Neglected tropical disease research and development

Last updated

Neglected tropical diseases (NTDs) are a set of infectious diseases affecting an estimated 1.4 billion people worldwide. The classification of this group of neglected diseases is linked to their frequent neglect in public and private sector expenditure and attention at local, national, and international levels, and their concentration among the poor. Research and development yielding safe, effective drugs and vaccines for their treatment and prevention has been recognized as a global health priority.

Contents

Overview

The structure of two of the ivermectins, an important class of drug in the control of Onchocerciasis. Ivermectin skeletal.svg
The structure of two of the ivermectins, an important class of drug in the control of Onchocerciasis.

Neglected tropical diseases are a set of infectious communicable diseases arising from a diverse group of parasitic worms, bacteria, and vector-borne protozoa. [1] The NTDs result in an estimated 534,000 deaths annually [2] and 57 million disability-adjusted life years (DALYs) lost. [3] The social, economic, and health burden of these diseases falls primarily on low and middle income countries where the diseases are most prevalent. [4] The NTDs represent the sixth greatest global health burden in terms of DALYs, equal to or potentially surpassing global malaria burden. [3] [5]

NTD interventions include both programs to address environmental and social determinants of health (e.g., vector control, water quality, sanitation), and programs offering mass drug administration for disease prevention and treatment. Drug treatments exist [6] to confront many of the NTDs and represent some of the world's essential medicines. [7] [8] Despite significant health and economic improvements using available medicines, [4] [9] [10] [11] the low number of new compounds being researched and developed for NTDs is an ongoing and significant challenge. [7] [12] [13] The dearth of candidates in pharmaceutical company drug pipelines is primarily attributed to the high costs of drug development and the fact that NTDs are concentrated among the world's poor. [12] [14] Other disincentives to investment include weak existing infrastructure for distribution and sales, and concerns regarding intellectual property protection. [11] However, the major stakeholders in NTD drug development—governments, foundations, pharmaceutical companies, academia, and NGOs—are involved in activities to help address the research and development shortfall and meet the many challenges presented by neglected tropical diseases. [15] Initiatives include public private partnerships, global R&D capacity building, priority vouchers to speed drug approval processes, open source scientific collaborations, and harmonization of global governance structures concerning NTDs.[ citation needed ]

NTD list

The diseases considered neglected tropical diseases vary. Malaria, HIV, and tuberculosis have received an amount of public attention and increased funding to no longer be considered neglected by some researchers. Outside "The Big Three", the seven most prevalent neglected tropical diseases in order of their global prevalence are ascariasis, trichuriasis, hookworm infection, schistosomiasis, lymphatic filariasis, and trachoma. [3] These seven are among a larger list of thirteen major NTDs: onchocerciasis, leishmaniasis, Chagas' disease, leprosy, Human African trypanosomiasis (sleeping sickness), Dracunculiasis, and Buruli ulcer. [3]

The World Health Organization's 2010 report dedicated to neglected tropical diseases offers an expanded list including dengue, rabies, yaws, cysticercosis, echinococcosis, and foodborne trematode infections. [16]

Neglected Tropical Diseases Worldwide Burden
DiseaseDALYs (million)Deaths/YrGlobal Prevalence (million)Population at Risk (million)
Schistosomiasis 4.5280,000207780
Hookworm 22.165,0005763200
Ascariasis 10.560,0008074200
Leishmaniasis 2.151,00012350
Trypanosomiasis 1.548,0000.360
Chagas disease 0.714,000825
Trichuriasis 6.410,0006043200
Leprosy 0.26,0000.4ND
Lymphatic filariasis 5.801201300
Trachoma 2.3084590
Onchocerciasis 0.503790
Cryptococcosis 12400,00018

ND=Not Determined [2] [3]

Deficient market

In their 2002 review of the U.S. Food and Drug Administration (FDA) databases and the European Agency for the Evaluation of Medicinal Products, Troullier et al found that 16 out of 1393 new chemical entities were approved for NTDs between 1975 and 1999 (~1%). [7] Cohen et al revisited the data and using the same methodology found 32 new chemical entities during the time period. [8] In a second analysis using an expanded list of NTDs based on the G-FINDER survey, [17] the number was slightly higher, with 46 new drugs and vaccines approved (~3% of the total including HIV drugs). [8] Between 2000 and 2009, there has been some increase with an additional 26 newly approved drugs and vaccines for NTDs. [8]

A number of factors are recognized as contributing to the low number. The barrier most reported is the high cost of drug development. Estimates are that pharmaceutical companies' development costs to approval fall between $500 million and $2 billion. [18] DiMasi, Hansen, and Grabowski calculated an average of $802 million in year 2000 dollars. [19] Furthermore, the time that drugs are approved for use averages seven years out of the twenty years on-patent, meaning a tendency for the market to focus on diseases of developed nations where high prices can be used to recoup research and development costs, and subsidize failed R&D efforts. In short, NTD research and development is considered a high investment risk given that NTDs predominantly affect the poor in low and middle income countries. [12] [14] Additional barriers include drug safety regulatory requirements, intellectual property protection problems, and poor infrastructure for distribution and sales. [11] [12]

Although drug companies have not invested heavily in the NTDs, in several cases, rather than focus on profits, some have decided to donate key drugs to address NTDs. For example, Merk has had a program since the mid-1980s to donate ivermectin (Mectizan) indefinitely to support the global fight of onchoceriasis. GlaxoSmithKline and several other large pharmaceutical companies have donation programs as well. Drug donation however, does not ameliorate the deficiency of new chemical entities being researched and developed. This is especially of concern with reports of emerging resistance among existing drugs. [20] [21]

Policy initiatives

Public private partnerships

Melinda and Bill Gates speak during press conference at the World Economic Forum in Davos, Switzerland, January 30, 2009. Remy Steinegger - World Economic Forum - Melinda French Gates, Bill Gates - World Economic Forum Annual Meeting Davos 2009 (by-sa).jpg
Melinda and Bill Gates speak during press conference at the World Economic Forum in Davos, Switzerland, January 30, 2009.

Governments, foundations, the non-profit sector, and private sector have found new connections to help address market deficiencies by providing funding support and spreading both the costs and risks of NTD research and development. The proliferation of public private partnerships (PPPs) has been recognized as a key innovation in the past decade, helping to unlock existing and new resources.[ citation needed ]

Major PPPs for NTDs include: the Sabin Vaccine Institute, Norvartis Vaccines Institute for Global Health, MSD Wellcome Trust Hilleman Laboratories, Infectious Diseases Research Institute, Institut Pasteur and INSERM, WIPO Re:Search, and the International Vaccine Institute. [14] Likewise, a number of new academic drug development centers have been created in recent years drawing in industry partners. Support for these centers is frequently traced to the Bill and Melinda Gates Foundation, the Sandler Foundation, and the Wellcome Trust. [22]

R&D capacity building in middle income countries

Growing NTD research and development capacity in middle income countries is an area of policy interest. A 2009 study of biotechnology companies in India, China, Brazil, and South Africa revealed sixty-two NTD products in development and on the market out of approximately five hundred products offered (~14%). When products to fight HIV, malaria, and TB were included in the analysis, the number increased to one hundred twenty-three products, approximately 25% of the total products offered.[ citation needed ]

Researchers have argued that unlike most multinationals, small and mid-sized "Global South" companies see significant business opportunities in the development of NTD-related diagnostics, biologics, pharmaceuticals, and services. [23] Potential actions to improve and expand this R&D capacity have been recommended including expansion of human capital, increased private investment, knowledge and patent sharing, infrastructure building for business incubation and innovation support.[ citation needed ]

Innovation prizes and grants

Competitive innovation prizes have been used to spur development in a range of fields such as aerospace engineering, clean technology, and genomics. The X-Prize Foundation is launching a competition for high speed, point-of-care diagnostics for tuberculosis.[ citation needed ] A more widely defined annual "Global Health EnterPrize" for neglected tropical diseases has been proposed to reward health innovators, particularly those based in countries where NTDs represent a serious health burden.[ citation needed ]

The Bill & Melinda Gates Foundation offers the Grand Challenges Explorations Opportunities on a rolling basis. This grant program allows individuals from any organization or background to apply to address priority global health issues. Each project award is $100,000 dollars and is drawn from a Foundation funding pool of $100 million. Awardees have tended to offer research projects on topics that are highly speculative but offer potentially game-changing breakthroughs in global health.

FDA priority review vouchers (PRV)

In 2006, Ridley et al recommended the development of a priority review voucher (PRV) in the journal Health Affairs . It gained interest by Senator Sam Brownback of Kansas who championed its introduction in the FDA Amendments Act of 2007. Under the enacted law, FDA approval of a non-NTD drug can be accelerated through the drug review process if paired to a drug that addresses a NTD. The potential economic benefit to a pharmaceutical company is estimated to be potentially as high as $300 million per drug. Three drugs have earned NTD PRVs to date (December 2014): Coartem (by Novartis, for malaria); bedaquiline (by Janssen, for TB) and miltefosine (by Knight, for leishmaniasis). However, the success of the PRV system is now under much scrutiny, given that Knight benefitted by $125 million from the sale of a PRV earned from a drug (miltefosine) that was largely researched and developed by the WHO. Medicins San Frontiers are now pressuring Knight to guarantee supplying miltefosine at cost price, thus far without success.

The PRV isn't limited to the pairing of drugs within a single company, rather can be transferred between companies. Companies with NTD drug candidates in their pipelines but without a blockbuster drug, are able to sell their voucher producing financial returns. In the EU, similar priority review incentives are now under consideration to increase the speed of regulatory pricing and reimbursement decisions.

However, PRVs have been criticized as being open to manipulation and possibly encouraging errors through too rapid regulatory decision-making. [24]

Open source collaboration initiatives

The Drugs for Neglected Diseases Initiative, a web focused not-for-profit drug R&D organization dedicated to creating new NTD treatments. DNDi logo.JPG
The Drugs for Neglected Diseases Initiative, a web focused not-for-profit drug R&D organization dedicated to creating new NTD treatments.

Several companies and scientific organizations are participating in open source initiatives to share drug data and patent information over the web, and facilitate virtual collaboration on NTD research.

One rich area to explore is in the wealth of genomic data resulting from the sequencing of parasite genomes. These data offer opportunities for the exploration of new therapeutic products using computational, and open source collaboration methods for drug discovery. [25] [26] The Tropical Disease Initiative, for example, has used large amounts of computing power to generate the protein structures for ten parasite genomes. An open source drug bank was matched algorithmically to determine compounds with protein interaction activity, and two candidates were identified. In general, such methods may hold important opportunities for off-label use of existing approved drugs.

Related Research Articles

Chagas disease Human infectious disease

Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by Trypanosoma cruzi. It is spread mostly by insects in the subfamily Triatominae, known as "kissing bugs". The symptoms change over the course of the infection. In the early stage, symptoms are typically either not present or mild, and may include fever, swollen lymph nodes, headaches, or swelling at the site of the bite. After four to eight weeks, untreated individuals enter the chronic phase of disease, which in most cases does not result in further symptoms. Up to 45% of people with chronic infection develop heart disease 10–30 years after the initial illness, which can lead to heart failure. Digestive complications, including an enlarged esophagus or an enlarged colon, may also occur in up to 21% of people, and up to 10% of people may experience nerve damage.

Onchocerciasis Human helminthiasis (infection by parasite)

Onchocerciasis, also known as river blindness, is a disease caused by infection with the parasitic worm Onchocerca volvulus. Symptoms include severe itching, bumps under the skin, and blindness. It is the second-most common cause of blindness due to infection, after trachoma.

Scrub typhus Disease caused by O. tsutsugamushi

Scrub typhus or bush typhus is a form of typhus caused by the intracellular parasite Orientia tsutsugamushi, a Gram-negative α-proteobacterium of family Rickettsiaceae first isolated and identified in 1930 in Japan.

Cysticercosis Tissue infection caused by the young form of the pork tapeworm

Cysticercosis is a tissue infection caused by the young form of the pork tapeworm. People may have few or no symptoms for years. In some cases, particularly in Asia, solid lumps of between one and two centimetres may develop under the skin. After months or years these lumps can become painful and swollen and then resolve. A specific form called neurocysticercosis, which affects the brain, can cause neurological symptoms. In developing countries this is one of the most common causes of seizures.

Helminthiasis Any macroparasitic disease caused by helminths

Helminthiasis, also known as worm infection, is any macroparasitic disease of humans and other animals in which a part of the body is infected with parasitic worms, known as helminths. There are numerous species of these parasites, which are broadly classified into tapeworms, flukes, and roundworms. They often live in the gastrointestinal tract of their hosts, but they may also burrow into other organs, where they induce physiological damage.

Tropical medicine Interdisciplinary branch of medicine

Tropical medicine is an interdisciplinary branch of medicine that deals with health issues that occur uniquely, are more widespread, or are more difficult to control in tropical and subtropical regions.

Hookworm infection Human disease caused by infection by intestinal parasites of the roundworm group

Hookworm infection is an infection by a type of intestinal parasite known as a hookworm. Initially, itching and a rash may occur at the site of infection. Those only affected by a few worms may show no symptoms. Those infected by many worms may experience abdominal pain, diarrhea, weight loss, and tiredness. The mental and physical development of children may be affected. Anemia may result.

The soil-transmitted helminths are a group of intestinal parasites belonging to the phylum Nematoda that are transmitted primarily through contaminated soil. They are so called because they have a direct life cycle which requires no intermediate hosts or vectors, and the parasitic infection occurs through faecal contamination of soil, foodstuffs and water supplies. The adult forms are essentially parasites of humans, causing soil-transmitted helminthiasis (STH), but also infect domesticated mammals. The juveniles are the infective forms and they undergo tissue-migratory stages during which they invade vital organs such as lungs and liver. Thus the disease manifestations can be both local and systemic. The geohelminths together present an enormous infection burden on humanity, amounting to 135,000 deaths every year, and persistent infection of more than two billion people.

Neglected tropical diseases Diverse group of tropical infection diseases which are common in developing countries

Neglected tropical diseases (NTDs) are a diverse group of tropical infections which are common in low-income populations in developing regions of Africa, Asia, and the Americas. They are caused by a variety of pathogens such as viruses, bacteria, protozoa and parasitic worms (helminths). These diseases are contrasted with the big three infectious diseases, which generally receive greater treatment and research funding. In sub-Saharan Africa, the effect of these diseases as a group is comparable to malaria and tuberculosis. NTD co-infection can also make HIV/AIDS and tuberculosis more deadly.

Peter Hotez

Peter Jay Hotez is an American scientist, pediatrician, and advocate in the fields of global health, vaccinology, and neglected tropical disease control. He serves as founding dean of the National School of Tropical Medicine, Professor of Pediatrics and Molecular Virology & Microbiology at Baylor College of Medicine, where he is also Director of the Texas Children's Hospital Center for Vaccine Development and Texas Children's Hospital Endowed Chair in Tropical Pediatrics, and University Professor of Biology at Baylor University. Hotez served previously as president of the American Society of Tropical Medicine and Hygiene and is a founding Editor-in-Chief of PLOS Neglected Tropical Diseases. He is also the co-director of Parasites Without Borders, a global nonprofit organization with a focus on those suffering from parasitic diseases in subtropical environments.

Hookworm vaccine

Hookworm vaccine is a vaccine against hookworm. No effective vaccine for the disease in humans has yet been developed. Hookworms, parasitic nematodes transmitted in soil, infect approximately 700 million humans, particularly in tropical regions of the world where endemic hookworms include Ancylostoma duodenale and Necator americanus. Hookworms feed on blood and those infected with hookworms may suffer from chronic anaemia and malnutrition. Helminth infection can be effectively treated with benzimidazole drugs, and efforts led by the World Health Organization have focused on one to three yearly de-worming doses in schools because hookworm infections with the heaviest intensities are most common in school-age children. However, these drugs only eliminate existing adult parasites and re-infection can occur soon after treatment. School-based de-worming efforts do not treat adults or pre-school children and concerns exist about drug resistance developing in hookworms against the commonly used treatments, thus a vaccine against hookworm disease is sought to provide more permanent resistance to infection.

Intermittent preventive therapy or intermittent preventive treatment (IPT) is a public health intervention aimed at treating and preventing malaria episodes in infants (IPTi), children (IPTc), schoolchildren (IPTsc) and pregnant women (IPTp). The intervention builds on two tested malaria control strategies to clear existing parasites and to prevent new infections (prophylaxis).

Chagas: Time to Treat campaign

The Chagas: Time to Treat Campaign is an international campaign started by the Drugs for Neglected Diseases initiative to advocate for increased research and development of treatments for Chagas disease. Chagas is a potentially fatal neglected disease that affects between 8 and 13 million people worldwide. DNDi's Time to Treat campaign is pushing for increased political interest in new treatments for Chagas disease, increased public awareness of the disease and treatment limitations and increased public and private investment in R&D.

Soil-transmitted helminthiasis Type of helminth infection caused by different species of roundworms

Soil-transmitted helminthiasis is a type of helminth infection (helminthiasis) caused by different species of roundworms. It is caused specifically by those worms which are transmitted through soil contaminated with faecal matter and are therefore called soil-transmitted helminths. Three types of soil-transmitted helminthiasis can be distinguished: ascariasis, hookworm infection and whipworm infection. These three types of infection are therefore caused by the large roundworm A. lumbricoides, the hookworms Necator americanus or Ancylostoma duodenale and by the whipworm Trichuris trichiura.

Children Without Worms (CWW) is a program of the Task Force for Global Health and envisions a world in which all at-risk people are healthy and free of intestinal worms so they can develop to their full potential. To accomplish the vision of a worm-free world, CWW works closely with the World Health Organization, national Ministries of Health, nongovernmental organizations and private-public coalitions such as Uniting to Combat NTDs.

Mundo Sano, or Fundación Mundo Sano, is a scientific, nongovernmental foundation in Argentina working for the prevention and control of communicable diseases such as dengue fever, Chagas disease, malaria, leishmaniasis and soil-transmitted helminthiasis. Its main objective is to facilitate equal access to health and welfare among people who are vulnerable to these otherwise avoidable diseases, mainly by promoting strategic policies for the improvement of the quality of life of affected communities.

Sabin Vaccine Institute (Sabin), located in Washington, D.C., is a nonprofit organization promoting global vaccine development, availability, and use. Through its work, Sabin hopes to reduce human suffering by preventing the spread of vaccine-preventable, communicable disease in humans through herd immunity and mitigating the poverty caused by these diseases.

Oluwatoyin (Toyin) Asojo is Associate Professor and chair of the Department of Chemistry and Biochemistry at Hampton University. She was formerly an Associate Professor of Pediatrics-Tropical medicine at the Baylor College of Medicine. She works at "the interface of math, chemistry, biology, computation." She is a crystallographer and interested in structural studies of proteins from neglected tropical disease pathogens.

World NTD Day is an awareness day for addressing neglected tropical diseases (NTDs).

David Molyneux British parasitologist

David Hurst Molyneux CMG is a British parasitologist who served as the Director of the Liverpool School of Tropical Medicine (1991–2000), where, as of 2018, he is an emeritus professor. He previously held the Chair of Biological Sciences at the University of Salford (1977–91), where he also served as Dean of the Faculty of Science. His research and advocacy have focused on what are now known as neglected tropical diseases, and Michael Barrett credits him as among the earliest advocates of the campaign to focus international attention on this group of diseases in the early-to-mid 2000s.

References

  1. ↑ Feasey N, Wansbrough-Jones M, Mabey DC, Solomon AW. Neglected tropical diseases. Br Med Bull. 2010;93:179-200. Epub 2009 Dec 10. Review.
  2. 1 2 Hotez PJ, Molyneux DH, Fenwick A, Ottesen E, Ehrlich Sachs S, Sachs JD. Incorporating a rapid-impact package for neglected tropical diseases with programs for HIV/AIDS, tuberculosis, and malaria. PLoS Med 2006 Jan;3(5):e102.
  3. 1 2 3 4 5 Hotez PJ, Molyneux DH, Fenwick A, Kumaresan J, Sachs SE, Sachs JD, et al. Control of neglected tropical diseases. N Engl J Med 2007 Sep 6;357(10):1018-1027.
  4. 1 2 Conteh L, Engels T, Molyneux DH. Socioeconomic aspects of neglected tropical diseases. Lancet 2010 Jan 16;375(9710):239-247.
  5. ↑ Hotez P, Ottesen E, Fenwick A, Molyneux D. The neglected tropical diseases: the ancient afflictions of stigma and poverty and the prospects for their control and elimination. Adv Exp Med Biol 2006;582:23-33.
  6. ↑ Reddy M, Gill SS, Kalkar SR, Wu W, Anderson PJ, Rochon PA. Oral drug therapy for multiple neglected tropical diseases: a systematic review. JAMA 2007 Oct 24;298(16):1911-1924.
  7. 1 2 3 Trouiller P, Olliaro P, Torreele E, Orbinski J, Laing R, Ford N. Drug development for neglected diseases: a deficient market and a public-health policy failure. Lancet 2002 Jun 22;359(9324):2188-2194.
  8. 1 2 3 4 Cohen J, Dibner MS, Wilson A. Development of and access to products for neglected diseases. PLoS One 2010 May 12;5(5):e10610.
  9. ↑ Chu BK, Hooper PJ, Bradley MH, McFarland DA, Ottesen EA. The economic benefits resulting from the first 8 years of the Global Programme to Eliminate Lymphatic Filariasis (2000-2007). PLoS Negl Trop Dis. 2010 Jun 1;4(6):e708.
  10. ↑ Merck Mectizan Drug Donation Program http://www.mectizan.org/
  11. 1 2 3 Villa S, Compagni A, Reich MR. Orphan drug legislation: lessons for neglected tropical diseases. Int J Health Plann Manage 2009 Jan-Mar;24(1):27-42.
  12. 1 2 3 4 Trouiller P, Torreele E, Olliaro P, White N, Foster S, Wirth D, et al. Drugs for neglected diseases: a failure of the market and a public health failure? Trop Med Int Health 2001 Nov;6(11):945-951.
  13. ↑ Chirac P, Torreele E. Global framework on essential health R&D. Lancet. 2006 May 13;367(9522):1560-1.
  14. 1 2 3 Bethony JM, Cole RN, Guo X, Kamhawi S, Lightowlers MW, Loukas A, et al. Vaccines to combat the neglected tropical diseases. Immunol Rev 2011 Jan;239(1):237-270.
  15. ↑ Liese B, Rosenberg M, Schratz A. Programmes, partnerships, and governance for elimination and control of neglected tropical diseases. Lancet 2010 Jan 2;375(9708):67-76.
  16. ↑ World Health Organization. Working to overcome the global impact of neglected tropical diseases: first WHO report on neglected tropical diseases. 2010.
  17. ↑ G-FINDER Database http://www.georgeinstitute.org/about-us/media-centre/g-finder-database-open-public
  18. ↑ Adams CP, Brantner VV. Estimating the cost of new drug development: is it really 802 million dollars? Health Aff (Millwood). 2006 Mar-Apr;25(2):420-8.
  19. ↑ DiMasi JA, Hansen RW, Grabowski HG. The price of innovation: new estimates of drug development costs. J Health Econ. 2003 Mar;22(2):151-85.
  20. ↑ Tchuem Tchuente LA. Control of soil-transmitted helminths in sub-Saharan Africa: Diagnosis, drug efficacy concerns and challenges. Acta Trop 2010 Jul 21.
  21. ↑ Smits HL. Prospects for the control of neglected tropical diseases by mass drug administration. Expert Rev Anti Infect Ther 2009 Feb;7(1):37-56.
  22. ↑ Renslo AR, McKerrow JH. Drug discovery and development for neglected parasitic diseases. Nat Chem Biol 2006 Dec;2(12):701-710.
  23. ↑ Frew SE, Liu VY, Singer PA. A business plan to help the 'global South' in its fight against neglected diseases. Health Aff (Millwood) 2009 Nov-Dec;28(6):1760-1773.
  24. ↑ Kesselheim AS. Drug development for neglected diseases - the trouble with FDA review vouchers. N Engl J Med 2008 Nov 6;359(19):1981-1983.
  25. ↑ Kar S. Opinion: Open innovation: an answer for neglected diseases. Future Med Chem 2010 Sep;2(9):1411-5.
  26. ↑ Ortí L, Carbajo RJ, Pieper U, Eswar N, Maurer SM, Rai AK, Taylor G, Todd MH, Pineda-Lucena A, Sali A, Marti-Renom MA. A kernel for open source drug discovery in tropical diseases. PLoS Negl Trop Dis 2009;3(4):e418.

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.