| abstract |
The present invention provides a pharmaceutical composition having a steroid C 17,20 lyase inhibitory activity and useful as a preventive / therapeutic agent for tumors such as prostate disease and breast cancer. SOLUTION: Formula: (In the formula, A 1 represents an optionally substituted aromatic hydrocarbon group or an optionally substituted heterocyclic group, one of A 2 and A 3 is a hydrogen atom, a halogen atom, A C 1-4 aliphatic hydrocarbon group which may have a substituent or a carboxyl group which may be esterified, an aromatic carbon which the other of A 2 and A 3 may have a substituent A hydrogen group or an optionally substituted heterocyclic group is shown, but at least one of A 1 , A 2 and A 3 is an optionally substituted 3-pyridyl group). A steroid C 17,20 lyase inhibitor comprising the compound represented by the formula: [Selection figure] None |