Amy Weise

Combining Human and Rat Sequences in Her-2 DNA Vaccines Blunts Immune Tolerance and Drives Antitumor Immunity

Immune tolerance to tumor-associated self-antigens poses a major challenge in the ability to mount an effective cancer vaccine response. To overcome immune tolerance to HER-2, we formulated DNA vaccines that express both human HER-2 and heterologous rat Neu sequences in separate plasmids or as single hybrid constructs that encode HER-2/Neu fusion proteins. Candidate vaccines were tested in Her-2 transgenic (Tg) mice of BALB/c (BALB), BALB/cxC57BL/6 F1 (F1), or C57BL/6 (B6) background, which exhibit decreasing immune responsiveness to HER-2. Analysis of various cocktails or hybrid vaccines defined a requirement for particular combination of HER/2/Neu sequences to effectively prime immune effector cells in HER-2 Tg mice. In B6 HER-2 Tg mice, rejection of HER-2-positive tumors protected mice from HER-2-negative tumors, providing evidence of epitope spreading. Our findings show that a strategy of combining heterologous antigen with self-antigens could produce a potent DNA vaccine that may be applicable to other tumor-associated antigens.

Expression of estrogenicity genes in a lineage cell culture model of human breast cancer progression

TaqMan Gene Expression assays were used to profile the mRNA expression of estrogen receptor (ERα and ERβ) and estrogen metabolism enzymes including cytosolic sulfotransferases (SULT1E1, SULT1A1, SULT2A1, and SULT2B1), steroid sulfatase (STS), aromatase (CYP19), 17β-hydroxysteroid dehydrogenases (17βHSD1 and 2), CYP1B1, and catechol-O-methyltransferase (COMT) in an MCF10A-derived lineage cell culture model for basal-like human breast cancer progression and in ERα-positive luminal MCF7 breast cancer cells. Low levels of ERα and ERβ mRNA were present in MCF10A-derived cell lines. SULT1E1 mRNA was more abundant in confluent relative to subconfluent MCF10A cells, a non-tumorigenic proliferative breast disease cell line. SULT1E1 was also expressed in preneoplastic MCF10AT1 and MCF10AT1K.cl2 cells, but was markedly repressed in neoplastic MCF10A-derived cell lines as well as in MCF7 cells. Steroid-metabolizing enzymes SULT1A1 and SULT2B1 were only expressed in MCF7 cells. STS and COMT were widely detected across cell lines. Pro-estrogenic 17βHSD1 mRNA was most abundant in neoplastic MCF10CA1a and MCF10DCIS.com cells, while 17βHSD2 mRNA was more prominent in parental MCF10A cells. CYP1B1 mRNA was most abundant in MCF7 cells. Treatment with the histone deacetylase inhibitor trichostatin A (TSA) induced SULT1E1 and CYP19 mRNA but suppressed CYP1B1, STS, COMT, 17βHSD1, and 17βHSD2 mRNA in MCF10A lineage cell lines. In MCF7 cells, TSA treatment suppressed ERα, CYP1B1, STS, COMT, SULT1A1, and SULT2B1 but induced ERβ, CYP19 and SULT2A1 mRNA expression. The results indicate that relative to the MCF7 breast cancer cell line, key determinants of breast estrogen metabolism are differentially regulated in the MCF10A-derived lineage model for breast cancer progression.

Fatal Liver Failure in a Patient on Acetaminophen Treated with Sunitinib Malate and Levothyroxine

Objective: To report the occurrence of fatal acute liver failure following addition of levothyroxine to a regimen of sunitinib and acetaminophen. Case Summary: A 57-year-old woman who started sunitinib treatment for relapsed metastatic gastrointestinal stromal tumor after imatinib failure had disease stabilization and normal livar function through 8 cycles of sunitinib 50 mg/day for 4 weeks, followed by 2 weeks off treatment. Her continuing medications included acetaminophen approximately 4.5 g/wk, as well as standard medications for asthma. In cycle 8, she received oral levothyroxine 50–150 pg/day for approximately 30 days to control hypothyroidism before beginning cycle 9 of sunitinib. On day 4 of cycle 9, she was hospitalized with progressively rising circulating liver enzyme levels. She died 4 days postadmission despite discontinuation of sunitinib and initiation of Intensive supportive treatment. At autopsy, her liver showed severe centrliobular necrosis with moderate-to-severe steatosis and minimal parenchymal invasion by the neoplasm. Viral stains were negative. Discussion: Hepatic failure has been reported rarely in patients receiving sunitinib. Autopsy results excluded neoplastic disease progression and viral infection in the etiology of the event, and the patient may have died of the combined interaction of sunitinib, acetaminophen, and levothyroxine. Although sunitinib was not more than a possible hepatotoxin (Roussel Uclaf Causality Assessment Method) and may even have been hepatoprotective over a 48-week period against chronic intake of acetaminophen (probable hepatotoxin) by producing regional hypothyroidism within the liver, it is hypothesized that correction of the putative hepatic hypothyroidism with oral levothyroxine (possible hepatotoxin) and reinitiation of sunitinib treatment may have triggered hepatic necrosis. Conclusions: Acetaminophen should be used with particular caution in patients receiving sunitinib. In sunitinib-treated patients who also require levothyroxine therapy, increased caution in restarting subsequent sunitinib treatment and discontinuation of acetaminophen, if possible, is advisable. Further evaluation of this potential interaction is warranted.

Prospects of Controlling Breast Cancer Metastasis by Immune Intervention

Different immune effectors control distinct steps in tumor metastasis; T cells inhibit the growth of primary and metastatic tumors, while NK control tumor cells in transit. Vaccination with DNA encoding Her-2 which is expressed on primary and metastasized breast cancer cells induced both humoral and cellular immunity to inhibit tumor growth. Vaccination efficacy can be amplified by depleting CD4;+CD25;+Foxp3;+ regulatory T cells (Treg), but the risk of inducing autoimmunity warrants new strategies to selectively amplify anti-tumor immunity when modulating Treg. In the tumors, the major cyclooxygenase (COX)-2 product is prostaglandin E2(PGE2) which suppresses T and NK cells while amplifying Treg. These cellular responses to PGE2 are mediated through four E prostanoid (EP) receptors. Cox inhibitors and EP antagonists enhance NK activity to inhibit tumor metastasis; but they may down regulate MHC class I expression. Since T and NK cells have opposite requirements for MHC class I expression, their relative contribution to cancer control may vary with the stage of the disease. To enhance tumor infiltration by immune effectors, the role of CXCL9 is discussed. The complex nature of tumor metastasis necessitates a comprehensive approach to achieve successful immune intervention.

Her-2 DNA versus cell vaccine: immunogenicity and anti-tumor activity

Direct comparison and ranking of vaccine formulations in pre-clinical studies will expedite the identification of cancer vaccines for clinical trials. Two human ErbB-2 (Her-2) vaccines, naked DNA and whole cell vaccine, were tested side-by-side in wild type and Her-2 transgenic mice. Both vaccines can induce humoral and cellular immunity to the entire repertoire of Her-2 epitopes. Mice were electro-vaccinated i.m. with a mixture of pGM-CSF and pE2TM, the latter encodes Her-2 extracellular and transmembrane domains. Alternatively, mice were injected i.p. with human ovarian cancer SKOV3 cells that have amplified Her-2. In wild type mice, comparable levels of Her-2 antibodies (Ab) were induced by these two vaccines. However, T cell immunity and protection against Her-2+ tumors were superior in DNA vaccinated mice. In BALB Her-2 transgenic (Tg) mice, which were tolerant to Her-2, DNA and cell vaccines were administered after regulatory T cells (Treg) were removed by anti-CD25 mAb. Again, comparable levels of Her-2 Ab were induced, but DNA vaccines rendered greater anti-tumor activity. In B6xDR3 Her-2 Tg mice that expressed the autoimmune prone HLA-DR3 allele, higher levels of Her-2 Ab were induced by SKOV3 cell than by Her-2 DNA. But anti-tumor activity was still more profound in DNA vaccinated mice. Therefore, Her-2 DNA vaccine induced greater anti-tumor immunity than cell vaccine, whether mice were tolerant to Her-2 or susceptible to autoimmunity. Through such side-by-side comparisons in appropriate pre-clinical test systems, the more effective vaccine formulations will emerge as candidates for clinical trials.

Possible case of levofloxacin-induced thrombocytopenia

PURPOSEnA possible case of levofloxacin-induced thrombocytopenia is reported.nnnSUMMARYnA 73-year-old Caucasian woman with stage IV squamous cell cancer of the oral cavity arrived at the hospital with a 6-day history of epistaxis; petechiae over her arms, legs, and abdomen; and bruises over her forearms. Her comorbidities included hypertension, type 2 diabetes mellitus, and coronary artery disease. Two weeks before arrival at the hospital, the patient had been admitted to the hospital with community-acquired pneumonia (CAP) and given a 10-day course of levofloxacin 500 mg daily, which she completed 4 days before this admission. Her platelet count was 7,000 cells/mm(3) on admission. Her home medications included aspirin 325 mg daily, ranitidine 150 mg twice daily, alprazolam 0.25 mg daily, and methadone 10 mg twice daily. She last received cetuximab six weeks before this hospital admission. No other new medications were recently introduced. She had no known drug allergies and no recent heparin exposure. The patient was given a platelet transfusion and treated empirically with prednisone for possible immune thrombocytopenic purpura, though drug-induced thrombocytopenia (DIT) was also suspected. She was restarted on her home medications except for aspirin. She was discharged with a 7-day course of oral corticosteroids. At discharge, her platelet count was 38,000 cells/mm(3). Corticosteroids were discontinued when DIT was established to be the most likely diagnosis.nnnCONCLUSIONnA 73-year-old woman with stage IV squamous cell cancer of the oral cavity developed a possible case of levofloxacin-induced thrombocytopenia after receiving the drug for 10 days for treatment of CAP.

Intratumoral DNA electroporation induces anti-tumor immunity and tumor regression

In situ expression of a foreign antigen and an immune-modulating cytokine by intratumoral DNA electroporation was tested as a cancer therapy regimen. Transgene expression in the tumors was sustained for 2–3xa0weeks after intratumoral electroporation with mammalian expression plasmid containing firefly luciferase cDNA. Electroporation with cDNA encoding tetanus toxin fragment C (TetC) induced tetanus toxin-binding antibody, demonstrating immune recognition of the transgene product. Intratumoral electroporation with TetC and IL-12 cDNA after mice were treated with CD25 mAb to remove regulatory T cells induced IFN-γ producing T-cell response to tumor-associated antigen, heavy inflammatory infiltration, regression of established tumors and immune memory to protect mice from repeated tumor challenge. Intratumoral expression of immune-modulating molecules may be most suitable in the neoadjuvant setting to enhance the therapeutic efficacy and provide long-term protection.

Induction of HER2 Immunity in Outbred Domestic Cats by DNA Electrovaccination

Gibson and colleagues show that outbred domestic cats develop mammary tumors similar to those in humans. Electrovaccination of heterologous or point-mutated feline HER2 DNA overcomes T-cell immune tolerance in 40% of healthy cats and induces antibodies with distinct specificity. Domestic cats share human living environments and genetic traits. They develop spontaneous feline mammary carcinoma (FMC) with similar histopathology to human breast cancer. HER2 and AKT phosphorylation was demonstrated in primary FMC by immunoblot analysis, indicating HER2 as a therapeutic target. FMC lines K12 and K248 expressing HER1, HER2, and HER3 were sensitive to receptor tyrosine kinase (RTK) inhibitors gefitinib and lapatinib. To test HER2 vaccine response in cats, purpose-bred, healthy cats were electrovaccinated with heterologous (xenogeneic) or point-mutated feline HER2 DNA. T-cell reactivity to feline self-HER2 was detected in 4 of 10 cats that received bear HER2, human–rat fusion HER2 (E2Neu) or mutant feline HER2 (feHER2-K), which contains a single amino acid substitution. The variable T-cell responses may resemble that in the genetically heterogeneous human population. All immune sera to heterologous HER2 recognized feline HER2 expressed in 3T3 cells (3T3/HER2), but not that in FMC K12 or K248. Immune sera to mutant pfeHER2-K bound 3T3/HER2 cells weakly, but they showed better recognition of K12 and K248 cells that also express HER1 and HER3, suggesting distinct HER2 epitopes displayed by FMC that may be simulated by feHER2-K. In summary, HER2 DNA electroporation overcomes T-cell immune tolerance in approximately 40% of healthy cats and induces antibodies with distinct specificity. Vaccination studies in domestic cats can expedite vaccine iteration to guide human vaccine design and better predict outcome, with the added benefit of helping feline mammary tumor patients. Cancer Immunol Res; 3(7); 777–86. ©2015 AACR.