Immunology researchers led by Dartmouth and Dartmouth-Hitchcock’s Norris Cotton Cancer Center discover how the cowpea mosaic plant virus is recognized by and strongly stimulates the immune system to attack and often eliminate cancerous tumors
LEBANON, NH – Previous work by a team of researchers led by Steven N. Fiering, PhD, Immunology and Cancer Immunotherapy researcher at Dartmouth’s and Dartmouth-Hitchcock’s Norris Cotton Cancer Center and Nicole Steinmetz, PhD, Jacobs School of Engineering and Moores Cancer Center, University of California San Diego, showed that a plant virus that does not infect mammals, cowpea mosaic plant virus (CPMV), when injected into cancerous tumors, strongly stimulated the immune system to attack and often eliminate the tumor. However, very little was understood about immune recognition of plant viruses and how and why CPMV is exceptionally immuno-stimulating. In a new study, the team identifies just how CPMV is recognized by the immune system, opening the door for CPMV to be pursued as a new biological drug for treatment of cancer.
CPMV is recognized by the immune system as a pathogen–any infectious agent that can cause disease–through a family of receptors on immune cells called toll-like receptors. Toll-like receptors recognize molecules that signal the invasion of a pathogen and send a warning signal to the immune cells to mobilize to attack the pathogen. When tumors are injected with CPMV, the immune system activates and attacks the tumors by way of this pathogen pattern recognition. “The recognition of CPMV by toll-like receptors illustrates how these receptors are quite flexible and recognize many more molecular patterns than immunologists previously knew,” says Fiering.
During the immune stimulation process, the immune cells release proteins that signal and activate other immune cells, known as cytokines. The team’s study, “Cowpea mosaic virus stimulates antitumor immunity through recognition by multiple MYD88-dependent toll-like receptors,” newly published in Biomaterials, identifies the three toll-like receptors that recognize CPMV. The paper also highlights the importance of a particular cytokine, “interferon alpha,” for strong anti-tumor impact when used as an in situ vaccine to treat cancer.
In situ vaccination, in which tumors are directly treated with immune stimulating reagents, have powerful potential to improve cancer immunotherapy in a safe and inexpensive manner. “In situ vaccination has made contributions already to cancer treatment. CPMV is an excellent reagent that may soon be used to help patients in the same manner,” says Fiering. “The in situ vaccination treatment of a tumor by CPMV can stimulate the immune system to also attack distant metastatic tumors that have not been treated.”
Commercial development of CPMV as a biological drug for the treatment of cancer in the form of in situ vaccination is in progress by Mosaic ImmunoEngineering Inc., a biotech company co-founded by Steinmetz and Fiering with a team of scientists and entrepreneurs. The company has licensed the rights to this technology and is actively pursuing bringing it to the clinic for the direct benefit of patients.
Phase I trials of CPMV in situ vaccination in humans are planned to start in late 2021 or early 2022.
Steven N. Fiering, PhD, is a Professor of Microbiology and Immunology at the Geisel School of Medicine at Dartmouth, and a member of the Immunology and Cancer Immunotherapy Research Program at Dartmouth’s and Dartmouth-Hitchcock’s Norris Cotton Cancer Center. His research interests include developing clinically useful in situ vaccination approaches to generate therapeutic anti-tumor immunity.
About Norris Cotton Cancer Center
Norris Cotton Cancer Center, located on the campus of Dartmouth-Hitchcock Medical Center (DHMC) in Lebanon, NH, combines advanced cancer research at Dartmouth College’s Geisel School of Medicine in Hanover, NH with the highest level of high-quality, innovative, personalized, and compassionate patient-centered cancer care at DHMC, as well as at regional, multi-disciplinary locations and partner hospitals throughout NH and VT. NCCC is one of only 51 centers nationwide to earn the National Cancer Institute’s prestigious “Comprehensive Cancer Center” designation, the result of an outstanding collaboration between DHMC, New Hampshire’s only academic medical center, and Dartmouth College. Now entering its fifth decade, NCCC remains committed to excellence, outreach and education, and strives to prevent and cure cancer, enhance survivorship and to promote cancer health equity through its pioneering interdisciplinary research. Each year the NCCC schedules 61,000 appointments seeing nearly 4,000 newly diagnosed patients, and currently offers its patients more than 100 active clinical trials.
About Dartmouth-Hitchcock Health
Dartmouth-Hitchcock Health (D-HH), New Hampshire’s only academic health system and the state’s largest private employer, serves a population of 1.9 million across northern New England. D-H provides access to more than 2,000 providers in almost every area of medicine, delivering care at its flagship hospital, Dartmouth-Hitchcock Medical Center (DHMC) in Lebanon, NH. DHMC was named again in 2020 as the #1 hospital in New Hampshire by U.S. News & World Report, and recognized for high performance in 9 clinical specialties and procedures. Dartmouth-Hitchcock also includes the Norris Cotton Cancer Center, one of only 51 NCI-designated Comprehensive Cancer Centers in the nation; the Children’s Hospital at Dartmouth-Hitchcock, the state’s only children’s hospital; affiliated member hospitals in Lebanon, Keene, and New London, NH, and Windsor, VT, and Visiting Nurse and Hospice for Vermont and New Hampshire; and 24 Dartmouth-Hitchcock clinics that provide ambulatory services across New Hampshire and Vermont. The D-H system trains nearly 400 residents and fellows annually, and performs world-class research, in partnership with the Geisel School of Medicine at Dartmouth and the White River Junction VA Medical Center in White River Junction, VT.
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