CMV reactivation post allogeneic stem cell transplantation decreases relapse risk and survival, and increases NRM - a...

Refractory/resistant CMV post AlloHSCT remains challenging. 1147 consecutive patients transplanted at PMH were reviewed, including 472 patients (41.2%) who received dual ATG-PTCy GVHD prophylaxis. This cohort reflects a predominantly in vivo T-cell-depleted transplant population in the pre-letermovir era. 54.9% had at least one CMV reactivation, and 4.1% were defined as refractory and 26.3% as probably refractory. Patients without CMV reactivation had better OS compared at 1-, 3-, and 5-years (67.3% vs. 60.8%, 56.7% vs. 46.7%, and 50.1% vs. 44.0%, p = 0.02), but NRM was higher (29.5%, 20.1%, 37.6% vs. 24.4%, 39.1%, 27.3% p < 0.001), and leukemic relapse was lower (19.6% vs. 24.5%, p = 0.03), in individuals with myeloid malignancy. Refractory CMV infection had higher CMV-related mortality compared to those responding to CMV treatment, (11.5% vs 3.9% at one-year p = 0.026). Probable-refractory patients experienced 6.0% CMV-related mortality (p = 0.40 vs not refractory, p = 0.13 vs. refractory). CMV reactivation was associated with lower relapse risk in patients with myeloid malignancy, although the biological basis of this association remains uncertain. Refractory CMV increases CMV-related mortality, but probable refractory CMV does not increase mortality risk.