Noncycling tumor cells are sensitive targets for the antiproliferative activity of human interferon.

Resting Burkitt's lymphoma cells (Daudi) in culture are more sensitive targets for the antiproliferative activity of purified human fibroblast interferon than cells that are rapidly multiplying. Thus, interferon may be of significant clinical value in neoplasms involving stem cells and, after chemotherapy, in suppressing the reemergence of tumors.

Friend leukemia: rapid development of erythropoietin-independent hematopoietic precursors.

Infection of mice with the polycythemia-inducing strain of Friend leukemia virus caused a rapid emergence of new erythroid precursor cells. These cells which, in the absence of erythropoietin, proliferated in vitro to form colonies and even differnetiated, quickly out-numbered the usual erythropoietin-dependent hematopoietic elements in bone marrow and spleen. Ultimately, the marrow and spleen were probably totally repopulated with this erythropoietin-independent cell.

Circulating colony-forming cells in different stages of chronic myelocytic leukemia.

The incidence of circulating granulocyte-macrophage colony-forming cells (CFU-c) was determined in 60 patients in different stages of chronic myelocytic leukemia (CML). Like others, we found uniformly increased circulating CFU-c during the uncontrolled chronic stage, decreasing to values indistinguishable from those of healthy controls during remission. Unlike some investigators who described grossly deficient colony formation during the blastic stage of CML, we found normal to greatly increased colony formation in the accelerated-resistant and blastic stages. The fact that laboratories using somewhat different culture techniques obtain similar results with specimens from the chronic stage of CML but divergent results with specimens from terminal stage disease suggests that CFU-c from blastic disease have more fastidious growth requirements than do those from chronic stage disease or from normal subjects. In contrast to the correlation between CFU-c and disease status in the chronic stage of CML, CFU-c incidence in the accelerated-resistant and blastic stages of the disease did not correlate with white blood cell count, percentage of immature cells, clinical status, or survival. There was no correlation between the percentage of myeloblasts and promyelocytes in circulating blood and the incidence of CFU-c in any stage of CML, which suggests that no direct relationship exists between clonogenic units and the number of identifiable proliferating cells.

Effect of methotrexate-monoclonal anti-prostatic acid phosphatase antibody conjugate on human prostate tumor.

Methotrexate (MTX) was conjugated to an immunoglobulin G1 (IgG1) monoclonal antibody specific for human prostatic acid phosphatase (PAP) by the active ester method. The molar ratio of MTX to IgG was 14. MTX-monoclonal antibody conjugate retained substantially the original PAP-binding inhibition activity of the monoclonal antibody. Both MTX-monoclonal antibody conjugate and an identically prepared MTX-normal mouse IgG conjugate preserved 90% of the original dihydrofolate reductase inhibitory activity of MTX. [3H]MTX conjugated to monoclonal anti-PAP antibody was significantly accumulated more in PAP-producing human prostate tumor LNCaP cells than its normal mouse IgG counterpart. No statistical difference was found between the uptake of [3H]MTX conjugated to monoclonal antibody and that of [3H]MTX conjugated to normal mouse IgG by control PAP nonproducing thyroid tumor cells (TT). The antitumor effect of the conjugate was evaluated in vitro by its inhibition on deoxy[6-3H]uridine incorporation into LNCaP cells. The inhibition by MTX-monoclonal antibody conjugate was significantly higher than that by MTX-normal mouse IgG conjugate at 8 micrograms of drug per ml, although it was significantly less than that by free MTX. However, an in vivo tumor and tissue distribution study of [3H]MTX and its conjugates revealed that, 5 days after i.v. administration, [3H]MTX conjugated to monoclonal antibody was preferentially accumulated in LNCaP prostate tumor. Tumor:blood ratios for [3H]MTX, [3H]MTX-monoclonal antibody conjugate, and [3H]MTX-normal mouse IgG conjugate were 1.47, 5.06, and 1.26, respectively. Preliminary results obtained from a pilot study with a small number of animals demonstrated that multiply injected MTX-monoclonal antibody conjugate retarded the growth of xenografted prostate tumor (LNCaP) as compared with the control groups, including free MTX which showed a shorter period of therapeutic effectiveness. This study suggests that MTX conjugated to monoclonal anti-PAP antibody could be a potential reagent for experimental immunochemotherapy of prostate tumor, should the initial in vivo data be extended and confirmed.

Isolation of prostatic acid phosphatase-binding immunoglobulin G from human sera and its potential for use as a tumor-localizing reagent.

A human immunoglobulin that binds prostatic acid phosphatases (PAP) was isolated from the serum of normal individuals by affinity chromatography using a PAP-Sepharose solid adsorbent. The yield of isolated protein, termed PAP-binding globulin (PAPBG), ranged from 4.7 to 16.3 microgram/ml serum. As shown by immunoelectrophoresis, PAPBG is a gamma-globin of restricted electrophoretic heterogeneity. PAPBG was shown to bind radiolabeled PAP by radioimmune precipitation, and an association constant of 5.0 x 10(4) M-1 was calculated. As determined by immunofluorescence, PAPBG was shown to react with human prostatic tumor cell lines. No binding was detected to other tumor cells examined including those from cultures of human breast, thyroid, pancreas, or normal fibroblasts.

LNCaP model of human prostatic carcinoma.

The LNCaP cell line was established from a metastatic lesion of human prostatic adenocarcinoma. The LNCaP cells grow readily in vitro (up to 8 x 10(5) cells/sq cm; doubling time, 60 hr), form clones in semisolid media, are highly resistant to human fibroblast interferon, and show an aneuploid (modal number, 76 to 91) human male karyotype with several marker chromosomes. The malignant properties of LNCaP cells are maintained. Athymic nude mice develop tumors at the injection site (volume-doubling time, 86 hr). Functional differentiation is preserved; both cultures and tumor produce acid phosphatase. High-affinity specific androgen receptors are present in the cytosol and nuclear fractions of cells in culture and in tumors. Estrogen receptors are demonstrable in the cytosol. The model is hormonally responsive. In vitro, 5 alpha-dihydrotestosterone modulates cell growth and stimulates acid phosphatase production. In vivo, the frequency of tumor development and the mean time of tumor appearance are significantly different for either sex. Male mice develop tumors earlier and at a greater frequency than do females. Hormonal manipulations show that, regardless of sex, the frequency of tumor development correlates with serum androgen levels. The rate of the tumor growth, however, is independent of the gender of hormonal status of the host.

Fibroblast interferon treatment of a patient with chronic active hepatitis. Increased number of circulating T lymphocytes and elimination of rosette-inhibitory factor.

A 23 year old woman with chronic active hepatitis documented by liver biopsy demonstrated persistent hepatitis B surface antigen, hepatitis B virus specific DNA polymerase hepatitis B core antigen (HBcAg), for approximately one year. The number of circulating T lymphocytes that rosetted with sheep erythrocytes was decreased, and a rosette-inhibitory factor was present in her peripheral blood. Interferon treatment (1 X 10(6) U/day intramuscularly for 82 days) resulted in a decrease of HBsAg and disappearance of HBcAg, (HBeAg) and specific DNA polymerase. In addition, the number of T lymphocytes increased to normal, and the rosette-inhibitory factor disappeared from the circulation. These findings suggest that the effect of interferon in chronic active hepatitis is mediated in part through its action on the immune system.

Purified human fibroblast interferon in vivo: skin reactions and effect on bone marrow precursor cells.

Human interferon from normal diploid fibroblasts, purified by sequential chromatography on concanavalin A-agarose and phenyl-sepharose, was administered parenterally in 4 subjects. Fever, marked skin hypersensitivity reactions and suppression of marrow stem cells (estimated by the count of myeloid colony-forming cells), side-effects common for less purified fibroblast and leukocyte interferons, were absent. Purified fibroblast interferon retained antiviral and immunomodulatory activity, evidenced by reduction of the blastogenic response of peripheral lymphocytes and decrease of hepatitis B virus markers in a patient with chronic hepatitis B infection treated with this substance.

Cell cultures derived from Wilms' tumour animal model.

Several cell cultures were established from a transplantable Wistar/Furth rat Wilms' tumour. Following cloning by the limiting dilutions method, three morphologically distinct types of cells were identified and preserved for further study of growth regulation in the nephroblastoma model.

Monoclonal antibodies to a new antigenic marker in epithelial prostatic cells and serum of prostatic cancer patients.

Stable clones of murine hybridomas 7E11-C5 and 9H10-A4 were obtained following immunization with LNCaP cells. The LNCaP cells were isolated from a human prostatic cancer (Ca). Both hybridomas secreted monoclonal antibodies (MoAb) of the IgG1 subclass which were reactive with the insoluble, cytoplasmic, membrane rich fractions of the immunogen. Neither MoAb reacted with the soluble cytosol of LNCaP cells nor with purified human prostatic acid phosphatase (PAP) nor prostate specific antigen (PSA). MoAb 9H10-A4 reactivity was very narrow and limited to the surfaces of LNCaP cells only. MoAb 7E11-C5 specificity was restricted to human prostatic epithelium, both normal and malignant. Except LNCaP, none of the 32 lines of human normal or neoplastic cells reacted with MoAb 7E11-C5. In a survey of frozen sections from 175 human specimens, positive indirect immunoperoxidase staining was limited to epithelium in all 11 specimens of localized and metastatic CaP, 7 benign prostatic hypertrophy (BPH) cases and 7 normal prostates. None of the 26 various nonprostatic tumors nor 120 out of 122 specimens from 28 different normal organs were reactive. Positive staining occurred in 2 out of 14 normal kidneys. Competitive binding with MoAb 7E11-C5 or its F(ab')2 fragments demonstrated the presence of circulating epitope 7E11-C5 in 20 out of 43 sera from CaP patients. Only 3 out of 66 sera from nonprostatic malignancies reacted. None of 30 normal blood donors sera nor 7 BPH sera were positive. Thus, highly significant (p less than 0.0001) association between diagnosed prostatic cancer and circulating molecules expressing the epitope reactive with MoAb 7E11-C5 was established. Significant probability (p less than 0.05) also suggested that patients with positive ELISA test are more likely to be in progression, than those who are negative. These results suggest that this apparently new antigenic marker may be of clinical potential in CaP.

Treatment of lymphoid neoplasias with interferon. I. Human fibroblastic beta-interferon in malignant gammapathies. Phase II trial.

18 patients with malignant gammapathies (16 with myeloma and 2 with Waldenström's disease) were treated with human fibroblastic Interferon (beta IF). This was administered i.v. 6 X 10(6) units weekly (7 patients) or 3 X 10(6) units twice weekly (11 patients). during at least 3 months if tolerated. Treatment was discontinued because of side effects in three patients. Reduction of the M component, by at least 25% from the initial value, was obtained in 3 patients. In one case the disappearance of a urinary Bence Jones protein was observed. In 4 cases, there was a significant reduction of bone marrow infiltration by plasma cells. In 5 cases, major alleviation or disappearance of bone pain was observed. Duration of treatment seemed to be an important factor for activity. Immune monitoring with currently available tests, mainly natural cytoxicity, yielded no correlation with therapeutic effect in these patients. This preliminary study demonstrates the effect of fibroblastic Interferon in myeloma. However, further studies are necessary to determine the population of patients most likely to benefit from treatment, the best modalities, possible special indications, dose schedules and duration of treatment. As it is not myelosuppressive it could be indicated in the frequent situation of advanced myeloma with bone marrow failure, contra-indicating combination chemotherapy.

Prospective new developments in laboratory research and clinical trials in prostatic cancer.

Laboratory research continues to develop new methods supporting clinicians in the management of prostatic cancer. Routine measurements of serum prostate-specific antigen (PSA) levels improve diagnosis, provide insight into tumor burden, and sharpen prognostication. New organ-specific antigenic targets are identified for monoclonal antibody-directed diagnostic and radiotherapeutic reagents. Such new immunospecific conjugates are already under evaluation in clinical trials. Cell culture techniques carry the promise of noninvasive early detection and prognostic evaluation of prostatic malignancy in preclinical stages. Molecular mechanisms responsible for androgen regulation of proliferation and malignancy of prostatic cancer are becoming open for scientific inquiry.

Responses of the murine myeloid colony-forming cell to ansamycin antibiotics.

The in vitro susceptibility of murine myeloid colony-forming cells to the antiproliferative activities of three ansamycin antibiotics was determined. These cells were found to be 10- to 40-fold more susceptible than the corresponding human ones.

Human interferon and its inducers: clinical program overview at Roswell Park Memorial Institute.

An overview of the clinical interferon program at Roswell Park Memorial Institute is presented. Purified fibroblast interferon and a novel inducer of human interferon [rIn-r(C12,U)n] are being evaluated for possible antiviral, antiproliferative, and immunomodulatory activities in patients with cancer.

Differential susceptibility of spleen focus-forming virus and murine leukemia viruses to ansamycin antibiotics.

The streptovaricin complex (SvCx) and rifamycin SV derivatives display potent antiviral activity against the polycythemic strain of Friend leukemia virus (FV-P), as measured by a reduction in the number of spleen foci produced in mice. Such reductions may be explained by inactivation of functions of (i) the spleen focus-forming virus (SFFV), (ii) its "helper" murine leukemia virus (MuLV), or (iii) both viruses normally present in FV-P. We noted that preincubation of FV-P with fractionation products of SvCx, or derivatives of rifamycin SV, at low concentrations (3 to 5 mug/ml) reduces the number of spleen foci 80 to 97%, whereas titers of MuLV (from the same inoculum) remain unaffected (MuLV titers were measured by XC, S(+)L(-), and "helper activity" assays). Our findings indicate a remarkable biological selectivity of ansamycins, as well as nonansamycin components of SvCx, against the transforming and defective spleen focus-forming virus as compared to MuLV. Thus, the drugs might be useful in distinguishing other types of oncornaviruses.