Cancer's prevalence across the globe positions it as a major contributor to mortality, with only some cardiovascular diseases exceeding its impact. Cancer's intricacies lie in the mechanisms that trigger tumor growth, its staging, diagnosis, prognosis, and the challenge of treatment. While surgery, chemotherapy, and radiotherapy are commonly used treatment modalities, they often fall short of achieving the desired therapeutic outcome leaving patients vulnerable to relapse. Therefore, research efforts towards discovering new, highly effective and minimally invasive cancer therapies are on the rise. Currently, one of the most interesting therapies is direct suicide gene therapy. It consists in introducing a gene responsible for producing a toxin that can internally destroy the cancerous cell. In the present work our purpose was to investigate the antitumor efficacy of ldrB gene under the control of different promoters (induced or tumor-specific promoter) in cervix (HeLa) and breast (MCF-7) cancer cells. Experiments were conducted in vitro in 2D and 3D culture model and in vivo using NOD SCID mice. Our results showed that ldrB gene expression under the control of tumor-specific promoter causes a drastic inhibition of HeLa and MCF-7 cells proliferation in vitro in both 2D and 3D models. Moreover, an important decrease on cell viability was observed by ATPlite analysis. Furthermore, ldrB gene induced a severe loss of proliferation in vivo without any side effects in our animal model. Given our findings, the combination of the gene and promoter holds promising potential as a viable option for future therapies in breast and cervical cancer.