Recent years have seen a wave of adoptive cell therapies (ACTs), a type of immunotherapy in which T cells (T-cell transfer therapy) and other immune cells are obtained from patients, activated and multiplied outside the body, and instilled in greater numbers back into the circulation. To help fight cancer. In the successful version of ACT known as CAR-T cell therapy, immuno-oncologists additionally genetically engineer a chimeric antigen receptor (CAR) into T cells that binds one of its compartments to a specific type of cancer cell and, together with the other, helps trigger its destructive activity. T-cell cancer cells.
CAR-T cell therapies have advanced into clinical practice to treat tumors of the immune system, such as leukemias and lymphomas, and more recently multiple myeloma, which affects white blood cells in the bone marrow. However, T-cell transfer therapies have not been successfully applied to solid tumors because T cells do not readily penetrate solid tumor masses and persist long enough in them, and because their activity is silenced by an immunosuppressive tumor microenvironment.
One way to overcome these limitations could be to pair T-cell transfer therapies with cytokine therapy. Cytokines are small proteins secreted by certain immune cells that can enhance the tumor-destroying activities of other immune cells, including transduced T cells. However, a serious downside to this approach is the significant side effects resulting from cytokines circulating freely in the body, leading to toxicity and potentially fatal inflammatory syndromes. Additionally, despite the risks that cytokines pose when given on a regular basis, they are often eliminated too quickly to produce the desired therapeutic effects for cancer.
Now, a research collaboration at Harvard’s Wyss Institute for Biologically Inspired Engineering, Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), and Dana-Farber Cancer Institute (DFCI) has developed a nanotechnology-based solution to these problems. The method uses an unnatural sugar that is ingested and incorporated into the outer envelope of T cells, which can then be used to anchor cytokines. Locally concentrated cytokines enhance T-cell functions without unwanted systemic side effects. In mice with melanoma, a type of aggressive solid tumor, this approach also stimulated the host immune system against cancer cells, which inhibited tumor growth. As an addition to CAR-mediated T-cell therapy, it allowed complete regression of lymphomas at non-therapeutic cell doses. The results are published in Proceedings of the National Academy of Sciences(PNAS).
The results we see indicate a major step towards the development of artemisinin-based combination therapies with efficacy against solid tumors and ACTs that act more consistently against a variety of leukemias. Our approach can be easily scaled and integrated with processes currently used to manufacture therapeutic T cells, including CAR-T cells, and thus could have a relatively short path into clinical application. “
David Mooney, Ph.D., senior author, founding core faculty member at the Wyss Institute and Robert P. Pinkas Family Professor of Bioengineering at the Harvard John A. Paulson School of Engineering and Applied Science
Mooney combined her bioengineering expertise with that of cancer immunologist Kai Wucherpfennig, MD, Ph.D. Wucherpfennig is director of the DFCI Center for Cancer Immunotherapy Research, Professor of Neuroscience at Brigham and Harvard Medical School, and Associate Member of the Broad Institute at MIT and Harvard University.
Sugar plus cytokine equals enhanced T-cell therapy
To be able to track cancer reactive dendritic cells, which regulate a broader immune response in lymph nodes, Mooney’s group previously developed a biomaterials-based method that allowed them to attract cells to a 3D scaffold in live animals, where they took a synthetic reactive sugar molecule and used it as a building block for sugar chains. complex on the cell surface.
“In our new study, we similarly harnessed the normal sugar metabolism of cells, but delivered a reactive azido sugar to T cells via nanoparticles in a culture dish. Sugar metabolism in cells utilizes sugar and metabolically incorporates it into complex sugar chains on the cell surface,” said the author. The first is Yutong Liu, a graduate student who works with Mooney. In a second step, using click chemistry, we then exploited the azido group of sugar molecules to bind specific cytokine molecules that had been modified with a highly compatible chemical group. [DBCO] for them. Only having to add sugar-containing nanoparticles and later cytokines to the culture medium makes the method very simple and fully compatible with the adoptive cell fabrication pipeline.”
After optimizing the conjugation process with an array of cytokines in the transplanted T cells, and ensuring that the cells’ viability and general function were not affected, the team tested their approach on mice burdened with solid melanoma tumors. They found that melanoma-specific T cells carrying the anti-tumor cytokine interleukin-12 (IL-12) at non-therapeutic doses significantly delayed the growth of tumors, extending the animals’ lives by 50%. In comparison, the same number of adoptively transferred melanoma-specific T cells combined with systemic injections of IL-12 produced much weaker effects.
Adoptively transferred T cells also have improved viability and differentiation into tumor destroyer cells in animals and include other types of T cells and immune cells that have a role in a broader immune response against tumors. “We saw significantly greater increases in helper T cells and cytotoxic T cells in both dissected tumors and spleens from animals that received IL-12-conjugated melanoma-specific T cells compared to our control conditions, clear signs that these cells have increased tumorigenicity. – said Leo.
The researchers believe that part of the explanation could be that dendritic cells (DCs), which are key regulators of the broader tumour-directed immune response, were more strongly stimulated by melanoma-specific T cells with IL-12 conjugate than by T cells without IL. -12. -12. “We believe our approach can enhance the tumour-specific immune cycle. First, adoptive IL-12-conjugated T cells differentiate and kill a subset of tumor cells, leading to the release of different tumor-specific antigens that are taken up and processed by DCs, which they present to T cells.” Others are tumor-specific in nearby lymph nodes that also invade tumors and directly contribute to the killing of cancer cells and the spread of more antigens,” Liu posited. The effect of antigen diffusion observed by the team may be very relevant to the treatment of solid tumors which often have a very heterogeneous cellular composition and are therefore difficult to attack with targeting only one antigen.
In the final part of their study, the researchers took a T-cell approach to CAR-T cell therapy in a mouse lymphoma xenograft model. Metabolically labeled CAR-T cells with conjugated IL-12 were able to control tumor development and prolong the survival of mice previously injected with lymphoma cells, and at doses at which IL-12-deficient CAR-T cells were not able to treat the animals.
“The straightforward and elegant nature of the new approach to cancer immunotherapy offers huge potential for cancer patients. We are excited to support this effort with the Wyss Institute’s High Priority Validation Project program, which we hope will accelerate its progression into the clinic,” said Wyss founding director Donald Ingber, MD, Ph.D. who is also Yehuda Volkman is Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, W Hansjörg Wyss Professor of Bioengineering in SEAS.
Liu, Y.; et al. (2022) Cytokine conjugation to enhance T cell therapy. PNAS. doi.org/10.1073/pnas.2213222120.