Aprepitant versus metoclopramide, both combined with dexamethasone, for the prevention of cisplatin-induced delayed emesis: a randomized, double-blind study.

BACKGROUND: A combination of aprepitant, a 5-HT3 receptor antagonist (r.a.), and dexamethasone is recommended for the prophylaxis of cisplatin-induced nausea and vomiting in the acute phase, and aprepitant + dexamethasone (A + D) in the delayed phase. The aim of this study was to verify if A + D is superior to metoclopramide plus dexamethasone (M + D) in preventing delayed emesis in cancer patients receiving the same prophylaxis for acute emesis. PATIENTS AND METHODS: A randomized double-blind study comparing A + D versus M + D was completed in previously untreated cancer patients. Before chemotherapy, all patients were treated with intravenous palonosetron 0.25 mg and dexamethasone 12 mg, and oral aprepitant 125 mg. On day 2-4, patients randomly received oral dexamethasone 8 mg plus aprepitant 80 mg once daily (days 2-3) or metoclopramide 20 mg four times daily plus dexamethasone 8 mg bid. Primary endpoint was rate of complete response (no vomiting, no rescue treatment) in day 2-5 after chemotherapy. RESULTS: Due to difficulty in the accrual of patients, 303 of the 480 planned patients were enrolled, 284 were fully evaluable, 147 receiving A + D, 137 M + D. Day 1 results were similar in both arms. On day 2-5, complete response rate was not significantly different (80.3% with A + D versus 82.5% with M + D, P < 0.38, respectively), and all secondary endpoints were also similar (complete protection, total control, no vomiting, no nausea, and score of Functional Living Index-Emesis; P < 0.24). Adverse events incidence was not significantly different between the two treatments. CONCLUSIONS: In cancer patients submitted to cisplatin-based chemotherapy, receiving the same antiemetic prophylaxis for acute emesis, A + D is not superior to M + D in preventing delayed emesis, and both treatments present similar toxicity. CLINICALTRIALSGOV NUMBER: NCT00869310.

Inhibition of cytotoxic T cell development by transforming growth factor beta and reversal by recombinant tumor necrosis factor alpha.

The immunoregulatory effects of transforming growth factor beta (TGF-beta) and recombinant murine tumor necrosis factor alpha (rMuTNF-alpha) on CTL generation and activity were examined. The results demonstrate that TGF-beta, in a dose-dependent manner, inhibited CTL generation but not CTL activity. The inhibitory effects were detected only when TGF-beta was added within the first 48 h of the MLC. Little activity was seen when it was added thereafter, including the addition of TGF-beta to the cytotoxicity assay. The production of TNF-alpha, which occurs during early phases of the MLC and which is inhibited in the presence of TGF-beta, appears to have an important regulatory role, as altering the levels of TNF-alpha in an MLC can significantly influence CTL development. The inhibitory effects of TGF-beta on the MLC can be significantly reversed by the addition of rMuTNF-alpha to the cultures. These results demonstrate that TGF-beta can inhibit MLC and subsequent CTL generation at early stages of the reaction, and such inhibition may involve the suppression of TNF-alpha production.

Tumor necrosis factor alpha/cachectin is a growth factor for thymocytes. Synergistic interactions with other cytokines.

Recombinant murine (rm) TNF-alpha but not recombinant human (rh) TNF-alpha induces the proliferation of murine thymocytes in the presence of a comitogenic stimulus. This effect does not appear to be due to the production of significant levels of IL-1, IL-2, or IL-4. although not directly mitogenic (i.e., in the absence of PHA-P) for thymocytes, rmTNF-alpha amplifies the direct mitogenic signals from hIL-1 and rhIL-2 but not rmIL-4. In the presence of PHA-P, thymocytes stimulated with hIL-1, rhIL-2, and rmIL-4 produced significant amounts of TNF-alpha. Although rhTNF-alpha does not induce a proliferative response, it will competitively inhibit the proliferative response of thymocytes to rmTNF-alpha. These data suggest a critical role for TNF-alpha in the intrathymic proliferation of developing T cells.

Immunoregulatory role of transforming growth factor beta (TGF-beta) in development of killer cells: comparison of active and latent TGF-beta 1.

Using recombinant DNA technology, we have generated Chinese hamster ovary (CHO) cell lines that synthesize latent transforming growth factor beta 1 (TGF-beta 1) to study immune regulation by TGF-beta 1. In vitro, latent TGF-beta 1 synthesized by transfectants or added exogenously as a purified complex after activation inhibited CTL generation to a similar extent as seen with acid-activated recombinant human (rHu) TGF-beta 1. In vivo, serum from nu/nu mice bearing CHO/TGF-beta 1 tumors contained significant levels of latent TGF-beta 1 in addition to depressed natural killer (NK) activity in spleens which paralleled that seen in C3H/HeJ mice treated with acid-activated rHuTGF-beta 1. rHuTGF-beta 1 treatment of mice receiving heart allografts resulted in significant enhancement of organ graft survival. Because of possible regulated tissue-specific activation, administration of latent rather than active TGF-beta may provide a better route to deliver this powerful immunosuppressive agent in vivo.

Induction of human IgE synthesis by CD4+ T cell clones. Requirement for interleukin 4 and low molecular weight B cell growth factor.

We have analyzed in detail the precise requirements for the induction of human IgE synthesis using several experimental approaches with purified B cells and well-characterized alloantigen-specific CD4+ T cell clones expressing different profiles of lymphokine secretion. Using these clones under cognate conditions in which the B cells expressed alloantigens recognized by the cloned T cells, we have confirmed that IL-4 is required for the induction of IgE synthesis, but we have clearly demonstrated that IL-4 by itself is not sufficient. With several cloned CD4+ T cell lines, including an IL-4-producing clone that could not induce IgE synthesis, and cloned T cells pretreated with cyclosporin A to inhibit lymphokine synthesis, we showed that Th cell-B cell interactions are necessary for IgE synthesis, and that low molecular weight B cell growth factor (LMW-BCGF) and IL-4, in combination, are lymphokines of major importance in the induction of IgE synthesis. Together our results indicate that optimal induction of an IgE-specific response requires the exposure of B cells to a particular complex of signals that include (a) a signal(s) involving Th-B cell interaction that primes B cells to receive additional signals from soluble lymphokines, (b) a specific B cell proliferative signal provided by LMW-BCGF, and (c) a specific B cell differentiation signal provided by IL-4.

Dendritic cells initiate a two-stage mechanism for T lymphocyte proliferation.

T cells oxidized with sodium periodate proliferate polyclonally in response to accessory cells. We confirmed previous work showing that DC are potent stimulators of this response. In addition, the accessory function of unfractionated mouse spleen and spleen adherent cells was markedly reduced after elimination of DC with a specific monoclonal antibody and complement. Therefore oxidative mitogenesis was used as a model to study the mechanism by which DC stimulate T cell proliferative responses. A two-stage mechanism was identified. The first stage occurred during the first 20 h of culture, required live DC, and involved the progressive release of interleukin 2 (IL-2) into the medium and acquisition of responsiveness to this growth factor. The second stage occurred between 20 and 40 h, did not require live DC, and involved DNA synthesis in response to IL-2. Similar events occurred during culture of DC with unmodified T cells (syngeneic MLR) but were quantitatively reduced. The experimental approach was to co-culture DC and T cells for up to 20 h and then kill the DC with specific antibody, or anti-Ia antibody, and complement. Subsequent proliferation was inhibited if the T cells were cultured in fresh medium. However, proliferation was restored when the lymphocytes were cultured in the original DC-T cell medium, or with a crude or a purified preparation of IL-2. IL-2 did not induce the proliferation of T cells that had been cultured in the absence of DC, and did not synergize with viable DC. We conclude that DC induce proliferation by tightly coordinating the release of, and responsiveness to, T cell growth factor or IL-2.

Epitopes on H-2Dd somatic cell mutants recognized by cytotoxic T cells.

We have generated several cell lines that express an altered H-2Dd molecule. These cell lines, which were selected for by the failure to express the serological specificity reacting with the monoclonal antibody 34-2-12, have also undergone alterations in epitopes recognized by CTL. One of the mutants, 2.12(-4) was not killed by an allogeneic anti-Dd CTL line, CTLL-A2, even though this line was cytotoxic for the parental cell line and two other 34-2-12- mutant lines. Two of the 34-2-12- mutant lines had an identical serological profile using other monoclonal Dd antibodies, however these two mutants differed markedly in their susceptibility to cytotoxicity by CTLL-A2. In addition to the determinants recognized by allogeneic CTL we also examined the effect of the mutation on the determinants involved in restricting the anti-FITC modified-self-cytotoxic response. An anti-FITC-Dd CTL line did not react with two of the mutants and reacted only weakly with the other mutant, demonstrating not only that the Dd epitopes recognized by this cell line and the allogeneic CTL were different, but also that it is possible for a H-2 class I molecule to express epitopes recognized by allogeneic CTL but not epitopes that function as restricting elements to certain antigens. The observation that both T cell- and B cell-defined determinants were altered in these mutant cell lines is in contrast to the findings, with the mutant mouse strains which were selected for by changes in T cell-defined determinants, which show few, if any, alterations to serological specificities. Characterization of T cell-recognized epitopes expressed on serologically selected somatic cell variants may therefore prove to be most useful for the study of structure-function relationships of H-2 class I molecules.

Biological and antigenic similarities of murine interferon-gamma and macrophage-activating factor.

Murine peritoneal exudate cells (PEC) treated with murine recombinant interferon-gamma (IFN-gamma) (greater than 99% estimated purity), or concanavalin A-stimulated spleen cell supernatants developed tumoricidal properties (macrophage activation factor [MAF] activity). MAF activity was found to occur with treatments of 10 U/ml IFN-gamma, and at levels as low as 1 U/ml IFN-gamma if a second signal (5 ng/ml endotoxin) was present in the MAF assay. Endotoxin (lipopolysaccharide [LPS]) alone at these levels failed to induce MAF; induction of MAF was observed at 1,000-fold greater levels. The ability of IFN-gamma to stimulate murine PEC was species specific. Various sources of materials that displayed MAF activity, including supernatants from interleukin 2-dependent cloned cytotoxic murine T lymphocyte lines that did not display detectable antiviral activity, were neutralized by antibody raised and affinity purified against recombinant IFN-gamma. Thus, IFN-gamma, although never detectable by antiviral assays, appears to be present in many lymphokine preparations and has potent macrophage activation capability.

Inhibition of cytokine production by cyclosporin A and transforming growth factor beta.

We investigated the ability of cyclosporin A (CsA) and transforming growth factor beta (TGF-beta) to modulate the production of TNF-alpha and TNF-beta and IFN-gamma by unseparated, nonadherent, and adherent PBMC. Treatment of unseparated PBMC with CsA resulted in a significant dose-dependent inhibition of all three cytokines ranging from greater than 90% inhibition for IFN-gamma and TNF-beta, to approximately 70% for TNF-alpha. Pretreatment of unseparated or nonadherent PBMC with TGF-beta inhibited the production of IFN-gamma by 60-70%. However, the inhibition of TNF-alpha and TNF-beta production by these cells was only minimally affected, and at 0.1-1 ng/ml TGF-beta could enhance TNF-alpha production by unseparated PBMC. In contrast, pretreatment of adherent PBMC with TGF-beta inhibited the production of TNF-alpha by approximately 60%. TGF-beta also inhibited both TNF-alpha production and tumor cell cytotoxicity mediated by murine peritoneal-derived macrophages. These observations indicate that the biological effects of CsA and TGF-beta on immune functions are of a wider range than previously reported.

Tumor necrosis factor (cachectin) is an endogenous pyrogen and induces production of interleukin 1.

Recombinant human tumor necrosis factor (rTNF alpha) injected intravenously into rabbits produces a rapid-onset, monophasic fever indistinguishable from the fever produced by rIL-1. On a weight basis (1 microgram/kg) rTNF alpha and rIL-1 produce the same amount of fever and induce comparable levels of PGE2 in rabbit hypothalamic cells in vitro; like IL-1, TNF fever is blocked by drugs that inhibit cyclooxygenase. At higher doses (10 micrograms/kg) rTNF alpha produces biphasic fevers. The first fever reaches peak elevation 45-55 min after bolus injection and likely represents a direct action on the thermoregulatory center. During the second fever peak (3 h later), a circulating endogenous pyrogen can be shown present using passive transfer of plasma into fresh rabbits. This likely represents the in vivo induction of IL-1. In vitro, rTNF alpha induces the release of IL-1 activity from human mononuclear cells with maximal production observed at 50-100 ng/ml of rTNF alpha. In addition, rTNF alpha and rIFN-gamma have a synergistic effect on IL-1 production. The biological activity of rTNF alpha could be distinguished from IL-1 in three ways: the monophasic pyrogenic activity of rIL-1 was destroyed at 70 degrees C, whereas rTNF alpha remained active; anti-IL-1 neutralized IL-1 but did recognize rTNF alpha or natural cachectin nor neutralize its cytotoxic effect; and unlike IL-1, rTNF alpha was not active in the mitogen-stimulated T cell proliferation assay. The possibility that endotoxin was responsible for rTNF alpha fever and/or the induction of IL-1 was ruled-out in several studies: rTNF alpha produced fever in the endotoxin-resistant C3H/HeJ mice; the IL-1-inducing property of rTNF alpha was destroyed either by heat (70 degrees C) or trypsinization, and was unaffected by polymyxin B; pyrogenic tolerance to daily injections of rTNF alpha did not occur; levels of endotoxin, as determined in the Limulus amebocyte lysate, were below the minimum rabbit pyrogen dose; and these levels of endotoxin were confirmed by gas chromatography/mass spectrometry analysis for the presence of beta-hydroxymyristic acid. Although rTNF alpha is not active in T cell proliferation assays, it may mimic IL-1 in a T cell assay, since high concentrations of rTNF alpha induced IL-1 from epithelial or macrophagic cells in the thymocyte preparations. These studies show that TNF (cachectin) is another endogenous pyrogen which, like IL-1 and IFN-alpha, directly stimulate hypothalamic PGE2 synthesis. In addition, rTNF alpha is an endogenous inducer of IL-1.(ABSTRACT TRUNCATED AT 400 WORDS)

Mediation of cardioprotection by transforming growth factor-beta.

Myocardial ischemia causes heart injury that is characterized by an increase in circulating tumor necrosis factor (TNF), the local production of superoxide anions, the loss of coronary vasodilation (relaxation) in response to agents that release endothelial cell relaxation factor, and cardiac tissue damage. Ischemic injury can be mimicked by TNF. When given before or immediately after ischemic injury, transforming growth factor-beta (TGF-beta) reduced the amount of superoxide anions in the coronary circulation, maintained endothelial-dependent coronary relaxation, and reduced injury mediated by exogenous TNF. Thus, TGF-beta prevented severe cardiac injury, perhaps by alleviating damage mediated by increases in circulating TNF.

Recombinant human tumor necrosis factor-alpha: effects on proliferation of normal and transformed cells in vitro.

Modulation of the growth of human and murine cell lines in vitro by recombinant human tumor necrosis factor-alpha (rTNF-alpha) and recombinant human interferon-gamma (rIFN-gamma) was investigated. rTNF-alpha had cytostatic or cytolytic effects on only some tumor cell lines. When administered together with rIFN-gamma, rTNF-alpha showed enhanced antiproliferative effects on a subset of the cell lines tested. In contrast to its effects on sensitive tumor cells, rTNF-alpha augmented the growth of normal diploid fibroblasts. Variations in the proliferative response induced by rTNF-alpha were apparently not due to differences in either the number of binding sites per cell or their affinity for rTNF-alpha. These observations indicate that the effects of rTNF-alpha on cell growth are not limited to tumor cells, but rather that this protein may have a broad spectrum of activities in vivo.

Chemical carcinogen-induced transplantable fibrosarcomas in histocompatible chickens. I. Incidence of tumor induction in normal and bursectomized chickens.

Transplantable fibrosarcomas were developed in two B-locus-defined chicken strains from primary tumors induced by im injection of 2 mg 7,12-dimethylbenz[a]anthracene in 0.1 ml dimethyl sulfoxide into 1- to 2-week-old chicks. Viruses were not important factors in transmission of these tumors as evidenced by 1) transplantability only within the chicken strain of origin, 2) lack of evidence for a filterable agent, 3) maintenance of donor karyotypic characteristics upon transplantation, 4) lack of DNA polymerase and avian leukosis virus group-specific protein production in vitro. Bursectomized inbred SC chickens had a higher incidence of tumor induction than did normals of the same strain. Although the exact interpretation of this finding posed some problems, as discussed, an important function of enhancing antibody in tumor growth appeared excluded.

Chemical carcinogen-induced transplantable fibrosarcomas in histocompatible chickens. II. Effect of age and thymectomy on tumor incidence.

The incidence of primary fibrosarcoma 2-4 months after im injection of 7,12-dimethylbenz[a]anthracene (DMBA) was studied in normal, neonatally thymectomized and bursectomized SC (B2/B2) chickens. The tumor incidence was not significantly increased in thymectomized chickens inoculated at 1 week of age, but thymectomized animals inoculated at 4 weeks of age developed a higher incidence of tumors than did controls. Bursectomy did not affect tumor induction. Whereas thymectomy and bursectomy clearly reduced T- and B-cell immune responses, respectively, neither the carcinogen nor the presence of tumor had a detectable effect on the immune response. The effect of varying the age of chickens at the time of carcinogen injection was also studied. DMBA injected into chickens at 8-12 weeks of age produced a significantly lower incidence of tumors than did a similar dose of DMBA injected into chickens at 1-4 weeks of age. Thus DMBA-induced tumors in the chicken may present an interesting model for studies on immune surveillance.

Multiple lymphokine production by a phorbol ester-stimulated mouse thymoma: relationship to cell cycle events.

Interleukin 2 (IL-2) production was studied in a subclone of the murine thymoma EL 4. Phenotypic characterization revealed the EL 4-17-2 line to be Thy-1.2+, Lyt-1.2+, and Lyt-2.2-. Costimulation with 500 ng 12-O-tetradecanoylphorbol 13-acetate (TPA)/ml and 5 micrograms concanavalin A (Con A)/ml induced optimal levels of IL-2. Three related phorbol esters stimulated comparable levels of IL-2 when used in conjunction with Con A. Kinetic experiments indicated that IL-2 first became detectable at 2 hours in TPA-treated cultures, whereas in cultures stimulated with Con A alone IL-2 production was not evident until 8 hours. Flow cytometry indicated that TPA and its related phorbol esters cause a perturbation in the cycling of the cell which may be related to increased IL-2 production. Under the conditions examined, no interferon-gamma (IFN-gamma) was detectable. Conversely, both granulocyte-macrophage colony-stimulating factor (CSF-GM) and interleukin-3 (IL-3) were found under conditions that led to stimulation of IL-2 synthesis. CSF-GM was produced in cultures treated singly with 500 ng TPA/ml or with Con A. IL-3 production was similar to IL-2 production, because optimal levels were found in cultures after combined treatment with phorbol ester and mitogen.

Characterization of interleukin 2-dependent cytotoxic T-cell clones: specificity, cell surface phenotype, and susceptibility to blocking by Lyt antisera.

Cytotoxic T-cells were derived from the peritoneal cavity of a C57BL/6 mouse immunized with BALB/c sarcoma Meth A and from the spleens of BALB/c x C57BL/6 F1 (hereafter called CB6F1) mice immunized with BALB/c leukemia RL male 1. The cells were cultured in interleukin 2 and cloned by limiting dilution, and their specificity was determined by direct tests and competitive inhibition assays. C57BL/6 anti-Meth A effector cells recognized H-2Dd determinants. CB6F1 anti-RL male 1 effector cells recognized a unique cell surface antigen of leukemia RL male 1. The specificity was maintained in long-term culture. The cell surface phenotype of the cloned effector cell lines as determined by absorption analysis was Thy-1.2+, Lyt-1.2+, 2.2+, and 3.2+. Cytotoxicity was blocked at the target cell level by antisera against H-2Dd, but not H-2Dk or H-2b, and at the effector cell level by antisera against Lyt-2.2 and 3.2, but not Lyt-1.2, Ly-5.1 or Thy-1.2.

Expression of a shared tumor-specific antigen by two chemically induced BALB/c sarcomas.

A tumor-specific antigen (TSA) expressed on the chemically induced BALB/c Meth A sarcoma and one of 22 other BALB/c sarcomas tested, CMS13, was detected in in vitro cellular and humoral assays. The distribution pattern of the TSA defined in a complement-dependent microcytoxicity assay by cytotoxic antibodies present in CMS13 antisera was similar to that detected by a cytotoxic T-cell clone, designated CTLL-MA10B, in an 18-h cell-mediated cytotoxicity assay. The serologically defined TSA was shown to be expressed on gp96, a Mr 96,000 glycoprotein isolated from Meth A cytosol with immunoprotective activity in in vivo tumor rejection assays. Immunization of BALB/c mice with Meth A, CMS13, or preparations of gp96 isolated from these sarcomas induced tumor resistance in these mice to Meth A and CMS13 but not CMS5, an antigenically unrelated sarcoma. These results suggest that the shared TSA is expressed on gp96 and is functional in tumor rejection assays.

Circulating cytokines in patients with metastatic cancer treated with recombinant interleukin 2 and lymphokine-activated killer cells.

Treatment with recombinant interleukin 2 and lymphokine-activated killer cells (rIL-2/LAK) has produced a clinical antitumor effect in preliminary human trials. The cytokines gamma-interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), and tumor necrosis factor beta (TNF-beta, lymphotoxin) have potent in vitro antitumor activity and some clinical toxicities similar to interleukin 2 (IL-2)/LAK. This study sought to determine whether these cytokines were detectable in sera of IL-2/LAK-treated patients. Ten patients were treated with a protocol of 5-day i.v. rIL-2 bolus priming (10(5) units/kg, every 8 h), followed by 5 daily phereses with harvested lymphocytes cultured in vitro to generate LAK, and 5 days of rIL-2 bolus with infusion of LAK cells. Five patients were treated with a protocol modified to a 3-day rIL-2 prime and 6-day continuous infusion rIL-2 (3 x 10(6) units/m2/day) with infusion of LAK cells. Serum specimens were obtained prior to and 0.5, 2, 3, and 5 h after IL-2 or LAK cell administrations. IFN-gamma was detected by enzyme-linked immunosorbent assay, TNF-alpha by WEHI 164 bioassay or enzyme-linked immunosorbent assay, and TNF-beta by WEHI 164 cell bioassay. During the prime, few patients manifested in vivo detectable serum cytokines: IFN-gamma, three of ten, 5-day prime (1.03 +/- 0.46 ng/ml), and zero of five, 3-day prime; TNF-alpha, one of ten, 5-day prime, and one of three, 3-day prime; TNF-beta, one of ten, 5-day prime. The supernatants of in vitro LAK generation cultures had detectable levels of cytokines at 24 h which increased progressively until culture harvest at Day 4 (IFN-gamma, 2.56 +/- 0.34 ng/ml; TNF-alpha, 356 +/- 110 pg/ml; TNF-beta, 8.2 +/- 4.4 units/ml). The highest levels of in vivo serum cytokines occurred following LAK cell infusion and were more often elevated in patients receiving rIL-2 by bolus than by continuous infusion: IFN-gamma, four of six bolus, zero of three continuous infusion; TNF-alpha, six of six bolus (maximum 679 pg/ml) versus two of three continuous infusion (maximum, 106 pg/ml). LAK cells in vitro responded with cytokine release on stimulation by tumor cell lines (IFN-gamma, 0.88 +/- 0.06 ng/ml; TNF-alpha, 426 +/- 16 pg/ml; TNF-beta, 0.64 +/- 0.06 units/ml). In summary, this preliminary study has detected circulating cytokines in sera of patients receiving IL-2/LAK therapy. The greatest cytokine elevations followed LAK cell infusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Increased transforming growth factor beta expression inhibits cell proliferation in vitro, yet increases tumorigenicity and tumor growth of Meth A sarcoma cells.

Several observations correlate increased expression of transforming growth factor (TGF) beta 1 with tumorigenesis, suggesting that expression of this multifunctional growth factor may provide an advantage in tumor formation. However, many tumor cells are inhibited in their proliferation by TGF-beta in vitro, thus suggesting that TGF-beta synthesis could exert an antiproliferative effect on tumor formation. To evaluate the physiological relevance of increased TGF-beta 1 synthesis in such tumor cells which are strongly inhibited in their proliferation by TGF-beta, we chose Meth A sarcoma cells as a model system. We established cell clones overexpressing TGF-beta 1 and determined its effect on tumor formation in mice that are not immunocompromised. Increased expression of biologically active TGF-beta 1 resulted in a profound growth inhibition in the transfected clones and increased adhesiveness in vitro. However, these cells were much more tumorigenic than Meth A cells that did not overexpress TGF-beta 1, as assessed by both tumor incidence and tumor growth. In addition, parental Meth A cells were inhibited in their tumor formation by neutralizing TGF-beta antibodies and stimulated by exogenous TGF-beta. Our results thus provide evidence that increased TGF-beta synthesis provides a major advantage for tumorigenesis, even if the cells are growth inhibited by their endogenous TGF-beta synthesis in culture. These results suggest that, in vivo, direct effects of TGF-beta on the tumor environment, such as increased extracellular matrix formation and cell-matrix interactions, and local suppression of the immune surveillance may provide a growth advantage which overrules any direct antiproliferative effects of TGF-beta, as suggested by the effects in culture.

Comparison of combinations of interferons with tumor specific and nonspecific monoclonal antibodies as therapy for murine B- and T-cell lymphomas.

Two murine models, C3H 38C13 B-cell lymphoma and AKR SL2 T-cell lymphoma were used to determine the efficacy of three different interferon preparations, recombinant human hybrid interferon-alpha A/D, recombinant murine interferon (rMIFN)-gamma, and natural MIFN-alpha/beta (greater than or equal to 85% beta), alone and in combination with tumor specific and nonspecific monoclonal antibody therapy. All three interferon preparations have direct in vitro antigrowth activity for 38C13 and SL2. All three interferons have direct antitumor activity in vivo for 38C13 lymphoma at high doses; however, none of these interferons has independent antitumor activity for SL2 in vivo. These data indicate that there is no relationship between in vitro growth cytostasis/cytolysis and in vivo antitumor response. All three interferon preparations will potentiate both tumor specific and nonspecific monoclonal antibody therapy. Natural MIFN-alpha/beta and recombinant human hybrid interferon-alpha A/D, which should share a common cell surface receptor, had similar antitumor activity in both models. Combining recombinant human hybrid interferon-alpha A/D and rMIFN-gamma therapy was not additive for 38C13 lymphoma and a three-way combination with antiidiotype was not significantly more effective than combination therapy with one interferon type. In general, rMIFN-gamma was more effective in in vivo combination therapy against the s.c. T-cell lymphoma than against the i.p. B-cell lymphoma and was more synergistic with anti-Thy1.1 than with antiidiotype.