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Phase 2 tests the chosen dose for response in a specific cancer, sometimes randomised and sometimes single-arm, and phase 3 is the large randomised, often blinded, comparison against the standard of care that regulators normally require for full approval. Phase 4 studies follow a marketed drug. Only around 5% of oncology drugs entering phase 1 reach approval, and around a third of phase 3 trials fail, which is a major driver of drug 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