Antitumor effect of forphenicinol, a low molecular weight immunomodifier, on murine transplantable tumors and microbial infections

Forphenicinol enhances the antitumor effects of cyclophosphamide in a model of squamous cell carcinoma

We examined the interaction between forphenicinol (FPL) and cyclophosphamide (CPA) or ionizing radiation (IR) on the growth of murine squamous cell carcinoma tumors SCCVII. Primary tumors were established in C3H mice by injecting SCCVII tumor cells subcutaneously into the right hind limb. FPL (100 mg/kg for 8 days) and/or CPA (25 mg/kg twice) were administered by intraperitoneal injection. Tumors were irradiated to a total dose of 40 Gy (eight 5-Gy fractions). SCCVII tumor growth was inhibited by FPL (P=0.054), IR (P=0.003) and CPA (P<0.001) compared with control. The combination of FPL and CPA inhibited tumor growth additively compared with either treatment alone in both small- and large-volume tumors. FPL did not significantly enhance the antitumor effects of IR, however, when CPA+FPL were combined with IR, significant tumor growth inhibition was observed compared with FPL alone (P<0.001), CPA alone (P=0.002) and IR alone (P=0.002). Due to its low toxicity profile, FPL may be combined with CPA, IR and other cytotoxic therapies to potentially enhance the therapeutic ratio.

Low molecular weight immunomodulators produced by microorganisms

In order to develop a new class of low molecular weight immunomodulators for the treatment of incurable diseases involving cancer, hematologic diseases and inflammation, we have sought cytokine inducers and inhibitors of cell adhesion to the extracellular matrix among the low molecular compounds produced by microorganisms. Cytogenin, cytoblastin (a monokine inducer), conagenin (a lymphokine inducer) and delaminomycins and IC-101 (inhibitors of cell adhesion to extracellular matrices) have been recently found in our institute. In this report, we describe the principles of screening and structures, and discuss their biological activities.

Immunomodulators isolated from microorganisms

Microbial products are surveyed that have an immunoregulatory activity, both from the realm of low-molar-mass compounds and from the group of naturally occurring polymers. The data include in most cases the producer organism or source, a brief chemical characteristic and biological activity. Various groups of substances are compared, the drawbacks attendant on their acquisition and application are pointed out and their advantageous properties are specified.

High-performance liquid chromatographic determination of forphenicine in mouse serum and muscle by pre-column fluorescence derivatization using 1,2-diamino-4,5-ethylenedioxybenzene as fluorogenic reagent

A simple and sensitive high-performance liquid chromatographic method has been developed for the determination of forphenicine in biological samples. Forphenicine in the deproteinized sample is converted by reaction with 1,2-diamino-4,5-ethylenedioxybenzene into a fluorescent derivative. The derivative is separated on a reversed-phase column (TSK gel ODS-120T) by isocratic elution with acetonitrile-30 mM phosphate buffer (pH 6.5) (5:1, v/v) and monitored fluorimetrically. The method allows the quantification of forphenicine in serum (100 microliters) and muscle (0.1 g) of mice dosed with forphenicine or forphenicinol. The limits of detection (signal-to-noise ratio of 3) are 7.35 pmol/ml in serum and 5.36 pmol/g in muscle. The distribution of forphenicine and forphenicinol in the mouse serum and muscle after oral administration of these compounds is also described.

Low molecular weight immunopotentiators

It has long been recognized that modulation of the immune system by various agents may have potential for the management of certain infectious and neoplastic diseases. Both natural products as well as chemically synthesized compounds have been investigated for immunotherapeutic potential. Over the years, conflicting reports on the clinical efficacy of these agents have left the early promise of immunotherapy unfulfilled. However, the manipulation of the immune system to generate a desired effect is becoming feasible as the mechanisms which regulate the immune network are better understood. Much of the early work on immunotherapy concentrated on the development of immunopotentiators, agents which enhance the host's own immune system against cancer cells or infectious pathogens. Furthermore, with the development of subunit and/or synthetic vaccines, which are often weakly immunogenic, the importance of developing agents capable of acting as adjuvants became apparent. As a result, the utility of immunopotentiators has now extended to the area of vaccines. There are a number of reviews available on immunomodulators [see Fenichel, R. L. and Chirigos, M. A. (eds) (1984), Immune Modulation Agents and Their Mechanisms, Marcel Dekker, New York]. The purpose of this article is to provide an update on low molecular weight agents capable of potentiating the immunological network. Attention will be given to those agents which have undergone significant clinical development in the areas of cancer, infectious diseases and vaccination over the past several years. These agents will be categorized as to whether they are naturally occurring or chemically synthesized.

Comparative efficacy of forphenicinol, cyclosporine, and amphotericin B in experimental murine coccidioidomycosis

Cohorts of ten mice, uninfected and infected (intratracheal injection of coccidioidal arthroconidia), were treated for 23 days by intravenous injections of either 5% glucose solution, an immunostimulant (forphenicinol), an immunodepressant (cyclosporine), or amphotericin B. All mice were autopsied (survivors at 26 days postinoculation) and suspensions of lungs, livers, and spleens were cultured. All uninfected animals survived and gained weight, whereas, only 20% of the infected controls survived, and all lost weight. Treatment with forphenicinol had no effect on survival or weight. Cyclosporine secured 90% survival at the lowest dose and 60% at the higher doses, with no net loss of weight; however, all cultures of organs yielded heavy growth of Coccidioides immitis. With amphotericin B, all mice survived and gained weight; four mice from each of the two treatment groups yielded modest growth of C. immitis from the lungs, and one mouse of each group yielded sparse growth from liver and spleen. The paradox of no effect from an immunostimulant and therapeutic effect from an immunodepressant correlated with susceptibility testing of C. immitis in vitro.

Simple determination of forphenicinol in human plasma and erythrocytes by HPLC with native fluorescence detection

A high performance liquid chromatographic method is described for monitoring forphenicinol, a possible therapeutic drug for cancer and muscular dystrophy, in human plasma and erythrocytes. Forphenicinol in the deproteinized samples was separated from interfering biogenic substances on an aminopropyl-bonded silica (Unicil NH2) column within 10 minutes with isocratic elution, and determined with fluorescence detection. The detection limits for forphenicinol in plasma and erythrocytes are 65 pmol (12.8 ng)/ml and 160 pmol (31.5 ng)/ml, respectively, corresponding to 2 pmol each in a 100 microliters injection volume. The method is very simple, and sensitive enough to permit the quantification of forphenicinol in the blood samples from man dosed with forphenicinol.