Progress report of the macrofil chemotherapy project for 1992-93

aWORLD HEALTH ORGANIZATION ORGANISATION MONDIALE DE LA SANTE ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA PROGRAMME DE LUTrE CONTRE L'ONCHOCERCOSE EN AFRIQUE DE L'OUEST EXPERT ADVISORY COMMITTEE Fourteenth session Ouaeadoueou. 7-l I June I993 ocP/EACr4.3 ENGLTSH ONLY PROGRESS REPORT OF THE MACROFIL CHEMOTHERAPY PROJECT FOR 1992-93 SUMMARY l. The current status of potential macrofilaricides is summarized. Clinical information on amocarzine (CGP 6140) is being collated by Ciba-Geigy for possible registration in Switzerland. Macrofil would undertake limited trials of the drug on the basis of satisfactory documentation on its safety and efficacy being made available to the Project. 2. Ciba-Geigy has completed essential toxicology studies on CGI 18041, and some anaemia was produced following 28 consecutive days of dosing with the drug. The compound has shown good macrofilaricidal activity in a single, oral dose, but would only go to Phase I clinical trials if additional preclinical toxicology was satisfactory. Ciba-Geigy has indicated that such a decision can be made later in 1993. UMF 078 is about to enter preclinical development. This benzimidazole derivative has shown good macrofilaricidal activity both by the intramuscular route and orally. Both the chemical structure and route of synthesis are novel, and Macrofil has collaborated with the University of Michigan to file US patents and also patents to cover countries of manufacture and use. Macrofil has approached possible partners in the pharmaceutical industry to discuss joint development of the compound. 3. To expand the compound screening programme, the objective is to increase the number of compounds tested, mainly by putting in place legal agreements with pharmaceutical companies, but also by searching commercial chemical libraries. Major efforts are being made to set up the infrastructure to handle and store the compounds themselves, and to set up a computerized data base to handle associated chemical and biological information generated by the screening programme. With the establishment of a second cattle screening centre many more lead compounds from primary and secondary screening will be synthesized in sufficient quantity for such assays against Onchocerca species. The drug development pathway currently used by the Macrofil Project is shown as Appendix l. 4. Research to identify new chemotherapeutic targets continues, as does possible resistance to ivermectin in onchocerciasis. From the latter studies it is hoped that a "molecular probe" can be developed which would identify resistant genes in Onchocerca. \ ocP/EACl4.3 Page 2 5. Great administrative changes are to be made in TDR, including the loss of the TDR/Filariasis Steering Committee. However, the Macrofil Chemotherapy Project will continue unchanged within the,Product Development Unit of TDR. 6. Two additional appendices give details of the research projects currently funded(Appendix 2), and a list of members of the Macrofil Steering Committee (Appendix 3). CURRENT STATUS OF MACROFILARICIDE DEVELOPMENT I. COMPOUNDS IN CLINICAL TRIALS l.l. Amocarzine (CGP 6140) - Ciba-Geiev Ciba-Geigy continues to support clinical trials of amocarzine in Latin America at no cost to OCP. An oral dosing schedule of 5 mg/kg daily on two subsequent days has been used, and proof of macrofilaricidal activity of this schedule is awaited. Such a dosing regimen, used in the community, would be more acceptable than the currently used three-day/six-dose regimen. The company is still examining all available clinical data, with a plan to submit this to the Swiss Regulatory Authorities (IKS) for approval. Additionally, the currently used route of chemical synthesis is environmentally unacceptable, and new synthetic routes are being examined. With drug synthesized by a new route there may be a need for some toxicological itudies, andproduction of new, marketable material is not anticipated until mid-1995. Experimental drug however, should continue to be available. If the final summary of clinical data indicates acceptable efficacy and safety, then amocarzine should enter into further trials for onchocerciasis in Africa, and for lymphatic filariasis. 1.2. Hieh-doseivermectintreatments Single doses of A00 yg/kg and 600 yg/ke have been used safely in man against various filarial infections, and the 4001tg/kg dose has been used every two weeks for six months against Wuchereia bancrofti infections in Sri Lanka. While the parasitological outcome of this latter study is unknown, the drug regimen was clinically acceptable. A revised protocol for a high-dose safety and efficacy study of ivermectin in onchocerciasis has been submitted to Merck Sharp & Dohme and the WHO Secretariat Committee for Research Invoii,ing Human Subjects. This siudy would be carried out at the onchocerciasis Chemotherapy Research Centre, Ghana under the direction of Dr K. Awadzi, and would investigate the possible macrofilaricidal action of high and repeated doses of ivermectin. 1.3. Additional clinical trials centres If required, clinical trials of potential macrofilaricides for onchocerciasis can be carried out in Enugu, Nigeria and Yaound6, Cameroon. For lymphatic filariasis, clinical centres in Asia, Africa and Latin America, currently being used for studies of diethylcarbamazine and ivermectin, will be made available through the Special Programme for Research and Training in Tropical Diseases (TDR). Final reports on the toxicity, drug metabolism and pharmacokinetics have been received and reviewed by the Secretariat and Steering Committee- The toxicological reports will be sent for external review by an independent consultant. ocP/EACl4.3 Page 3 2. COMPOUNDS IN PRECLINICAL DEVELOPMENT 2.1. CGI 18041 - Ciba-Geiev Anaemia was produced in both the dog and rat during 28 consecutive days of dosing but this was not severe and would not seem to preclude Phase I clinical trials in humans. Manager, Macrofil and Chief, Filariasis Control, Division of Control of Tropical Diseases (CTD) will participate in a Ciba-Geigy meeting in May 1993 to discuss the future of antifilarial drug development within the company. It will be suggested to Ciba-Geigy that further toxicological studies are required to find the drug dose and time when anaemia appears, and to further identify and quantify metabolites of the parent drug. It is hoped that the company will continue to fund these preclinical studies which are needed before Phase I trials can be initiated. 2.2. UMF 078/289 - Universitv of Michiean In view of the good macrofilaricidal activity of the benzimidazole compound UMF 078 preclinical toxicity and efficacy studies will continue with urgency. The Ash Stevens laboratory (USA) has been contracted to manufacture UMF 078 in kilogram quantities and is being supplied with flubendazole of high quality purchased from the Republic of Korea as starting material. An analytical laboratory (SRI International, USA) has been contracted to develop assays, define standards and assay new synthetic lots as required. Formulation of oral, intramuscular and intravenous preparations for studies of toxicity, irritancy and efficacy, and for metabolic and pharmacokinetic studies have been supplied by the University of Iowa. Present information suggests that UMF 078 is a bioavailable prodrug of flubendazole, which may be helpful in prediction of metabolites. However, unlike flubendazole or mebendazole, UMF 078 has a chiral centre at a substituent carbon atom and therefore exists as two enantiomers. These have been partially separated by column chromatography but pure preparations of both enantiomers need to be made available to determine efficacy and toxicity of each enantiomer. All studies in the past and in the near future make use of a racemic mixture. The synthesis and activity of UMF 078 and related compounds were patented in the USA by the University of Michigan in May 1992, and the agreement between the University and WHO for further development was signed on l8 January 1993. A further filing of patents for countries other than the USA has been requested and will be at the cost of WHO. With the patents and agreement noted above WHO representatives visited Janssen Pharmaceutica (Belgium) to discuss development of the compound. The company offered help in some of the chemical areas, and may be able to supply H31Cra-radiolabelled flubendazole which would form a starting material for the radiolabelled UMF 078 required for metabolic studies. Two grams of UMF 078 have been sent to Janssen to allow the company to examine the spectrum of activity of the compound against other parasitic nematodes. ln February 1993 Manager, Macrofil, together with Dr P. Reeve (Head of TDR's Product Development Unit), visited laboratories in India (Indian Institute of Chemical Research and Dr Reddy's Foundation) which could also assist in preparation of enantiomers of UMF 078 if required. ocP/EACt4.3 Page 4 3. DRUG SCREENING ACTIVITIES 3.1. Availabilitv of test comoounds Companies continue to supply compounds for testing in Macrofil-sponsored in vitro and in vivo assays. However, to increase compound numbers and novelty of structure some compounds will be purchased from commercial catalogues. Director, TDR has recommended that centralized compound holding and shipping facilities, together with a computerized data base, should be used for the three disease programmes actively undertaking drug development, i.e. filariasis, malaria and trypanosomiasis/leishmaniasis, and Macrofil will be an active member of this grouping. 3.2. Use of Tntlrrnel/a as a screenine model to detect drue activitv for parasitic "tissue" nematodes Fifteen applications were received to carry out a high-throughput, single mouse per compound assay screening using the Tichinella model, and one proposal was accepted for funding. This will be compared with the antifilarialin yivo screening model for approximately two years to see if any correlation of activity is seen. 3.3. In vitro screenins The lack of a good in vilro model for onchocerciasis and filariasis is detrimental to screening of compounds available only in small quantities. At present only the adult Onchocerca assays (using adult worms from cattle or humans) are available, and these are labour intensive and provide only small numbers of worms for assay. No responses were received from an advertisement to adapt the published method for rn virro cultivation of Brugia malayi for drug screening. 3.4. Drus testine in does and cattle B. pahangi in the dog has now been established as a reliable model and will allow the use of the B. malayi/leaf monkey model to be restricted to essential pharmacokinetic studies utilizing the human parasite B. malayi. Onchocerca gibsoni and O. ochengi in cattle will both be run using the same experimental compounds for a limited period to establish their usefulness as predictors of activity against O. volvulus in man. 3.5. Contract laboratories In order to provide the increased quantities of compound required (25 g for a dog experiment; 250 g for a cattle experiment) for secondary or tertiary drug testing, it has becomi essential to utilize a contract synthetic chemistry laboratory (Ash Stevens, USA) to provide compounds in such amounts. Additionally, there has been the need to support additional laboratories for analysis (SRI International, USA) and formulation (Dr D. Flanagan, University of Iowa, USA) of these compounds as academic laboratories have been unwilling to undertake such routine work and cannot operate to Good Laboratory Practice (GLP) standards as required by regulatory authorities. 3.6. Drue screenine and develooment oathwav Following the SWG meeting of Macrofil drug discovery and development laboratories on 7-10 July 1992, a summary of the drug development pathway for potentially macrofilaricidal drugs was developed (see Appendix l). ocP/EACr4.3 Page 5 4. STRATEGIC RESEARCH AREAS 4.1. Potential resistance to ivermectin in onchocerciasis Support has been continued to Dr C.D. Johnson (NemaPharm, [nc., USA) to investigate the genetics of mutant forms of the free-living nematode Caenorhabditis elegans resistant to ivermectin. Funding has also been given to a laboratory collaborating with Dr Johnson (Dr L.F. Le Jambre, Australia) on the identification of the gene(s) responsible for ivermectin resistance. ln Dr Le Jambre's laboratory the gene(s) responsible for resistance in the parasitic gastrointestinal nematode I/aemonchus contortus are also being studied. The genomic DNA involved in ivermectin resistance in C. elegans has now been identified and its nucleotide sequence is being studied. Once this sequence is available then a homologous sequence will be sought in Onchocerca. Dr A. Plaisier of the Erasmus University, Rotterdam, Netherlands, is also collaborating with Dr Johnson to allow genetic information on the appearance of ivermectin resistance in nematodes to be entered in the ONCHOSIM computer model. It should be emphasized that all genetic information from these studies indicates that high- level resistance to ivermectin is an unusual event in nematodes. 4.2. Identification of ootential tareets for drus action As part of the programme to identify additional drug targets in filariae, to allow solicitation of further compounds from the pharmaceutical industry and elsewhere, the Macrofil Project is supporting strategic research in the following biochemical areas. 4.2.1. Cysteine proteases (Dr J. McKerrow, University of California, San Francisco, USA). 4.2.2. Transcuticular transport (Professor J. Bennett, Michigan State University, USA). 4.2.3. Surface phosphorylcholineglycans (Dr W. Harnett, University of Strathclyde, United Kingdom). 4.2.4. Transglutaminases (Professor K. Mehta, University of Texas, USA). 4.2.5. Glutathione peroxidase (Dr M. Selkirk, Imperial College, London, United Kingdom) 4.2.6. Ecosanoids (Professor P. lrVeller, Beth Israel Hospital, Boston, USA) 4.2.7. Nuclear hormone receptors (Dr G. Ruvkun, Massachusetts General Hospital, Boston, usA). 5. ADMINSTRATION AND FINANCE The Macrofil Chemotherapy Project has now become established as a joint OCP/TDR Steering Committee, and TDR is contributing US$420 000 per annum during its 1992-93 biennium, while OCP will contribute an increased sum as agreed by JPC.l3 in 1992. During 1993 TDR has undergone a review of its scientific and administrative structures, and this has led to the proposal to radically change the administrative structures. Disease-specific programmes are generally being discarded, and one result is that the Filariasis Steering Committee will no longer exist after 1993. ocP/EAcr4.3 Page 6 Within TDR the Macrofil Project is unchanged, and will be sited within the Product Development Unit (PDU). As well as continuing joint development projects with PDU (e.g. UMF 078) there will also be closer collaboration with the other two Steering Committees which undertake drug development, i.e. malaria and trypanosomiasis/leishmaniasis. A small meeting was held recently (28-29 January 1993) which identified biochemical targets common to the three parasitic diseases of current interest to TDR. This will allow focusing of future strategic research and drug procurement in these areas. 6, APPENDICES In addition to Appendix I noted above, two further appendices give details of the research projects currently funded by the Macrofil Project (Appendix 2), and the current members of the Macrofil Steering Committee (Appendix 3). APPENDIX 1 Drug screening and developrnenE pathway New Assay? Irract- Active Irract. Active 1 aIII a II IJ ocP/EACL4.3 page 7 Active New Assay? Irracl. Active --1 , I) lrract. Active -?r''---2r'---- Inact. Act. Act. vt, B.v vs A. lnact Active Inact. TEST COI\IPOUNDS IN VITRO oNcflo (human) IN VITRO ONCTIO (bovine) JIRD ASSAY A. viteoc B. pahongi ONCIIO IN CATTLE B.p. lN DOG PRECLINICAL DEVELOPllt EN.T CLINICAL EVALUA'I'ION .SCHEME I Reject Accept w C.C , Oct. 1992 APPENDIX 2 UACROFIL CHEI.TOTHERAPY PROJECT - PROJECT FIINDING IN 1992 OCP PROJECT FI]NDING Proiect Institute and P.I Proiect title Fundins 9 10ss8 ocP/EACL4.3 page 8 85006 89009 9200s 88005 89003 92003 89010 92079L 9200L ussNo National Eye Centre Kaduna, Nigeria(Professor A. Abiose) Onchocerc ias is Chemotherapy Research Centre, Hohoe, Ghana(Dr K. Awadzi) University of Tennessee Knoxville, TN, USA(Professor D. Baker) Ash Stevens, Inc. DetroiE, MI, USA(Dr P. Bluurbergs) Be rrrtrard - Nocht - Ins t i tute Hanburg, Germany(Professor D. Btittner) Jemes Cook University Townsville, Australia(Professor D. Copeman) River Blindness Foundation, Lancaster United Kingdom(Dr B. Duke) University of Liverpool Liverpool United Kingdom(Dr G. Edwards) University of Iowa Iowa City, Iowa, USA(Professor D. Flanagan) University of Strathclyde Glasgow, United Kingdon(Dr W. Harnett) Field evaluation of computerized visual functions tests for onchocerciasls Clinical trials of drugs for onchocerciasis Resynthesis and evaluation of anti- filarial lead compounds Reslmthesis of potential antif ilarial compounds Bovlne screen for O. gibsoni Bllnd histopacho- logical evaluation of Onchocerca nodules following drug therapy In vitro and in vivo 111 250 drug tests of adult and larval O. volvuTus and electron microscopic study of drug effects 4 46L 206 555 72 073 L28 930 91 500 10 280 The effect of albendazo 1e/ ivermec t in combined in onchocerciasis s L26 Formulatlon of UMF 078 11 250 (total and UMF 289 22 5OO 502 wittr TDR) Phosphorylchollne- 38 353 glycan structures of (L2L 867) filarial parasites as a target for chemotherapy Subtotal 679 788 ocPlEAC14. 3 page 9 Appendix 2 Project titleProiect Institute and P.I 92007 University of Strathclyde Glasgow, United Kingdom(Dr trl. Harnett) SRI International Menlo Park, CA, USA(Dr P. Lim) University of Georgia Athens, GA, USA(Professor J. McCall) University of California San Francisco, CA, USA(Dr J. McKerrow) Assay of circulating antigens from Onchocerca spp. to detect macrofilaricidal activity Analysis of llMF 078 and llMF 289 Antifilarial drug evaluation in dogs Cysteine proteases in filariae us$No Funding 7 576(ts 000) 920790 88013 910540 92002 92006 89001 890t2 92004 Centre for Drug Research Kuala Lumpur, Malaysia(Prof. V. Navaratnan) PharnacokineEics of antifilarial drugs 5 000 (total 12 000 502 wittr TDR) L32 044 86 6L4 L29 455 47 500 l_81 230 103 589(f67 s40) L0 259 704 277 679 788 University of Virginia Charlottesville Virginia, USA(Prof. R. Sundberg) CABI Institute of Parasitology, St Albans Herts, United Kingdom(Dr S. Townson) CABI Institute of Parasitology, St Albans Herts, United Kingdon(Dr S. Townson) Dr R.D. Westland Thornoaks Drive Ann Arbor, MI, USA Synthesis of anti- filarial compounds Experimental chemo- therapy and screening of drugs against Onchocerca in vitro Discovery and development of new antifilarial drugs in vitro FeasibiliEy study on a conputerized data- handling system for use by the Macrofil Chemotherapy Project Subtotal Subtotal page 1 OCP TOTAL FIINDING 1 384 065 ocPlEAC14. 3 page 10 Appendix 2 TDR/Fllarlasls (FfL\ prolect fundlng Project Institute and P.I. Project title No. 910337 uEs 9L0574 920549 & 9208 11 910334 9t0332 920607 9103 33 920580 NemaPharm, Inc. Modelllng ivermectin Caurbridge, MA, USA resistance in Erasmus University O. voTvuTus Rotterdam, Netherlands(Drs C. Johnson & A. Plaisier) Mus6un National d'Histoire Naturelle Paris, France(Dr O. Bain) Michigan State University, East Lansing, MI, USA(Prof. J. Bennett) Institute for Medical Research, Kuala Lumpur Malaysia(Dr J.W. Mak) University of Georgia Athens, GA, USA(Prof. J. McCaIl) University of Texas Houston, TX, USA(Prof. K. Mehta) University of Indonesia Jakarta, Indonesia(Prof. B. Ruknono) Imperial College of Science, Technology & Medicine, London, UK(Dr M.E. Selkirk) Utilisation du nodEle ir nicrofilaires dermiques tI. martini pour 1'6tude des pathologies oculaires et lymphatiqes de 1' onchocercose hrrnaine et pour les essais th6rapeutiques Transcuticular transport in D. inmitis and Onchocerca spp: potential target for drug design Antifilarial drug testing in vitro and in vivo Experimental cherno- therapy of filariasis and screening of filaricides Inhibition of trans- glutaminases in filariae Screening of potential filaricides against H. kalimantani in leaf monkeys Cuticular glutathione peroxidase in filariae Fundine 12 000 s3 482 15 000 20 000 87 228 53 285 75 450 99 188 subrotal (Frt) 425 634 Appendix 2 TDR/Product Development Unlt (PDU) proiect fundlnc Project Institute and P.I. Project title Funding No. USS 920790 SRI International Menlo Park, CA, USA(Dr P. Lim) University of Iowa Iowa City, Iowa, USA(Professor D. Flanagan) , Analysis of IJMF 078 and IIMF 289 Formulation of UMF 078 and LIMF 289 ocPlEAC14.3 page 11 6 000 (cotal l_2 000 502 \trith ocP) 11 250 (total 22 500 502 wittr ocP) 92079L Subtotal (PDU) L7 250 Subtotal (FIL) 425 634 TDR TOTAL FI'NDING 442 884 tocPlEAC14.3 page L2 APPENDIX 3 UACROFIL CHEUOTHERAPY PROJECT STEERING COUI,IITTEE Llst of nenbers Professor (Mrs) A. Abiose, Medical Dlrector, The National Eye Centre, Off Express Bye-Pass, P.M.B. 2267, Kaduna, Nigeria Mr P. Acred, Chemotherapy Department, Glaxo Group Research Limited, Greenford Road, Greenford, Middlesex, UB5 OHE, United Kingdour (Chair) Dr W.C. Canpbell, Department of Biology, College of Liberal Arts, Drew University, Madison, New Jersey 07940-4037, USA Professor L.L. Fleckenstein, College of Pharmacy, 2269 Quadrangle Building,University of Iowa, Iowa City, Iowa 52242-LL23, USA Dr W.E. Gutteridge, Head, Antiparasite Chenotherapy Research, The Wellcome Research Laboratories, Langley Court, Beckenham, Kent, BR3 3BS, United Kingdom Dr G. JolIEs, Dlrecteur Scientifique, Rh6ne-Poulenc Rorer, 20 avenue Raymond-Aron, 92L65 Antony, France Professor V. Navaratnam, Director, Centre for Drug Research, Universiti Sains Malaysia, Minden Campus 11800, Penang, Malaysia Dr E.A. Ottesen, head, Clinical Parasitology Section, Building 4, National Institute of Allergy and Infectious Diseases, Maryland 20892, USA Room 126, PeEheeda, Coopted members Dr K. Awadzi, Director, Onchocerciasis Chemotherapy Research Centre, HohoeHospital, P.O. Box 144, Hohoe, Ghana Dr E.F. Elslager, Elslager Associates, 4081 Thornoaks Drive, Ann Arbor, Michigan 48104, USA (Chair, PDDT) Dr R. Engle, Chief, Department of Medicinal Chenistry, Division of Experimental Therapeutics, Walter Reed Army Instltute of Research, l^Iashington, D.C. 20307-5100, USA March 1993