Response of psoriasis to a lymphocyte-selective toxin (DAB389IL-2) suggests a primary immune, but not keratinocyte, pathogenic basis

Psoriasis is a hyperproliferative and inflammatory skin disorder of unknown aetiology. A fusion protein composed of human interleukin-2 and fragments of diphtheria toxin (DAB389IL-2), which selectively blocks the growth of activated lymphocytes but not keratinocytes, was administered systemically to ten patients to gauge the contribution of activated T cells to the disease. Four patients showed striking clinical improvement and four moderate improvement, after two cycle of low dose IL-2-toxin. The reversal of several molecular markers of epidermal dysfunction was associated with a marked reduction in intraepidermal CD3+ and CD8+ T cells, suggesting a primary immunological basis for this widespread disorder.

Drug Monitoring of Antiretroviral Therapy for HIV-1 Infection: Method Validation and Results of a Pilot Study

Background: Antiretroviral therapy for HIV-1 infection has become increasingly complex. The availability of new and potent drugs and progress in understanding the pathogenesis of HIV-1 infection have led to the establishment of new treatment paradigms. The varying dosing regimens, associated toxicities, and the potential for drug-drug and food-drug interactions further complicate treatment. This complexity contributes to patient nonadherence. Because clinicians have no tools to monitor adherence or drug-drug interactions and because response requires that therapy exceed the known inhibiting concentration, serum monitoring of antiretroviral therapy may play a role in improving treatment of HIV-1 infection. We report methods to quantify serum concentrations of antiretroviral drugs used to treat HIV-1 infection, precision and interference studies of these methods, and results observed in a pilot evaluation of blood serum concentrations from 12 human subjects.

Methods: HPLC offers adequate sensitivity to measure peak or trough serum concentrations of delavirdine, lamivudine, nevirapine, indinavir, nelfinavir, ritonavir, and saquinavir and peak serum concentrations of stavudine, zidovudine, and didanosine with reasonable precision.

Results: Peak indinavir serum concentrations in most patients were in the range of 1–10 mg/L, and trough concentrations were in the range of 0.1–0.5 mg/L. Peak stavudine concentrations were in the range of 0.3–1.3 mg/L, and trough concentrations were in the range of 0.1–0.5 mg/L. Peak zidovudine concentrations were in the range of 0.1–1.1 mg/L.

Conclusions: Because this was a blood serum concentration-seeking pilot study to evaluate analytic performance, we do not report on the correlation of drug response to blood concentration. However, the concentrations observed in patients are generally consistent with blood concentrations reported from studies of monotherapy.

Reduction of vancomycin use in orthopedic patients with a history of antibiotic allergy

OBJECTIVE

To reduce prophylactic vancomycin use in patients with a history of penicillin or cephalosporin allergy undergoing elective orthopedic surgery by using a targeted allergy consultation and penicillin allergy skin testing.

PATIENTS AND METHODS

The participants in this practice improvement study were patients with a history of penicillin or cephalosporin allergy who were scheduled for elective orthopedic surgery and referred by orthopedic surgeons for allergy consultation and penicillin allergy skin testing between September 22, 1998, and April 15, 1999. The primary outcome measure was the percentage of participants who received prophylactic cefazolin during the study period compared with historical controls.

RESULTS

Of the 60 study patients, 59 received a penicillin allergy skin test, 58 underwent orthopedic surgery, and 55 received antibiotic prophylaxis. Fifty-five patients had a history of allergy to penicillin, a cephalosporin, or both, and 5 had a history of nonspecific antibiotic allergy. Of the 59 patients, 55 (93%) had negative penicillin allergy skin test results. Fifty-four (90%) of the 60 patients were given clearance by the allergist to receive cefazolin. Of the 55 study patients who received antibiotic prophylaxis, 6 (11%) received vancomycin compared with 38 (30%) of 127 historical controls (P < or = .05). None of the study patients had an immediate reaction to cefazolin or to vancomycin.

CONCLUSION

Prophylactic vancomycin use in patients with a history of penicillin or cephalosporin allergy undergoing elective orthopedic surgery can be reduced by a targeted allergy consultation and penicillin allergy skin testing.

Efficacy of HMAF (MGI-114) in the MV522 metastatic lung carcinoma xenograft model nonresponsive to traditional anticancer agents

Illudin analogs are cytotoxic to a variety of multidrug resistant cell lines, and display an unusual toxicity towards DNA helicase-deficient cell lines. Earlier illudin analogs demonstrated efficacy in several xenograft models, including a metastatic MV522 lung cancer model, resistant to conventional anticancer agents. These illudin analogs prolonged life span as compared to conventional agents, but did not induce complete remission of primary tumors. In vitro screening studies identified a semisynthetic derivative, hydroxymethylacylfulvene (HMAF, MGI-114), with increased selective cytotoxicity towards carcinoma cells. The HMAF analog was markedly effective in the experimental MV 522 metastasizing lung carcinoma xenograft system, a model refractory to treatment with existing anticancer agents. Treatment with paclitaxel, doxorubicin, or cisplatin failed to significantly inhibit primary tumor growth or prolong life span of MV522 tumor-bearing animals. Treatment with mitomycin C at the LD20 increased life span in surviving animals up to 61% (p = 0.04). Treatment with HMAF induced primary tumor regression in all animals and increased life span greater than 150% (p < 0.001). Thus, administration of HMAF inhibited development of lung metastasis in a model refractory to treatment with conventional anticancer agents. These results support further evaluation of HMAF as a therapeutic agent for treatment of solid tumors such as adenocarcinoma of the lung.

Characterization of illudin S sensitivity in DNA repair-deficient Chinese hamster cells. Unusually high sensitivity of ERCC2 and ERCC3 DNA helicase-deficient mutants in comparison to other chemotherapeutic agents

Illudins, novel natural products with a structure unrelated to any other known chemical, display potent in vitro and in vivo anti-cancer activity against even multi-drug resistant tumors, and are metabolically activated to an unstable intermediate that binds to DNA. The DNA damage produced by illudins, however, appears to differ from that of other known DNA damaging toxins. The sensitivity pattern of the various UV-sensitive cell lines differs from previously studied DNA cross-linking agents. Normally, the ERCC1- (excision repair cross complementing) and ERCC4-deficient cell lines are most sensitive to DNA cross-linking agents, with ERCC2-, ERCC3- and ERCC5-deficient cell lines having minimal sensitivity. With illudins the pattern is reversed, with ERCC2 and ERCC3 being the most sensitive. The sensitivity to illudins in complementation groups 1 through 3 is due to a deficiency of the ERCC1-3 gene products, as cellular drug accumulation studies revealed no differences in transport capacity or total drug accumulation. Also, a transgenic cell line in which ERCC2 activity was expressed through an expression vector regained its relative resistance to the illudins. The EM9 cell line, which displays sensitivity to monoadduct producing chemicals, was not sensitive. Thus, excision repair is involved in repair of illudin-induced damage and, unlike other anti-cancer agents, the involvement of ERCC2 and ERCC3 helicases is critical for repair to occur. The requirement for ERCC2 and ERCC3, combined with the finding that ERCC1 but not ERCC2 is upregulated in drug-resistant tumors, may explain the efficacy of illudins against drug-resistant tumors. The inhibition of DNA synthesis in cells within minutes after exposure to illudins at nanomolar concentrations may be related to the finding that the ERCC3 gene product is actually the p89 helicase component of the BTF2 (TFII) basic transcription factor and the high sensitivity of ERCC3-deficient cells to illudins.

Transfection with human copper-zinc superoxide dismutase induces bidirectional alterations in other antioxidant enzymes, proteins, growth factor response, and paraquat resistance

Transfection of a pSV2 human copper-zinc superoxide dismutase expression vector into murine fibroblasts resulted in stable transgenic clones producing increased amounts of copper-zinc superoxide dismutase. Two classes of transfectants were observed and were characterized by the presence or absence of an increase in endogenous glutathione peroxidase activity. In addition, increases and decreases in individual clones in the activities of manganese superoxide dismutase, glutathione reductase, and NADPH-reductase were detected. In general, these alterations in enzyme activity correlated to the cellular glutathione peroxidase/copper-zinc superoxide dismutase ratio. Parameters of cellular physiological functions were also altered, including cell division time, FGF and EGF response, fibronectin content, paraquat resistance, hydrogen peroxide release into media, and sensitivity to radiation. Some of these cellular parameters were also bidirectional and reflected the cellular glutathione peroxidase/copper-zinc superoxide dismutase ratio. Our results indicate that small deviations from the normal physiological copper-zinc superoxide dismutase/seleno-glutathione peroxidase ratios can have pronounced effects on other antioxidant enzymes, growth rate, growth factor response, and expression of proteins normally not associated with oxygen metabolism.

Efficacy of MGI 114 (6-hydroxymethylacylfulvene, HMAF) against the mdr1/gp170 metastatic MV522 lung carcinoma xenograft

Illudins are a novel class of agents with a chemical structure entirely different from current chemotherapeutic agents. A new semisynthetic derivative, MGI 114 (NSC 683,863, 6-hydroxymethyl-acylfulvene, HMAF), is markedly effective in a variety of lung, breast and colon carcinoma xenograft models. This analogue, MGI 114, is currently in phase I human clinical trials, and is scheduled for two different phase II trials. To determine if MGI 114 could be effective in vivo against mdr tumour cells, we generated an mdr1/gp170-positive clone of the metastatic MV522 human lung carcinoma line by transfecting a eukaryotic expression vector containing the cDNA encoding for the human gp170 protein. This MV522/mdr1 daughter line retained the metastatic ability of parental cells. The parental MV522 xenograft is mildly responsive in vivo to mitomycin C and paclitaxel, as evidenced by partial tumour growth inhibition and a small increase in life span, whereas MV522/mdr1 xenografts were resistant to these agents. In contrast to mitomycin C and paclitaxel, MGI 114 produced xenograft tumour regressions in 32 of 32 animals and completely eliminated tumours in more than 30% of MV522/mdr1 tumour-bearing mice. Thus, MGI 114 should be effective in vivo against mdr1/gp170-positive tumours.

Characterization of cellular accumulation and toxicity of illudin S in sensitive and nonsensitive tumor cells

Illudins are novel low molecular weight natural products cytotoxic to human tumor cells in vitro. Illudin-derived analogs are effective against experimental human cancers nonresponsive to conventional anticancer agents. It is not known why some illudin analogs are more efficacious in vitro and in vivo than other analogs. Therefore, the in vitro cytotoxicity of the parent compound illudin S towards tumor cells was characterized using radiolabeled drug. Two cell lines sensitive at nanomolar concentrations using only a 15-min exposure period displayed a saturable, energy-dependent accumulation of illudins with relatively low K(m) and high Vmax values. A nonsensitive cell line, requiring millimolar concentrations to achieve in vitro toxicity, showed minimal illudin uptake with higher K(m) and lower Vmax values. No release of radioactivity could be demonstrated from tumor cells, indicating that there was no efflux of illudin S (or metabolites) from these cells. The number of intracellular illudin S molecules required to kill 50% of cells of different tumor cell lines varied from 78000 to 1114000 molecules per cell and was correlated with the 2-h IC50 value determined using a colony-forming assay. Illudin S was cytotoxic to a variety of multidrug-resistant tumor cell lines regardless of whether resistance was mediated by gp170/mdrl, gp180/MRP, GSHTR-pi, topoisomerase I, topoisomerase II, increased DNA repair capacity, or alterations in intracellular thiol content. Information obtained in this study could be used to design clinical phase I trials and to develop analogs with improved therapeutic indexes.

Characterization of MGI 114 (HMAF) histiospecific toxicity in human tumor cell lines

PURPOSE

The acylfulvenes are a class of antitumor agents derived from the fungal toxin illudin S. One acylfulvene derivative, MGI 114 (HMAF), demonstrates marked efficacy in xenograft carcinoma models when compared to the parent acylfulvene or related illudin compounds. The maximum tolerated dose (MTD) of the two analogs in animals, however, is similar. To help elucidate the basis of the increased therapeutic efficacy of MGI 114, we determined the in vitro cytotoxicity, cellular accumulation and DNA incorporation of this drug and compared the results with those from the parent acylfulvene analog.

METHODS

The cytotoxicity of acylfulvene analogs was tested in vitro against a variety of tumor cell lines. Radiolabeled MGI 114 was used for cellular accumulation and DNA incorporation studies.

RESULTS

MGI 114 retained relative histiospecific toxicity towards myeloid leukemia and various carcinoma cell lines previously noted with the parent acylfulvene compound. Markedly fewer intracellular molecules of MGI 114 were required to kill human tumor cells in vitro as compared to the parent acylfulvene, indicating that MGI 114 was markedly more toxic on a cellular level. At equitoxic concentrations, however, the incorporation of MGI 114 into genomic tumor cell DNA was equivalent to that of acylfulvene. Analysis of cellular accumulation of MGI 114 into tumor cells revealed a lower Vmax for tumor cells, and a markedly lower Vd for diffusion accumulation as compared to acylfulvene.

CONCLUSIONS

The addition of a single methylhydroxyl group to acylfulvene to produce MGI 114 results in a marked increase in cytotoxicity in vitro towards tumor cells as demonstrated by the reduction in IC50 values. There was a corresponding decrease in the number of intracellular molecules of MGI 114 required to kill tumor cells, but no quantitative alteration in covalent binding of the drugs to DNA at equitoxic concentrations. This indicates that cellular metabolism plays a role in the in vitro cytotoxicity of MGI 114. The equivalent incorporation into genomic DNA at equitoxic doses suggests that DNA damage produced by acylfulvene and MGI 114 is equivalent in regard to cellular toxicity and ability to repair DNA. This increased cellular toxicity, together with the decrease in diffusion rate, may explain the increased therapeutic efficacy of MGI 114 as compared to the parent acylfulvene analog.

Review of pharmacokinetics and pharmacodynamics of antimicrobial agents

Pharmacokinetics is a science that has long been used in ascertaining the appropriate antimicrobial dose. It refers to the disposition of drugs in the body and includes absorption, bioavailability, distribution, protein binding, metabolism, and elimination. Pharmacodynamics is a newer science that relates to the interaction between the drug concentration at the site of action over time and the desired antimicrobial effect. This article reviews the principles of pharmacokinetics and pharmacodynamics as well as the clinical application of these two sciences to design antimicrobial dosing regimens for optimal results in individual patients.

Heterologous expression of carbonyl reductase: demonstration of prostaglandin 9-ketoreductase activity and paraquat resistance

Transfection of murine NIH3T3 fibroblasts with a pSV2-derived eukaryotic expression vector for human cytosolic carbonyl reductase (E.C. 1.1.1.141) resulted in clones with increased carbonyl reductase activity as demonstrated by an elevation in cellular NADPH-dependent alcohol (menadione) reductase activity. Prostaglandin 9-ketoreductase (9KR) activity, previously noted only in purified enzyme preparations, was also elevated. Although the cellular molar capacity of 9KR activity was less than menadione reductase activity (picomoles versus nanomoles per mg of protein), when compared to endogenous activity there was a greater relative increase in 9KR activity as compared to menadione activity (10 fold increase versus 3 fold). Thus, the 9KR properties of carbonyl reductase may have a physiologic role in prostaglandin regulation. Most transgenic clones lost their enhanced carbonyl reductase activity despite continuous selection, but two clones retained enhanced enzyme activity. RNA analysis indicated that these two murine clones expressed human carbonyl reductase mRNA. These two clones overexpressing carbonyl reductase did not display resistance to menadione, in agreement with a previous report. There was, however, a demonstrable increase in resistance to paraquat of a magnitude similar to that previously noted with transgenic cell lines overexpressing manganese superoxide dismutase.

Anti-leukemic action of the novel agent MGI 114 (HMAF) and synergistic action with topotecan

The illudin derivative MGI 114 (6-hydroxymethylacylfulvene or HMAF) is currently in phase II chemotherapeutic clinical trials for a variety of solid tumors. The illudins were originally thought to be potentially useful agents for myeloid leukemias, because hematopoietic tumor cells were markedly sensitive whereas normal bone marrow progenitors were relatively resistant to the cytotoxic effects of illudins. Due to the marked preclinical efficacy of MGI 114 against a variety of solid tumor xenografts, the current phase II human trials are restricted to solid tumor (breast, lung, colon, ovarian, pancreas, prostate, etc) malignancies. The present studies were undertaken to evaluate the efficacy of MGI 114 in the HL60/MRI myeloid leukemia xenograft. In addition, because of the reported synergistic cytotoxic activity between MGI 114 and the topoisomerase I inhibitor topotecan towards pediatric human tumor cell lines, we tested the activity of MGI 114 and topotecan combinations against HL60 cells in vitro and the HL60/MRI myelocytic xenograft. Our results indicate that MGI 114 at maximum tolerated doses (MTD) of 7 mg/kg, five times per week for 3 weeks does display anti-myeloid leukemic properties in the HL60/MRI xenograft model which exceeds activity noted with other conventional agents (TGI > 70%). A marked therapeutic synergistic action was observed with MGI 114 and topotecan combinations of (1/2) MTD of each agent producing complete tumor remission in 50% of animals, without development of excessive or additive toxicity in animals. These results support further in vitro and clinical investigation into both the anti-myeloid leukemic activity of MGI-114, and the cooperative pharmacologic interaction noted between MGI-114 and topoisomerase I inhibitors. Leukemia (2000) 14, 136-141.

Morphologic alterations of rat Leydig cells induced by ethanol

Ultrastructural morphometric studies were employed to compare the morphology of Leydig cells found in the testes of rats fed ethanol, accounting for 36% of total calories for 6 weeks, and those found in the testes of rats isocalorically fed a diet in which ethanol was isocalorically replaced with dextrimaltose. The testes of alcohol-fed rats weighed significantly less (p less than 0.01) than those of the isocaloric controls. Moreover, plasma testosterone in the alcohol-fed animals was reduced (p less than 0.01), as compared to the controls. Morphologically, two main differences were encountered between the Leydig cells of alcohol-fed animals and those of the isocalorically-fed controls. These were: (1) an increase in the number of elongated and cup-shaped mitochondria; and (2) an increase in cytoplasmic protrusions in the form of pseudopods. Using morphometric techniques, the Leydig cells of alcohol-fed animals were smaller (p less than 0.05), had less cytoplasm (p less than 0.05), larger mitochondria (p less than 0.01), and less smooth endoplasmic reticulum (p less than 0.05) than did those of the isocaloric controls. These morphologic characteristics of Leydig cells of alcohol-fed animals are similar to those reported to occur in the liver and suggest that the biochemical mechanisms responsible for alcohol-induced cellular injury are similar in the testes and the liver.

Characterization of acylfulvene histiospecific toxicity in human tumor cell lines

PURPOSE

Acylfulvene derivatives demonstrate marked efficacy in xenograft carcinoma models as compared with the parent illudin compounds. To elucidate the increased therapeutic efficacy of acylfulvene analogs, we compared them with the illudin compounds in terms of their in vitro cytotoxicity, cellular accumulation and DNA incorporation.

METHODS

The cytotoxicity of various acylfulvene analogs was tested in vitro against a variety of tumor cell lines. Radiolabelled acylfulvene analog was prepared and used for cellular accumulation and DNA incorporation studies.

RESULTS

The prototype acylfulvene analog retained selective histiospecific toxicity towards myeloid leukemia and various carcinoma cell lines. In vitro killing of tumor cells by acylfulvene required up to a 30-fold increase in molecules per cell, as compared with illudin S, indicating that acylfulvene was less toxic on a cellular level. At equitoxic concentrations, acylfulvene incorporation into genomic tumor cell DNA was equivalent to illudin S suggesting that cellular metabolism has a role in acylfulvene cytotoxicity. Analysis of cellular accumulation of acylfulvene into tumor cells revealed a markedly higher Vmax for tumor cells, and a lower Vd for diffusion accumulation into other cells.

CONCLUSIONS

The combination of higher Vmax and lower Vd may explain the increased in vivo efficacy of acylfulvene.

1243. Comparative Analysis of Antimicrobial-related Adverse Events in the Outpatient Treatment of Staphylococcal Infections

Background

Limited data exist to evaluate safety-related outcomes in Outpatient Parenteral Antimicrobial Therapy (OPAT) patients treated with antimicrobial agents for Gram-positive infections.

Methods

This retrospective, single-center study enrolled Mayo Clinic OPAT patients between 2013 and 2017. The primary objective of the study compared rates of therapy modification due to drug-related toxicity for staphylococcal infections treated with ceftriaxone, cefazolin, nafcillin, oxacillin, vancomycin, daptomycin, ceftaroline, linezolid, or ertapenem. Secondary objectives included determination of the frequency and type of adverse drug events (ADEs) attributed to OPAT and rate of readmission due to ADEs attributed to OPAT.

Results

One hundred seventy-two patients were identified (cefazolin n = 54, ceftriaxone n = 49, vancomycin n = 30, daptomycin n = 16, nafcillin n = 9, ertapenem n = 6, ceftaroline n = 4, oxacillin n = 3, linezolid n = 1). The overall treatment completion rates were high (153/172, 89.0%). Patients completed an average of 35.3 days (7 to 95) of therapy with their original antibiotic. Fourteen patients required change to a different antibiotic due to antimicrobial toxicity (ceftriaxone=5; vancomycin=2; cefazolin = 2; daptomycin = 2; ceftaroline = 1; nafcillin = 1; oxacillin = 1) and five patients experienced treatment failure required an additional agent (ceftriaxone = 2; nafcillin = 2; linezolid = 1). Adverse drug events (ADEs) were the most common reason for antimicrobial adjustment (14/19, 73.7%). The most common ADEs were hypokalemia (28/172, 16.3%) and diarrhea (25/172, 14.5%). There were only two cases of Clostridium difficile. Thirty-day readmissions due to antimicrobial therapy were low with 11 patients.

Conclusion

OPAT with Gram-positive agents used for staphylococcal infections is effective, but antimicrobial modifications still occur. Clinicians should be aware of the risk of ADEs and readmissions in OPAT patients. A multidisciplinary approach may enhance management of ADEs and possibly preventing readmissions

Disclosures

All authors: No reported disclosures.

Drug monitoring of antiretroviral therapy for HIV-1 infection: method validation and results of a pilot study

BACKGROUND

Antiretroviral therapy for HIV-1 infection has become increasingly complex. The availability of new and potent drugs and progress in understanding the pathogenesis of HIV-1 infection have led to the establishment of new treatment paradigms. The varying dosing regimens, associated toxicities, and the potential for drug-drug and food-drug interactions further complicate treatment. This complexity contributes to patient nonadherence. Because clinicians have no tools to monitor adherence or drug-drug interactions and because response requires that therapy exceed the known inhibiting concentration, serum monitoring of antiretroviral therapy may play a role in improving treatment of HIV-1 infection. We report methods to quantify serum concentrations of antiretroviral drugs used to treat HIV-1 infection, precision and interference studies of these methods, and results observed in a pilot evaluation of blood serum concentrations from 12 human subjects.

METHODS

HPLC offers adequate sensitivity to measure peak or trough serum concentrations of delavirdine, lamivudine, nevirapine, indinavir, nelfinavir, ritonavir, and saquinavir and peak serum concentrations of stavudine, zidovudine, and didanosine with reasonable precision.

RESULTS

Peak indinavir serum concentrations in most patients were in the range of 1-10 mg/L, and trough concentrations were in the range of 0.1-0.5 mg/L. Peak stavudine concentrations were in the range of 0.3-1.3 mg/L, and trough concentrations were in the range of 0.1-0.5 mg/L. Peak zidovudine concentrations were in the range of 0.1-1.1 mg/L.

CONCLUSIONS

Because this was a blood serum concentration-seeking pilot study to evaluate analytic performance, we do not report on the correlation of drug response to blood concentration. However, the concentrations observed in patients are generally consistent with blood concentrations reported from studies of monotherapy.