Methotrexate

證據等級: L5

預測適應症: 10 個

Methotrexate: From Hematologic Malignancies to Pulmonary Blastoma

One-Sentence Summary

Methotrexate is a well-established antifolate antimetabolite with decades of clinical use across hematologic malignancies (including leukemia, lymphoma, and osteosarcoma) and autoimmune diseases (including rheumatoid arthritis and psoriasis). The TxGNN model predicts it may be effective for Pulmonary Blastoma, with no clinical trials and no publications currently supporting this specific direction — evidence level L5.

Quick Overview

Item	Content
Original Indication	Hematologic malignancies and autoimmune diseases (no India regulatory data on file)
Predicted New Indication	Pulmonary Blastoma
TxGNN Prediction Score	99.45%
Evidence Level	L5 (model prediction only, no actual studies)
India Market Status	Not Marketed
Number of Registrations	0
Recommended Decision	Hold

Why is This Prediction Reasonable?

Currently, detailed mechanism of action data is not available in this evidence pack. Based on known information, Methotrexate is a folate antagonist belonging to the antifolate antimetabolite class of cytotoxic agents. Its efficacy across hematologic malignancies — particularly acute lymphoblastic leukemia, non-Hodgkin’s lymphoma, and primary CNS lymphoma — has been firmly established over decades of clinical use. The drug functions by inhibiting dihydrofolate reductase (DHFR), thereby blocking the synthesis of thymidylate and purines that are essential for DNA replication in rapidly dividing cells. Evidence collected from related predictions in this report (primary pulmonary lymphoma, small cell lung carcinoma, Hodgkin’s lymphoma, rhabdomyosarcoma) consistently identifies the DHFR-inhibition pathway as the mechanistic anchor for MTX’s antitumor activity.

Pulmonary blastoma is a rare, aggressive embryonal tumor of the lung with a biphasic architecture combining primitive epithelial and mesenchymal components. The TxGNN model predicts that its rapidly proliferating embryonal cells may be sensitive to DHFR inhibition — the same logic that underlies MTX’s activity in other high-proliferation embryonal tumors such as rhabdomyosarcoma and Wilms’ tumor. The high proliferative index characteristic of embryonal-type malignancies is precisely the cellular state most vulnerable to antifolate-mediated thymidylate depletion.

However, this mechanistic bridge remains entirely theoretical for pulmonary blastoma specifically. There are no clinical trials, no published case reports, and no preclinical studies examining MTX activity in this rare tumor type. The TxGNN prediction score of 99.45% reflects graph neural network pattern recognition based on biological network proximity within the knowledge graph — not direct experimental evidence. Until preclinical data are generated, this remains a hypothesis-only candidate.

Clinical Trial Evidence

Currently no related clinical trials registered.

Literature Evidence

Currently no related literature available.

India Market Information

Methotrexate has no registered products in India according to this regulatory dataset (0 approved licenses, market status: Not Marketed). International approvals should be referenced for formulation and approved indication details.

Cytotoxicity

Methotrexate is a conventional cytotoxic antimetabolite used across multiple oncology indications. This section applies.

Item	Content
Cytotoxicity Classification	Conventional cytotoxic (Antifolate / Antimetabolite class)
Myelosuppression Risk	High — bone marrow suppression is a well-recognized dose-limiting toxicity; neutropenia, thrombocytopenia, and anemia are common, particularly with high-dose regimens
Emetogenicity Classification	Low to moderate
Monitoring Items	CBC with differential count, ALT/AST/bilirubin (hepatotoxicity risk), serum creatinine and creatinine clearance (nephrotoxicity risk), serum MTX concentration (mandatory for high-dose protocols), folate/leucovorin rescue status
Handling Protection	Must follow cytotoxic drug handling regulations; specialized preparation, administration, and disposal procedures required

Safety Considerations

Drug Interactions: A total of 784 drug-drug interactions have been identified for Methotrexate. Clinically significant interactions include:

Major interactions (require avoidance or close monitoring):

Rabeprazole — Proton pump inhibitors impair renal MTX clearance via OAT3 transporter inhibition, substantially raising MTX plasma exposure and toxicity risk
Amoxicillin — Beta-lactam antibiotics compete with MTX for renal tubular secretion, increasing MTX levels and risk of myelosuppression/mucositis
Acetylsalicylic acid (Aspirin) — NSAIDs and salicylates reduce MTX renal clearance and displace it from plasma protein binding, compounding toxicity; concurrent use should be avoided especially at higher MTX doses

Selected moderate interactions:

Amphotericin B / Amphotericin B (lipid complex) — Additive nephrotoxicity risk that can reduce MTX renal clearance
Mesalazine / Balsalazide — Aminosalicylates may inhibit hepatic MTX metabolism, increasing systemic exposure
Doxycycline / Tetracycline — Antibiotic interference with MTX absorption and enterohepatic recycling
Hydrocortisone / Dexamethasone / Betamethasone / Budesonide / Triamcinolone — Combined immunosuppression; corticosteroids may modulate MTX anti-inflammatory efficacy
Clarithromycin — Transporter-mediated pharmacokinetic interaction
Bupropion — Moderate interaction; CNS toxicity risk may be additive

Conclusion and Next Steps

Decision: Hold

Rationale: Although TxGNN assigns a high prediction score (99.45%) for Methotrexate in pulmonary blastoma based on graph-level biological network proximity, there is a complete absence of any supporting clinical, observational, or preclinical evidence for this specific indication. Pulmonary blastoma is an extremely rare malignancy with no established chemotherapy standard, and no data exist to confirm DHFR pathway dependency in this tumor subtype.

To proceed, the following is needed:

Preclinical studies: In vitro cytotoxicity assays and in vivo xenograft experiments in pulmonary blastoma models to establish MTX antitumor activity
Pathway validation: Confirm DHFR expression levels and folate pathway dependency in pulmonary blastoma tumor tissue or cell lines
Retrospective case mining: Systematic search for any historical case reports describing MTX use in pulmonary blastoma management
Safety data gap resolution: Obtain the official MTX package insert (IND/NDA-approved label) to document full warnings, contraindications, and special population guidance
MOA documentation: Retrieve complete DrugBank mechanism of action data to formally characterize the folate antagonism rationale for this indication
Rare disease expert input: Consultation with thoracic oncologists and pediatric oncologists specializing in rare lung malignancies before any clinical hypothesis is advanced

⚠️ This report is for research reference only and does not constitute medical advice. All drug repurposing candidates require clinical validation before application.

Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.