Clinical Trials

The influenza virus is a significant cause of morbidity in adult solid organ transplant (SOT) recipients. However, these individuals show a suboptimal response to vaccines including the standard-dose (SD) inactivated influenza vaccine (IIV). Recent studies have investigated two strategies to overcome poor immune responses in SOT recipients: (1) administration of high-dose (HD)-IIV compared to SD-IIV and (2) two doses of SD-IIV compared to one dose of SD-IIV in the same influenza season. The first study compared HD-IIV vs. SD-IIV in adult SOT and noted HD-IIV was safe and reported higher immunogenicity; however, the median post-transplant period was 38 months. In another phase II trial of adult SOT recipients, two doses of SD-IIV a month apart compared to one-dose SD-IIV revealed increased immunogenicity, with a median post-transplantation period of 18 months. Therefore, these studies lack evaluation in the early post-transplantation period in this vulnerable population when influenza disease is most severe. The administration of two-doses of HD-IIV in the same influenza season has also not been studied in SOT recipients. Moreover, the vast majority of SOT influenza vaccinations studies have not substantively evaluated prolonged immunogenicity. Thus, the optimal immunization strategy for SOT recipients less than 12 months post-transplant is poorly-defined. In addition, the immunologic predictors and correlates of influenza vaccine immunogenicity in SOT recipients have not been defined. The investigators hypothesize that adult solid organ transplant recipients that are 1-11 months out from transplant and are receiving high-dose inactivated influenza vaccine will have higher hemagglutination inhibition (HAI) geometric mean titers to influenza A antigens compared to adult SOT recipients receiving standard-dose inactivated influenza vaccine. To test this hypothesis and address the above critical knowledge gaps, The investigators propose to conduct a phase II multicenter randomized controlled trial comparing either two doses HD-IIV, two doses of SD-IIV, or one-dose of HD-IIV in adult kidney, heart, and liver SOT recipients 1-11 months post-transplantation. The results of this study will address significant gaps in knowledge regarding influenza vaccine strategies and immune responses in adult SOT recipients and will guide vaccine recommendations in this vulnerable population.

Brief Summary:

The primary objective of the study is to assess the safety and tolerability of REGN5459 (Part A) or REGN5458 (Part B) as monotherapy in patients with chronic kidney disease (CKD) who need kidney transplantation and are highly sensitized to human leukocyte antigen (HLA).

The secondary objectives of the study are to determine/assess the following for REGN5459 (Part A) or REGN5458 (Part B):

• Dose regimen(s) that result in a clinically meaningful reduction of anti-HLA alloantibody levels
• Effect on calculated panel-reactive antibody (cPRA) levels
• Time to maximal and clinically meaningful reduction in anti-HLA alloantibody levels
• Duration of the effect of study drug on the reduction of anti-HLA alloantibodies
• Effect on circulating immunoglobulin (Ig) classes (isotypes)
• Pharmacokinetics (PK) properties
• Immunogenicity

Lung allograft recipients have a higher burden of influenza disease and greater associated morbidity and mortality compared with healthy controls. Induction and early maintenance immunosuppression is thought to impair immunogenicity to standard dose inactivated influenza vaccine. This early post-transplant period is when immunity is most desirable, since influenza disease during this time frame is associated with adverse consequences. Thus, strategies to reduce severe influenza disease in this highly susceptible population are critical. No trials in lung transplant recipients have evaluated two doses of HD-IIV within the same influenza season as a strategy to improve immunogenicity and durability of influenza prevention. Furthermore, no influenza vaccine trials have focused on enrollment of subjects at early post-transplant timepoints. Very few studies have been performed in solely lung allograft recipients. Immunosuppression intensity is highest in lung patients, thereby limiting comparisons to recipients of heart, liver, and kidney transplants. Therefore, studies to assess both HD-IIV and two-dose strategies in the same influenza season in post-lung transplant recipients are greatly needed.

The central hypothesis of our proposal is that lung allograft recipients who are 1-35 months post-transplant and receiving two doses of HD-quadrivalent inactivated influenza vaccine (QIV) will have higher HAI geometric mean titers (GMT) to influenza antigens compared to those receiving two doses of SD-QIV. To test this hypothesis and address the above critical knowledge gaps, we propose to conduct a phase II, multi-center, randomized, double-blind, controlled immunogenicity and safety trial comparing the administration of two doses of HD-QIV to two doses of SD-QIV in lung allograft recipients 1-35 months post-transplant. The results of this clinical trial will address significant knowledge gaps regarding influenza vaccine strategies (e.g., one vs. two doses and HD-QIV vs. SD-QIV) and immune responses in lung transplant recipients and will guide vaccine recommendations during the post-transplant period.