An update on emerging drugs for the treatment of erectile dysfunction

Safety and efficacy of platelet-rich plasma injection for treatment of erectile dysfunction: a prospective randomized controlled study

BACKGROUND

Affected sexual relationships affect both the quality of life of men and women. Platelet-derived therapies are becoming increasingly popular in various medical and surgical fields because of their ability to aid in tissue healing and vascular remodeling. This study aimed to assess the safety and effectiveness of platelet-rich plasma (PRP) injections in treating patients with erectile dysfunction (ED).

RESULTS

Fifty-two participants with mild to moderate ED were divided into two groups: group A, who received three PRP penile injections, and group B, who received three saline injections (5 ml for each injection site). The International Index of Erectile Function (IIEF) was used to evaluate all participants. A month after the last injection, the PRP group's IIEF was 16.12 ± 1.25, while the placebo group's was 15.99 ± 1.21 (p = 0.683). Following a 3-month period, the IIEF for the PRP group was 16.44 ± 1.17, while the placebo group's was 16.31 ± 1.06 (p value = 0.653). Following a 6-month period, the IIEF for the PRP group was 16.35 ± 1.45, while that for the placebo group's was 16.23 ± 1.19 (p = 0.727). In terms of IIEF, there was no significant difference between the two groups after one, three, and six months of treatment.

CONCLUSION

In brief, our research revealed no data to support the application of PRP injections in the management of mild-to-moderate ED.

Riluzole, a neuroprotective agent, preserves erectile function following bilateral cavernous nerve injury in male rats

Neurogenic erectile dysfunction is a highly prevalent complication in men undergoing radical prostatectomy. The underlying mechanisms remain incompletely defined and the effective therapy has been limited. This study aimed to evaluate the protective effect of riluzole and the role of PKC β and excitatory amino acid transporters (EAATs) mediating this effect in a rat model of bilateral cavernous injury (BCNI). A total of 48 male Sprague-Dawley rats were divided into sham, BCNI (at 7, 15 days post-injury) and BCNI treated with riluzole (8 mg/kg/day) groups. Erectile function was measured as maximum intracavernosal pressure (mICP)/mean arterial pressure (MAP) and total ICP/MAP. Changes in protein expressions of phospho (p)-PKC β IIser660 and EAATs were analysed in penis and major pelvic ganglion with western blotting. BCNI decreased erectile function at 7 and 15 days post-injury (mICP/MAP at 4 V: 0.45 ± 0.06 vs 0.84 ± 0.07; 0.34 ± 0.04 vs 0.77 ± 0.04 respectively; p < 0.001) whereas riluzole treatment (for 15 days) preserved erectile function (mICP/MAP at 4 V: 0.62 ± 0.03 vs 0.34 ± 0.04; p < 0.01). The decline in the expression of p-PKC β IIser660 was observed in penis at 7 and 15 days post-injury (p = 0.0003, p = 0.0033), which was prevented by riluzole treatment for 15 days (p = 0.0464). While expressions of EAAT-1 and EAAT-2 decreased in major pelvic ganglion following BCNI (p = 0.0428, p = 0.002), riluzole treatment for 15 days prevented the decrease only in EAAT-2 expression (p = 0.0456). Riluzole improved erectile function via possibly interacting with PKC β II and glutamatergic pathways, as a potential therapeutic candidate for erectile dysfunction.

Oral phosphodiesterase type 5 inhibitors and priapism: A VigiBase analysis

PURPOSE

To explore the differences of priapism events among a diverse cohort taking erectogenic medicines (i.e., phosphodiesterase type 5 inhibitors [PDE5i] and intracavernousal drugs).

METHODS

We queried the World Health Organization global database of individual case safety reports (VigiBase) for records of the adverse drug reactions (ADR) with sildenafil, tadalafil, avanafil, vardenafil, papaverine, and alprostadil. Disproportionality analyses (case/non-case approach) were performed to assess the reporting odds ratio (ROR) of priapism reporting in PDE5i consumers compared to intracavernousal drug recipients.

RESULTS

From a total of 133 819 ADR events for erectogenic medications, 632 were priapism (PDE5is: n = 550, 0.41%; intracavernousal drugs: n = 82, 9.92%). Priapism disproportionality signals from intracavernousal drugs were 25 times stronger than PDE5is (ROR = 34.7; confidence interval [CI] 95%: 27.12-43.94 vs. ROR = 1.38; 95% CI: 1.24-1.54). For all PDE5i agents, the 12-17 years age group had the highest ROR (9.49, 95% CI: 3.76-19.93) followed by 2-11 years (4.31, 95% CI: 1.57-9.4). Disproportionality signals for consumers under 18 for both all PDE5is as a whole (ROR = 4.57, 95% CI: 2.48-7.73) and sildenafil (ROR = 4.89, 95% CI: 2.51-8.62) were stronger than individuals 18 or older (ROR = 1.06, 95% CI: 0.93-1.21 and ROR = 1.08, 95% CI: 0.91-1.26, respectively).

CONCLUSIONS

PDE5i use shows disproportionate priapism signals which are higher in young patients.

Functional recovery of injured cavernous nerves achieved through endogenous nerve growth factor-containing bioactive fibrous membrane

Radical prostatectomy is a highly successful treatment for prostate cancer, among the most prevalent manifestations of the illness. Damage of the cavernous nerve (CN) during prostatectomy is the main cause of postoperative erectile dysfunction (ED). In this study, the capability of a personalized bioactive fibrous membrane to regenerate injured CN was investigated. The fibrous membrane bioactivity is conferred by the selectively bound nerve growth factor (NGF) present in the rat urine. In a rat model of bilateral CN crush, the implanted bioactive fibrous membrane induces CN regeneration and restoration of erectile function, showing a significantly increased number of smooth muscle cells and content of endothelial and neuronal nitric oxide synthases (eNOS; nNOS). In addition, the bioactive fibrous membrane promotes nerve regeneration by increasing the number of myelinated axons and nNOS-positive cells, therefore reversing the CN fibrosis found in untreated rats or rats treated with a bare fibrous membrane. Therefore, this personalized regenerative strategy could overcome the recognized drawbacks of currently available treatments for CN injuries. It may constitute an effective treatment for prostate cancer patients suffering from ED after being subject to radical prostatectomy. STATEMENT OF SIGNIFICANCE: The present work introduces a unique strategy to address post-surgical ED resulting from CN injury during pelvic surgery (e.g., radical prostatectomy, radical cystoprostatectomy, abdominoperineal resection). It comprises a bioactive and cell-free fibrous implant, customized to enhance CN recovery. Pre-clinical results in a rat model of bilateral CN crush demonstrated that the bioactive fibrous implant can effectively heal injured CN, and restore penile structure and function. This implant selectively binds NGF from patient fluids (i.e. urine) due to its functionalized surface and high surface area. Moreover, its local implantation reduces adverse side effects. This tailored regenerative approach has the potential to revolutionize the treatment of ED in prostate cancer patients following radical prostatectomy, overcoming current treatment limitations.

Smoking status and the baseline international index of erectile function score can predict satisfactory response to platelet-rich plasma in patients with erectile dysfunction: A prospective pilot study

Erectile dysfunction (ED) is a common condition with a significant impact on the quality of life. Regenerative medicine maladies are intended to repair or replace damaged tissues and organs through different therapeutic mechanisms. Our aim was to study the effect of intra-corporeal injection (ICI) of platelet-rich plasma (PRP) in ED patients. Thirty-four patients' erectile function was evaluated by filling up an abridged form of the international index of erectile function (IIEF-5) before and after PRP therapy. ICI of PRP was done once per week for 2 months. All patients were prescribed PDE5Is for one month after PRP therapy. Penile haemodynamics was assessed using 20 µg of PGE1 before and 3 months after initiating PRP therapy. Interestingly, our study had shown that there was a statistically significant difference in the IIEF-5 score after ICI of PRP (-5.5, ±5.2, p=<0.001). Furthermore, in multiple logistic regression model for PRP responsiveness, smoking and IIEF score before PRP were the only significant independent variables (p = .040, p = .023 respectively). PRP injection for ED patients may be a promising modality as well as baseline IIEF-5, and smoking status can be used as predictors for a satisfactory response to PRP in such patients.

Evaluation of immediate and short-term efficacy of DualStim therapy with and without intracavernosal umbilical cord-derived Wharton's jelly in patients with erectile dysfunction: Study protocol for a randomized controlled trial

Introduction

Erectile dysfunction (ED) affects a significant portion of the United States population and causes negative psychological burdens that affects men and their partner's quality of life and satisfaction. Extracorporeal shock therapy (ESWT) utilizing focused ESWT and radial ESWT in Low-intensity shock wave therapy has been used to treat ED with some success. Wharton's Jelly (WJ) is a biologic substance with large amounts of stem cells, growth factors, cytokines and extracellular components. The use of combined focused and radial ESWT (DualStim therapy) with injected WJ have potential uses in ED that may have advantages over current treatments.

Materials

A randomized, single-blinded, controlled clinical trial will be conducted to evaluate the efficacy and safety of DualStim therapy and intracavernosal injection of WJ in moderate to severe ED. A total of 60 patients with moderate to severe ED will be enrolled and treated with DualStim therapy with intracavernosal injection of WJ or saline for a period of 7 weeks. The International Index of Erectile Function – Erectile Function score will be used to gauge the treatment related changes in relation to the subject's baseline. The scores will be recorded at baseline and compared to follow-ups 1,3 and 6 months post-treatment. Any adverse events or severe adverse events will be recorded in the corresponding case report forms. Sexual Encounter Profile, as well as the Global Assessment Questionnaire and the Erection Hardness Score will be used to determine the sexual activity improvement from baseline leading to optimal penetration at follow-ups 1,3 and 6 months post-treatment.

Discussion

This clinical trial is one of the first studies to determine the immediate and short-term efficacy of DualStim therapy, with and without intracavernosal injection of formulated umbilical cord-derived WJ to improve and/or restore erectile function in patients with moderate to severe ED. This study will also provide insight into the safety and efficacy of WJ. We anticipate clinically significant improvement in patients suffering from moderate and severe ED treated with DualStim therapy with WJ compared to their baseline and DualStim with saline.

Early Clinical Results of the Tolerability, Safety, and Efficacy of Autologous Platelet-Rich Plasma Administration in Erectile Dysfunction

Introduction

Platelet-rich plasma (PRP) is useful in the treatment of different conditions and diseases as it contains concentrated levels of many growth factors.

Aim

The aim of this study was to investigate the effectiveness of autologous PRP application in the treatment of erectile dysfunction (ED) in patients with metabolic syndrome.

Methods

In this prospective study conducted in June 2019, 31 patients with ED were included. The International Index of Erectile Function–Erectile Function domain (IIEF-EF) questionnaires were used to evaluate erectile function (EF). After administering the intracavernous autologous PRP 3 times with an interval of 15 days, IIEF-EFs were evaluated 1, 3, and 6 months later.

Main Outcome Measure

IIEF in the 1st, 3rd, and 6th months and adverse events.

Results

While the mean IIEF-EF was 18 before the application, the mean IIEF-EF was 20 in the first, third, and sixth months after the procedure (P < .001). However, even though IIEF-EF values increased numerically, median value remained within the mild-moderate classification (scores between 17 and 21). Postprocedure sexual satisfaction scores were significantly higher than preprocedure values (8 vs 6, respectively; P = .002). In the first follow-up of a patient after the 3rd injection, a 4-mm diameter fibrotic plaque was observed on the ventral side in the middle of the penis shaft.

Conclusion

In conclusion, our findings suggest that larger studies as well as placebo-controlled studies are needed to add PRP to the treatment protocol in ED.

T Taş,Çakıroğlu, E Arda, et al. Early Clinical Results of the Tolerability, Safety, and Efficacy of Autologous Platelet-Rich Plasma Administration in Erectile Dysfunction. Sex Med 2021;9:100313.

Thinking About Pathomechanisms and Current Treatment of Erectile Dysfunction-"The Stanley Beamish Problem." Review, Recommendations, and Proposals

INTRODUCTION

Up to 50% of all men over 50 years of age suffer from erectile dysfunction. Since the late 1990s erectile dysfunction has been treated mostly with phosphodiesterase 5 inhibitors (PDE5I). Over the past 20 years, numerous scientific findings on the development of erectile dysfunction have been collected, which have so far received little attention in the treatment of erectile dysfunction.

OBJECTIVES

The objectives of this study were to review the existing medical literature on erectile dysfunction regarding physiology, pathophysiology, and especially therapeutic options beyond treatment with PDE5I and to enable a more effective and especially sustainable treatment for erectile dysfunction.

METHODS

A literature review was performed by using PubMed from 1985 to 2020 regarding the physiology, pathophysiology, and treatment of erectile dysfunction.

RESULTS

Since the end of the 1990s an enormous amount of knowledge has been gained about the physiology/pathophysiology of erection/erectile dysfunction. Based on these findings, numerous physical, drug, and holistic therapeutic options (beyond the application of PDE5I) have been developed for the treatment of erectile dysfunction. However, these are still relatively rarely used in the therapeutic concept of erectile dysfunction today.

CONCLUSION

Based on scientific findings of the last 20 years, there are numerous therapeutic approaches, including lifestyle modification, specific pelvic floor exercises, shock wave treatment, and the application of different supplements. The long-term treatment of erectile dysfunction should now go beyond the purely symptomatic use of PDE5I. W-D Beecken, M Kersting, W Kunert, et al. Thinking About Pathomechanisms and Current Treatment of Erectile Dysfunction-"The Stanley Beamish Problem." Review, Recommendations, and Proposals. Sex Med Rev 2021;9:445-463.

Practical Approaches to Treat ED in PDE5i Nonresponders

Erectile dysfunction (ED) is a common sexual disorder in adult males and one of the most important factors affecting their quality of life and that of their partners. Although PDE5 inhibitors (PDE5is) are the first choice for improving erectile function, there is a substantial proportion of ED patients, termed PDE5i nonresponders, who do not respond to PDE5is. Because of the lack of effective therapies, these patients always have serious social and psychological problems due to ED, which should be addressed. Here, we review the available literature about ED and PDE5is and propose several strategies for mitigating ED in PDE5i nonresponders.

Novel Emerging Therapies for Erectile Dysfunction

Currently, several treatments exist for the improvement of erectile dysfunction (ED). These include medical therapies such as phosphodiesterase type 5 inhibitors (PDE5-Is), invasive methods such as intracavernosal injection therapy of vaso-active substances, vacuum erection devices, and penile prosthesis implants. However, the percentage of patients that are unresponsive to available treatments and who drop out from treatments remains high. Current evidence reveals that the pathogenesis of ED is related to multiple factors including underlying comorbidities, previous surgery, and psychological factors. Diverse approaches using novel molecular pathways or new technologies have been tested as potential therapeutic options for difficultto-treat ED populations. Melanocortin receptor agonist, a centrally acting agent, showed promising results by initiating erection without sexual stimulation in non-responders to PDE5-Is. Recent clinical and pre-clinical studies using human tissues suggested that new peripherally acting agents including the Max-K channel activator, guanylate cyclase activator, and nitric oxide donor could be potential therapies either as a monotherapy or in combination with PDE5-Is in ED patients. According to several clinical trials, regeneration therapy using stem cells showed favorable data in men with diabetic or post-prostatectomy ED. Low-intensity shock wave therapy also demonstrated promising results in patients with vasculogenic ED. There are growing evidences which suggest the efficacy of these emerging therapies, though most of the therapies still need to be validated by well-designed clinical trials. It is expected that, should their long-term safety and efficacy be proven, the emerging treatments can meet the needs of patients hitherto unresponsive to or unsatisfied by current therapies for ED.

The good, bad, and the ugly of regenerative therapies for erectile dysfunction

Erectile dysfunction (ED) is a common condition which reduces quality of life of both patients and their partners, and is a significant health care expense every year. Although phosphodiesterase type-5 inhibitors are the current first-line treatment for men with ED, they are limited by their on-demand dosing, intolerance, and variable efficacy in complex patient populations such as men with multiple medical comorbidities or ED after pelvic surgery. Regenerative medicine has been introduced and investigated in andrology as an encouraging strategy to restore diseased erectile tissue structure and function. Novel regenerative therapies for ED are controversial but are perceived to offer a durable and safe tissue restorative approach to act as a long-term solution to this cumbersome disease process. Here, we review platelet-rich plasma, amniotic fluid membranes, low-intensity extracorporeal shockwave therapy, and stem cell therapy as regenerative strategies to treat ED. Most of these approaches have preclinical and occasionally clinical data to support their ongoing investigation; however, none of these treatments are currently supported for use in ED patients outside of clinical trials.

Evolving therapies for Peyronie's disease: how can we work towards new drugs?

Peyronie's disease (PD) is an idiopathic chronic fibrotic disease that causes a penile curvature (PC), subsequent erectile dysfunction (ED) and impaired sexual intercourse in patients. As of yet, there are no reliable non-surgical treatment options available. Intralesional injection with collagenase Clostridum Histolyticum has been FDA approved since 2013, but post-approval studies have not been unanimously positive. Moreover, it renders a curvature improvement of only 30% on average, usually still requiring surgical intervention to remedy PC. Therefore, there is a need for drugs which could prevent surgery altogether. Development of new drugs can either be through a target-based or phenotypic assay-based approach. The current in vivo model for PD is dependent on treatment of primary PD-derived fibroblasts with transforming growth factor-β1. Moreover, despite the existence of a genetic in vivo PD model, it does not allow for drug screening or testing. While some advances have been made in the past few years, new in vivo and in vivo systems and well-designed studies are urgently needed for the non-surgical treatment of PD.

Simvastatin and the Rho-kinase inhibitor Y-27632 prevent myofibroblast transformation in Peyronie's disease-derived fibroblasts via inhibition of YAP/TAZ nuclear translocation

OBJECTIVES

To uncover the anti-myofibroblast (MFB) properties of Rho-kinase inhibitor (compound Y-27632) and simvastatin in an in vitro model of Peyronie's disease (PD), a sexually debilitating disease caused by an irreversible fibrotic plaque in the penile tunica albuginea (TA).

MATERIALS AND METHODS

Primary human fibroblasts (FBs) were isolated from surgically obtained TA tissue from patients with PD. To induce MFB status, cells were stimulated with 3 ng/mL transforming growth factor-β1 (TGF-β1). Increasing doses of Y-27632 and simvastatin were added. Real-time quantitative PCR was used to assess mRNA expression of α-smooth muscle actin (α-SMA), collagen III, elastin and connective tissue growth factor (CTGF) after 72 h. Western blot analysis was used to quantify α-SMA protein contents, and immunofluorescence (IF) was used to visualize MFB differentiation by staining for α-SMA after 72 h. A resazurin-based assay was used to assess cell viability to ensure the anti-MFB effect of the drugs. A mechanistic study was performed using IF staining for YAP/TAZ nuclear translocation.

RESULTS

After 72 h of stimulation with TGF-β1, a six- to 10-fold upregulation of α-SMA could be observed. When treated with Y-27632 or simvastatin, the α-SMA, collagen III, elastin and CTGF mRNA expression was impeded. Additionally, TGF-β1 stimulation showed a twofold increase in α-SMA protein expression, which was reversed to non-stimulated levels after treatment with Y-27632 and simvastatin. Using IF, stimulated cells were identified as MFB (α-SMA+, Vim+) as opposed to the non-stimulated, Y-27632- and simvastatin-treated cells (α-SMA-, Vim+). The resazurin-based assay confirmed that the cell viability was not compromised by the administered drugs. On stimulation with TGF-β1, nuclear translocation of YAP/TAZ could be observed, which was prevented by adding the aforementioned compounds.

CONCLUSION

Transformation of FBs into the contractile and extracellular matrix-producing MFBs occurs after TGF-β1 stimulation. In our experiments, Rho-kinase inhibition and simvastatin treatment were shown to prevent this in TGF-β1-stimulated cells on an RNA and protein level through the inhibition of YAP/TAZ nuclear translocation. Y-27632 and simvastatin could become a novel treatment option in the early treatment of PD.