Overall mortality in the 109 patients from these subcohorts from SOLSTICE was lower, compared with mortality reported for similar populations treated with conventional therapies used to treat relapsed or refractory (R/R) CMV, according to findings presented in April at the annual meeting of the European Society for Bone and Marrow Transplantation.
“These results, in addition to the superior efficacy in CMV clearance observed for maribavir in SOLSTICE provide supportive evidence of the potential for the long-term benefit of maribavir treatment for post-transplant CMV infection,” Ishan Hirji, of Takeda Development Center Americas, and colleagues reported during a poster session at the meeting.
A retrospective chart review of the 41 hematopoietic stem cell transplant (HSCT) patients and 68 solid organ transplant (SOT) patients randomized to receive maribavir showed an overall mortality rate of 15.6% at 52 weeks after initiation of treatment with the antiviral agent. Among the HSCT patients, 14 deaths occurred (34.1%), with 8 occurring during the study periods and 6 occurring during follow-up. Among the SOT patients, three deaths occurred (4.4%), all during follow-up chart review.
Causes of death included underlying disease relapse in four patients, infection other than CMV in six patients, and one case each of CMV-related factors, transplant-related factors, acute lymphoblastic leukemia, and septic shock. Causes of death in the SOT patients included one case each of CMV-related factors, anemia, and renal failure.
“No patients had new graft loss or retransplantation during the chart review period,” the investigators noted.
The findings are notable as CMV infection occurs in 30%-70% of HSCT recipients and 16%-56% of SOT recipients and can lead to complications, including transplant failure and death. Reported 1-year mortality rates following standard therapies for CMV range from 31% to 50%, they explained.
Patients in the SOLSTICE trial received 8 weeks of treatment and were followed for 12 additional weeks. CMV clearance at the end of treatment was 55.7% in the maribavir treatment arm versus 23.9% in a control group of patients treated with investigator choice of therapy. As reported by this news organization, the findings formed the basis for U.S. Food and Drug Administration approval of maribavir in November 2021.
The current analysis included a chart review period that started 1 day after the SOLSTICE trial period and continued for 32 additional weeks.
These long-term follow-up data confirm the benefits of maribavir for the treatment of post-transplant CMV, according to the investigators, and findings from a separate study reported at the ESBMT meeting underscore the importance of the durable benefits observed with maribavir treatment.
For that retrospective study, Maria Laura Fox, of Vall d’Hebron Institute of Oncology, Barcelona, and colleagues pooled de-identified data from 250 adult HSCT recipients with R/R CMV who were treated with agents other than maribavir at transplant centers in the United States or Europe. They aimed to “generate real-world evidence on the burden of CMV infection/disease in HSCT recipients who had refractory/resistant CMV or were intolerant to current treatments.”
Nearly 92% of patients received two or more therapies to treat CMV, and 92.2% discontinued treatment or had one or more therapy dose changes or discontinuation, and 42 patients failed to achieve clearance of the CMV index episode.
CMV recurred in 35.2% of patients, and graft failure occurred in 4% of patients, the investigators reported.
All-cause mortality was 56.0%, and mortality at 1 year after identification of R/R disease or treatment intolerance was 45.2%, they noted, adding that the study results “highlight the real-world complexities and high burden of CMV infection for HSCT recipients.”
“With available anti-CMV agents [excluding maribavir], a notable proportion of patients failed to achieve viremia clearance once developing RRI [resistant, refractory, or intolerant] CMV and/or experienced recurrence, and were at risk of adverse outcomes, including myelosuppression and mortality. There is a need for therapies that achieve and maintain CMV clearance with improved safety profiles,” they concluded.
Both studies were funded by Takeda Development Center Americas, the maker of Levtencity. Ms. Hirji is an employee of Takeda and reported stock ownership. Ms. Fox reported relationships with Sierra Oncology, GlaxoSmithKline, Bristol Myers Squibb, Novartis, and AbbVie.