Acute myelogenous leukemia: current status of therapy in adults.
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Publications and source records attributed to K A Foon.
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The need for improved specificity in cancer therapy is apparent. With the advent of monoclonal antibodies, the possibility of specifically targeted therapy is here. Early trials with monoclonal antibody in experimental animals and in man have demonstrated antibody can travel to specific tumor sites and localize on or around the tumor cells displaying antigens to which the antibody is directed. This evidence of specific targeting, along with early evidence of therapeutic efficacy for monoclonal antibodies and antibody immunoconjugates with drugs, toxins and isotopes, is encouraging. Some preliminary clinical observations from two monoclonal antibody trials are presented and the current status of clinical trials with monoclonal antibodies is reviewed.
Biochemical and clinical signs of tumor lysis syndrome developed in a 57-year-old man with recurrent T cell lymphoma during therapy with recombinant leukocyte A interferon. When therapy was interrupted due to thrombocytopenia and later resumed, biochemical changes compatible with tumor lysis recurred. This is the first case of tumor lysis syndrome observed during therapy with a biologic response modifier, a new class of agents entering cancer clinical trials. The atypical features of the clinical presentation and possible implications of these observations are discussed.
Two patients with advanced lymphoma involving the lungs that was resistant to chemotherapy had an initial excellent response to interferon therapy. After two months of stable disease, alpha interferon A therapy was discontinued, with relapse of a few months later. Both patients had extensive pulmonary involvement with relapse of the lymphoma, and both showed a dramatic response to retreatment with alpha interferon A. Unusual interferon-related pulmonary complications were observed in one patient, and their management is detailed.
Monoclonal antibodies to tumor-associated antigens (TAA) of human colorectal cancer were elicited using immunosorbents of lectins combined with peripheral protein extracts of xenografted colon adenocarcinoma. This method of immunization was compared with whole cells from surgical specimens and to crude membranes from xenografted tumors. The immunosorbent immunogens were superior to the other immunogens in three ways: (1) the number of hybrids reactive with colon tumor cells or extracts, but not with lymphoid cells or extracts, (2) the number of stable hybrids after cloning, and (3) the number of hybridoma clones reactive with tissue sections of colon tumors, but not normal colonic mucosa. In addition, lectin immunosorbents elicited primarily IgG antibodies, especially IgG3, with almost 50% of the clones of interest reacting to seemingly less immunogenic glycoproteins. The improved elicitation of monoclonal antibodies to TAA by the use of lectin immunosorbents and peripheral protein extracts has considerable potential for generating reagents useful in diagnosis and therapy of human tumors.
Mice were immunized with purified human monocytes or granulocytes obtained by leukapheresis and isolated on dextran gradients or by countercurrent centrifugation-elutriation. A monoclonal antibody, Mo95, was generated in response to monocytes and was found to react strongly with monocytes, large granular lymphocytes (LGL), granulocytes, eosinophils, and some myelomonocytic leukemia cells, but not with normal T or B lymphocytes, platelets, red cells, or leukemic cell lines. Mo95 is an IgG1 antibody, which precipitated a 95 kD molecular weight antigen. Addition of the Mo95 antibody to monocytes in the absence of complement did not inhibit lysozyme secretion nor did it affect superoxide production, C3b-rosetting, nitrotetrazolium blue reduction, phagocytosis, or chemotactic responses. A second antibody, PMN70, was found to react exclusively with granulocytes and not with monocytes, lymphocytes, LGL, platelets, red cells, or any of the myelomonocytic, T-cell-derived or B-cell-derived leukemic cell lines tested. The PMN70 antibody immunoprecipitated a 70 kD molecular weight antigen found only on mature granulocytes. Mo95 and PMN70 appear to be distinct from five other tested monoclonal antibodies reactive to monocytes and/or granulocytes on the basis of the fluorescent cell sorter and immunoprecipitation studies performed.
The murine antimelanoma monoclonal antibody, 9.2.27, was administered intravenously to eight patients with metastatic malignant melanoma. Biopsies of metastatic nodules clearly demonstrate the selective localization of this antibody on the melanoma cell surface with a dose-response relationship to the quantity of administered antibody. The antibody infusions were clinically well tolerated and the pharmacokinetics of the antibody and the antiglobulin responses are described. This study indicates that murine monoclonal antibodies have potential as selective targeting agents in the design of future therapeutic trials using monoclonal antibodies or conjugates thereof in the treatment of cancer.
Extensive immunologic studies were done in 97 patients with severe aplastic anemia between 1973 and 1979. Sixteen young male patients with hepatitis-associated aplastic anemia appeared to constitute a unique subset. Compared with most patients with aplastic anemia from other causes, these 16 patients had significant reductions in the mean values of circulating T lymphocytes, serum IgG and IgM, mitogen reactivity, and decreased cutaneous hypersensitivity. The ratio of peripheral blood helper to suppressor T lymphocytes identified by monoclonal antibodies was within normal limits in 3 patients studied with hepatitis-associated aplastic anemia. Interestingly, the ratio was low (less than 1) in 3 of 7 patients studied with aplastic anemia from other causes, although the mean for these 7 patients was normal. These data suggest that patients in this subset with hepatitis-associated severe aplastic anemia have a severe immunodeficiency. Whether this immunodeficiency is the cause or result of the hepatitis or aplastic anemia, or both, is unknown.
High-dose recombinant leukocyte A interferon (50 X 10(6) U/m2 body surface area, intramuscularly, three times weekly) was tested in a clinical trial involving patients with advanced cutaneous T-cell lymphomas to determine its effectiveness and toxicity. All 20 patients had advanced stages of disease refractory to two or more standard therapies. Objective partial remissions lasting 3 months to more than 25 months (median, 5 months) were documented in 9 patients. The major dose-limiting toxicity was a severe influenza-like syndrome with malaise, anorexia, depression, weight loss, and decreased performance status; this effect was reversible after dose reductions in all patients and did not recur with re-escalation of doses in 10 patients. This interferon preparation is highly effective in the treatment of advanced refractory cutaneous T-cell lymphomas, and new schedules to reduce toxicity and achieve complete responses, combined treatment with chemotherapy or serotherapy, and its use in earlier stages of disease should be investigated.
T gamma lymphocytes are those lymphocytes that express receptors for both the Fc portion of IgG and sheep erythrocytes. A very high proportion of normal T gamma lymphocytes are large granular lymphocytes (LGL), the cell responsible for most, if not all, natural killer (NK) and antibody-dependent cell-mediated cytotoxicity (ADCC) in humans, rats, and mice. In general, these cells are large lymphocytes with prominent azurophilic granules in the cytoplasm. Recently, a group of lymphoproliferative disorders made up predominantly of T gamma lymphocytes has been described. The most common and best studied of these disorders we refer to as "chronic T gamma-lymphoproliferative disease" (T gamma-LPD). In most cases, this disease represents the abnormal expansion of LGL, which is reflected by an increase in functionally active NK or ADCC effector cells. The chronic T gamma-LPD lymphocytes are generally characterized as E- and EA-rosette positive, acid-phosphatase, and beta-glucuronidase positive and express the pan-T antigens OKT3/Leu-4, OKT11/Leu-5, the suppressor-associated antigens OKT5,8/Leu-2, and the NK-associated antigens Leu-7/HNK-1. Typically, the patients are older, predominantly males and characteristically have a lymphocytosis of predominantly T gamma lymphocytes with lymphocyte infiltration of the bone marrow and often the spleen. While chronic T gamma-LPD is not usually an aggressive disease, the patients are often neutropenic and have recurrent bacterial infections requiring antibiotic therapy. Some patients have benefited from cytotoxic chemotherapy., but most patients have not required chemotherapy. An experimental LGL leukemia in F344 rats appears morphologically, functionally, and clinically similar to the human chronic T gamma-LPD and serves as an experimental model for further examining the ontogeny and function of LGL and may be applicable for exploring new and more effective means for the treatment of patients with chronic T gamma-LPD.
A phase I clinical trial was initiated to treat patients with stage IV B-derived chronic lymphocytic leukemia (CLL) with the IgG2a murine monoclonal antibody T101. This antibody binds to a 65,000-mol wt (T65) antigen found on normal T lymphocytes, malignant T lymphocytes, and B-derived CLL cells. All of the patients had a histologically confirmed diagnosis of advanced B-derived CLL and were refractory to standard therapy, and more than 50% of their leukemia cells reacted with the T101 antibody in vitro. The patients received T101 antibody two times per week, over two to 50 hours by intravenous administration in 100 mL of normal saline containing 5% human albumin. Twelve patients were treated with a fixed dosage of 1, 10, 50, or 100 mg, and one patient was treated with 140 mg of antibody. It was demonstrated that patients given two-hour infusions of 50 mg developed pulmonary toxicity, with shortness of breath and chest tightness. This toxicity was eliminated when infusions of 50 or 100 mg of T101 were prolonged to 50 hours. All dose levels caused a rapid but transient decrease in circulating leukemia cell counts. In vivo binding to circulating and bone marrow leukemia cells was demonstrated at all dose levels with increased binding at higher dosages. Antimurine antibody responses were not demonstrated in any patients at any time during treatment. Circulating free murine antibody was demonstrated in the serum of only the two patients treated with 100 mg of antibody as a 50-hour infusion and the patient treated with 140 mg of antibody over 30 hours. Antigenic modulation was demonstrated in patients treated at all dose levels but was particularly apparent in patients treated with prolonged infusions of 50 and 100 mg of antibody. We were also able to demonstrate antigenic modulation in lymph node cells, which strongly suggests in vivo labeling of these cells. Overall, T101 antibody alone appears to have a very limited therapeutic value for patients with CLL. The observations of in vivo labeling of tumor cells, antigenic modulation, antibody pharmacokinetics, toxicity, and antimurine antibody formation may be used in the future for more effective therapy when drugs or toxins are conjugated to the antibody.
Antigenic modulation of the T65 cell surface antigen was assessed in chronic lymphocytic leukemia patients (CLL) receiving therapy with the murine monoclonal antibody T101 in a phase I clinical trial. A total of 12 patients received 1, 10, or 40 mg doses administered over 2 hr, or 50 or 100 mg doses administered over 50 hr. Decreases in T65 antigen expression (up to 90%) coincided with decreases in the circulating leukemic cell count in those patients who received T101 over a 2-hr period, indicating that clearance of circulating T65 antigen-positive cells could account for most of the observed decreases in T65 antigen expression. In contrast, analysis of bone marrow specimens from these patients indicated that decreases in T65 antigen density in this relatively stationary population resulted not from a cell decrement but rather from antigenic modulation. Pulmonary toxicity prevented administration of doses greater than 40 mg over a 2-hr period; therefore, higher doses (50 and 100 mg) were administered over a 50-hr period. This treatment schedule resulted in greater than 90% reduction in T65 antigen density of both circulating and bone marrow leukemic cells without dramatic drops in circulating leukemic cell counts, indicating that antigenic modulation accounted for most of the observed decreases in T65 antigen density under these conditions. Reexpression of T65 antigen by modulated cells was observed both in vitro and in vivo within 2 to 4 days. Immunoperoxidase staining of in vivo-modulated specimens and in vitro modulation studies with 125I-T101 suggested that T65 antigen-T101 antibody complexes were internalized during modulation. Although antigenic modulation inhibits the potential therapeutic effectiveness of unconjugated T101 antibody in CLL patients, treatment of CLL with T101 drug or toxin immunoconjugates under conditions that bring about rapid and extensive internalization of the T65 antigen may provide an effective means of therapy.
Thirty-three patients were treated in an escalating single-dose trial of partially purified nonrecombinant interferon-gamma (IFN-gamma). The first seven patients received intramuscular injections of IFN-gamma in doses up to 20 X 10(6) units/m2. When it became clear that these patients had no detectable antiviral activity in their serum, subsequent patients were treated by the intravenous route of administration, generally with 2-h infusions. A total of 26 patients received the agent intravenously in single escalating doses ranging from 0.2 to 60 X 10(6) units/m2, on a twice-weekly schedule for 4-6 weeks. The most common toxicities encountered included fever, chills, fatigue, anorexia, and occasional nausea and vomiting. No myelosuppression or hepatic toxicity was observed. A maximum tolerated dose for single-dose intravenous administration was defined as 50 X 10(6) units/m2 on the basis of unacceptable fatigue and prolonged systolic hypotension. Antiviral activity was detected in the serum following doses greater than 2 X 10(6) units/m2 when the IFN-gamma was administered intravenously. No evidence of antitumor activity was seen in this Phase I trial, although the treatment regimen employed did not lead to high or prolonged levels of serum IFN activity in the majority of patients. An accurate assessment of the antitumor activity of this particular IFN-gamma preparation will require Phase II trials employing multiple-treatment regimens.
The toxic A chain of abrin was isolated by affinity chromatography and was demonstrated to be a potent inhibitor of protein synthesis in a cell-free rabbit reticulocyte system with a complete inhibitory dose at 1 X 10(-9) M. This A chain was coupled by a disulfide linkage to a purified monoclonal antibody directed against a tumor-associated antigen found on the line 10 hepatocarcinoma tumor in strain two guinea pigs. The immunoconjugate retained the functions of the individual components, i.e., antigen binding to the intact cell in vitro and inhibition of its protein synthesis. This conjugate was a selective antineoplastic agent with a cytocidal dose at 5 X 10(-9) M toward antigen-bearing cells in vitro. Several antigen-negative cells were much less susceptible to its cytotoxic effect. The cytotoxicity of the conjugate appeared to be by antibody-mediated delivery of toxic A chain into the target cell. When cells were pretreated with excess free antibody followed by a brief exposure to conjugate, there was a reversal of the cytotoxicity to antigen-positive cells but not to the antigen-negative cells. The therapeutic efficacy of the conjugate was assayed by injecting a single dose s.c. or i.v. into syngeneic guinea pigs bearing established line 10 tumors. These in vivo studies showed that (a) the conjugate was not toxic at a dosage of 60 to 1120 micrograms/guinea pig, (b) the conjugate decreased or abolished the growth of established solid tumors, (c) the conjugate delayed or inhibited tumor metastases to lymph nodes, and (d) 20 to 40% of the animals in selective groups had a long-term complete regression.
Human-murine hybridomas, generated by fusion of human CLL cells with non-Ig-secreting murine myeloma NS-1, and secreting the IgM kappa expressed on the CLL cell surface, were grown in the peritoneal cavity of doubly pristane-primed nude mice to produce large quantities of highly concentrated human IgM kappa for the development of anti-idiotype monoclonal antibodies. Although the hybridomas secreted only 0.8 to 1.5 micrograms/ml/10(6) cells in tissue culture, they produced 8 to 12 ml of ascites from two mice containing 1.7 mg/ml of human IgM. Partial purification was then easily accomplished by euglobulin precipitation. Two weekly injections of 100 micrograms of this material into BALB/c mice resulted in the development of both anti-idiotypic and anti-human IgM antibodies. This system overcomes the major hurdle of generating sufficient quantities of the human idiotypic Ig to immunize and screen for specific murine antiidiotypes, and provides the material to produce these therapeutically promising reagents rapidly for clinical trials. This is, to our knowledge, the first report of a human Ig produced in mouse ascites.
Highly purified human lymphoblastoid interferon (HLBI) derived from virus-stimulated Namalwa cells was administered by 6-h IV infusion or IM injection to 40 patients with a variety of disseminated malignancies refractory to standard therapy. Each patient received doses escalating from 0.1 to 50 X 10(6) U for up to 5 weeks. Extensive monitoring for clinical effect, toxicity, and pharmacokinetics has revealed higher peak serum interferon levels and somewhat more pronounced systemic toxicity for the IV than for the IM route of administration. Objective evidence of tumor regression was observed in two patients receiving HLBI IV.
Mice were immunized with purified eosinophils obtained from patients with the idiopathic hypereosinophilic syndrome. A hybridoma initially producing an IgM antibody which switched to an IgG1 antibody was selected for cloning and further testing. This IgG1 antibody reacted with human eosinophils, granulocytes, monocytes and large granular lymphocytes, but did not react with T lymphocytes, B lymphocytes, platelets, erythrocytes, or a panel of human leukemia cells and cell lines. Bone marrow analysis revealed staining of myeloid precursor cells but not erythroid precursors or plasma cells. This IgG1 antibody had no effect on aggregation of granulocytes, lysozyme release, superoxide production, chemotaxis, or killing activity; however, there was some stimulation of beta-glucuronidase secretion. While the antibody did not augment the killing of Staphylococcus aureus by granulocytes, the antibody itself was bactericidal. By immunoprecipitation of granulocytes, eosinophils and monocytes, a molecule with a molecular weight of 95 kD was identified.
Nineteen patients with advanced refractory metastatic breast cancer no longer responsive to chemotherapy were treated in the first phase II efficacy trial of recombinant leukocyte A interferon (IFL-rA), a highly purified single molecular species of alpha interferon prepared by recombinant DNA methods. Patients received a previously determined maximum tolerated dose for this agent (50 X 10(6) U/m2 body surface area) by intramuscular injection three times weekly for up to 3 months. The symptoms of toxicity observed in this trial resemble those previously reported for alpha interferons and include fever, chills, fatigue, anorexia, and leukopenia. All patients required dose reductions, most often for reasons of severe fatigue. Of the 17 patients evaluable for tumor response, one patient had stable disease and 16 had evidence of tumor progression. We conclude that IFL-rA is not an active agent in the treatment of advanced, refractory breast cancer when used at a maximum tolerated dose on this treatment schedule.