Ehrlich II –2nd World Conference on Magic Bullets

Therapeutic Vaccination For Lymphomas: Challenges And Opportunities NEELAPU SS Department of Lymphoma and Myeloma, The University of Texas M. D. Anderson Cancer Center, Houston, TX, USA Immunotherapy is a promising approach for the treatment of follicular lymphoma (FL), the most common low-grade B-cell non-Hodgkin’s lymphoma that is considered incurable and results in fatal outcome in the majority of patients. Immunization with customized vaccines made from the clonal tumor immunoglobulin molecule, termed idiotype, induced tumor-specific T-cell immunity in greater than 80% of patients with lymphoma. However, objective clinical responses were observed in only a minority of patients following idiotype vaccination. Although the magnitude or quality of the immune responses may be a reason for the low clinical response rate, resistance to the effector phase of the antitumor T-cell response due to immunosuppressive mechanisms in the tumor microenvironment is also thought to play a major role. Important negative regulatory pathways that inhibit T-cell function include extrinsic suppression by regulatory T cells, direct inhibition through inhibitory ligands such as PD-L1, and metabolic dysregulation of essential amino acids such as tryptophan. The relative contributions of these inhibitory processes will be reviewed and novel approaches to enhance the efficacy of therapeutic vaccination strategies in human lymphomas will be discussed.

Antibiotic Treatment For Clostridium Difficile-Associated Diarrhea In Adults NELSON R Department of Surgery, Northern General Hospital, Sheffield, UK. S5 7AU Background: The aim of this review is to establish the efficacy of antibiotic therapy for C. difficile-associated diarrhea (CDAD), to identify the most effective antibiotic treatment for CDAD in adults. Methods: Only randomized, controlled trials assessing antibiotic treatment for CDAD were included. The following outcomes were sought: resolution of diarrhea; conversion of stool to C. difficile cytotoxin and/or stool culture negative; recurrence of diarrhea; recurrence of fecal C. difficile cytotoxin and/or positive stool culture; patient response to cessation of prior antibiotic therapy; sepsis; emergent surgery: fecal diversion or colectomy; and death. For dichotomous outcomes, relative risks (RR) and 95% confidence intervals (CI) were derived from each study. When appropriate, the results of included studies were combined for each outcome, using a fixed effect model, except where significant heterogeneity was detected, at which time the random effects model was used. Results: Twelve studies (1157 participants with CDAD) were included. Eight different antibiotics were investigated: vancomycin, metronidazole, fusidic acid, nitazoxanide, teicoplanin, rifampin, rifaximin and bacitracin. In paired comparisons, no single antibiotic was clearly superior to others, though teicoplanin, an antibiotic of limited availability and great cost, showed in some outcomes significant benefit over vancomycin and fusidic acid, and a trend towards benefit compared to metronidazole. Only one placebo controlled trial was done and no conclusions can be drawn from it due to small size and classification error. Only one study investigated synergistic antibiotic combination, metronidazole and rifampin, and there was no advantage to the drug combination. Conclusions: The only placebo-controlled study shows vancomycin’s superior efficacy. However, this result should be treated with caution. The study of asymptomatic carriers also shows that placebo is better than vancomycin or metronidazole for eliminating C. difficile in stool during follow-up. Two goals of therapy need to be kept in mind: improvement of the patient’s clinical condition and prevention of spread of C. difficile infection to other patients. Given these two considerations, one should choose the antibiotic that brings both symptomatic cure and bacteriologic cure. In this regard, teicoplanin appears to be the best choice. Teicoplanin is not readily available in the United States, which must be taken into account when making treatment decisions in that country

Levofloxacin For Typhoid Fever : An Unparalelled Local Success Story NELWAN RHH Division of Tropical and Infectious Diseases, Department of Internal Medicine, Medical Faculty University of Indonesia, Jakarta, Indonesia Fluoroquinolones especially Ciprofloxacin emerged as a drug of choice for treating typhoid fever during the last decade of the previous century while Levofloxacin acquired the prestigious title of Respiratory Quinolone due to its action by obtaining very high drug concentration both in the alveolar macrophages as well as lung tissue and its ability to destroy the Atypical Respiratory Pathogens. Because of a trend reported at the end of the previous century concerning decreased sensitivity of Salmonella typhi against ciprofloxacin the application to study hospitalized uncomplicated typhoid fever patients with oral levofloxacin was granted by the Faculty of Medicine University of Indonesia, Jakarta. This initial open study using 500 mg of levofloxacin once daily for 7 days consisted of 53 screened hospitalized typhoid fever patients enrolling 48 patients of them in whom 31 cases were positive by either blood culture or polymerase chain reaction or by significant serological increase of titers. From these 31 cases one cases was later excluded because of a concomittant sinus infection. After the astonishing result of resolution of fever within 2.5 days with a minimum number of side effects which were all tolerable and without any clinical relapse or S. typhi fecal carrier state one month post treatment, it was decided to continue the study and compare two regimens of treatment for uncomplicated typhoid fever. A random single blind comparative study of 500 mg ciprofloxacin twice daily for one week against once a day 500 mg levofloxacin also for one week was proposed that also received full support by the ethical committee of the Faculty. This study was carried out as a multicenter study encompassing five other medical faculties. One important criteria to mention was that all cased that did not obtain defervescence after the treatment-week with either ciprofloxacin or levofloxacin were given 500 mg ciprofloxacin as long as needed for obtaining clearance of fever. From 212 screened hospitalized suspected typhoid fever cases, definite infection was confirmed in 110 cases consisting of 54 cases in the levofloxacin arm and 56 cases in ciprofloxacin arm. Baseline characteristics like sex, age, length of illness and clinical score were statistically not different for both groups. Results favored better fever clearance in the levofloxacin group. Two clinical relapses occurred in the ciprofloxacin group and was confirmed by microbiological culture. Clinical adverse reactions were on the whole less in the levofloxacin group while the laboratory side effects were twice as many with more than 3 times increase of SGPT in the ciprofloxacin group of patients. The final study comparing levofloxacin IV and ciprofloxacin IV in complicated typhoid fever showed that in the toxic patient the clinical condition without resorting to the use of corticosteroids which are usually routinely administered in the toxic patient converted spontaneously. A positive imunomodulatory effect probably made a significant contribution to the reversal of the toxic delirious typhoid fever patient to become fully alert again. Perhaps at the moment we have an improved MAGIC BULLET for treatment of a life threatening condition that is especially still rampant in many countries of South and South East Asia.

Levamisole Resistance In Parasitic Nematodesinvestigated At The Molecular Level NEVEU C, CHARVET C, FAUVIN A, CORTET J, CABARET J French National Institue for Agricultural Research  ( INRA ), UR1282, Infectiologie Animale et Santé Publique, Centre de recherche de Tours, Nouzilly, France The nicotinic acetylcholine receptor (nAChR) is an important determinant of signal transmission at the neuromuscular junction. Helminth nAChRs are selectively targeted by many drugs such as the anthelmintic family agents imidazothiazoles (e.g., levamisole). However, the high efficacy of levamisole treatments against gastrointestinal parasitic nematodes of ruminants has been compromised by the development of resistance in field parasite populations. In order to investigate molecular mechanisms involved in levamisole resistance a candidate gene strategy has been initiated. In the free-living nematode Caenorhabditis elegans, the levamisole-sensitive nAChR is composed of five multi-transmembrane spanning subunits encoded by unc-29, lev-1, unc-63, unc-38 and lev-8 genes and mutants lacking one of those genes are resistant to levamisole. Here we have identified and sequenced unc-29, lev-1, unc-63 and unc-38 orthologs isolated from the trichostrongylid nematode Haemonchus contortus that is causing major economic losses to sheep industry throughout the world. Expression studies of those genes in levamisole resistant and susceptible isolates of H. contortus revealed specific expression of alternatively spliced RNA messenger in resistant isolates. If the alternative splicing of nAChR subunits is well documented in insects, this work constitutes to our knowledge the first report of such a phenomenon in nematodes.

Longterm Therapy Of Brain Tumors With Temozolomide: Review Of Tolerability And Efficacy In 53 Patients Newton HB^1, Dalton J^1, Figg G^1, Volpi C^1, Pearl D^2 Departments of ^1Neurology and ^2Statistics; The Ohio State University Medical Center and James Cancer Hospital and Solove Research Institute, Columbus, OH, USA Background: Temozolomide (TZM) is a 2^nd generation alkylating agent with significant efficacy for low-grade and malignant brain tumors. The drug is administered orally for 5 days every month (150-200 mg/m^2/day), using a conventional schedule. Due to TZM’s excellent tolerability and lack of cumulative systemic toxicity, some patients are receiving treatment for 12 to 24 months. The efficacy, safety, and tolerability of this longterm therapeutic approach remains unclear. Methods: We performed a retrospective chart review of all Neuro-Oncology Center patients who had undergone temozolomide chemotherapy for 12 months or longer. Results: A total of 53 patients (median age 45 years) met the criteria; tumor types included glioblastoma multiforme (GBM; 17), oligodendroglioma (10), anaplastic glioma (12), astrocytoma (6), other glioma (7), and primary CNS lymphoma (1). Forty-one patients had received irradiation; 10 had prior chemotherapy. The median number of monthly TZM cycles was 20 (range 12-28; 38 patients  18 cycles), with a median TZM dose of 400 mg/day. Median time to progression was 34+ months (range 14 to 65+ months; 30+ months in GBM cohort), with 15 objective responses by MRI (28.3%). Toxicity included mild to moderate fatigue (98%), mild nausea (85%), constipation (70%), and grade I/II leukopenia (66%) and thrombocytopenia (47%). Of 1087 total cycles of TZM, 18 (1.7%) were delayed at least one week by treatment-related side effects. No lymphoproliferative disorders have been documented. Conclusions: Longterm treatment with TZM is feasible, and demonstrates durable activity and acceptable toxicity in patients with gliomas, including GBM.

In Vitro Pharmacodynamic Evaluation Of Intracellular Activity Of Antibiotics (ABs) Alone Or In Combination Against A Small Colony Variant (SCV) Of Staphylococcus Aureus NGUYEN HA^1, DENIS O^2, VERGISON A^2, TULKENS PM^1, STRUELENS MJ^1, VAN BAMBEKE F^1 ^1Université catholique de Louvain, ^2Université libre de Bruxelles, Brussels, Belgium Background: SCVs show reduced AB susceptibility and persist intracellularly, which may cause therapeutic failures. The intracellular activities of OXA (oxacillin), FA (fusidic acid), CLI (clindamycin), GEN (gentamicin), RIF (rifampin), VAN (vancomycin), LNZ (linezolid), Q-D (quinupristin-dalfopristin), DAP (daptomycin), TGC (tigecycline), MXF (moxifloxacin), TLV (telavancin), and ORI (oritavancin), alone or in combination, were examined in THP-1 macrophages infected by a stable thymidine-dependent SCV in comparison with normal phenotype and revertant isogenic strains isolated from the same cystic fibrosis patient. Methods: Intracellular activities were determined in THP-1 macrophages after 24 h or 72 h of exposure to ABs. Combinations were tested at fixed concentrations and then using the Fractional Maximal Effect method (FME). Results: At Cmax, ORI caused a 2 log CFU reduction at 24 h, RIF, MXF, and Q-D, a similar reduction at 72 h. All other ABs showed a static effect at 24 h and 1 log CFU reduction at 72 h. Dose effect studies showed a bimodal curve with 2 successive plateaus at  0.4 and  3.1 log CFU for ORI; maximal effects of -1.1 to -1.7 log CFU for TGC, MXF, and RIF, and of     0.6 log CFU for the other ABs. Addition of thymidine restored the SCV intracellular growth, but did not modify the AB activity except for Q-D. All drugs showed higher intracellular activity against normal or revertant phenotypes than against SCVs, except TGC and ORI. At Cstatic, all combinations with RIF or ORI proved more active (in particular OXA, GEN and MXF). At Cmax, all combinations with RIF were less active than RIF alone, while combinations of ORI with GEN, Q-D, or RIF were more active than ORI alone. Using the FME method, RIF and ORI were synergistic at all concentration ratios investigated, ORI and MXF were also synergistic but at large ORI concentrations only. RIF and MXF were additive. Conclusion: Intracellular SCV are poorly susceptible to most ABs, which may contribute to the difficulty of eradicating such infections. Our studies may help in selecting most active drugs or appropriate combinations to rationalize AB treatment of persistent infections involving SCVs.

Doripenem, A New Carbapenem: Optimizing Dose To Treat Increasingly Resistant Gram-Negative Pathogens. NICHOLSON SC^1, PETERSON JA^1 ^1Ortho-McNeil Janssen Scientific Affairs, LLC, Raritan, NJ, USA. Background: The growing number of infections due to multi-drug resistant (MDR) Gram-negative pathogens such as Pseudomonas aeruginosa has prompted exploration for new, highly effective anti-infective agents as well as the more rational use of available anti-infectives. Doripenem is a new carbapenem with increased in vitro microbiologic potency, low potential for seizure induction, and prolonged stability in solution. Methods: These features allow for increased dose and prolonged infusion duration, which optimizes the carbapenem time-dependent pharmacokinetics and pharmacodynamics (PK/PD), and hopefully increases clinical efficacy against serious Gram-negative infections while minimizing the emergence of resistance. Results: Doripenem has been studied at 500 mg infused over 1 hour Q8H for the treatment of complicated urinary tract infections, intraabdominal infections, and nosocomial pneumonia. A prolonged infusion of the 500 mg dose over 4 hours has been studied in later-onset ventilator-associated pneumonia, acknowledging that pathogens with higher carbapenem MICs are more likely in this patient population. Additional studies are underway with a 1-gram dose infused over 4 hours in patients with nosocomial pneumonia, including ventilator-associated pneumonia, who are at particular risk of carbapenem resistant P. aeruginosa infection. Exploiting the safety of high dose doripenem and the longer stability in solution, strategies to increase the time over MIC of this highly potent carbapenem, theoretically allows for the treatment of infections due imipenem- resistant pathogens where other therapeutic options are severely limited. Conclusion: In summary, doripenem holds promise as a new “magic bullet” for the treatment of infections involving MDR Gram-negative pathogens, particularly Pseudomonas aeruginosa. Authors’ disclosure statement: Susan C. Nicholson and Janet A. Peterson are employees of Ortho-McNeil Janssen Scientific Affairs, LLC.

Sugammadex A Novel Cyclodextrin For The Reversal Of Neuromuscular Blockade NICHOLSON WT, SPRUNG J, JANKOWSKI CJ Mayo Clinic, Rochester, MN, USA Background: Following surgery, reversal of the non-depolarizing effects on skeletal muscle relaxation is facilitated by the administration of an acetylcholinesterase inhibitor. Although effective, this method of reversal presents issues including muscarinic adverse effects and administration timing. Sugammadex is a modified gamma-cyclodextrin compound pharmacologically unrelated to the acetylcholinesterase inhibitors. Currently, pharmaceutical uses of cyclodextrins have been primarily limited to excipients in drug formulation. Sugammadex is a selective relaxant binding agent, which forms a 1:1 complex with steroidal non-depolarizing neuromuscular blockers within the plasma. This results in lowering the availability of the neuromuscular blocker at the nicotinic receptor. Unlike acetylcholinesterase inhibitors, prior studies have demonstrated that sugammadex can elicit rapid reversal during profound neuromuscular block. Methods: Using acceleromyography, we describe reversal in two surgical cases requiring pharmacologic reversal of neuromuscular blockade. The primary outcome measure was a train of four ratio (TOF) of 0.9. In the first case, the acetylcholinesterase inhibitor neostigmine antagonized the effects of non-depolarizing blockade with rocuronium and vecuronium. In a subsequent case, sugammadex was administered for reversal of rocuronium-induced neuromuscular blockade. Results: Both methods employed for reversal were effective. The TOF ratio of 0.9 was achieved 4 min, 41 sec after administration of neostigmine following partial spontaneous recovery of TOF ratio (0.5) and 1 min, 14 sec with sugammadex following partial spontaneous recovery of TOF ratio (0.25). Additionally, after a TOF ratio of 0.9 was achieved in the neostigmine-treated patient, there was a period of 4 min, 15 sec when the ratio decreased to below the desired level of 0.9. In contrast, the TOF ratio was maintained at 0.9 or higher in the sugammadex-treated patient, once a level of 0.9 was obtained. Conclusions: Sugammadex provides novel approach for the reversal of amino-steroidal induced neuromuscular blockade. In contrast to acetylcholinesterase inhibition, sugammadex does not increase endogenous levels of acetylcholine or require the co-administration of anticholinergic agents. Authors’ disclosure statement: The authors and the Mayo Clinic College of Medicine have conducted sponsored clinical research studies of sugammadex for Organon/ Schering Plough.