What should be next in lifelong posterior hypospadias: Conclusions from the 2023 ERN eUROGEN and EJP-RD networking meeting.

BACKGROUND: A congenital disease is for life. Posterior hypospadias, the severe form of hypospadias with a penoscrotal, scrotal, or perineal meatus, is a challenging condition with a major impact on lifelong quality of life. AIM: Our network meeting is aimed to identify what is currently missing in the lifelong treatment of posterior hypospadias, to improve care, quality of life, and awareness for these patients. METHODS: The network meeting "Lifelong Posterior Hypospadias" in Utrecht, The Netherlands was granted by the European Joint Programme on Rare Diseases-Networking Support Scheme. There was a combination of interactive sessions (hackathons) and lectures. This paper can be regarded as the last phase of the hackathon. RESULTS: Surgery for hypospadias remains challenging and complications may occur until adulthood. Posterior hypospadias affects sexual function, fertility, and hormonal status. Transitional care from childhood into adulthood is currently insufficiently established. Patients should be more involved in defining desired treatment approach and outcome measures. For optimal outcome evaluation standardization of data collection and registration at European level is necessary. Tissue engineering may provide a solution to the shortage of healthy tissue in posterior hypospadias. For optimal results, cooperation between basic researchers from different centers, as well as involving clinicians and patients is necessary. CONCLUSIONS: To improve outcomes for patients with posterior hypospadias, patient voices should be included and lifelong care by dedicated healthcare professionals guaranteed. Other requirements are joining forces at European level in uniform registration of outcome data and cooperation in basic research.

Intravesical botulinum-A toxin in children with refractory non-neurogenic overactive bladder.

INTRODUCTION: Overactive bladder (OAB) with urinary incontinence poses a potentially significant impact on daily activities and quality of life. OAB can be unresponsive to specific urotherapy and antispasmodic medication. Due to its successful outcomes in the treatment of neurogenic bladder, intravesical botulinum-A toxin (BTX-A) became a possible solution for children refractory to treatment. OBJECTIVE: To analyse the outcomes of intravesical BTX-A injections on bladder volume and incontinence in children with refractory OAB. STUDY DESIGN: The charts of children diagnosed with refractory non-neurogenic OAB who underwent BTX-A treatment in our centre since 2011 were retrospectively analysed. The functional bladder volume (FBV) is expressed as a percentage of the expected bladder capacity (EBC) for age. Dependent variables were compared using the Wilcoxon Signed Rank test. A multivariate logistic regression was used to identify predictors of the response on urinary incontinence. RESULTS: Fifty children (41 boys) with a median age of 9.9 years were included. In the short term, there was a significant increase in FBV after initial BTX-A treatment from a median of 52.9%-70% (p = 0.000). In the short (<6 months) and long term (6-12 months) 72% and 46% showed improvement of continence, respectively. Male gender and small baseline FBV predict a positive outcome on continence in the long term. The most prevalent complications were urinary tract infections occurring in five cases (10%). DISCUSSION: Although BTX-A injections serve as an effective therapy to increase bladder volume in non-neurogenic OAB children, the outcomes on urinary incontinence are highly variable. This may be a consequence of the multifactorial aspects of this condition. BTX-A will enable children to inhibit their bladder urgency. The effectiveness of post-BTX-A urotherapy training will therefore most probably be higher. We believe that BTX-A injections should be reserved for children refractory to both specific urotherapy and medication. An appropriate population seems to be children with severe OAB symptoms, confirmed detrusor overactivity in urodynamic study and reduced bladder volume. CONCLUSION: In refractory OAB children, BTX-A injections are safe and effective in enlarging bladder volume and reducing OAB symptoms, particularly in the first six months after injection.

Daytime urinary incontinence in children and adolescents.

Daytime urinary incontinence is common in the paediatric population and affects approximately 7-10% of children (aged 5-13 years). Several subtypes of daytime incontinence, which are classified according to their relation to the storage and voiding phases of bladder function, exist. Risk factors for these subtypes of incontinence can be genetic, demographic, environmental, behavioural, or physical. Therefore, treatment is multidisciplinary and needs an adequate diagnosis to be successful. Urotherapy is the first-line treatment for all types of daytime incontinence. It can be defined as bladder re-education or rehabilitation, aiming at correcting the filling and voiding function of the bladder-sphincter unit. Comorbid problems, such as constipation, urinary tract infections, and behavioural problems should also be treated during urotherapy. For comorbidities and severe bladder overactivity, medication might be necessary. Although usually effective, treatment of daytime urinary incontinence in children is often complex and requires patience. Nonetheless, patients and parents are usually motivated for urotherapy, since quality of life is severely reduced in in children with incontinence.

Gastrin-releasing peptide receptor-based targeting using bombesin analogues is superior to metabolism-based targeting using choline for in vivo imaging of human prostate cancer xenografts.

PURPOSE: Prostate cancer (PC) is a major health problem. Overexpression of the gastrin-releasing peptide receptor (GRPR) in PC, but not in the hyperplastic prostate, provides a promising target for staging and monitoring of PC. Based on the assumption that cancer cells have increased metabolic activity, metabolism-based tracers are also being used for PC imaging. We compared GRPR-based targeting using the (68)Ga-labelled bombesin analogue AMBA with metabolism-based targeting using (18)F-methylcholine ((18)F-FCH) in nude mice bearing human prostate VCaP xenografts. METHODS: PET and biodistribution studies were performed with both (68)Ga-AMBA and (18)F-FCH in all VCaP tumour-bearing mice, with PC-3 tumour-bearing mice as reference. Scanning started immediately after injection. Dynamic PET scans were reconstructed and analysed quantitatively. Biodistribution of tracers and tissue uptake was expressed as percent of injected dose per gram tissue (%ID/g). RESULTS: All tumours were clearly visualized using (68)Ga-AMBA. (18)F-FCH showed significantly less contrast due to poor tumour-to-background ratios. Quantitative PET analyses showed fast tumour uptake and high retention for both tracers. VCaP tumour uptake values determined from PET at steady-state were 6.7 ± 1.4%ID/g (20-30 min after injection, N = 8) for (68)Ga-AMBA and 1.6 ± 0.5%ID/g (10-20 min after injection, N = 8) for (18)F-FCH, which were significantly different (p <0.001). The results in PC-3 tumour-bearing mice were comparable. Biodistribution data were in accordance with the PET results showing VCaP tumour uptake values of 9.5 ± 4.8%ID/g (N = 8) for (68)Ga-AMBA and 2.1 ± 0.4%ID/g (N = 8) for (18)F-FCH. Apart from the GRPR-expressing organs, uptake in all organs was lower for (68)Ga-AMBA than for (18)F-FCH. CONCLUSION: Tumour uptake of (68)Ga-AMBA was higher while overall background activity was lower than observed for (18)F-FCH in the same PC-bearing mice. These results suggest that peptide receptor-based targeting using the bombesin analogue AMBA is superior to metabolism-based targeting using choline for scintigraphy of PC.

A standardised study to compare prostate cancer targeting efficacy of five radiolabelled bombesin analogues.

PURPOSE: Prostate-specific antigen (PSA)-based screening for prostate cancer (PC) has dramatically increased early diagnosis. Current imaging techniques are not optimal to stage early PC adequately. A promising alternative to PC imaging is peptide-based scintigraphy using radiolabelled bombesin (BN) analogues that bind to gastrin-releasing peptide receptors (GRPR) being overexpressed in PC. When labelled to appropriate radionuclides BN targeting of GRPRs may also provide applications for peptide radionuclide receptor therapy (PRRT). Assessment studies under identical experimental conditions allowing a reliable comparison of the potential of such analogues are lacking. This study was performed to evaluate and directly compare five promising radiolabelled BN analogues for their targeting efficacy for PC under standardised conditions. METHODS: The BN agonists [(111)In]DOTA-PESIN, [(111)In]AMBA, [(111)In]MP2346 and [(111)In]MP2653 and one antagonist [(99m)Tc]Demobesin-1 were evaluated in GRPR-overexpressing human PC-3 tumour-bearing mice to determine peptide stability in vivo, biodistribution and GRPR targeting potential by animal SPECT/CT imaging and ex vivo autoradiography. RESULTS: HPLC analysis of blood showed intact Demobesin-1 at 5 and 15 min after injection (64.1 +/- 1.6% and 41.0 +/- 01%, respectively) being much less for the other compounds. AMBA, the second most stable analogue, showed 36.1 +/- 2.7% and 9.8 +/- 1.1% intact peptide after 5 and 15 min. PC-3 tumour uptake at 1 h was comparable for Demobesin-1, AMBA, PESIN and MP2346 (3.0 +/- 0.4, 2.7 +/- 0.5, 2.3 +/- 0.5 and 2.1 +/- 0.9%ID/g, respectively), but very low for MP2653 (0.9 +/- 0.2%ID/g). In addition, MP2346 showed undesirably high uptake in the kidneys (7.9 +/- 1.9%ID/g) being significantly less for the other analogues. AMBA, MP2346 and PESIN revealed favourable increases in tumour to blood ratios over time while changes in tumour to kidney and pancreas ratios for Demobesin-1 from 1 to 24 h after injection were significantly better than for the other analogues. All analogues visualised PC-3 tumours by SPECT/CT and autoradiography. CONCLUSION: In the present study the BN antagonist Demobesin-1 was the best performing analogue showing superior in vivo stability, highest tumour uptake and retention while pancreatic and renal clearance were rapid. PESIN and AMBA were the best GRP agonists with sufficient in vivo stabilities as well as high tumour uptake and retention. Based on these results all three analogues deserve further evaluation for clinical use in PC patients.

Androgen-regulated gastrin-releasing peptide receptor expression in androgen-dependent human prostate tumor xenografts.

Human prostate cancer (PC) overexpresses the gastrin-releasing peptide receptor (GRPR). Radiolabeled GRPR-targeting analogs of bombesin (BN) have successfully been introduced as potential tracers for visualization and treatment of GRPR-overexpressing tumors. A previous study showed GRPR-mediated binding of radiolabeled BN analogs in androgen-dependent but not in androgen-independent xenografts representing the more advanced stages of PC. We have further investigated the effect of androgen modulation on GRPR-expression in three androgen-dependent human PC-bearing xenografts: PC295, PC310 and PC82 using the androgen-independent PC3-model as a reference. Effects of androgen regulation on GRPR expression were initially studied on tumors obtained from our biorepository of xenograft tissues performing reverse transcriptase polymerase chain reaction (RT-PCR) and autoradiography ((125)I-universal-BN). A prospective biodistribution study ((111)In-MP2653) and subsequent autoradiography ((125)I-GRP and (111)In-MP2248) was than performed in castrated and testosterone resupplemented tumor-bearing mice. For all androgen-dependent xenografts, tumor uptake and binding decreased drastically after 7 days of castration. Resupplementation of testosterone to castrated animals restored GRPR expression extensively. Similar findings were concluded from the initial autoradiography and RT-PCR studies. Results from RT-PCR, for which human specific primers are used, indicate that variations in GRPR expression can be ascribed to mRNA downregulation and not to castration-induced reduction in the epithelial fraction of the xenograft tumor tissue. In conclusion, expression of human GRPR in androgen-dependent PC xenografts is reduced by androgen ablation and is reversed by restoring the hormonal status of the animals. This knowledge suggests that hormonal therapy may affect GRPR expression in PC tissue making GRPR-based imaging and therapy especially suitable for non-hormonally treated PC patients.