C. Patrick Burns

The role of radiation therapy in the treatment of solitary plasmacytomas

Between 1960 and 1985, 30 patients with solitary plasmacytomas were treated with radiotherapy at the University of Iowa: 13 patients with extramedullary plasmacytomas (EMP) and 17 with solitary plasmacytomas of bone (SPB). The local control rates were 92% for patients with EMP and 88% for those with SPB. Two of nine patients (22%) with EMP treated to the primary tumor only developed regional lymph node metastasis, indicating the need for elective irradiation of this area. The most common pattern of failure in both groups was progression to multiple myeloma. This occurred in 23% of the patients with EMP and 53% of those with SPB. The time course of progression to multiple myeloma differed for the two groups. All of those who progressed to multiple myeloma in the EMP group did so within 2 years, whereas a significant number of those in the SPB group progressed more than 5 years after initial therapy. None of five patients who received adjuvant chemotherapy in the SPB group progressed to multiple myeloma, compared to 75% (9/12) of the patients who did not receive chemotherapy.

Phase II study of high-dose fish oil capsules for patients with cancer-related cachexia.

The authors undertook a multiinstitutional Phase II cooperative group study to examine the potential of oral fish oil fatty acid supplements administered at high doses to slow weight loss and to improve quality of life in patients with malignancy‐related cachexia.

Myeloperoxidase Is Involved in H2O2-induced Apoptosis of HL-60 Human Leukemia Cells

We examined the mechanism of H2O2-induced cytotoxicity and its relationship to oxidation in human leukemia cells. The HL-60 promyelocytic leukemia cell line was sensitive to H2O2, and at concentrations up to about 20–25 μm, the killing was mediated by apoptosis. There was limited evidence of lipid peroxidation, suggesting that the effects of H2O2 do not involve hydroxyl radical. When HL-60 cells were exposed to H2O2 in the presence of the spin trap α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN), we detected a 12-line electron paramagnetic resonance spectrum assigned to the POBN/POBN⋅ N-centered spin adduct previously described in peroxidase-containing cell-free systems. Generation of this radical by HL-60 cells had the same H2O2concentration dependence as initiation of apoptosis. In contrast, studies with the K562 human erythroleukemia cell line, which is often used for comparison with the HL-60, and with high passaged HL-60 cells (spent HL-60) studied under the same conditions failed to generate POBN⋅. Cellular levels of antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase did not explain the differences between these cell lines. Interestingly, the K562 and spent HL-60 cells, which did not generate the radical, also failed to undergo H2O2-induced apoptosis. Based on this we reasoned that the difference in H2O2-induced apoptosis might be due to the enzyme myeloperoxidase. Only the apoptosis-manifesting HL-60 cells contained appreciable immunoreactive protein or enzymatic activity of this cellular enzyme. When HL-60 cells were incubated with methimazole or 4-aminobenzoic acid hydrazide, which are inhibitors of myeloperoxidase, they no longer underwent H2O2-induced apoptosis. Hypochlorous acid stimulated apoptosis in both HL-60 and spent HL-60 cells, indicating that another oxidant generated by myeloperoxidase induces apoptosis and that it may be the direct mediator of H2O2-induced apoptosis. Taken together these observations indicate that H2O2-induced apoptosis in the HL-60 human leukemia cell is mediated by myeloperoxidase and is linked to a non-Fenton oxidative event marked by POBN⋅.

Adriamycin transport and sensitivity in fatty acid-modified leukemia cells

The membrane phospholipids of L1210 murine leukemia cells were modified by supplementing the growth medium with micromolar concentrations of polyunsaturated or monounsaturated fatty acids. This procedure results in enrichment of cellular phospholipids by the supplemented fatty acid. Enrichment with polyunsaturated fatty acids resulted in a marked increase in sensitivity to adriamycin as compared to enrichment with monounsaturated fatty acids. The increased cytotoxicity was directly proportional to the extent of unsaturation of the inserted fatty acid, but there was no difference in cells enriched with n-3 compared with n-6 family fatty acids. To explore the mechanism of this observation, we examined whether augmented uptake of the drug might explain the increased cytotoxicity. The uptake of [14C]adriamycin, which was approximately linear at later time points, was only partially temperature dependent and never reached a steady state. Initial uptake at time points prior to 60 s could not be measured due to high and variable rapid membrane adsorption. Cellular accumulation of drug was greater in the docosahexaenoate 22:6-enriched L1210 cells as compared to oleate 18:1-enriched cells and was about 32% greater after 20 min. When L1210 cells were enriched with six fatty acids of variable degrees of unsaturation, the accumulation of adriamycin was directly correlated with the average number of double bonds in the fatty acids contained in cellular phospholipids. There was no difference in efflux of drug from cells pre-loaded with adriamycin. We conclude that the greater accumulation of adriamycin by the polyunsaturated fatty acid-enriched L1210 cells likely explains the increased sensitivity of these cells to adriamycin compared to 18:1-enriched cells.

Membrane fatty acid modification in tumor cells: A potential therapeutic adjunct

The fatty acid compositions of several tumors have been modified sufficiently to alter some of their properties and functions. These modifications were produced in culture by adding specific fatty acids to the growth medium or by feeding fat-supplemented diets to tumor-bearing mice. The phospholipid fatty acid composition of the plasma membrane was modified, but there were no changes in membrane phospholipid or cholesterol content or in phospholipid head group composition. Each of the most abundant membrane phosphoglyceride fractions exhibited some degree of fatty acid modification. Electron spin resonance measurements with nitroxystearate spin probes indicated that the fatty acid modifications were sufficient to alter the physical properties of the plasma membrane. The Km′ for methotrexate uptake was reduced when the L1210 leukemia cells were enriched in linoleic acid. Even when the kinetics of uptake at 37 C were not altered, such as for melphalan and phenylalanine uptake, the temperature transition of transport was modified, indicating that these transport systems also are responsive to the membrane fatty acid modifications. Enrichment with highly polyunsaturated fatty acid did not affect either the growth rate or radiosensitivity of the L1210 leukemia. However, the sensitivity of the L1210 cells to the cytotoxic effects of Adriamycin and hyperthermia was increased. These findings suggest the possibility that fatty acid modification of tumors may be a useful adjunct to certain currently available therapeutic modalities.

Membrane lipid alteration: effect on cellular uptake of mitoxantrone.

We have studied the effect of membrane structural alteration on the cellular association of the anticancer drug mitoxantrone whose uptake is not carrier-mediated. Membrane fatty acids of L1210 cells were modified by incubating the cells with the highly unsaturated docosahexaenoic acid (22∶6), which results in isolated plasma membranes with 37% of the fatty acids as 22∶6, or with the monounsaturated oleic acid (18∶1), which results in 58% of the fatty acids as 18∶1. The rate of uptake by 22∶6-enriched cells during the first min was 62% greater than by those enriched with 18∶1. The higher rate was recorded at 0.5–16 μM, pH 6.6–7.6 and temperatures 10–40 C. The difference in cell-associated drug apparently was not due simply to a change in mitoxantrone solubility as measured by partitioning of the drug in lipophilic-hydrophilic systems containing lipids from the fatty-acid altered cells. We conclude that the type of fatty acids contained in L1210 cell membranes can affect the cell association of mitoxantrone. This effect could be on transmembrane flux or be due to differences in binding of the drug to intracellular structures.

Decreased cisplatin uptake by resistant L1210 leukemia cells

Cisplatin resistance remains poorly understood compared to other forms of anti-neoplastic drug resistance. In this report radiolabeled cisplatin and rapid separation techniques were used to compare drug uptake by L1210 leukemia cells that are sensitive (K25) or resistant (ZCR9) to cisplatin. Uptake of cisplatin by both cell lines was linear without saturation kinetics up to 100 microM. The resistant ZCR9 cells had 36-60% reduced drug uptake as compared to its sensitive parent line, K25. In contrast, there was no difference in the rate of efflux. We conclude that a decreased rate of uptake is one possible mechanism of cellular cisplatin resistance.

Analysis of the presenting features of adult acute leukemia: The French‐American‐British classification

The authors have performed a clinical and statistical analysis of the presenting features of adult acute leukemia classified according to the French‐American‐British (FAB) hematopathologic criteria. Observations were made on 70 variables of history, physical examination, and laboratory examination recorded for 195 patients seen during a recent six year interval. The incidence of each category as determined by consensus of three observers was L1, 9%; L2, 17%; L3, 3%; M1, 21%; M2, 22%; M3, 5%; M4, 21%; M5, 4%; and M6 1%. There were recurring features of each FAB category and for aggregated categories (myeloid, lymphoid). Some groups such as L1, M3, M4, and M5 were characterized by many distinctive characteristics. In contrast, the L2, M1, and M2 categories had few distinctive characteristics, although L2 shared many features with the other lymphoid groups. The distinctness of the categories was quantitated by stepwise discriminant analysis. Using only a few computer‐selected clinical variables, the authors classified patients into the correct FAB category with an accuracy of over 65% for some groups. The accuracy in discriminating between lymphoid and myeloid groups, the important therapeutic distinction, was 82%. This study demonstrates that many of the categories defined by the FAB criteria have characteristic clinical features at presentation.

Hypoplastic acute leukemia

There have been few reports of acute leukemia presenting with a hypocellular bone marrow. All patients diagnosed as having acute leukemia were identified during a recent six‐year interval who had blast cells plus promyelocytes of >30% and marrow cellularity of needle biopsy ≤ 50%. Of 195 patients analyzed, 15 (7.7%) fulfilled the criteria. Ten patients were men and five women; the median age was 68 years with a range of 4–82. Seven complained of fatigue of 6–12 months duration, five were seen with occult infection, and three were asymptomatic. Hepatosplenomegaly was absent in 93% and none had lymphadenopathy. Fourteen patients were pancytopenic with median leukocyte count at presentation of 1.5 × 109/liter, hemoglobin of 9.0 g/dl, and platelet count of 55 × 109/liter. Circulating blast cells were not observed in ten patients; in the other five they were <0.7 × 109/liter. The morphology of all cases appeared myeioid and Auer rods were seen in three patients; however, in one the peroxidase was negative. Classification according to FA criteria revealed ten to be M1, three to be M2, one M4, and one L2. Median survival of the entire group was seven months. Of seven patients receiving no chemotherapy, two survived longer than 1 year (14, 24.5 months), one is alive at 7+ months, and the median survival was seven months. Eight patients with life‐threatening complications received various combination regimens including an anthracycline, cytosine arabinoside, 6‐thioguanine, vincristine, and prednisone. Five died of treatment complications; two achieved durable complete remission and are free of disease at 17 and 27 months. It can be concluded that hypoplastic acute leukemia is a distinct nosologic entity affecting primarily older patients with myeloid leukemia. Remission induction therapy in patients who are seriously ill has a low success rate, and in some patients prolonged survival is possible with supportive care alone.

Liver disease complicating the management of acute leukemia during remission

Eight adults who developed persisting liver function abnormalities during remission from acute leukemia (6 acute nonlymphoblatic leukemia and 2 acute lymphoblastic leukemia) are reported. These patients constituted 20% of the adults with acute leukemia attaining remission over the time period studied. Although we were unable to be absolutely certain of the etiology of the liver dysfunction, the following findings characterize the problem: 1) onset following red blood cell and platelet transfusions in all cases; 2) minimal symptoms and signs except for transient episodes of jaundice; 3) fluctuating, but often marked, increases in liver transaminases; 4) no other consistent laboratory abnormalities; 5) liver biopsies showing varying degrees of inflammation; 6) a consistent decrease in transaminase levels following pulse chemotherapy; 7) absence of progression of abnormalities during the observation period. This group of patients did not have a worse prognosis than patients with normal liver function. We feel that it is important to recognize this entity and to not withhold antileukemic therapy.