HK1018595B - Use of consensus interferon for reducing the side effects of interferon treatment in viral hepatitis - Google Patents

Description

The present invention relates to the use of a consensus human leukocyte interferon for the manufacture of a medicament for the treatment of diseases.

Background of the Invention

Interferons are a subclass of cytokines that exhibit both antiviral and antiproliferative activity. On the basis of biochemical and immunological properties, human interferons are grouped into three classes: interferon-alpha (leukocyte), interferon-beta (fibroblast) and interferon-gamma (immune). At least fourteen alpha interferons (grouped into subtypes A through H) having distinct amino acid sequences have been identified by isolating and sequencing DNA encoding these polypeptides. Alpha interferons have received considerable attention as potential therapeutic agents due to their antiviral and antitumor growth inhibition.

The purification of interferon from human leukocytes isolated from the buffy coat fraction of whole blood is described in U.S. Patent No. 4,503,035. Human leukocyte interferon prepared in this manner contains a mixture of different human leukocyte interferon amino acid sequences. The purified material has a specific activity of from 0.9 x 10⁸-4 x 10⁸ units/mg. of protein when assayed on the MDBK bovine cell line and from 2 x 10⁶-7.6 x 10⁸ units/mg. of protein when assayed on the Ag 1732 human cell line. The cytopathic effect inhibition assay used to determine interferon anti-viral activity is disclosed in U.S. Patent No. 4,241,174. The measured interferon activity was calibrated against a reference standard for human leukocyte interferon provided by the National Institutes of Health.

The construction of recombinant DNA plasmids containing sequences encoding at least part of human leukocyte interferon and the expression in E. coli of a polypeptide having immunological or biological activity of human leukocyte interferon is disclosed in U.S. Patent No. 4,530,901.

The construction of hybrid alpha-interferon genes containing combinations of different subtype sequences (e.g., A and D, A and B, and A and F) is disclosed in U.S. Patent Nos. 4,414,150, 4,456,748, and 4,678,751.

U.S. Patents Nos. 4,695,623 and 4,897,471 disclose novel human leukocyte interferon polypeptides having amino acid sequences which include common or predominant amino acids found at each position among naturally-occurring alpha interferon subtype polypeptides and are referred to as consensus human leukocyte interferon (IFN-con). The IFN-con amino acid sequences disclosed are designated IFN-con₁, IFN-con₂, and IFN-con₃. The preparation of manufactured genes encoding IFN-con and the expression of said genes in E. coli are also disclosed.

A purification of IFN-con₁ produced in E. coli is described in Klein et al. (J. Chromatog. 454, 205-215 (1988)). IFN-con₁ purified in this manner is reported to have a specific activity of 3 x 10⁹ units/mg. protein as measured in the cytopathic effect inhibition assay using the T98G human cell line (Fish et al. J. Interferon Res. 9, 97-114 (1989)). Purified IFN-con₁ comprises three isoforms as determined by isoelectric focusing which have been identified as methionyl IFN-con₁, des-methionyl IFN-con₁ and des-methionyl IFN-con₁ with its N-terminus blocked by an acetyl group. (Klein et al. Arch. Biochem. Biophys. 276, 531-537 (1990)).

Alpha-interferon is currently approved in the United States and other countries for the treatment of hairy cell leukemia, venereal warts, Kaposi's Sarcoma (a cancer commonly afflicting patients suffering from Acquired Immune Deficiency Syndrome (AIDS)), and chronic non-A, non-B hepatitis. Two variants of alpha interferon have received approval for therapeutic use: Interferon alfa-2a, marketed under the trade name Roferon®-A, and Interferon alfa-2b, marketed under the trade name INTRON® A. The amino acid sequences of Roferon®-A and INTRON® A differ at a single position but otherwise are identical to the amino acid sequence of alpha-interferon subtype 2 (subtype A).

In addition to the labeled indications, alpha-interferon is being used or evaluated alone or in conjunction with chemotherapeutic agents in a variety of other cellular proliferation disorders, including chronic myelogenous leukemia, multiple myeloma, superficial bladder cancer, skin cancers (basal cell carcinoma and malignant melanoma), renal cell carcinoma, ovarian cancer, low grade lymphocytic and cutaneous T cell lymphoma, and glioma. Alpha-interferon may be effective in combination with other chemotherapy agents for the treatment of solid tumors that arise from lung, colorectal and breast cancer (see Rosenberg et al. "Principles and Applications of Biologic Therapy" in Cancer: Principles and Practices of Oncology, 3rd ed., Devita et al., eds. pp. 301-547 (1989), Balmer DICP, Ann Pharmacother 24. 761-768 (1990)).

Alpha-interferons are known to affect a variety of cellular functions, including DNA replication and RNA and protein synthesis, in both normal and abnormal cells. Thus, cytotoxic effects of interferon are not restricted to tumor or virus infected cells but are also manifested in normal, healthy cells as well. As a result, undesirable side effects arise during interferon therapy, particularly when high doses are required. Administration of interferon can lead to myelosuppression resulting in reduced red blood cell, white blood cell and platelet levels. Higher doses of interferon commonly give rise to flu-like symptoms (e.g., fever, fatigue, headaches and chills), gastrointestinal disorders (e.g., anorexia, nausea and diarrhea), dizziness and coughing. It would be useful to reduce or eliminate the undesirable side effects of interferon therapy without diminishing the therapeutic benefits of such therapy.

Therefore, an object of this invention is to provide therapeutic agents for the treatment of conditions that are susceptible of treatment with an interferon, wherein the undesirable side effects normally associated with alpha interferon treatment are significantly diminished compared to currently practiced treatment regimens or eliminated entirely. Another object of the invention is to achieve enhanced therapeutic benefit in the treatment of diseases with interferon as compared to currently practiced regimens, with substantially no corresponding increase in the frequency or severity of undesirable side effects.

Summary of the Invention

The invention encompasses methods the use of a consensus human leukocyte interferon for the manufacture of a medicament for the treatment of various conditions susceptible of treatment with an interferon, involving administering to a mammal, preferable a human, a therapeutically effective amount of consensus 'human leukocyte interferon (IFN-con). The invention is based on the discovery that IFN-con does not cause the same degree of side effects in patients as do alpha interferons. The conditions that may be treated are generally those that are susceptible to treatment by alpha interferons. In other words, IFN-con is useful to treat substantially the same conditions that may be treated with alpha interferons, such as Intron® A.

Viral conditions treatable by IFN-con are hepatitis A, hepatitis C, hepatitis B, and hepatitis Delta.

Although it has previously been appreciated that the above conditions can be treated with alpha interferon, side effects accompanying such treatment have severely limited the overall usefulness of such treatment. In some cases, side effects accompanying alpha interferon treatment have virtually ruled out treatment using alpha interferon. Thus, for purposes of the present invention, conditions that can be treated with IFN-con include those conditions in which alpha interferon treatment shows some efficacy, but which may not be treatable with known interferons because the negative side effects outweigh the benefits of the treatment. It has now been discovered and disclosed herein that treatment with a non-naturally occurring interferon, selected from consensus human leukocyte interferons (IFN-con) results in substantially reduced or eliminated side effects as compared to treatment with alpha interferon. The reduction or elimination of side effects is expected to be demonstrated regardless of the condition being treated. The reduction or elimination of side effects discovered for IFN-con could not have been predicted based on the results reported in the prior art. The actual clinical results presented herein clearly demonstrate not only that IFN-con causes reduced or non-existent side effects at the same dose level as alpha interferon, but that 3 to 5 times more IFN-con may be administered without causing dose-limiting side effects.

Additionally, it is shown below that IFN-con has similar or higher activity than INTRON® A in the above described indications. The administration of a therapeutically effective amount of IFN-con results in more rapid or more extensive treatment of a cellular proliferative disorder compared to currently practiced methods, wherein no corresponding increase in the frequency or severity of associated undesirable side effects occurs. In addition, a therapeutically effective amount of IFN-con may be less than the amount of an interferon used in currently practiced regimens. As a result, in some cases, a decreased dose of IFN-con gives the same therapeutic benefit as higher doses of other interferons but with a decrease or elimination of undesirable side effects associated with currently practiced interferon therapy.

IFN-con is a nonnaturally-occurring polypeptide having antiproliferative activity. Preferably, IFN-con is a polypeptide having the amino acid sequence of IFN-con₁, IFN-con₂, or IFN-con₃. Most preferably, IFN-con has the amino acid sequence of IFN-con₁.

Detailed Description of the Invention

As employed herein, consensus human leukocyte interferon (IFN-con) means a nonnaturally-occurring polypeptide, which predominantly includes those amino acid residues that are common to all naturally-occurring human leukocyte interferon subtype sequences and which includes, at one or more of those positions where there is no amino acid common to all subtypes, an amino acid which predominantly occurs at that position and in no event includes any amino acid residue which is not extant in that position in at least one naturally-occurring subtype. IFN-con encompasses but is not limited to the amino acid sequences designated IFN-con₁, IFN-con₂ and IFN-con₃ which are disclosed in commonly owned U.S. Patents 4,695,623 and 4,897,471, the entire disclosures of which are hereby incorporated by reference. DNA sequences encoding IFN-con may be synthesized as described in the above-mentioned patents or other standard methods.

IFN-con polypeptides are preferably the products of expression of manufactured DNA sequences transformed or transfected into bacterial hosts, especially E. coli. That is, IFN-con is recombinant IFN-con. IFN-con is preferably produced in E. coli is purified by procedures known to those skilled in the art and generally described in Klein et al., supra (1988) for IFN-con₁. Purified IFN-con may comprise a mixture of isoforms, e.g., purified IFN-con₁ comprises a mixture of methionyl IFN-con₁, des-methionyl IFN-con₁ and des-methionyl IFN-con₁ with a blocked N-terminus (Klein et al., supra (1990)). Alternatively, IFN-con may comprise a specific, isolated isoform. Isoforms of IFN-con are separated from each other by techniques such as isoelectric focusing which are known to those skilled in the art.

The subject invention provides a medicament for treating a condition treatable by alpha interferon while reducing or eliminating one or more side effects typically associated with alpha interferon treatment, involving administering a therapeutically effective amount of IFN-con to a patient. A preferred embodiment involves a therapeutically effective amount of IFN-con₁, IFN-con₂, or IFN-con₃. Most preferably, a therapeutically effective amount of IFN-con₁ is administered.

The phrase "reducing or eliminating one or more side effects associated with interferon administration" is believed to be clear and understandable to those of ordinary skill in the relevant art. Generally, one may use any of a variety of measures of number and degree of severity of side effects associated with interferon therapy to determine whether the side effect profile is different from one interferon to another. One suitable interferon for comparative purposes with consensus interferon is Intron® A, interferon alfa-2b, sold by Schering-Plough.

A convenient way of rating severity of side effects is to use a standard scale such as that accepted by the WHO (World Health Organization). The scale, which is currently widely used by clinicians, utilizes grade levels of side effects as follows: grade I, mild; grade II, moderate; grade III, severe; grade IV, life threatening. Although there is some subjectivity involved in these ratings, if the same clinician is rating groups of patients, a comparison of side effect profiles between two drugs may be valid and acceptable to doctors. To make a comparison, doctors will frequently look at whether administering a given drug at a given dose level results in a dose-limiting toxicity (DLT). A DLT occurs when a patient judges a side effect as intolerable. When this occurs, a doctor may either reduce the dose (typically by 3 million units in the case of Intron® A or consensus interferon) or take the patient off of the drug for a period of time followed by resuming administration at the same or a lower dose. In any case, when a DLT is encountered, the result can be a sub-optimal treatment regime with less than optimal efficacy. Thus, another way of expressing a reduction in side effects is to refer to a reduced number of DLT's at a given dose level. A comparison of DLT's is presented for Intron® A and consensus interferon in Example 3. Although other measures of side effect profiles may be employed, the result is the same: as compared to other interferons, especially alpha interferons such as Intron® A and Roferon® (Hoffmann La Roche), consensus interferon results in fewer DLT's and, generally, a patient that feels better at all dose levels that are useful to treat diseases.

Other conditions suitable for treatment with IFN-con include a variety of viral diseases. These diseases are hepatitis A, hepatitis B, hepatitis C, and hepatitis Delta.

IFN-con may be used alone or in combination with other therapeutics for the treatment of the indications described herein. For example, IFN-con may be administered in conjunction with a therapeutically effective amount of one or more chemotherapy agents such as busulfan, 5-fluoro-uracil (5-FU), zidovudine (AZT), leucovorin, melphalan, prednisone, cyclophosphamide, dacarbazine, cisplatin, and dipyridamole. IFN-con may also be given in conjunction with cytokines such as interleukin-2 (IL-2).

A therapeutically effective amount of IFN-con may be administered in combination with a therapeutically effective amount of one or more factors that stimulate myeloid differentiation so as to overcome the effects of myelosuppression observed during interferon treatments. Such agents include, but are not limited to, G-CSF, GM-CSF, IL-1, IL-3, IL-6, erythropoietin and SCF. Stem cell factor (SCF) stimulates the proliferation of early hematopoietic progenitor cells and has been described in U.S. Serial No. 573, 616, the disclosure of which is hereby incorporated by reference. A preferred agent is G-CSF.

The Example shows data obtained from clinical trials involving patients infected with hepatitis

Also disclosed for are pharmaceutical compositions comprising a therapeutically effective amount of IFN-con together with pharmaceutically acceptable carriers, adjuvants, diluents, preservatives and/or solubilizers. Pharmaceutical compositions of IFN-con include diluents of various buffers (e.g., Tris-HCl, acetate, phosphate) having a range of pH and ionic strength, carriers (e.g., human serum albumin), solubilizers (e.g., tween, polysorbate), and preservatives (e.g., thimerosol, benzyl alcohol). In general, components of pharmaceutical compositions can be selected from among those commonly employed with interferons and other antiproliferative or antiviral agents and which are known to those skilled in the art. A pharmaceutical composition of IFN-con is supplied as an injectable solution or as a lyophilized powder which is reconstituted in an appropriate diluent prior to injection.

A therapeutically effective amount of IFN-con can be determined by one skilled in the art taking into account such variables as the half-life of IFN-con preparations, route of administration and the condition being tested. In general, a therapeutically effective amount of IFN-con for the treatment of a cell proliferation disorder will be in the range of 2 x 106 to 60 x 106 units per patient administered several times per week. Doses in the lower part of the range are effective in the treatment of hairy cell leukemia while doses in the higher part of the range are suitable for the treatment of Kaposi's Sarcoma. Therapeutically effective amounts of IFN-con will preferably result in tumor remission of 20-80% depending upon the specific tumor type for a period of at least six months. In general, a therapeutically effective amount of IFN-con for the treatment of a viral condition will be in the range of 3 x 106 to 30 x 10⁶ units, preferably 6 x 106 to 15 x 106 units, per patient, administered several times (e.g., 2-7, preferably 3) per week.

The route of administration will preferably be by injection into the blood of a mammal where the injection may be intravenous, intramuscular, subcutaneous or intralesional. Administration may also be by oral or nasal routes. The suitability of a given pharmaceutical composition for a given route of administration will be apparent to one skilled in the art.

The following example is offered to more fully illustrate the invention but are not to be construed as limiting the scope thereof.

EXAMPLE

IFN-con₁ was produced in E. coli using methods described in U.S. Patent Nos. 4,695,623 and 4,897,471. IFN-con₁ was purified by procedures generally described in Klein et al., supra (1988). For subcutaneous administration in the current study, IFN-con₁ was supplied as a sterile protein solution in sodium phosphate buffer. If required, dilution was made into sterile saline.

Zidovudine (AZT) was purchased from Burroughs-Wellcome Co. and used as directed on the package insert.

Intron® A was purchased from Schering Corp. as a sterile, lyophilized formulation which was resuspended in diluent as directed on the package insert.

r-metGCSF was produced in E. coli using methods generally described in U.S. Patent No. 4,810,643, the disclosure of which is herein incorporated by reference. r-metGCSF was prepared as a sterile protein solution in 10 mM sodium acetate, 5% mannitol and 0.004% Tween 80 at pH 4.0 at a concentration of 0.3 mg/ml. If required, dilution was made into sterile 5% glucose in water (D₅W).

Safety, Tolerance and Efficacy of IFN-con ₁, Administered to Patients having Hepatitis C (HCV)

Improved Dose Tolerability. Treatment with type-one interferons causes several side effects which can limit the absolute doses patients can be given for treatment for a specific disease. These side effects include: flu-like symptoms, diarrhea, myelosuppression, elevated liver function tests, and mental status changes. These toxicities are rated according to the WHO (World Health Organization) scale as; grade I (mild), grade II (moderate), grade III (severe) and grade IV (life threatening). Toxicities from type one interferon treatment can range from grade I to grade IV. Any toxicity during type one interferon treatment judged to be non-tolerable by the patient or physician will result in a dose reduction or dose schedule modification. These dose modifications can lead to sub-optimal treatment regimes which result in less than optimal efficacy. Consensus interferon allows for optimal dosing to be achieved and maintained over the course of treatment without accompanying dose limiting toxicity of any grade.

A clinical trial using consensus interferon to treat chronic Hepatitis C infection was initiated to study the effects of several doses of the drug. Patient data from consensus interferon treated patients were compared to data from patients with similar disease and demographic characteristics, treated with either Interferon-alpha 2a (Roferon®) or Interferon-alpha 2b (Intron®A) by the same principal investigator.

Study Design. The study included at least 30 patients infected with HCV exhibiting elevated (at least 1.5 times the upper limit of normal) alanine transferese (ALT: a liver enzyme) levels; the upper limit of normal in this study is 35 milliunits per milliliter (35 mu/mL). Additionally, efficacy of IFN-con₁ was evaluated by measuring antiviral activity via PCR analysis and by measuring ALT values during the course of treatment. Finally, historical data from HCV clinical studies of other recombinant interferons-alpha, specifically recombinant interferon-alpha-2a (Roferon®) and alpha-2b (Intron® A) was compared with data resulting from this study with respect to safety and changes in ALT values.

Eligible patients were enrolled into one of the IFN-con₁ dose cohorts summarized in Table 1. Table 3

	Doses/7-day Week*	No. Patients
3	3	5
6	3	5
9	3	5
12	3	5
15	3	5

Table 3

* Doses separated by at least 48 hours

Dose cohorts were enrolled sequentially with two-week intervals between the cohorts. Specifically, five patients were entered into the first cohort and were evaluated for a two week safety period if no Grade III or higher toxicity attributable to IFN-con₁ was observed, five patients were entered into the next cohort (6 MU). However, if any patient was observed to have Grade III or higher toxicity attributable to IFN-con₁, three additional patients were entered into the first cohort and were evaluated for two weeks. If no additional Grade III or higher toxicity attributable to IFN-con₁ was observed, patients were then entered into the next cohort (6 MU), but if any additional Grade III or higher toxicity attributable to IFN-con₁ was observed, patients were not entered into the next-higher dose cohort (6 MU). Escalation to the 9, 12, 15, 18, and 24 MU cohorts proceeded according to the same rules outlined above. In addition, if two or more patients experienced Grade III or higher toxicity attributable to IFN-con₁ at any dose level, no additional patients were enrolled in that cohort, and patients already on study treatment in that cohort or at a higher dose level were dose reduced to the dose level below that at which two or more Grade III or higher toxicities occurred. However, additional patients may continue to be enrolled (up to a total of 10 additional) at the dose level below that at which two or more Grade III or higher toxicities occurred.

If a patient in any of the cohorts experienced a Grade III toxicity attributable to IFN-con₁ during or after the two-week initial evaluation, IFN-con₁ was withheld until the toxicity diminished to Grade II or less. Treatment was then resumed at the next-lower dose-level. If the patient was receiving the 3 MU dose at the time of the Grade III toxicity, treatment was resumed at 2 MU. If any patient experienced a Grade IV toxicity attributable to IFN-con₁, the patient was withdrawn from study. Patients were allowed to undergo three dose reductions during the course of study treatment (but not dosed-reduced below a dose level of 2 MU). Any patient requiring a fourth dose reduction for toxicity would be withdrawn from study treatment. Fever and chills lasting less than 24 hours, fatigue, headache, or Grade II or less toxicity were not considered dose-limiting toxicities unless they were determined to be intolerable to the individual patient. The drug was home-administered by either the patient or a third party (after successful completion of training).

Patients were evaluated at three months for response based on ALT level changes.

Results:

Patients were entered and enrolled into the cohorts described above. No dose limiting toxicities were observed in any patients during the first two weeks for the 3, 6, 9 and 12 MU dose groups respectively. One dose limiting toxicity was observed in one patient receiving 15 MU within the first two weeks of dosing.

The observed toxicity was Grade II intolerable "flu-like" symptoms. The patient was dose reduced to 12 MU.

Dose limiting toxicities for the 12 week treatment period for each of the cohorts and the historical IFN-alpha 2 patients were as follows: Table 2

	Dose of IFN-con1 (Million Units)	Per Cent DLTs	Toxicity
n=4	3	0	-
n=5	6	0	-
n=5	9	0	-
n=5	12	20%	"Flu-like"
n=5	15	20%	"Flu-like"
n=19	3 MU IFN-alpha 2	32%	"Flu-like"

As illustrated by the above table, patients receiving IFN-con1 at doses between 3 and 15 MU three times weekly experienced fewer dose limiting toxicities than patients receiving IFN-alpha 2. Since IFN-alpha 2 is only approved up to 3 MU for this indication, it was not possible to make a clinical comparison at higher dose levels of IFN-alpha 2. However, it is expected that the number of DLT's would be substantially higher for IFN-alpha 2 at higher dose levels. Table 3

Response after 12 weeks of treatment
	Dose of IFN-con1(Million Units)	Response Rate *
n=4	3	25%
n=5	6	60%
n=5	9	80%
n=5	12	60%
n=4	15	75%
n=19	3 MU IFN-alpha 2	47%

Table 3

* Complete plus partial responses

As illustrated by the above table, patients receiving IFN-con₁ at doses between 3 and 15 MU three times weekly had ALT response rates that were at least as good as those observed with 3 MU of IFN-alpha 2.

The above demonstrates that treatment with IFN-con₁ results in a favorable efficacy rate with greater drug tolerability compared to treatment with IFN-alpha 2.

Claims (10)

1. The use of a consensus human leukocyte interferon for the manufacture of a medicament for treating a patient having a condition treatable by an interferon while reducing or eliminating one or more side effects associated with interferon administration,    wherein the condition is hepatitis A, hepatitis B, hepatitis C or hepatitis Delta.
2. A use according to Claim 1, wherein the side effect is selected from headache, fever, chills, nausea, anorexia, depression, and insomnia.
3. A use according to Claim 1, wherein the consensus human leukocyte interferon is selected from IFN-con₁, IFN-con₂, and IFN-con₃.
4. A use according to Claim 3, wherein the consensus human leukocyte interferon is IFN-con₁.
5. A use according to Claim 1 wherein the consensus human leukocyte interferon is a product of procaryotic expression of an exogenous DNA sequence.
6. A use according to Claim 1, wherein the medicament is for administration orally, intravenously, intramuscularly, subcutaneously, intranasally, or intralesionally.
7. A use according to Claim 1, wherein the medicament contains from 2 x 10⁶ to 30 x 10⁶ units per patient.
8. A use according to Claim 1, wherein the medicament contains from 6 x 10⁶ to 15 x 10⁶ units per patient.
9. A use according to Claim 1, wherein the patient is a human.
10. A use according to Claim 1, wherein the medicament also contains a therapeutically effective amount of G-CSF.