Effects of carboplatin on the testis. A histological study

Alkylating agents-induced gonadotoxicity in prepubertal males: Insights on the clinical and preclinical front

Rising cure rates in pediatric cancer patients warrants an increased attention toward the long-term consequences of the diagnosis and treatment in survivors. Chemotherapeutic agents can be gonadotoxic, rendering them at risk for infertility post-survival. While semen cryopreservation is an option that can be provided for most (post)pubertal boys before treatment, this is unfortunately not an option prepubertal in age, simply due to the lack of spermatogenesis. Over the last couple of years, studies have thus focused on better understanding the testis niche in response to various chemotherapeutic agents that are commonly administered and their direct and indirect impact on the germ cell populations. These are generally compounds that have a high risk of infertility and have been classified into risk categories in curated fertility guidelines. However, with it comes the lack of evidence and the challenge of using informative models and conditions most reflective of the physiological scenario, in short, the appropriate study designs for clinically relevant outcomes. Besides, the exact mechanism(s) of action for many of these "risk" compounds as well as other agents is unclear. Understanding their behavior and effect on the testis niche will pave the way for incorporating new strategies to ultimately combat infertility. Of the various drug classes, alkylating agents pose the highest risk of gonadotoxicity as per previously established studies as well as risk stratification guidelines. Therefore, this review will summarize the findings in the field of male fertility concerning gonadotoxicity of akylating agents as a result of chemotherapy exposure.

Ivermectin prevents stress-induced testicular damage in juvenile rats

Ivermectin is a popular antiparasitic drug used in veterinary and human medicine. Studies by our group have shown that therapeutic doses of ivermectin induce some brain and behavioral impairments, especially in the reproductive sphere. So far, the studies were focused in adulthood. Considering that juveniles are more susceptible to drugs during developmental stages and both farm/domestic animals and humans have been medicated with ivermectin in youth, it is necessary to evaluate the possible harm effects in youth. The stress variable is also important, as it potentially influences the effects produced by ivermectin. Therefore, the objective of this study was to evaluate morphofunctional and hormonal reproductive aspects of juvenile rats exposed to ivermectin and/or stressed. Prepubertal male rats were treated with 0.2 or 1.0 mg/kg of ivermectin (a therapeutic dose and a higher dose, respectively). Rats were also submitted to a restraint stress session. The testis morphology and histology were analyzed and plasma testosterone levels were measured. The two doses of ivermectin did not induce a biologically relevant effect on testis and testosterone levels of rats. However, restraint stress impaired macroscopic and microscopic morphometric and stereological parameters, as well as the histology of the testis: it increased the relative testis weight, the tubular diameter, the tubular luminal diameter, and the tubular cellular index, and injured the interstitial area. Previous treatment of juvenile rats with ivermectin prevented most of the stress-induced testes injuries. In conclusion, in addition to be a remarkable antiparasitic agent, ivermectin prevented stress-induced testes injuries in juvenile rats.

Comparative gonadotoxicity of the chemotherapy drugs cisplatin and carboplatin on prepubertal mouse gonads

The treatment of childhood cancer with chemotherapy drugs can result in infertility in adulthood. Newer generations of drugs are developed to replace parent drugs, with the potential benefits of less toxic side effects. For platinum alkylating-like drugs, in contrast to the parent compound cisplatin, the newer-generation drug carboplatin is reported to have reduced toxicity in some respects, despite being administered at 5-15 times higher than the cisplatin dose. Whether carboplatin is also less toxic than cisplatin to the reproductive system is unknown. Here we compare the gonadotoxic impact of cisplatin and carboplatin on female and male mouse prepubertal gonads. In vitro cultured CD1 mouse ovaries or testis fragments were exposed to either cisplatin or carboplatin for 24 h on Day 2 of culture and analysed by Day 6. A dose response for each drug was determined for the ovary (0.5, 1 & 5 μg/ml cisplatin and 1, 5 & 10 μg/ml carboplatin) and the testis (0.01, 0.05 & 0.1 μg/ml cisplatin and 0.1, 0.5 & 1 μg/ml carboplatin). For the ovary, unhealthy follicles were evident from 1 μg/ml cisplatin (73% unhealthy, P = 0.001) and 5 μg/ml carboplatin (84% unhealthy, P = 0.001), with a concomitant reduction in follicle number (P = 0.001). For the testis, the proliferating germ cell population was significantly reduced from 0.05 μg/ml cisplatin (73% reduction, P = 0.001) and 0.5 μg/ml carboplatin (75% reduction, P = 0.001), with no significant impact on the Sertoli cell population. Overall, results from this in vitro animal model study indicate that, at patient equivalent concentrations, carboplatin is no less gonadotoxic than cisplatin.

Mice with a Sertoli cell-specific knockout of the Ctr1 gene exhibit a reduced sensitivity to cisplatin-induced testicular germ cell apoptosis

Exposure to the chemotherapeutic agent cis-diamminedichloroplatinum(ii) (cDDP) is well known to instigate acute and prolonged testicular injury in male patients.

Exposure to the chemotherapeutic agent cis-diamminedichloroplatinum(ii) (cDDP) is well known to instigate acute and prolonged testicular injury in male patients. Many investigators have hypothesized that cDDP-induced dysfunction of Sertoli cells (SCs) may, in part, account for the cDDP-induced lasting testicular injury. Nevertheless, the relative contribution of cDDP-induced SC injury versus direct effects on germ cells (GCs) to the pathogenesis of GC loss remains to be elucidated. The expression of the copper transporter 1 (CTR1) protein in cells directly corresponds with cDDP uptake and its cellular toxicity. Therefore, to discern the role of SCs in the pathogenic mechanism, mice were developed with a SC-specific disruption of the Ctr1 gene (SC^ΔCtr1) as a strategy to prevent their exposure to cDDP. Adult mice at postnatal day (PND) 60 were treated with 5 mg kg^–1 cDDP and then testis collected at 48 hours. A two-fold increase in GC-apoptosis occurred in the testis of cDDP-treated wildtype (WT) mice as compared to saline-treated WT mice. In contrast, cDDP-treated SC^ΔCtr1 mice exhibited only a half-fold increase in GC-apoptosis as compared to the saline-treated SC^ΔCtr1 mice. This reduced incidence of GC apoptosis in the SC^ΔCtr1 mice corresponded to a significantly lower level of platinum within the testis. Taken together, these findings reveal that the uptake of cDDP by CTR1 in SCs accounts for the accumulation of cDDP in the testis and plays a pivotal role in the pathogenic sequence of events leading to the loss of germ cells via apoptosis.

High Serum Estradiol and Heavy Metals Responsible for Human Spermiation Defect-A Pilot Study

INTRODUCTION

Spermiation is a process of releasing sperm into the lumen of seminiferous tubules. Failure in releasing sperm into the lumen is designated as spermiation defect. Spermiation defect cases present as oligo-azoospermia or azoospermia despite normal gonadotropins and testicular histology/cytology. Human spermiation defect never got attention to investigate infertility practice. Most of the information on spermiation defect, so far is from animal experiments. We assume some cases of non-obstructive azoospermia with normal gonadotropins and testicular histology/cytology could be due to spermiation defect.

AIM

The aim of the study was to find out the underlying aetiology in cases of human spermiation defect.

MATERIALS AND METHODS

A total of 13 cases of spermiation defect and 20 fertile men as control constituted study material. Cases were studied for chromosomal abnormalities by conventional karyotyping, sex chromosome mosaicism by interphase XY FISH, Yq microdeletion by STS PCR, sertoli cell quality (function) and quantity (numbers) by serum Anti-Mullerian Hormone (AMH) and inhibin B besides other hormones like Follicular Stimulating Hormone (FSH), prolactin, testosterone and estradiol. Vitamin A concentration in serum was also measured. Presence of heavy metal was investigated by elemental electron microscopy in seminal cells (eight cases) & by spectrometry in serum as well as seminal plasma.

RESULTS

Chromosomal and Yq microdeletion study failed to detect any abnormalities. AMH, inhibin B and vitamin A were also normal. Estradiol level was high in 6 out of 13 cases (46%) while platinum in seminal cells was high in 4 cases (50%). High (four times or more) serum level of lead and nickel was observed in 11 (85%) and 6 (46%) cases, respectively.

CONCLUSION

High serum concentration of heavy metals like lead & nickel or high platinum accumulation in seminal cells or high serum estradiol alone or in combinations may be underlying aetiologic factors in human spermiation defect.

Management options for stage I seminoma

Stage I seminoma is the most common clinical scenario among patients with testicular cancer. Following orchiectomy, various treatment alternatives (adjuvant radiotherapy, surveillance, chemotherapy) can be offered that yield similar efficacy results and definitive cure is the rule. However, there is no consensus on the optimal management choice and considerable debate has been raised in recent years. The pros and the cons associated with each therapy, as well as their long-term outcomes are discussed in this review. Overall burden of treatment needed, therapy-related morbidity, economic costs, quality of life issues and patient preferences should all be considered. Refinement in the knowledge of predictive factors for relapse and mounting experience with both surveillance and adjuvant chemotherapy have led to consideration of risk-adapted treatment strategies as an alternative to standard radiotherapy. Although this model needs to be improved and validated, active close surveillance for low-risk patients and adjuvant therapy for those uncompliant or at higher risk of relapse seem to be acceptable options for patients with stage I seminoma.

No correlation between germline mutation at repeat DNA and meiotic crossover in male mice exposed to X-rays or cisplatin

To test the hypothesis that mouse germline expanded simple tandem repeat (ESTR) mutations are associated with recombination events during spermatogenesis, crossover frequencies were compared with germline mutation rates at ESTR loci in male mice acutely exposed to 1Gy of X-rays or to 10mg/kg of the anticancer drug cisplatin. Ionising radiation resulted in a highly significant 2.7-3.6-fold increase in ESTR mutation rate in males mated 4, 5 and 6 weeks after exposure, but not 3 weeks after exposure. In contrast, irradiation had no effect on meiotic crossover frequencies assayed on six chromosomes using 25 polymorphic microsatellite loci spaced at approximately 20cM intervals and covering 421cM of the mouse genome. Paternal exposure to cisplatin did not affect either ESTR mutation rates or crossover frequencies, despite a report that cisplatin can increase crossover frequency in mice. Correlation analysis did not reveal any associations between the paternal ESTR mutation rate and crossover frequency in unexposed males and in those exposed to X-rays or cisplatin. This study does not, therefore, support the hypothesis that mutation induction at mouse ESTR loci results from a general genome-wide increase in meiotic recombination rate.

Adjuvant treatment of clinical stage I seminoma: is a single course of carboplatin sufficient?

OBJECTIVES

Adjuvant radiotherapy produces excellent disease-free rates in clinical Stage I seminoma. However, concern is growing about side effects and late hazards of this treatment. Carboplatin has been suggested to supplant radiotherapy. To date, there is little experience with this drug in the adjuvant treatment of seminoma. In particular, it is unclear whether one or two courses should be administered.

METHODS

In a nonrandomized study, 125 patients with pure clinical Stage I seminoma were given adjuvant carboplatin treatment (400 mg/m2). Ninety-three patients received one course and 32 two courses. The median follow-up time was 48 months. To assess gonadal toxicity, serial measurements of follicle-stimulating hormone (FSH) levels were done. To assess myelotoxicity, platelet counts at 3 and 4 weeks after treatment were monitored.

RESULTS

There were no relapses after two courses of carboplatin. After one course of carboplatin, eight relapses occurred (8.6%; 95% confidence interval [CI] 3.79% to 16.2%). All the relapses were located in the para-aortic region, and all the patients were rescued with cisplatin-based chemotherapy. The median time to recurrence was 16 months. The 5-year actuarial progression-free survival rate after one course was 91.1% (95% CI 85.25% to 97.01%). Younger patients (age groups: less than 30 years and 31 to 38 years) had relapses more frequently (P = 0.038) than those in the older age group (greater than 38 years). After 3 weeks, 32% of the patients had platelet counts below 150/nL. The median FSH level increased immediately after treatment, reaching a peak of 13.6 U/L. After 20 months, the median FSH level had returned to the normal range.

CONCLUSIONS

One adjuvant course of carboplatin was associated with low myelotoxicity and low gonadal toxicity; however, the recurrence rate was almost 9% and thus unsatisfactory. After two courses of carboplatin, no relapse was observed. Thus, the two-course regimen of carboplatin appears to be equivalent to radiotherapy, and because of its favorable toxicity profile, this regimen should be investigated in randomized trials.