Maribavir, an investigational antiviral agent with a novel mechanism of action, was superior to other antiviral strategies at clearing cytomegalovirus (CMV) viremia and controlling symptoms in hematopoietic cell or solid-organ transplant recipients, results of a phase 3 clinical trial showed.
CDC
CMV viremia clearance at study week 8 was seen in 55.7% of all patients randomized to receive maribavir, compared with 23.9% for patients assigned to receive investigator-assigned therapy (IAT), Francisco Marty, MD, from the Dana-Farber Cancer Institute in Boston reported at the Transplant & Cellular Therapies Meetings.
“Maribavir’s benefit was driven by lower incidence of treatment-limiting toxicities, compared with IAT,” he said a late-breaking abstract session during the meeting held by the American Society for Blood and Marrow Transplantation and the Center for International Blood and Marrow Transplant Research.
“Available anti-CMV antivirals are limited by development of resistance and toxicities, particularly myelosuppression with the use of valganciclovir and nephrotoxicity with the use of foscarnet and cidofovir. Alternative treatment options are required to address this unmet medical need,” he said.
Maribavir inhibits the CMV UL97 protein kinase and is thought to affect several critical processes in CMV replication, including viral DNA synthesis, viral gene expression, encapsidation, and egress of mature capsids from the nucleus.
Details of trial
In the phase 3 SHP620-30e trial (NCT02931539), Dr. Marty and colleagues enrolled patients with relapsed or refractory CMV infections after hematopoietic cell transplant (HCT) or solid-organ transplant (SOT) and after stratification by transplant type and screening CMV DNA level randomly assigned them on a 2:1 basis to receive either maribavir 400 mg twice daily (235 patients) or IAT (117 patients), consisting of either ganciclovir/valganciclovir, foscarnet, cidofovir, or combined foscarnet and val/ganciclovir.
The primary endpoint of viremia clearance at 8 weeks was defined as plasma CMV DNA less than 137 IU/mL in two consecutive tests at a central laboratory at least 5 days apart beginning at the end of week 8.
The trial met its primary endpoint, with a viremia clearance rate of 55.7% with maribavir versus 23.9% with IAT.
The viremia clearance rates were similar in each of the transplant groups: 55.9% versus 20.8%, respectively, in patients who underwent HCT, and 55.6% versus 26.1% in patients who underwent SOT (P < .001).
Clearance rates among patients with CMV DNA below 9,100 IU/mL at baseline were 62.1% with maribavir versus 24.7% with IAT. Among patients with baseline CMV DNA of 9100 IU/mL or above, the respective rates were 43.9% versus 21.9%.
CMV viremia clearance continued from week 8 to week 16 in 18.7% of patients assigned to maribavir and to 10.3% of patients randomized to IAT (P < .013).
The median time to first CMV viremia clearance as 22 days with maribavir versus 27 days with IAT (P = .039).
All-cause mortality was similar between the groups, at 11.5% versus 11.1%, respectively.
The incidences of serious and severe treatment-emergent adverse events (TEAE) were 38.5% and 32.1%, respectively, in the maribavir group, and 37.1% and 37.9% in the IAT group.
Any TEAE leading to study drug discontinuation was less common with maribavir, occurring in 13.2% of patients, compared with 31.9% of patients on IAT. Serious TEAEs leading to drug discontinuation occurred in 8.5% versus 14.7%, respectively.
Serious TEAEs leading to death occurred in 6.8% of patients on maribavir versus 5.2% of those on IAT.