Organ-specific expression of the colon cancer antigen A33, a cell surface target for antibody-based therapy

Monoclonal antibody mAbA33 recognizes a unique cell surface protein of colorectal cancer, the A33 antigen. Phase I/II studies have shown highly selective targeting of radio-labeled mAbA33 in patients with metastatic colorectal cancer, opening up the possibility of A33-directed therapy. To better understand the basis of selective mAbA33 targeting in patients, the present study was designed to define the A33 distribution in normal organs and examine A33 expression in a broad range of tumor types. Immunohistochemical analysis of normal tissues identified the large and small intestinal mucosa as the principal sites of A33 expression. Tests with over 450 tumor samples showed that only tumors of the gastrointestinal tract are consistently A33-positive. For example, A33 is found in 95% of primary and metastatic colorectal cancers (86 of 90 cases tested), with uniform expression throughout the tumors in most cases. A33 was detected in a subset of gastric cancers (14/24 cases), with uniform expression in 10 cases (including 5 signer ring adenocarcinomas). Among esophageal cancers, squamous cell tumors typed A33-negative (9 cases), whereas one case each of mucinous and intestinal type was A33-positive. A subset of pancreatic carcinomas (6/12 cases) showed A33 expression, although with marked heterogeneity. Other epithelial cancers, sarcomas, neuroectodermal tumors, and lymphoid neoplasms were generally A33-negative. A33 is the first example of a constitutively expressed, organ-specific epithelial membrane antigen permitting highly specific tumor targeting in patients with colorectal cancer.

Distinctive Expression of Cancer/Testis-X Antigens in a Subset of ER Negative Breast Carcinomas

Background: Cancer/testis-X antigens are a multigene family that are predominantly expressed in human germ line cells, with little or no expression in somatic adult tissues, but become aberrantly activated in various malignancies. Some such CT-X antigens represent ideal targets for cancer immunotherapy and have already been used in clinical testing. In contrast to melanomas, bladder, lung, ovarian and hepatocellular carcinomas which show higher levels of CT-X antigen expression, the reports in breast cancers have been inconclusive to date and a comprehensive gene expression and clinicopathological analysis has yet to be performed.Material and Methods: Using sequencing data as well as nine publicly available gene expression data sets, we analyzed the expression of Cancer/testis-X antigens in more than 1900 primary breast cancers. Complementary analysis was performed on three tissue microarrays comprising a total of 201 primary breast carcinomas and 53 brain metastases. Clinical information on the ER-, PR-, HER2, Ki67, p53, EGFR and basal markers was available for statistical analysis.Results: A significantly higher expression of Cancer/testis-X antigens was found in ER negative breast carcinomas over different data sets with a concordant gene expression pattern of several Cancer/testis-X antigens. Members of the MAGEA family and NY-ESO-1/CTAG1B were consistently the most prevalent. Immunohistochemical analyses confirmed a significant correlation of MAGEA family and NY-ESO-1/CTAG1B with ER negative (pValue < 0.0001), PR negative (pValue < 0.01) and Ki67 staining (pValue < 0.0001). Many of these tumors were also positive for basal markers.Discussion: Previous studies of Cancer/testis-X antigens in breast have focused on ER positive cancers, in smaller subsets and provided inconclusive results. Using comprehensive gene expression data sets and tissue microarrays, we have demonstrated a significant association of MAGEA family and NY-ESO-1/CTAG1B with ER/PR negative breast cancer. Since these cancers represent a subgroup for which less therapeutic modalities are available, we propose the use of MAGEA and NY-ESO-1/CTAG1B cancer vaccines in the adjuvant setting as an approach to restricting tumor growth and metastases. Clinical trails using MAGEA and NY-ESO-1/CTAG1B are warranted.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3139.

Phase I/II study of arginine deiminase (ADI-PEG 20) in patients with advanced malignant melanoma (MM)

9030

Background: ADI-PEG 20 is an enzyme that degrades arginine, a crucial amino acid central to metabolism and biosynthesis of growth and development of normal and neoplastic cells. Melanoma is auxotrophic for arginine because it lacks argininosuccinate synthetase (ASS), a key enzyme required for synthesis of arginine from citrulline via the urea cycle. This study evaluates the safety and clinical efficacy of ADI-PEG 20 in patients with MM. Methods: Patients with histologically confirmed stage III (unresectable)/ IV cutaneous, uveal or mucosal MM were treated with 40, 80 or 160 IU/m2 ADI-PEG 20 i.m. weekly for 9 weeks in a phase I setting. In a phase II component, 16–25 pts receiving 160 IU/m2 will be evaluated for tumor response (TR) by RECIST. Secondary endpoints for all patients included metabolic response by 18FDG-PET, pharmacodynamics (PD), immunogenicity and ASS tumor expression by immunohistochemistry. Results: As of Nov. 2008, 24 pts were enrolled (40 IU/m2, n=6, 80 IU/m2, n=6, 160 IU/m2, n=12): 14 males, 10 females. Median age: 66 yrs (range 29- 83 yrs). Toxicity consisted primarily of Grade 1/2 adverse events (AE) (injection site pain, myalgia, arthralgia, fatigue, flushing, rash/itch, nausea, diarrhea, hyperuricemia, taste alteration). One dose limiting toxicity (DLT) of G3 arthralgia was observed at 80 IU/m2. Two DLTs (G3 seizure and G3 lymphedema) were reported, at 160 IU/m2. No grade 4 or 5 AEs were observed. Of 22 patients evaluable for TR, 8 had stable disease (SD) with 2 of these durable for ≥ 6 months. Notably, 3 SD were uveal melanoma. 14 patients had progressive disease. PD analysis showed plasma arginine depletion during study weeks 1–6 regardless of dose. Immunohistochemical ASS expression analysis in tumor tissue: negative= 13 pts, < 5% cells positive= 5 pts. Conclusions: ADI-PEG 20 as a single agent is well tolerated in advanced MM leading to consistent arginine depletion. The extent of clinical activity has yet to be shown. Combination therapy of ADI-PEG20 with other treatments such as pro-apoptotic reagents during the first 6 weeks of ADI-PEG 20 treatment while arginine is depleted could lead to synergistic anti-cancer activity.

No significant financial relationships to disclose.

Comparison of the immunogenicity of Montanide ISA 51 adjuvant and cytokine-matured dendritic cells in a randomized controlled clinical trial of melanoma vaccines

3002

Background: Dendritic cell (DC) vaccines have been widely used in clinical trials to treat cancer. However, no study has compared the immunogenicity of the most commonly used DC type (cytokine-matured, monocyte-derived DCs) to more traditional vaccine adjuvants. We performed a randomized controlled trial comparing the immunogenicity of cytokine-matured DCs loaded with 6 HLA-A2-restricted peptide antigens and a foreign protein, KLH, to a vaccine containing the same antigens emulsified in the mineral oil adjuvant Montanide ISA 51 VG. Methods: 51 HLA-A2+ patients with resected stage IIb-IIIc melanoma were randomized to receive DCs (25 patients) or Montanide (26 patients). DCs were differentiated from autologous blood monocytes with IL-4 and GM-CSF, then matured with IL- 1β, IL-6, TNFα and PGE2. 18 million DCs were given i.d. every 4 weeks x 4, and immune responses analyzed (MHC multimers, T cell proliferation, cytokine secretion, antibodies). A 3-fold increase over baseline was considered a response. Results: Both vaccines were well tolerated. Immunogenicity was significantly greater with Montanide, as demonstrated by response rates to Flu, Melan-A and NY-ESO-1 peptides by IFNγ ELISPOT. Similar results were obtained by MHC multimer staining, with higher response rates seen using pre-sensitized assays. T cell proliferation to KLH was seen in both arms (90% DC, 100% Montanide), but the magnitude of response was significantly higher for Montanide (36-fold vs. 14-fold increase over baseline, p=0.002, Wilcoxon). KLH-specific CD4+ T cells that produced IFNγ, TNFα and IL-2 were seen only with Montanide, and all Montanide patients, but only 5% of DC patients, developed antibodies to KLH (p<0.001, Fisher's). Conclusions: A water-in-oil vaccine adjuvant, Montanide ISA 51, was significantly more immunogenic than DCs. Future studies of new DC vaccines should compare DCs to standard adjuvants to determine if their added difficulty and expense are truly warranted.

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Phase I trial of huA33 antibody plus 5-fluorouracil (5FU), leucovorin, and oxaliplatin in patients with metastatic colorectal cancer [LUD2003–005]

3022

Background: The selective targeting of tumors with monoclonal antibodies (mAb) has emerged as a new therapeutic approach in cancer therapy with the A33 glycoprotein being a promising target in colorectal cancer. Specific tumor localization and low toxicity of a humanised A33 specific mAb (huA33) has previously been demonstrated in patients with colorectal carcinoma. In the present study, we determined the safety and efficacy of the combination of huA33 and 5FU plus leucovorin and oxaliplatin (FOLFOX-4) in patients with metastatic colorectal cancer. Methods: Patients had to present with metastatic colorectal cancer with an expected survival of at least 4 months and no more than 2 different pre-treatment regimens. Patients were excluded if they had previously received oxaliplatin or huA33 mAb. Eligible patients received huA33 (10 mg/m2) by iv infusion weekly for 12 weeks (cycle 1). On study day 15, standard FOLFOX-4 chemotherapy was administered every 2 weeks for 10 weeks. Responding patients received a second cycle of weekly huA33 (10 mg/m2) and biweekly FOLFOX-4 chemotherapy. Results: A total of 19 patients (11 female, 8 male) with a median age of 60 years entered the study. 5 patients had received prior chemotherapy, 2 radiation therapy and 18 surgery. Toxicities observed were as expected for FOLFOX-4 treatment alone with hematological side effects to be most prominent and included (only G3 and G4) 1 anemia and 10 neutropenias. The addition of huA33 to FOLFOX-4 did not change the pattern of known non-hematological toxicities with a low rate (14%) of huA33 mAb associated allergic reactions. One sudden death occurred at cycle five that was neither therapy nor disease related. Within the 16 patients currently available for response assessment, the overall response rate was 38% with 1 CR, 5 PR and 5 disease stabilizations. Conclusion: The combination of FOLFOX-4 as standard chemotherapy for this cohort of patients in combination with the humanized A33 antibody did not increase toxicities and was well tolerated. The overall response rate of 38% is in the response range published so far for the FOLFOX-4 regimen in this setting and warrants further analysis in a larger cohort of patients.

[Table: see text]

SOX2 antibody responses in patients with various tumor types and SCLC with and without paraneoplastic neurologic syndromes

2562

Background: SOX2, a member of the SOX Group B family of transcription factors, is expressed in normal adult brain, testis and prostate as well as in many SCLC cell lines. Spontaneous antibody responses to SOX2 have previously been shown to be detectable in SCLC patients. We undertook a retrospective study to determine whether antibody responses were detectable in patients with other malignancies and in patients with paraneoplastic neurologic syndromes (PND/PNS). Methods: Previously obtained serum samples from patients with no known disease (n = 84), breast and ovarian cancer (n = 35 each), melanoma (n = 42), NSCLC (n = 150), and SCLC patients, 90 from Turkey and 68 patients studied for PND, were tested by ELISA using serial 4-fold dilutions for anti-SOX2 and anti-HuD antibody. Results: Preliminary data shows SOX2 reactivity in 5/84 (6%) normal volunteer sera, 8/35 (23%) in both breast and ovarian cancer patients, 4/42 (9%) melanoma patients, 20/150 (13.3%) NSCLC patients, and 56/158 (35.4%) SCLC patients. Compared to controls, there was a statistically significant difference in SOX2 immunoreactivity in breast, ovarian (p = 0.007 for both) and SCLC patients (p < 0.001), and a trend was noted in NSCLC patients (p = 0.080). No breast, ovarian, melanoma or normal patient had SOX2 antibody titers ≥1:6400, compared with 32/56 (57.1%) of SCLC (p < 0.01) and 6/20 (30%) NSCLC patients (p < 0.16). Nine SCLC patients had neurologic symptoms and were previously found to have anti-HuD antibodies, associated with a diagnosis of PND. This was confirmed in 8/9 patients in our assay. However, none of the nine patients displayed anti-SOX2 reactivity. Eleven additional SCLC patients were found to be HuD positive by our ELISA. Conclusions: Anti-SOX2 responses are found in a significant proportion of patients with SCLC, breast and ovarian cancer, but not in melanoma patients compared to normal controls. Patients with SCLC have higher titer antibodies when compared with the other groups, and anti-SOX2 antibodies do not appear to associate with anti-HuD responses, supporting the hypothesis that SOX2 immune responses are not associated with PND and may be useful as a vaccine target. Supported by the Cancer and Leukemia Group B/Aventis Oncology Award and the Steps for Breath Foundation.

No significant financial relationships to disclose.

CD8+ tumor-infiltrating lymphocytes as a statistically significant marker of disease recurrence and survival in transitional cell carcinoma patients

4544

Background: Superficial transitional cell carcinoma (TCC) is an immune-responsive tumor evidenced by immunotherapy trials with BCG demonstrating improved survival. In contrast, more advanced muscle-invasive TCC is not considered an immunologically active tumor. Yet, host immune functions that may have a clinical impact on the biologic activity of these more invasive tumors have not been systemically evaluated. CD8+ T-cells are responsible for cytotoxicity and potential tumor eradication by interaction with antigen plus human leukocyte antigens (HLA). A clear association between intratumoral CD8+ T-cells and clinical outcome has not been established in TCC. Methods: We performed pathological, immunohistochemical and RT-PCR analyses of 69 TCC patient samples that were obtained with appropriate informed consent on an Institutional Review Board (IRB)-approved protocol. The samples were studied for pathological stage, tumor-associated antigen expression, class I HLA expression, and CD8+ intratumoral T-cells. Systemic CD8+ T-cells from one patient with positive CD8+ intratumoral T-cells were studied by tetramer analyses for reactivity against the NY-ESO-1 tumor antigen expressed on the patient’s tumor. Results: In a subset analysis, advanced TCC (pT2, pT3 and pT4) patients who had higher numbers of CD8+ tumor infiltrating lymphocytes (TILs) had a greater disease-free survival (p = 0.0002) and overall survival (p = 0.011) than similarly staged TCC patients with lower numbers of CD8+ TILs. In the multivariate analyses, CD8+ TILs (p = 0.04) and tumor stage (p < 0.001) were significant risk factors to predict overall survival. Furthermore, a CD8+ T-cell clone derived from one patient demonstrated strong recognition of the tumor antigen NY-ESO-1. Conclusions: This is the first report, to our knowledge, that CD8+ TILs is an important prognostic indicator for patients with advanced TCC. Investigational immunotherapy strategies to evoke CD8+ T-cell responses are warranted in patients with advanced TCC.

[Table: see text]

In vitro detection of occult bone marrow metastases in patients with colorectal cancer hepatic metastases

PURPOSE

The purpose of this study was to assess the immunocytochemical status of bone marrow aspirates from patients with clinically isolated hepatic metastases to test the hypothesis that such findings would allow improved patient selection for liver-directed treatment.

METHODS

All patients had biopsy-proven or presumed colorectal cancer metastatic to the liver and were scheduled for an operative procedure for hepatic resection or for hepatic artery catheter and chemotherapy pump implant. Immunocytochemical analysis of bone marrow aspirate smears was performed with a panel of monoclonal antibodies directed toward cytokeratins, Lewis Y antigen and A-33 colorectal epitopes.

RESULTS

Data from 80 patients indicated that bone marrow reactivity was present in 9.5 percent of those with resectable hepatic metastases and in 34 percent of those not resected (P = 0.03). No single monoclonal antibody or combination produced better discrimination.

CONCLUSIONS

Presence or absence of presumed occult colorectal cancer cells in the bone marrow of patients with isolated hepatic metastases is biologically interesting, but not useful in selecting or altering patient management.

TNF is a potent anti-inflammatory cytokine in autoimmune-mediated demyelination

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) characterized by localized areas of demyelination. Although the etiology and pathogenesis of MS remain largely unknown, it is generally assumed that immune responses to myelin antigens contribute to the disease process. The exact sequence of events, as well as the molecular mediators that lead to myelin destruction, is yet to be defined. As a potent mediator of inflammation, the cytopathic cytokine, tumor necrosis factor (TNF) has been considered to be a strong candidate in the pathogenesis of MS and its animal model, experimental autoimmune encephalomyelitis (EAE). However, its role in immune-mediated demyelination remains to be elucidated. To determine the contribution of TNF to the pathogenesis of the MS-like disease provoked by the myelin oligodendrocyte glycoprotein (MOG), we have tested mice with an homologous disruption of the gene encoding TNF. Here we report that upon immunization with MOG, mice lacking TNF develop severe neurological impairment with high mortality and extensive inflammation and demyelination. We show further that inactivation of the TNF gene converts MOG-resistant mice to a state of high susceptibility. Furthermore, treatment with TNF dramatically reduces disease severity in both TNF-/- mice and in other TNF+/+ mice highly susceptible to the MOG-induced disease. These findings indicate that TNF is not essential for the induction and expression of inflammatory and demyelinating lesions, and that it may limit the extent and duration of severe CNS pathology.

Frameshift and nonsense p53 mutations in squamous-cell carcinoma of head and neck - non-reactivity with 3 anti-p53 monoclonal-antibodies

p53 mutations in human tumors are often associated with overexpression of p53, and immunohistochemical detection of p53 has frequently been chosen as a simpler method than genetic analysis to access p53 mutations. In this study, we analyzed the p53 gene by single-strand conformational polymorphism (SSCP) and DNA sequencing, and correlated findings to Ab staining results. In a series of 58 squamous cell carcinoma, 15 showed mutations in exons 5, 6, 7, 8 and 9 by SSCP. Of these 15 cases, 11 were positive by antibody staining, and DNA sequencing showed missense mutations but no frameshift or nonsense mutations. In contrast, the antibody-negative cases had frameshift or nonsense mutations, but no missense mutations. SSCP analysis of these 4 cases showed mutations in exon 6 (2 cases), exon 7 (1), and exon 8 (1), respectively. In case 1, sequencing data revealed a single-base addition in exon 6, leading to a truncated gene product of 207 amino acids (aa), in contrast to 393 aa in wild-type p53. Similar frameshift mutations were shown in case 2 and case 3. Case 4, instead of a frameshift mutation, carried a nonsense mutation, and a truncated peptide of 235 aa. All these mutations thus shared the feature of producing truncated p53 products nonreactive with antibodies. We conclude that frameshift mutations as well as nonsense mutations can lead to altered p53 undetectable by available monoclonal antibodies. Our finding indicates that the absence of Ab reactivity does not rule out genetic alterations of the p53 gene in human tumors.

Transfection and expression of a gene coding for a human melanoma antigen recognized by autologous cytolytic T lymphocytes

Human melanoma line MZ2-MEL expresses several antigens recognized by autologous cytolytic T lymphocytes (CTL). As a first step towards the cloning of the gene coding for one of these antigens, we tried to obtain transfectants expressing the antigen. The DNA recipient cell was a variant of MZ2-MEL which had been selected with a CTL clone for the loss of antigen E. It was cotransfected with genomic DNA of the original melanoma line and with selective plasmid pSVtkneo beta. Geneticin-resistant transfectants were obtained at a frequency of 2 x 10(-4). These transfectants were then screened for their ability to stimulate the production of tumor necrosis factor by the anti-E CTL clone. One transfectant expressing antigen E was identified among 70,000 drug-resistant transfectants. Its sensitivity to lysis by the anti-E CTL was equal to that of the original melanoma cell line. When this transfectant was submitted to immunoselection with the anti-E CTL clone, the resulting antigen-loss variants were found to have lost several of the transfected pSVtkneo beta sequences. This indicated that the gene coding for the antigen had been integrated in the vicinity of pSVtkneo beta sequences, as expected for cotransfected DNA.

The influence of cimetidine versus ranitidine on doxepin pharmacokinetics

The effect of cimetidine and ranitidine on doxepin pharmacokinetics was studied in 6 healthy volunteers. Each subject completed 3 study phases: Treatment A, 9 consecutive doses of 50 mg doxepin (once daily); Treatment B, same as Treatment A but co-administration of cimetidine 600 mg b.i.d. starting after the sixth doxepin dose and continuing until approximately 2 days following discontinuation of doxepin administration; Treatment C, identical to Treatment B but with ranitidine 150 mg b.i.d. instead of cimetidine. Unlike ranitidine, cimetidine co-administration resulted in a significant increase in steady state plasma levels of doxepin (4.7, 9.0 and 4.5 ng/ml during Treatments A, B and C respectively) but not desmethyldoxepin (4.1, 4.6 and 4.2 ng/ml during Treatments A, B and C respectively). Elimination half-lives of doxepin and desmethyldoxepin were prolonged by cimetidine co-administration (19.6 and 26.2 h respectively), but remained unchanged during the ranitidine treatment phase (13.3 and 18.4 h) as compared to the control phase i.e. Treatment A (13.2 and 19.0 h). These results show that cimetidine, unlike ranitidine, significantly inhibits the biotransformation of doxepin. This data has clinical implications when the co-administration of tricylic antidepressants and H2-receptor antagonists are indicated.

Cholecystohepatic duct

Review of embryologic and surgical literature emphasizes the great variability in biliary ducts. Major cholecystohepatic ducts are rare, although accessory bile ducts are common. A rare case of intrahepatic junction of right and left hepatic ducts providing drainage through a single cholecystohepatic duct is presented. Chlolecystectomy and primary anastomosis of hepatic ducts and duodenum was successful. We know of no report of a precisely similar case. Awareness of the possibility of these anomalies should increase their reported incidence and decrease the severe morbidity and mortality attending failure of recognition.

Cytochrome c oxidation by the electron transport fraction of Azotobacter vinelandii

The spectrophotometric oxidation of horse heart ferrocytochrome c was examined by use of the particulate electron transport fraction (R(3)) of Azotobacter vinelandii strain O. Unlike cytochrome c, purified preparations of native Azotobacter cytochromes c(4) + c(5) were oxidized only slowly by the electron transport fraction. The oxidation of mammalian cytochrome c proceeded at an appreciable rate and displayed "apparent" first-order kinetics at a pH optimum of 9.0 with tris(hydroxymethyl)aminomethane-chloride buffer. The calculated V(max) value was 0.22 mumole of cytochrome c oxidized per min per mg of protein (25 C) and a K(m) value for cytochrome c of 2.3 x 10(-5)m was obtained. Ferricytochrome c was a "strict" competitive inhibitor for this oxidation. Cytochrome c oxidation by the Azotobacter electron transport system was markedly sensitive to cyanide, azide, and hydroxylamine, although carbon monoxide inhibition could not be demonstrated. It was sensitive also to high concentrations of phosphate, ethylenediaminetetraacetate, and some metal cations. "Aging" or prolonged storage of the Azotobacter R(3) fraction, at 4 C for 10 days, resulted in a threefold increase in specific activity. The cytochrome c peroxidase type of reaction did not occur with the R(3) electron transport fraction.

Enzymatic oxidation of tetramethyl-p-phenylenediamine and p-phenylenediamine by the electron transport particulate fraction of Azotobacter vinelandii

The ability of the electron transport particulate fraction of Azotobacter vinelandii strain O to oxidize tetramethyl-p-phenylenediamine (TMPD) and p-phenylenediamine (PPD) was examined in detail. The highest specific activity for TMPD and PPD oxidation concentrated in the A. vinelandii O R(3) fraction. The A. vinelandii O R(3) fraction was used to develop a standard manometric assay which gave optimal oxidation rates for both of these dyes. The conditions of the assay and all essential related enzymatic kinetic parameters are presented. Other para derivatives of phenylenediamines also were oxidized readily, whereas ortho and meta derivatives were not. Hydroquinone, p-hydroxybenzoic acid, p-cresol, tyrosine, pyrogallol, pyrocatechol, and diphenylamine were not able to serve as electron donors for the A. vinelandii O R(3) system. The probable involvement of a particle-bound cytochrome oxidase is indicated by the marked sensitivity of both TMPD and PPD oxidation to cyanide, axide, phenylhydrazine, hydroxylamine, and, to a lesser degree, carbon monoxide.