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Helocyte's Triplex Vaccine: Advancing CMV Treatment in Transplant Recipients


Cytomegalovirus (CMV) is a common opportunistic infection that poses significant risks to transplant recipients. To address this challenge, Helocyte, a subsidiary of Fortress Biotech, has been developing Triplex, a promising CMV vaccine. This article explores the latest developments in Triplex and its potential to enhance protective virus-specific immunity in stem cell donors, thus reducing the risk of CMV events in high-risk transplant recipients.

Understanding CMV and its Impact on Transplant Recipients

Cytomegalovirus (CMV) is a prevalent virus that infects a large percentage of the population. While it is often asymptomatic in healthy individuals, it can cause severe and life-threatening complications in people with weakened or uneducated immune systems, such as transplant recipients. Patients undergoing allogeneic stem cell and solid organ transplantation are particularly vulnerable to CMV-related complications.

According to the Center for International Blood and Marrow Transplant Research, over 9,000 unrelated and related bone marrow and cord blood transplants were performed in the United States in 2020. Additionally, preliminary data from the Organ Procurement and Transplantation Network reveals that over 40,000 organ transplants were performed in the United States in 2021, primarily kidney and liver transplant procedures. These statistics highlight the urgent need for effective CMV management strategies in transplant recipients.

Introduction to Triplex: A Novel CMV Vaccine

Triplex, developed by City of Hope and exclusively licensed to Helocyte in 2015, is a universal recombinant Modified Vaccinia Ankara viral vector vaccine. It has been engineered to induce a robust and durable virus-specific T cell response to three immuno-dominant CMV proteins: UL83 (pp65), UL123 (IE1), and UL122 (IE2). These proteins are linked to CMV complications in the post-transplant setting.

In previous Phase 1 and Phase 2 studies, Triplex demonstrated excellent safety, tolerability, and high immunogenicity. It has been dosed safely in over 150 patients and volunteers, and multiple ongoing clinical trials are exploring its efficacy in various scenarios.

Ongoing and Planned Clinical Trials

Triplex is currently the subject of several ongoing clinical trials, each focusing on different CMV-related challenges. These trials aim to evaluate Triplex's efficacy in different patient populations and explore its potential to control CMV and reduce viral load. Some of the ongoing and planned clinical trials include:

  1. Phase 1/2 Trial for CMV Control in Pediatric Recipients of HCT (NCT03354728): This trial aims to assess Triplex's ability to control CMV in pediatric recipients of hematopoietic cell transplantation (HCT).

  2. Phase 2 Trial for Reduction in Viral Load of HIV in Adults Co-infected with HIV and CMV (NCT05099965): This trial investigates the potential of Triplex to reduce the viral load of both HIV and CMV in adults with co-infection.

  3. Phase 1 Trial of Triplex in Combination with a Bi-specific CMV/CD19 Chimeric Antigen Receptor T Cell for the Treatment of Non-Hodgkin Lymphoma (NCT05432635): This trial explores the use of Triplex in combination with a bi-specific CMV/CD19 Chimeric Antigen Receptor T Cell for the treatment of Non-Hodgkin Lymphoma.

  4. Multicenter Phase 2 Trial for CMV Control in Recipients of Liver Transplant (U01AI163090, NCT# pending): This upcoming trial aims to evaluate Triplex's effectiveness in controlling CMV in recipients of liver transplants.

  5. Phase 2 Trial for CMV Control in Recipients of Kidney Transplant: This planned trial will focus on assessing Triplex's ability to control CMV in recipients of kidney transplants.

The National Cancer Institute Grant

Helocyte recently announced that the National Cancer Institute (NCI) has awarded a $3.22 million grant to City of Hope for clinical studies of Triplex. The grant will fund two multicenter, placebo-controlled, randomized Phase 2 studies. These studies will evaluate Triplex's potential safety, immunological response, and its ability to enhance CMV-specific T cell immunity in stem cell donors. The ultimate goal is to reduce the risk of CMV events in recipients of allogeneic hematopoietic cell transplant (HCT).

Advantages of Triplex over Existing Therapies

While current antiviral therapies have reduced CMV-related mortality in transplant recipients, they have limitations such as increased toxicity, delayed immune reconstitution, and late onset of CMV. In contrast, Triplex offers several advantages:

  1. Enhanced CMV-Specific T Cell Immunity: Triplex has shown promising results in enhancing the transfer of CMV immunity from HCT donors to high-risk transplant recipients. This boost in CMV-specific T cell immunity can potentially reduce the need for antiviral prophylaxis that can impair and delay CMV immune reconstitution.

  2. Safety and Tolerability: Triplex has undergone extensive safety testing, with Phase 1 and Phase 2 studies demonstrating its excellent safety profile and tolerability in over 150 patients and volunteers.

  3. High Immunogenicity: Triplex has been found to be highly immunogenic, meaning it stimulates a strong immune response. This immunogenicity is crucial for effective CMV control and reduction of viral load.

Future Implications and Conclusion

The development of Triplex represents a significant advancement in CMV management for transplant recipients. The ongoing and planned clinical trials will provide valuable insights into the vaccine's effectiveness and its potential to control CMV in various patient populations. If successful, Triplex could revolutionize CMV treatment and reduce the burden of CMV-related complications in transplant recipients.

Helocyte's collaboration with the National Cancer Institute and City of Hope demonstrates the commitment to advancing the field of CMV research and improving patient outcomes. By harnessing the power of Triplex and its ability to enhance CMV-specific T cell immunity, the hope is to minimize the risks associated with CMV reactivation in high-risk transplant recipients.

In conclusion, Triplex holds great promise in the field of CMV management, and ongoing research and clinical trials will shed further light on its efficacy and safety. By leveraging the power of immunotherapy, Helocyte aims to provide a more effective approach to managing CMV events in transplant recipients, ultimately improving patient outcomes and quality of life.

Disclaimer: The information provided in this article is for informational purposes only and should not be considered as medical advice. Please consult with a healthcare professional for personalized recommendations regarding CMV management and treatment options.


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