Glutamine is essential for overcoming the immunosuppressive microenvironment in malignant salivary gland tumors.

Rationale: Immunosuppression in the tumor microenvironment (TME) is key to the pathogenesis of solid tumors. Tumor cell-intrinsic autophagy is critical for sustaining both tumor cell metabolism and survival. However, the role of autophagy in the host immune system that allows cancer cells to escape immune destruction remains poorly understood. Here, we determined if attenuated host autophagy is sufficient to induce tumor rejection through reinforced adaptive immunity. Furthermore, we determined whether dietary glutamine supplementation, mimicking attenuated host autophagy, is capable of promoting antitumor immunity. Methods: A syngeneic orthotopic tumor model in Atg5+/+ and Atg5flox/flox mice was established to determine the impact of host autophagy on the antitumor effects against mouse malignant salivary gland tumors (MSTs). Multiple cohorts of immunocompetent mice were used for oncoimmunology studies, including inflammatory cytokine levels, macrophage, CD4+, and CD8+ cells tumor infiltration at 14 days and 28 days after MST inoculation. In vitro differentiation and in vivo dietary glutamine supplementation were used to assess the effects of glutamine on Treg differentiation and tumor expansion. Results: We showed that mice deficient in the essential autophagy gene, Atg5, rejected orthotopic allografts of isogenic MST cells. An enhanced antitumor immune response evidenced by reduction of both M1 and M2 macrophages, increased infiltration of CD8+ T cells, elevated IFN-γ production, as well as decreased inhibitory Tregs within TME and spleens of tumor-bearing Atg5flox/flox mice. Mechanistically, ATG5 deficiency increased glutamine level in tumors. We further demonstrated that dietary glutamine supplementation partially increased glutamine levels and restored potent antitumor responses in Atg5+/+ mice. Conclusions: Dietary glutamine supplementation exposes a previously undefined difference in plasticity between cancer cells, cytotoxic CD8+ T cells and Tregs.

Readmission and complications after robotic surgery: experience of 10,000 operations at a comprehensive cancer center.

Evaluation of safety is of paramount importance with adoption of novel surgical technology. Although robotic surgery has become widely used in oncologic surgery, analysis of safety is lacking in comparison to traditional techniques. Standardized assessment of robotic surgical outcomes and adverse events following oncologic surgery is necessary for quality improvement with innovative technology. Between 2003 and 2016, 10,013 unique robotic operations were performed in 9,858 patients. Our prospectively maintained database was retrospectively reviewed for hospital readmissions and Clavien-Dindo grade ≥ 2 complications within 30 days. Multivariable logistic regression was used to identify predictors of surgical complications and hospital readmissions. Cases were stratified by discipline: genitourinary (n = 8240), gynecologic (n = 857), thoracic (n = 457), gastrointestinal (n = 322), hepatobiliary (n = 60), ear/nose/throat (n = 44) and general (n = 33). Intraoperative complications occurred in 42 surgeries (0.4%). Postoperative complications occurred in 946 patients [9.4%, highest grade 2 (n = 574), 3 (n = 288), 4 (n = 72), 5 (n = 10)]. Most frequent complications were ileus (154, 16.3%), anemia (91, 9.6%), cardiac arrhythmia (62, 6.6%), deep vein thrombosis/pulmonary embolus (47, 5.0%), wound infection (45, 4.8%) and urinary leak (43, 4.5%). 405 patients (4.0%) required readmission. Most common causes for hospital readmission were ileus (44, 10.9%), urinary leak (23, 5.7%), urinary tract infection (23, 5.7%), intra-abdominal abscess/fluid collection (23, 5.7%), and small bowel obstruction (19, 4.7%). On multivariable analysis, longer operative time and older age predicted complications and readmissions (p ≤ 0.02). Robotic-assisted surgery appears a safe for oncologic surgery with acceptable hospital readmission and complication rates. Older age and longer operative time were associated with complications and readmission.