Smart science to improve lives™
TLR4 agonists

Our innovative family of PHAD™ products

PHADs are fully synthetic, highly pure equivalents to bacterial-derived monophosphoryl lipid A (MPLA). They are Toll-like receptor (TLR4) agonists which elicit a strong Th1 immune response. They are highly researched in human clinical studies. We offer three distinct structures in GMP quality for your clinical development.

Benefits of PHAD TLR4 agonists:

  • Enhance immunogenicity: By activating TLR4, PHADs stimulate the immune system to produce a stronger and more robust response to the vaccine antigen. This is crucial for generating lasting immunity.
  • Induce a Th1-type response: Activation of TLR4 tends to skew the immune response towards a Th1-type, which is effective for combating viruses and intracellular bacteria.  

Toll-like receptor (TLR) agonists in vaccines 

Toll-like receptors (TLRs) are a class of proteins that play fundamental roles in innate immunity. They are known as excellent adjuvant targets, having been part of several approved vaccines, such as for cervical cancer, shingles and Hepatitis B. Their discovery was honoured with the 2011 Nobel Prize. By mimicking the structure of pathogens, different compounds acting as TLR agonists can help stimulate the immune system. Find more information like this in our Frequently Asked Questions here.

Click the below links for information on each of our PHAD products:

For more information, explore our frequently asked questions.

PHADs in vaccine development

blue graphic displaying a structural analogue
Synthetic structural analogues of bacterial-derived MPLA with a similar immunological activity
blue graphic of teardrop in hand
Highly pure and GMP manufactured for clinical development
blue graphic of teardrop with plus symbol
Extensively tested in clinical development 
blue graphic of pathogens and antigens
In formulation with various antigens fighting against a range of pathogens and diseases


Versatile and effective, PHAD acts as a TLR4 agonist to activate proinflammatory cytokines and antigen-specific effector cells. PHAD is the first synthetic analogue of monophosphoryl lipid A (MPLA)...



Highly pure, safe, and chemically stable, 3D-PHAD stimulates the immune system through the activation of TLR4, leading to the production of proinflammatory cytokines, CD4+ and CD8+ T-cells. 3D-PHAD is...



Immunostimulatory and highly purified, 3D(6-acyl)-PHAD activates TLR4 to induce proinflammatory cytokines and T-cells. 3D(6-acyl)-PHAD is a synthetically produced structural analogue of monophosphoryl...


Download here:

indicates required field
Please provide your first name
Please provide your last name
E-mail is not valid
We need your consent
Please complete the recaptcha and resubmit the form.

Supporting Literature

Enter your contact details to receive supporting materials.

EXCLUSIVE DOWNLOAD: The PHAD™ range - Highly pure TLR4 agonists

The PHAD™ range Highly pure TLR4 agonists