Efficacy of combined interferon cyclophosphamide therapy after diagnosis of lymphoma in AKR mice

Alpha-2 Interferon and 5-Fluorouracil in Advanced Colorectal Cancer

A total of 21 untreated patients (5 males, 16 females; median age, 55 years; range, 28-72) with advanced measurable colorectal carcinoma were treated with an association of 5-fluorouracil (1000 mg/weekly) and alpha-2 interferon (three times a week s.c.: 6 x 10(6) U in the 1st month, 9 x 10(6) U in the 2nd month, 12 x 10(6) U in the 3rd month and then 18 x 10(6) U) until maximum response or progression of disease. Sites of disease involved liver in 10 patients, lung in 6, supraclavicular lymph nodes in 3, skin in 1, abdomen in 4, and vagina in 1 patient. Nine responses (42.8%) were documented (4 complete and 5 partial) with metastases confined to the liver, lung, nodes and skin. Median duration of response was 11 months (range, 4-17+) and median survival was 10 months (range, 2-17+). Side effects (fever, flu-like syndrome and leukopenia) required a dose reduction of 5-fluorouracil in 8 patients and interferon in 2 patients.

Sequential Treatment with Interferon and Chemotherapy of Metastatic Malignant Melanoma. Total Remission of Cutaneous and Visceral Metastasis, but not of Cerebral Metastasis

A woman 35 years of age suffering from cutaneous and visceral metastatic melanoma was treated with recombinant Interferon α 2b (rIFNα2b) subcutaneously 3 × 106 U/m2 3 times a week for 3 months with no apparent effect on the course of the illness. Two months after IFN therapy the patient developed cerebral metastasis. A cycle of carmustine, 100 mg/day for 3 days, was given, and complete disappearance of the cutaneous and visceral, but not of the cerebral manifestations was observed. Two consolidation cycles based on vincristine, dacarbazine and lomustine were then administered. The patient died 26 months after beginning treatment with IFN and 18 months after chemotherapy for the cerebral metastasis. No trace of tumor at the cutaneous or visceral level was found at autopsy.

Meta-Analysis to Evaluate the Role of Interferon in Follicular Lymphoma

Purpose

To determine whether interferon (IFN) -α2, when given with or following chemotherapy, influences response rate, remission duration, and survival in newly diagnosed patients with follicular lymphoma.

Patients and Methods

Ten phase III studies evaluating the role of IFN-α2 in 1,922 newly diagnosed patients with follicular lymphoma were analyzed. Updated individual patient data were used to perform meta-analyses for response, survival, and remission duration.

Results

The addition of IFN-α2 to initial chemotherapy did not significantly influence response rate. An overall meta-analysis for survival showed a significant difference in favor of IFN-α2, but also showed significant heterogeneity between studies. Further analyses were carried out in order to explain this heterogeneity, and to define the circumstances in which IFN-α2 prolonged survival. The survival advantage was seen when IFN-α2 was given: (1) in conjunction with relatively intensive initial chemotherapy (2P = .00005), (2) at a dose ≥ 5 million units (2P = .000002), (3) at a cumulative dose ≥ 36 million units per month (2P = .000008), and (4) with chemotherapy rather than as maintenance therapy (P = .004). With regard to remission duration, there was also a significant difference in favor of IFN-α2, irrespective of the intensity of chemotherapy used, IFN dose, or whether IFN was given as a maintenance strategy or with chemotherapy.

Conclusion

When given in the context of relatively intensive initial chemotherapy, and at a dose ≥ 5 million units (≥ 36 × 106 units per month), IFN-α2 prolongs survival and remission duration in patients with follicular lymphoma.

A randomized controlled trial to evaluate the role of interferon as initial and maintenance therapy in patients with follicular lymphoma

The purpose of this study was to evaluate the role of interferon as initial and maintenance therapy in patients with newly diagnosed follicular lymphoma. Between 1984 and 1994, 204 patients with newly diagnosed Stage III or Stage IV follicular lymphoma were randomized to receive either, Chlorambucil (CB): 10 mg daily for 6 weeks, followed by a 2-week interval, with 3 subsequent 2-week treatment periods at the same dose, separated by 2-week intervals, or, CB given concurrently with interferon (IFN). IFN was given at a dose of 3 x 10(6)units thrice weekly, subcutaneously, throughout the 18-week treatment period. Responding patients were subsequently randomized to receive maintenance IFN at the dose and schedule described above, or to expectant management. The overall response rate was 161/204 (78%), complete remission being achieved in 24% of patients. Neither the addition of IFN to the initial treatment, nor the use of maintenance IFN influenced response rate, remission duration or survival. This study was undertaken to determine whether IFN, given in combination with, and then subsequent to, CB would alter the clinical course of patients with follicular lymphoma. Disappointingly, this objective was not achieved, no advantage having been demonstrated for the addition of IFN.

Positive interactions between human interferon and cepharanthin against human cancer cells in vitro and in vivo

A human tumor microcytotoxicity-viable cell-staining assay was used to test the antiproliferative effect of recombinant human interferon-beta or -gamma alone and in combination with bisbenzylisoquinoline alkaloid cepharanthin against four human tumor cell lines in vitro and in nude mice. Results obtained in the in vitro study indicate that combinations of interferon-beta/-gamma with cepharanthin show synergistic and, occasionally, additive antiproliferative effects in a dose-dependent manner on tumor viable cell-staining assay. Interferon-gamma combined with cepharanthin suppressed the growth of all four human tumor cell lines (RPMI 4788, PC 10, HeLa, ZR-75-1), and this enhanced antiproliferative effect was not dependent on the interferon species involved, including interferon-beta and -gamma. In an experimental model of pulmonary metastasis, in which human colon tumor cells were inoculated i.v. into nude mice, interferon-gamma alone exerted significant inhibitory activity against pulmonary metastasis in a dose-dependent manner, and cepharanthin alone also significantly inhibited metastasis. Furthermore, a combination of interferon-gamma with cepharanthin resulted in a considerable suppression of pulmonary metastasis. These studies indicate that due to their therapeutic potential, combinations of recombinant human interferon-beta or -gamma with cepharanthin might be a promising therapy for pulmonary metastasis of human cancers.

Combination trial of subcutaneous recombinant alpha 2 b interferon and oral cyclophosphamide in follicular low-grade non-Hodgkin's lymphoma

The follicular non-Hodgkin's lymphomas (NHL) have been among those tumors demonstrated to show frequent responses to alpha interferon in phase I and II clinical trials. In addition, there are data suggesting that alpha interferon demonstrates synergistic antitumor activity with alkylating agents in animal models for a number of tumors. Based on these data, Cancer and Leukemia Group B (CALGB) undertook a phase II pilot study of the combination of interferon rIFN alpha 2b (2 x 10(6) IU/m2 s.c. tiw) and cyclophosphamide (100 mg/m2 per day orally) with the ultimate purpose of examining this combination as long-term therapy of follicular lymphoma in comparison to oral cyclophosphamide alone. One hundred five advanced stage III or IV eligible patients with pathologically diagnosed International Working Formulation B or C histology were entered on CALGB 8553 to determine toxicity and response rates to the combination. Both previously chemotherapy-treated patients (32) and patients without prior chemotherapy (73) were entered on study. For patients without prior chemotherapy the overall response rate to the combination regimen was 86% with 58% of chemotherapy-treated patients achieving complete response. Chemotherapy-treated patients had a total response rate of 62% with only 25% complete responders. Complete responses in patients without prior chemotherapy were positively correlated with absence of B symptoms, and good performance status and negatively correlated with the histological subtype of follicular mixed small-cleaved and large cell histology (IWF C); only performance status was significantly correlated with response in patients who had previously had chemotherapy. Survival at 5 years is estimated to be 63% for those without chemotherapy and 39% for those previously treated with chemotherapy patients. The maximum toxicities experienced during therapy with the combination regimen of cyclophosphamide and interferon alpha were primarily related to myelosuppression. Sixty-seven percent of patients without prior chemotherapy and 65% of patients receiving prior chemotherapy experienced severe leukopenia while severe thrombocytopenia and anemia occurred in 6-31% of these patients. Non-myelosuppressive toxicities were less frequently seen. These response rates are similar to those achieved in a previous CALGB trial with oral cyclophosphamide as a single agent, although severe myelotoxicity was increased to approximately 60% of patients from less than 10% with the single-agent therapy. The combination of alpha interferon and cyclophosphamide administered in this fashion is safe when peripheral counts are carefully monitored. Randomized studies of this regimen in comparison to oral cyclophosphamide are currently in progress.

Treatment of unresectable hepatocellular carcinoma with a combination of human recombinant alpha-2b interferon and doxorubicin: results of a pilot study

Based on the in vitro and in vivo potentiation of the cytotoxic activity of chemotherapeutic agents by the interferons, a pilot study combining human recombinant alpha-2b interferon (IFN) and doxorubicin was conducted for the treatment of unresectable, histologically proven hepatocellular carcinoma. Between March 1988 and May 1990, 21 patients (median age: 60 years, range: 29-76) entered the study. The dose of doxorubicin was fixed at 35 mg/m2, every 3 weeks. The dose of alpha-2b IFN was 6 million U/m2 per day, 5 days a week. 3 patients (14%) obtained a partial response lasting 11, 16 and 30 months, and 1 had a stable disease during 8 months. The other 17 patients died within a median survival time of 4 months. All patients experienced flu-like symptoms. 7 patients experienced WHO grade III-IV haematological toxicity. We conclude that the association of alpha-2b IFN and doxorubicin is feasible, with respect to the use of doxorubicin at an inferior dose level than the same agent used without IFN. The response rate is comparable to that observed with doxorubicin used alone. Further phase I studies and randomised trials are required to confirm the role of this regimen in the treatment of unresectable hepatocellular carcinoma.

Interferon alfa combined with cytotoxic chemotherapy for patients with non-Hodgkin's lymphoma

BACKGROUND

Interferon alfa has been found to be effective as an antitumor agent (with a response rate of 30 percent) in patients with low-grade non-Hodgkin's lymphoma, but its effectiveness in those with intermediate-grade non-Hodgkin's lymphoma has been less adequately tested. In a prospective randomized study we evaluated the effectiveness of adding interferon alfa to cytotoxic chemotherapy in patients with clinically aggressive, low-grade non-Hodgkin's lymphoma and certain histologic variants of intermediate-grade non-Hodgkin's lymphoma, not including diffuse histiocytic lymphoma.

METHODS

The patients were randomly assigned to a regimen of cyclophosphamide, vincristine, prednisone, and doxorubicin or to this regimen combined with recombinant interferon alfa. Treatment was administered every four weeks, for 8 to 10 cycles.

RESULTS

The two regimens produced comparable objective responses, but the regimen including interferon had a greater effect in prolonging the time to treatment failure (P < 0.001) and the duration of complete response (P = 0.03). Interferon alfa also had a greater effect on overall survival (P = 0.014) when the results were adjusted for important covariates.

CONCLUSIONS

Interferon alfa, when added to a four-drug doxorubicin-based chemotherapy regimen, is an effective antitumor agent in patients with clinically aggressive low-grade or intermediate-grade non-Hodgkin's lymphoma.

Interferon alfa-2b in addition to chlorambucil in the treatment of follicular lymphoma: preliminary results of a randomized trial in progress

One hundred and twenty four patients with follicular lymphoma (32 with Stage III and 92 with Stage IV disease) have been randomized to receive chlorambucil alone or chlorambucil plus interferon alfa-2b. Responding patients are then randomized to receive either interferon alfa-2b maintenance therapy for up to 12 months or no further treatment. One hundred and eight patients are evaluable for response, the remainder are still receiving initial therapy. Clinical remission (complete or good partial remission) was achieved in 42/59 (71%) patients receiving chlorambucil alone and in 27/49 (55%) patients receiving the combination (P = NS). Preliminary analysis of remission duration shows a trend in favour of those patients receiving interferon throughout (P = 0.02). There is no significant difference between the groups in terms of survival, at a median follow up of 2.5 years. Interferon-associated toxicity was minor in most patients but led to discontinuation of therapy in six cases. Larger trials with longer follow-up periods are needed to confirm the beneficial role of interferon in the treatment of follicular lymphoma.

Effects of interferons and other cytokines on tumors in animals: a review

The term cytokine describes a group of protein cell regulators involved in the control of cell growth and differentiation in embryogenesis, immunity and inflammation. They are of low molecular weight, are produced locally, and act in an autocrine or paracrine manner. In the past decade their use as cancer therapy has become a reality. Thirty years ago mice were treated with the antiviral protein interferon (IFN) which not only produced a reduction in the incidence of virus-induced tumors but also slowed the development of transplantable tumors. This was one of the first indications that cytokines can be negative regulators of cell growth. Here we outline current knowledge of the actions of IFNs and other cytokines in animal models, and draw parallels with clinical trials to illustrate the invaluable nature of this preclinical and mechanistic work.

New approaches to the treatment of follicular lymphoma

The major avenues of clinical research into the treatment of follicular lymphoma, 'more, if so when?', interferon therapy, and antibody therapy, have been presented in the light of present knowledge about the clinical course of the disease. They must be seen within the context of the current philosophical approach to the illness, and the economic climate which prevails, at a time when new drugs, for example fludarabine (Leiby et al, 1987; Reman et al, 1988; Whelan et al, 1991), are showing promise, and differentiating agents are being tested in remission (Cunningham et al, 1985). There can be little doubt that the objective of future research should be to eliminate the disease altogether at the time of initial presentation, since patients entering remission and never having a recurrence have a far greater probability of longevity than those in whom recurrences occur (Lister, 1991). There can also be little doubt that when lymphoma is present and causing symptoms, treatment should be given, since survival is longer for those in whom a response is achieved, at least at presentation, and at first recurrence (Lister, 1991). Since the latter is sadly the reality for the majority, improving treatment at the time of recurrence must also be a priority. Time will tell whether any of the options presently under investigation will be appropriate at all, and if so when. It is certainly the case that some of them will be entirely inappropriate for some patients, because the risk of toxicity will outweigh the potential benefit, especially for the elderly. Further careful identification of prognostic variables may allow for individualization of therapy. It would be comforting to know that the newly found molecular marker of the disease would help us. Its absence may do--but its presence certainly does not, since t(14;18) containing cells may seemingly be present for many years of clinical normality (Price et al, 1991, in press). The challenge to find the right treatment at the right time--or perhaps to identify the 'right patient' for the therapy continues.

Interferon alpha in lymphoma

A number of studies are currently in progress to evaluate the use of interferon alpha, alone and in combination with conventional chemotherapy in patients with follicular lymphoma. The background to these is reviewed, together with currently available data about the potential role of interferon alpha in cutaneous T cell lymphoma.

Local immunotherapy (beta-IFN) and systemic chemotherapy in primary glial tumors

Dosage and schedules for the treatment of malignant glial tumors using IFN (interferon) are still uncertain and controversial. In this study we give the preliminary results of treatment in 28 patients with glioblastoma multiforme (GBM). 6 patients were treated with local injection of beta-IFN through an Ommaya reservoir; 4 patients with beta-IFN followed by systemic chemotherapy (Cisplatin + Etoposide), and 18 patients with chemotherapy only. Two end points were evaluated: 1) Whether or not the patients responded to treatment. 2) Length of Time to Tumor Progression (TTP) after surgery. We found that IFN alone was ineffective. Results were improved when local immunotherapy was associated with systemic chemotherapy. New drugs and investigation of possible pharmacological synergism are needed.

Interferon-alpha 2b in the treatment of follicular lymphoma: preliminary results of a trial in progress

Since 1985 the combination of chlorambucil (10 mg daily, initially for six weeks, then alternating fortnights for 12 weeks) and interferon-alpha 2b (Schering-Plough; 2 x 10(6) U/m2 three times weekly by subcutaneous injection for 18 weeks) has been compared in a randomised trial with chlorambucil alone in previously untreated patients with stage III or IV follicular lymphoma. Responding patients have subsequently been randomised to receive maintenance interferon-alpha 2b or no further treatment. Of the 124 treated patients, 108 are evaluable for response with a median follow-up of 30 months. The major toxicity was myelosuppression which was more frequent with chlorambucil and IFN alpha 2b in combination than with chlorambucil alone (P less than 0.01). There was no treatment-related mortality. Actuarial survival at three years is 75% for all patients, regardless of therapy. There was no significant difference in response rate according to initial therapy. For the 60 patients achieving a good response to initial therapy who have entered the second part of the trial, there has been a significant prolongation of remission duration in favour of maintenance IFN-alpha 2b (median not yet reached versus two years for the 'no treatment' arm, P less than 0.015). Fewest relapses have been seen in patients who received IFN-alpha 2b throughout. Accrual to this trial continues; this preliminary analysis indicates that maintenance IFN-alpha 2b may extend remission duration in follicular lymphoma.

Sensitivity of chronic myeloid leukemia hemopoietic progenitors to PTT-119 in combination with human recombinant interferon alpha and gamma

PTT-119, a new synthetic alkylating compound, has shown a marked "in vitro" inhibitory effect on chronic myeloid leukemia (CML) granulo-monocytic precursors (CFU-GM) at doses greater than 5 micrograms/ml. Based on previous experiences of synergistic associations between alkylating drugs and biological modifiers, we tested the effects of low doses of PTT-119 (from 0.1 to 1 microgram/ml) in concert with alpha, gamma, or alpha + gamma interferons and compared to IFNs alone, in order to investigate an alternative choice for treatment of CML patients in chronic phase. Our results showed a significantly higher CFU-GM cloning inhibition after addition of 100 or 1,000 U/ml of alpha IFN to 0.1 microgram/ml PTT-119 (from 39.6% +/- 26.6 SD to 80.7% +/- 10 SD and 91.5% +/- 8 SD, respectively), while gamma IFN resulted in only a slight increase in colony growth inhibition when compared to the drug used alone. The association of alpha plus gamma IFN coupled with PTT-119 treatment did not significantly improve the results observed after exposure of leukemic progenitors to PTT-119 and alpha IFN alone. We conclude that a combined treatment with PTT-119 and IFN is probably worth testing both for purging methods before autologous bone marrow transplantation and for in vivo administration in chronic myeloid leukemia.

Cyclophosphamide-dependent lymph node modification in lymph node metastasis of MM48 tumor cells in syngeneic mice

We investigated the role of immunosuppressive activity induced in the regional lymph nodes (RLN, popliteal lymph nodes) in the establishment of lymph node metastasis by cyclophosphamide (CY) administration. The CY treatment led to the elimination of suppressive activity with the appearance of positive immune responses, and the inhibition of lymph node metastasis of MM48 tumor cells. In CY-treated mice, the removal of RLN together with the primary tumor lowered the survival rate compared with the mice in which the RLN remained intact. During 4 days after primary tumor resection, the proliferation of tumor cells in the RLN was significantly decreased in CY-treated mice. These results suggested that the induction of suppressive activity in the lymph node is closely associated with the establishment of lymph node metastasis.

Recombinant leukocyte A interferon with doxorubicin. A phase I study in advanced solid neoplasms and implications for hepatocellular carcinoma

A pilot study was performed on seven patients with advanced solid neoplasms. They received recombinant leukocyte interferon A (rIFN-alpha A) 12 X 10(6) U/m2 intramuscularly daily for 5 days plus doxorubicin, 25 mg/m2 IV on day 3 of each monthly cycle (Roferon-A, Hoffman-LaRoche, Nutley, NJ). Because of side effects, the dose was not increased above the initial level. There was a striking partial response of biopsy-confirmed hepatocellular carcinoma for 6+ months along with a decrease in alpha-fetoprotein from 39,000 to 202 ng/mL. The doxorubicin dose is approximately 33% to 42% of the typical single-agent dose, thus suggesting that the clinical toxicity from these two agents is additive.

Overview of preclinical and clinical studies of interferon alfa-2b in combination with cytotoxic drugs

Both in vitro and in vivo studies have demonstrated antiproliferative effects of interferon alfa-2b (Intron A; Schering-Plough) when tested with human tumor cells. A clonogenic assay has been widely used to determine its direct antiproliferative effects on human tumor cells in vitro using colony reduction as a reproducible endpoint. As a single agent, interferon alfa-2b shows maximum tumor cell colony reduction when used in high concentrations with continuous cell exposure. Short-term exposure to interferon alfa-2b does not produce significant tumor cell colony reduction. Clonogenic assays have also been used to test combinations of interferon alfa-2b with cytotoxic drugs. Variations in drug scheduling, sequencing and concentrations have indicated the best combinations which maximize tumor cell colony reduction. Combinations of interferon alfa-2b with doxorubicin, cisplatin, vinblastine, melphalan and cyclophosphamide have been shown to have at least additive and occasionally synergistic antiproliferative effects. In clinical trials, optimal pairs of agents have been identified frequently combining either doxorubicin, cisplatin or vinblastine with interferon alfa-2b. Pretreatment with interferon alfa-2b has been adopted from in vitro studies and applied to most clinical trials. One study has enrolled 135 patients having a variety of advanced or recurrent solid tumor types, using a schema which combines interferon alfa-2b and doxorubicin administration, both given on a weekly basis for three weeks, followed by treatments every two weeks in responding patients. Clinical responses have been seen using this regimen in patients with ovarian, cervical, colorectal and pancreatic carcinomas and in one lymphoma patient. Another study has been designed combining melphalan, prednisone and interferon alfa-2b for the treatment of patients with relapsing multiple myeloma. This is also based upon preclinical data. New methods of administration are being studied giving interferon alfa-2b as a single agent or in combination with cisplatin by the intraperitoneal route to patients with relapsing ovarian carcinomas limited to the peritoneal cavity. This method can maximize both the levels of interferon alfa-2b as well as the tumor cell exposure time.

A phase II study of human rDNA alpha-2 interferon in patients with low grade non-Hodgkin's lymphoma

Thirty-five patients with a diagnosis of non-Hodgkin's lymphoma of low histological grade were treated with 2 X 10(6)/m2 of human rDNA alpha 2 IFN-a2 by subcutaneous injection. Treatment was continued until progressive disease was documented or one year of therapy had been given. None of the patients had to stop treatment because of toxicity and no treatment delays or suspensions of therapy were necessary as a consequence of myelosuppression. Thirty four patients were evaluable and seventeen (50%) obtained an objective response (2 CR, 15 PR) with a median duration of eleven months. Sixteen patients were untreated prior to receiving interferon but were felt to need some form of therapy rather than be suitable for a watch policy. Eleven of these patients responded (69%) with 95% confidence limits lying between 41% and 89%. No other pretreatment factors appeared to affect the likelihood of response. Single agent IFN-alpha 2 has significant activity in the low grade non-Hodgkin's lymphomata and warrants further investigation in this disease.

Synergistic antiproliferative effect of human interferons in combination with mismatched double-stranded RNA on human tumor cells

Four human tumor cell lines were studied for their response to antiproliferative effects of various interferons (IFNs) alone and in combination with the novel mismatched dsRNA, r(I)n r(C12,U)n (Ampligen). RT4 cells (bladder carcinoma) were resistant to Ampligen alone, while A2182 (lung carcinoma), HT 1080 C14 (fibrosarcoma) and RT112 (bladder carcinoma) cells were inhibited in a dose-dependent manner. In contrast, RT4 cells were sensitive to the antitumor effects of IFNs as were HT1080 C14 and RT112 cells, while A2182 cells were resistant. In 3 of 4 cell lines, the recombinant IFNs were less effective than the corresponding natural IFNs when compared by analysis of variance on an IRU/ml basis over a range of concentrations. In all cell lines, a synergistic antiproliferative effect was seen with all IFN preparations studied in combination with Ampligen, as calculated by the isobole method according to Berenbaum (1981). The antiproliferative effect of IFN was potentiated greater than 3.3- to greater than 250-fold, depending on the cell lines, IFN, and concentrations used. Varying the concentration of beta ser-IFN while holding the Ampligen concentration constant gave synergy at all of the physiologically achievable concentrations tested in RT4 cells. These results indicate that: Ampligen worked synergistically with all IFNs in all cell lines studied; growth inhibition of cells resistant to IFNs can be potentiated by low doses of Ampligen; the antiproliferative effect of IFNs can be potentiated by Ampligen in Ampligen-resistant cells; and Ampligen may work by a mechanism other than, or in addition to, the induction of IFNs.

In vitro chemosensitivity tests on human tumor xenografts by clonogenic assay: the combined use of mitomycin C with alpha-interferon or gamma-interferon

Using the human tumor clonogenic assay technique, the effects of Mitomycin C plus either alpha-interferon or gamma-interferon were studied against five human tumor xenografts serially transplanted into nude mice (three gastric and two colon cancers). When the survival fraction found with the drug combination was smaller than the multiplication of survival fractions with either drug alone, the combined effect was defined as synergism. Similarly, antagonistic effect was defined when the survival fraction of drug combination was larger than the larger one observed in either interferon or Mitomycin C alone. Four out of five human tumor xenografts (three gastric and one colon cancers) showed synergistic effects in combination of alpha-interferon with Mitomycin C. Though two gastric cancer xenografts exhibited synergistic effects in combination of gamma-interferon with Mitomycin C, antagonistic effects, which was not found in combination of alpha-interferon with Mitomycin C, were observed in one gastric cancer and one colon cancer xenografts.

Combined effect of 5-fluorouracil and interferon on experimental liver metastases of rat colon carcinoma

The combined effect of 5-Fluorouracil (5-Fu) and partially purified rat interferon (RIFN) was assessed on experimental liver metastases of a transplantable colon tumor in rats. Treatment was given for 8 weeks and started 1 week after inoculation into the portal vein of 5 X 10(5) tumor cells. Administration of 10(5) units RIFN/kg/day for 7 days, in alternate weeks, had no effect on the number or size of liver metastases as judged by laparotomy on days 30 and 50, whereas treatment with 5-Fu at a dose of 15 mg/kg once a week had a moderate but significant inhibitory influence. The combined administration of RIFN and 5-Fu led to earlier development of liver metastases than in the control group. There was no difference in survival time between the control group and the RIFN-treated group; all animals died within 20 weeks after tumor cell injection. However, three of eight animals in the 5-Fu group and, surprisingly, four of ten animals in the RIFN + 5-Fu group survived for more than 20 weeks and were found to be free of tumor when inspected after 175 days. The data indicate that 5-Fu, given either alone or combined with RIFN, is effective in about 40% of cases, and further suggest that RIFN has tumor-enhancing properties in those animals in which treatment with 5-Fu has no antitumor effect.

The combined effect of interferon-beta and cytostatic drugs on human tumor cell lines in vitro

Three human tumor cell lines (one osteosarcoma and two neuroblastoma lines) were assessed for combined interferon-beta (IFN-beta)/chemotherapeutic drug antigrowth effect under in vitro conditions. Two different methods to measure this effect were used: colony formation in soft agar and counting of cells growing as monolayers. The cells were incubated with a chemotherapeutic drug (adriamycin, dacarbazine, actinomycin D, cis-platinum, methotrexate, VP-16-213, or vincristine) at relevant concentrations for 1 h, washed twice, and incubated with IFN-beta in concentrations ranging from 100 to 1000 IU for continuous exposure. All combinations resulted in an additive or synergistic combination effect with one exception: methotrexate/IFN-beta in the monolayer method after 1 week, a combination which was additive after 3 weeks however. The combinations VP-16-213/IFN-beta and cis-platinum/IFN-beta produced the most pronounced synergistic effects. A statistical evaluation of the null hypothesis for additivity was done. These results provide a rationale for designing clinical studies combining IFN-beta with current chemotherapeutic drugs.

Progress toward therapeutic application of interferons, 1979-1983

Interferons differ chemically and biologically from other modalities of cancer treatment. They are proteins that inhibit viral replication, influence subcellular processes, slow cellular proliferation, affect cell differentiation, and modulate immune responses. These regulatory effects on cell function undoubtedly underlie the effects of interferons in malignant disease. As a result of efforts by academia, industry, governments, and organizations such as the American Cancer Society, significant progress has been made over the past 5 years in elucidating structure, improving production, and defining clinical applications of interferons for both virus and malignant disease.

In vitro and in vivo studies on potentiation of cytotoxic effects of anticancer drugs or cobalt 60 gamma ray by interferon on human neoplastic cells

A possibility that interferon may potentiate the cytotoxic effects of anticancer drugs or 60Co gamma ray on human neoplastic cells was studied by in vitro and in vivo experimental procedures. The human neoplastic cells used were HeLa (uterine cervical cancer) and WI-38 CT-1 (embryonic lung fibroblasts transformed in culture by 60Co gamma ray) cells. As normal human cells, WI-38 cells were used. Interferon was a preparation of beta-type produced by human fibroblasts. The cytotoxicity was determined by colony formation for in vitro experiments and by tumor growth for animal experiments. Of 17 anticancer drugs, the cytotoxic effects of six drugs, namely, peplomycin, bleomycin, aclacinomycin, cisplatin, 5-fluorouracil (5-FU), and Adriamycin (doxorubicin) were potentiated by concomitant application of interferon. The cytolethal effects of 60Co gamma ray were also enhanced by interferon. The growth of tumor induced by transplantation of HeLa cells into a nude mouse was remarkably reduced by combination therapy of interferon and 5-FU. The current results indicate a possibility that combined therapy of certain types of anticancer drugs or 60Co gamma ray with interferon may be effective in treatment of cancer patients.

In vitro studies on potentiation of cytotoxic effects of anticancer drugs by interferon on a human neoplastic cell line (HeLa)

Experiments were performed to ascertain whether the antitumor effect of various anticancer drugs might be enhanced by interferon, using cultures of HeLa cells originating from a human carcinoma of the uterine cervix. The effects of drugs were assessed by counting cell colonies formed in culture. The drugs studied included 4 metabolic antagonists: cytosine arabinoside (Ara-C), 5-fluorouracil (5-FU), 6-mercaptopurine (6-MP) and methotrexate (MTX), 7 antibiotics: aclacinomycin (ACM), adriamycin (ADM), actinomycin D (ACD), cycloheximide, mitomycin C (MMC), peplomycin (PEP) and puromycin; 2 alkylating agents: nimustine hydrochloride (ACNU) and melphalan, and 3 other drugs, vincristine (VCR), cisplatin (CDDP) and hydroxyurea (HU). Interferon was a preparation of the beta-type produced by human fibroblasts. A specific additive or synergistic potentiation of the cytotoxic effect by concomitant application of interferon was observed with PEP, ACNU, ACM, CDDP, 5-FU and ADM; the drug concentration given a 50% inhibition of cell growth was reduced by one-half or more in cultures with the combination of interferon and these drugs. The treatment of cells with interferon alone caused only 10-30% inhibition of cell proliferation.

Interactions of human leukocyte interferon with vinca alkaloids and other chemotherapeutic agents against human tumors in clonogenic assay

Purified human leukocyte interferon produced by recombinant techniques (IFN-alpha A) was tested in vitro with chemotherapeutic drugs, vinblastine (VLB), vincristine (VCR), vindesine (VDS), vinzolidine (VZL), cis-platinum (PLAT), doxorubicin (DOXO), etoposide (VP-16), and melphalan (MEL). The activity of these agents alone or in combination was tested against various human tumor cell lines, using a modified soft agar clonogenic assay. Three human tumor cell lines (myeloma, RPMI 8226; breast, MCF-7; and colon, WiDR) showed sensitivity to these agents at clinically achievable drug concentrations. Statistically significant synergistic activity against in vitro colony formation was observed with the combination of VLB and IFN-alpha A. An additive or sub-additive effect was usually observed with the other agents tested. Continuous exposure of the 8226 myeloma cell line to both IFN-alpha A and PLAT showed evidence of a more significant potentiation. It is hypothesized that the synergistic effect observed between VLB and IFN-alpha A is due to some of their common mechanisms of action.

Effect of treatment with interferon and cyclophosphamide on the growth of a spontaneous liposarcoma in rats

A spontaneous non-immunogenic transplantable liposarcoma in BN rats was found to be sensitive to the antitumor effects of rat fibroblast interferon (RIF) when it was administered from the day of tumor implantation onwards. Treatment with RIF starting at 7 days after implantation was not effective. Tumor growth was markedly inhibited by cyclophosphamide (Cyclo). At the time and dose schedules used, Cyclo was more effective than RIF. When the growth of the tumor was inhibited by Cyclo, subsequent treatment with RIF did not lead to an additional retardation of tumor growth. Administration of RIF interfered with the beneficial effect of Cyclo when both agents were given concomitantly. RIF and Cyclo gave similar results to those obtained with RIF alone and these were inferior to those obtained with Cyclo alone.

Interferon and cis-DDP: combination chemotherapy for P388 leukemia in CDF1 mice

CDF1 mice were implanted with 10(6) P388 leukemia cells. One day postimplantation, when interferon (IFN) therapy was begun, the tumor burden was ca. 4.8 X 10(6) cells. Therapy consisted of nine consecutive daily intraperitoneal (i.p.) injections of 10(6) units of Ehrlich ascites tumor cell IFN (specific activity 5 X 10(7) IU/mg). The median life span for control animals was 10.0 days versus 18.5 days for the treated animals. It was estimated that about 2 X 10(6) viable P388 cells were present on Day 9 when therapy was discontinued. There was no evidence of toxicity in animals receiving 10(6) units of IFN/day for nine consecutive days. In a separate experiment, control animals challenged as above had a median life span of 9.5 days of versus 15 days for animals receiving 10(6) units of IFN qd on Days 2-10. A third group of animals receiving a single injection of cis-DDP on Day 1 had a median survival of 18.5 days, while a fourth group receiving both cis-DDP on Day 1 and subsequent treatment with IFN survived 26 days. The results are discussed in terms of impact on tumor cell population.