P-171: The changing landscape of peri-transplant adverse events with HDT/ASCT and the impact on long term outcomes for myeloma patients

Introduction: High dose therapy followed by autologous stem cell transplant (HDT/ASCT) remains standard of care for newly diagnosed transplant-eligible patients with myeloma. Given the morbidity and mortality associated with HDT/ASCT, the decision to proceed with HDT/ASCT necessitates a careful discussion and shared decision making of risks vs benefits. With the changing landscape of improved supportive care, we reviewed the rates of both immediate and long-term impact of peri-transplant complications.

Methods: Variables of interest were extracted from the Clinical Data Warehouse (CDW), a Structured Query Language (SQL) database. A tiered algorithmic approach was developed to automate the extraction of data elements from the CDW utilizing SQL scripts, which were manually validated. Neutropenic fever rates (ASCO definition), microbiology, radiology, and culture data were all used for our automated extraction. We used two time periods (decade 1: 2000-2010, decade 2: 2011-2021) to evaluate the changes by era. All values were reported as decade 1 vs decade 2, respectively.

Results: For the 2,970 patients that underwent HDT/ASCT from 2000-2021, 614 (20.7%) received HDT/ASCT in decade 1. Median age at transplant was 58.1 (range, 27.1-77.4) vs 62.3 years (range, 16.8-79.9), p< 0.001. Patients ≥ 70 were transplanted more in decade 2 (5.9% vs 17.4%, p< 0.001). The time from diagnosis to HDT/ASCT was shorter [10.6 (2-157) vs 6.7 months (1-231), p< 0.0001] and higher rates of ≥VGPR pre-transplant were achieved in decade 2 (12.5% vs 57.3%, p< 0.001). 71.6% of patients received melphalan 200 mg/m2.

C.diff occurred in 5.5% and respiratory infections in 3.3%, not different by decade. Increased incidence of SVT (4.6% vs 7.4%, p< 0.006), bacteremia (5 vs 8.9%, p< 0.001), neutropenic fevers (64.7 vs 82.4, p< 0.001), ICU transfers (2.6 vs 5.9%, p< 0.001) occurred in decade 2. Despite transplanting older patients, the rate of 30-day readmits (10.4 vs 8%; p=0.037), 30-day mortality (1.5% vs 0.7%, p=0.05) and 100-day mortality (3.6% vs 1.6%, p=0.002) decreased in decade 2. The OS improved in decade 2 (7.2 vs 10.5 years, p< 0.001). Developing bacteremia, c. diff, and respiratory infections peri-transplant as well as transplant age ≥70 did not have any impact on OS, however developing SVT (9.25 vs 6.6 years, p< 0.001) and ICU transfer peri-transplant (9.2 vs 6.3 years, p< 0.001) are associated with shorter OS.

Conclusions: More elderly patients underwent HDT/ASCT in decade 2 and have gained the survival advantage the decade had to offer both from the benefit of modern induction therapies as seen by increased ≥VGPR rates pre-transplant as well as HDT/ASCT itself. Transplanting elderly patients did not have any impact on long term survival. Developing SVT and ICU transfer are associated with less optimal outcomes. The 30-day, 100-day mortality, re-admit rates have all improved in the last decade, allowing room for a meaningful discussion with patients favoring HDT/ASCT.