Advances in developing tris(8-quinolinolato)gallium(III) as an anticancer drug: critical appraisal and prospects

Gallium-based anticancer chemotherapeutics are appreciably progressing in clinical studies. A steady interest of drug developers and clinicians in gallium compounds is due to a proven ability of gallium cations to inhibit tumour growth, on the one hand, and enhanced bioavailability and moderate toxicity provided by the conversion of gallium into chelate complexes, on the other. One of the complexes suitable for a more convenient oral administration is tris(8-quinolinolato)gallium(III) (KP46). Nominated from a range of gallium complexes for the clinical stage of development, KP46 has finished phase I trials with the outcome of promising tolerability and evidence of clinical activity in renal cell carcinoma. Therefore, there is obviously a need to codify and critically evaluate the continuing advances in the emergence of KP46 as a lead-drug candidate. Additionally, many questions remain unanswered regarding the relevant biological reactivity, modes of delivery and action and potential cell target(s) of KP46. The timely publication of the present review is also an attempt to shed light on these pertinent drug assets and to accelerate research activities towards further clinical development of KP46.