Product Spotlight: PHAD® Adjuvants

Posted on November 16, 2021

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November is almost over, and vaccine month 2021 is coming to an end. So, it’s time for a recap of what we’ve been saying all month – Avanti has you covered when it comes to lipid-based adjuvants. As you’ve seen in our research spotlights, our PHAD® adjuvants can be used individually or in combination with other adjuvants to elicit stronger immune responses when compared to vaccines relying on an antigen alone. Regardless of which type of adjuvant(s) you choose for your vaccine research, you can rest assured that when you choose Avanti and Croda, you’re choosing safe and effective adjuvants. Let’s take a quick look at some of our lipid-based adjuvant products in the PHAD® line.

The PHAD® lipid-based adjuvant product line

PHAD® is a synthetic structural analog of monophosphoryl Lipid A (MPLA) that has been shown to boost the immune system through activation of the toll-like receptor 4 (TLR4) resulting in production of proinflammatory cytokines and antigen-specific effector CD4+ and memory CD8+ T cells. Also referred to as GLA, this adjuvant has been administered to well over 1000 human subjects without serious adverse events. PHAD® is available in bulk quantities for vaccine development and commercial manufacturing.

PHAD®-504 was designed as a synthetic structural analog of detoxified MPLA derived from E. coli lipopolysaccharide (LPS). It is structurally similar to PHAD®, differing only in the length of a single fatty acid chain. As expected, the activity of PHAD®-504 is quite similar to that of PHAD®, making the two products interchangeable as adjuvants in vaccine or immunotherapy formulations.

The highly pure MPLA analog, 3D-PHAD®, provides a homogeneous synthetic equivalent for the 3-deacylated MPLA derived from bacterial LPS. While comparable to bacterial MPLA and other synthetic MPLA analogs at eliciting an immune response in a liposomal adjuvant system (see bar graph), 3D-PHAD® is less pyrogenic than its bacterial-derived mimic.

The MPLA structural analog, 3D(6-acyl)-PHAD®, is the synthetic MPLA most closely related to the reported structure of MPL® Adjuvant used in GSK’s Adjuvant Systems AS01, AS02, and AS04. As with other synthetic MPLA analogs manufactured by Avanti, it is structurally homogeneous and highly purified, and mimics the TLR4 agonist activity of bacterial MPLA.

How well do these synthetic adjuvants work compared to the natural version?

The graph below shows the stimulatory effect of PHAD®, 3D-PHAD®, and 3D(6-acyl)-PHAD® on macrophages. Macrophage cell line J774 cells were cultured with Avanti PHAD®, 3D-PHAD®, or 3D(6-acyl)-PHAD® for 24hrs. IL-12 levels in supernatants were measured by sandwich ELISA.

Check out how these adjuvants are being used!

We’ve been highlighting a lot of recent research in our research spotlights this month but that was just the tip of the iceberg. Check out the list below for more articles that feature Avanti’s PHAD product line!