One drawback of chemotherapy is poor drug delivery to tumor cells, due in part to hyperpermeability of the tumor vasculature. Extracellular superoxide dismutase (SOD3) is an antioxidant enzyme usually repressed in the tumor milieu. Here we show that specific SOD3 re-expression in tumor-associated endothelial cells (ECs) increases doxorubicin (Doxo) delivery into and chemotherapeutic effect on tumors. Enhanced SOD3 activity fostered perivascular nitric oxide accumulation and reduced vessel leakage by inducing vascular endothelial cadherin (VEC) transcription. SOD3 reduced HIF prolyl hydroxylase domain protein activity, which increased hypoxia-inducible factor-2α (HIF-2α) stability and enhanced its binding to a specific VEC promoter region. EC-specific HIF-2α ablation prevented both the SOD3-mediated increase in VEC transcription and the enhanced Doxo effect. SOD3, VEC, and HIF-2α levels correlated positively in primary colorectal cancers, which suggests a similar interconnection of these proteins in human malignancy.

BackgroundTumor-infiltrating lymphocytes (TILs), mainly CD8+ cytotoxic T lymphocytes (CTL), are linked to immune-mediated control of human cancers and response to immunotherapy. Tumors have nonetheless developed specific mechanisms that selectively restrict T cell entry into the tumor microenvironment. The extracellular superoxide dismutase (SOD3) is an anti-oxidant enzyme usually downregulated in tumors. We hypothesize that upregulation of SOD3 in the tumor microenvironment might be a mechanism to boost T cell infiltration by normalizing the tumor-associated endothelium.ResultsHere we show that SOD3 overexpression in endothelial cells increased in vitro transmigration of naïve and activated CD4+ and CD8+ T cells, but not of myeloid cells. Perivascular expression of SOD3 also specifically increased CD4+ and CD8+ effector T cell infiltration into tumors and improved the effectiveness of adoptively transferred tumor-specific CD8+ T cells. SOD3-induced enhanced transmigration in vitro and tumor infiltration in vivo were not associated to upregulation of T cell chemokines such as CXCL9 or CXCL10, nor to changes in the levels of endothelial adhesion receptors such as intercellular adhesion molecule-1 (ICAM-1) or vascular cell adhesion molecule-1 (VCAM-1). Instead, SOD3 enhanced T cell infiltration via HIF-2α-dependent induction of specific WNT ligands in endothelial cells; this led to WNT signaling pathway activation in the endothelium, FOXM1 stabilization, and transcriptional induction of laminin-α4 (LAMA4), an endothelial basement membrane component permissive for T cell infiltration. In patients with stage II colorectal cancer, SOD3 was associated with increased CD8+ TIL density and disease-free survival. SOD3 expression was also linked to a T cell–inflamed gene signature using the COAD cohort from The Cancer Genome Atlas program.ConclusionOur findings suggest that SOD3-induced upregulation of LAMA4 in endothelial cells boosts selective tumor infiltration by T lymphocytes, thus transforming immunologically “cold” into “hot” tumors. High SOD3 levels are associated with human colon cancer infiltration by CD8+ T cells, with potential consequences for the clinical outcome of these patients. Our results also uncover a cell type–specific, distinct activity of the WNT pathway for the regulation of T cell infiltration into tumors.

Background. There are still few data on the activity and safety of cetuximab-based salvage chemotherapy after immunotherapy (SCAI) in patients with squamous cell cancer of the head and neck (SCCHN). Materials and Methods. Retrospective study of patients with SCCHN who received cetuximab-based SCAI after PD1 or PDL1 (PD(L)1) inhibitors. Overall response rate (ORR) and disease control rate (DCR) with SCAI and with last chemotherapy before immunotherapy (LCBI) by RECIST 1.1, percentage change from baseline in target lesions (PCTL), progression-free survival (PFS), overall survival (OS), treatment compliance and toxicity were evaluated. Results. Between March 2016 and November 2019, 23 patients were identified. SCAI consisted of cetuximabbased combinations (3wkCDDP-5FU-Cetuximab (n=2), wkPaclitaxel-Cetuximab (n=17), wkCDDP-Cetuximab (n=2), wkCBDCA-Paclitaxel-Cetuximab (n=2)). ORR was 56.5% (11 partial response (PR), 2 complete response (CR)). DCR was 78.3%. Among 13 objective responders, median best PCTL was-53.5% (range:-30% to-100%). Median OS and PFS were 12m and 6m, respectively. In 10 patients receiving LCBI, ORR to LCBI was 40%, while ORR to SCAI achieved 60%. In LCBI-treated patients median PFS with LCBI was 8m and median PFS and OS with SCAI were 7m and 12m, respectively. Reduced dose intensity of the chemotherapy and cetuximab components occurred in 82.6% and 52.2% of the patients. Grade 1 or 2 AEs occurred in all patients. Grade 3 or 4 AEs developed in 65%, being grade 3 in all of them except in one patient (grade 4 neutropenia). There were no treatment-related deaths. Conclusion. Cetuximab-based salvage chemotherapy after PD(L)1 inhibitors associated with high response rates and deep tumor reductions with a manageable safety profile. Subsequent lines of therapy may explain the long survival achieved in our series. These results invite to design studies to elucidate the best therapeutic sequence in patients with SCCHN in the immunotherapy era. The Oncologist 2021;9999:• • Implications for Practice: Cetuximab-based salvage chemotherapy (SCAI) achieved high response rates in patients with R/M SCCHN after progression to PD1/PDL1 inhibitors. Objective response rate was higher and progression-free survival was comparable to that of chemotherapy administered before immunotherapy (IO). In most patients, SCAI consisted of weekly, welltolerated regimens. These observations have implications for current practice due to the limited evidence to date in SCCHN and the scant therapeutic options in this disease, and invite to elucidate which may be the best treatment sequence for head and neck cancer patients in the IO era.