Purpose: Molecular classification of breast cancer has been proposed based on gene expression profiles of human tumors. Luminal, basal-like, normal-like, and erbB2+ subgroups were identified and were shown to have different prognoses. The goal of this research was to determine if these different molecular subtypes of breast cancer also respond differently to preoperative chemotherapy. Experimental Design: Fine needle aspirations of 82 breast cancers were obtained before starting preoperative paclitaxel followed by 5-fluorouracil, doxorubicin, and cyclophosphamide chemotherapy. Gene expression profiling was done with Affymetrix U133A microarrays and the previously reported ''breast intrinsic''gene set was used for hierarchical clustering and multidimensional scaling to assign molecular class. Results: The basal-like and erbB2+ subgroups were associated with the highest rates of pathologic complete response (CR), 45% [95% confidence interval (95% CI), 24-68] and 45% (95% CI, 23-68), respectively, whereas the luminal tumors had a pathologic CR rate of 6% (95% CI, 1-21). No pathologic CR was observed among the normal-like cancers (95% CI, 0-31). Molecular class was not independent of conventional cliniocopathologic predictors of response such as estrogen receptor status and nuclear grade. None of the 61genes associated with pathologic CR in the basal-like group were associated with pathologic CR in the erbB2+ group, suggesting that the molecular mechanisms of chemotherapy sensitivity may vary between these two estrogen receptor^negative subtypes. Conclusions: The basal-like and erbB2+ subtypes of breast cancer are more sensitive to paclitaxel-and doxorubicin-containing preoperative chemotherapy than the luminal and normallike cancers.Breast cancer is a clinically heterogeneous disease. Histologically similar tumors may have different prognoses and may respond to therapy differently. It is believed that these differences in clinical behavior are due to molecular differences between histologically similar tumors. DNA microarray technology is ideally suited to reveal such molecular differences. A novel molecular classification of breast cancer based on gene expression profiles was recently proposed (1). The investigators identified a set of stably expressed genes (''intrinsic gene set''; n = 534) that accounted for much of the molecular differences between 42 breast cancers and did hierarchical cluster analysis to identify subgroups of cancers with separate gene expression profiles. Luminal, basal-like, normal-like, and erbB2+ subgroups were identified and were shown to have different prognoses (1 -4). These results were confirmed in follow-up experiments by the same group and others using larger numbers of cases. The basal-like (mostly estrogen receptor negative) and erbB2+ (mostly HER-2 amplified and estrogen receptor negative) subgroups had the shortest relapse-free and overall survival, whereas the luminal-type (estrogen receptorpositive) tumors had a more favorable clinical outcome (2 -4).

Sorafenib—a broad tyrosine kinase inhibitor—is the only approved systemic therapy for advanced hepatocellular carcinoma (HCC), but provides limited survival benefits. Recently, immunotherapy has emerged as a promising treatment strategy, but its role remains unclear in HCCs, which are associated with decreased cytotoxic CD8+ T-lymphocyte infiltration in both murine and human tumors. Moreover, we have shown in mouse models that after sorafenib treatment, intratumoral hypoxia is increased and may fuel evasive resistance. Using orthotopic HCC models, we now show that increased hypoxia after sorafenib treatment promotes immunosuppression, characterized by increased intratumoral expression of the immune checkpoint inhibitor programmed death-ligand 1 (PD-L1) and accumulation of T-regulatory cells and M2-type macrophages. We also show that the recruitment of the immunosuppressive cells is mediated in part by hypoxia-induced upregulation of stromal cell-derived 1 alpha (SDF1α). Inhibition of the SDF1α receptor (C-X-C receptor type 4 or CXCR4) using AMD3100 prevented the polarization toward an immunosuppressive microenvironment after sorafenib treatment, inhibited tumor growth, reduced lung metastasis, and improved survival. However, combination of AMD3100 and sorafenib did not significantly change cytotoxic CD8+ T-lymphocyte infiltration into HCC tumors and did not modify their activation status. In separate experiments, antibody blockade of the PD-L1 receptor PD-1 showed anti-tumor effects in treatment-naïve tumors in orthotopic (grafted and genetically engineered) models of HCC. However, anti-PD-1 antibody treatment had additional anti-tumor activity only when combined with sorafenib and AMD3100, and not when combined with sorafenib alone. Conclusion Anti-PD-1 treatment can boost anti-tumor immune responses in HCC models. When used in combination with sorafenib, this immunotherapy approach shows efficacy only with concomitant targeting of the hypoxic and immunosuppressive microenvironment with agents such as CXCR4 inhibitors.

Subcutaneous xenografts have been used for decades to study hepatocellular carcinoma (HCC). These models do not reproduce the specific pathophysiological features of HCCs, which occur in cirrhotic livers that show pronounced necroinflammation, abnormal angiogenesis and extensive fibrosis. As these features are crucial for studying the role of the pathologic host microenvironment in tumor initiation, progression and treatment response, alternative HCC models are desirable. Here we describe a syngeneic orthotopic HCC model in immunocompetent mice with liver cirrhosis induced by carbon tetrachloride (CCl4) that recapitulates key features of human HCC. Induction of substantial hepatic fibrosis requires 12 weeks of CCl4 administration. Intrahepatic implantation of mouse HCC cell lines requires 30 min per mouse. Tumor growth varies by tumor cell line and mouse strain used. Alternatively, tumors can be induced in a genetically engineered mouse model. In this setting, CCl4 is administered for 12 weeks after tail-vein injection of Cre-expressing adenovirus (adeno-Cre) in Stk4−/−Stk3F/− (also known as Mst1−/−Mst2F/−; F indicates a floxed allele) mice, and it results in the development of HCC tumors (hepatocarcinogenesis) concomitantly with liver cirrhosis.