Aprepitant: a novel neurokinin-1 receptor/substance P antagonist as antipruritic therapy in cutaneous T-cell lymphoma

An update on mechanisms of pruritus and their potential treatment in primary cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas (CTCL), which include mycosis fungoides (MF) and Sézary syndrome (SS), are a group of lymphoproliferative disorders characterized by clonal accumulation of neoplastic T-lymphocytes in the skin. Severe pruritus, one of the most common and distressing symptoms in primary CTCL, can significantly impair emotional well-being, physical functioning, and interpersonal relationships, thus greatly reducing quality of life. Unfortunately, effectively managing pruritus remains challenging in CTCL patients as the underlying mechanisms are, as of yet, not fully understood. Previous studies investigating the mechanisms of itch in CTCL have identified several mediators and their corresponding antagonists used for treatment. However, a comprehensive overview of the mediators and receptors contributing to pruritus in primary CTCL is lacking in the current literature. Here, we summarize and review the mediators and receptors that may contribute to pruritus in primary CTCL to explore the mechanisms of CTCL pruritus and identify effective therapeutic targets using the PubMed and Web of Science databases. Studies were included if they described itch mediators and receptors in MF and SS. Overall, the available data suggest that proteases (mainly tryptase), and neuropeptides (particularly Substance P) may be of greatest interest. At the receptor level, cytokine receptors, MRGPRs, and TRP channels are most likely important. Future drug development efforts should concentrate on targeting these mediators and receptors for the treatment of CTCL pruritus.

Comparison of aprepitant versus desloratadine for EGFR-TKI-induced pruritus: A randomized phase 2 clinical trial

BACKGROUND

Pruritus is one of the most common and challenging side effects of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) and has impaired patients' quality of life and treatment compliance. Our study evaluated the efficacy and safety of aprepitant in managing EGFR-TKIs-related pruritus.

METHODS

This randomized, double-blind, placebo-controlled study was conducted between December 2016 and August 2020 in China. Patients were eligible if they were 18 years or older and had histologically confirmed locally advanced or metastatic non-small cell lung cancer (NSCLC) with first onset of moderate to severe pruritus during EGFR-TKI treatment.

RESULTS

A total of 130 eligible patients were randomly assigned to aprepitant (n = 65) or desloratadine (n = 65) groups. The median (interquartile range [Q1, Q3]) age was 63 (54, 70) years, and 79 (60.8%) were women. Mean visual analog scale scores at baseline were 6.35 (95% confidence interval [CI], 5.89-6.82) in the aprepitant group and 5.94 (95% CI, 5.56-6.32) in the desloratadine group. After 1 week of treatment, 33 (53.2%) patients responded to aprepitant, which was significantly higher than that of 14 (23.7%) patients responded to desloratadine (p = .001). Moreover, patients in the aprepitant group had a significantly shorter response time than patients in the desloratadine group (mean [days], 13.39 [95% CI, 11.08-15.70] vs. 16.67 [95% CI, 14.19-19.13], p = .04). The most frequent drug-related adverse events in aprepitant group and desloratadine were constipation and dry mouth, and all adverse events were grade 1-2.

CONCLUSIONS

To the authors' knowledge, this is the first study to prospectively present that aprepitant elicited a better and faster response and mild toxicity for managing EGFR-TKI induced pruritus than desloratadine.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02646020.

Pruritus: A Sensory Symptom Generated in Cutaneous Immuno-Neuronal Crosstalk

Pruritus or itch generated in the skin is one of the most widespread symptoms associated with various dermatological and systemic (immunological) conditions. Although many details about the molecular mechanisms of the development of both acute and chronic itch were uncovered in the last 2 decades, our understanding is still incomplete and the clinical management of pruritic conditions is one of the biggest challenges in daily dermatological practice. Recent research revealed molecular interactions between pruriceptive sensory neurons and surrounding cutaneous cell types including keratinocytes, as well as resident and transient cells of innate and adaptive immunity. Especially in inflammatory conditions, these cutaneous cells can produce various mediators, which can contribute to the excitation of pruriceptive sensory fibers resulting in itch sensation. There also exists significant communication in the opposite direction: sensory neurons can release mediators that maintain an inflamed, pruritic tissue-environment. In this review, we summarize the current knowledge about the sensory transduction of pruritus detailing the local intercellular interactions that generate itch. We especially emphasize the role of various pruritic mediators in the bidirectional crosstalk between cutaneous non-neuronal cells and sensory fibers. We also list various dermatoses and immunological conditions associated with itch, and discuss the potential immune-neuronal interactions promoting the development of pruritus in the particular diseases. These data may unveil putative new targets for antipruritic pharmacological interventions.

Helicobacter suis Infection in Mouse Induced not Only Gastric, but Hepatic and Pulmonary MALT Lymphoma: Relation to Substance P

BACKGROUND

The hepatic and pulmonary MALT lymphoma (mucosa-associated lymphoid tissue lymphoma) is clinically occasionally observed but its pathogenesis is unknown and thought to be important to establish the treatment strategy.

OBJECTIVES

The present study was designed to clarify the characteristics of these lymphomas and the effect of the Helicobacter eradication regimen and substance P antagonist.

METHODS

After the long term infection of Helicobacter suis to the C57BL/6 mice stomach, the whole organ was surveyed pathologically. Histochemical characteristics of the lesion and the localization of bacteria were observed. In addition, the effect of the administration of antibiotics and a proton pump inhibitor or the substance P antagonist was investigated.

RESULTS

We have detected the hepatic and pulmonary MALT lymphoma after the long term infection. In situ hybridization study revealed the positive reaction of Helicobacter suis in the hepatic and pulmonary MALT lymphoma. After the administration of antibiotics and a proton pump inhibitor, the bacterial number has significantly decreased and the tumor size in the fundus, liver and lung markedly reduced. Substance P immunoreactivity was clearly shown in the lymphoma cells in the liver and lung, and the spantide II administration induced the marked decrease in the size of tumors.

CONCLUSION

By our experiments using the long term infection of Helicobacter suis to the C57BL/6 mice, we have detected the liver and pulmonary MALT lymphoma. In situ hybridization study suggested the direct interaction of this bacterium to the etiology of these lesions. Substance P within the lymphoma cells was suggested to work on the maintenance of the extragastric MALT lymphoma.

Neurokinin-1 antagonist orvepitant for EGFRI-induced pruritus in patients with cancer: a randomised, placebo-controlled phase II trial

OBJECTIVE

To evaluate the efficacy of orvepitant (10 or 30 mg given once daily, orally for 4 weeks), a neurokinin-1 receptor antagonist, compared with placebo in reducing the intensity of epidermal growth factor receptor inhibitor (EGFRI)-induced intense pruritus.

DESIGN

Randomised, double-blind, placebo-controlled clinical trial.

SETTING

15 hospitals in Italy and five hospitals in the UK.

PARTICIPANTS

44 patients aged ≥18 years receiving an EGFRI for a histologically confirmed malignant solid tumour and experiencing moderate or intense pruritus after EGFRI treatment.

INTERVENTION

30 or 10 mg orvepitant or placebo tablets once daily for 4 weeks (randomised 1:1:1).

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary endpoint was change from baseline in mean patient-recorded numerical rating scale (NRS) score (over the last three recordings) at week 4. Secondary outcome measures were NRS score, verbal rating scale score, Skindex-16 and Leeds Sleep Evaluation Questionnaire at each study visit (baseline, weeks 1, 4, 8); rescue medication use; EGFRI dose reduction; and study withdrawal because of intense uncontrolled pruritus.

RESULTS

The trial was terminated early because of recruitment challenges; only 44 of the planned 90 patients were randomised. All patients were analysed for efficacy and safety. Mean NRS score change from baseline to week 4 was -2.78 (SD: 2.64) points in the 30 mg group, -3.04 (SD: 3.06) points in the 10 mg group and -3.21 (SD: 1.77) points in the placebo group; the difference between orvepitant and placebo was not statistically significant. No safety signal was detected. Adverse events related to orvepitant (asthenia, dizziness, dry mouth, hyperhidrosis) were all of mild or moderate severity.

CONCLUSIONS

Orvepitant was safe and well tolerated. No difference in NRS score between the orvepitant and placebo groups was observed at the week 4 primary endpoint. A number of explanations for this outcome are possible.

TRIAL REGISTRATION NUMBER

EudraCT2013-002763-25.

NK-1 Receptor Antagonists and Pruritus: Review of Current Literature

The discovery of the first neurokinin 1 (NK-1) receptor antagonist was a turning point in the prevention of chemotherapy-induced nausea and vomiting. The NK-1 antagonists are a novel class of drugs that possess antidepressant, anxiolytic, and antiemetic properties. Recently, clinicians have also described an anti-itch activity of NK-1 antagonists. We present herein results from currently available data on use of NK-1R antagonists in dermatology. For this purpose, a systemic electronic literature search of the PubMed and CINAHL databases, Cochrane Library, and clinicaltrials.gov website was performed. Based on currently available data, it can be concluded that NK-1 inhibitors show significant antipruritic potential for treatment of chronic pruritus in different dermatological conditions, but further studies are needed to establish the best indications and dosage of these drugs.

Emerging Treatments and Novel Pathways in Pruritus

Itch treatment is a major challenge in the dermatologist’s practice. We encounter patients suffering from pruritus on a regular basis, and often lack diverse treatment options to adequately respond to the patients’ needs. In the last 20 years, novel pathways have been investigated that were beyond the scope of histamine. Although most did not result in a molecule available on the Canadian market, it is interesting and important as health care providers to stay up to date with new neuronal pathways involved in itch transmission and potential new therapeutic options. In this review, we will discuss pathways targeted in new topical treatments such as antagonist of proteinase-activated receptor-2, the endocannabinoid system, neurotrophins and tropomyosin-related kinase A receptor, the transient receptor potential-vanilloid or transient receptor potential-melastatine ion channels. New systemic therapies are now focusing on antagonizing the neurokinin receptor, modulating the opioidergic system, or targeting itch cytokines such as interleukin-31.

Need for Flexible Adjustment of the Treatment Schedule for Aprepitant Administration against Erlotinib-Induced Refractory Pruritus and Skin Rush

Common dermatological side-effects associated with erlotinib, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), include pruritus and skin rash, which are mediated by substance P, leading to the occasional discontinuation of cancer treatment. Aprepitant is an antagonist of neurokinin-1 receptor, through which substance P activates the pruritogens. Thus, aprepitant is expected to offer a promising option for the treatment of erlotinib-induced pruritus. However, the appropriate treatment schedule for aprepitant administration is under consideration. Here, we discuss the need for flexible adjustment of the treatment schedule for aprepitant administration against erlotinib-induced refractory pruritus and skin rush. A 71-year-old female smoker presented with stage IV EGFR-mutated lung adenocarcinoma. She was started on erlotinib at 150 mg/day. However, by 28 days, severe pruritus and acneiform skin rush resistant to standard therapies occurred, resulting in the interruption of erlotinib therapy. After recovery, she was restarted on erlotinib at 100 mg/day. However, severe pruritus and skin rush developed again within 2 weeks. Then, we started the first 3-day dose of aprepitant (125 mg on day 1, 80 mg on day 3, and 80 mg on day 5) based on the results of the previous prospective study, which showed the success rate of 100% with at least the second dose of aprepitant. However, the pruritus and skin rush exacerbated again within 4 weeks. Therefore, we started the second 3-day dose of aprepitant, but in vain. At this point, as the patient-centered medicine, bi-weekly schedule of the 3-day dose of aprepitant was considered and, then, adopted. As the results, the pruritus and skin rush remained well-controlled throughout the subsequent treatment with erlotinib.

The Neurokinins: Peptidomimetic Ligand Design and Therapeutic Applications

The neurokinins are indisputably essential neurotransmitters in numerous pathoand physiological events. Being widely distributed in the Central Nervous System (CNS) and peripheral tissues, their discovery rapidly promoted them to drugs targets. As a necessity for molecular tools to understand the biological role of this class, endogenous peptides and their receptors prompted the scientific community to design ligands displaying either agonist and antagonist activity at the three main neurokinin receptors, called NK1, NK2 and NK3. Several strategies were implemented for this purpose. With a preference to small non-peptidic ligands, many research groups invested efforts in synthesizing and evaluating a wide range of scaffolds, but only the NK1 antagonist Aprepitant (EMENDT) and its prodrug Fosaprepitant (IVEMENDT) have been approved by the Food Drug Administration (FDA) for the treatment of Chemotherapy-Induced and Post-Operative Nausea and Vomiting (CINV and PONV, respectively). While non-peptidic drugs showed limitations, especially in side effect control, peptidic and pseudopeptidic compounds progressively regained attention. Various strategies were implemented to modulate affinity, selectivity and activity of the newly designed ligands. Replacement of canonical amino acids, incorporation of conformational constraints, and fusion with non-peptidic moieties gave rise to families of ligands displaying individual or dual NK1, NK2 and NK3 antagonism, that ultimately were combined with non-neurokinin ligands (such as opioids) to target enhanced biological impact.

Aprepitant for the Treatment of Chronic Refractory Pruritus

Chronic pruritus is a difficult condition to treat and is associated with several comorbidities, including insomnia, depression, and decreased quality of life. Treatment for chronic itch includes corticosteroids, antihistamines, and systemic therapies such as naltrexone, gabapentin, UV light therapy, and immunomodulatory treatments, including azathioprine, methotrexate, and cellcept. However, some patients still remain refractory to conventional therapy. Aprepitant is a neurokinin-1 receptor antagonist approved for the prevention of chemotherapy-induced and postoperative nausea and vomiting (CINV, PONV). Recently, aprepitant has demonstrated effectiveness in several case series and open label trials in relieving pruritus for patients refractory to other treatments. Patients with pruritus associated with Sézary syndrome, mycosis fungoides, lung adenocarcinoma, breast carcinoma, sarcomas, metastatic solid tumors, chronic kidney disease, hyperuricemia, iron deficiency, brachioradial pruritus, and Hodgkin's lymphoma have experienced considerable symptom relief with short-term use of aprepitant (up to two weeks). Due to differences in reporting and evaluation of drug effects, the mechanism of aprepitant's role is difficult to understand based on the current literature. Herein, we evaluate aprepitant's antipruritic effects and discuss its mechanism of action and adverse effects. We propose that aprepitant is an alternative for patients suffering from pruritus who do not obtain enough symptom relief from conventional therapy.

Aprepitant for refractory nivolumab-induced pruritus

Although substantial progress has been made in the treatment of non-small-cell lung cancer (NSCLC) patients with immune checkpoint inhibitors (ICIs), severe immune-related adverse events (irAEs) sometimes occur. Here, we report a case of severe refractory pruritus after Stevens-Johnson syndrome (SJS) in a patient with NSCLC treated with nivolumab. The patient was a 76-year-old Japanese woman with advanced NSCLC treated with nivolumab. After the second dose, she experienced severe rash with mucous involvement. We diagnosed SJS and started 50mg of oral prednisolone (1mg/kg). The rash completely resolved after prednisolone was started, but we could not manage the severe pruritus with emollients, antihistamines, and steroids. Finally, we administered aprepitant, an oral neurokinin-1 receptor antagonist, for her refractory pruritus. Her symptoms improved within 5days. Severe refractory pruritus can arise from ICIs, and aprepitant may be a useful treatment.

Aprepitant for refractory cutaneous T-cell lymphoma-associated pruritus: 4 cases and a review of the literature

Background

Aprepitant is an FDA-approved medication for chemotherapy-induced nausea and vomiting. It blocks substance P binding to neurokinin-1; substance P has been implicated in itch pathways both as a local and global mediator.

Case presentations

We report a series of four patients, diagnosed with cutaneous T-cell lymphoma, who experienced full body pruritus recalcitrant to standard therapies. All patients experienced rapid symptom improvement (within days) following aprepitant treatment.

Conclusion

Aprepitant has been shown in small studies to be efficacious for treating chronic and malignancy-associated pruritus. Prior studies have shown no change in clinical efficacy of chemotherapeutics with concurrent aprepitant administration. These cases further demonstrate that aprepitant can be considered as a therapeutic option in malignancy-associated pruritus and further support the need for larger clinical trials.

Treatment of pruritus in early-stage hypopigmented mycosis fungoides with aprepitant

Pruritus is a symptom that significantly affects the patient's quality of life in cutaneous T cell lymphoma (CTCL). The most effective treatments are those that address the condition itself; however, it is often not possible to control this symptom. Lymphoma-related pruritus normally becomes more severe as CTCL progresses, constituting an important factor for quality of life in these patients. Substance P is a neuromodulator which appears to play a key role in pruritus. Aprepitant is a neurokinin-1 receptor antagonist affecting the substance P receptor. So far, several cases have been documented with an antipruritic response to the drug aprepitant in advanced-stage mycosis fungoides (MF). In this paper, we describe an excellent response to aprepitant in a female patient with severe pruritus secondary to hypopigmented stage I MF. We would also like to stress the absence of nausea and vomiting of this combined therapy of interferon and aprepitant. Aprepitant could improve tolerance to interferon.