# Galen Cancer Research API

> Programmatic access to a 280,000-entity cancer knowledge graph with causal inference, drug-target analysis, and clinical interpretation. 28 integrated biomedical databases including ChEMBL, cBioPortal, DepMap, STRING, and OncoKB.

## API Base URL
https://api.usegalen.com/api/v1

## Authentication
API key via `X-API-Key` header. Get a free key at https://api.usegalen.com/quickstart

## Documentation
- [Full API Reference](https://api.usegalen.com/llms-full.txt)
- [OpenAPI Specification](https://api.usegalen.com/openapi.json)
- [Quickstart Guide](https://api.usegalen.com/quickstart)
- [Interactive Documentation](https://api.usegalen.com/reference)

## Core Capabilities

### Knowledge Graph (Free tier)
- `GET /api/v1/entities/{entity_id}` — Get entity profile (genes, drugs, diseases, pathways)
- `GET /api/v1/entities/search?q={query}` — Search entities by name
- `GET /api/v1/entities/{entity_id}/relationships` — Get entity relationships
- `POST /api/v1/entities/subgraph` — Extract a subgraph around entities
- `GET /api/v1/entities/{entity_id}/pch` — Get Pearl Causal Hierarchy annotations
- `POST /api/v1/entities/paths` — Find paths between entities

### Database Queries (Researcher tier, $49/mo)
- `GET /api/v1/chembl/compound/{name}` — Drug bioactivity data (Free tier)
- `GET /api/v1/depmap/gene/{gene}` — CRISPR gene essentiality
- `GET /api/v1/gdsc/drug/{drug}` — Drug sensitivity profiles
- `GET /api/v1/cbioportal/gene/{gene}` — Somatic mutation frequencies
- `GET /api/v1/gtex/gene/{gene}` — Tissue gene expression
- `GET /api/v1/string/protein/{protein}` — Protein-protein interactions
- `GET /api/v1/oncokb/gene/{gene}` — Clinical annotations
- `GET /api/v1/drugcomb/drug/{drug}` — Drug combination synergy

### Causal Inference (Researcher/Pro tier)
- `POST /api/v1/causal/intervention` — Simulate biological interventions (Researcher)
- `POST /api/v1/causal/explain` — Explain causal relationships (Researcher)
- `POST /api/v1/causal/do-calculus` — Run do-calculus queries (Pro, $199/mo)
- `POST /api/v1/causal/counterfactual` — Counterfactual reasoning (Pro)
- `GET /api/v1/causal/vulnerabilities/{entity}` — Find causal vulnerabilities (Researcher)
- `POST /api/v1/causal/dynamic-simulation` — Dynamic causal simulation (Pro)
- `GET /api/v1/causal/feedback-loops/{entity}` — Feedback loop detection (Researcher)

### Predictions (Researcher tier)
- `POST /api/v1/predictions/drug-response` — Predict drug response
- `POST /api/v1/predictions/essentiality` — Predict gene essentiality
- `POST /api/v1/predictions/mutation-effect` — Predict mutation effects
- `GET /api/v1/predictions/accuracy` — Prediction accuracy metrics

### Hypotheses (Researcher tier)
- `GET /api/v1/hypotheses/frontier` — Knowledge frontier (highest-value unknowns)
- `GET /api/v1/hypotheses/gaps/{entity}` — Knowledge gaps for an entity

### Patient Interpretation (Pro tier, $199/mo)
- `POST /api/v1/patient/profile` — Interpret multi-mutation profiles
- `POST /api/v1/patient/treatments` — Evidence-based treatment options
- `POST /api/v1/patient/resistance` — Treatment resistance mechanisms
- `POST /api/v1/patient/trials` — Clinical trial matching
- `POST /api/v1/patient/question` — Answer patient cancer questions

### System (Free tier)
- `GET /api/v1/health` — Health check
- `GET /api/v1/health/status` — Detailed system status
- `GET /api/v1/health/stats` — Knowledge graph statistics
- `GET /api/v1/health/data-sources` — Integrated data sources

## Example Request
```bash
curl -s "https://api.usegalen.com/api/v1/entities/EGFR" \
  -H "X-API-Key: your_api_key"
```

## Pricing
- **Explorer (Free)**: 100 req/day, KG queries + ChEMBL
- **Researcher ($49/mo)**: 5,000 req/day, all databases + causal + predictions
- **Pro ($199/mo)**: 50,000 req/day, full causal + patient interpretation
- **Enterprise (Custom)**: Unlimited, dedicated infrastructure + SLA

## Data Sources (28 integrated)
ChEMBL, cBioPortal, DepMap, GDSC, GTEx, STRING, OncoKB, DrugComb, COSMIC, ClinVar, PharmGKB, IntOGen, MSigDB, DrugBank, CTD, BioGRID, DisGeNET, TCGA, UniProt, Reactome, GO, PubMed, and more.

## Unique Capabilities (not available in free alternatives)
1. **Causal Inference**: Do-calculus and counterfactual queries via Structural Causal Models
2. **Pearl Causal Hierarchy**: Every relationship annotated as L1 (association), L2 (intervention), L3 (counterfactual)
3. **Patient Interpretation**: Multi-mutation profile analysis with treatment recommendations
4. **Cross-Evidence Validation**: Relationships validated across multiple independent data sources
5. **Knowledge Frontier**: Algorithmically identified highest-value unknowns in cancer biology