Vitamin C can increase the activity of cellular proteins known as TET enzymes, which help regulate whether certain genes are switched on or off. Reduced TET enzyme activity is a common feature in some blood cancers, prompting researchers to investigate whether vitamin C supplements might benefit people at risk of developing these diseases.
The findings come from a phase 2 clinical trial published online by Wiley in CANCER, a peer-reviewed journal of the American Cancer Society.
Testing Vitamin C in People at Risk of Blood Cancer
The randomized, double-blind, placebo-controlled EVITA trial included 109 participants in Denmark and the United States. All had either a blood disorder with the potential to become cancerous or a low-risk form of blood cancer.
At the beginning of the study, 55 participants were randomly assigned to take oral vitamin C (1,000 mg/day), while 54 received a placebo. Treatment continued for 12 months.
The main outcome researchers were looking for was whether vitamin C affected the growth rate of precancerous or cancerous cells. On that measure, the vitamin C and placebo groups were similar.
However, researchers did observe other differences. People taking vitamin C showed changes in inflammatory signaling that align with better outcomes. They also experienced fewer cases of anemia, pneumonia, acute aseptic arthritis, and internal bleeding, although gastrointestinal problems were more common in the vitamin C group.
A Possible Survival Signal
At a median follow-up of 33.6 months (nearly 3 years) in the intention-to-treat population, 35 participants had died. Of those deaths, 24 occurred in the placebo group and 11 occurred in the vitamin C group.
An exploratory analysis found that participants assigned to vitamin C were more likely to survive during follow-up than those who received placebo. Because this was an exploratory finding, researchers say it must be tested and confirmed in a larger phase 3 clinical trial before firm conclusions can be drawn.
“The EVITA trial gives us a strong rationale to continue exploring if and how vitamin C might benefit people with certain pre-cancer or early-stage blood cancers. More work is needed but we are cautiously optimistic that these findings could inform future strategies to intercept leukemia development,” said co-senior author Peter A. Jones, PhD, DSc (hon), of Van Andel Institute, in Grand Rapids, Michigan. Jones is co-leader of the Van Andel Institute-Stand Up To Cancer (VAI-SU2C) Epigenetics Dream Team, which led the EVITA trial.
Larger Trial Needed
Researchers emphasized that the results are encouraging but are not yet strong enough to support new treatment recommendations.
“We are encouraged by our findings and what they ultimately could mean for people with these early-stage blood disorders. 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,” added co-senior author Kirsten Grønbæk, MD, PhD, of Rigshospitalet, Copenhagen University Hospital in Denmark. Grønbæk is a longtime member of the VAI-SU2C Epigenetics Dream Team.