SUrvey of renal Biopsy registry database and Anticancer dRUg therapy in Japan (SUBARU-J study)

Kidney complications associated with anticancer drug therapy have greatly increased recently. We aimed to investigate the real-world clinical outcomes of anticancer drug therapy-associated renal complications in Japan using the national kidney biopsy database, Japan Renal Biopsy Registry (J-RBR).

From 2018 to 2021, 449 cases from 49 facilities identified as 'drug-induced' histopathology in the J-RBR were screened, of which a total of 135 were confirmed as anticancer drug-related cases and included in the analysis. Overall survival rates were estimated using the Kaplan-Meier method and compared by logrank test. The Cox regression model was used to evaluate the association between variables and deaths.

The most common primary sites of malignancies were the lung (33.3%), followed by gastrointestinal (16.3%) and gynaecological (11.1%) cancers. Tubulointerstitial nephritis (TIN; 47.4%) and thrombotic microangiopathy (TMA; 35.6%) were the most frequent diagnoses. All immunoglobulin A nephropathy, minimal change disease and crescentic glomerulonephritis (CrGN) cases were immune checkpoint inhibitor related. All CrGN cases were anti-neutrophil cytoplasmic antibody negative. Antibiotics were most frequently used concomitantly with anticancer drugs in TMA cases among subgroups (TMA versus others: 62.5 versus 27.5%; P < .001). Among TMA cases, the serum lactate dehydrogenase level tended to be higher in cytotoxic agent-associated TMA (CTx-TMA) than in other TMAs, but was not significant between groups (415.5 versus 219.0 U/l; P = .06). Overall survival was worse in CTx-TMA than in other TMAs (P = .007). The Cox model demonstrated proton pump inhibitor (PPI) use (hazard ratio 2.49, P = .001) as a significant prognostic factor, as well as the presence of metastasis and serum albumin level.

Our registry analysis highlighted various presentations of biopsy-proven kidney complications associated with anticancer drug therapy. Clinicians should be aware of worse outcomes associated with CTx-TMA and the prognostic role of PPI use.