Beyond Antivirals: New Hope to Disarm a Common Transplant Threat

TORONTO, ON – May 28, 2026 – By Christine Carter

A first-in-human clinical trial has begun for an innovative therapy that treats donor kidneys outside the body, marking a potential paradigm shift in preventing a common and dangerous viral complication that affects thousands of organ transplant recipients each year. Danish biotechnology company Synklino A/S announced that the first patient has been dosed with SYN002, a drug designed to neutralize a latent virus directly within the donor organ before it is transplanted.

The Phase 1 study, conducted at the world-renowned Ajmera Transplant Centre in Toronto, represents a significant step toward addressing a critical unmet need in transplant medicine. If successful, the approach could spare vulnerable patients from the debilitating effects of viral reactivation and the toxicities of long-term antiviral medications.

The Persistent Challenge of CMV

For kidney transplant recipients, the gift of a new organ is often shadowed by the threat of cytomegalovirus, or CMV. This common herpesvirus is dormant in an estimated 60–70% of the population and, consequently, in a majority of donor organs. While harmless for most healthy individuals, the virus poses a significant risk to transplant patients, whose immune systems are intentionally suppressed to prevent organ rejection.

Under these conditions, the latent virus can reactivate, leading to CMV viremia—the presence of the virus in the bloodstream. Current standard-of-care relies on months of prophylactic antiviral drugs like valganciclovir. Despite this, CMV reactivation still occurs in approximately 30% of recipients of CMV-positive organs, leading to a cascade of potential problems including fever, organ damage, increased risk of graft rejection, rehospitalization, and even death.

“Despite the advances in antiviral prophylaxis for the prevention of CMV disease after kidney transplantation, we still see patients who become viremic after their transplant and some of them develop overt CMV disease,” said Professor Atul Humar, the study's principal investigator. Humar is an internationally recognized expert in transplant infectious diseases at the University Health Network (UHN) in Toronto.

A major limitation of current drugs is that they only target the virus during its active, or lytic, phase. They cannot eliminate the dormant, or latent, viral reservoir hiding within the cells of the donor organ. Furthermore, these systemic antiviral drugs are not without their own risks, frequently causing side effects like bone marrow suppression, which can lead to dangerously low white blood cell counts and increase the risk of other infections.

A Paradigm Shift: Treating the Organ, Not the Patient

Synklino's SYN002 aims to circumvent these challenges with a radically different strategy: eliminating the virus at its source. Instead of treating the patient with systemic drugs after the transplant, SYN002 is administered directly to the donor kidney before transplantation using a technique called normothermic machine perfusion (NMP).

During NMP, the organ is placed in a device that pumps warm, oxygenated, nutrient-rich fluid through it, keeping it in a near-physiological state outside the body. This preservation window provides a unique opportunity to deliver therapy. SYN002 is added to the perfusion fluid, where it seeks out and destroys cells infected with CMV.

Its mechanism is highly specific. The drug is an immunotoxin designed to bind to a protein called US28, a receptor found exclusively on the surface of both latently and actively CMV-infected cells. Once bound, the drug is internalized by the cell, triggering its programmed death and thereby destroying the viral reservoir. Because the treatment is confined to the organ ex vivo, the transplant recipient is not exposed to the drug, avoiding the potential for systemic side effects.

“Initiating this Phase 1 study allows us to begin evaluating whether those findings translate into transplant patients,” said Ian McGowan, MD PhD, Chief Medical Officer at Synklino. “This represents a key milestone in the development of SYN002 for CMV prevention and our broader goal of improving transplant outcomes for patients who remain at risk despite current standard-of-care prophylaxis.”

From Lab to Clinic: The Path to Human Trials

The initiation of the human trial builds on compelling preclinical evidence. A foundational study, conducted in collaboration with the University of Cambridge and published in the prestigious American Journal of Transplantation, demonstrated that treating human donor kidneys with SYN002 during ex vivo perfusion resulted in a greater than 90% reduction in CMV reactivation from latency. This provided the crucial proof-of-concept needed to advance into the clinic.

The current Phase 1 trial is a dose-escalation study designed primarily to assess the safety and tolerability of SYN002. The trial will enroll four cohorts of patients receiving CMV-positive donor kidneys at the Ajmera Transplant Centre, home to Canada's largest transplant program. As a secondary goal, researchers will monitor patients for six months post-transplant to gather preliminary data on whether the treatment reduces the rate of viral reactivation compared to historical data.

Professor Humar noted the novelty of the approach. “SYN002 represents a novel approach to CMV prevention in this patient population, and the start of dosing is an important step forward as we begin to evaluate SYN002 in the clinic,” he commented.

Initial safety findings from the first cohort of patients are anticipated in the second half of 2026, with a final readout of the complete study expected in 2027. The involvement of Professor Humar and the world-class Ajmera Transplant Centre lends significant credibility and expertise to the trial, underscoring the potential importance of this new therapeutic strategy.

Navigating the High-Stakes Transplant Market

For Synklino, a clinical-stage biotechnology company, the start of its first human trial is a pivotal moment that could validate its entire platform. Successfully targeting the latent CMV reservoir would place SYN002 in a class of its own, addressing a clear deficiency in the current treatment paradigm. While recent advances like the approval of letermovir have provided safer systemic options for some transplant populations, they do not offer an ex vivo solution that eradicates the virus from the donor organ.

Other long-term strategies, such as the development of CMV vaccines, are also underway at various companies but remain years from potential implementation and serve a different purpose of preventing initial infection rather than managing a pre-existing viral load in a donor organ. Synklino’s ex vivo approach is unique in its focus and timing, positioning it as a complementary or even superior preventative measure specifically for the transplant setting.

The path forward involves navigating a complex regulatory landscape for what is considered an advanced therapy. However, by targeting a serious condition with a clear unmet need, SYN002 could be eligible for expedited regulatory pathways. If the Phase 1 trial confirms the therapy's safety and shows promising signs of efficacy, it would not only be a significant win for patients but also a major de-risking event for the company, potentially attracting further investment and partnerships to fund the larger trials required for approval.