From left: Thomas Marron, MD, PhD; Adeeb Rahman, PhD, Associate Professor, Genetics and Genomic Sciences; and Miriam Merad, MD, PhD

Using a collection of sophisticated single-cell technologies, scientists at the Mount Sinai Health System have launched an early-stage clinical trial that examines the effects of immunotherapy on hepatocellular carcinoma, non-small-cell lung cancer, and head and neck squamous cell carcinoma.

Four to six weeks before a tumor is resected, the researchers administer a neoadjuvant immunotherapy, cemiplimab, and study its effects. As soon as the tumor is removed, they continue to analyze the fresh tissue for a month or more to observe mechanisms of resistance and response. The Phase 1 trial is sponsored by Regeneron Pharmaceuticals, Inc.

“With the technologies available to us at The Tisch Cancer Institute and Mount Sinai’s Human Immune Monitoring Center, we are able to investigate at an unprecedented depth how these immune therapies are changing the microenvironment within the tumor,” says Thomas Marron, MD, PhD, Assistant Professor of Medicine (Hematology and Medical Oncology), Icahn School of Medicine at Mount Sinai, and Principal Investigator of the study. “This trial enables us to analyze fresh tissue immediately after resection—instead of the preserved tissue typically obtained in trials—to observe the dynamic changes that occurred.”

The study is enrolling multiple small cohorts of 21 patients. One goal is to determine which cancer patients will benefit from cemiplimab, and, more specifically, how cemiplimab can be more effective by combining it with chemotherapy and/or other novel immunotherapies. Cemiplimab was previously studied at Mount Sinai in liver and lung cancer patients and has been approved by the U.S. Food and Drug Administration for patients with metastatic cutaneous squamous cell carcinoma. The compound works by inhibiting the interaction between PD-L1, a protein on the surface of tumor cells, and PD-1, the protein on the surface of T cells, and restoring the immune system’s ability to recognize and kill cancer cells.

Another goal of the study is to identify biomarkers in human tissue and blood that will be able to predict who will respond to immunotherapy, since so many patients do not respond to anti-PD-1 therapy. “We really need to find the ideal patients to treat so we don’t unnecessarily expose those who won’t respond to the toxicity of immune therapies,” says Dr. Marron, who is also Assistant Director of Early Phase and Immunotherapy Clinical Trials at Mount Sinai. “There’s also a financial issue at stake for patients and society in general in using expensive drugs that are not improving outcomes.”

Dr. Marron and his team are using several powerful new technologies to help them with their work. These include immune mapping and monitoring technologies such as mass cytometry (CyTOF), a flow-cytometry-like technology that allows them to see up to 50 proteins on each cell so they can identify the cell type and classify the maturation and activation status of the cell, along with some of the regulatory “on/off” checkpoints.

CITE-Seq (Cellular Indexing of Transcriptomes and Epitopes by Sequencing) is another platform that provides an even higher resolution view of each individual cell within the tumor. This technology combines the capabilities of CyTOF and single-cell RNA sequencing to characterize both the RNA and protein in each cell.

A third technology is known as Multiple Ion Beam Imaging (MIBI), a unique form of immunohistochemistry that allows scientists, for the first time, to unravel the spatial architecture of tumors in order to better understand the mechanisms through which the immune system is infiltrating the tumor and is being hijacked by the tumor.

“For 10 years, we’ve been building the Human Immune Monitoring Center into one of the leading platforms in the world for investigating the role of the immune system in human disease, and using that knowledge to design novel, immune-based therapies,” says Miriam Merad, MD, PhD, Director of the Center, and Professor of Oncological Sciences, and Medicine, Icahn School of Medicine at Mount Sinai.

Drawing on a highly specialized team of clinicians, immunologists, mathematicians, physicists, and surgeons, the Human Immune Monitoring Center is currently involved in more than 45 federal- and foundation-funded research programs in fields such as cancer, autoimmune disease, inflammatory bowel disease, allergies, and neurodegenerative disease.

A PET-CT scan indicates one patient’s partial response to the in situ vaccination after six months. as shown in pre-vaccine, left, and six months post-vaccine.

Researchers at the Icahn School of Medicine at Mount Sinai are pioneering two novel approaches to cancer immunotherapy that are promising for patients with non-Hodgkin lymphoma and other solid tumors, which have been stubbornly resistant to therapies such as checkpoint blockade.

One new approach is an in situ vaccination that worked so well in patients with advanced-stage lymphoma that it is now undergoing trials for breast cancer, as well as head and neck cancers. The other therapy captures the synergy of checkpoint blockade and stem cell transplantation in the form of a highly promising treatment known as immunotransplant. Joshua Brody, MD, Director of the Lymphoma Immunotherapy Program and Assistant Professor of Medicine (Hematology and Medical Oncology) at The Tisch Cancer Institute at Mount Sinai, is the lead investigator for both therapies.

The In Situ Vaccination

This vaccination approach involves injecting immune stimulants directly into a single tumor site, which “teaches” the immune system to recognize and destroy cancer cells at that site and throughout the body. “We’re teaching dendritic cells—the generals of the immune system army—to specifically recognize tumor antigens, which then instruct the T cells, the immune system’s soldiers, to go forth and kill the cancer cells while sparing non-cancer cells,” says Dr. Brody.

As reported in the April 2019 issue of Nature Medicine, this therapy involves several steps that begin with injection of a small molecule that calls the dendritic cells to action, followed by low-dose radiation to kill the tumor cells. These dying cells, in turn, release antigens into the immune system that are recognized by the dendritic cells and presented to the T cells as part of the “coaching” process.

The results were encouraging among a cohort of 11 patients with non-Hodgkin lymphoma. In earlier tests with lab mice, the vaccine was able to cure about 40 percent of lymphoma tumors, Dr. Brody says. When combined with checkpoint blockade, the cure rate nearly doubled. Dr. Brody reports that when testing the therapy in patients, “We saw some who had profound regressions of their entire tumor burden. After treating one site, tumors throughout the body melted away.”

The next step in the development of the vaccine began last spring when Mount Sinai began recruiting patients for a clinical trial that combines the vaccine therapy with checkpoint blockade—a widely used treatment that effectively removes the brakes from T cells so they are free to attack cancer cells. This trial will target lymphomas, as well as breast cancer and head and neck cancers.

Immunotransplant Therapy

While PD-1 blockade has been effective for some lymphoma patients, its ability to help those with non-Hodgkin lymphoma has been more challenging. Even anti-PD-1/anti-CTLA4 dual checkpoint blockade has yielded limited efficacy, perhaps due to insufficient T cell activation.

Recently, Dr. Brody and his team found that combining immunotherapy and stem cell transplantation may be beneficial. In this first-of-its-kind approach, reported in Cancer Discovery, the researchers were able to increase the cancer-killing immune response tenfold when tested in the lab, making it effective against not just non-Hodgkin lymphoma but also melanoma and lung cancer.

“In the lab, immunotransplant either prolonged survival greatly compared to immunotherapy alone or actually cured a significant portion of mice with melanoma and lung cancer,” Dr. Brody says.

Immunotransplant works through the principle of homeostatic proliferation: when T cells are put into an empty organism or body, they become activated and begin to wildly multiply. In immunotransplant, T cells are withdrawn from the blood through apheresis, clearing the way for their reintroduction as infused immune cells. As they proliferate, these reinvigorated T cells build the immune system back up, become activated, and enable checkpoint blockade to achieve its full cancer-fighting potential.

The fact that checkpoint blockade has become the standard of care for treating melanoma, kidney cancer, lung cancer, and other diseases underscores the promise of immunotransplant. “We’ve shown we can increase the power of checkpoint blockade immunotherapy to prolong survival and induce cures in aggressive cancers, and that means not just lymphomas but solid tumor types,” says Dr. Brody.