Abstract P2-09-14: Immunogenomic pathway and survival analysis in breast cancers based on tumor location and molecular subtypes

Introduction: Most breast tumors respond poorly to immunotherapy. Triple-negative breast cancer (TNBC) breast tumors are thought to be more immunogenic than other breast cancer subtypes (luminal A/B or HER2+). Increased immune response in TNBC are characterized by high levels of tumor infiltrating T lymphocyte (TIL) composition that would predict excellent response to immune checkpoint blockade. For all breast cancers, tumors appear more commonly in the upper outer quadrant. However, it is not clear whether expression of immune response genes vary with tumor location among the subtypes. Here, we hypothesized that by analyzing differential gene expression associated with immune response pathways among molecular subtypes of breast cancer such as luminal A/B, HER2+ or TNBC, we can identify targetable pathways to improve therapy with breast cancer.

Methods: Using the Cancer Genome Atlas (TCGA) dataset, we have identified 918 breast cancer tumor samples and compared RNAseq gene expression based on molecular subtypes and anatomic locations of biopsies (i.e., right, left, lower inner quadrant, lower outer quadrant, upper inner quadrant or upper outer quadrant). Genes with significantly different expression (p<0.01) were selected for survival analysis. R, Reactome Pathway Browser were used to retrieve and analyze data.

Results: In TNBC, tumors from lower outer quadrant, lower inner quadrant demonstrated significantly higher CD8B mRNA expression compared with luminalA/B and HER2 (p=2.93E-04, 2.73E-04) from same locations. CD8B mRNA was not significantly higher in TNBC tumors of other sites compared with luminalA/B and HER2. However, pathway/genes associated with CTL function remained significantly different between the different sites for TNBC compared with other subtypes. The metastasis suppressor gene, CD82, was significantly higher in TNBC samples from the right side (p=4.83E-05), lower outer quadrant (p=4.33E-05), lower inner quadrant (p=3.32E-03) and upper inner quadrant (p=4.51E-07), but this gene was not significantly expressed in the upper outer region, where tumors are prevalent.

From immune pathway analysis, genes involved in the antigen activates B cell receptor pathway (p<0.05) were associated with overall survival (OS) in right and left sided Luminal A/B and HER2 tumors and right sided TNBC tumors. Finally, genes from pathway involved in immune-regulatory interactions between a lymphoid and a non-lymphoid cells were associated with OS in lower outer quadrant, upper outer quadrant tumors in luminal A/B and HER2 cases and right sided tumors in TNBC (p<0.05).

Conclusion: While previous studies have reported that tumor infiltrating lymphocytes and lymphoid aggregates in tumors are associated with survival, following more complex analysis, we reveal novel genes and immune pathways that demonstrate improved survival prediction in the TCGA dataset for breast cancers. Furthermore, as expected, we confirm that different immune pathways are associated with survival in luminalA/B, HER2 and TNBC tumors. Our findings demonstrate the importance of a patient-centered approach to the treatment of patients with breast cancer.

Citation Format: Shen Y, Shyu C-R, Mitchem JB, Ding F, Shajahan-Haq AN. Immunogenomic pathway and survival analysis in breast cancers based on tumor location and molecular subtypes [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-14.

What is the optimal management of an intra-operative air leak in a colorectal anastomosis?

AIM

An airtight anastomosis on intra-operative leak testing has been previously demonstrated to be associated with a lower risk of clinically significant postoperative anastomotic leak following left-sided colorectal anastomosis. However, to date, there is no consistently agreed upon method for management of an intra-operative anastomotic leak. Therefore, we powered a noninferiority study to determine whether suture repair alone was an appropriate strategy for the management of an intra-operative air leak.

METHOD

This is a retrospective cohort analysis of prospectively collected data from a tertiary care referral centre. We included all consecutive patients with left-sided colorectal or ileorectal anastomoses and evidence of air leak during intra-operative leak testing. Patients were excluded if proximal diversion was planned preoperatively, a pre-existing proximal diversion was present at the time of surgery or an anastomosis was ultimately unable to be completed. The primary outcome measure was clinically significant anastomotic leak, as defined by the Surgical Infection Study Group at 30 days.

RESULTS

From a sample of 2360 patients, 119 had an intra-operative air leak during leak testing. Sixty-eight patients underwent suture repair alone and 51 underwent proximal diversion or anastomotic reconstruction. The clinically significant leak rate was 9% (6/68; 95% CI: 2-15%) in the suture repair alone arm and 0% (0/51) in the diversion or reconstruction arm.

CONCLUSION

Suture repair alone does not meet the criteria for noninferiority for the management of intra-operative air leak during left-sided colorectal anastomosis. Further repair of intra-operative air leak by suture repair alone should be reconsidered given these findings.

Myeloid-derived suppressor cells: general characteristics and relevance to clinical management of pancreatic cancer

Recent studies describe a heterogeneous population of cells of the myeloid lineage, termed myeloid derived suppressor cells (MDSC), which are observed with increased prevalence in the peripheral blood and tumor microenvironment of cancer patients, including pancreatic cancer. Accumulation of MDSC in the peripheral circulation has been related to extent of disease, and correlates with stage. MDSC have primarily been implicated in promoting tumor growth by suppressing antitumor immunity. There is also compelling evidence MDSC are also involved in angiogenesis and metastatic spread. Two main subsets of MDSC have been identified in cancer patients: a monocytic subset, characterized by expression of CD14, and a granulocytic subset characterized by expression of CD15. Both subsets of MDSC actively suppress host immunity through a variety of mechanisms including production of reactive oxygen species and arginase. Just as in humans, accumulation of monocytic and granulocytic MDSC has been noted in the bone marrow, spleen, peripheral circulation, and tumors of tumor bearing mice. Successful targeting of MDSC in mice is associated with improved immune responses, delayed tumor growth, improved survival, and increased efficacy of vaccine therapy. By further elucidating mechanisms of MDSC recruitment and maintenance in the tumor environment, strategies could be developed to reverse immune tolerance to tumor. We discuss here what is currently known about MDSC as well as some potential strategies targeting MDSC in the context of our work on pancreatic cancer and recent literature. Due to the number of new reports on MDSC, the most pertinent ones have been selected.