national observational, non-interventional studies initiated in clinical practice was performed to assess the effectiveness of triptorelin in reducing moderate or severe LUTSs, measured using the International Prostate Symptom Score (IPSS) in men with advanced or metastatic PCa.

METHODS

Men with PCa and LUTSs scheduled to receive triptorelin (3-month or 1-month extended release formulation) were recruited into prospective, non-interventional studies at centres in Algeria, Australia, Belgium, China, Hungary, Romania and South Korea. The primary effectiveness endpoint was the proportion of patients with moderate or severe LUTSs, assessed by IPSS, after 48 weeks. Secondary endpoints included: total IPSS, QoL due to urinary symptoms (IPSS Question 8) and prostate-specific antigen (PSA) levels at 24 and 48 weeks.

RESULTS

A total of 2701 patients were recruited; 1851 patients with moderate or severe LUTSs at baseline (IPSS > 7), received triptorelin and had follow-up IPSS (efficacy population). The proportion of patients with moderate or severe LUTSs was reduced to 67.2% from baseline at week 48, following a reduction to 75.9% at week 24: the overall time effect was significant (p < 0.001). QoL due to urinary symptoms significantly improved from a mean score of 3.7 at baseline, to adjusted means of 2.5 and 2.1, at weeks 24 and 48, respectively (p < 0.001 versus baseline). Mean PSA levels were reduced from 158.8 ng/ml at baseline to 11.5 and 16.0 ng/ml at weeks 24 and 48, respectively.

CONCLUSIONS

Within the limitations of these observational studies, improvements in LUTSs and QoL observed after 24 weeks and maintained at 48 weeks indicate that triptorelin-induced effects improve LUTSs in patients with advanced PCa.

Pharmacotherapeutic Targeting of G Protein-Coupled Receptors in Oncology: Examples of Approved Therapies and Emerging Concepts

G protein-coupled receptors (GPCRs) are involved in numerous physio-pathological processes, including the stimulation of cancer progression. In this regard, it should be mentioned that although GPCRs may represent major pharmaceutical targets, only a few drugs acting as GPCR inhibitors are currently used in anti-tumor therapies. For instance, certain pro-malignancy effects mediated by GPCRs are actually counteracted by the use of small molecules and peptides that function as receptor antagonists or inverse agonists. Recently, humanized monoclonal antibodies targeting GPCRs have also been developed. Here, we review the current GPCR-targeted therapies for cancer treatment, summarizing the clinical studies that led to their official approval. We provide a broad overview of the mechanisms of action of the available anti-cancer drugs targeting gonadotropin-releasing hormone, somatostatin, chemokine, and Smoothened receptors. In addition, we discuss the anti-tumor potential of novel non-approved molecules and antibodies able to target some of the aforementioned GPCRs in different experimental models and clinical trials. Likewise, we focus on the repurposing in cancer patients of non-oncological GPCR-based drugs, elucidating the rationale behind this approach and providing clinical evidence on their safety and efficacy.

Effect of triptorelin on lower urinary tract symptoms in Australian prostate cancer patients

Purpose

Prostate cancer is often comorbidly associated with lower urinary tract symptoms (LUTS), but few studies have assessed the effects of androgen deprivation therapy on LUTS in this patient group.

Patients and methods

We conducted a prospective, noninterventional, multicenter, observational study to assess the effectiveness of triptorelin (11.25 mg every 12 weeks) over 48 weeks in men presenting with local stage T3/4 prostate cancer and moderate to severe LUTS (International Prostate Symptom Score [IPSS] >7) in a routine practice setting in Australia.

Results

Of the 44 men who enrolled, effectiveness data were available for 39 men. By the end of the study, 30% of men no longer met the IPSS criteria for moderate to severe LUTS. The proportion of patients with moderate to severe LUTS was 69.6% (16/23) at week 48 and 76.9% (30/39) at the last available visit (coprimary outcomes). An IPSS reduction of ≥3 from week 0 was observed in 47% of men at week 4, 56% at week 24, 61% (14/23) at week 48, and 61.5% (24/39) at the last available visit. Quality of life was rated as mostly satisfied-to-delighted by 39.5% of patients at week 0, 53.9% at week 24, and 77.3% at week 48. Triptorelin was well tolerated with 8 treatment-related adverse events reported, half of which were hot flushes; 5 patients discontinued due to the reported treatment-related adverse events.

Conclusion

This observational study suggests that triptorelin improves moderate to severe LUTS in prostate cancer patients in a routine clinical practice setting.

Mechanistic Study on Triptorelin Action in Protecting From 5-FU-Induced Ovarian Damage in Rats

Triptorelin, a kind of GnRH agonist, is widely used in the treatment of hormone-responsive cancers in the clinic. This study aimed to discover the underlying mechanism of triptorelin in protection from 5-fluorouracil (5-FU)-induced ovarian damage in Sprague–Dawley rats. In the present study, after using 5-FU to induce ovarian damage in rats, body weight and wet ovaries were weighed, the levels of estradiol (E2), follicle-stimulating hormone (FSH), and anti-Müllerian hormone (AMH) in blood were detected, and the expression of Bcl-2, Bax, and NF-κB was determined. It suggested that, compared to the control, body weight gain, the ratio of ovarian wet weight to body weight, primary follicle numbers, and the levels of AMH were significantly decreased, while the concentration of E2 and FSH was heavily increased following 5-FU administration. In contrast, after coadministration of triptorelin with 5-FU, the ratio of ovarian wet weight to body weight and the levels of AMH were significantly increased, whereas the level of E2 and FSH was decreased significantly when compared with the 5-FU group. Furthermore, at indicated times, 5-FU led to the reduced Bcl-2 and NF-κB expression and increased Bax expression while triptorelin plus 5-FU increased Bcl-2 and NF-κB expression and decreased Bax expression. It was indicated that triptorelin could protect rats from 5-FU-induced ovarian damage by modulation of hormones, Bcl-2, Bax, and NF-κB. These results might highlight the mechanism of triptorelin as a protective agent in clinical chemotherapy for ovarian damage.

An Update on Triptorelin: Current Thinking on Androgen Deprivation Therapy for Prostate Cancer

Androgen deprivation therapy (ADT) is the mainstay palliative treatment for men with locally advanced and metastatic prostate cancer, and aims to reduce testosterone to levels obtained by surgical castration. Use of gonadotropin-releasing hormone (GnRH) agonists predominates among the ADT options. The GnRH agonist, triptorelin is a first-line hormonal therapy that has demonstrated efficacy and safety in clinical trials of patients with locally advanced non-metastatic or metastatic disease. Sustained-release 1-, 3- and 6-month formulations of triptorelin, administered intramuscularly or subcutaneously, have been developed to provide improved flexibility and convenience for the patient. Head-to-head studies of GnRH agonists are lacking in the field of prostate cancer. Despite the inevitable progression to castration-resistant prostate cancer (CRPC) in most patients receiving ADT, monitoring of testosterone levels needs to improve in routine practice and physicians should not overlook the benefits of continued ADT in their patients when introducing one of the various new treatment options for CRPC. For improved survival outcomes, there remains a need to tailor ADT treatment regimens, novel hormonal agents and chemotherapy according to the individual patient with advanced prostate cancer.

Therapeutic Rationales, Progresses, Failures, and Future Directions for Advanced Prostate Cancer

Patients with localized prostate cancer (PCa) have several therapeutic options with good prognosis. However, survival of patients with high-risk, advanced PCa is significantly less than patients with early-stage, organ-confined disease. Testosterone and other androgens have been directly linked to PCa progression since 1941. In this review, we chronicle the discoveries that led to modern therapeutic strategies for PCa. Specifically highlighted is the biology of androgen receptor (AR), the nuclear receptor transcription factor largely responsible for androgen-stimulated and castrate-recurrent (CR) PCa. Current PCa treatment paradigms can be classified into three distinct but interrelated categories: targeting AR at pre-receptor, receptor, or post-receptor signaling. The continuing challenge of disease relapse as CR and/or metastatic tumors, destined to occur within three years of the initial treatment, is also discussed. We conclude that the success of PCa therapies in the future depends on targeting molecular mechanisms underlying tumor recurrence that still may affect AR at pre-receptor, receptor, and post-receptor levels.

Comparison of the Efficacy of Two Brands of Triptorelin (Microrelin and Diphereline) in Reducing Prostate-Specific Antigen and Serum Testosterone in Prostate Cancer: A Double-Blinded Randomized Clinical Trial

BACKGROUND

Gonadotropin-releasing hormone (GnRH) agonists initiate androgen deprivation in treating prostate cancer (PC). Triptorelin is a synthetic GnRH and many of its market brands such as Diphereline have been introduced so far.

OBJECTIVES

We compared the efficacy of a sustained-release formulation of Triptorelin (Microrelin), domestically produced in Iran, and compared it with Diphereline in a double-blinded randomized clinical trial.

PATIENTS AND METHODS

Patients were randomly assigned to Group A (Microrelin S.R. 3.75 mg, Pooyesh Darou, Iran) and Group B (Diphereline S.R. 3.75 mg, IPSEN, France). Each patient received monthly intramuscular injections. Prostate-specific antigen (PSA) and circulatory testosterone were measured at baseline and after one, 3, and 6 months.

RESULTS

Each group contained 40 patients. In Group A, PSA was reduced from 75.78 ± 72.43 ng/mL to 1.93 ± 1.40 ng/mL after 6 months and testosterone was reduced from 3.50 ± 1.12 nmol/L to 0.81 ± 0.05 nmol/L. There was no significant difference between the efficacy of Microrelin and Diphereline. Two patients in the Microrelin Group and one patient in the Diphereline Group failed to reach medical castration (testosterone < 1.7 nmol/L), which illustrates that the power of Microrelin and Dipherelin in initiating medical castration is about 95% and 97.5%, respectively.

CONCLUSIONS

Our study showed that Microrelin is as effective as Diphereline in reducing PSA and testosterone and can be recommended to initiate medical castration in patients with PC.

A prospective, observational grouped analysis to evaluate the effect of triptorelin on lower urinary tract symptoms in patients with advanced prostate cancer

OBJECTIVES

Few studies have assessed the effect of gonadotropin-releasing hormone (GnRH) agonists, such as triptorelin, on lower urinary tract symptoms (LUTS) in patients with advanced prostate cancer. Therefore, multiple, national observational, noninterventional studies were initiated to assess the effectiveness of triptorelin in reducing moderate or severe LUTS [International Prostate Symptom Score (IPSS) >7] in men with prostate cancer starting triptorelin therapy in clinical practice.

METHODS

Prospective, noninterventional, multicentre studies of LUTS located in Algeria, Belgium, China, Hungary, Romania and South Korea, in patients who were scheduled to receive triptorelin (3-month extended release or 1-month formulation) in clinical practice. The primary effectiveness endpoint was the proportion of patients with moderate or severe LUTS after 48 weeks as assessed by IPSS. Secondary endpoints included the distribution of IPSS categories, total IPSS and prostate-specific antigen (PSA) levels at baseline, 24 and 48 weeks.

RESULTS

In total, 2461 patients were recruited in the studies; 1282 patients had moderate or severe LUTS at baseline (IPSS > 7), received triptorelin and had follow-up IPSS. Mean total IPSS was reduced from 18.2 [95% confidence interval (CI) 17.8-18.5] at baseline to 11.9 (95% CI 11.5-12.3; p < 0.001) and 10.6 (95% CI 10.2-11.0; p < 0.001) at weeks 24 and 48, respectively. Mean PSA levels were reduced from 117.9 ng/ml (95% CI 93.8-141.9) at baseline to 8.5 ng/ml (95% CI 5.2-11.7) and 16.6 ng/ml (95% CI 7.4-25.8) at weeks 24 and 48, respectively. There was a significant correlation between total IPSS change from baseline and PSA change from baseline at weeks 24 and 48 (ρ = 0.3 and 0.2, p < 0.001).

CONCLUSIONS

The improvement in LUTS in men with locally advanced or metastatic prostate cancer after 24-48 weeks suggests that triptorelin is effective in improving LUTS in this subgroup of patients.

Efficacy of triptorelin pamoate 11.25 mg administered subcutaneously for achieving medical castration levels of testosterone in patients with locally advanced or metastatic prostate cancer

OBJECTIVES

Gonadotropin-releasing hormone agonists are widely used as androgen deprivation therapy in many men with locally advanced or metastatic prostate cancer. Gonadotropin-releasing hormone agonists are delivered by intramuscular injection every 1, 3 or 6 months, but in some patients subcutaneous injection may be more appropriate. This study assessed the efficacy and safety profile of the gonadotropin-releasing hormone agonist, triptorelin pamoate, when administered by the subcutaneous route.

METHODS

In this multicentre, open-label, single-arm study, androgen deprivation therapy-naïve men with locally advanced or metastatic prostate cancer received the gonadotropin-releasing hormone agonist triptorelin pamoate 11.25 mg (3-month formulation) by the subcutaneous route twice (at baseline and 13 weeks later). The co-primary efficacy endpoints were the proportion of patients with a castration level of serum testosterone (<50 ng/dl) after 4 weeks, and of these, those still castrated after 26 weeks.

RESULTS

Of the 126 treated patients, 123 [97.6%; 95% confidence interval (CI): 93.2-99.5)] were castrated 4 weeks after the first subcutaneous injection, and 115/119 patients (96.6%; 95% CI: 91.6-99.1) castrated at 4 weeks maintained castration at 26 weeks. Median prostate-specific antigen levels were reduced by 64.2 and 96.0% at 4 and 26 weeks, respectively. The probability of maintaining a testosterone level <20 ng/dl up to 26 weeks was 90.0% (95% CI: 85.0-95.0). The most frequently occurring treatment-related adverse events were typical of gonadotropin-releasing hormone agonist treatment (hot flushes, increased weight, erectile dysfunction and hyperhidrosis).

CONCLUSIONS

This study demonstrates that triptorelin pamoate 11.25 mg administered by the subcutaneous route every 3 months is as efficacious and well tolerated as administration via the intramuscular route in men with locally advanced or metastatic prostate cancer.

Enhanced Degradation of Lactide-co-Glycolide Polymer with Basic Nucleophilic Drugs

The purpose of this study was to examine the degradative effect of weakly basic nucleophilic drugs on a lactide-co-glycolide (PLGA) polymer in a microsphere formulation. Biodegradable PLGA microspheres of two second-generation atypical antipsychotics, Risperidone and Olanzapine, were manufactured using a solvent extraction/evaporation technique. The effect of drug content, buffer pH and temperature on polymer molecular weight and degradation, were examined via a series of experiments and compared against a control (Placebo PLGA microspheres). In comparison to Placebo microspheres, significant polymer molecular weight reduction was observed upon encapsulation of varying levels of either Risperidone or Olanzapine. There was excellent correlation between the extent of molecular weight reduction during manufacture and the amount of encapsulated drug in the microspheres. Subsequent studies on polymer degradation showed: the following (a) the Placebo and Olanzapine microspheres followed pseudo first order kinetics, (b) Risperidone microspheres exhibited biphasic degradation profiles, and (c) polymer degradation was dependent on temperature, not pH. The findings of these studies show that encapsulation of weakly basic nucleophile type drugs into PLGA can accelerate the biodegradation of the PLGA and have major implications on the design of polymeric microsphere drug delivery systems.