A phase II trial of imatinib mesylate in Merkel cell carcinoma (neuroendocrine carcinoma of the skin): A Southwest Oncology Group Study (S0331)

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Background: Merkel cell carcinoma (MCC, neuroendocrine carcinoma of the skin) frequently stains strongly for c-KIT (CD-117) expression. We therefore evaluated imatinib mesylate as a treatment for MCC. Methods: Eligibility included patients with measurable metastatic or unresectable MCC with CD117 expression by immunostaining. A Zubrod performance status of 0–2, adequate hematologic, renal, and hepatic function was also required. Imatinib 400 mg daily was administered orally in 28-day cycles. Results: A total of 25 patients were accrued to this trial from 13 institutions, with 6 accrued through Intergroup participation by the Eastern Cooperative Oncology Group. Two patients were ineligible (one was found not to express CD117 on central pathology review, and one lacked measurable disease). These 23 patients were included in the analysis. Imatinib was well tolerated with Grade 1 or 2 nausea, diarrhea, and hematologic toxicity as the most frequent side effects. There were no complete responses (0%) and 1 confirmed partial response (4%) in the 23 evaluable patients (4% objective response rate, CI 0 -22%). In addition, stable disease was observed in 3 patients (9, 4 and 3 months). Median progression-free survival was 1 month (95% CI: 1–2 months). Estimated 6 month PFS was 4%. Median overall survival was 5 months (95% CI 2–8 months). The estimated one-year overall survival was 17% (95% CI: 0% - 33%). There were three on-study deaths. All were attributed to tumor progression. One patient achieved a partial response and another had prolonged disease stabilization while receiving treatment. DNA sequencing of c-KIT was performed on tumor tissue from on a non- responding patient and the one patient with long-term stable disease (9 months). Neither demonstrated an activating mutation in c-KIT. Unfortunately, the patient with partial response withdrew consent for the study and DNA sequencing could not be performed. Conclusions: The majority of patients progressed rapidly within 1–2 cycles of treatment. The observed progression-free survival and overall survival were not adequate to conclude that this agent was active in advanced MCC. The planned second stage of patient accrual was not opened.

No significant financial relationships to disclose.

Evaluation of gemcitabine in patients with recurrent or metastatic squamous cell carcinoma of the head and neck: a Southwest Oncology Group phase II study

A phase II trial of gemcitabine (Gemzar), a nucleoside analogue with broad activity in solid tumors, was performed in patients with recurrent or metastatic squamous cell carcinoma of the head and neck. A total of 26 eligible patients were registered to receive a dose of 1250 mg/m2 weekly for 3 weeks, followed by a 1 week rest. Toxicity was evaluable in 26 patients. Nausea and vomiting occured in 11 and 6 patients, repectively. Grade 3 or 4 hematologic toxicities were infrequent. Two patients developed neutropenic infections. One patient developed fatal liver failure which was thought due to progressive liver metastases or infection 14 days after a single dose of gemcitabine. There were no objective treatment responses (95% CI 0-13%), with a median survival of 6 months in this highly resistant disease population. Gemcitabine is not considered active enough as monotherapy for further evaluation in this disease population.

Evaluation of Tomudex in patients with recurrent or metastatic squamous cell carcinoma of the head and neck: a Southwest Oncology Group study

A phase II trial of Tomudex (raltitrexed, ZD 1694), a new thymidylate synthase inhibitor, was performed in patients with recurrent or metastatic squamous cell carcinoma of the head and neck. This trial demonstrated that Tomudex was well tolerated in this patient population. Nausea and vomiting were minimal, and hematologic toxicities were relatively infrequent. Only one patient was withdrawn from the study due to toxicity (grade 4 diarrhea). One patient exsanguinated from a rent in the carotid artery in an area of tumor involvement, and was categorized as a grade 5 toxicity. Thus 25/27 patients were able to complete at least 2 cycles of treatment. Tomudex demonstrated a 3.7% response rate (95% CI 0.1-19%), with a median survival of 6 months in this highly resistant disease population. Tomudex is not considered active enough as monotherapy for further evaluation in this disease population.

Cytokines secreted by lymphokine-activated killer cells induce endogenous nitric oxide synthesis and apoptosis in DLD-1 colon cancer cells

IL-2-activated killer lymphocytes (LAK cells) secrete inflammatory cytokines such as interferon-gamma (IFN-gamma) and tumor necrosis factor alpha (TNFalpha) that can induce nitric oxide (NO) synthesis. We evaluated whether LAK cells could activate NO synthesis in human cancer cells. LAK cells and their culture supernatants induced NO synthesis in DLD-1 colon cancer cells in a dose-dependent manner. NO synthesis was inhibited completely by blocking antibodies to IFN-gamma, demonstrating a key role for this LAK cell cytokine in regulating NO synthesis. The addition of TNFalpha antibodies resulted in partial inhibition. Induction of iNOS mRNA and protein expression in DLD-1 cells was detected. Endogenous NO production inhibited DLD-1 cell proliferation and induced apoptosis, processes that were inhibitable by the NO synthase inhibitor N(G)-monomethyl-l-arginine. Our study has identified a novel, non-contact-dependent LAK cell cytotoxic mechanism: induction of growth inhibition and programmed cell death due to endogenous NO synthesis in susceptible human cancer cells.

Soluble biodegradable polymer-based cytokine gene delivery for cancer treatment

Transgene expression and tumor regression after direct injection of plasmid DNA encoding cytokine genes, such as mIL-12 and mIFN-gamma, remain very low. The objective of this study is to develop nontoxic biodegradable polymer-based cytokine gene delivery systems, which should enhance mIL-12 expression, increasing the likelihood of complete tumor elimination. We synthesized poly[alpha-(4-aminobutyl)-l-glycolic acid] (PAGA), a biodegradable nontoxic polymer, by melting condensation. Plasmids used in this study encoded luciferase (pLuc) and murine interleukin-12 (pmIL-12) genes. PAGA/plasmid complexes were prepared at different (+/-) charge ratios and characterized in terms of particle size, zeta potential, osmolality, surface morphology, and cytotoxicity. Polyplexes prepared by complexing PAGA with pmIL-12 as well as pLuc were used for transfection into cultured CT-26 colon adenocarcinoma cells as well as into CT-26 tumor-bearing BALB/c mice. The in vitro and in vivo transfection efficiency was determined by luciferase assay (for pLuc), enzyme-linked immunosorbent assay (for mIL-12, p70, and p40), and reverse transcriptase-polymerase chain reaction (RT-PCR) (for Luc and mIL-12 p35). PAGA condensed and protected plasmids from nuclease degradation. The mean particle size and zeta potential of the polyplexes prepared in 5% (w/v) glucose at 3:1 (+/-) charge ratio were approximately 100 nm and 20 mV, respectively. The surface characterization of polyplexes as determined by atomic force microscopy showed complete condensation of DNA with an ellipsoidal structure in Z direction. The levels of mIL-12 p40, mIL-12 p70, and mIFN-gamma were significantly higher for PAGA/pmIL-12 complexes compared to that of naked pmIL-12. This is in good agreement with RT-PCR data, which showed significant levels of mIL-12 p35 expression. The PAGA/pmIL-12 complexes did not induce any cytotoxicity in CT-26 cells as evidenced by 3-¿4, 5-dimethylthiazol-2-yl¿-2,5-diphenyltetrazolium bromide assay and showed enhanced antitumor activity in vivo compared to naked pmIL-12. PAGA/pmIL-12 complexes are nontoxic and significantly enhance mIL-12 expression at mRNA and protein levels both in vitro and in vivo.

Immunosuppressive effects of factor IX products: an in vitro study

The effects of a recombinant factor IX product (BeneFix), and of five plasma-derived factor IX products, AlphaNine, Immunine, Konyne, Mononine and Replinine on in vitro peripheral blood mononuclear cell (PBMC) immune function were compared in a blinded study. We assessed the effects of these products on Con-A-induced lymphocyte proliferation and interleukin-2 and interleukin-10 secretion, expression of lymphocyte activation markers, and nitric oxide secretion by stimulated mouse peritoneal macrophages. At 1 mL-1 for 48 h, Konyne reduced Con-A-induced mitogenesis by 50% (P < 0.05); AlphaNine, Mononine and BeneFix had no effect. At 10 IU mL-1, Con-A-induced mi- togenesis was at control levels with Mononine and BeneFix, but was reduced to <15% (P < 0.05) with each of the other products. IL-2 and IL-10 secretion by Con-A-stimulated lymphocytes was also markedly depressed by all the products tested except Mononine and BeneFix. Dialysis of these products did not substantially affect these results. Flow cytometric analysis of lymphocyte activation markers following Con-A stimulation showed that Konyne also decreased IL-2 receptor alpha and beta chain (CD25 and CD122) induction on PBMC. Konyne also inhibited nitric oxide secretion to levels <18% of controls. These results indicate that certain factor IX products, including some of purported higher purity, substantially depress in vitro immune function. The importance of these findings to in vivo immune function in haemophilia B patients remains to be established.

A phase III comparison of high dose ARA-C (HIDAC) versus HIDAC plus mitoxantrone in the treatment of first relapsed or refractory acute myeloid leukemia Southwest Oncology Group Study

The aim of this study is to determine whether the addition of mitoxantrone to high dose cytarabine improves the outcome of treatment in patients with relapsed or refractory acute myeloid leukemia (AML). One hundred and sixty-two eligible patients, 14-76 years of age, with AML either in first relapse or that failed to respond to initial remission induction therapy, with no CNS involvement were randomized to receive therapy with cytarabine 3 gm/M2 i.v. over 2 h every 12 h for 12 doses on days 1-6 (Arm I) (HIDAC); or HIDAC plus mitoxantrone 10 mg/M2 i.v. daily on days 7 9 (Arm II) (HIDAC + M). Patients achieving complete remission were treated with three courses of consolidation including HIDAC (Ara-C 3 gm/M2 i.v. 12 h days 1 3; 2 gm/M2 over age 50) alone (ARM I) or with mitoxantrone (10 mg/M2 i.v. day 1) (ARM II). Among 162 patients (81 HIDAC, 81 HIDAC + M) evaluated for induction toxicity, there were 10 (12%) induction deaths with HIDAC and 13 (17%) with HIDAC + M (2-tailed P = 0.65). Most early deaths were due to infection and/or hemorrhage. Among 162 patients evaluated for responses to induction therapy, 26/81 (32%) HIDAC and 36/81 (44%) HIDAC + M patients achieved complete remission (two-tailed P = 0.15). Although this difference was not statistically significant in univariate analysis, it was after adjusting for the effects of WBC and PMN percentage in multivariate analysis (P=0.013). Median survivals from study entry were 8 months (HIDAC) and 6 months (HIDAC + M); 2-tailed logrank P = 0.58. Among 48 patients registered for consolidation, the median disease-free survivals from that registration were 8 months with HIDAC and 11 months with HIDAC + M (P = 0.60). There were three treatment-related deaths during consolidation (1 HIDAC, 2 HIDAC + M), all due to infections. In this randomized trial, the addition of mitoxantrone to high-dose cytarabine was associated with a trend toward a higher CR rate. There was less evidence for an advantage in disease-free or overall survival, although any such conclusion is limited by the size of the study.

Relative importance of cytotoxic T lymphocytes and nitric oxide-dependent cytotoxicity in contractile dysfunction of rejecting murine cardiac allografts

BACKGROUND

Previous in vitro studies have suggested that both cytotoxic T lymphocyte (CTL)-mediated and non-CTL-mediated myocyte lysis occur during murine cardiac heterotopic allograft rejection, but the relative importance of these injury mechanisms on myocardial function is not established. We therefore compared the in vivo effects of depletion of CTL and inhibition of nitric oxide synthase (NOS) on contractility of the rejecting heart.

METHODS

Syngeneic (BALB/c into BALB/c) and allogeneic (BALB/c into C57/B16) heterotopic abdominal cardiac transplants were performed. In some of the allogeneic transplants, CD8+ lymphocytes were depleted by intraperitoneal injection of anti-CD8 monoclonal antibody. NOS inhibition was accomplished by continuous infusion of NG-monomethyl-L-arginine via a subcutaneous osmotic pump. Five days after transplantation, the abdominal cavity was opened and the transplanted heart exposed. Base to apex developed force was measured during spontaneous beating at a diastolic stretch of 4 g by placing a suture through the apex of the heart and attaching it to a strain gauge. Effects of interventions on graft survival were determined by recording the days required for loss of palpable graft contractions.

RESULTS

Allogeneic hearts showed a significant reduction in systolic force compared to non-rejecting syngeneic hearts. Depletion of CD8+ cells improved contractility significantly relative to non-depleted allogeneic hearts, but contractility remained significantly reduced relative to syngeneic hearts. Developed force in allogeneic hearts was also improved by NOS inhibition (P<0.01), and NG-monomethyl-L-arginine infusion slightly prolonged graft survival.

CONCLUSION

Both CTL-mediated and NOS-dependent (possibly macrophage-mediated) mechanisms contribute to contractile dysfunction during early cardiac allograft rejection in this model. However, NOS inhibition combined with CTL depletion only slightly prolongs graft survival in this model.

Nitric oxide exposure inhibits induction of lymphokine-activated killer cells by inducing precursor apoptosis

Nitric oxide synthesis is strongly induced during IL-2 treatment of mice and humans. While this free radical can act as an antitumor mechanism by inhibiting cellular respiration and DNA synthesis in cancer cells, immunosuppressive effects have also been suggested. We evaluated the effects of NO exposure on the induction of murine lymphokine-activated killer (LAK) cells from splenocytes by IL-2 (6000 IU/ml). When splenocytes were exposed to pure NO gas for 30 min prior to the addition of IL-2, complete abrogation of LAK cell cytotoxicity was observed. In contrast, cytolytic activity of already activated LAK cells was only minimally affected by NO exposure. NO exposure markedly depressed cellular proliferation in response to concanavalin A or IL-2. Immunostaining of LAK cell cultures following NO exposure revealed a marked decrease in CD8+, and peanut lectin (PNA+)/CD56+ subsets (48 and 69%). Dual staining of LAK cells for DNA strand breaks and either PNA or CD8+ identified the induction of programmed cell death in these subsets 12-24 h following NO exposure. These experiments demonstrate that NO has the capacity to inhibit LAK cell induction by inducing apoptosis of cytolytic lymphocyte precursors.

Receptor-mediated activation of murine peritoneal macrophages by antithrombin III acts as a costimulatory signal for nitric oxide synthesis

We evaluated the effect of antithrombin III (ATIII), a serine protease inhibitor (SERPIN), on induction of nitric oxide (NO) synthesis in murine peritoneal macrophages. Incubation of macrophages with ATIII plus interferon-gamma (IFN-gamma) but not ATIII alone induced nitrite accumulation (a metabolite of NO) in a dose-dependent manner. Expression of the inducible nitric oxide synthase isoform was confirmed by Western blot. NO synthesis was inhibited by NG-monomethyl-l-arginine, by complexing ATIII with thrombin or by rabbit anti-human ATIII antiserum. Addition of polymyxin B to macrophage cultures failed to inhibit ATIII/IFN-gamma-induced NO synthesis, excluding lipopolysaccharide contamination. 125I-ATIII bound to macrophages in a dose-dependent, specific, and saturable manner, with a Km of approximately 7.1 nM. Our results demonstrate that ATIII, but not ATIII/thrombin complex, acts to costimulate macrophage activation and NO synthesis via a novel receptor mediated mechanism, which may indicate a role for SERPINs in macrophage activation.

Effects of total parental nutrition (TPN) during high-dose interleukin-2 treatment for metastatic cancer

Patients treated with high doses of interleukin-2 (IL-2) develop profound anorexia, malaise, loss of energy, mucositis, nausea, and vomiting, which may contribute to poor nutrition. We hypothesized that total parenteral nutrition (TPN) administration would ameliorate these changes and could improve fluid and electrolyte balance. A retrospective analysis of protein and energy intake was performed in 21 sequential patients who received a normal diet (controls) and 16 subsequent patients who received TPN during IL-2 treatment. The effect of TPN on laboratory abnormalities induced by IL-2 was also evaluated. Within 24 h of starting IL-2, mean energy intake declined to 2.5-2.8 kcal/kg in controls in contrast to the energy intake of 25-29 kcal/kg in patients receiving TPN. Protein nutrition was affected in a similar fashion, with a markedly lower protein intake in controls (0.08-0.12 g/kg) than in the TPN group (1.02-1.10 g/kg). TPN improved serum calcium and potassium concentrations, particularly during spontaneous diuresis after completion of IL-2 treatment. Unexpectedly, TPN decreased the frequency and severity of cholestatic jaundice caused by IL-2. Patients receiving TPN had an increased propensity for hyperglycemia and hypophosphatemia. High-dose intravenous bolus IL-2 therapy resulted in a markedly negative nutritional balance in control patients. A brief period of TPN during IL-2 treatment was well tolerated and corrected calorie and protein malnutrition. TPN administration also improved control of serum electrolytes. TPN did not adversely affect tumor progression or patient survival.

Acute dyslipoproteinemia induced by interleukin-2: lecithin:cholesteryl acyltransferase, lipoprotein lipase, and hepatic lipase deficiencies

Recombinant human interleukin-2 (rIL-2) is used to treat refractory cancers. During such treatment, patients develop severe hypocholesterolemia along with striking alterations in the concentration and composition of the circulating lipoproteins. The present study was undertaken to gather information about the pathogenesis of these abnormalities. Patients were studied before-, during- and after a 5-day course of high dose i.v. rIL-2. Whole plasma cholesterol was markedly reduced by rIL-2 administration (52%; P < 0.001), whereas the triglyceride concentration did not change. Thus, the lipoproteins became triglyceride enriched (P = 0.004). Low density lipoprotein cholesterol, apolipoprotein B (apoB), high density lipoprotein cholesterol, and apoA-I concentrations all decreased. Esterified cholesterol levels were markedly reduced. Total plasma apoE increased markedly, and two kinds of abnormal particles appeared: 1) beta-migrating, very low density lipoproteins; and 2) discoidal, apoE- and phospholipid-containing particles with abnormal density and electrophoretic mobility. The activities of two lipoprotein triglyceride hydrolases, lipoprotein lipase and hepatic lipase, fell significantly during treatment and returned promptly to pretreatment levels after rIL-2 was discontinued. Lecithin:cholesteryl acyltransferase (LCAT) activity also decreased significantly (64%) during treatment, but in contrast to the lipases, remained low for at least 5 days after the last dose of rIL-2 (P < 0.001). High dose i.v. rIL-2 induces severe dyslipidemia with deficiencies of both postheparin lipases and acute LCAT deficiency. Most, if not all, of the lipoprotein changes observed are explained by the LCAT deficiency that follows IL-2-induced hepatocellular injury and cholestasis.

Nitric oxide synthesis contributes to IL-2-induced antitumor responses against intraperitoneal Meth A tumor

IL-2 therapy is a potent inductive stimulus for nitric oxide (NO.) synthesis in mice and humans. It is not yet clear whether NO. can contribute to IL-2-induced therapeutic responses. The murine skin cancer Meth A is relatively resistant to lymphokine-activated killer (LAK) cell killing, allowing evaluation of the role of IL-2-induced NO. synthesis in vivo, without contribution by LAK cells. Subcutaneous IL-2 treatment of mice bearing i.p. Meth A tumor increased nitrite production by cells derived from ascites (63 +/- 14 microM vs 3.2 +/- 1.5 microM in untreated controls). N omega-monomethyl-L-arginine (MLA), NO. synthase inhibitor, prevented this increase. NO. production correlated in an inverse fashion with tumor cell proliferation in vitro. Evidence for IL-2-induced heme nitrosylation was demonstrated in tumor cells by electron paramagnetic resonance spectroscopy. By immunomagnetic depletion experiments, macrophages were implicated as a major source of NO. synthesis. Cytologic and flow-cytometric evaluation revealed that IL-2 treatment resulted in enhanced lymphocyte and macrophage recruitment into malignant ascites, and decreases in tumor cell recovery. MLA administration further increased host cell recovery. Subcutaneous IL-2 therapy increased urinary nitrate excretion up to eightfold in mice, and appeared to produce a significant survival advantage that was prevented by MLA administration.

Nitric oxide synthesis contributes to IL-2-induced antitumor responses against intraperitoneal Meth A tumor

IL-2 therapy is a potent inductive stimulus for nitric oxide (NO.) synthesis in mice and humans. It is not yet clear whether NO. can contribute to IL-2-induced therapeutic responses. The murine skin cancer Meth A is relatively resistant to lymphokine-activated killer (LAK) cell killing, allowing evaluation of the role of IL-2-induced NO. synthesis in vivo, without contribution by LAK cells. Subcutaneous IL-2 treatment of mice bearing i.p. Meth A tumor increased nitrite production by cells derived from ascites (63 +/- 14 microM vs 3.2 +/- 1.5 microM in untreated controls). N omega-monomethyl-L-arginine (MLA), NO. synthase inhibitor, prevented this increase. NO. production correlated in an inverse fashion with tumor cell proliferation in vitro. Evidence for IL-2-induced heme nitrosylation was demonstrated in tumor cells by electron paramagnetic resonance spectroscopy. By immunomagnetic depletion experiments, macrophages were implicated as a major source of NO. synthesis. Cytologic and flow-cytometric evaluation revealed that IL-2 treatment resulted in enhanced lymphocyte and macrophage recruitment into malignant ascites, and decreases in tumor cell recovery. MLA administration further increased host cell recovery. Subcutaneous IL-2 therapy increased urinary nitrate excretion up to eightfold in mice, and appeared to produce a significant survival advantage that was prevented by MLA administration.

Effectiveness and toxicity of protracted nitric oxide synthesis inhibition during IL-2 treatment of mice

The current study was designed to characterize nitric oxide (NO.) synthesis during interleukin-2 (IL-2) treatment of mice, and to determine whether NO. mediated IL-2-induced "vascular leak." We developed a technique for chronic subcutaneous infusion of the NO. synthase inhibitor N omega monomethyl-L-arginine (MLA) via osmotic minipump to aid in further study of these processes. After IL-2 administration to C3H/HeN mice (180,000 IU i.p. b.i.d. for 5 days), NO. synthesis increased two-to-three fold, peaking on days 5-8. Administration of MLA reduced NO. synthesis in both IL-2-treated mice (from 2.7 to 1 microM/mouse/day), and normal mice (from 1 to 0.5 microM/mouse/day). This agent decreased IL-2-induced radiolabeled albumin accumulation in the liver after i.p. IL-2 administration (p < 0.02). MLA infusions resulted in minimal systemic toxicity in mice, as reflected by complete blood counts or serum chemistries. MLA also did not impair lymphokine-activated killer cell induction in vitro or in vivo, or alter IL-2-induced tumor responses in a 3-day pulmonary metastasis model. These experiments demonstrated that NO. is a mediator involved in the genesis of vascular permeability induced by IL-2 treatment. Studies designed to further evaluate the toxicity and usefulness of MLA infusions to modify this IL-2 induced toxicity appear to be warranted.

Use of N-acetyl cysteine to increase intracellular glutathione during the induction of antitumor responses by IL-2

IL-2 therapy can induce marked oxidative stress via reactive oxygen and nitrogen intermediates. Glutathione, the major intracellular reductant, may become rate limiting to cytotoxic lymphocyte activation and proliferation under these circumstances. N-Acetyl cysteine (NAc-cys) was used to increase intracellular glutathione levels during lymphokine-activated killer (LAK) cell activation by IL-2. Incubation of splenocytes with NAc-cys (0.6 to 1.0 mM) resulted in significant changes in intracellular reduced and total glutathione (92% and 58% increase, respectively) at 96 h. These levels correlated with markedly enhanced cell proliferation (threefold) and cytolytic effector cell generation (&gt; fivefold increase in LU/10(6) cells) induced by the combination of NAc-cys with IL-2. IL-2 exposure by itself unexpectedly increased intracellular reduced glutathione by 43%. IL-2 and NAc-cys were synergistic in increasing glutathione levels (reduced glutathione: 292% increase; total: 251% increase). Inhibition of glutathione synthesis, using L-buthionine-(S,R)-sulfoximine reversed the effects of NAc-cys on intracellular glutathione, as well as cellular proliferation and cytotoxicity. This experiment established that the effects of NAc-cys required de novo glutathione synthesis. In conjunction with IL-2/LAK treatment, oral NAc-cys administration (260 to 900 mg/kg/day for 7 days) significantly decreased tumor progression in a refractory s.c. tumor model. A small fraction of mice (11 to 17%) had complete tumor regressions. NAc-cys may be useful as an adjunct to increase the antitumor activity of IL-2/LAK therapy.

Use of N-acetyl cysteine to increase intracellular glutathione during the induction of antitumor responses by IL-2

IL-2 therapy can induce marked oxidative stress via reactive oxygen and nitrogen intermediates. Glutathione, the major intracellular reductant, may become rate limiting to cytotoxic lymphocyte activation and proliferation under these circumstances. N-Acetyl cysteine (NAc-cys) was used to increase intracellular glutathione levels during lymphokine-activated killer (LAK) cell activation by IL-2. Incubation of splenocytes with NAc-cys (0.6 to 1.0 mM) resulted in significant changes in intracellular reduced and total glutathione (92% and 58% increase, respectively) at 96 h. These levels correlated with markedly enhanced cell proliferation (threefold) and cytolytic effector cell generation (> fivefold increase in LU/10(6) cells) induced by the combination of NAc-cys with IL-2. IL-2 exposure by itself unexpectedly increased intracellular reduced glutathione by 43%. IL-2 and NAc-cys were synergistic in increasing glutathione levels (reduced glutathione: 292% increase; total: 251% increase). Inhibition of glutathione synthesis, using L-buthionine-(S,R)-sulfoximine reversed the effects of NAc-cys on intracellular glutathione, as well as cellular proliferation and cytotoxicity. This experiment established that the effects of NAc-cys required de novo glutathione synthesis. In conjunction with IL-2/LAK treatment, oral NAc-cys administration (260 to 900 mg/kg/day for 7 days) significantly decreased tumor progression in a refractory s.c. tumor model. A small fraction of mice (11 to 17%) had complete tumor regressions. NAc-cys may be useful as an adjunct to increase the antitumor activity of IL-2/LAK therapy.

Induction of iron-derived EPR signals in murine cancers by nitric oxide. Evidence for multiple intracellular targets

The cell-mediated immune response to syngeneic tumors activates the cytokine-inducible nitric oxide synthase. We observed that syngeneic murine tumors exhibited EPR signals related to iron-nitrosyl complex formation. Three different EPR active iron-nitrosyl species were observed, an Fe(RS)2(NO)2 signal and two differentiable heme-nitrosyl complexes. Hemoglobin assays showed that the heme-nitrosyl signals were not derived from contaminating hemoglobin. Signal amplitudes were attenuated in mice treated with N omega-mono-methyl-L-arginine (MLA), an inhibitor of nitric oxide synthase. Tumors grown in vivo contained EPR signals while those grown in culture without continuing cytokine stimulation lost the signals after a few days. Cultured cells that were treated with cytokines, or that were cocultivated with cytokine-activated macrophages, regained EPR active complexes. These results show that the cell-mediated immune response to syngeneic tumors involves the induction of nitric oxide synthase. While nitric oxide synthesis is induced in both tumor infiltrating macrophages and in the tumor cells themselves, only tumor cells contributed to formation of heme-nitrosyl complexes. This result indicates the presence of a novel intracellular target for NO within tumor cells.

Macrophage nitric oxide synthesis delays progression of ultraviolet light-induced murine skin cancers

The role of macrophages in the host immune response against cancers remains uncertain. Since nitric oxide synthesis represents a significant macrophage antitumor mechanism in vitro, we evaluated whether NO was synthesized during the immune response to growing murine skin cancers. NO synthesis was readily detectable in enzymatically dissociated tumors (RD-995 and LR-298) and was inhibited by N omega-monomethyl-L-arginine (MLA) and by macrophage depletion. Nitrosylation of iron-sulfur and heme complexes was observed in these tumors using electron paramagnetic resonance spectroscopy. NO production in the presence of increasing concentrations of MLA correlated inversely with tumor cell proliferation in vitro. To elucidate the role of NO during in vivo tumor progression, tumor-bearing mice were treated with continuous infusions of the nitric oxide synthase inhibitor MLA. MLA-treated mice demonstrated increased growth and delayed rejection of the highly antigenic UV radiation-induced regressor tumor LR-298. These experiments demonstrate that macrophage-derived NO synthesis can contribute to the antitumor immune response in vivo.

Intrathecal administration of interleukin-2 for meningeal carcinomatosis due to malignant melanoma: sequential evaluation of intracranial pressure, cerebrospinal fluid cytology, and cytokine induction

A patient with interleukin (IL)-2 responsive metastatic melanoma developed meningeal carcinomatosis. Treatment was attempted with intrathecal (i.t.) IL-2 (5 weekly doses of 3-6 x 10(6) IU) without glucocorticosteroids. Marked increases in cerebrospinal fluid (CSF) pressure occurred 5-10 h following each IL-2 dose, resulting in reversible abnormalities of neurologic function. IL-2 clearance from the CSF ranged from 21 to 85 ml/h, with an apparent first order rate constant of 0.08-0.23 hr-1. These values were consistent with clearance by bulk flow mechanisms. Clearance also correlated directly with peak CSF pressure. Progressive increases in CSF tumor necrosis factor (TNF)-alpha and IL-6 levels, but not Il-1 alpha, were also noted over successive treatment cycles. Increasing neutrophilia (peaking at 12 h postdose) and a delayed lymphocytosis and monocytosis (at 20-30 h) were observed with each successive i.t. IL-2 dose. Activated lymphocytes were not observed in the CSF, however, suggesting that an exogenous source of activated lymphokine-activated killer (LAK) cells may be helpful in obtaining effective antitumor responses.

Direct and indirect effects of murine interleukin-2, gamma interferon, and tumor necrosis factor on testosterone synthesis in mouse Leydig cells

It was recently observed that treatment of patients with a high dosage of human interleukin (IL-2) resulted in suppression of plasma concentrations of testosterone. A murine model was developed to assess the direct and indirect effects of murine IL-2 and the secondarily released cytokines, gamma interferon (INF gamma), and tumor necrosis factor (TNF alpha), on testosterone production in isolated Leydig cells. Pretreatment for 24 hours with IL-2 (100 to 500 IU/ml) or INF gamma (100 to 1000 IU/ml) significantly decreased testosterone production in response to luteinizing hormone (LH; P < 0.02 and 0.005, respectively). The combinations of INF gamma with either TNF alpha or IL-2 produced enhanced suppressive effects on Leydig cell testosterone production. Steroidogenic precursors (22-hydroxycholesterol, 17 alpha-hydroxypregnenolone, and dehydroepiandrosterone) restored testosterone secretion to control levels after preincubation with INF gamma or TNF alpha. In contrast, the inhibition of testosterone synthesis produced by either IL-2 or INF gamma plus TNF alpha could be reversed by 17 alpha-hydroxypregnenolone and dehydroepiandrosterone, but not by 22-hydroxycholesterol (P < 0.01). Dibutyryl cyclic adenosine monophosphate was also ineffective in reversing the inhibitory effects of these cytokines on synthesis. Although IL-2 directly inhibited synthesis in isolated Leydig cells, it stimulated testosterone production (P < 0.005) in minced murine testes. This suggests that IL-2 releases regulatory factors from other cells that were able to overcome the direct inhibitory effect of IL-2. This stimulatory effect was not caused by INF gamma and TNF alpha because INF gamma alone or with TNF alpha inhibited (P < 0.005) testosterone production in minced testes.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypoprothrombinemia associated with interleukin-2 therapy: correction with vitamin K

We noted that patients treated with high-dose interleukin (IL)-2 (600,000 IU/kg every 8 h by intravenous bolus) at our institution frequently developed prolongation of their prothrombin time (PT). We therefore performed a prospective study of coagulation function during IL-2 treatment. Since IL-2 treated individuals are known to develop cholestatic liver dysfunction, we hypothesized that the hypoprothrombinemia was due to deficiency of liver-synthesized clotting factors and could be prevented by vitamin K replacement. Alternating patients served as controls or received prophylactic subcutaneous subcutaneous vitamin K. While the nine control patients did not exhibit a significant increase (mean +/- SD) in PT (13.6 +/- 0.6 s pretreatment, 15.0 +/- 2.2 on day 4, and 15.0 +/- 2.5 on day 7, p = 0.77 by repeated measures analysis), three patients developed marked increases in PT (greater than 18 s). Changes in partial thromboplastin time (PTT) over this interval were also not statistically significant. Factor VII levels decreased in all patients from 106 +/- 22 to 59 +/- 16 and 52 +/- 26% on days 4 and 7 (p = 0.0002). Factor VII levels in four patients dropped below the lower limit of normal. Prophylactic treatment of seven patients with vitamin K on days 1-8 of the IL-2 therapy protocol resulted in diminished changes in PT and factor VII compared to control patients (p = 0.02 and 0.003 respectively). No vitamin K-treated patient developed PT or Factor VII levels significantly outside the normal range. Prophylactic vitamin K can prevent hypoprothrombinemia in patients treated with IL-2. This may be of importance in patients with decreased hepatic vitamin K stores, who may be at risk for bleeding complications.

Effects of supravital fluorochromes used to analyze the in vivo homing of murine lymphocytes on cellular function

A number of supravital fluorochromes are available to study lymphocyte homing in vivo. These include fluorescein isothiocyanate (FITC), which binds to cell surface proteins; Hoechst 33342, which binds to AT rich regions of cellular DNA; and the lipid bilayer incorporated dyes PKH-2 and PKH-26. The relative advantages and disadvantages of each of these probes for analyzing murine lymphocyte homing are as yet poorly understood. We evaluated the effects of each dye on labeling efficiency, as well as cell viability, homing, mitogen responsiveness and cytotoxicity. PKH-26 provided long-term labeling (up to 15 days) with the least detrimental effects on cellular function. Detection of FITC in vivo was impaired by tissue autofluorescence, and the dye acted as a co-mitogen for lectin or IL-2-induced proliferation. Hoechst 33342 eluted from cells over a few hours and inhibited lymphocyte proliferation. PKH-2 had detrimental effects on cell viability and resulted in the down-modulation of peripheral lymph node homing receptor expression. None of the probes interfered with the induction of cytotoxic lymphocytes by IL-2. While these fluorochromes are easy to use and provide powerful tools to analyze the lymphocyte localization in vivo, our experiments demonstrate that important limitations are imposed by each probe that need to be considered by investigators during the design and interpretation of experiments.

Reduction of testosterone synthesis after high dose interleukin-2 therapy of metastatic cancer

We have investigated the effect of high dose iv bolus interleukin-2 (IL-2) therapy on sex hormone and adrenal steroid concentrations in six men treated for metastatic renal cell carcinoma or malignant melanoma. Blood concentrations of testosterone, 17 beta-estradiol, LH, FSH, cortisol, dehydroepiandrosterone (DHEA), and DHEA sulfate (DHEA-S) were measured before and after a 5-day course of IL-2 therapy. Cortisol levels rose and DHEA-S decreased insignificantly. DHEA declined, reaching a nadir (P less than 0.001) on day 6, and testosterone decreased significantly on day 2 and reached a nadir on day 6 (P less than 0.0001). Concentrations of both steroids then gradually rose. Estradiol rose on day 4 (P less than 0.001) and then declined. Neither LH nor FSH was affected significantly, although there was a rise in the mean level of LH after IL-2 therapy. Our results suggest that high dose IL-2 therapy in men affects both adrenal and testicular androgen production without inhibiting pituitary trophic hormone secretion. These effects of IL-2 on plasma sex steroids may be the result of cytokines stimulated by IL-2 therapy, rather than direct responses to IL-2.

Cardiomyopathy associated with high-dose interleukin-2 therapy

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Mechanisms of pertussis toxin inhibition of lymphocyte-HEV interactions. I. Analysis of lymphocyte homing receptor-mediated binding mechanisms

The molecular mechanisms by which pertussis toxin (PTX) inhibits lymphocyte homing to peripheral lymph nodes (PLN) remain poorly understood. PTX-treated lymphocytes express homing receptors, yet cannot extravasate into PLN in vivo. Methylation of PTX, a procedure known to inactivate the B-oligomer of the toxin, restored high endothelial venule (HEV) binding capacity. In vitro studies established that toxin exposure inhibited the accessory role of LFA-1 in HEV binding. In contrast, PTX-exposed lymphocytes exhibited normal MEL-14-mediated HEV binding. Analysis of membrane fluidity revealed a 20% decrease in fluorescence polarization in PTX-exposed lymphocytes. On the basis of the current experiments, we propose a "zipper" model of lymphocyte-HEV interaction, in which lateral mobility of adhesion receptors in the cell membrane toward a site of endothelial contact is necessary to maintain adhesion against the shear force due to blood flow. PTX inhibits these processes by decreasing membrane fluidity, and by altering accessory adhesion molecule function.

Human tumor cell line resistance to chemotherapeutic agents does not predict resistance to natural killer or lymphokine-activated killer cell-mediated cytolysis

Cancer cells selected for resistance to natural product chemotherapeutic agents typically display cross-resistance to a variety of structurally and mechanistically diverse agents, a phenomenon known as multidrug resistance. Preliminary studies involving cells selected for multidrug resistance in vitro have suggested that the development of resistance to these agents might simultaneously confer resistance to some forms of immunotherapy. Using human tumor cell line models, we have investigated the relationship between either intrinsic or selected multidrug resistance and sensitivity to natural killer (NK) or lymphokine-activated killer (LAK) cell-mediated cytolysis. We compared the NK and LAK cell susceptibility of three human tumor cell lines displaying distinct mechanisms of selected drug resistance with that of the parental drug-sensitive lines. We also evaluated the NK and LAK susceptibility of five established renal cell carcinoma lines, all of which were found to be intrinsically resistant to doxorubicin and vinblastine. The drug-resistant cell lines were variably sensitive to NK-mediated lysis. In contrast, all drug-resistant cell lines tested were LAK cell sensitive. The NK and LAK cell-mediated cytolytic sensitivities of the drug-resistant cell lines correlated well with those of the drug-sensitive parental lines, suggesting that susceptibility to lysis was related intrinsically to each tumor type, and not to the resistance phenotype. We attempted to correlated the NK sensitivity of these cells with the cell surface expression of Class I or II histocompatibility antigens, or the presence or absence of the membrane inhibitor of complement-mediated reactive lysis. None of these phenotypic markers were found to predict NK resistance. We therefore conclude that these cells, which are either spontaneously resistant to commonly utilized antitumor agents or are multidrug resistant as a result of drug exposure in vitro, remain sensitive to LAK cell-mediated cytolysis. Our studies suggest that interleukin 2-induced LAK cells may be useful in the therapy of some chemotherapy-resistant cancers.

Vascular leak syndrome associated with interleukin-2: chest radiographic manifestations

Adoptive immunotherapy with interleukin-2 (IL-2) is associated with a generalized vascular leak syndrome. Pulmonary edema is a common occurrence and is rarely responsible for acute respiratory failure requiring assisted ventilation. The authors have performed a retrospective review of chest radiographs in 19 patients undergoing the priming course of high-dose IL-2 therapy for metastatic melanoma and renal cell carcinoma. This study was primarily designed to evaluate the prevalence and patterns of pulmonary edema and pleural effusions. During the first 5 days of therapy, alveolar edema was identified in 21% (n = 4) and signs of interstitial edema in 53% (n = 10) of patients. Pleural effusions were seen in 42% (n = 8). No patient in this series required assisted ventilation during this period. However, two patients subsequently developed fatal, drug-related myocardial injury. IL-2 toxicity is a well established cause of self-limited, increased-permeability pulmonary edema.

Phase II evaluation of mitoxantrone in advanced pancreatic carcinoma: a Southwest Oncology Group study

Patient with advanced adenocarcinoma of the pancreas and no prior chemotherapy were treated on a Phase II trial of mitoxantrone. Doses were adjusted for hepatic dysfunction as defined by bilirubin. Twenty-four patients with a bilirubin less than or equal to 1.5 mg% received mitoxantrone 12 mg/m2 i.v. repeated every three weeks. Myelosuppression in the form of leukopenia was the major toxicity. There were no responses in twenty-four evaluable patients.

Changes in homing receptor expression on murine lymphokine-activated killer cells during IL-2 exposure

The effects of IL-2 on the expression of homing receptors by lymphocytes of NK or lymphokine activated killer (LAK) cell derivation has not yet been evaluated. We developed a murine model to evaluate the potential of LAK cells to localize into peripheral lymph nodes since LAK cells are used to treat human cancers which have metastasized to these tissues. Using a frozen section binding assay, LAK cell adhesion to the lymph node microvasculature was easily demonstrable. Inhibition studies demonstrated that LAK cell binding to lymph nodes was mediated by mechanisms previously described in T cells. LAK cell surface expression of the 85- to 95-kDa homing receptor recognized by the antibody MEL-14 on LAK cells was assessed by indirect immunofluorescence. The percentage of cells which bound MEL-14 decreased slightly over 3 days of IL-2 exposure (from 73 to 60%), particularly in the large granular lymphocyte (cytotoxic effector) subpopulation (45% MEL-14+). The expression of another homing-related molecule, leukocyte function-associated Ag-1, markedly increased during activation of LAK cells. Despite the expression of these homing receptors, we observed almost no LAK cell localization into lymph nodes in vivo. Furthermore, IL-2 pretreatment of recipient animals did not increase the adhesion of LAK cells to lymph node microvasculature or enhance their extravasation. IL-2 activation of non-T, non-B lymphocytes results in significant changes in both the expression and function of cell surface homing receptors. Our results indicate that in vitro analysis does not always predict in vivo localization potential.

Changes in homing receptor expression on murine lymphokine-activated killer cells during IL-2 exposure

The effects of IL-2 on the expression of homing receptors by lymphocytes of NK or lymphokine activated killer (LAK) cell derivation has not yet been evaluated. We developed a murine model to evaluate the potential of LAK cells to localize into peripheral lymph nodes since LAK cells are used to treat human cancers which have metastasized to these tissues. Using a frozen section binding assay, LAK cell adhesion to the lymph node microvasculature was easily demonstrable. Inhibition studies demonstrated that LAK cell binding to lymph nodes was mediated by mechanisms previously described in T cells. LAK cell surface expression of the 85- to 95-kDa homing receptor recognized by the antibody MEL-14 on LAK cells was assessed by indirect immunofluorescence. The percentage of cells which bound MEL-14 decreased slightly over 3 days of IL-2 exposure (from 73 to 60%), particularly in the large granular lymphocyte (cytotoxic effector) subpopulation (45% MEL-14+). The expression of another homing-related molecule, leukocyte function-associated Ag-1, markedly increased during activation of LAK cells. Despite the expression of these homing receptors, we observed almost no LAK cell localization into lymph nodes in vivo. Furthermore, IL-2 pretreatment of recipient animals did not increase the adhesion of LAK cells to lymph node microvasculature or enhance their extravasation. IL-2 activation of non-T, non-B lymphocytes results in significant changes in both the expression and function of cell surface homing receptors. Our results indicate that in vitro analysis does not always predict in vivo localization potential.

Hypocholesterolemia in patients treated with recombinant interleukin-2: appearance of remnant-like lipoproteins

Reversible acute hypocholesterolemia was observed during treatment of metastatic cancer with high-dose intravenous recombinant interleukin-2 (IL-2). Further analysis revealed virtual disappearance of high-density lipoproteins (HDLs) and marked reduction in the concentration of low-density lipoproteins (LDL); the remaining LDL and intermediate-density lipoproteins (IDL) were enriched in triglyceride relative to cholesterol and had broad-beta electrophoretic mobility, properties reminiscent of remnant lipoproteins. These changes differ qualitatively and quantitatively from those previously reported for other cytokines such as tumor necrosis factor (TNF) or the interferons (IFNs).

Peripheral lymph node helper T-cell recovery after syngeneic bone marrow transplantation in mice prepared with either gamma-irradiation or busulfan

The optimum marrow ablative regimen for preparing recipients of bone marrow transplantation (BMT) has not been established. gamma-Irradiation, but not busulfan, produces a characteristic microvascular injury pattern which results in depressed capacity of normal lymphocytes to localize into the lymph nodes of syngeneic murine BMT recipients. Since peripheral lymph nodes are important sites for initiation and amplification of immune responses, the preparative regimen might delay recovery of regionally compartmentalized immune functions after BMT. We evaluated the effects of busulfan and gamma-irradiation on the phenotypic and functional reconstitution of helper T-cell function within the peripheral lymph nodes of BMT recipients. Both marrow ablative regimens caused a protracted delay in regeneration of peripheral lymph node CD4+ T cells. Specific helper T-cell functions, such as contact hypersensitivity and alloantigen responses, remained significantly depressed in the lymph nodes of irradiated mice for prolonged periods (up to 60 weeks). These responses recovered more rapidly in busulfan-treated BMT recipients. In contrast, the capacity of peripheral lymph node T cells to provide "help" for antigen-specific immunoglobulin production was only transiently depressed by either preparative regimen. Our experiments confirm the hypothesis that the marrow ablative regimen, particularly gamma-irradiation, may contribute to the period of immunodeficiency which follows BMT. The pattern of immune recovery observed suggests that preparative total body irradiation (TBI) may selectively depress the regional recovery of the TH1 [interleukin-2 (IL-2) and gamma-interferon (gamma-IFN) secreting] lymphocyte subset.

Severe myocarditis following high-dose interleukin-2 administration

We observed a patient who developed unusually severe myocardial dysfunction during therapy for renal cell carcinoma with high-dose interleukin-2 (IL-2). Although cardiac isoenzymes became markedly elevated shortly after the completion of 14 doses of IL-2 (100,000 U/kg of IL-2 every eight hours), serial electrocardiograms revealed only nonspecific changes. Echocardiography documented diffuse myocardial dysfunction, with akinesis of the anteroseptal region, suggestive of myocardial infarction. This anteroseptal hypokinesis persisted over a five-day period. The patient died unexpectedly and postmortem evaluation of the heart revealed a severe, diffuse lymphocytic, and eosinophilic myocarditis with myocyte necrosis, especially prominent in the anteroseptal region. This is the first histologically confirmed case of myocarditis reported, to our knowledge, in association with IL-2 therapy for cancer.

Liver sequestration of murine lymphokine activated killer (LAK) cells is mediated by carbohydrate-specific receptors

Intravenous infusion of radiolabeled lymphokine activated killer (LAK) cells into tumor bearing humans and animals results in retention of a large percentage (40-70%) of cells within the liver. Since LAK cell-tumor cell adhesion is believed to be necessary to initiate effective cytotoxicity, liver sequestration may decrease the therapeutic effectiveness of the adoptively transferred cells. We evaluated the mechanism of liver sequestration in a murine model. When 51Cr labeled LAK cells were infused intravenously into syngeneic recipients, about 45% of the radiolabeled cells were sequestered in the liver by 4 hours after infusion and 55% by 24 hours. Less than 0.4% of the infused cells localized into a 3-4 mm tumor implant. Peanut agglutinin (PNA), which recognizes galactose-terminal glycans, identifies cells at risk for sequestration by hepatic asialoglycoprotein receptors. We demonstrated that LAK cells, particularly the large granular lymphocyte subpopulations, were PNA high by direct immunofluorescence. The majority of LAK cell cytotoxic activity also resided in the PNA high cell population. Lectin blotting revealed that IL-2 incubation caused an increased expression of multiple cell membrane asialoglycoproteins. Experiments in vitro suggested that LAK cells were capable of binding to asialoglycoprotein and fucose-specific receptors within the liver. This binding could be inhibited by mild LAK cell surface trypsinization, suggesting that binding was mediated via cell surface glycoproteins. We conclude that LAK cells have a surface phenotype which can mediate their interaction with multiple hepatic carbohydrate-specific receptors. These interactions may result in LAK cell sequestration and decrease the delivery of cytotoxic cells into cancers during adoptive immunotherapy.