Gonadal development and function after immature testicular tissue banking as part of high-risk gonadotoxic treatment.

Background: Experimental fertility preservation programs have been started to safeguard the future fertility of prepubertal and pubertal males requiring high-risk gonadotoxic treatment protocols. However, long-term follow-up studies evaluating the effects on their gonadal development and function related to the testicular biopsy procedure are rather limited.

Design: This two-center follow-up study (between 2002 and 2020) evaluated the gonadal development and function of a cohort of 59 prepubertal and pubertal males who have been offered immature testicular tissue banking (TTB) prior to conventional high-risk chemo- and/or radiotherapy (HR-C/R) or conditioning therapy before hematopoietic stem cell transplantation (CT-HSCT). The aim is to investigate the long-term impact of the testicular biopsy procedure and the high-risk gonadotoxic treatment. Testicular growth and the reproductive hormones luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), and inhibin B (INHB) were analyzed after treatment completion, and compared between males accepting TTB and those refusing TTB (control) as well as between HR-C/R and CT-HSCT treatment protocols.

Results: Of the 59 prepubertal and pubertal males included, 25 were treated by HR-C/R and 34 required CT-HSCT. TTB was accepted for 39 males and refused for 20 males. Most patients were prepubertal at diagnosis (85%), at TTB (79%), and at treatment completion (76%), and pubertal or postpubertal at their last follow-up visit (66%). After 5.0 (1.0-13.0) years post treatment, most patients show normal testicular volumes (83%) and normal LH (89%), FSH (87%), T (87%), and INHB (79%) serum levels. The testicular biopsy procedure did not have an effect on testicular growth, LH, FSH, T, and INHB. Significantly more small postpubertal testicular volumes (p = .0278) and low INHB serum levels (p = .0130) were recorded after CT-HSCT, especially after myeloablative conditioning.

Conclusion: The clinical follow-up data demonstrate no effect related to the biopsy procedure, but a substantial risk for impaired gonadal development after high-risk gonadotoxic treatment, in particular myeloablative CT-HSCT. Longer follow-up studies with a larger study population are needed to confirm these preliminary findings.