Responses to Topical Diphenylcyclopropenone as an Adjunct Treatment for In-Transit Melanoma: A Tertiary Referral Center Experience

An overview of cyclopropenone derivatives as promising bioactive molecules

Cyclopropenone is a valuable electrophilic reagent that can react with electrophilic reagents, nucleophilic reagents, free radicals, organic metals, etc. Furthermore, cyclopropenone derivatives have shown significant biological activity in various diseases, such as triple-negative breast cancer (TNBC), melanoma, and alopecia areata (AA). The cyclopropenone analogue diphenylcyclopropenone (DPCP) has been approved for the treatment of AA. Given the potential therapeutic benefits of cyclopropenone derivatives, this review aims to systematically summarize the structures, synthesis routes, and potential pharmacological functions of cyclopropenone analogues in the hope of offering novel insights for further rational design of more drugs based on the cyclopropenone skeleton for the treatment of human diseases.

Case report: Regression of in-transit metastases of cutaneous squamous cell carcinoma with combination pembrolizumab and topical diphencyprone

While typically low-risk, cutaneous squamous cell carcinoma (cSCC) can infrequently progress to metastatic disease with in-transit lesions, localized to the dermis or subcutaneous tissue between the primary tumor and draining regional lymph nodes. These lesions are associated with poor prognostic values, including decreased survival rates and increased risk of recurrence. We present the case of a 75-year-old male with cSCC and in-transit metastases on his scalp treated with the immune checkpoint inhibitor (ICI) pembrolizumab in conjunction with diphencyprone (DPCP), a topical hapten that induces a delayed-type hypersensitivity reaction in the skin. The patient was enrolled in a clinical trial (NCT05481658) that involved the twice-weekly application of DPCP 0.04% ointment to four of the in-transit metastases on his frontal scalp, concurrent with pembrolizumab 300 mg administered every three weeks. Following effective sensitization and a twelve-week treatment course, complete clearance of all lesions, DPCP-treated and non-DPCP treated, was achieved, with no adverse events. The immunologic profiles of the post-treatment biopsies were analyzed by TaqMan Low Density Array quantitative real-time polymerase chain reaction to measure immune marker gene expression. Relative to the non-DPCP-treated lesion, the DPCP-treated lesion demonstrated increased pro-inflammatory genetic markers and T-cell activation. This case represents the first reported instance of in-transit metastases of cSCC successfully treated with DPCP and an ICI. It highlights the potential safety and efficacy of DPCP with systemic immunotherapy for the management of in-transit metastases of cSCC in patients for whom surgery and radiation may be contraindicated.

Theoretical Appraisal of Cyclopropenone: Aggregation and Complexes with Water

Cyclopropenone (HCCOCH, "CPN") is an exotic quasi-aromatic cyclic carbene that abounds in the interstellar medium (ISM). Astronomical observations suggest that (i) stagnate CPN exhibits a tendency to polymerize and that (ii) interactions may occur between CPN and water that is also ubiquitous in the ISM. In this light, density functional theory investigations reveal cooperative hydrogen bonding, which leads to stable polymeric conformations of (CPN)_n, tracked up to n = 14. Stable agglomerations with water, however, constitute at best only two CPN and two water molecules, signifying that while CPN exhibits remarkable cooperativity for "cohesive" clustering via hydrogen bonding, this tendency is markedly diminished for "hetero"-interactions. Multifaceted data are employed to probe cogent molecular descriptors, such as structure and energetics of various conformers, vibrational spectroscopic response, molecular electrostatic potential (MESP), effective atomic charges: all these, in unison, describe the evolution of the characteristics upon cluster formation. Salient stretching frequency shifts, as well as charge redistribution gleaned from MESP morphology, have a direct bearing on variegated hydrogen bonding patterns: linear, nonlinear, as well as bifurcated. In particular, characteristic C-H, C═O stretching, and O-H vibrations in the water complexes reveal a "softening" (downshift) of frequencies. While small conformers have markedly distinct MESP variations, the differences become less pronounced with incremental clustering, an effect substantiated by corresponding emergent atomic charges.

Use of Contact Immunotherapy in the Treatment of Skin Diseases Other than Alopecia Areata

For decades, contact immunotherapy with dinitrochlorobenzene, diphencyprone, and squaric acid dibutylester has played an important role in both clinical practice and scientific research. It is listed as the first-line treatment for extensive alopecia areata and was more recently approved for melanoma treatment as an orphan drug in the USA. Moreover, owing to the relative low cost and safety, topical immunotherapy has also been used in many infectious, neoplastic, and inflammatory dermatological diseases. It is especially valuable in vulnerable groups, for cosmetic/pain sensitive areas, or for multiple lesions. In this review, we summarize the current evidence supporting the use of contact immunotherapy for treatment of skin diseases, from articles collected from PubMed database. Owing to space limitation and already numerous studies focusing on alopecia areata, we include only skin diseases other than alopecia areata. In addition to diseases that have been reported to be treated by contact immunotherapy, the hypothesized mechanism, prognosis prediction, efficacy, and safety of these topical agents are discussed.

Heterocycles from cyclopropenones

Great attention has been paid to cyclopropenones as they are present in many natural sources. Various synthesized cyclopropenone derivatives also show a wide range of biological activities. The cyclopropenone derivatives undergo a variety of reactions such as ring-opening reactions, isomerization reactions, C-C coupling reactions, C-H activation, cycloaddition reactions, thermal and photo-irradiation reactions, and acid-base-catalyzed reactions under the influence of various chemical reagents (electrophiles, nucleophiles, radicals, and organometallics) and external forces (heat and light). Many previous reviews have dealt with the chemistry and reactions of cyclopropenones. However and to the best of our knowledge, the utility of cyclopropenones in the synthesis of heterocycles has not been reported before. Therefore, it would be interesting to shed light on this new topic. The present review article provides, for the first time, a comprehensive compilation of synthetic methods for the synthesis of various heterocyclic ring systems, as a significant family in the field of organic chemistry.

The Landmark Series: Regional Therapy of Recurrent Cutaneous Melanoma

In-transit melanoma represents a distinct disease pattern in which melanoma recurs as dermal or subcutaneous nodules between the primary melanoma site and the draining regional lymph node basin. The disease pattern is often not amenable to complete surgical resection. Since the 1950s, regional therapies have been explored for the treatment of this disease entity, with the goal of maximizing delivery of the therapeutic agent to the tumor while minimizing systemic toxicity. We reviewed landmark studies describing and evaluating regional chemotherapy and intralesional therapies for patients with in-transit melanoma metastases.

Topical and intralesional therapies for in-transitmelanoma

This report surveys the role of topical and intralesional agents in the management of in-transit melanoma. The extent and progression of in-transit disease is highly variable and many patients can have a protracted period of locoregional control. These agents are useful in the management of patients who have progressed beyond local surgical excision in whom more aggressive therapies, such as isolated limb infusion or use of talimogene laherparepvec, are not appropriate or have failed. In general, these agents are modestly effective and associated with frequent but only minor toxicity. As the mechanism of action of many of these agents includes initiation of a local immune response, combinations with immune checkpoint inhibitors are currently being explored.

Immunomodulatory effects of topical diphencyprone for the treatment of acute urban cutaneous leishmaniasis

BACKGROUND AND OBJECTIVE

Efficacious and safe treatments are lacking for cutaneous leishmaniasis (CL). This study investigates the efficacy of adding diphencyprone immunotherapy to conventional meglumine antimoniate (MA) treatment for acute urban CL.

METHODS

This randomized controlled pilot study included 46 patients with acute CL. They were randomly allocated to receive either combination of diphencyprone immunotherapy with intralesional MA (intervention; N = 23) or intralesional MA alone (control; N = 23) weekly. The size and duration of lesions were measured at the baseline and after that at 4th, 8th, 12th, and 24th weeks. Data were analyzed in SPSS and p < .05 was considered significant.

RESULTS

The groups showed no significant difference in duration of lesions, but number of injections was significantly higher in the control group compared with the intervention group (p < .001). Size and induration of lesions was significantly reduced in both groups during the course of study (p < .001). The intervention group showed significantly lower induration of lesions in 4th, 8th, and 12th week compared with controls (p < .05).

CONCLUSION

Combination of diphencyprone with MA resulted in earlier resolution of acute CL lesions with a relatively acceptable rate of adverse effects, compared with intralesional MA alone.