Into the Light: Afamelanotide and the Treatment of Erythropoietic Protoporphyria in the United States

BACKGROUND

Erythropoietic protoporphyria (EPP) is a rare disease that causes disabling cutaneous photosensitivity with pain and burning sensations. In 2019, afamelanotide, an α-melanocyte-stimulating hormone analogue, was approved in the United States for treatment of EPP. In this study, patients receiving afamelanotide filled out questionnaires assessing the benefit of treatment. Outcomes measured included: return to normal activities, experience of phototoxic reactions, effect on patient confidence, and more. Patients ranked their experience on a descriptive scale ranging from "very much" to "never".

RESULTS

Prior to treatment, 75% of patients indicated that EPP affected their lives "very much" or "a lot". This number fell to 11% after the 1st implant and to 0% after each subsequent implant. The number of patients that willingly ventured outside increased with each subsequent implant.

CONCLUSION

The results of this study clearly show that afamelanotide treatment can dramatically and positively impact the lives of EPP patients.  Citation: Resnik SR, Targett D, Resnik BI. Into the light: afamelanotide and the treatment of erythropoietic protoporphyria in the United States. J Drugs Dermatol. 2023;22(9):941-949. doi:10.36849/JDD.7126R1.

Effect of bremelanotide on body weight of obese women: Data from two phase 1 randomized controlled trials

AIMS

The melanocortin 4 receptor (MC4R) plays a central role in appetite regulation, and agonistic activity at this receptor promotes satiety. Results from two randomized controlled clinical trials examine the effects of bremelanotide's agonism at MC4R on caloric intake and body weight.

METHODS

Premenopausal women with a body mass index >30 kg/m² were studied in two phase 1, single-centre, randomized, double-blind, placebo-controlled trials. Study A matched subjects 1:1 to receive subcutaneous placebo or bremelanotide three times daily for days 1-15. Study B was a crossover trial with six distinct treatment sequences consisting of three 4-day treatment periods, investigating once-a-day and twice-a-day exposure to bremelanotide versus placebo. Subjects received one of the three treatments twice-daily during each period: 0 mg/0 mg, 2.5 mg/0 mg or 2.5 mg/2.0 mg bremelanotide. Body weight and food intake were recorded in detail daily. Adverse events were recorded throughout both studies.

RESULTS

In Study A, 27 of 30 bremelanotide subjects (90.0%) completed the trial and exhibited a significantly greater reduction in body weight after 16 days versus placebo [least squares mean difference (95% CI), -1.3 (-1.9 to -0.8) kg; p < .0001]. Mean caloric intake in bremelanotide subjects was decreased versus placebo, with a magnitude of reduction of approximately 400 kcal/day throughout Study A (p < .01). In Study B, 15 of 27 subjects (55.6%) completed all three phases. Significantly greater reduction of mean body weight occurred in twice-daily bremelanotide subjects versus placebo (1.7 vs. 0.9 kg, respectively, p < .001). Total caloric intake reduction was significantly greater in the bremelanotide groups versus placebo (mean difference range: 398-469 kcal; p < .0001).

CONCLUSIONS

Agonist activity at the MC4R may aid in reducing caloric intake and weight loss in obese women.

Afamelanotide: An Orphan Drug with Potential for Broad Dermatologic Applications

Afamelanotide (SCENESSE&reg;) is a synthetic analogue of &alpha;-melanocyte-stimulating hormone that is FDA-approved to increase pain-free sunlight exposure in adult patients with erythropoietic protoporphyria. Its dual photoprotective and anti-inflammatory effects also make it a promising therapy for other photosensitive dermatologic diseases that are resistant to treatment. The PubMed/MEDLINE and ClinicalTrials.gov databases were searched for literature and ongoing trials describing the use of afamelanotide in treating cutaneous diseases. There is randomized controlled trial (RCT) evidence for the successful use of afamelanotide in several conditions beyond erythropoietic protoporphyria, including polymorphic light eruption and vitiligo. Smaller studies have also demonstrated its efficacy in treating acne vulgaris, Hailey-Hailey disease, and solar urticaria. No serious adverse effects with afamelanotide use have been reported, though diffuse hyperpigmentation is experienced by almost all patients. Larger scale studies are needed to confirm the efficacy of afamelanotide in treating dermatologic conditions beyond erythropoietic protoporphyria, and further research should focus on determining the safety, efficacy, and optimal dosing of afamelanotide for pediatric patients.J Drugs Dermatol. 2021;20(3):290-294. doi:10.36849/JDD.5526.

Zerumbone, a Tropical Ginger Sesquiterpene of Zingiber officinale Roscoe, Attenuates α-MSH-Induced Melanogenesis in B16F10 Cells

Zerumbone (ZER), an active constituent of the Zingiberaceae family, has been shown to exhibit several biological activities, such as anti-inflammatory, anti-allergic, anti-microbial, and anti-cancer; however, it has not been studied for anti-melanogenic properties. In the present study, we demonstrate that ZER and Zingiber officinale (ZO) extract significantly attenuate melanin accumulation in α-melanocyte-stimulating hormone (α-MSH)-stimulated mouse melanogenic B16F10 cells. Further, to elucidate the molecular mechanism by which ZER suppresses melanin accumulation, we analyzed the expression of melanogenesis-associated transcription factor, microphthalmia-associated transcription factor (MITF), and its target genes, such as tyrosinase, tyrosinase-related protein 1 (TYRP1), and tyrosinase-related protein 2 (TYRP2), in B16F10 cells that are stimulated by α-MSH. Here, we found that ZER inhibits the MITF-mediated expression of melanogenic genes upon α-MSH stimulation. Additionally, cells treated with different concentrations of zerumbone and ZO showed increased extracellular signal-regulated kinases 1 and 2 (ERK1/2) phosphorylation, which are involved in the degradation mechanism of MITF. Pharmacological inhibition of ERK1/2 using U0126 sufficiently reversed the anti-melanogenic effect of ZER, suggesting that increased phosphorylation of ERK1/2 is required for its anti-melanogenic activity. Taken together, these results suggest that ZER and ZO extract can be used as active ingredients in skin-whitening cosmetics because of their anti-melanogenic effect.

Alpha-melanocyte stimulating hormone-induced anorexia in Japanese quail (Coturnix japonica) likely involves the ventromedial hypothalamus and paraventricular nucleus of the hypothalamus

Alpha-melanocyte stimulating hormone (α-MSH) reduces food intake in birds and mammals. The objective of this experiment was to determine effects of α-MSH on food and water intake, and hypothalamic c-Fos immunoreactivity and appetite-associated factor mRNA in Japanese quail (Coturnix japonica), a species that has not undergone the same artificial selection for growth-related traits as the chicken. At 7days post-hatch, 3-h-fasted quail were intracerebroventricularly (ICV) injected into the lateral ventricle with 0 (vehicle), 0.5, 5, or 50pmol of α-MSH and food and water intake were recorded at 30min intervals for 180min. In the second and third experiment, quail were injected with 50pmol α-MSH and hypothalami were collected at 1h to determine c-Fos immunoreactivity and mRNA abundance, respectively. At 30min, quail injected with 5 or 50pmol of α-MSH ate and drank less than vehicle-injected quail. Quail injected with 50pmol ate less for the entire duration of the experiment and drank less than vehicle-injected quail for 120min post-injection. Hypothalamic expression of agouti-related peptide and DOPA decarboxylase were greater in vehicle- than α-MSH-injected quail, whereas melanocortin receptor 4 (MC4R) mRNA was greater in α-MSH- than vehicle-injected birds. Alpha-MSH injection was associated with more c-Fos immunoreactive cells in the ventromedial hypothalamus (VMH) and paraventricular nucleus (PVN) of the hypothalamus. Results suggest that the anorexigenic effect of α-MSH is conserved among avians and that effects in quail are associated with the VMH and PVN and involve MC4R.

Proopiomelanocortin Deficiency Treated with a Melanocortin-4 Receptor Agonist

Patients with rare defects in the gene encoding proopiomelanocortin (POMC) have extreme early-onset obesity, hyperphagia, hypopigmentation, and hypocortisolism, resulting from the lack of the proopiomelanocortin-derived peptides melanocyte-stimulating hormone and corticotropin. In such patients, adrenal insufficiency must be treated with hydrocortisone early in life. No effective pharmacologic treatments have been available for the hyperphagia and obesity that characterize the condition. In this investigator-initiated, open-label study, two patients with proopiomelanocortin deficiency were treated with setmelanotide, a new melanocortin-4 receptor agonist. The patients had a sustainable reduction in hunger and substantial weight loss (51.0 kg after 42 weeks in Patient 1 and 20.5 kg after 12 weeks in Patient 2).

Afamelanotide: A Review in Erythropoietic Protoporphyria

Afamelanotide (SCENESSE(®)) is a synthetic α-melanocyte stimulating hormone analogue and first-in-class melanocortin-1 receptor agonist that is approved in the EU for the prevention of phototoxicity in adults with erythropoietic protoporphyria (EPP). It is administered subcutaneously as a biodegradable, controlled-release implant containing 16 mg of afamelanotide. This article reviews the clinical efficacy and tolerability of afamelanotide in EPP and summarizes its pharmacological properties. In the phase III trial, CUV039, afamelanotide treatment improved light tolerance in patients with EPP. Compared with placebo, afamelanotide treatment enabled patients to spend more time in direct sunlight without pain and increased the time to the appearance of the first symptoms of phototoxicity provoked by a standardized light source. Afamelanotide was generally well tolerated in this trial, with no drug-related serious adverse events reported. Commonly occurring adverse reactions included headache and implant-site reactions. Efficacy and safety data from earlier phase III trials are consistent with those from the CUV039 trial. Afamelanotide, approved in the EU for the prevention of EPP phototoxicity, represents a useful addition to the management of the disorder.

Afamelanotide for Erythropoietic Protoporphyria

BACKGROUND

Erythropoietic protoporphyria is a severe photodermatosis that is associated with acute phototoxicity. Patients with this condition have excruciating pain and a markedly reduced quality of life. We evaluated the safety and efficacy of an α-melanocyte-stimulating hormone analogue, afamelanotide, to decrease pain and improve quality of life.

METHODS

We conducted two multicenter, randomized, double-blind, placebo-controlled trials of subcutaneous implants containing 16 mg of afamelanotide. Patients in the European Union (74 patients) and the United States (94 patients) were randomly assigned, in a 1:1 ratio, to receive a subcutaneous implant containing either afamelanotide or placebo every 60 days (a total of five implants in the European Union study and three in the U.S study). The type and duration of sun exposure, number and severity of phototoxic reactions, and adverse events were recorded over the respective 180-day and 270-day study periods. Quality of life was assessed with the use of validated questionnaires. A subgroup of U.S. patients underwent photoprovocation testing. The primary efficacy end point was the number of hours of direct exposure to sunlight without pain.

RESULTS

In the U.S. study, the duration of pain-free time after 6 months was longer in the afamelanotide group (median, 69.4 hours, vs. 40.8 hours in the placebo group; P=0.04). In the European Union study, the duration of pain-free time after 9 months was also longer in the afamelanotide group than in the placebo group (median, 6.0 hours vs. 0.8 hours; P=0.005), and the number of phototoxic reactions was lower in the the afamelanotide group (77 vs. 146, P=0.04). In both trials, quality of life improved with afamelanotide therapy. Adverse events were mostly mild; serious adverse events were not thought to be related to the study drug.

CONCLUSIONS

Afamelanotide had an acceptable side-effect and adverse-event profile and was associated with an increased duration of sun exposure without pain and improved quality of life in patients with erythropoietic protoporphyria. (Funded by Clinuvel Pharmaceuticals and others; ClinicalTrials.gov numbers, NCT01605136 and NCT00979745.).

Investigation of safety, tolerability, pharmacokinetics, and pharmacodynamics of single and multiple doses of a long-acting α-MSH analog in healthy overweight and obese subjects

MC4-NN2-0453 is a novel, long-acting, selective, melanocortin-4-receptor agonist developed for treatment of obesity. This first-human-dose, randomized, double-blind, placebo-controlled trial investigated the safety, tolerability, pharmacokinetics, and pharmacodynamics of single and multiple doses of MC4-NN2-0453 in overweight to obese but otherwise healthy subjects. The trial included a single-dose part of ascending subcutaneous 0.03-1.50 mg/kg doses in overweight to obese but otherwise healthy men, and a multiple-dose part of ascending subcutaneous 0.75-3.0 mg/day doses in obese but otherwise healthy men/women. The single-dose part included 7 cohorts of 8 subjects, randomized 6:2 to active drug/placebo; the multiple-dose part included 4 cohorts of 20 subjects, randomized 16:4 to active drug/placebo. MC4-NN2-0453 was well tolerated and raised no safety concerns except for nonserious skin-related adverse events, this along with lack of weight loss effect led to premature termination of the trial. Headache, sexual-arousal disturbance, and penile erection were also reported. Single-dose pharmacokinetics showed dose-linearity and dose-proportionality. Maximum plasma concentration was observed after 50-100 hours, which then declined with a of approximately 250 hours. Plasma concentration reached steady state after 4 weeks for 0.75 and 1.5 mg/day multiple-dose cohorts, and the was similar to single dose. There were no significant pharmacodynamic effects, including effect on body weight.

Atypical melanocytic naevi following melanotan injection

Melanotan is a synthetic analogue of alpha melanocyte stimulating hormone (a-MSH) that stimulates melanogenesis. It is sold on the internet and tanning salons as a quick 'tanning jab'. We report a patient who developed multiple new onset atypical naevi within one week of receiving two Melanotan injections. This case highlights the potential risk of Melanotan in stimulating dysplastic naevi or possibly malignant melanoma.

[Melanotan-induced lentigines and nevi]

A 25-year-old man had self-injected more than 150 doses of melanotan to increase his skin pigmentation, which had increased significantly. At the same time, his nevi had become darker and new nevi and lentigines developed; they also occurred on his genitals causing his referral. Two nevi were excised, but showed no signs of malignant transformation.

Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization

The melanocortins (MCs) are a family of multifunctional peptidergic hormones. Several superpotent, prolonged acting, enzymatically resistant, MC analogs have been designed and synthesized to help clarify the nature and role of MCs and their receptors (MCRs) in physiological functions. Two of these analogs, a linear peptide, melanotan I, and a cyclic truncated peptide, melanotan II (MTI and MTII, respectively) have been patented and tested clinically for studies on tanning of the skin (MTI) and for diagnosis and treatment of male erectile dysfunction (MTII). A new MTII analog, PT-141 (Palatin Technologies) has initial phase I/II trials and is scheduled to enter pivotal stage III clinical trials leading to commercialization. MTI may provide a therapeutic tan with the potential to lower the risk of skin cancer. PT-141 may improve sexual functionality in both males and females.

Assessment of the aversive consequences of acute and chronic administration of the melanocortin agonist, MTII

BACKGROUND

The synthetic melanocortin (MC) agonist, melanotan-II (MTII), reduces food intake and body weight for hours to days after administration. One early report on the effect of MTII suggested that part of its anorexic action may be mediated by aversive consequences. In that experiment, MTII was found to support a mild conditioned taste aversion (CTA).

OBJECTIVE

The present experiments replicate and extend those findings in two additional CTA paradigms to further characterize the aversive effects of MTII in rats.

METHODS

Experiment 1 simultaneously assessed the ability of MTII to support CTA and reduce food intake, using a small oral infusion of a novel taste as the conditioned stimulus. Experiment 2 assessed the aversive consequences of chronic MTII administration. To accomplish this, we paired implantation of lithium chloride (LiCl)-, MTII- or saline-containing osmotic minipumps with a constantly available novel flavor. After 7 days, rats received a choice test between the minipump-paired flavor and a previously available neutral flavor.

RESULTS

Rats with saline minipumps exhibited no preference for either flavor. By contrast, rats in both the LiCl and MTII minipump groups significantly preferred the neutral flavor, indicating the development of a CTA. Additionally, CTA produced by administration of MTII was found to be more resistant to extinction than that produced by LiCl.

CONCLUSIONS

The reduction in food intake caused by MTII is accompanied by aversive consequences regardless of route of administration. These results present difficulties for the development of MCs-based therapies for obesity.

Central melanocortin receptors regulate insulin action

Energy balance and insulin action are tightly coregulated. Leptin regulates energy intake and expenditure partly by modulation of the melanocortin pathway in the hypothalamus. Here we demonstrate potent effects of the melanocortin pathway on insulin action and body distribution of adiposity. Conscious rats received week-long infusions of either a melanocortin receptor agonist, alpha-melanocyte-stimulating hormone (alpha-MSH), or antagonist, SHU9119, in the third cerebral ventricle while food intake was maintained constant in each group. alpha-MSH decreased intra-abdominal fat and markedly enhanced the actions of insulin on both glucose uptake and production, while SHU9119 exerted opposite effects. Our findings elucidate a neuroendocrine network that is likely to play a central role in the coupling of energy intake and insulin action.

Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II

We review our experience with Melanotan II, a non-selective melanocortin receptor agonist, in human subjects with erectile dysfunction (ED). Melanotan II was administered to 20 men with psychogenic and organic ED using a double-blind placebo-controlled crossover design. Penile rigidity was monitored for 6 h using RigiScan. Level of sexual desire and side effects were reported with a questionnaire. In the absence of sexual stimulation, Melanotan II led to penile erection in 17 of 20 men. Subjects experienced a mean of 41 min Rigiscan tip rigidity>80%. Increased sexual desire was reported after 13/19 (68%) doses of Melanotan II vs 4/21 (19%) of placebo (P<0.01). Nausea and yawning were frequently reported side effects due to Melanotan II; at a dose of 0.025 mg/kg, 12.9% of subjects had severe nausea. We conclude that Melanotan II is a potent initiator of penile erection in men with erectile dysfunction. Our findings warrant further investigation of melanocortin agonists and antagonists on penile erection. International Journal of Impotence Research (2000) 12, Suppl 4, S74-S79.

Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study

A pilot phase I study was conducted with a cyclic heptapeptide analog of alpha-melanocyte stimulating hormone (alpha-MSH). The lactam-bridged molecule, called Melanotan-II (MT-II), has the structure Ac-Nle4-Asp5-His6-D-Phe7-Arg8-Trp9-Lys10 alpha-MSH4-10-NH2 (MT-II) and has superpotent melanotropic activity in vitro. A single-blind, alternating day (saline or MT-II), placebo-controlled trial was conducted in 3 normal male volunteers at the starting dose of 0.01 mg/kg of MT-II. Subcutaneous injections of MT-II or saline were given daily (Monday-Friday) for 2 consecutive weeks. Two subjects were escalated by 0.005 mg/kg increments to 0.03 mg/kg and one to 0.025 mg/kg. The 0.03 mg/kg dose produced Grade II somnolence and fatigue in one of two subjects (WHO standards). Mild nausea, not requiring antiemetic treatment, was reported at most MT-II dose levels. A stretching and yawning complex appeared to correlate with the onset of spontaneous, penile erections which were intermittently experienced for 1-5 hours after MT-II dosing, depending on the MT-II dose. Two subjects had increased pigmentation in the face, upper body and buttock, as measured by quantitative reflectance and by visual perception 1 week after MT-II dosing ended. These results demonstrate that MT-II has tanning activity in humans given only 5 low doses every other day by subcutaneous injection. The recommended single MT-II dose for future Phase I studies is 0.025 mg/kg/day.