Methoxsalen
| Evidence Level: L5 | Predicted Indications: 8 |
Table of Contents
- Methoxsalen
- Pharmacist Assessment Report
- Methoxsalen: From Cutaneous T-Cell Lymphoma to Localized Pagetoid Reticulosis
- One-Sentence Summary
- Quick Overview
- Why is This Prediction Reasonable?
- Clinical Trial Evidence
- Literature Evidence
- India Market Information
- Cytotoxicity
- Safety Considerations
- Conclusion and Next Steps
- Disclaimer
Methoxsalen: From Cutaneous T-Cell Lymphoma to Localized Pagetoid Reticulosis
One-Sentence Summary
Methoxsalen is a photosensitising agent (psoralen) used with UVA light (PUVA) and in extracorporeal photopheresis. It was originally used for cutaneous T-cell lymphoma and vitiligo. The TxGNN model predicts it may be effective for localized pagetoid reticulosis, an indolent epidermotropic variant of cutaneous T-cell lymphoma. Currently there are 0 clinical trials and 0 publications directly supporting this prediction, so the support is mechanistic and class-level inference only.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Primary cutaneous T-cell lymphoma (including non-Hodgkin type); vitiligo |
| Predicted New Indication | Localized pagetoid reticulosis |
| TxGNN Prediction Score | 0.9997 |
| Evidence Level | L5 |
| India Market Status | Listed in a compiled Indian medicine price dataset (at least 20) – CDSCO approval status is not included in this data |
| Number of Listed Products | at least 20 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available in the data compiled for this report. Based on known pharmacology, methoxsalen is activated by UVA light and forms DNA crosslinks, which induces apoptosis in malignant epidermal T cells. Its efficacy in cutaneous T-cell lymphoma is established, and it may be mechanistically applicable to localized pagetoid reticulosis.
Localized pagetoid reticulosis (Woringer-Kolopp disease) is an indolent, epidermotropic variant of primary cutaneous T-cell lymphoma. It therefore sits very close to the original indication, and photochemotherapy acts on the same skin-homing T-cell biology.
The very high TxGNN score mainly reflects this proximity to an existing indication. It is not independent clinical evidence, and this is closer to an overlap with the original indication than a true repurposing signal.
The other nine predictions are weaker. The second-ranked prediction, indolent primary cutaneous T-cell lymphoma, has a similar rationale and one indirect reference. The remaining eight are B-cell lymphomas (including MALT lymphomas, Burkitt lymphoma, tonsillar lymphoma and a follicular lymphoma susceptibility entry) and a benign vulvar lesion. They have no plausible mechanistic link and were all rated Hold at evidence level L5. UVA-activated methoxsalen cannot reach deep or visceral disease.
Clinical Trial Evidence
Currently no related clinical trials are registered for localized pagetoid reticulosis.
Literature Evidence
No literature was found for localized pagetoid reticulosis. For the related second-ranked prediction, indolent primary cutaneous T-cell lymphoma, one reference is available:
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 23074497 | 2006 | Review (health technology assessment) | Ontario Health Technology Assessment Series | Evidence-based analysis of the effectiveness, safety and cost-effectiveness of extracorporeal photopheresis in refractory erythrodermic CTCL and refractory chronic graft-versus-host disease. Indirect, secondary evidence. |
India Market Information
Twenty valid single-ingredient registrations exist. The data compiled for this report contains no approved indication text for any of them. The main authorizations are:
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| 138256 | Macsoralen Lotion | Bottle of 15 ml solution | Not available |
| 201942 | Salen Capsule | Strip of 10 capsules | Not available |
| 147728 | Misvic 10mg Tablet | Strip of 10 tablets | Not available |
| 139157 | Maxlen 10mg Tablet | Strip of 20 tablets | Not available |
| 133618 | Melanocyl Tablet | Strip of 40 tablets | Not available |
Cytotoxicity
| Item | Content |
|---|---|
| Cytotoxicity Classification | Photoactivated DNA-crosslinking agent (used with UVA). Not a conventional cytotoxic chemotherapy |
| Myelosuppression Risk | Please refer to the package insert warnings and precautions |
| Emetogenicity Classification | Please refer to the package insert warnings and precautions |
| Monitoring Items | Please refer to the package insert warnings and precautions |
| Handling Protection | Please refer to the package insert warnings and precautions |
Safety Considerations
- Contraindications (from the knowledge graph, not label text): The following disease associations are recorded.
- Photosensitivity: photosensitivity disease, photoparoxysmal response.
- Porphyrias: porphyria, variegate porphyria, porphyria cutanea tarda, erythropoietic protoporphyria and related porphyrin metabolism disorders.
- Skin cancers: melanoma, basal cell carcinoma, squamous cell carcinoma, skin carcinoma and other carcinomas.
- Other: xeroderma pigmentosum, albinism, systemic lupus erythematosus, liver disease, gallbladder disease, Waardenburg syndrome, piebaldism and Griscelli syndrome.
- Drug Interactions: 126 interactions were recorded. The 20 listed are all Moderate. They include tetracycline-class antibiotics (doxycycline, tetracycline, minocycline), sulfonylureas (glimepiride, glipizide, glyburide, chlorpropamide, tolbutamide, tolazamide, acetohexamide), levofloxacin, sulfasalazine, sulfamethizole, promethazine, alosetron, and NSAIDs (ibuprofen, flurbiprofen). Many of these probably relate to additive photosensitivity or other photosensitising effects.
Package insert warnings and contraindications could not be obtained. Please refer to the package insert for complete safety information.
Conclusion and Next Steps
Decision: Hold
Rationale: The top prediction, localized pagetoid reticulosis, is plausible, but it is essentially an extension of the approved cutaneous T-cell lymphoma indication. No trials or literature support it, and the high score reflects proximity to the existing indication rather than new evidence. Package insert safety data are missing, and the knowledge graph flags several relevant contraindications, including skin cancers and photosensitivity disorders. The B-cell lymphoma predictions have no plausible mechanism.
To proceed, the following is needed:
- Case series, registry data or guideline evidence for PUVA in localized pagetoid reticulosis
- Package insert warnings and contraindications from the Indian regulator or manufacturers, and approved indication text for the registered products
- Detailed mechanism of action data (MOA)
- Route and formulation compatibility assessment (oral, topical and extracorporeal use)
- A safety plan for photosensitivity, skin cancer risk and drug interactions
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.