Photo by Bill Branson
Doctor vaccinating a patient
ORLANDO, FL—Results of a phase 3 trial suggest an inactivated varicella zoster virus (VZV) vaccine known as V212 can reduce the risk of herpes zoster (HZ) in patients who have undergone autologous hematopoietic stem cell transplant (HSCT).
V212 reduced the hazard rate of HZ by an estimated 64% compared to placebo.
The vaccine also reduced the incidence of moderate-to-severe HZ pain and other HZ-related complications, such as hospitalization.
The overall incidence of adverse events (AEs) and the incidence of serious AEs were similar among vaccinated patients and those who received placebo.
Drew J. Winston, MD, of the University of California Los Angeles Medical Center, presented these results as one of the “Best Abstracts” at the 2017 BMT Tandem Meetings (abstract 6). The trial was sponsored by Merck, the company developing V212.
Treatment
This randomized, double-blind trial enrolled 1230 patients age 18 and older who were undergoing HSCT for any indication and had a history of varicella infection and/or were seropositive for VZV antibody.
The patients were randomized to receive:
- A 4-dose regimen of V212 (n=560) from a consistency lot (a lot having a targeted potency as required by regulators in order to demonstrate that the vaccine can be manufactured consistently)
- A 4-dose regimen of V212 (n=106) from a high-antigen lot (a lot having a higher antigen potency added to assess the safety profile of V212)
- Placebo (n=564).
Randomization was stratified by age (< 50 years vs ≥ 50 years) and by intended duration of post-transplant antiviral prophylaxis (≤3 months vs >3 to 6 months).
Dose 1 of V212 or placebo was given within approximately 30 days before HSCT, and doses 2, 3, and 4 were given approximately 30, 60, and 90 days after HSCT.
Patient characteristics
The median patient age was 57 (range, 19-76) for the consistency lot group, 56 (range, 21-75) for the high-antigen lot group, and 56 (range, 19-79) for the placebo group.
Underlying diseases were non-Hodgkin lymphoma (42%, 40%, and 44%, respectively), Hodgkin lymphoma (10%, 9%, and 9%, respectively), multiple myeloma (44%, 47% and 41%, respectively), acute leukemia (2%, 1%, and 2%, respectively), and “other” diseases (2%, 3% and 4%, respectively).
Roughly 30% of patients in each group received anti-viral agents for 3 months or less after HSCT. Twenty percent to 25% received antiviral therapy for more than 3 months to 6 months.
Thirty-seven percent to 40% received antiviral agents for more than 6 months. And 7% to 12% of patients did not receive any antiviral therapy.
HZ incidence
The average follow-up time for HZ surveillance was approximately 2.3 years (median: 2.6 years) post-vaccination.
Confirmed HZ occurred in 42 of the 538 patients who received V212 from a consistency lot and 113 of the 535 patients who received placebo. (Patients receiving V212 from a high-antigen lot were only included in the safety analysis.)
The estimated efficacy of V212 was 63.8% after adjustment for patient age and the duration of antiviral prophylaxis. Vaccine efficacy against HZ was defined as the relative reduction of hazard rate of HZ in vaccine recipients compared with placebo recipients.
The vaccine met the pre-specified criterion for success, as the lower bound of the 95% confidence interval (CI) was greater than 25%. The 95% CI was 48.4% to 74.6% (P<0.0001).
“The study demonstrates that the inactivated varicella vaccine is very effective for preventing herpes zoster after autologous stem cell transplantation,” Dr Winston said.
Pain, PHN, and other complications
V212 also reduced the incidence of moderate-to-severe HZ pain—according to the Zoster Brief Pain Inventory (ZBPI) score—by an estimated 69.5% (95% CI, 0.490-0.818).
Nineteen patients in the V212 consistency lot group had moderate-to-severe pain, as did 61 placebo-treated patients.
V212 conferred an estimated 83.7% (95% CI, 0.446-0.952) reduction in the incidence of post-herpetic neuralgia (PHN). Three patients in the V212 consistency lot group and 18 patients in the placebo group had PHN.
PHN was defined as pain in the area of the HZ rash with a “worst pain in the last 24 hours” score of 3 or greater (on a 0-10 scale) on the ZBPI that persists or appears 90 days or beyond after HZ rash onset following HSCT.
Patients who received V212 also saw an estimated 73.5% (95% CI, 0.498-0.860) reduction in “other” HZ complications. Twelve patients in the V212 consistency group and 44 in the placebo group had such complications.
“Other” complications included hospitalization or prolongation of hospitalization due to HZ, disseminated HZ (including disseminated HZ rash or VZV viremia), visceral HZ, ophthalmic HZ, neurological impairment due to HZ, and the administration of intravenous acyclovir therapy for the treatment of HZ post-HSCT.
Safety
All patients who received at least 1 dose of the vaccine or placebo and had follow-up data were included in the safety analysis. Patients were followed for AEs up to 28 days after the fourth vaccination dose.
AEs occurred in 97% of patients who received the vaccine (consistency and high-antigen groups assessed together) and 96.9% of placebo-treated patients. Vaccine-related AEs occurred in 32.6% and 12.6%, respectively.
“Of course, in this population of autologous stem cell transplant patients, adverse events of any type were very common in almost all patients,” Dr Winston said. “However, vaccine-related adverse events were greater in the vaccine recipients compared to the placebo patients, but this was primarily due to an increased incidence of injection-site adverse events in the vaccine recipients.”
Injection-site reactions occurred in 191 vaccinated patients and 36 placebo-treated patients.
The most common systemic AEs—in vaccinated and placebo-treated patients, respectively—were diarrhea (60.1% and 61.9%), nausea (56.5% and 57.8%), pyrexia (49.8% and 46.9%), mucosal inflammation (39.7% and 41.7%), thrombocytopenia (36.4% and 38.4%), febrile neutropenia (33.9% and 28.3%), vomiting (32.6% and 36.6%), anemia (26.6% and 24.4%), neutropenia (25.1% and 23.5%), decreased appetite (23.1% and 23.8%), fatigue (21.8% and 20.7%), hypokalemia (21.3% and 19.9%), and constipation (16.1% and 18.4%).
The incidence of serious AEs was 32.9% in vaccinated patients and 32.7% in the placebo group. The incidence of serious vaccine-related AEs was 0.8% and 0.9%, respectively.
The most common serious AEs—in vaccinated and placebo-treated patients, respectively—were infection (12.3% and 11.9%), relapsed malignancy (7.8% for both), febrile neutropenia (5.3% and 4.9%), pyrexia (3.2% and 4.0%), gastrointestinal disorders (3.2% and 3.6%), respiratory failure (2.7% and 2.2%), cardiac disorders (1.7% and 1.6%), and mucositis (1.2% and 0.9%).
Death occurred in 6.2% of vaccinated patients and 6.3% of placebo-treated patients. Three percent and 3.1%, respectively, discontinued the study due to AEs.
