How MDNA55 works
MDNA55 aims to deliver a toxin specifically to the tumor cells, resulting in their death and a reduction in tumor size. It takes advantage of an existing system within the body to minimize the chance that the toxin is delivered to healthy tissues.
MDNA55 is a fusion protein, consisting of a modified interleukin-4 (IL-4) protein linked to a modified toxin from the bacteria Pseudomonas. IL-4 binds to a receptor protein called IL-4R, which is normally found only on certain immune cells. This binding triggers a process where the bound IL-4/IL-R4 proteins are both taken inside the cell and initiate a signaling pathway to promote the growth or activation of immune cells.
IL-4R also is commonly over-produced by several cancer types and especially in glioblastoma, a type of brain cancer. This means that using the specific IL-4/IL-R4 interaction to deliver a toxin should minimize the damage it can cause to other tissues. The Pseudomonas toxin is harmless outside cells, but when internalized by the tumor cells following IL-4 binding to IL-R4, it can inhibit protein production and cause the cells to die.
In order to access a brain tumor, a drug must pass through the blood-brain barrier (BBB), which is impermeable to most substances. To get around this, Medicenna uses a technique called convection-enhanced delivery (CED), which involves implanting narrow catheters (tubes) directly into the brain near the site of the tumor.
MDNA55 in clinical trials
Medicenna is currently investigating MDNA55 in an open-label, Phase 2 clinical trial (NCT02858895) in patients with glioblastoma that has returned or progressed while on another therapy. The trial, which is still enrolling participants, aims to recruit 43 patients at multiple sites across the U.S.
MDNA55 will be administered directly to the tumor through CED as a single dose. Patients will be monitored for up to 360 days following treatment. The trial will assess how effective the delivery of MDNA55 to the tumor is, any anti-tumor activity, and any adverse effects as a result of the treatment.
A planned interim safety analysis showed that MDNA55 delivery appears to be effective covering between 43 to 100 percent of the tumor in the first 10 patients analyzed. Furthermore, MDNA55 appears to be safe, with no severe adverse events related to the treatment being reported.
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