Aim 3: Impact of tumor growth on lymphoid tissue organization and function
Early studies have described structural aberrations in murine tumor draining lymph nodes (16) and several studies now describe systemic dysfunction in patient PBMC.
  1. Organization and immune activity of PBMC from cancer patients in hLToC: Potential cancer types being considered are melanoma (high mutation load and immunogenicity, longest clinical experience with checkpoint blockade, potential for successful collaboration) and lymphoma (disruption in lymph node structure are key feature for differential diagnosis). However, any solid tumor could potentially be used, particularly if samples are limiting. With the exception of lymphoma, we will not test other hematological malignancies at this stage as the presence of tumor cells within the PBMC would confound the interpretation of results. Patient PBMC will be obtained via pre-existing clinical collaborations (David Chou, clinical fellow in Ingber lab) and new ones are being initiated with my mentor’s colleagues and my previous colleagues at Dana Farber Cancer Center. We will test 3D organization by imaging and the expression of previously discussed (g) T cell coinhibitory receptors (imaging if reagents and biology permit, else flow cytometry) and stimulation with OKT3 vs OKT3+checkpoint blockade. These experiments could potentially reveal biomarkers for diagnosis as well as response to therapy not evident in patient PBMC.
Tumor interaction with organized immune structures can occur in different ways. Tumors extravasate into lymphatics and establish micrometastases in the lymph node. Tertiary lymphoid tissue can also be seen within solid tumors and plays an active role in tumor growth, immunosuppression and therapeutic responses. Thus, here we explore two different models of tumor-lymphoid tissue interaction
  1. Impact of lymph drainage from a tumor on the organization and activity of the lymph node: a microfluidic model
  2. Encapsulation of lymphoid tissue module in a solid tumor to model tumor associated tertiary lymphoid structures. Depending on feasibility, large number of cells from tumor cell lines or patient specific tumors will be mixed with the lymphocytes to create a 3D representation of tumor stroma with lymphocytes. Lymphocyte organization, polarization and activation will be compared to “healthy” If we are able to obtain matched patient tumor samples, we will grow a solid tumor from the melanoma cells in combination with the hLToC. Several possible combinations are possible but first we will attempt the growth of unfractionated tumor sample (melanoma, immune infiltrate and endothelial cells) in a neighboring channel (can be seeded with <10ul volume, therefore even biopsies can be used) separated from the lymphoid tissue by a lymphatic monolayer. Impact on lymphoid tissue organization, and trafficking of labeled cells from the hLN-on-chip to the cancer can be studied. Further impact on inhibitory receptor and the effect of blocking function on immune stimulation will also be studied as previously discussed. These data will provide a basis for further iteration (tumor fractionation, labeling, chip design) to study melanoma micrometastases in the LN, the difference in response of tumor infiltrating lymphocytes and lymph node lymphocytes to therapy and the construction of a lymph node draining a microfluidcally connected tumor via a lymphatic vessel. In case matched patient samples cannot be obtained other strategies such as HLA typed human cell lines or using hematological malignancies to obtain cancer cells along with PBMC could be considered.