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DFCs for Influenza

Cidara is developing a new generation of immunotherapeutic agents from its Cloudbreak platform that couple potent drugs to a human antibody fragment. These highly potent, long-acting drug-Fc conjugates (DFCs) are designed to inhibit specific disease targets while simultaneously engaging the immune system.




SARS-CoV-2 and
Other Viruses

Influenza (“the flu”) is a contagious viral infection that can cause mild to severe illness, sometimes resulting in death. While today’s flu vaccines are credited with significant public health benefits and offer our current best defense, only 49% of Americans get an annual flu vaccine1, and a majority of those people do not respond. As a result, most Americans are still at risk of getting the flu yearly. In fact, during the 2018-19 flu season, a staggering 71% did not respond to vaccination and 34,200 people died of flu-related illness in the US alone. The estimated average annual total economic burden of influenza to the healthcare system and society is more than $11.2 billion. For more information about influenza, visit the CDC website.

1 Calculated as a weighted average using census data as of July 2019 and flu vaccination coverage data from the US Centers for Disease Control

In the last five years, flu vaccines have only been effective in about 20-50% of people.


Cidara, in collaboration with its global partner Janssen Pharmaceuticals, is developing CD388, a flu DFC, to achieve universal prevention of seasonal and pandemic influenza with a single dose. DFCs are not vaccines or monoclonal antibodies. Their targeting domains are small molecule antivirals that bind to a highly conserved target on the influenza cell surface, which is essential for viral proliferation and enables universal influenza coverage. These long-acting, bispecific DFCs are designed to directly inhibit viral proliferation while simultaneously directing immune-mediated clearance of the virus. The two distinct and complementary mechanisms are designed to maximize antiviral activity of DFCs.

Flu DFCs have the potential to offer significant advantages over current flu vaccines:

  • True universal protection, against all influenza strains and for all people, including those with a compromised immune system
  • Near-immediate protective effects

Cidara and Janssen Therapeutics are currently conducting a Phase 2a clinical trial (NCT05523089) in healthy volunteers with CD388 in its influenza program.


There are currently four drugs recommended by the CDC for treating influenza. All have one or more of the following limitations:

Short half-life and limited efficacy window

Susceptibility to resistance

Multi-dose regimens

Limited routes of administration

Cidara’s flu DFCs for flu treatment are designed to disrupt the current standard of care. The targeting domains of flu DFCs are potent small molecule antivirals that bind to a highly conserved target on the cell surface of all influenza viral strains which is essential for viral proliferation. With this mechanism, DFCs have the potential for fast-acting universal coverage of influenza A and B, including all major clinically characterized drug-resistant strains.

Cidara is conducting IND-enabling studies with CD388 in order to begin Phase 1 clinical trials in its influenza program.