Immunotherapy converts nonimmunogenic pancreatic tumors into immunogenic foci of immune regulation

ER Lutz, AA Wu, E Bigelow, R Sharma, G Mo… - Cancer immunology …, 2014 - AACR
ER Lutz, AA Wu, E Bigelow, R Sharma, G Mo, K Soares, S Solt, A Dorman, A Wamwea…
Cancer immunology research, 2014AACR
Pancreatic ductal adenocarcinoma (PDAC) is considered a “nonimmunogenic” neoplasm.
Single-agent immunotherapies have failed to demonstrate significant clinical activity in
PDAC and other “nonimmunogenic” tumors, in part due to a complex tumor
microenvironment (TME) that provides a formidable barrier to immune infiltration and
function. We designed a neoadjuvant and adjuvant clinical trial comparing an irradiated,
granulocyte-macrophage colony-stimulating factor (GM-CSF)–secreting, allogeneic PDAC …
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is considered a “nonimmunogenic” neoplasm. Single-agent immunotherapies have failed to demonstrate significant clinical activity in PDAC and other “nonimmunogenic” tumors, in part due to a complex tumor microenvironment (TME) that provides a formidable barrier to immune infiltration and function. We designed a neoadjuvant and adjuvant clinical trial comparing an irradiated, granulocyte-macrophage colony-stimulating factor (GM-CSF)–secreting, allogeneic PDAC vaccine (GVAX) given as a single agent or in combination with low-dose cyclophosphamide to deplete regulatory T cells (Treg) as a means to study how the TME is altered by immunotherapy. Examination of resected PDACs revealed the formation of vaccine-induced intratumoral tertiary lymphoid aggregates in 33 of 39 patients 2 weeks after vaccine treatment. Immunohistochemical analysis showed these aggregates to be regulatory structures of adaptive immunity. Microarray analysis of microdissected aggregates identified gene-expression signatures in five signaling pathways involved in regulating immune-cell activation and trafficking that were associated with improved postvaccination responses. A suppressed Treg pathway and an enhanced Th17 pathway within these aggregates were associated with improved survival, enhanced postvaccination mesothelin-specific T-cell responses, and increased intratumoral Teff:Treg ratios. This study provides the first example of immune-based therapy converting a “nonimmunogenic” neoplasm into an “immunogenic” neoplasm by inducing infiltration of T cells and development of tertiary lymphoid structures in the TME. Post-GVAX T-cell infiltration and aggregate formation resulted in the upregulation of immunosuppressive regulatory mechanisms, including the PD-1–PD-L1 pathway, suggesting that patients with vaccine-primed PDAC may be better candidates than vaccine-naïve patients for immune checkpoint and other immunomodulatory therapies. Cancer Immunol Res; 2(7); 616–31. ©2014 AACR.
AACR