Breaking geographic barriers in a Mexican ambulatory transplant program: Early outcomes in a diverse national and international cohort

Abstract Background: Access to hematopoietic cell transplantation (HCT) in Latin America remains highly centralized. The lack of regional transplant centers, travel logistics, and socioeconomic barriers contribute to inequities in care. Ambulatory HCT models have emerged as safe and cost-efficient alternatives; however, patients referred from distant institutions may face increased risks related to travel and care coordination. This study aimed to evaluate early post-transplant outcomes and potential disparities among patients treated at our ambulatory transplant center in Mexico, serving both national and international populations. Methods: We conducted a retrospective cohort study of all pediatric and adult patients who underwent HCT between January 2020 and December 2024 at our single-center, FACT-accredited, outpatient-based transplant program in Monterrey, Mexico. Variables included age, sex, geographic origin, diagnosis, HCT type, time from diagnosis to HCT (“time to HCT”), time from first visit to transplant (“door-to-HCT”), and follow-up duration at the center. Patients were stratified as local (within the Monterrey metropolitan area) or non-local (outside the metro area, national or international). Early outcomes included the cumulative incidence of non-relapse mortality (NRM) and graft failure (GF), estimated using competing risk models. For NRM, relapse-related death and second transplant were considered competing events; for GF, death from any cause and second transplant were considered competing events. Overall survival (OS) was measured from day 0 of HCT to last contact. Results: A total of 489 HCTs performed in 476 patients were included. Median age was 30 years (range, 1–79), and 60.3% were male. The most frequent diagnoses were acute leukemia (43.4%), multiple myeloma (18.2%), lymphoma (18%), bone marrow failure (10.2%), and other conditions (10.2%). Haploidentical HCT was the most common (208, 42.5%), followed by autologous (204, 41.7%) and matched allogeneic (77, 15.7%). Median time to HCT was 11.8 months (IQR, 6.1–24.5), door-to-HCT was 24 days (IQR, 15–54), and follow-up at the center was 5 months (IQR, 2–13). Patients came from 30 of 32 Mexican states and nine countries across the Americas, mainly Guatemala (12 patients, 2.5%), Paraguay (7, 1.4%), and Honduras (5, 1%). Patients were classified as local (155, 31.6%) and non-local (334, 68.3%), including 299 (61.1%) national and 35 (7.2%) international patients. Compared to local patients, non-locals were older (32 years [IQR, 19–51] vs. 22 [IQR, 12–52]), had shorter door-to-HCT times (22 days [IQR, 14–41] vs. 38 [IQR, 18–71]), and shorter follow-up duration at the center (4 months [IQR, 1–9] vs. 8 [IQR, 3–19]); all with p<0.01. No significant differences were observed in sex, diagnosis, HCT type, or time to HCT between groups. The cumulative incidence of NRM at day 100 was 1.0% (95% CI, 0–2.4) for autologous, 5.3% (95% CI, 0.2–10.4) for matched allogeneic, and 14.2% (95% CI, 9.4–19.1) for haploidentical transplants. Cumulative incidence of GF at day 100 was 0% for autologous, 2.7% (95% CI, 0–6.3) for matched, and 6.9% (95% CI, 3.4–10.4) for haploidentical HCT. Neither NRM nor GF differed significantly by geographic origin. Compared to local patients, the hazard ratio (HR) for NRM was 1.13 (95% CI, 0.64–1.99; p = 0.67) for national patients and 0.83 (95% CI, 0.25–2.77; p = 0.76) for international patients. For GF, the HR was 1.14 (95% CI, 0.42–3.08; p = 0.79) and 2.71 (95% CI, 0.68–10.81; p = 0.16), respectively. One-year OS was 97% (95% CI, 94–100) for autologous, 70.8% (95% CI, 60.5–82.9) for matched, and 68.7% (95% CI, 62.2–76) for haploidentical HCT. OS did not differ by geographic origin (log-rank p = 0.3). Conclusions: Our ambulatory transplant center safely delivers HCT to a geographically diverse population, including nearly all Mexican states and nine American countries, with over two-thirds of patients coming from outside the metropolitan area. Despite longer travel distances and greater logistical challenges, non-local patients, including those from abroad, experienced early outcomes comparable to those of local patients. These findings reinforce the safety and feasibility of ambulatory transplant programs. Strengthening communication and care coordination with referring centers is essential to sustaining long-term outcomes and reducing geographic disparities in access to curative therapies.