However, there are clearly many cells that lack this particular reversion, so it is interesting to speculate whether the bulk of the tumour cells would be expected to lack HR activity at this stage of the treatment – the frequency of the pathogenic BRCA2 and TP53 mutations was still high (81 and 88% respectively), suggesting that most cells would retain loss of function of these genes. The gene discussed is TP53; the disease is neoplasm.