Parathyroid Carcinoma Presenting as Recurrent Primary Hyperparathyroidism and Neck Mass: A Case Report.

Parathyroid carcinoma is a rare endocrine neoplasm that accounts for <1% of cases of primary hyperparathyroidism. The management of parathyroid carcinoma is a challenge due to the high rate of local recurrence of the tumour. We report the case of a middle-aged north Indian woman who presented with recurrent primary hyperparathyroidism due to parathyroid carcinoma. She presented with a recurrent palpable hard neck mass and underwent radical dissection of the neck six times. At the time of writing this report, she was referred for external beam radiotherapy to the neck. Parathyroid carcinoma is a rare malignancy with an indolent but tenacious course. Complete resection at the time of initial surgery determines the prognosis of the neoplasm. Chemotherapy and radiotherapy are usually ineffective. Hypercalcaemia needs to be aggressively managed. A multidisciplinary team is required to effectively manage parathyroid carcinoma.

Management and outcomes of ureteroceles in children: An experience of 25 years.

INTRODUCTION: Ureterocele is a rare urogenital malformation. The treatment is variable and complicated as it depends on several factors. The aim of this study was to evaluate the management and outcomes of children with ureterocele and to compare single system and duplex system ureteroceles. MATERIALS AND METHODS: A retrospective study was conducted and all patients with ureterocele operated from January 1992 to December 2018 were included. The records of those included were assessed, and a detailed case record sheet was filled. The outcome parameters assessed were the persistence of symptoms and additional surgical procedure performed. RESULTS: Forty-seven patients (28 boys and 19 girls) with a median age of presentation of 21 months were included. Four patients had bilateral ureterocele. Overall, 51 renal units with ureterocele were studied. Twenty renal units of the 31 renal units with duplex system underwent cystoscopic decompression, and of these, 8 (40%) needed a second procedure. Fourteen renal units of the remaining 20 renal units with single system underwent cystoscopy and decompression, and of these, 1 (7%) required another procedure (P = 0.024). Sixteen renal units had ectopic ureterocele, of which 9 (56%) underwent heminephrectomy/nephrectomy. Intravesical ureterocele was present in 35 renal units, of which only 2 (5.7%) underwent nephrectomy or heminephrectomy (P < 0.001). CONCLUSION: Duplex system ureteroceles are more likely to require a second procedure following an endoscopic puncture. Units with ectopic ureterocele were more likely to need nephrectomy.

The Composite Planning Technique in Left Sided Breast Cancer Radiotherapy: A Dosimetric Study.

OBJECTIVE: The aim of this retrospective study is to reduce the dose of heart, both lung and opposite breast and left anterior descending artery (LAD) and avoid long term complication and radiation induced secondary malignancies in radiotherapy left breast/chest wall without losing homogeneity and conformity of the Planning Target Volume (PTV), contoured using Radiotherapy Oncology Group (RTOG 1005) guideline. MATERIALS AND METHODS: The treatment plans were generated retrospectively by TFIF, VMAT and Composite techniques for 30 patients. Dose-Volume Histograms (DVHs) were evaluated for PTV and organs at risk (OAR's) and analyzed in two groups BCS and MRM using Wilcoxon signed rank test. RESULTS: The homogeneity index (HI) was improved in Composite technique by 32.72% and 21.81% of VMAT, 50.66% and 49.41% of TFIF in BCS and MRM group respectively. The Conformity Index (CI) for composite plan was statistically same as VMAT and superior by 27.94% and 41.37% of TFIF in BCS and MRM group respectively. The low dose volume V5Gy and V10Gy of the heart were improved in Composite plan by 47.9% and 26.1% of VMAT respectively in BCS group and in MRM group, improved by 21.2% and 45.6% of VMAT. The V5Gy and V10Gy of ipsilateral lung were improved in Composite plan by 16% and 13.7% of VMAT respectively in BCS and 8.4% and 3% of VMAT respectively in MRM group. CONCLUSION: The Composite plan consisting of VMAT and TFIF plan with an optimum selection of fractions can achieve lower low dose exposure to the OAR's without compromising coverage compared to VMAT.

Therapeutic cooperation between auranofin, a thioredoxin reductase inhibitor and anti-PD-L1 antibody for treatment of triple-negative breast cancer.

Triple-negative breast cancer (TNBCs) is a very aggressive and lethal form of breast cancer with no effective targeted therapy. Neoadjuvant chemotherapies and radiotherapy remains a mainstay of treatment with only 25-30% of TNBC patients responding. Thus, there is an unmet clinical need to develop novel therapeutic strategies for TNBCs. TNBC cells have increased intracellular oxidative stress and suppressed glutathione, a major antioxidant system, but still, are protected against higher oxidative stress. We screened a panel of antioxidant genes using the TCGA and METABRIC databases and found that expression of the thioredoxin pathway genes is significantly upregulated in TNBC patients compared to non-TNBC patients and is correlated with adverse survival outcomes. Treatment with auranofin (AF), an FDA-approved thioredoxin reductase inhibitor caused specific cell death and impaired the growth of TNBC cells grown as spheroids. Furthermore, AF treatment exerted a significant in vivo antitumor activity in multiple TNBC models including the syngeneic 4T1.2 model, MDA-MB-231 xenograft and patient-derived tumor xenograft by inhibiting thioredoxin redox activity. We, for the first time, showed that AF increased CD8+Ve T-cell tumor infiltration in vivo and upregulated immune checkpoint PD-L1 expression in an ERK1/2-MYC-dependent manner. Moreover, combination of AF with anti-PD-L1 antibody synergistically impaired the growth of 4T1.2 primary tumors. Our data provide a novel therapeutic strategy using AF in combination with anti-PD-L1 antibody that warrants further clinical investigation for TNBC patients.

Blockade of ErbB2 and PD-L1 using a bispecific antibody to improve targeted anti-ErbB2 therapy.

A significant proportion of human epidermal growth factor receptor 2 (Her2/ErbB2)-positive metastatic breast cancer patients are refractory to Her2-targeted trastuzumab-like therapy. Some of this resistance has been attributed to the upregulation of immune checkpoints such as programmed cell death-1 (PD-1) and its ligand, PD-L1 in Her2-positive breast cancer patients. Therefore, therapies targeting both the PD-1/PD-L1 interaction and oncogenic Her2 signaling are of significant clinical interest. Here, we constructed a mouse bispecific antibody targeting PD-L1 and rat Her2 (referred to as BsPD-L1xrErbB2) aiming to redirect the anti-PD-L1 response toward Her2-expressing tumor cells. BsPD-L1xrErbB2 demonstrated additive binding to interferon (IFN)-γ treated Her2+ TUBO tumor cells, but it did not affect the proliferation of tumor cells in-vitro. BsPD-L1xrErbB2 also blocked the PD-1/PD-L1 interaction. This bispecific antibody was constructed with a mouse IgG2a Fc backbone and interacted with Fcγ receptors and resulted in complement deposition (C3). ADCC and complement action could be potential mechanisms of action of this molecule. BsPD-L1xrErbB2 successfully reduced TUBO tumor growth and increased tumor rejection rate compared to the monovalent anti-PD-L1, monovalent anti-ErbB2 or the combination of anti-PD-L1 and anti-ErbB2 monotherapies. The enhanced anti-tumor effect of BsPD-L1xrErbB2 was dependent on CD8+ T lymphocytes and IFN-γ, as depletion of CD8+ T lymphocytes and neutralization of IFN-γ completely abolished the antitumor activity of the bispecific antibody. Consistently, BsPD-L1xrErbB2 treatment also increased the frequency of intratumor CD8+ T lymphocytes. Taken together, our data support a bispecific antibody approach to enhance the anti-tumor efficacy of PD-1/PD-L1 checkpoint blockade in Her2-positive metastatic breast cancers.

CD96 Is an Immune Checkpoint That Regulates CD8+ T-cell Antitumor Function.

CD96 is a novel target for cancer immunotherapy shown to regulate NK cell effector function and metastasis. Here, we demonstrated that blocking CD96 suppressed primary tumor growth in a number of experimental mouse tumor models in a CD8+ T cell-dependent manner. DNAM-1/CD226, Batf3, IL12p35, and IFNγ were also critical, and CD96-deficient CD8+ T cells promoted greater tumor control than CD96-sufficient CD8+ T cells. The antitumor activity of anti-CD96 therapy was independent of Fc-mediated effector function and was more effective in dual combination with blockade of a number of immune checkpoints, including PD-1, PD-L1, TIGIT, and CTLA-4. We consistently observed coexpression of PD-1 with CD96 on CD8+ T lymphocytes in tumor-infiltrating leukocytes both in mouse and human cancers using mRNA analysis, flow cytometry, and multiplex IHF. The combination of anti-CD96 with anti-PD-1 increased the percentage of IFNγ-expressing CD8+ T lymphocytes. Addition of anti-CD96 to anti-PD-1 and anti-TIGIT resulted in superior antitumor responses, regardless of the ability of the anti-TIGIT isotype to engage FcR. The optimal triple combination was also dependent upon CD8+ T cells and IFNγ. Overall, these data demonstrate that CD96 is an immune checkpoint on CD8+ T cells and that blocking CD96 in combination with other immune-checkpoint inhibitors is a strategy to enhance T-cell activity and suppress tumor growth.

Blockade of PDGFRß circumvents resistance to MEK-JAK inhibition via intratumoral CD8+ T-cells infiltration in triple-negative breast cancer.

BACKGROUND: Despite the increasing progress in targeted and immune based-directed therapies for other solid organ malignancies, currently there is no targeted therapy available for TNBCs. A number of mechanisms have been reported both in pre-clinical and clinical settings that involve inherent, acquired and adaptive resistance to small molecule inhibitors. Here, we demonstrated a novel resistance mechanism in TNBC cells mediated by PDGFRß in response to JAK2 inhibition. METHODS: Multiple in vitro (subG1, western blotting, immunofluorescence, RT-PCR, Immunoprecipitation), in vivo and publically available datasets were used. RESULTS: We showed that TNBC cells exposed to MEK1/2-JAK2 inhibitors exhibit resistant colonies in anchorage-independent growth assays. Moreover, cells treated with various small molecule inhibitors including JAK2 promote PDGFRß upregulation. Using publically available databases, we showed that patients expressing high PDGFRß or its ligand PDGFB exhibit poor relapse-free survival upon chemotherapeutic treatment. Mechanistically we found that JAK2 expression controls steady state levels of PDGFRß. Thus, co-blockade of PDGFRß with JAK2 and MEK1/2 inhibitors completely eradicated resistant colonies in vitro. We found that triple-combined treatment had a significant impact on CD44+/CD24- stem-cell-like cells. Likewise, we found a significant tumor growth inhibition in vivo through intratumoral CD8+ T cells infiltration in a manner that is reversed by anti-CD8 antibody treatment. CONCLUSION: These findings reveal a novel regulatory role of JAK2-mediated PDGFRß proteolysis and provide an example of a PDGFRß-mediated resistance mechanism upon specific target inhibition in TNBC.

The immune checkpoint CD96 defines a distinct lymphocyte phenotype and is highly expressed on tumor-infiltrating T cells.

CD96 has recently been shown to be a potent immune checkpoint molecule in mice, but a similar role in humans is not known. In this study, we provide a detailed map of CD96 expression across human lymphocyte lineages, the kinetics of CD96 regulation on T-cell activation and co-expression with other conventional and emerging immune checkpoint molecules. We show that CD96 is predominantly expressed by T cells and has a unique lymphocyte expression profile. CD96high T cells exhibited distinct effector functions on activation. Of note, CD96 expression was highly correlated with T-cell markers in primary and metastatic human tumors and was elevated on antigen-experienced T cells and tumor-infiltrating lymphocytes. Collectively, these data demonstrate that CD96 may be a promising immune checkpoint to enhance T-cell function against human cancer and infectious disease.

Overcoming Acquired PD-1/PD-L1 Resistance with CD38 Blockade.

Overexpression of CD38 after PD-1/PD-L1 blockade increases extracellular adenosine levels and may contribute to acquired resistance to anti-PD-1/PD-L1 therapy. Cancer Discov; 8(9); 1066-8. ©2018 AACRSee related article by Chen et al., p. 1156.

CEP55 is a determinant of cell fate during perturbed mitosis in breast cancer.

The centrosomal protein, CEP55, is a key regulator of cytokinesis, and its overexpression is linked to genomic instability, a hallmark of cancer. However, the mechanism by which it mediates genomic instability remains elusive. Here, we showed that CEP55 overexpression/knockdown impacts survival of aneuploid cells. Loss of CEP55 sensitizes breast cancer cells to anti-mitotic agents through premature CDK1/cyclin B activation and CDK1 caspase-dependent mitotic cell death. Further, we showed that CEP55 is a downstream effector of the MEK1/2-MYC axis. Blocking MEK1/2-PLK1 signaling therefore reduced outgrowth of basal-like syngeneic and human breast tumors in in vivo models. In conclusion, high CEP55 levels dictate cell fate during perturbed mitosis. Forced mitotic cell death by blocking MEK1/2-PLK1 represents a potential therapeutic strategy for MYC-CEP55-dependent basal-like, triple-negative breast cancers.

Deficiency of host CD96 and PD-1 or TIGIT enhances tumor immunity without significantly compromising immune homeostasis.

Multiple non-redundant immunosuppressive pathways co-exist in the tumor microenvironment and their co-targeting can increase clinical responses. Indeed, concurrent blockade of CTLA-4 and PD-1 in patients with advanced melanoma increased clinical responses over monotherapy alone although the frequency and severity of immune related adverse events (irAEs) also increased. Nevertheless, a substantial number of patients still display an innate resistance phenotype and are unresponsive to current approved immunotherapies even when utilized in combination. In this study, we generated Pdcd1-/-CD96-/- and Tigit-/-CD96-/- mice to investigate how loss of CD96 in combination with PD-1 or TIGIT impacts on immune homeostasis and hence the potential of inducing immune related toxicities following co-targeting of these pairs of receptors. The ability of Pdcd1-/-CD96-/- and Tigit-/-CD96-/- mice to suppress primary tumor growth was also assessed using the MC38 colon carcinoma and SM1WT1 BRAF-mutated melanoma tumor models. Both Pdcd1-/-CD96-/- or Tigit-/-CD96-/- mice displayed no overt perturbations in immune homeostasis over what was previously reported with Pdcd1-/- or Tigit-/- mice even when aged for 22 months. Interestingly, increased suppression of subcutaneous tumor growth and complete responses was seen in Pdcd1-/-CD96-/- mice compared to Pdcd1-/- or CD96-/- mice depending upon the tumor model. In contrast, in these models, growth suppression in Tigit-/-CD96-/- were similar to Tigit-/- or CD96-/- . This enhanced anti-tumor efficacy of Pdcd1-/-CD96-/- appeared to be due to favorable changes in the ratio of CD8+ T cells to T regulatory cells or CD11b+GR-1hi myeloid cells in the tumor microenvironment. Co-targeting CD96 and PD-1 may increase anti-tumor immunity over targeting PD-1 alone and potentially not induce serious immune-related toxicities and thus appears a promising strategy for clinical development.

CD96 targeted antibodies need not block CD96-CD155 interactions to promote NK cell anti-metastatic activity.

CD96 is a transmembrane glycoprotein Ig superfamily receptor, expressed on various T cell subsets and NK cells, that interacts with nectin and nectin-like proteins, including CD155/polio virus receptor (PVR). Here, we have compared three rat anti-mouse CD96 mAbs, including two that block CD96-CD155 (3.3 and 6A6) and one that does not block CD96-CD155 (8B10). Using flow cytometry, we demonstrated that both mAbs 3.3 and 6A6 bind to the first Ig domain of mouse CD96 and compete with CD155 binding, while mAb 8B10 binds to the second Ig domain and does not block CD155. While Fc isotype was irrelevant concerning the anti-metastatic activity of 3.3 mAb, in four different experimental metastases models and one spontaneous metastasis model, the relative order of anti-metastatic potency was 6A6 > 3.3 > 8B10. The metastatic burden control of all of the anti-CD96 clones was highly dependent on NK cells and IFN-γ. Consistent with its inability to block CD96-CD155 interactions, 8B10 retained anti-metastatic activity in CD155-deficient mice, whereas 3.3 and 6A6 lost potency in CD155-deficient mice. Furthermore, 8B10 retained most of its anti-metastatic activity in IL-12p35-deficient mice whereas the activity of 3.3 and 6A6 were partially lost. All three mAbs were inactive in CD226-deficient mice. Altogether, these data demonstrate anti-CD96 need not block CD96-CD155 interactions (ie. immune checkpoint blockade) to promote NK cell anti-metastatic activity.

Temporal Regulation of Natural Killer T Cell Interferon Gamma Responses by ß-Catenin-Dependent and -Independent Wnt Signaling.

Natural killer T (NKT) cells are prominent innate-like lymphocytes in the liver with critical roles in immune responses during infection, cancer, and autoimmunity. Interferon gamma (IFN-γ) and IL-4 are key cytokines rapidly produced by NKT cells upon recognition of glycolipid antigens presented by antigen-presenting cells (APCs). It has previously been reported that the transcriptional coactivator ß-catenin regulates NKT cell differentiation and functionally biases NKT cell responses toward IL-4, at the expense of IFN-γ production. ß-Catenin is not only a central effector of Wnt signaling but also contributes to other signaling networks. It is currently unknown whether Wnt ligands regulate NKT cell functions. We thus investigated how Wnt ligands and ß-catenin activity shape liver NKT cell functions in vivo in response to the glycolipid antigen, α-galactosylceramide (α-GalCer) using a mouse model. Pharmacologic targeting of ß-catenin activity with ICG001, as well as myeloid-specific genetic ablation of Wntless (Wls), to specifically target Wnt protein release by APCs, enhanced early IFN-γ responses. By contrast, within several hours of α-GalCer challenge, myeloid-specific Wls deficiency, as well as pharmacologic targeting of Wnt release using the small molecule inhibitor IWP-2 impaired α-GalCer-induced IFN-γ responses, independent of ß-catenin activity. These data suggest that myeloid cell-derived Wnt ligands drive early Wnt/ß-catenin signaling that curbs IFN-γ responses, but that, subsequently, Wnt ligands sustain IFN-γ expression independent of ß-catenin activity. Our analyses in ICG001-treated mice confirmed a role for ß-catenin activity in driving early IL-4 responses by liver NKT cells. However, neither pharmacologic nor genetic perturbation of Wnt production affected the IL-4 response, suggesting that IL-4 production by NKT cells in response to α-GalCer is not driven by released Wnt ligands. Collectively, these data reveal complex temporal roles of Wnt ligands and ß-catenin signaling in the regulation of liver NKT cell activation, and highlight Wnt-dependent and -independent contributions of ß-catenin to NKT cell functions.

Interleukin-12 from CD103+ Batf3-Dependent Dendritic Cells Required for NK-Cell Suppression of Metastasis.

Several host factors may affect the spread of cancer to distant organs; however, the intrinsic role of dendritic cells (DC) in controlling metastasis is poorly described. Here, we show in several tumor models that although the growth of primary tumors in Batf3-deficient mice, which lack cross-presenting DCs, was not different from primary tumors in wild-type (WT) control mice, Batf3-deficient mice had increased experimental and spontaneous metastasis and poorer survival. The increased metastasis was independent of CD4+ and CD8+ T lymphocytes, but required NK cells and IFNγ. Chimeric mice in which Batf3-dependent DCs uniformly lacked the capacity to produce IL12 had metastatic burdens similar to the Batf3-deficient mice, suggesting that Batf3+ DCs were the only cell type whose IL12 production was critical for controlling metastasis. We found that IL12-YFP reporter mice, whose lungs were injected with B16F10 melanoma, had increased numbers of IL12-expressing CD103+ DCs with enhanced CD86 expression. Bone-marrow-derived DCs from WT, but not Batf3-deficient, mice activated NK cells to produce IFNγ in an IL12-dependent manner and therapeutic injection of recombinant mouse IL12 decreased metastasis in both WT and Batf3-deficient mice. Analysis of TCGA datasets revealed an association between high expression of BATF3 and IRF8 and improved survival of breast cancer patients; BATF3 expression also significantly correlated with NK-cell receptor genes, IL12, and IFNG Collectively, our findings show that IL12 from CD103+ DCs is critical for NK cell-mediated control of tumor metastasis. Cancer Immunol Res; 5(12); 1098-108. ©2017 AACR.

Pre-operative Hepatic Artery Resistive Index is a Non-invasive Predictive Indicator of Prognosis in Biliary Atresia.

AIMS: The aim of this study is to evaluate hepatic artery resistive index (HARI) as a noninvasive prognostic predictor by correlating it with peripheral blood nitric oxide (NO) levels, portal pressure (PP) and histopathological changes in the liver in patients of biliary atresia (BA). MATERIALS AND METHODS: Twenty-five patients were included in the study prospectively from November 2012 to June 2014. All patients underwent Doppler sonography to calculate the HARI preoperatively. Peripheral blood NO was also measured preoperatively. Biochemical liver function tests (LFTs) were measured preoperatively and at 1, 3, and 6 months postoperatively. The PP was measured intraoperatively, and a liver biopsy was taken in all patients. Disappearance of jaundice defined successful surgical treatment. Postoperatively, a hepatobiliary IminoDiacetic Acid scan (HIDA) was done to demonstrate a patent bilio-enteric pathway. RESULTS: The mean preoperative HARI was 0.78 ± 0.105, and the median was 0.80 (range 0.60-1.0). The median HARI was used to correlate the other parameters; 13 (52%) patients had HARI ≥0.8. The mean PP was 24.96 ± 6.54 mmHg. The HARI had a strong correlation with PP (P = 0.0001) and (NO) (P = 0.0001); with every 0.1 increase in HARI, there was 5.2 mmHg increase in PP and 3.8 µmol/L increase in NO. The histological parameters which reached significance in relation to HARI were hepatocellular damage, bile duct inflammation, portal inflammation, and portal fibrosis. The postoperative improvement in LFT was significantly better in patients with HARI <0.8. All four patients who died during or after the study period had HARI >0.8, elevated PP, and NO levels. CONCLUSIONS: Preoperative HARI was found to have a direct correlation with PP and peripheral blood NO as a measure of portal hypertension. A preoperative HARI ≥0.8 should be considered as a risk factor for poor outcomes in BA.

CD73 Promotes Resistance to HER2/ErbB2 Antibody Therapy.

Expression of the ectonucleotidase CD73 by tumor cells, stromal cells, and immune cells is associated in cancer with immune suppression. In this study, we investigated the role of CD73 on the activity of the anti-HER2/ErbB2 monoclonal antibody (mAb) trastuzumab. In a prospective, randomized phase III clinical trial evaluating the activity of trastuzumab, high levels of CD73 gene expression were associated significantly with poor clinical outcome. In contrast, high levels of PD-1 and PD-L1 were associated with improved clinical outcome. In immunocompetent mouse models of HER2/ErbB2-driven breast cancer, CD73 expression by tumor cells and host cells significantly suppressed immune-mediated responses mediated by anti-ErbB2 mAb. Furthermore, anti-CD73 mAb therapy enhanced the activity of anti-ErbB2 mAb to treat engrafted or spontaneous tumors as well as lung metastases. Gene ontology enrichment analysis from gene-expression data revealed a positive association of CD73 expression with extracellular matrix organization, TGFß genes, epithelial-to-mesenchymal transition (EMT) transcription factors and hypoxia-inducible-factor (HIF)-1 gene signature. Human mammary cells treated with TGFß or undergoing EMT upregulated CD73 cell-surface expression, confirming roles for these pathways. In conclusion, our findings establish CD73 in mediating resistance to trastuzumab and provide new insights into how CD73 is regulated in breast cancer. Cancer Res; 77(20); 5652-63. ©2017 AACR.

Pharmacological targeting of the transcription factor SOX18 delays breast cancer in mice.

Pharmacological targeting of transcription factors holds great promise for the development of new therapeutics, but strategies based on blockade of DNA binding, nuclear shuttling, or individual protein partner recruitment have yielded limited success to date. Transcription factors typically engage in complex interaction networks, likely masking the effects of specifically inhibiting single protein-protein interactions. Here, we used a combination of genomic, proteomic and biophysical methods to discover a suite of protein-protein interactions involving the SOX18 transcription factor, a known regulator of vascular development and disease. We describe a small-molecule that is able to disrupt a discrete subset of SOX18-dependent interactions. This compound selectively suppressed SOX18 transcriptional outputs in vitro and interfered with vascular development in zebrafish larvae. In a mouse pre-clinical model of breast cancer, treatment with this inhibitor significantly improved survival by reducing tumour vascular density and metastatic spread. Our studies validate an interactome-based molecular strategy to interfere with transcription factor activity, for the development of novel disease therapeutics.

Adenosine 2B Receptor Expression on Cancer Cells Promotes Metastasis.

Adenosine plays an important role in inflammation and tumor development, progression, and responses to therapy. We show that an adenosine 2B receptor inhibitor (A2BRi) decreases both experimental and spontaneous metastasis and combines with chemotherapy or immune checkpoint inhibitors in mouse models of melanoma and triple-negative breast cancer (TNBC) metastasis. Decreased metastasis upon A2BR inhibition is independent of host A2BR and lymphocytes and myeloid cells. Knockdown of A2BR on mouse and human cancer cells reduces their metastasis in vivo and decreases their viability and colony-forming ability, while transiently delaying cell-cycle arrest in vitro The prometastatic activity of adenosine is partly tumor A2BR dependent and independent of host A2BR expression. In humans, TNBC cell lines express higher A2BR than luminal and Her2(+) breast cancer cell lines, and high expression of A2BR is associated with worse prognosis in TNBC. Collectively, high A2BR on mouse and human tumors promotes cancer metastasis and is an ideal candidate for therapeutic intervention. Cancer Res; 76(15); 4372-82. ©2016 AACR.

Improved Treatment of Breast Cancer with Anti-HER2 Therapy Requires Interleukin-21 Signaling in CD8+ T Cells.

The HER2/ErbB2 monoclonal antibody (mAb) trastuzumab is combined with chemotherapy as a standard-of-care for newly diagnosed HER2(+) breast cancer patients, but some patients treated with this combination therapy experience early relapse. Our analysis of data from a clinical trial evaluating the efficacy of chemotherapy plus/minus trastuzumab suggested that the magnitude of trastuzumab benefit on distant disease-free survival was higher for increasing expression of the IL21 receptor (IL21R). Therefore, we investigated a possible role for IL21 signaling in promoting HER2 mAb therapeutic efficacy. We found that IL21R-deficient mice and wild-type mice treated with a neutralizing anti-IL21 mAb were less susceptible to trastuzumab-like anti-ErbB2 therapy. Furthermore, IL21R expression on CD8(+) T cells, but not on natural killer cells, was required for optimal anti-ErbB2 mAb efficacy, and IL21 expression was enhanced in tumor-infiltrating CD4(+) T lymphocytes after anti-ErbB2 therapy. Finally, we found that administering recombinant IL21 in combination with anti-ErbB2 therapy was therapeutic against primary tumors and experimental metastases in mice. Collectively, our findings suggest that elevating IL21 signaling may enhance trastuzumab efficacy, thus constituting a novel candidate strategy to overcome trastuzumab resistance and improve patient survival. Cancer