Oral Vitamin C Active in Clonal Cytopenia of Undetermined Significance

MONDAY, Sept. 21, 2026 (HealthDay News) — For patients with clonal cytopenia of undetermined significance (CCUS) or lower-risk myeloid malignancies, oral vitamin C is safe and biologically active, according to a study published online Sept. 21 in Cancer.

Stine Ulrik Mikkelsen, M.D., Ph.D., from Copenhagen University Hospital-Rigshospitalet in Denmark, and colleagues conducted a double-blind, randomized, placebo-controlled, phase 2 trial involving adults with CCUS or lower-risk myeloid malignancies not receiving anticancer therapy. Participants were randomly assigned to receive oral vitamin C (1,000 mg/day) or placebo for 12 months (55 and 54 participants, respectively).

The researchers observed no significant difference between the groups in the primary end point of median clonal growth rate, but secondary outcomes included differences in inflammatory cytokine trajectories and fewer serious adverse events in the vitamin C group versus placebo group (33 versus 57 percent). Overall survival was significantly longer with vitamin C in an exploratory analysis (hazard ratio, 0.35).

“We are encouraged by our findings and what they ultimately could mean for people with these early-stage blood disorders,” co-senior author Kirsten Grønbæk, M.D., Ph.D., also from Rigshospitalet, said in a statement. “Although it is too soon to make recommendations based on our results, we are hopeful that a larger study will give us more definitive answers.”

Several authors disclosed ties to the biopharmaceutical industry.

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