There has been a lot of attention surrounding the effectiveness of PD-1 drugs lately. The New York Times published an article recently on how such drugs are “unleashing the immune system to attack cancer cells…” and that this “could be an alternative to often-debilitating chemotherapy.”
First, let’s discuss what PD-1 is and it’s role in immunotherapy. PD-1 stands for Programmed Death. It is a protein found on the surface of T-cells (immune system cells) in our bodies; this protein binds with protein PD-L1 that is expressed in cancer cells, and together they protect the cancer cell from attack by our own immune system.
One patient blog simplifies how PD-1 works, in this analogy:
“Basically, we have an intruder in the midst and a turncoat in our army of immune cells that enables him to remain hidden. Anti-PD-1 is an immunotherapy drug that targets breaking that PD-1/PD-L1 shield so the loyal soldiers can get in there and give these tumor cells a good old-fashioned beating. The antibody primarily prevents the binding of the PD-1 and PD-L1 proteins; generally speaking, it keeps that connection from happening and thus enables the T cells to do their job and unleash hell on the cancer cells. Turncoat thwarted, enemy defeated.”
Research findings have shown that the newer PD-1 drugs appears to be well tolerated and, while not clearly established, there are hints that the drugs will enable people to live longer.
Researchers are continuing to study the new drugs and investigate if they can improve their results by combining them with other therapies. This is the vision OncoSec had in mind when entering into a sponsored research agreement with Old Dominion University and the Frank Reidy Research Center for Bioelectrics to initiate a combination study using our ImmunoPulse technology alongside anti-CTLA4, anti-PD1 and anti-PDL-1 therapies.
As patients can have resistances to certain treatment types and a monotherapy may not always result in a complete response, a combination approach can potentially address some of these issues.
With our combination study, we see an opportunity to increase response rates and overall effectiveness. The specific drugs used in these polytherapy approaches are especially useful in negating defensive measures that cancer cells have, such as using PD-1 to confuse immune cells – a factor that makes them much more difficult to locate and, in turn, lowers response rates to treatment.
On October 8th, we announced the first preliminary safety data from the study. Results have shown to be encouraging.
As the first experiment for our combination approach, this round used a melanoma mouse model (forty mice in eight treatment groups with single tumors), to test for safety in combining these potential treatment methods. Each mouse was treated with either ImmunoPulse alone or in combination with anti-CTLA4, anti-PD1 or a combination of all three, at varying levels of concentration. With our goal of achieving a high safety profile through our immunotherapy approach, it was encouraging to see that no mice died from toxicity from the treatments.
Turning to treatment effectiveness, the preliminary data showed 100% of treated lesions demonstrating complete regression. These preliminary results are encouraging, and can be a signal that a combination of ImmunoPulse with anti-PD1 and/or anti-CTLA4 has the potential to be both safe and effective. OncoSec and our research partners will continue to explore the possibilities of combination treatments.
We will continue to update shareholders, the scientific community and the general public as to our progress, when more data becomes available. For company updates from OncoSec, please join our newsletter. To join our online community and learn more about treatment methods, risk factors, prevention and cancer survivors, please see our Facebook and Twitter pages.
(Main image by e-Magine Art)