New Delhi, August 19, 2026

Indian scientists have developed a promising experimental cancer drug designed to work more selectively on tumour cells, potentially addressing one of the major limitations of conventional chemotherapy—the damage it can cause to healthy tissues. The candidate, RK-251, has been developed through collaborative research led by Dr. Asis Bala of the Institute of Advanced Study in Science and Technology (IASST) and Dr. K.P. Bhabak of the Indian Institute of Technology-Guwahati.

Unlike traditional chemotherapy, which can affect both cancerous and healthy cells, RK-251 is designed to remain largely inactive in normal tissues and become activated under conditions commonly associated with cancer cells. Tumour cells often have elevated levels of reactive oxygen species (ROS), and the researchers have used this characteristic as a trigger. Once RK-251 enters a cancer cell with high ROS levels, the drug is activated and releases an anticancer compound called NBDHEX. This compound targets proteins that help several cancer cells survive and develop resistance to treatment, allowing the drug to act primarily within tumour cells.

During preclinical experiments, RK-251 showed strong activity against triple-negative breast cancer cells, an aggressive form of breast cancer, while producing considerably lower effects on healthy cells. Researchers also tested the candidate using zebrafish embryos (Danio rerio). The behavioural assessment did not reveal obvious signs of toxicity, while the drug showed the expected fluorescence when exposed to reactive oxygen species. This fluorescence response also provided evidence supporting the proposed mechanism, indicating that the drug can become activated in an ROS-rich environment.

The findings indicate that RK-251 could serve as a potential platform for developing more targeted cancer therapies that selectively attack tumour cells while limiting harm to healthy tissues. However, the drug is still in the preclinical stage, and further research will be necessary to establish its safety, effectiveness and suitability before any testing in human clinical trials can be considered. The research has been published in the Journal of Medicinal Chemistry, an American Chemical Society (ACS) publication.