New quinoline derivatives 6, 7 and 19, pyrimidoquinoline derivatives 8-16 and triazolopyrimidoquinoline derivatives 17 and 18 bearing a bromo-substituent were synthesized starting from 3-(4-Bromophenylamino)-5,5-dimethylcyclohex-2-enone 3. All the newly synthesized compounds were evaluated for their in vitro anticancer activity against human breast cancer cell line (MCF7). Compounds 9, 11, 17 and 18 showed IC(50) values (36.4, 39.7, 39.02 and 36.4 μM, respectively) comparable to that of the reference drug doxorubicin (IC(50) = 32.02 μM). On the other hand, compound 6, 14 and 19 exhibited better activity than doxorubicin with IC(50) values of 8.5, 23.5 and 23.7 μM. Additionally, the most potent compounds 6, 14 and 19 were evaluated for their ability to enhance the cell killing effect of γ-radiation.