Inhibition of Pol I Transcription a New Chance in the Fight Against Cancer

While new cancer treatments continue to improve patient outcomes, for some cancers there have been limited or no improvements for a long time. It is for these cases radically new approaches are required. Recent publications proposing ribosome biogenesis, in particular RNA polymerase I transcription, as a suitable target for cancer treatment has been gaining momentum. For example, we demonstrated that CX-5461, a specific RNA polymerase I transcription inhibitor, is effective in treating an aggressive subtype of acute myeloid leukemia, regardless of p53 status. Notably, CX-5461 reduces the leukemia initiating/stem cells, the cell population believed to be responsible for chemotherapy resistance and disease relapse in numerous cancers. Targeting ribosome biogenesis, once considered merely a “housekeeping process,” is showing promise in a continuously growing list of cancers including lymphoma, prostate, and now acute myeloid leukemia. Evidence suggests the therapeutic efficacy of RNA polymerase I therapy in preclinical models is mediated through a variety of mechanisms including nucleolar stress activation of p53, DNA damage-like activation of ataxia-telangiectasia mutated/ataxia-telangiectasia and Rad3 related, and cellular differentiation. Overall, the available data suggests the potential for targeting ribosome biogenesis to be effective in a broad spectrum of cancers. The outcomes of 2 phase 1/2 trials of CX-5461 in hematological malignancies and breast cancer are eagerly awaited.