Figure shows mass spectrometry imaging of the PARP inhibitor niraparib in human ovarian tumor tissue. Warmer colors show regions of high drug accumulation or ‘hotspots’, while cooler colors show regions with lower drug levels. Credit: MRC Laboratory of Medical Sciences One of the biggest challenges in cancer care is that the same therapy can be highly effective for some patients yet fail entirely for others. A new study published in Nature Communications , led by Dr. Louise Fets at the MRC