“Our first finding was kind-of a sanity check,” Dr Villasboas said. To test the platform, the researchers measured the proportions of B cells and T cells surrounding the cancer. They found, as expected, that samples from cHL patients had a higher proportion of T cells compared with noncancerous lymph node and tonsil samples. “We were happy to see our approach was finding things other groups had found with immunohistochemistry or flow cytometry,” said Dr Villasboas.
Having thus verified the technique, the team delved into the variety of markers within the T-cell compartment. One potential goal of analyzing the microenvironment will be to understand what makes cHL uniquely vulnerable to anti–PD-1 therapy, in contrast to even closely related malignancies like non-Hodgkin lymphoma. To this end, they compared the proportion of the different helper T-cell phenotypes among the cHL samples.
Their analysis revealed a high degree of heterogeneity among the cHL patients. “The breakdown between the Th1, Th2, and Th17 phenotypes is very variable,” said Dr Villasboas. In some patients, most of the T cells were Th17, while others had a higher proportion of Th1. They found similar variation in the other T-cell compartments. When they measured the percentage of CD8 cells bearing PD-1, for instance, the 7 healthy controls fell into a fairly tight distribution, while cHL patients ranged from 15% to more than 60%.
“The complexity of the T-cell compartment within these patients with classic Hodgkin lymphoma is very high, and it’s very variable from patient to patient,” said Dr Villasboas. “In the past people have broken this down into individual questions,” he said. ”Our approach is that the immune system is not compartmentalized like that.”
Rather than investigating 1 cell type at a time, mass cytometry allows a rich view into the complex interactions of all these cells. Eventually, correlating the cell-population data with clinical outcomes could yield useful information about disease progression.
“I think there’s both prognostic and therapeutic implications, because you are able to identify populations that you weren’t previously identifying,” said Sanjay Patel, MD, hematopathologist at Weill Cornell Medicine and NewYork-Presbyterian in new York City. “A tool like this is arguably still in the exploratory phase, in terms of the types of data it can yield, but the inherent value in these types of tools is that you can be much more precise about characterizing different subpopulations of cells than ever before.”
- Amir ED, Villasboas JC, McGrath KR, Ansell SM. Immune profiling of the tumor microenvironment in classic Hodgkin lymphoma using high-complexity mass cytometry is feasible and reveals significant multi-compartment heterogeneity between patients. Presented at: the 34th Annual Meeting & Preconference Programs of the Society for Immunotherapy of Cancer (SITC 2019): part 2; November 6–10, 2019; National Harbor, MD. Abstract O43. J Immunother Cancer. 2019;7(283). doi: 10.1186/s40425-019-0764-0
- Cader FZ, Schackmann RCJ, Hu X, et al. Mass cytometry of Hodgkin lymphoma reveals a CD4+ regulatory T-cell-rich and exhausted T-effector microenvironment. Blood. 2018;132(8):825-836. doi: 10.1182/blood-2018-04-843714