rIFN-alpha 2a Research Articles

No Development of Neutralizing Antibodies Against Recombinant Interferon-Alpha in Ph-Negative Myeloproliferative Neoplasms - a Prospective Study

BackgroundTreatment of Philadelphia chromosome negative chronic myeloproliferative neoplasms (MPNs) with recombinant pegylated interferon alpha2a/b (rIFN-alpha) has proven effective. It is well known that prolonged therapy with recombinant type 1 interferons (IFN-alpha and IFN-beta) may induce neutralizing antibodies (nAbs) against the drug leading to treatment failure. Most data on type 1 IFN immunogenicity are available from studies of patients with multiple sclerosis treated with rIFN-beta, and patients with hepatitis C treated with rIFN-alpha. A few reports have demonstrated nAbs in MPN patients not responding adequately to rIFN-alpha treatment, but the phenomenon has not been thoroughly investigated in MPNs.Patients and MethodsNewly diagnosed patients with MPNs enrolled in the Danish multicenter trial - DALIAH (Low-dose rIFN-alpha versus Hydroxyurea in The Treatment of Ph-Negative MPNs) were included. Patients were randomized to treatment with either rIFN-alpha 2a or 2b at a starting dose of 45 and 35 mikrograms once weekly, respectively. The occurrence of neutralizing Abs (nAbs) against rIFN-alpha was investigated at baseline, month 12 and month 24 by reporter gene assays (iLiteTM alphabeta and iLiteTM antialpha, Biomonitor A/S, Copenhagen, Denmark). JAK2 V617F quantitative mutation analyses were performed as previously described (Larsen TS, BJH 2007). Statistical analyses were performed using STATA version 9.0.ResultsNinety-two patients on sustained treatment with rIFN-alpha2a (n=48) and rIFN-alpha2b (n=44) for 12 months were analyzed for this study. Forty-five patients had ET, 39 patients had PV and 8 patients had proliferative PMF. Thirty-six out of 39 (92%) PV patients, 22 out of 45 (49%) ET patients and 4 out of 8 (50%) PMF patients were JAK2V617F mutated. Hematological responses at 12 months: ET: 67% CR, 29 % PR; PV: 64% CR, 31% PR (ELN 2009 criteria); PMF: 50% had at least a minor response (EUMNET).The median serum concentration of bioactive IFN-alpha at 12 months was 12,4 (range <2,4-86,4) and 2,6 (range <2,4-12,8) IU/mL serum, for patients treated with rIFN-alpha 2a and -2b respectively. No significant association between hematological or molecular response and serum IFN-alpha activity was found. Serum from 92 patients was analyzed at 12 months and 33 patients were analyzed at both 12 and 24 months and no occurrence of nAbs was seen during treatment. Twenty-four patients had pre-treatment levels of IFN nAbs measured. Notably, one patient was tested positive for the presence of nAbs before rIFN-alpha exposure. This autoAb-positive patient remained positive throughout the study and has shown low IFN serum activity (< 2,4 IU/mL) and only partial hematological and molecular response after 24 months of treatment.ConclusionsDevelopment of nAbs in MPN patients completing treatment for 12 months with rIFN-alpha seems exceedingly rare as no patients, neither complete responders nor patients not meeting criteria for complete hematological remission developed nAbs after 12 (24) months of therapy. Its apparent rarity does not justify a routine investigation of nAbs in patients not responding to rIFN-alpha treatment. There was no significant correlation between serum concentration of rIFN-alpha 2a and -2b and clinical or molecular responses. The intriguing finding that one of 24 patients had pre-existing cross reacting nAbs against rIFN-alpha 2a and 2b before commencing rIFN-alpha treatment is interesting and was associated with an insufficient response. DisclosuresOff Label Use: Recombinant interferon-alpha 2a and -2b in the treatment of chronic Philadelphia-negative myeloproliferative neoplasms.. El Fassi:Novartis Denmark: Honoraria, Other: Have conducted an educational session for Novartis Denmark, regarding MPNs and ruxolitinib, for this a honorarium was received.. Bjerrum:Bristoll Myers Squibb, Novartis and Pfizer: Other: educational activities. Hasselbalch:Novartis: Research Funding. Bendtzen:Pfizer: Honoraria; Eurodiagnostica AB: Equity Ownership; Novo-Nordisk: Equity Ownership.

Characterization of anti-interferon-alpha antibodies appearing during recombinant interferon-alpha 2a treatment.

Patients with malignant midgut carcinoid tumours received recombinant interferon-alpha 2a (rIFN-alpha 2a) or rIFN-alpha 2a and chemotherapy (streptozocin and doxorubicin) for 6 months, and then rIFN-alpha 2a alone. Antibodies, mainly of IgG type, binding to rIFN-alpha 2a developed in nine of 22 patients (41%), as determined by immunoassay. In seven patients, antibodies also neutralized the biologic (anti-viral) activity of rIFN-alpha 2a. Anti-IFN-alpha 2a antibodies were equally frequent in both sexes and treatment groups, but were not observed in those patients (n = 8) that had previously received other types of IFN. Antibodies appeared after a median of 6 months of rIFN-alpha 2a treatment and had a median duration of 6 months. The anti-IFN-alpha 2a antibody titres declined with time with no obvious relation to change of therapy, also during continued IFN-alpha 2a treatment. High titres of neutralizing antibodies appeared to impair anti-tumoural effects in individual potential responders. Anti-IFN-alpha 2a antibodies further examined in six patients bound to native IFN-alpha subtypes present in both allogenic and autologous leucocyte IFN-alpha. Such autoantibodies neutralized the biologic activity of autologous IFN-alpha in two patients, and in a third were partially neutralizing.

Neutralizing antibodies to interferon (IFN) α-2a and IFN β-1a or IFN β-1b in MS are not cross-reactive

Sera from patients with MS treated with recombinant interferon (rIFN) alpha-2a, rIFNbeta-1a, or rIFNbeta-1b were analyzed for cross-reacting neutralizing antibodies (NAB). Because cross-reactivity was not found, switching treatment from rIFNbeta-1a or rIFNbeta-1b to rIFNalpha-2a might provide a secondary treatment response in patients with NAB to rIFNbeta-1a or rIFNbeta-1b. A positive treatment response also might be achieved by switching NAB rIFNalpha-2a-positive patients to rIFNbeta-1a or rIFNbeta-1b.

High avidity IFN-neutralizing antibodies in pharmaceutically prepared human IgG.

This paper demonstrates and characterizes naturally occurring antibodies to interferon (IFN) in human IgG preparations. In vitro neutralization of the antiviral effect of IFN alpha and IFN beta, but not IFN gamma, was observed in 12 of 15 normal IgG preparations. The neutralizing capacity was higher against rIFN alpha 2A and rIFN alpha 2C than against lymphoblastoid IFN alpha and IFN beta. Frühsommer meningoencephalitis hyperimmune IgG and hepatitis-B hyperimmune IgG showed potent neutralization, whereas anti-rhesus D-, anti-rabies-, and anti-tetanus IgG showed weak neutralization. Saturable binding of 125I-rIFN alpha 2A was demonstrated only in those IgG preparations found to neutralize the antiviral effect of IFN. Significant correlation between IFN binding and neutralization capacity was observed. The antibodies bound with Fab to rIFN alpha 2A with an avidity of approximately 30 pM; the majority was of the IgG1 subclass. Maximum binding capacity was 490 pg rIFN alpha 2A/mg IgG. Cross-binding of rIFN alpha 2C, lyIFN alpha N1 and IFN beta occurred with 10 and 100-200 times lower activities than that of rIFN alpha 2A. There was no cross-binding with rIFN gamma or rIL-6. IgG preparations containing anti-IFN antibodies blocked the binding of 125I-rIFN alpha 2A to A549 cells. In conclusion, pharmaceutically prepared human IgG preparations contain variable but significant levels of high-avidity IFN alpha and IFN beta neutralizing antibodies.

Multicenter randomized trial of dacarbazine alone or in combination with two different doses and schedules of interferon alfa-2a in the treatment of advanced melanoma.

Some phase II studies have suggested that the combination of interferons (IFNs) with dacarbazine (DTIC) in the treatment of malignant melanoma (MM) increases the antitumor activity of DTIC alone. In an attempt to confirm this hypothesis, a randomized study was performed with the further intent of observing whether low doses of recombinant interferon alfa-2a (rIFN alpha 2a) could be as effective as intermediate doses. Two hundred sixty-six patients were randomized onto three different treatment arms: DTIC 800 mg/m2 intravenously (IV) days 1 and 21; DTIC plus rIFN alpha 2a 9 mIU intramuscularly (IM) daily; and DTIC plus rIFN alpha 2a 3 mIU IM three times per week. Major prognostic factors were well balanced among the three arms. Chemotherapy was administered for a maximum of eight cycles. After 6 months of therapy, rIFN alpha 2a was continued until disease progression at 3 mIU three times per week in responding patients who had received the combined treatment. The percentage of objective responses did not differ among the three groups (20%, 28%, and 23%, respectively), although a significant prolongation of response duration was observed when rIFN alpha 2a was added to DTIC (2.6 v 8.4 v 5.5 months, respectively). However, this improvement in response duration did not translate into an amelioration of overall survival. The addition of rIFN alpha 2a led to the onset of flu-like syndrome, but in no case was it necessary to withdraw the treatment program and no toxic deaths or life-threatening toxicities were reported. In this study, rIFN alpha 2a significantly prolonged response duration, whereas no effects on response rate and survival were observed; rIFN alpha 2a 3 mIU appeared to be equally effective and better tolerated than 9 mIU.

Interferon (IFN)-alpha 2 genotype analysis of Chinese chronic hepatitis B patients undergoing recombinant IFN-alpha 2a therapy.

Sixteen Chinese chronic hepatitis B virus (HBV)-infected patients were treated with recombinant interferon-alpha 2a (rIFN-alpha 2a). Of these, 8 made a response to IFN, with titers of neutralizing antibody of 141-4525 as determined by an antiviral neutralization bioassay. To determine whether the immunogenicity of the IFN was directly linked to the patients' genotype, their genomic DNA was analyzed for the presence of the human IFN-alpha 2a gene. None of the patients possessed the gene for IFN-alpha 2a, but only 50% developed neutralizing antibodies. The hypothesis, therefore, of a direct link between antibody formation and genotype cannot be sustained. Alternative explanations of the immunogenicity of IFN-alpha 2a must be sought.

Treatment with recombinant alpha-interferon of chronic hepatitis C in anti-HIV-positive patients.

A pilot study of chronic hepatitis C treatment was conducted in 14 patients (13 had chronic active hepatitis and 1 had liver cirrhosis). All patients were asymptomatic for the human immunodeficiency virus (HIV) type 1 (mean CD4 count of 584 +/- 283 cells/mm3). Patients received 9 MU rIFN-alpha 2A per day for three months. After this, patients received 9 MU three times weekly for three months, 6 MU for another three months on the same protocol, and finally 3 MU again three times weekly for the last three months. After the first month of ALT treatment in 9 patients (64%) returned to normal; a significant decrease in ALT levels was observed with respect to the pretreatment values (mean of 42 IU/l, range 15-75 vs 152 IU/l, range 69-355; P < 0.01). Of the 9 patients who completed the treatment period, 5 had a complete response, and 4 of these 5 continued with normal ALT values during follow-up (sustained response) while the other patient relapsed within one month after cessation of therapy. The remaining 4 patients were non-responders (including one case with a break-through of the response). HCV-RNA was not detectable in 3 of the 5 responders at the end of therapy while during follow-up viral RNA became undetectable in the other 2 patients. 2/4 non-responder patients had detectable HCV-RNA during follow-up. Liver histology improved in all the patients. No changes were observed in the immunological status or HIV infection.

Immunological and clinical effects of intramuscular rIFN alpha-2a and low dose subcutaneous rIL-2 in patients with advanced malignant melanoma.

Fifteen patients with tumour recurrence following radical surgical excision of malignant melanoma were treated with a combination of interferon alpha-2a (rIFN alpha-2a) and interleukin-2 (rIL-2). Immunological monitoring (performed prior to therapy and on days 7, 21, and 28, of each course of treatment) showed significant changes of several parameters after rIFN alpha-2a and rIL-2 administration. A significant increase in cells expressing CD16 (cells bearing Fc receptor), CD25 (cells bearing IL-2 receptor), and CD56 (NK cells, activated lymphocytes), as well in levels of soluble IL-2 receptor, beta 2-microglobulin and neopterin was observed. Immunological changes were closely related to the injection of the biological agent and were more relevant during the first than the second cycle of treatment. rIFN alpha-2a and rIL-2 exerted a clear synergistic activity on the same immunological parameters. No major response was seen with the present approach: four subjects showed rapid progression of decrease during the first month of therapy, while of 11 patients who completed two courses of treatment, only five were considered in stable disease. In conclusion, our results suggest that a combination of rIFN alpha-2a and rIL-2, at dosages and schedules, used in this trial, was well-tolerated and immunologically active, but was clinically ineffective in the management of advanced melanoma.

Intralesional Alpha Interferon Therapy in Papillary Superficial Transitional Cell Carcinoma of the Bladder A Pilot Study

The tolerability, toxicity and therapeutic efficacy of recombinant interferon alpha-2a (rIFN alpha-2a), administered by intralesional injection, were evaluated in 15 patients with papillary superficial transitional cell carcinoma of the bladder, rIFN alpha-2a was delivered endoscopically in a single weekly dose of 3 x 10(6) IU for 4 weeks (total 12 x 10(6) IU). Transurethral resection of residual tumours was then performed. The response to treatment was assessed according to ultrasonographic, endoscopic and pathological findings. One patient achieved complete remission, 6 partial remission, 6 minor remission and 2 stabilisation of disease. All patients completed the course of treatment. A mild, transient, flu-like syndrome was documented after every injection. Immunological findings suggest that the antitumour effects of rIFN alpha 2a are not mediated through the immune system.

Antibodies developing against a single recombinant interferon protein may neutralize many other interferon-alpha subtypes.

Three hepatitis C patients out of 15 who received recombinant interferon-alpha 2a (rIFN-alpha 2a) therapy developed high levels of neutralizing antibody coincident with clinical relapse. On analysis, antibodies in their sera were found to also produce some neutralization of lymphoblastoid IFN. Purified lymphoblastoid IFN was separated chromatographically into 10 fractions, each containing one or two IFN-alpha subtypes, and these were used individually to examine the subtype specificity of the neutralizing antibodies in the patients' sera. All three sera neutralized all the subtypes present in the 10 lymphoblastoid IFN fractions. These findings may explain why some patients who develop antibody-mediated resistance to treatment with rIFN-alpha 2 preparations are unable to respond again when treated instead with a human cell derived preparation containing many IFN-alpha subtypes.

Treatment of Carcinoid Syndrome with Recombinant Interferon Alpha-2a

The prognosis and the quality of life of patients with carcinoid tumors is related either to symptoms from the substances secreted or to progressive tumor growth. Medical treatment with cytotoxic agents is of marginal value for increasing life expectancy and reducing clinical symptoms. Recent studies with interferon have shown interesting results. In the present investigation, 22 patients with carcinoid tumors and syndrome were treated with recombinant interferon alpha-2a (r-IFN alpha-2a) at the dose of 6 x 10(6) IU intramuscularly daily for 8 weeks and three times weekly thereafter. The primary tumor was localized in the foregut (n = 11), midgut (n = 7), hindgut (n = 1), and unknown site (n = 3). Most cases had liver metastasis. Seventeen patients had elevated 5-hydroxyindoloacetic acid (5-HIAA) excretion and 5 had flushing and/or diarrhea as the only clinical manifestation. Six cases presented a complete syndrome (flushing, diarrhea and 5-HIAA excretion). Control of symptoms was obtained in 80% and a 5-HIAA level reduction in 58% of the patients. The interferon treatment was more effective for control of the carcinoid syndrome than for control of tumor growth. The treatment was well tolerated and fever, myalgia, anorexia and fatigue were the most frequent side-effects.

An escalating dose regime of recombinant interferon-alpha 2A in the treatment of chronic hepatitis C

Interferon-alpha (IFN-alpha) has proven useful in the treatment of chronic hepatitis C, but a relapse in response is frequently observed. The possible benefit of daily administration of recombinant IFN-alpha 2A at an escalating (from 1.5 to 9 MU) regime depending on the evolution of serum aminotransferase (ALT) levels was evaluated in 31 adult patients with chronic hepatitis C. At the end of the first month with 1.5 MU of rIFN-alpha 2A, 9/31 (29%) had normal ALT values. Then, 22 patients were given 3 MU daily and at the second month 4 patients (18%) normalized ALT values. The 18 non-responders received 6 MU and 4 of them (22%) normalized ALT values (1 patient dropped out). Finally, the remaining 13 non-responders were given 9 MU and in 4 (30%) ALT fell to normal ranges. Three non-responders to 1.5 MU normalized ALT values when the dose of rIFN-alpha 2A was increased (n = 2, 3 MU; n = 1, 9 MU). The overall response achieved was 68%. Within 3 months after cessation of treatment, 12/20 (60%) responder patients had a relapse in ALT levels. Therefore, although daily administration of rIFN-alpha 2A does not improve the results obtained with a thrice-weekly schedule, a proportion of non-responders could benefit from an escalating dose to a high amount (63 MU/week) of rIFN-alpha 2A.

Interferon-alpha therapy in atopic dermatitis.

Thirteen patients with a severe adult form of atopic dermatitis (AD) received 3.0 x 10(6) IU of recombinant interferon-alpha 2a (rIFN-alpha 2a) 3 times a week. A satisfactory response was obtained in 5 of them. Serum IgE levels in all 13 patients remained unchanged throughout the study. Flu-like symptoms were common, but clinical or laboratory adverse effects were otherwise slight. The moderately beneficial therapeutic effects observed in this study support a possible role for IFN-alpha in controlling immunologic deficiencies in atopic dermatitis.

Treatment of chronic hepatitis C by continuous subcutaneous infusion of interferon-alpha.

The effectiveness of a daily continuous infusion of interferon-alpha was evaluated in 12 patients (10 males, 2 females; mean age of 33 years, range 19-62) with biopsy-proven chronic active hepatitis C. Nine million units (MU) of recombinant interferon-alpha 2A (rIFN-alpha 2A) were administered by continuous subcutaneous infusion with a portable syringe pump, Graseby model MS 16A, for 24 h over 28 days. A significant decrease (P less than 0.01) in median serum alanine aminotransferase (ALT) levels was observed after the first week of treatment (96 IU/L, range 58-263) with respect to the pre-treatment values (188 IU/L, range 119-670). ALT became normal in four patients only by the fourth week. When IFN was interrupted, an increase in ALT was observed in all patients (1.5 to 5 times the pre-treatment values). The maximum decrease in ALT coincided with a significant increase in serum levels of the enzyme 2',5'-oligoadenylate (2-5A) synthetase (two to fourteen times the pretreatment values) and these parameters were inverse-correlated (r = -0.598, P less than 0.05). 2-5A synthetase levels returned to pre-treatment values after discontinuing IFN administration. Hepatitis C virus (HCV) RNA (as detected by the polymerase chain reaction using oligonucleotide primers of the NS5 region) was positive in all cases, remaining so during the treatment period. IgM antibody to HCV (as tested by ELISA) was present in 10/12 cases at baseline without changes throughout the study. No irreversible side effects were noted during therapy, which needed to modify the schedule.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid Function Abnormalities Associated with the Chronic Outpatient Administration of Recombinant Interleukin-2 and Recombinant Interferon-Alpha

We prospectively examined thyroid function during and following chronic, outpatient therapy with recombinant interleukin-2 (rIL-2) and Roferon-A (rIFN-alpha 2a). Twenty-two of 30 patients with advanced renal cell carcinoma treated on a phase II open pilot study of concomitant rIL-2 and rIFN-alpha 2a were included. Serum levels of thyroxine, triiodothyronine, free thyroxine index, thyrotropin, antithyroid antibodies, and thyrotropin (TSH) receptor binding antibodies were measured before therapy and after every other cycle. Selected patients underwent studies after every cycle and following completion of therapy. Twenty patients (91%) developed laboratory evidence of thyroid dysfunction, 11 (50%) developed hypothyroidism, five (23%) had a biphasic pattern, and four (18%) had hyperthyroidism. The incidence of thyroid dysfunction increased with increased number of treatment cycles. Transient hyperthyroidism was noted in six of the 11 patients studied after the first cycle and persisted after cycle three in only two patients. Hypothyroidism was not observed after cycle 1, but became increasingly frequent between cycles 2 (56%) and 6 (90%). Thyroid function normalized following therapy in nine of 12 patients tested. Antithyroid antibodies were identified pretherapy in five patients (23%) and de novo in none; TSH receptor binding antibodies were not detected. This study demonstrates a remarkably high frequency of reversible thyroid dysfunction in patients with advanced renal cell carcinoma treated with repeated cycles of rIL-2 plus rIFN-alpha 2a. We conclude that chronic therapy with rIL-2 and rIFN-alpha 2a produces thyroid dysfunction in virtually all patients most likely secondary to a nonspecific, nonautoimmune, toxic manifestation of prolonged treatment. IL-2 therapy may, therefore, produce thyroid dysfunction by more than one mechanism.

A pilot study of interferon alfa-2a in combination with fluorouracil plus high-dose leucovorin in metastatic gastrointestinal carcinoma.

Thirty-one assessable patients with metastatic adenocarcinoma of the gastrointestinal tract were entered onto a pilot study designed to assess the impact of recombinant interferon alpha-2a (rIFN alpha-2a) on the toxicity and pharmacokinetics of fluorouracil (5-FU) and leucovorin (LV). Patients received an initial cycle of 5-FU (370 or 425 mg/m2/d) with LV (500 mg/m2/d) for 5 days. If tolerated, the patient received the same dose of 5-FU/LV for the second cycle on days 2 to 6, with rIFN alpha-2a at 5 x 10(6) or 10 x 10(6) U/m2/d on days 1 to 7, or with 3 x 10(6) U/m2/d on days 1 to 14. In 26 matched cycles, rIFN alpha-2a administration was associated with an increased incidence of dose-limiting mucositis and diarrhea and a significantly lower median platelet nadir; rIFN alpha-2a did not significantly affect the median WBC or granulocyte nadir. Dose-limiting toxicity occurred in all six patients entered at 425 mg/m2/d of 5-FU/LV within two cycles. The majority of patients treated with 370 mg/m2/d of 5-FU/LV and 10 x 10(6) U/m2/d rIFN alpha-2a experienced grade 3 to 4 mucositis and diarrhea, whereas patients receiving 3 x 10(6) and 5 x 10(6) U/m2/d rIFN alpha-2a had acceptable toxicity. Administration of rIFN alpha-2a was associated with a dose-dependent decrease in 5-FU clearance. The increase in the area under the 5-FU concentration-time curve (AUC) was 1.3-fold and 1.5-fold in patients receiving 5 x 10(6) and 10 x 10(6) U/m2/d rIFN alpha-2a, respectively. Thus, the increase in 5-FU toxicity with rIFN alpha-2a may be explained by alterations in 5-FU pharmacokinetics. In 22 patients without prior 5-FU therapy, three complete (13.6%) and seven partial (31.8%) responses were seen, for an overall response rate of 45.4% (95% confidence interval, 24.4% to 67.8%). Since the 5 x 10(6) U/m2/d dose of rIFN alpha-2a increased the 5-FU drug exposure and was associated with acceptable toxicity, we recommend its further evaluation as given on days 1 to 7 in combination with 5-FU 370 mg/m2/d, with high-dose LV given on days 2 to 6.

Treatment of advanced malignant melanoma with recombinant interferon alfa‐2a in combination with DTIC: long‐term follow‐up of two phase II studies

The present studies were designed to examine whether treatment of disseminated melanoma with a combination of recombinant interferon alpha (rIFN alpha-2a) and DTIC may provide better results than either agent alone. Two dose levels of rIFN alpha-2a were examined with the same dose and schedule of DTIC administration. In the first study 76 patients were treated with rIFN alpha-2a (3 x 10(6) IU days 1-3, 9 x 10(6) IU days 4-70 then 9 x 10(6) IU TIW) plus DTIC (i.v. 200 mg/m2, escalating to 800 mg/m2 each 21 d) for 6 months or longer or until failure. Responses were seen in 26% of patients overall (7CR, 13PR) with the highest responses being seen in those assessed as having a good prognosis and in patients with skin and/or lung metastases. It was notable that males showed a better response than females and that patients with metastases in lymph nodes showed low responses. Response rates in 30 patients treated with high-dose rIFN alpha-2a (18 x 10(6) IU days 7-70) were not superior to that seen at the lower dose and was accompanied by significant increase in bone marrow toxicity. The duration of responses appeared longer than expected from responses to DTIC alone and four patients remain progression free at periods in excess of 3 years. Failure in nine of the responders was due to the development of brain metastases which emphasizes the need for additional treatment approaches to treat micrometastases at this site. The results of a randomized control study comparing DTIC alone with DTIC plus 'low' dose rIFN alpha-2a are awaited with interest.

Fluorouracil and recombinant interferon alfa‐2a in advanced gastrointestinal neoplasms

Based on preclinical studies which demonstrated synergy between recombinant interferon alfa-2a (rIFN alpha-2a) and 5-fluorouracil (5FU), clinical studies have been initiated to investigate this combination. The initial study conducted by investigators from the Albert Einstein Cancer Center reported a response rate of 76% with 13/17 patients with advanced colorectal carcinoma responding. To further evaluate this regimen, two clinical trials have been conducted in previously untreated advanced colorectal carcinoma patients with measurable disease. The regimen consisted of 5FU administered as a continuous infusion, 750 mg/m2/d for 5 consecutive days. Intravenous bolus administration of 5FU 750 mg/m2 was given weekly for 7 weeks starting 1 week after completion of the continuous infusion. rIFN alpha-2a, 9 MU, was administered subcutaneously three times weekly. In The University of Texas M.D. Anderson Cancer Center trial, 15/45 evaluable patients experienced partial response, and one patient achieved a complete response for an overall response rate of 35%. Another trial of this regimen conducted by Memorial Sloan-Kettering has reported a 26% response rate with 9/34 evaluable patients experiencing a partial response. Current randomized trials comparing this schedule of 5FU with rIFN alpha-2a to 5FU plus folinic acid or single-agent 5FU may clarify its role in the treatment of advanced colorectal carcinomas.

Studies of interferons in the therapy of melanoma.

Melanoma does not respond meaningfully to systemic chemotherapy. No significant improvement in overall survival has been observed with any therapy in the setting of advanced disease, nor in the adjuvant setting. The most active single drugs achieve 14% to 22% response rates in larger phase II series, and drug combinations have not in general improved true response rates by 15% or more. Experience with recombinant interferon alpha-2 (rIFN alpha 2) administered by a variety of schedules and routes has demonstrated tumor response rates of 12% to 22% in advanced melanoma. Administered combined with chemotherapy, rIFN alpha 2 has improved response rates in some, but not all trials to date. On the basis of increased responsiveness noted to be inversely related to tumor size, IFN alpha has been explored over the past 7 years as an adjuvant to definitive surgery for melanoma. The North Central Cancer Treatment Group (NCCTG) and Eastern Cooperative Oncology Group (ECOG) have recently completed trials of 3 and 12 months' duration of maximal dosages of rIFN alpha 2 in subjects with high-risk resected deep primary or lymph node metastatic melanoma. These randomized controlled studies completed accrual in 1990. The ECOG trial EST 1684 has tested the effect of rIFN alpha 2b, given intravenously daily for 5 days per week for 4 weeks at 20 x 10(6) IU/m2/d, then subcutaneously three times a week at 10 x 10(6) IU/m2/d for 11 months. A series of three analyses is planned for the ECOG trial, and the first of these interim analyses was reported to the ECOG in June, 1990, revealing an encouraging divergence of survival curves that does not achieve statistical significance at this early time. A randomized controlled study of 3 months' duration of rIFN alpha 2a at 12 x 10(6) IU/m2/d intramuscularly three times a week performed by the NCCTG is also in too early a stage to allow definitive conclusions yet. The toxicity of IFN alpha administered at maximum tolerated doses has been significant in terms of constitutional symptoms and organ dysfunction. There have been two instances of fatal toxicity observed in the ECOG study (286 subjects). Consideration of lower, more tolerable dosage regimens has been derived from the desire to evaluate longer periods of IFN alpha 2 therapy, and long-term maintenance treatment with IFN alpha 2 in adjuvant melanoma therapy. In addition, immunologic studies suggest that dosages of 3 x 10(6) IU/m2/d may be more immunologically active in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)

Interaction Between 5-FluorouraciI, [6RS]Leucovorin, and Recombinant Human Interferon-α2a in Cultured Colon Adenocarcinoma Cells

Recombinant human interferon-alpha 2a (rIFN-alpha 2a; 500 or 5,000 IU/mL) or [6RS] leucovorin ([6RS]LV; 1 microM) each potentiated the cytotoxic activity of 5-fluorouracil (FUra) by 2.6- to 3.2-fold during 72 hr exposures in two human colon adenocarcinoma cell lines (GC3/c1; VRC5/c1). When all three agents were combined, FUra cytotoxicity was further potentiated by 3.2- to 4.3-fold (total 10- to 14-fold). Potentiation of FUra cytotoxicity occurred at clinically achieveable concentrations of rIFN-alpha 2a and [6RS]LV. Effects were reversed by dThd (20 microM), although the activity of CB3717, a quinazoline-based, specific inhibitor of thymidylate synthase, was not potentiated by rIFN-alpha 2a. Data suggest the requirement of a 5-fluoropyrimidine for biochemical modulation and interaction at the level of thymidylate synthase or DNA.