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Absence of Neutralizing Antibodies to Interferon in Condyloma Acuminata and Cancer Patients Treated with Natural Human Leukocyte Interferon Mei-June Liao, Helena R. Axelrod, Martha Kuchler, Yum-Keung Yip, Elisabeth Kirkbright, and Douglas Testa

Interferon Sciences, New Brunswick. New Jersey

Human interferons (IFNs) have been used in the clinic for over a decade; their therapeutic efficacy has been established for human cancers [I] and viral diseases [2]. Four ofthe most commonly used IPNs are recombinant IFN-a2a, recombinant IPN-a2b, cell-line derived lymphoblastoid lPN-an 1, and leukocyte-derived IFN-an3. In recent years, it has been documented that patients treated with recombinant IPN-a2a [3], IPN-a2b [4], and lymphoblastoid interferon (lPN-an 1) [5] have developed neutralizing antibodies to IPN. A similar antibody response was found in patients treated with human IPN-I3; however, recombinant human IFN-')' appears to be an exception [6]. The level of antibody to lPN-a in the patient's serum after therapy may be directly associated with the quantity of IPN delivered during treatment, the mode of administration of the drug, the disease [7] and the population being treated [3], and possibly the inherent nature ofthe drug itself [8]. In addition, the level of antibody detected in the sera of these patients also appears to depend on the assay used. The presence of neutralizing anti-IFN antibodies has the potential of blocking the therapeutic effects ofIPN and therefore may be a significant factor in the course of clinical treatment. Although some investigators have not found a direct correlation between disease progression and the presence or absence ofthe anti-IFN antibody, clinical data have accumu-

Received 13 June 1991; revised 17 November 1991. Presented in part: annual meeting of the International Society for Interferon Research. November 1988. Kyoto. Japan. Written informed consent was obtained from all participants. Current addresses: CYTOGEN. Princeton, NJ (H.R.A.); Public Health Research Institute, New York (Y.-K.Y.); R. W. Johnson Pharmaceutical Research Institute. Raritan. NJ (E.K.). Reprints or correspondence: Dr. Douglas Testa. Interferon Sciences, 783 Jersey Ave., New Brunswick. NJ 08901. The Journal of Infectious Diseases 1992;165:757-60 © J 992 by The University of Chicago. All rights reserved. 0022-\899/92/6504-0027$0 \.00

lated in which patients who have developed antibodies to lPN-a therapy develop a concomitant loss oflFN-a efficacy [9]. The loss of clinical response may not only be due to the absolute presence of anti-IFN antibodies but also to the quantity and effects (e.g., binding, neutralizing, or both) of these antibodies. Some patients who have become resistant to the therapeutic benefits of recombinant forms of IFN-a have responded effectively when treated with an alternative source of IFN (e.g., human leukocyte-derived IFN-a [10, 11]. In fact, natural human leukocyte IFN has been used therapeutically over extended periods of time for the treatment of osteogenic sarcoma, juvenile laryngeal papillomatosis, and chronic viral hepatitis, with no detection ofneutralizing antibodies. We used a highly purified form of natural human leukocyte-derived IFN-a (an3) containing multiple subspecies, for the treatment of condylomata acuminata and cancer. Matched patient sera, after repeated courses of IPN-an3 injection, were evaluated for the presence of antibodies to human IFN-a. We tested for anti-IFN-a antibodies in patients using three different sensitive assays.

Materials and Methods Patients and Serum Samples

Serum samples from four groups were evaluated: (1) 32 untreated normal healthy persons, (2) 11 cancer patients from a phase I clinical study who were receiving escalating doses of IFN-an3 (Alferon N Injection; Interferon Sciences, New Brunswick, NJ), (3) 128 condyloma acuminata patients treated with IFN-an3, and (4) 39 condyloma acuminata patients treated with a placebo preparation matched to the preparation of IFN-an3. The cancer patients with advanced malignant disease of solid tumor origin received five intramuscular injections per week of 3, 6, or 9 X 106 IU of IFN-an3 for 2 weeks. The condyloma

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Human leukocyte-derived interferon-a (IFN-an3) was used to treat condyloma acuminata patients in a double-blind placebo-eontrolled clinical study. The incidence of antibody formation to IFN-a was evaluated in matched patient sera from the control placebo and the IFN-an3 treatment groups. Sera from IFN-an3-treated phase I cancer patients and untreated healthy donors were also evaluated. Three sensitive assay methods (ELISA, competitive immunoradiometric, and antiviral neutralization) were used in these evaluations. The overall levels of detectable binding anti-IFN-a antibodies in the patients were similar to those of the normal donors. No neutralizing antibodies were generated in the patients after repeated treatment with natural IFN-an3.

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Concise Communications

IFN-an3 Preparation Human leukocyte IFN (IFN-an3) was produced from normal healthy human donor leukocytes induced by Sendai virus. The crude interferon was purified by immunoaffinity chromatography using the murine NK2 monoclonal antibody (Celltech, Slough, VK). The final purified IFN preparation had an antiviral specific activity of --2.0 X 108 IV/mg compared with the National Institutes of Health leukocyte reference preparation (Ga-23-902-530) and a purity of~95%. The antiviral cytopathic effect assay used to determine IFN activity has been reported [12]; it quantitates the ability of a sample to protect a human epidermoid cell monolayer (HEp-2) from lysis by vesicular stomatitis virus.

Assays for Antibodies to Human IFNs Competitive immunoradiometric (IRMA). This solid-phase IRMA IFN-binding assay (Cell tech) was reformatted as an 25 ng/ml in the ELISA, >50%BI in the cIRMA, or both. When these serum samples were tested by neutralization assay, no neutralizing antibody was found. In addition, the data from all clinical patients studied show no evidence of neutralizing antibody development to natural leukocyte IFN (IFN-an3). Data from the present and previous studies suggest that differences do exist between preparations of natural and recombinant forms ofIFN-a. Some differences might be attributed to the presence of posttranslational modifications on the cell line- and leukocyte-derived forms ofIFN-a [14, IS] and the multisubtype composition of naturally derived IFNa. However, patients with certain diseases have an inherently higher frequency of antibody development during IFN-a therapy, which appears to be controlled by the doses and the duration of treatment [3, 7]. At this time, it is still unclear whether the development of circulating antibodies to IFN-a during IFN-a therapy is cause for concern in those patients who continue to respond to treatment. However, it is becoming clear that in those losing responsiveness to recombinant forms of IFN-a therapy, replacement with the natural form of IFN-a is beneficial.

1ID 1992;165 (April)

Absence of neutralizing antibodies to interferon in condyloma acuminata and cancer patients treated with natural human leukocyte interferon.

Human leukocyte-derived interferon-alpha (IFN-alpha n3) was used to treat condyloma acuminata patients in a double-blind placebo-controlled clinical s...
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