Abstract: The present invention identifies new steroidal analogues of formestane synthesized through biotransformation with significant aromatase inhibitory activity, and thus can serve as possible safe, effective, and selective anti-cancer agent towards estrogen-responsive (ER+) breast cancer. Four new derivatives of anticancer drug formestane (1), 4?,5?,7?-trihydroxyandrostane-3,17-dione (2), 3?,7?-dihydroxyandrostane-4,17-dione (3), 3?,5?,7?-trihydroxyandrostane-4,17-dione (4), and 4,11?-dihydroxyandrosta-1,4-diene-3,17-dione (5) were synthesized through bio-catalyzed structural modifications by Cunninghamella. blakesleeana and Fusarium lini. The new derivatives showed varying degree of inhibition of aromatase enzyme. Metabolite 4 (IC50=0.386±0.072 ?M), showed a significant inhibitory potential, comparable to substrate 1 (IC50=0.335±0.011 ?M) and standard aromatase inhibitory anti-cancer drug exemestane (IC50=0.232±0.031 ?M). Metabolites 3 (IC50=1.37±0.029 ?M), and 2 (IC50=5.229±0.