Effect of PARP Inhibitors on Glomerular Filtration Rate

PARPi medications interact with transporters along the renal tubules involved in the secretion of creatinine and an increase in serum creatinine is often observed in patients treated with these agents; however, it is not known whether PARP inhibitors are associated with an actual change in the glomerular filtration rate, or if the observed elevations of serum creatinine are a result of a drug effect on creatinine secretion unrelated to changes in kidney function. The investigators therefore propose a prospective observational study to examine the incidence of elevation in serum creatinine from baseline levels in patients initiated on PARP inhibitors and compare the estimated glomerular filtration rate based on creatinine to that from alternative tests. The primary purposes of this study are to: * Assess the incidence of increase in serum creatinine in patients with a solid-organ cancer on treatment with a PARP inhibitor. * To compare the estimated glomerular filtration rate based on serum creatinine with that of alternative biomarkers to assess whether changes in serum creatinine reflect changes in kidney function or creatinine secretion. * To examine the persistence or resolution of creatinine increase and/or GFR decrease noted after discontinuation of PARPi