Clinical studies with ampligen (mismatched double-stranded RNA).

Results of an ongoing clinical study of a mismatched double-stranded (ds) RNA, termed Ampligen, in patients with metastatic cancer are described. In a pilot study of Ampligen (lot 1) involving mostly hematologic malignancies, patients received cumulative doses up to approximately 450 mg without untoward effects. Evidence of biologic/antitumor effects was observed (3/5 patients) by monitoring tumor-specific markers or tumor cell morphology. In patients with solid tumors receiving lot 2, Ampligen cumulative doses over 4 g were well tolerated. The drug was given by intravenous infusion (10-80 mg/infusion, twice weekly), in some instances for more than 1 year, without clinically significant side effects. Specifically, no evidence of hematologic, liver, or renal toxicity, which was previously noted with other dsRNAs, was observed. Side effects consisted of occasional mild fatigue or flu-like symptoms. Fever, when encountered, was transient and low grade (less than 100.5 degrees F). Importantly, an analysis of patient sera for dsRNA antibodies revealed that no patient had evidence of specific antibodies directed against Ampligen. Other dsRNAs cause up to a 60% incidence of antibody formation. Additionally, a novel method was developed to monitor Ampligen blood levels. In a survey of seven patients, Ampligen had a mean plasma half-life of 23 min. Ampligen administration can also result in activation of both natural killer (NK) cells and a lymphocyte, interferon-associated, intracellular enzyme. Dose-dependent antitumor effects were seen in several solid tumors; in doses of 10-40 mg, 3/9 patients showed stable disease for up to 1 year. At the 80-mg dose level, 2/5 patients showed tumor regressions (mixed and partial responses).(ABSTRACT TRUNCATED AT 250 WORDS)

Immunomodulating effects of synthetic polyribonucleotides.

The polynucleotide complexes are a class of compounds whose activities to date deserve close scrutiny with respect to their potential role as biological response-modifying agents in human disease. The challenge for the future lies in directing and controlling their activity with respect to a single desired effect, such that intelligent interference in patients with immunological aberrancies might occur.

Preclinical studies with Ampligen (mismatched double-stranded RNA).

Historically, double-stranded (ds) RNAs have been largely over-looked as potentially valuable anticancer/antiviral drugs, primarily because of the many clinical toxicities and lack of efficacy associated with the first clinically tested dsRNA--polyinosinic-polycytidylic acid (rIn X rCn). However, studies summarized herein demonstrate that the therapeutic ratio of dsRNAs can be greatly enhanced by purposeful mispairing of bases. For example, a mispaired dsRNA, termed Ampligen (rIn X r(C12,U)n), shows strong antitumor activity in a variety of relevant test systems with little or none of the toxicities associated with rIn X rCn. Furthermore, Ampligen demonstrates a much wider therapeutic spectrum than that displayed to date by any single type of interferon (natural or recombinant DNA-derived). Importantly, Ampligen, the product of a straight-forward enzymatic synthesis, shows excellent lot-to-lot biological and biophysical specifications, which is often not the case with biologically derived new compounds. Furthermore, a significant fraction of human solid tumors, which are largely unresponsive to conventional chemotherapy or interferon (IFN), is sensitive to Ampligen in a fresh human tumor clonogenic assay. Indeed, whereas 50% of untreated and IFN-treated athymic mice engrafted with human renal cancer cells die within 20-22 weeks, mice treated with Ampligen survive a minimum of 32 weeks (p less than 0.0003). A summary of all animal models tested and human clinical trials to date demonstrates that Ampligen exerts a greater antitumor activity than IFN and has a superior therapeutic ratio compared to rIn X rCn.

[Mutagenic activity of synthetic interferon inducers in laboratory mice]. / Issledovanie mutagennoi aktivnosti sinteticheskikh induktorov interferona na laboratornykh myshakh.

The mutagenic activity of poly(I) . poly(C) and poly(G) . poly(C) complexes in somatic and generative cells of mice was tested. Both preparations exhibited mutagenic activity in both test-systems. The poly(I) . poly(C) complex in the three doses tested was found to be more active both in bone marrow cells and in sex cells of male mice. The maximum effectiveness of this complex was demonstrated upon treatment of postmeiotic cells of males in an intermediate dose of 2.5 mg/kg bw. The rate of induced dominant lethals was 19.1%. In bone marrow metaphases the subtoxic dose of this complex increased 10-fold the control value of structural aberrations. The activity of poly(G) . poly(C) was found to be slightly lower.

[Trial of polyguacyl safety and tolerance]. / Ispytanie bezvrednosti i perenosimosti poliguatsila.

The results of studies of the antiviral and interferon-inducing activity of the synthetic interferon inducer polyguacyl in white mice as well as the results of the study of safety and tolerance of this drug given to human subjects as aerosol and intranasally are presented. Both modes of administration to mice induced production of endogenous interferon, although after intranasal inoculation high interferon titres in the blood serum of the animals were observed for longer periods of time, whereas after aerosol administration interferon disappeared more rapidly. Significant antiviral protection was achieved only by the intranasal administration of the inducer resulting in 84.0% survival of the animals challenged with the mouse-adapted influenza A/Aichi virus. Clinical trials of polyguacyl in human volunteers demonstrated the safety and good tolerance of this drug given both as aerosol and intranasally.

[Acute toxicity and cumulative properties of poly(I).poly(C) and poly(G).poly(C) polyribonucleotide complexes]. / Ostraia toksichnost' i kumuliativnye svoistva poliribonukleotidnykh kompleksov poli(I).poli(S) i poli(G). poli(Ts).

Acute experiments on mice and rats were made to determine the intraperitoneal lethal doses of the polyribonucleotide complexes poly (I).poly (C) and poly (G).poly (C) manufactured in this country. Changes in the function of cardiovascular, nervous, thermoregulatory and motor systems seen after injection of both complexes were shown to have some features in common but to differ in the rate and severity of poisoning. It was disclosed that the test polyribonucleotide complexes might be attributed to a group of substances that manifest the medium degree of cumulation.

Interferon induction by and toxicity of polyriboinosinic acid [poly(rI)].polyribocytidylic acid [poly (rC)], mismatched analog poly (rI).poly[r(C12Uracil)n], and poly(rI).poly(rC) L-lysine complexed with carboxymethylcellulose.

The ability of polyriboinosionic acid [poly(rI)].polyribocytidylic acid [poly(rC)], mismatched analog poly (rI).poly[r(C12Uracil)n], and poly(rI).poly(rC) complexed with poly L-lysine and carboxymethylcellulose [poly(ICLc)] to induce interferon and the comparative toxicity of each in cats were evaluated. Each induced high levels of circulating interferon, although poly(ICLC) injected intravenously at 1 to 4 mg/kg induced up to 10 times more interferon than the other compounds. Each compound was pyrogenic and caused a transient decrease in leukocyte numbers. Poly(rI).poly(rC) and the mismatched analog caused severe diarrhea and nausea at the highest drug concentrations (1 to 4 mg/kg), but poly (ICLC) did not. Each compound also caused depression and lethargy and impaired coordination.

[Comparative study of the toxicity of poly G-poly C and poly I-poly C in different objects]. / Sravnitel'noe issledovanie toksichnosti poli(G).poli(Ts) i poli(I).poli(Ts) na razlichnykh ob'ektakh.

The poly(G).poly(C) complex has the same interferon-inducing and antiviral activity upon parenteral administration to white mice as poly(I).poly(C), but is considerably less toxic. Upon intravenous inoculation of poly(I).poly(C) to mice its LD50 is 15.8 mg/kg whereas poly(G).poly(C) is not toxic in doses up to 200 mg/kg. In rabbits inoculated with poly(I).ploy(C) intravenously its LD50 is 0.22 mg/kg, while poly(G).poly(C) is not toxic in doses of 1 mg/kg. Histological examinations of different organs of mice and rats revealed no pathomorphological changes after a single intravenous and intraperitoneal inoculation of poly(G).poly(C). It exerted no embryotoxic effect in mice in a dose of 5 mg/kg and was considerably less toxic than poly(I).poly(C) in continuous diploid cell cultures of human embryo lung cells.

[Comparative antiviral and interferonogenic activity of synthetic polyribonucleotide complexes of poly(I).poly(C) and poly(G).poly(C) in different cell systems]. / Sravnitel'naia protivovirusnaia i interferonogennaia aktivnost' sinteticheskikh poliribonukleotidnykh kompleksov poli(I).poli(Ts) i poli(G).poli(Ts) v raznykh kletochnykh sistemakh

The antiviral and interferon-inducing activity of synthetic polyribonucleotide complexes poly(I)-poly(C) and poly(G)-poly(C) was studied in chick embryo, mouse embryo and rabbit kidney cell cultures. In chick embryo cell cultures both polyribonucleotides had similar antiviral activities. The interferon-inducing activity was more marked in poly(G)-poly(C) than in poly(I)-poly(C). In the other two cell cultures poly(I)-poly(C) was considerably superior in both activities. The revealed differences in the comparative activity of the polyribonucleotides in relation to the kind of tissue culture were not associated with differences between them in toxicity, sensitivity to pancreatic RN-ase or with possible differences in the duration of the contact with cells necessary for the achievement of the antiviral effect.

Induction of interferon by polyribonucleotides containing thiopyrimidines.

The influence of thioketo substitution in pyrimidine bases of double-stranded polynucleotides on interferon induction was investigated. The stabilizing effect of 2-thioketo substitution was reflected in the increased interferon inducing activity of poly(A-s2U) over that of poly(A-U). Poly(A-s2U) and poly(I)-poly(s2C) were as effective as poly(I)-Poly(C) in rabbit cells. Poly(I)-poly(C) and poly(I)-poly(s2C) were compared in several animal species. No differences in biological effects were observed in rabbits and dogs. In rodents, poly(I)-poly(s2C) was less effective and less toxic.Poly(I)-poly(s2C) was highly resistant against degradation by human serum. Further investigations seem to be justified to elucidate whether this property offers any advantages for the potential clinical utilization of poly(I)-poly(s2C).