Utilization of Autologous Stem Cell Transplantation in Older Patients with Newly Diagnosed Multiple Myeloma

Historically, high-dose therapy in combination with autologous stem cell transplants (ASCT) for multiple myeloma (MM) was reserved for younger patients. In more recent years, the use of ASCT has expanded in the older population. However, there is still limited data on the utilization and efficacy of ASCT in older patients, particularly those over the age of 75.

To further evaluate this issue, we retrospectively analyzed all patients with newly diagnosed MM between the ages of 75-78, the institutional cutoff for ASCT eligibility, that were referred to the stem cell transplant unit at our institution for consultation from the years 2012-2018. Baseline characteristics, anti-myeloma treatments, and patient outcomes were abstracted through chart review.

Seventy-five patients were referred to our institution. 71% were male, 29% female. 39% patients were considered ineligible for ASCT by the consulting transplant physician. Most patients were considered transplant ineligible due to comorbidities or poor performance status. Of the 46 patients eligible for ASCT, 52% underwent the procedure during their first-line therapy. The majority of those patients received reduced intensity melphalan (140 mg/m²) while 2 patients received conventional dosing (200 mg/m²). The other 22 patients eligible for ASCT declined or elected to defer the procedure and to be treated with conventional therapy. The characteristics of these three groups were similar and are detailed in Table 1.

After a median follow-up of 30 months, 25% of the patients had expired. Estimated median overall survival (OS) was 71.3 months (unable to quantitate 95% CI) for all patients. Compared to transplant eligible patients, regardless of transplant receipt, those who were transplant ineligible had a 186% increase risk for death (HR 2.86; 95% CI 1.12-7.35; p = 0.029). There was also a notable trend for longer OS in those who underwent ASCT compared to those who were eligible but declined the procedure, but it was not statistically significant (HR 0.36; 95% CI 0.10-1.28; p = 0.114).

At a transplant center, two-thirds of patients referred for newly diagnosed MM between the ages 75-78 were considered eligible for ASCT and one-third underwent the procedure. Outcomes were better for patients eligible for ASCT, regardless of whether they underwent the procedure. There was also a trend for better OS in patients who underwent the procedure compared to those who declined. While small sample sizes and the retrospective nature of the study limit our ability to draw conclusions, it appears that ASCT has an OS benefit among patients age 75-78.

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