Time to treatment initiation and clinical, toxicity, and supportive care outcomes in multiple myeloma: A real-world Epic Cosmos analysis.

Abstract

e19559 Background: Timely initiation of systemic therapy is critical in multiple myeloma (MM), yet real-world variation in time to treatment initiation (TTI) and its association with clinical outcomes, treatment-related toxicities, and supportive care utilization remain incompletely characterized. Methods: We conducted a retrospective cohort study using the Epic Cosmos database (2015–2025). Adults with MM were identified using ICD-10-CM code C90. TTI was defined as days from MM diagnosis to first exposure to systemic anti-myeloma therapy, including proteasome inhibitors, immunomodulatory drugs, or anti-CD38 monoclonal antibodies. Patients were stratified into TTI < 30 days (n = 90015), 30–60(n = 81190), and > 60 days(119,245). Primary outcomes included mortality, infection (sepsis or pneumonia), AKI within 30 days, DVT/PE, and bone marrow transplant (BMT). Secondary outcomes included hemodialysis initiation, febrile neutropenia, thrombocytopenia, herpes zoster reactivation, and use of bone-protective therapy (zoledronic acid, pamidronate, or denosumab) and antiviral prophylaxis (acyclovir/valacyclovir). Outcomes are presented as unadjusted percentages with 95% confidence intervals. Results: Mortality demonstrated a U-shaped association with TTI, occurring in 22.99%, 21.32%, and 21.32% of patients in the < 30-day, 30–60-day, and > 60-day cohorts, respectively. Infection rates were 16.42%, 17.11%, and 17.30%, while AKI < 30 occurred in 16.01%, 16.38%, and 16.49%. BMT utilization was highest in the 30–60-day cohort (19.14%) compared with < 30 days (18.28%) and > 60 days (18.21%). VTE rates increased modestly with delayed treatment (9.39%, 9.82%, and 10.10%). HD occurred in 3.15%, 3.08%, and 3.07% of patients. Febrile neutropenia occurred in 17.15%, 18.03%, and 17.55%, thrombocytopenia in 13.34%, 13.93%, and 13.86%, and herpes zoster reactivation in 1.21%, 1.29%, and 1.42%. Antiviral prophylaxis use was highest in the 30–60-day cohort (91.25%) compared with < 30 days (88.48%) and > 60 days (88.23%). Bone-protective therapy use was also highest in the 30–60-day cohort (31.68%) versus < 30 days (28.90%) and > 60 days (23.79%). Conclusions: In this large real-world analysis, initiation of systemic therapy within 30–60 days of MM diagnosis was associated with lower mortality, higher transplant utilization, and greater use of guideline-recommended supportive care compared with both earlier and delayed treatment initiation. Patients treated within 30 days appeared to represent a higher-acuity phenotype, while delays beyond 60 days were associated with lower supportive care uptake and higher thrombotic risk. These findings suggest that time to treatment initiation may reflect both disease severity and care delivery quality, and identify a potentially actionable window to optimize treatment pathways and supportive care in multiple myeloma.