Antitumor and antimetastatic activities of human recombinant interferon alpha A/D

Interferon signaling in cancer. Non-canonical pathways and control of intracellular immune checkpoints

The interferons (IFNs) are cytokines with important antineoplastic and immune modulatory effects. These cytokines have been conserved through evolution as important elements of the immune surveillance against cancer. Despite this, defining their precise and specific roles in the generation of antitumor responses remains challenging. Emerging evidence suggests the existence of previously unknown roles for IFNs in the control of the immune response against cancer that may redefine our understanding on how these cytokines function. Beyond the engagement of classical JAK-STAT signaling pathways that promote transcription and expression of gene products, the IFNs engage multiple other signaling cascades to generate products that mediate biological responses and outcomes. There is recent emerging evidence indicating that IFNs control the expression of both traditional immune checkpoints like the PD-L1/PD1 axis, but also less well understood "intracellular" immune checkpoints whose targeting may define new approaches for the treatment of malignancies.

Inhibition of Angiogenesis by Type I Interferons in Models of Kaposi'S Sarcoma

Kaposi's Sarcoma (KS) is a pathology which occurs with increased frequency and in a particularly aggressive form in AIDS patients. The HIV-1 Tat protein appears to be an important co-factor in the induction of the extensive neo-vascularization associated with AIDS-KS. Tat acts as a chemoattractant for endothelial cells in vitro, inducing both chemotactic and invasive responses. Several clinical trials have been performed testing the effectiveness of diverse biological agents in therapy of KS, among these the type I interferons. Type I IFNs have diverse biological functions besides their anti-viral activity, including anti-angiogenic properties. We have shown that IFNα and IFNβ are potent inhibitors of both primary and immortalized endothelial cell migration and morphogenesis in vitro as well as neo-angiogenesis induced by HIV-1 Tat in vivo. The inhibitory effect of IFN class I on HIV-Tat associated angiogenesis further supports its use as a therapy for epidemic Kaposi's sarcoma. The use of recombinant IFNs at the levels required to obtain a therapeutic effect are associated with side effects and toxicity, therefore we are now developing a gene therapy approach for constant and local delivery type I IFNs.

Anti-metastatic functions of type 1 interferons: Foundation for the adjuvant therapy of cancer

The anti-tumorigenic effects that type 1 interferons (IFN1) elicited in the in vitro studies prompted consideration of IFN1 as a potent candidate for clinical treatment. Though not all patients responded to IFN1, clinical trials have shown that patients with high risk melanoma, a highly refractory solid malignancy, benefit greatly from intermediate IFN1 treatment in regards to relapse-free and distant-metastasis-free survival. The mechanisms by which IFN1 treatment at early stages of disease suppress tumor recurrence or metastatic incidence are not fully understood. Intracellular IFN1 signaling is known to affect cell differentiation, proliferation, and apoptosis. Moreover, recent studies have revealed specific IFN1-regulated genes that may contribute to IFN1-mediated suppression of cancer progression and metastasis. In concert, expression of these different IFN1 stimulated genes may impede numerous mechanisms that mediate metastatic process. Though, IFN1 treatment is still utilized as part of standard care for metastatic melanoma (alone or in combination with other therapies), cancers find the ways to develop insensitivity to IFN1 treatment allowing for unconstrained disease progression. To determine how and when IFN1 treatment would be most efficacious during disease progression, we must understand how IFN1 signaling affects different metastasis steps. Here, we specifically focus on the anti-metastatic role of endogenous IFN1 and parameters that may help to use pharmaceutical IFN1 in the adjuvant treatment to prevent cancer recurrence and metastatic disease.

beta Interferon inhibits HIV-1 Tat-induced angiogenesis: synergism with 13-cis retinoic acid

Kaposi's sarcoma (KS) is a highly angiogenic lesion which frequently presents as an aggressive form in HIV-infected male patients. We have previously shown that the HIV-1 Tat protein induces endothelial cell migration and invasion in vitro and a rapid angiogenic response in vivo, suggesting that it acts as a cofactor in epidemic KS. In this study we tested beta interferon (IFN beta) and retinoic acid (RA) for the inhibition of Tat-induced angiogenesis using in vivo and in vitro models. IFN beta, at a concentration above 2500 U/ml, was an effective inhibitor of Tat-stimulated growth, migration and morphogenesis of an endothelial cell line in vitro and of angiogenesis in vivo. A strong reduction of properties associated with neovascularisation was induced by 10,000 U/ml. In vivo, RA alone was on ineffective inhibitor of angiogenesis, and in vitro gave only a limited inhibition of endothelial cell growth. However, 13-cis RA used in combination with IFN beta impressively potentiated its effects. A combination of lower doses of IFN beta (2500 U/ml) and 13-cis RA induced a virtually complete inhibition of the Tat-related angiogenic phenotype both in vivo and in vitro. The potentiation of the anti-angiogenic activity of IFN beta by 13-cis RA suggests that this combination could be a useful approach for the therapy of epidemic KS.

Enhanced in vivo sensitivity to interferon with in vitro resistant B16 tumor cells in mice

Mouse B16 melanoma cells rapidly develop resistance to the antiproliferative effects of interferon alpha (IFN alpha) and interferon beta (IFN beta) when they are exposed to the interferons in vitro. This resistance was characterized to be non-genetic and dose-dependent, and does not alter other IFN-induced effects such as antiviral effects and elevation of 2',5'-oligoadenylate synthetase activity in IFN-treated cells. The study of these IFN-resistant cells has been extended to an in vivo tumor model. Resistance, if it occurred in vivo, did not adversely affect the survival of IFN-treated mice. Further, IFN-treated mice inoculated with B16 cells that were resistant in vitro (B16 alpha res cells) survived significantly longer than IFN-treated mice inoculated with B16 cells that were sensitive in vitro. The IFN-treated B16 alpha res-inoculated mice had a significantly higher cure rate as well. The prolonged survival of the mice bearing B16 alpha res cell tumors did not seem to be caused by the slower growth rate of the B16 alpha res cells, since experiments performed with a tenfold higher B16 alpha res cell inoculum and a tenfold lower B16 cell inoculum did not show any change in the survival pattern. It is clear that in vitro resistant B16 alpha res cells are more sensitive to antitumor effects induced by IFN in vivo than in vitro sensitive B16 cells.

Recombinant interferon alpha and gamma modulate the invasive potential of human melanoma in vitro

We have studied the effects of interferons (IFNs) on the attachment, collagenase IV activity, chemotactic migration and in vitro invasion of human melanoma (A2058) cells treated for various time periods with human recombinant interferon alpha (hrIFN-alpha) or gamma (hrIFN-gamma). The cells treated with hrIFN alpha for a short time period attached more readily to purified basement membrane components, type IV collagen and laminin, than control cells. The stimulating effect of hrIFN gamma on the attachment was seen, however, when the cells were treated for a longer period of time (3 days) with this drug. The short-term treatment with hrIFN alpha also enhanced the in vitro invasion of cells through a reconstituted basement membrane compared to findings with untreated control cells. Pre-treatment of 3 days or more was, however, needed for hrIFN gamma to promote the invasion of A2058 cells. Both IFNs increased the secretion of basement membrane (type IV) collagen degrading metalloproteinase (collagenase IV) activity from human melanoma cells. Further, chemotaxis, i.e., directed migration of A2058 cells to laminin, was enhanced by both IFNs. In contrast, the attachment, collagenase IV activity, chemotaxis, and in vitro invasion were markedly inhibited when the cells were treated for an extended time period (7 days) with the IFNs. Interferons also inhibited cell proliferation after 4 days of exposure. These results suggest that time of treatment with interferons modulates the invasive capacity of human melanoma cells in vitro, causing initially a transient enhancement of invasion followed by an inhibition of invasive propensity after extended exposure to these drugs, and that different biochemical steps required for successful invasion are regulated in parallel by interferons alpha and gamma.

Antitumor activity of T cells in lymphoid organs induced by interferon in tumor-bearing mice

Administration of human hybrid interferon-alpha A/D (IFN) for 5 consecutive days induced antitumor activity in spleen of Meth A fibrosarcoma-bearing mice 9-10 days after cessation of IFN administration. Antitumor activity assayed by the in vivo neutralization test was found in the spleen of responding mice but not in that of progressive mice. This activity was T-cell-dependent and tumor-selective. However, tumor-neutralizing activity was not found in spleen recovered as early as 3 days after cessation of IFN administration when many tumor cells are still surviving in tumor nodules and being attacked by the host. Instead, T-cell-dependent and tumor-selective tumor-neutralizing activity was found in the lymph node of tumor-bearing mice at this early stage. Furthermore, the tumor-neutralizing activity was already detected in the lymph nodes during the course of IFN administration, although there was no difference in the cell composition of the lymph nodes of IFN- and placebo-administered mice. Since IFN-alpha is apparently not a direct modifier of T cells, these results indicate that IFN probably did not directly increase the number of antitumor T cells but instead modified the host-tumor interaction in such a way that, as an early event, the enhanced T-cell response to tumor cells occurred, resulting in an increase in the antitumor T-cell population in lymph nodes. We supposed that, as the tumor regressed, these antitumor T cells would eventually leave the lymph node and migrate to the spleen.

Inhibition of lung colonization of mouse colon 26 adenocarcinoma by recombinant mouse interferon beta through a modification of platelet function

Recombinant murine interferon beta (MuIFN-beta) given i.v. efficiently inhibited both pulmonary arrest and formation of lung colonies of NL-17, a highly metastatic variant of mouse colon adenocarcinoma 26. NL-17 was rather resistant to MuIFN-beta in vitro and was highly resistant to natural killer cells of mice even though they were treated in vivo with MuIFN-beta. Platelets isolated from MuIFN-beta-treated mice showed reduced aggregating activity induced by NL-17. Since lung colonization by NL-17 is influenced by platelet aggregation, the inhibition of colonization by MuIFN-beta could be partly mediated through modification of platelet function in vivo. The effect of MuIFN-beta on platelet function and its subsequent inhibition of lung colony formation give new insights into the action of recombinant MuIFN-beta.

Combination therapy of colon carcinoma 26 in mice with recombinant human interleukin-2 and interferon-alpha A/D: occurrence of large granular cells in the tumor

The antitumor effects of recombinant human interleukin-2 (rIL-2), in combination with recombinant human interferon-alpha A/D hybrid (rIFN-alpha A/D) on colon carcinoma 26 (colon 26) in mice were examined histologically. Colon 26 was transplanted subcutaneously into female BALB/c mice on day 0. The mice bearing the tumor received intramuscular injections of rIL-2, rIFN-alpha A/D or the combination of rIL-2 and rIFN-alpha A/D for 2-10 consecutive days starting on day 7. Mice were killed on days 9, 13, 17 and 21. After day 13, growth of the tumor was significantly suppressed in the mice treated with rIL-2 or rIFN-alpha A/D alone and was stopped in the mice treated with rIL-2 in combination with rIFN-alpha A/D. Histologically, tumor necrosis developed in all treated groups, though the degree was the most severe in the group receiving combination treatment. Many large cells (about 15-30 microns in diameter) infiltrated into the tumor, and they had Thy-1 surface antigen and many periodic acid-Schiff-positive round granules in the cytoplasm. The incidence of these large granular cells was correlated well with the reduction in tumor weight. The ultrastructural features of the large granular cells were very similar to those of murine large granular lymphocyte-like cells maintained in vitro in an IL-2-containing medium. The present large granular cells appear to be a kind of activated lymphoid cells.

In vivo effects of recombinant interferon alpha A/D incorporated in gelatin microspheres on murine tumor cell growth

Intraperitoneal (ip) injections of gelatin microspheres containing a very small amount of recombinant human interferon alpha A/D (A/D-IFN) (IFN-microspheres) plus free A/D-IFN improved the survival of mice bearing ascitic Meth A-R1 cells which we had isolated as IFN-resistant cells under in vitro conditions. The dose of free A/D-IFN in one injection was 10,000 IU, which was insufficient by itself for manifesting in vivo antitumor activity. In these mice, in vivo R1 cell growth was suppressed and macrophage recruitment was enhanced in comparison with mice receiving other control agents. Administration of IFN-microspheres alone was also effective but less than that of IFN-microspheres plus free A/D-IFN. Peritoneal macrophages obtained from normal or R1-bearing mice receiving ip injection of IFN-microspheres with or without free A/D-IFN were activated to inhibit the in vitro growth of R1 cells. The intratumoral injection of IFN-microspheres strongly inhibited the growth of solid R1 tumors. Intravenous injection of IFN-microspheres was effective in preventing the pulmonary metastasis of B16 melanoma cells. These results indicate that the IFN-microsphere is much more effective against tumors than free A/D-IFN.

Action of recombinant alpha interferon against experimental and spontaneous metastases in a murine model

The therapeutic potential of rHuIFN-alpha A/D, a hybrid human IFN molecule with equal activity on murine cells, was studied in experimental and spontaneous metastatic models of a murine colon carcinoma COLON 26. rHuIFN-alpha A/D inhibited experimental pulmonary metastases of COLON 26 and prolonged the survival of BALB/c mice. Dose scheduling, survival and tumour-cell clearance studies showed that the first 5 days were critical in the inhibition of pulmonary metastases. However, it is unlikely that lung NK cells were involved in the anti-metastatic effect of rHuIFN-alpha A/D because inhibition of pulmonary metastases and a decrease in radio-labelled tumour-cell survival was seen in BALB/c mice depleted selectively of their NK cells by prior treatment with rabbit antiasialoGMI serum. Although rHuIFN-alpha A/D stimulated NK-cell activity in BALB/c mice, it was ineffective in abrogating the NK suppressant action of rabbit anti-asialoGMI serum on murine lung NK cells. Thus, IFN may mediate its early antimetastatic effect via a mechanism independent of NK-cell stimulation. IFN also inhibited the development of lung metastases from s.c. COLON 26 tumors in normal, NK-depleted and T-cell-deficient mice.

Purification and properties of a novel recombinant human hybrid interferon, delta-4 alpha 2/alpha 1

The human interferon (huIFN) delta-4 alpha 2(5-62)/alpha 1(64-166) is a genetically engineered hybrid that consists of residues 5-62 of huIFN alpha 2 and residues 64-166 of huIFN alpha 1. This variant contains four cysteine residues at positions 29, 86, 99 and 139, but does not contain the cysteine at position 1 that is characteristic of naturally occurring huIFN alpha subtypes. This novel recombinant hybrid was purified from Escherichia coli to greater than 95% homogeneity. The purification was based on ethanol extraction of a trichloroacetic acid precipitate and Matrex Gel Blue A chromatography followed by either a selective precipitation or DEAE-Sepharose chromatography. The purified protein that was treated with 2-mercaptoethanol exhibited two closely migrating bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with apparent molecular weight values of 17,800 and 17,100, both of which exhibited antiviral activity. Electrophoresis performed without prior reduction with 2-mercaptoethanol indicated only a minor extent of intermolecular disulfide bonding. The purified protein exhibited a high specific antiviral activity of 7 x 10(7) units/mg when assayed on human fibroblast cells and, in distinction to the parental huIFN alpha 2, it also demonstrated antiviral activity on human fibroblast cells and, in distinction to the parental huIFN alpha 2, it also demonstrated antiviral activity on murine L929 cells. The level of antiproliferative activity of huIFN delta-4 alpha 2(5-62)/alpha 1(64-166) on various cell lines of different histological origin appeared to be more comparable to that of huIFN alpha 1 than huIFN alpha 2. The data suggest that huIFN delta-4 alpha 2(5-62)/alpha 1(64-166) hybrid may be a useful tool for understanding huIFN structure-function relations.

Human interferons inhibit experimental metastases of a human melanoma cell line in nude mice

Therapy with human lymphoblastoid interferon HuIFN-alpha(N1), or recombinant human interferon gamma, rHuIFN-gamma, inhibited experimental pulmonary metastases of the human melanoma cell line, DX3-azac, in BALB/c nude mice and significantly prolonged survival. The human IFNs had no effect on nude mouse lung and spleen NK cell activity, lung macrophage activity, haemoglobin or white cell counts. HuIFN-alpha(N1) had no effect on the levels of the IFN induced enzyme 2-5A synthetase in nude mouse lungs although the rHuIFN-gamma caused some elevation. In addition, clearance of radiolabelled DX3-azac cells was identical in control or human IFN treated mice, and there was no histological evidence of an increase in immune effector cells associated with the metastatic lesions in treated mice. Human IFN therapy did not affect the state of differentiation of the melanoma cells in vivo as measured by melanin content, but both IFNs inhibited the development of colonies of DX3-azac cells in vitro. We conclude that in this model system IFNs have direct anti-proliferative effects on metastatic cells.

Potentiation of antitumor activity of macrophages by recombinant interferon alpha A/D contained in gelatin microspheres

Gelatin microspheres containing recombinant human interferon alpha A/D (A/D-IFN) (IFN-microspheres) potentiated the antitumor activity of mouse peritoneal macrophages (M phi) much more efficiently than free A/D-IFN. M phi acquired the inhibitory activity on tumor cell growth by the ingestion of IFN-microspheres without the aid of lipopolysaccharide (LPS), though LPS was required as a second signal for activating M phi primed with free IFN. The IFN-microspheres were much more efficient than free IFN plus LPS in respect of the IFN amount and the time required for M phi activation. Furthermore, M phi pretreated with the IFN-microspheres maintained their activated state for a much longer period than those pretreated with free A/D-IFN plus LPS. A monoclonal anti-IFN-alpha A antibody, which was capable of neutralizing A/D-IFN, did not interfere with the M phi activation by the IFN-microspheres. Even human IFN-alpha A was effective in activating murine M phi similarly to A/D-IFN, when given in the form of IFN-microspheres, though human IFN-alpha A in the free form was ineffective. These results argue that the mechanism of M phi activation by the IFN-microspheres is different from that by free IFN.

Interferon treatment markedly inhibits the development of tumor metastases in the liver and spleen and increases survival time of mice after intravenous inoculation of Friend erythroleukemia cells

To investigate the effect of interferon treatment on the development of tumor metastases, DBA/2 mice were injected i.v. with 2 X 10(6) Friend erythroleukemia cells (FLC) (equivalent to about 5 X 10(5) LD50). FLC multiplied rapidly in the liver and spleen and all untreated or control treated mice died between 7 and 12 days. Daily treatment of mice with potent preparations of mouse interferon alpha/beta was initiated 3 to 72 hr after i.v. inoculation of tumor cells, at times when FLC were already present in the liver and spleen. Interferon treatment resulted in a 100 to 1,000-fold inhibition of the multiplication of FLC in the liver and spleen and a marked increase in mean survival time. Small numbers of tumor cells persisted in the liver and spleen in some interferon-treated mice and could be recovered by bioassay several weeks after tumor inoculation. Most interferon-treated mice died with tumor in the ensuing months. Three of 34 interferon-treated mice were considered cured as they were alive at 386, 325 and 284 days after tumor inoculation. Daily treatment of tumor-inoculated mice with human recombinant interferons alpha D and alpha BDDD, which had antiviral activity on mouse cells in culture, also increased the survival time of mice injected i.v. with FLC. The use of the interferon-resistant 3C18 line of FLC suggests that the marked inhibition of development of established liver and spleen metastases was not due to a direct effect of interferon on the tumor cells, but was host-mediated.

In vitro effects of beta-interferon on steroid receptors and prostaglandin output in human endometrial adenocarcinoma

The effect of natural beta-interferon (beta-IFN) on steroid receptor levels and output of prostaglandins (PGs) was investigated in human endometrial cancer. beta-IFN determines in endometrial adenocarcinoma explants an increase of cytosolic estradiol (ER) and progesterone (PR) receptors at concentrations ranging from 10 to 1000 IU/ml of culture medium. Only cases in which there was an enhancement of at least 50% with respect to control values were considered. Low concentrations of beta-IFN (10 IU/ml of culture medium) produce an enhancement of ER in 60% and of PR in 42% of cases, while higher concentrations of beta-IFN (1000 IU/ml of culture medium) produce an enhancement of ER in 32%, and of PR in 82% of cases. Since PGs are involved in proliferation control in a large variety of tumors, we evaluated the ratio between PGF2-alpha and PGE2 levels in culture medium. This ratio increased, in our experimental model, after treatment with 10 and 1000 IU/ml of beta-IFN in 38% and 58% of cases respectively. Our data suggest that beta-IFN could affect cellular hormone sensitivity through a modification of ER and PR and it can also determine a variation of PG output in human endometrial cancer.

Anti-tumor effects of interferon in mice injected with interferon-sensitive and interferon-resistant Friend leukemia cells. VI. Adjuvant therapy after surgery in the inhibition of liver and spleen metastases

Adult DBA/2 mice were injected s.c. with the highly malignant, interferon-resistant 3C18 line of Friend erythroleukemia cells (FLC). Eight or 9 days after established s.c. tumors had developed, the primary tumor was excised and mice were treated i.p. with either mouse interferon alpha/beta or a control preparation. At the time of surgery, mice already had tumor cells in the liver. All control-treated mice died in the ensuing 2 weeks with extensive tumor metastases in the liver and spleen. Interferon treatment resulted in an inhibition of the development of liver and spleen metastases and a markedly increased survival time. We conclude that interferon alpha/beta is effective as adjuvant therapy after surgery for metastatic disease in mice.

Regulatory effects on macrophages of human recombinant interferons-alpha

The regulatory effects of human recombinant and hybrid interferons-alpha (IFN-alpha) on macrophage-mediated tumoricidal activity were examined. Recombinant hybrid IFN-alpha-A/D suppressed the capacity of murine interferon-gamma (IFN-gamma) to activate mouse peritoneal macrophages to a tumorilytic state, and blocked the killing of syngeneic syngeneic melanoma target cells by macrophages previously committed to the cytotoxic phenotype with a 4-h pretreatment with IFN-gamma. This suppressive activity was limited to IFN-alpha-A/D, as IFN-alpha-A and IFN-alpha-D were not effective. In contrast, IFN-alpha-A, -D, and -A/D were all capable of activating human peripheral blood monocytes to lyse human tumor cells. When encapsulated in liposomes, only IFN-alpha-A/D maintained its monocyte activating efficacy. These findings suggest that the immunomodulatory effects of IFN-alpha subtypes and hybrid molecules are dependent on species of monocytes/macrophages, subtype, and nature of presentation to effector cells.

Restoration by recombinant interferon alpha A/D of host defense systems against tumor in immunosuppressed mice

Recombinant human interferon alpha A/D (alpha A/D) restored or augmented host defense systems against tumors in immunosuppressed mice. In normal C57BL/6 mice, inoculation of B16 melanoma F1 cells caused few pulmonary metastasis, whereas in mice pretreated with cyclophosphamide (CY) it caused a high incidence of pulmonary metastasis, leading to earlier death than in the normal mice inoculated with the same dose of the tumor. alpha A/D given after the CY treatment counteracted the deleterious effects of the CY treatment. Since such restorative activity was seen even against the subline of B16 F1 which had been made resistant to its direct antiproliferative effect, alpha A/D seems to exert its effect indirectly through host defense systems. However, this activity of alpha A/D in the mice pretreated with CY was abrogated by inoculation of anti-asialo GM1 serum but not by i-carrageenan. The CY treatment reduced NK activity, while alpha A/D given after the CY treatment restored or augmented the NK cell activity in lung cells and peripheral blood mononuclear cells, but not in spleen cells. These findings suggest that the restoration or augmentation of NK activity in the lung and/or peripheral blood might be the major factor leading to the antimetastatic activity of alpha A/D in the mice treated with CY.