Clinical and Renal Outcomes in Multiple Myeloma with Involved Free Light Chains Exceeding 1000 mg/L at Diagnosis: Insights from an Indian Cohort.

Myeloma patients with high involved free light chains (iFLC) at diagnosis may exhibit a worse clinical course, independent of established prognostic factors. This study aimed to evaluate clinical and renal outcomes in Indian patients with baseline iFLC exceeding 1000 mg/L. All MM patients diagnosed between January 2021 and July 2023 with iFLC > 1000 mg/L were included with the primary and secondary objectives to describe overall survival (OS) and renal outcomes, respectively. Thirty-eight patients (M: F = 26:12) with a median age of 63 years were included. Renal impairment (eGFR < 40 ml/min) was present in 24 (63%) patients with a median eGFR of 9 (6-15.25). At diagnosis, median involved free light chain (iFLC) was 5262 mg/L (kappa: 1996 mg/L, lambda: 36 mg/dL). VCD was most frequent initial therapy (55%), followed by VRD (21%); 76% patients received Bortezomib. Ten patients (26%) required dialysis at presentation. At first reassessment after a median of 91 days, median eGFR was 36 ml/min/1.73m2. Of twenty assessable patients, one patient (15%) had partial renal response, and three (15%) each had complete and minimal response, respectively. After a median follow up of 38 months, median OS was 76 months (1- and 3-year survival: 78% and 54%). Dialysis independence was achieved in 60% of patients. There was no correlation between final serum creatinine and baseline value of iFLC. This study describes the first Indian data on patients with myeloma and high initial iFLC (> 1000 mg/L). Compared to published data, we observed a higher frequency of renal impairment, dialysis requirement, and shorter OS. Our data suggests a potential role between high iFLC and clinial outcomes, warranting further evaluation as its role as an independent risk factor.