Researchers have uncovered critical safety concerns regarding a promising class of anticancer treatments currently in development. A collaborative study from King's College London and Jagannath University in Bangladesh has revealed that gold-based cisplatin mimics—touted for their potential to deliver chemotherapy with fewer side effects—may contain unknown dangerous compounds, challenging decades of established chemistry.
The research, published in Dalton Transactions, demonstrates that the synthesis process for gold(III) dithiocarbamate compounds does not yield the pure product that scientists have believed since 1964. Instead, it produces a mixture of isomers—molecules with identical elemental composition but different structural arrangements—which could pose significant safety risks.
Unexpected Discovery Challenges 60 Years of Chemistry
The research team found that when attempting to synthesize these gold-based compounds in conditions mimicking the human body, it was impossible to obtain a pure compound. In many cases, the primary component was a positively charged cisplatin mimic, contradicting previous studies that described these compounds as neutral.
"We were not expecting this result at all," said Dr. David Pugh, Lecturer in Inorganic Chemistry at King's College London and lead author of the study. "When we first started making these compounds, we trusted that the literature was accurate – but we now know that this is not the case."
This finding has profound implications, potentially invalidating nearly 100 scientific publications dating back to 1964 that have described the synthesis and properties of these compounds.
Potential Implications for Patient Safety
The discovery raises serious concerns about the safety profile of these compounds should they advance to clinical trials. The history of pharmaceutical development offers sobering precedents for the dangers of isomeric compounds. In the 1960s, the thalidomide tragedy occurred when one isomer of the morning sickness medication caused severe birth defects, leading to stricter pharmaceutical regulations worldwide.
"This means the toxicity of these compounds has not been rigorously tested, and that by using these drugs, we're potentially stepping into dangerous, unknown territory," Dr. Pugh explained. "This demands a serious re-think in how we use them before they potentially hit the market."
Promise of Improved Cancer Treatment
The gold-based cisplatin mimics had generated significant interest in the oncology community because they function similarly to cisplatin, a widely used platinum-based chemotherapy drug. However, the gold compounds were expected to cause fewer of the debilitating side effects typically associated with cancer treatment, such as extreme fatigue and hair loss.
These compounds are part of the gold(III) dithiocarbamate family of chemical compounds. While they are not currently in clinical use or trials, several research groups have been investigating their potential, and patents have been filed for their use as anticancer agents.
Path Forward Requires Rigorous Testing
In light of their findings, the research team is urging the scientific community to conduct further studies on these mixtures before any clinical development proceeds. The researchers emphasize that comprehensive toxicity testing must be performed on the actual mixture of compounds that would be administered to patients, rather than on the theoretical pure compound that previous literature had described.
The study serves as a reminder of the importance of rigorous chemical characterization in drug development and highlights how even long-established scientific "facts" may require reexamination with advanced analytical techniques.
The research was published in Dalton Transactions (2025; 54(19):7627-7640) under the title "A revised understanding of the speciation of gold(III) dithiocarbamate complexes in solution."
