VANCOUVER, British Columbia—Half of the approved dose for cytomegalovirus (CMV) prophylaxis in solid organ transplant recipients is just as effective as the approved dose and is safer, new findings suggest.

“We found that if you give a patient 450 mg [daily] instead of 900 mg, you can get less side effects and similar efficacy compared to the approved 900 mg,” said investigator Andre Kalil, MD, Associate Professor of Medicine and Director of the Transplant Infectious Diseases Program at the University of Nebraska Medical Center in Omaha.

Dr. Kalil and his colleagues conducted a meta-analysis of controlled studies evaluating the prevention of CMV disease following solid organ transplantation. The meta-analysis included 12 studies evaluating valganciclovir 900 mg daily and eight studies evaluating valganciclovir 450 mg daily. The studies of valganciclovir 900 mg enrolled a total of 1,543 patients; the studies of valganciclovir 450 mg daily enrolled 1,531 patients.

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Compared with controls, recipients of valganciclovir 900 mg had a 6% increased risk of CMV disease and recipients of the 450 mg dose had a 23% decreased risk, but the differences in risk between the valganciclovir and control arms were not significant, the researchers reported at the 48th Annual Meeting of the Infectious Diseases Society of America. However, compared with controls, the risk of leucopenia was significantly increased fivefold in the 900 mg group versus a non-significant 1.58 times in the 450 mg group. The risk of acute allograft rejection increased by 1.7 times in the 900 mg group but decreased by 0.77 times in the 450 mg group compared with controls.

Compared with patients who received the 450 mg dose, those who received the 900 mg dose had a threefold significant increased risk of leucopenia and a twofold significant increased risk of acute rejection. The results were similar even when they were adjusted for allograft type and immunosuppressive regimen.

“I think we have enough strong evidence [such] that we should start to think about switching the regimen from 900 mg to 450 mg,” Dr. Kalil told Renal & Urology News. “However, ideally speaking, we would like to see a prospective study looking at the two regimens head-to-head in a randomized clinical trial.”

Switching renal transplant recipients to the lower dose could result in a huge cost savings, Dr. Kalil said. “In the United States, an average monthly retail cost of valganciclovir would be in the range of $2,000 to $3,000.  So if you only have to buy half the drug, it is simple math. You would definitely decrease costs as well as serious side effects like leucopenia,while maintaining similar efficacy.”