Plasma Exchange and Daratumumab for Myeloma Cast Nephropathy

Multiple myeloma light chain cast nephropathy (LCCN) is often treated with plasma exchange (PLEX) or the anti-CD38 monoclonal antibody, daratumumab. However, rigorous studies supporting these therapies for LCCN are limited. Using data from 25 U.S.-based academic cancer centers, we conducted two target trials examining the association between early receipt of PLEX or early receipt of daratumumab and kidney recovery in patients with newly diagnosed LCCN. Kidney recovery was defined as being alive, not on kidney replacement therapy, and with an improvement of at least one stage of AKI severity, all assessed at 90 days. Secondary outcomes included kidney recovery at 60 and 180 days. Logistic regression with propensity score overlap weights was used to adjust for confounders. Of 549 eligible patients for the PLEX target trial, 158 (28.8%) received PLEX. There was no association between PLEX and kidney recovery at 90 days (OR 1.48, 95% CI: 0.96-2.30). However, in subgroup analyses, PLEX was associated with higher odds of kidney recovery at 90 days among patients with newly diagnosed multiple myeloma compared to those with relapsed disease, as well as higher odds of kidney recovery among those with Stage 3 versus Stage 1 or 2 AKI at the time of LCCN diagnosis. Of 474 patients eligible for the daratumumab target trial, 136 (28.7%) received daratumumab. Daratumumab was not associated with kidney recovery at 90 days (OR 1.46, 95% CI: 0.84-2.55). Thus, in this multicenter cohort study, neither PLEX nor daratumumab was associated with kidney recovery at 90 days.