NMDP Data Shows Mismatched Donors Yield Comparable Patient Outcomes — National Marrow Donor Program (NMDP)

Event summary

NMDP-sponsored ACCESS trial data presented at the 2026 Tandem Meetings show comparable patient-reported outcomes and survival across levels of genetic mismatch in hematopoietic cell transplants.
One-year post-transplant overall survival exceeded 80% across all match levels, with 86% for <7/8 mismatches and 79% for 7/8 mismatches.
Chronic graft-versus-host disease (GVHD) was identified as the primary factor impacting quality of life, regardless of donor match level.
Infection burden remains a key safety concern, with 68% of patients experiencing at least one grade 2 or higher infection within the first year post-transplant.

The big picture

The ACCESS trial results challenge the long-held belief that exact genetic matching is critical for successful hematopoietic cell transplants. This shift could significantly expand donor options, particularly for patients from diverse ancestral backgrounds who historically faced challenges in finding suitable donors. The findings also underscore the importance of addressing infection risks and GVHD to further enhance patient outcomes.

What we're watching

Infection Risk Management: The pace at which NMDP can reduce infection risk through optimized post-transplant cyclophosphamide (PTCy) dosing strategies.
GVHD Prevention: How advancements in minimizing chronic GVHD will further improve quality of life for transplant recipients.
Donor Access Expansion: Whether the increased use of mismatched unrelated donors (MMUD) can sustain comparable outcomes while expanding access to transplantation.