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J Schlom

Publications and source records attributed to J Schlom.

At least 19 recordsLinked to original sources
PubMed1992

Immunogenicity and safety of a recombinant vaccinia virus vaccine expressing the carcinoembryonic antigen gene in a nonhuman primate.

We have previously reported the development of a recombinant vaccinia virus vaccine expressing the human carcinoembryonic antigen (CEA) gene, designated rV(NYC)-CEA. This construct has been shown to elicit specific anti-CEA immune responses and an antitumor effect in a murine tumor model. In the studies reported here, the safety and immunogenicity of this recombinant vaccinia virus were evaluated in a rhesus monkey model. Human CEA is a M(r) 180,000 glycoprotein expressed in approximately 90% of gastrointestinal carcinomas and in some breast and non-small cell lung carcinomas. This family also includes normal cross-reacting antigen (NCA). Rhesus monkeys, like humans, have some NCA on the surface of their granulocytes. Eight monkeys were immunized 3 or 4 times by skin scarification with the recombinant CEA vaccine and four monkeys received wild-type vaccinia virus as control. After three vaccinations, all rV(NYC)-CEA-vaccinated animals exhibited a strong anti-CEA antibody response as measured by enzyme-linked immunosorbent assay. The functional ability of these antibodies to mediate lysis of a CEA-bearing tumor cell was demonstrated using human effector cells. This response could be enhanced by interleukin 2. Cellular immunity to CEA was measured by delayed-type hypersensitivity upon intradermal challenge with purified CEA. Only those animals receiving the recombinant vaccine displayed significant anti-CEA responses. Furthermore, peripheral blood mononuclear cells from immunized monkeys were found to proliferate in response to CEA stimulation. All vaccinated monkeys developed local skin irritation at the site of the vaccination, regional lymphadenopathy, and low-grade fevers after immunization. Following immunization with rV(NYC)-CEA, the response was consistent with the usual constitutional symptoms seen with human smallpox virus immunization. Blood counts, differentials, and hepatic and renal chemistries remained normal in all animals throughout the study and for up to 1 year following the primary vaccination. No evidence of immunological cross-reactivity to NCA was found by either a fall in the granulocyte count or analyses for anti-NCA antibodies. Thus, the rV(NYC)-CEA vaccine appears to be safe in rhesus monkeys. The administration of a CEA recombinant vaccine to rhesus monkeys induces both a humoral and a cell-mediated immune response directed against human CEA.

Animals↗
PubMed1992

Differential metabolic patterns of iodinated versus radiometal chelated anticarcinoma single-chain Fv molecules.

Genetically engineered single-chain Fvs (sFv) are defined as recombinant proteins composed of a variable light chain amino acid sequence of an immunoglobulin tethered to a variable heavy chain sequence by a designed peptide. Previous studies using iodine-labeled sFv, derived from the anticarcinoma monoclonal antibody CC49, showed that the 125I-sFv could efficiently target antigen-positive tumors in a human tumor xenograft model while demonstrating rapid plasma clearance and minimal uptake in normal organs. One of the issues we raised in the analysis of the iodinated sFv metabolic studies was whether similar metabolic patterns would be observed if the sFv were labeled with a radiometal. In the studies reported here, 125I-CC49 sFv and 177Lu-CC49 sFv were co-injected in mice bearing antigen-positive carcinoma xenografts. Both sFv forms showed similar tumor targeting and plasma clearance pharmacokinetics. The 177Lu-sFv, however, showed a greater uptake in liver and spleen and a much higher uptake in kidney. These studies thus demonstrate that despite their small size (M(r) 27,000), the metal-chelated sFv shows a metabolic pattern very different than that of the iodinated sFv, which is most likely due to retention of the metal by organs metabolizing the sFv.

Animals↗
PubMed1992

Antitumor activity and immune responses induced by a recombinant carcinoembryonic antigen-vaccinia virus vaccine.

BACKGROUND: Human carcinoembryonic antigen (CEA) is a 180-kd glycoprotein expressed in human colorectal, gastric, pancreatic, breast, and non-small-cell lung carcinomas. Previous studies have demonstrated enhanced immune responses to other antigens presented with vaccinia virus proteins via a recombinant vaccinia virus construct. In addition, we have developed a recombinant CEA-vaccinia virus construct, designated rV(WR)-CEA, and have demonstrated humoral anti-CEA responses in mice after immunization with that virus. PURPOSE: The goals of this study were (a) to construct a recombinant CEA-vaccinia vaccine in a less virulent vaccinia strain that is potentially safe and effective for treatment of patients whose tumors express CEA and (b) to evaluate the ability of the recombinant CEA-vaccinia vaccine to prevent and reverse tumor growth in mice and to elicit cell-mediated and humoral anti-CEA immune responses. METHODS: Using the New York City strain of vaccinia virus, which is used in smallpox vaccination and is more attenuated for humans than rV(WR), we derived a recombinant CEA-vaccinia construct, designated rV(NYC)-CEA. The ability of this construct to induce antitumor immunity was evaluated in mice receiving subcutaneous injections of murine colon adenocarcinoma cells expressing the human CEA gene. RESULTS: Administration of rV(NYC)-CEA in mice induced strong anti-CEA antibody responses, as well as CEA-specific cell-mediated responses, including delayed-type hypersensitivity, lymphoproliferative, and cytotoxic responses. Vaccination of mice with the rV(NYC)-CEA rendered them resistant to the growth of subsequently transplanted CEA-expressing tumors. Moreover, when mice were vaccinated 7 days after tumor cell injection, tumor growth was either greatly reduced or eliminated. No toxic effects were observed in any of the mice. CONCLUSION: These studies demonstrate that antitumor activity can be induced with the use of a recombinant CEA-vaccinia virus construct derived from an attenuated vaccinia strain, and they reveal the range of cell-mediated and humoral responses induced by this recombinant vaccine.

Adenocarcinoma↗
PubMed1992

Rapid tumor penetration of a single-chain Fv and comparison with other immunoglobulin forms.

Single-chain antigen-binding proteins, or sFvs, represent potentially unique molecules for targeted delivery of drugs, toxins, or radionuclides to a tumor site. In previous studies (Cancer Res., 51:6363-6371, 1991) using a human colon carcinoma xenograft model, it was demonstrated that the sFv has an extremely rapid plasma and whole body clearance, as compared to intact IgG or Ig fragments. One potential consequence of the rapid sFv pharmacokinetic properties was the reduced percentage of injected dose/g of the radiolabeled sFv found in the tumor throughout a range of time points. The present study was designed to define the tumor penetration properties of a radiolabeled sFv in comparison with other Ig forms. 125I-labeled sFv, Fab', F(ab')2, and IgG forms of monoclonal antibody CC49, directed against the human pancarcinoma antigen TAG-72, were used to target the LS-174T human colon carcinoma xenograft in athymic mice. At various time points after systemic Ig administration, quantitative autoradiographic analyses of surgically removed tumors were used to define the rate and degree of penetration of the various Ig forms. These studies revealed that most of the intact IgG delivered to the tumor was concentrated in the region of or immediately adjacent to vessels, while the sFv was more evenly distributed throughout the tumor mass. The distributions of the Fab' and F(ab')2 fragments showed intermediate penetration in a size-related manner. The sFv demonstrated maximum tumor penetration at 0.5 h postinjection, while the intact IgG reached an equivalent degree of penetration at 48 to 96 h postinjection. These studies thus reveal a greater degree of uptake throughout the tumor for the sFv than would be expected by gross analyses of percentage injected dose/g and demonstrate an extremely rapid tumor penetration of the sFv. These studies should aid in the rational design of potential applications of drug-, toxin-, and radionuclide-conjugated sFvs in cancer therapy.

Animals↗
PubMed1992

Therapeutic advantage of high-affinity anticarcinoma radioimmunoconjugates.

The effect of the relative affinity (Ka) on the antitumor efficacy of monoclonal antibodies (MAbs) has been questioned. It has previously been shown in experimental models that the use of MAbs with higher relative Kas manifests itself in a higher percentage of injected dose of MAb bound to tumor. On the other hand, mathematical models have proposed that the use of higher affinity MAbs may be disadvantageous for antitumor effects, since higher Ka MAbs would bind more antigen and prevent penetration of MAb through tumor. To test this hypothesis, three MAbs reacting to the human pancarcinoma antigen TAG-72 were used as radioimmunoconjugates for therapeutic efficacy versus the LS-174T human colon carcinoma xenograft. MAbs B72.3, CC49, and CC83 have all been shown by depletion studies to react to the same molecule and to all react with overlapping epitopes. While the relative Ka of B72.3 is 2.5 x 10(9) M-1, the relative Kas of CC49 and CC83 are 16.2 and 27.7 x 10(9) M-1, respectively. Each MAb was radiolabeled with 131I, and each radioimmunoconjugate was assayed at five dose levels for therapeutic efficacy using the human xenograft model. The results of these studies demonstrate substantial therapeutic advantage of the higher affinity MAbs CC49 and CC83 versus B72.3 at every dose level. While 500 microCi of B72.3 were required to reduce tumor growth in only a minority of tumor-bearing animals, the use of the same amount or less of the radioimmunoconjugates of CC49 or CC83 resulted in strong antitumor effects in 80 to 100% of tumor-bearing animals. Thus, stronger antitumor effects were seen using as little as 2.5- to 3-fold less of the higher Ka immunoconjugates CC49 and CC83 as compared with B72.3. While we acknowledge the potential disadvantages of higher Ka MAbs in some situations, at least the experimental studies and model system described here show that a distinct therapeutic advantage exists with the use of higher affinity immunoconjugates.

Adenocarcinoma, Mucinous↗
PubMed1992

Interleukin-6 increases carcinoembryonic antigen and histocompatibility leukocyte antigen expression on the surface of human colorectal carcinoma cells.

Human colorectal carcinoma cells that were treated in vitro with interleukin-6 (IL-6) expressed increased levels of carcinoembryonic antigen (CEA) and normal histocompatibility leukocyte antigen (HLA) class I on their cell surface. The IL-6 mediated increase of CEA expression on the surface of a moderately differentiated colon carcinoma cell line (WiDr) was time- and dose-dependent. A 5-day treatment of the WiDr cells with 100 U IL-6/ml increased the percentage of cells that expressed CEA from 29 to > 80% and enhanced the level of HLA class I expression. The increase in CEA expression as a result of IL-6 treatment was also observed using SDS-PAGE/Western blot analyses, and subsequent Northern blot analyses revealed concomitant increases in CEA-related mRNA transcripts. A comparison of the increases in CEA expression after IL-6, interferon-beta, and interferon-gamma on a nanomolar basis revealed that IL-6 was more potent than either of the interferons. Of 11 different human colorectal tumor cell lines that were treated with IL-6, CEA and/or HLA class I expression were increased in five. Thus, IL-6 can act directly on human colon carcinoma cells and selectively increase the expression of CEA and HLA class I antigens, which may provide some insight into the mechanisms involved in the ability of IL-6 to suppress in vivo tumor growth.

Antigens, Neoplasm↗
PubMed1992

Intraperitoneal administration of interferon-gamma to carcinoma patients enhances expression of tumor-associated glycoprotein-72 and carcinoembryonic antigen on malignant ascites cells.

PURPOSE: The study was designed to determine whether in vivo interferon gamma (IFN-gamma) administration could enhance tumor antigen expression on the surface of human tumor cells. MATERIALS AND METHODS: Eight patients (six with ovarian and two with gastrointestinal tumors) with a diagnosis of adenocarcinoma with secondary malignant ascites were given weekly escalating doses of IFN-gamma (ie, 0.1 to 100 MU) intraperitoneally (IP) each week for 8 weeks. Tumor cells were isolated from the patients' ascites samples, which were collected three times per week: before and 24 and 48 hours post-IFN-gamma administration. The level of expression of tumor-associated glycoprotein-72 (TAG-72) and carcinoembryonic antigen (CEA) was measured using flow cytometry and immunocytochemistry. RESULTS: IFN-gamma administered IP dramatically increased TAG-72 (as measured by binding of anti-TAG-72 monoclonal antibodies [MoAbs] B72.3 and CC 49) and CEA (measured by MoAb COL-1) expression on the surface of the carcinoma cells. The ascites-derived tumor cells from seven of the eight patients constitutively expressed TAG-72, and the level of TAG-72 expression was increased by IFN-gamma in all seven patients, as evidenced by the enhanced binding of anti-TAG-72 MoAbs to the tumor-cell surface. In some cases, IFN-gamma treatment increased the percentage of MoAb B72.3-reactive tumor cells from 10% to greater than 90%, and those changes were further corroborated by similar increases in the MoAb staining intensity observed with immunoperoxidase analysis. In addition, ascites-derived tumor cells from two patients with gastrointestinal carcinoma also expressed enhanced CEA levels after IFN-gamma. The increased TAG-72 and CEA expression were observed at low IFN-gamma doses (ie, 0.1 to 1.0 MU), which were well tolerated by all patients. CONCLUSIONS: The ability of IFN-gamma given IP to increase TAG-72 and CEA expression on tumor cells in vivo provides additional argument for the use of the cytokine as an adjuvant to enhance MoAb binding to human carcinoma-cell populations.

Antigens, Neoplasm↗
PubMed1992

Dose fractionation of radiolabeled antibodies in patients with metastatic colon cancer.

Twelve patients with metastatic colon cancer were treated with 131I-chimeric B72.3 (IgG-4) at total doses of 28 or 36 mCi/m2 in two or three weekly fractions. Bone marrow suppression was the only significant side effect. The degree of bone marrow suppression adjusted for whole-body dose was modestly but statistically significantly (p = 0.04) less than that seen with identical doses given as a single infusion for the total dose of 36 mCi/m2. Nine of twelve patients developed an antibody response to ch B72.3, which altered the kinetics of radiolabeled antibody in four patients given a second course of therapy. One patient had a minor response that lasted 4 mo. Fractionation of this particular radiolabeled antibody at the dose schedule used produced a modest increase in the therapeutic window in regard to administered dose.

Adult↗
PubMed1979

Characterization of a retrovirus isolated from normal mink cells co-cultivated with a dog mammary tumour.

A retrovirus antigenically distinct from known type C, B and D viruses was isolated from normal mink (Mustela vison) lung cells that had been co-cultivated with 5-iododeoxyuridine- and dexamethasone-treated dog mammary tumour cells. Cytogenetic studies of the virus-releasing co-culture showed mitotic figures identical to the normal mink cell line (MvlLu) with the exception of a low frequency of cells with extensive chromosomal breakage and uncoiling. The new virus bands at a buoyant density of 1.16 g/ml, contains 60S RNA and a reverse transcriptase which prefers Mn2+ over Mg2+ for the synthesis of DNA. This enzyme utilizes poly(rA).oligo(dT) more efficiently than poly(dA).oligo(dT) and is also able to synthesize DNA copies from the endogenous RNA. Morphologically, it is a typical type C virus. Filtered virus readily infects mink, dog and other mammalian cells indicating the amphotropic nature of its cell growth requirement. Hybridization studies showed that normal mink DNA contains multiple copies of proviral sequences of this newly isolated virus. Serological analyses indicate that the mink endogenous virus contains in its core protein, in addition to the interspecies type-C determinant, an antigenic component related to one of the determinants found in the feline leukaemia virus p30 protein. This determinant is not present in the Rauscher leukaemia virus, RD114 virus or simian sarcoma virus.

Animals↗
PubMed1979

Diversity of mammary tumor viral genes within the genus Mus, the species Mus musculus, and the strain C3H.

Proviral sequences complementary to the C3H mouse mammary tumor virus RNA genome are present in the DNA of early occurring mammary tumors of C3H/HeN mice and are absent from apparently normal C3H/HeN tissues; these sequences are non-germ line transmitted in C3H/HeN mice and have been termed tumor-associated sequences; (W. Drohan et al., J. Virol. 21:986-995, 1977). We report here that tumor-associated sequences are present in the DNA of spontaneous mammary tumors that occur early in the life of several inbred, high-tumor-incidence mouse strains but are absent in mammary tumors that occur later in life in low- and moderate-tumor-incidence strains. These sequences are also absent in apparently normal organs tested from numerous laboratory mouse strains, feral mice, Mus musculus subspecies, and other Mus species. Sequences represented in tumor-associated sequence RNA, however, are present as endogenous provirus in GR mice (at approximately four copies per haploid genome) and in two of five substrains of C3H mice tested (at approximately one copy per haploid genome). The two substrains of C3H mice positive for endogenous tumor-associated sequence provirus were recently (circa 1930) separated from the negative substrains of C3H mice. The results may be explained by the unlikely chance segregation of proviral sequences or by the recent integration of viral genes (within the last few decades). Whereas radioactively labeled mouse mammary tumor virus 60-70S RNA or complementary DNA detected mouse mammary tumor virus-related proviral information in all laboratory mouse strains, feral mice, subspecies of M. musculus, and other species of Mus, the use of tumor-associated sequence RNA clearly revealed the genetic diversity that may exist between different colonies or substrains of "inbred" laboratory mice commonly used in cancer research.

Animals↗
PubMed1979

Radioimmunoassays for the 36,000-dalton glycoprotein of murine mammary tumor viruses demonstrate type, group, and interspecies determinants.

Mouse mammary tumor viruses (MMTVs) contain distinct membrane glycoproteins of 52,000 daltons (gp52) and 36,000 daltons (gp36). We report here the development of new radioimmunoassays for gp36, using gp36 purified by hydrophobic chromatography and gel filtration. These assays demonstrate that gp36 has both type-specific and group-specific antigenic determinants. The virus-coded nature of these determinants was shown by utilizing different MMTVs grown in the same feline cell line. Interspecies determinants on gp36 were demonstrated by the observations that (i) MC-MTV (a virus isolate from the Asian rodent Mus cervicolor, and morphologically identical to MMTVs) competed, with an altered slope, in the gp36 radioimmunoassay, and (ii) antisera raised against MC-MTV immunopreciptitated 125I-labeled gp36. The detection of gp36 in spontaneous mammary tumors of several strains of mice also facilitates further studies on the replication of MMTVs and the host's immune response to MMTV-mediated oncogenesis.

Animals↗
PubMed1979

Use of molecular hybridization to detect type D retrovirus markers in rhesus placentas and other tissues.

We have shown previously that approximately 20% of the Mason-Pfizer virus (MPV) genome is present as endogenous provirus in rhesus monkeys. We report here that several full-term rhesus placentas examined contain additional MPV proviral sequences in their DNA. Competitive molecular hybridization experiments demonstrated that some of these placentas also contain RNA complementary to the entire MPV 60 to 70S RNA genome. Examination of internal organs of rhesus monkeys captured in the wild also revealed the presence of additional MPV proviral sequences and expression of MPV RNA in some tissues. These results provide further evidence that MPV is being transmitted via a non-germ line mechanism in the rhesus population and now demonstrate the placenta as a good source for the identification of retrovirus transcriptional products and proviral DNA.

Animals↗
PubMed1978

The use of standard and relaxed hybridization conditions to detect two classes of sequences related to type-D retroviruses in the DNAs of primates.

Using standard hybridization conditions (68 degrees C and 0.4 M sodium phosphate) and assaying for RNAase-resistant RNA . DNA duplexes in the presence of 2 X SSC (1 X SSC is 0.15 M NaCl and 0.015 M sodium citrate), sequences representing approx. 20% of the Mason-Pfizer virus (MPV) genome have previously been shown to be endogenous in DNAs of all Old World monkeys examined (Drohan, W., Colcher, D., Schochetman, G. and Schlom, J. (1977) J. Virol. 23, 36--43). We now report that titration of both the temperature at which hybridizations are carried out and the Na+ concentration at which 125I-labeled MPV RNA . DNA hybrids are scored, reveals a second class of sequences related to the MPV genome in the DNAs of primates. These MPV-related sequences, which are similar to an additional 40% of the MPV genome, are detected when the temperature of hybridization is reduced to 54 degrees C and when the resulting 125I-labeled RNA . DNA duplexes are scored for RNAase resistance in 8 X SSC. These sequences are found in the DNAs of all Old World monkeys examined, and the Tm values of the hybrid duplexes are approx. 6--7 degrees C lower than those of the hybrid duplexes formed using standard conditions. These studies further demonstrate the wide distribution of type-D retrovirus sequences in primates.

Animals↗
PubMed1978

Isolation of host-range variants of mouse mammary tumor viruses that efficiently infect cells in vitro.

Host-range variants of mouse mammary tumor virus (MMTV) have been isolated that have the ability to productively infect cells in vitro with high efficiency (at multiplicities of infection </=1) and with extremely short latent periods to the production of de novo virus (as short as 4 days after infection). These variants of the highly oncogenic MMTV of RIII, C3H, and GR mice were obtained by serial virus passage in feline cells. The resultant variant stocks react in group-specific radioimmunoassays for the MMTV major external glycoprotein (gp52) and major internal protein (p28), possess a protein profile similar to that of wild-type MMTV, and contain a virion-associated DNA polymerase with a magnesium cation preference. Addition of dexamethasone and insulin to culture media enhances the titer of de novo MMTV to levels of approximately 10(10) particles per 75-cm(2) flask (containing 5 x 10(6) cells) per 24 hr. Variant stocks exhibit no evidence of contamination with either murine or feline type C retroviruses, as assayed by various techniques. The variants of MMTV derived from C3H and RIII mice exhibit differential host ranges that include the ability to productively infect feline, canine, bat, mink, murine, and human cells. Use of these MMTV host-range variants now facilitates the study of the complete replicative cycle of MMTV as well as an elucidation of the interaction of MMTV with various hormones, physical or chemical carcinogens, and tumor promoters in the initiation and promotion of mammary neoplasia.

Animals↗