Poly ICLC

The above data were obtained in solutions approximately 10 M, or a few micrograms per ml. When attempts were made to prepare solutions of higher concentrations,a heavy gummy precipitate was obtained. However, it one first forms a complex between poly-lysine and carboxymethylcellulose and then adds poly I poly C, a soluble material is obtained. This material, poly(ICLC), is thermodynamically more stable than poly I-poly C, as shown in thermal denaturation studies (Fig. 3). These studies were done in O.IX SSC, as poly(ICLC) did not "melt" below lOO C in SSC. The new compound is more resistant to hydrolysis by human sera or RNase than is poly I poly C (Fig. 4). Poly(ICLC) induces 5-10 times more interferon in mice than does poly I poly C (Levy et al., 1975a). 

The important difference between poly I poly C and poly(ICLC) is that the latter is able to induce significant quantities of interferon in primates. Figure 5 shows representative interferon induction kinetics in two Rhesus monkeys. In studies designed to determine the lethal dose of poly(ICLC) in monkeys (20 to 40 mg/kg body weight), up to 200,000 units of interferon per ml of serum were found. 

Fig. 3. Thermal denaturation of poly I-poly C and the poly-L-lysine complex of poly I poly C (poly [iCLC]). The compounds, at a concentration of 50 yg poly I poly C/ml in 0.1 x standard saline-citrate, were heated to the indicated temperatures in a recording spectrophotometer set at 260 mm (T ).

It can be seen that as the size of the d.s. RNA increases so does the T increase, from about 84 C for 4S to 88.5 C for the 9S complex. he resistance to hydrolysis by RNase A is also increased as the size is increased. The 4S complex is nearly totally hydrolysed by RNase, whereas 9S complex is only hydrolysed about 7.8% (increase in A , ). The interferon-inducing capacity can be seen to increase significantly as the size of the molecule increases. 4S poly(ICLC) induces very little interferon in monkeys whereas 9S poly(ICLC) induced greater than 1,000 units. 

Table 1. Correlation Between Homopolymer Size, Hydrolysis and Interferon Induction in Monkeys by poly(ICLC)...

Molecular weight of poly-L-lysine Hydrolysis pf poly(ICLC)— Peak serum interferon Levels (log units/ml)... 

It is not unreasonable to consider that poly(ICLC) in primates is like poly I poly C in rodents, with poly(ICLC) being effective in primates because of its ability to resist the increased hydrolytic activity of primate serum. All the subsequent studies presented here were done with poly(ICLC) made with 9S poly I poly C, and 27,000 dalton M.W. of polylysine. 

Fig. 5. Kinetics of induction of serum interferon in rhesus monkeys by i.v. administration of 3 or 5 mg/kg poly (ICLC) (one monkey per dose).

Table 3. Effect of Poly(ICLC) and Human Diploid Cell Vaccine 48 Hours After Rabies Infection in Rhesus Monkeys...

Table 4 gives a list of virus infections in monkeys that have been treated systemically with poly(ICLC). With the exception of Bolivian hemorrhagic fever and Tacaribe virus, all have been benefited. 

Poly(ICLC) induces the formation of adequate levels of interferon in chimpanzees (Purcell et al., 1976). There is a model of chronic hepatitis B in young chimpanzees. When chimpanzees were injected with poly(ICLC) at 1 mg/kg body weight, they produced up to 750 units of interferon per ml of serum. When hepatitis B carriers were treated with poly(ICLC) evidence of the virus disappeared during the 16 week treatment, but reappeared after treatment was terminated (Fig. 6). Whether or not really prolonged treatment would have a more permanent effect has not been determined. 

Poly(ICLC) has proven to be a good immune adjuvant in primates. When used in conjunction with a number of weak vaccines, the action of the vaccine has been strongly augmented. Among the vaccines are those to Venezuelan equine encephalomyelitis (Harrington et al.,... 

Table 4. Virus Diseases of with Poly(ICLC) Animals that Have Been Treated...

Venezuelan equine encephalitis Monkey Using a nonlethal virus challenge poly(ICLC) reduced viremia by 50% Stephen et al. (1979)... 

Tacaribe virus Mice No effect by poly (ICLC) Stephen, unpublished observation... 

HAI ANTIBODY RESPONSE OF YOUNG MONKEYS GIVEN 200 CCA UNITS OF SWINE INFLUENZA VACCINE WITH POLY(ICLC) AS ADJUVANT (N = 4)... 

Fig. 7. Effect of one injection of poly(ICLC) on antibody production by rhesus monkeys in response to a subunit vaccine to swine flu (four monkeys per group).

Analogous results were obtained in monkeys using inactivated Venezuelan equine encephalomyelitis virus vaccine (Harrington et al., 1979). Figure 8 shows some of the data. It can be seen that antibody levels in serum were boosted about 40-fold after primary immunization when one compares levels attained after administration of vaccine along with poly(ICLC) with that attained with vaccine alone, and perhaps 200-fold after a secondary immunization. There was no alteration in the progression of IgM and IgG development. At the peak of antibody levels, most of the antibody was IgG. Polylysine complexed to carboxymethylcellulose, without poly I poly C, had no adjuvant action. 

The value of 100 was assigned in each case to the amount of radioactivity found using the serum obtained prior to immunization. The vaccine alone caused a minimum boost, but when given with poly(ICLC) there was a more pronounced boost. Polyadenylic polyuridylic acid complexed to carboxymethylcellulose and polylysine was not so effective as poly(ICLC). Poly(ICLC) is not a universal adjuvant. With albumin and pneumococcal polysaccharide antigen, there was inhibition of antibody production (Levy, unpublished observations). 

Fig. 8. Serum neutralizing antibody response by immunoglobulin class of rhesus monkeys inoculated on days 0 and 28 with (A) inactivated VEE virus vaccine (n=4), or (B) vaccine combined with 200 yg of poly(ICLC)/kg (n=4). Symbols (A) whole serum antibody titers, (o) antibody from IgG fraction, ( ) antibody from IgM fractions.

Table 6. Mean Peak Serum Interferon Titers After Treatment with Poly(ICLC)...

The Children s Hospital Cancer Testing Group (Lampkin and Levy, unpublished observations) has looked at the effect of poly(ICLC) on... 

It can be seen that surgery was required less and less frequently after treatment with poly(ICLC) bggan. The regimen for these patients consisted of initiation at 4 mg/m and working up to 12 or even 15 mg/m over several weeks. 

Fig. 9. Effect of poly(ICLC) on frequency of surgical intervention in juvenile laryngopapilloma in a child. Each dot represents one surgical intervention.

K decrease In B-J excretion, plus correction of hypercalcemia and disease stabilization with first period of treatment. 44% decrease In B-J excretion when poly (ICLC) restarted 2 months later. Normocalcemic for 5 months. 

Died one week after Initiation of poly (ICLC). 

Fig. 11. Types of neurologic diseases treated with poly(ICLC).

Krown, S., Oetgen, H., Stewart, W., and Levy, H.B., 1980, Phase I trial of poly ICLC in cancer patients. In Chirigos M (ed) Proceedings of symposium on biological modifiers in treatment of cancer, March, 1980, Raven Press, New York. 

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