When we think of viruses, we often think of diseases, pandemics and death. Our impression of viruses is that they are “bad”. But viruses could also be a possible cure for the deadliest disease in modern history: cancer. The therapeutic effects of “good” cancer-killing oncolytic viruses have been documented over a century ago. Records from as early as 1904 described a 42-year old woman with acute leukemia who experienced temporary remission after an influenza infection. Other early reports showed spontaneous remission of Hodgkin lymphoma and Burkitt’s lymphoma after natural infections with the measles virus.

Despite the long history, oncolytic viruses have only recently gained momentum in the scientific community. Dr. Aldo Pourchet, CSO and co-founder of Omios Biologics—a biotech startup in the San Francisco Bay area—is determined to harness the power of oncolytic viruses to develop a new generation of cancer immunotherapy.

How Oncolytic Viruses Work

“One thing that we know for sure is that you need the immune system to fight the cancer,” says Pourchet. “You need to recruit the immune system, and probably the best thing we know for recruiting the immune system is viruses. Our immune system evolved to detect them immediately. That’s why we are still on Earth. It’s because we have been able to fight deadly viruses.”

In 2020, Promega North America launched the Diversification Of Our Research Scientists (DOORS) Scholarship to recognize and empower students from underrepresented backgrounds. Ten students received $5,000 towards tuition and other costs associated with their education, as well as connections with mentors from Promega. Here are two of their stories.

Immune checkpoint inhibitor (ICI), or immune checkpoint blockade, therapies are a revolutionary, and relatively new, approach to treating cancer. These therapies work by blocking immune checkpoint proteins that act to negatively regulate the immune system through the PD-1 pathway. Some tumors express immune checkpoints to prevent the immune system from producing a strong enough immune response to kill the cancer cells. When these checkpoint proteins are blocked by an ICI, the body’s T-cells can recognize and kill the cancer cells. ICI therapies show tremendous promise. Unfortunately, not all tumors express immune checkpoint proteins, and so, not all tumors will be effectively treated with ICI therapies. The challenge is differentiating between the tumors that will respond and tumors that won’t.

DNA Mismatch Repair Deficiency Status as Detected by Microsatellite Instability or Immunohisotchemistry are Important Biomarkers for ICI

Biomarkers are measurable indicators of a clinical condition that can be found in tissue, blood, or other fluids. Predictive biomarkers for ICIs can help determine if these therapies are a suitable choice for treatment. Some tumors have deficiencies in their DNA mismatch repair mechanisms. Mismatch repair deficiency (dMMR) leads to the accumulation of mutations across the genome, particularly in microsatellites, which over time can result in higher levels of neoantigen production, rendering the tumors susceptible to the ICI therapy (1–5).

In 2017, Le et al. demonstrated that dMMR status reliably predicted response to an ICI therapy targeting the PD-1 checkpoint protein (6). Following this discovery, ICI based on dMMR  determined using either microsatellite instbility (MSI) or immunohistochemistry (IHC), gained clearance from the US Food and Drug Administation (FDA) for microsatellite instability-high (MSI-H) or dMMR by IHC solid tumors. This was the first time a cancer treatment was cleared based on a biomarker regardless of cancer origin (1,7).  Since then, MSI-H and dMMR, have become some of the most recognized tissue agnostic biomarkers for improved survival following ICI therapy of solid tumors (6,8,9).

A tiny worm called Onchocerca lupi can make life uncomfortable for both humans and their best friends. This thread-like nematode is found in the eyes or under the skin of infected animals. Historically, diagnosis required skin biopsy or surgical removal of ocular tissue, but a recent study demonstrates a new non-invasive diagnostic tool for infection by Onchocerca lupi in dogs.