Cancer vaccines

The prevention and eradication of smallpox: a commentary on Sloane (1755) 'An account of inoculation'

Sir Hans Sloane's account of inoculation as a means to protect against smallpox followed several earlier articles published in Philosophical Transactions on this procedure. Inoculation (also called 'variolation') involved the introduction of small amounts of infectious material from smallpox vesicles into the skin of healthy subjects, with the goal of inducing mild symptoms that would result in protection against the more severe naturally acquired disease. It began to be practised in England in 1721 thanks to the efforts of Lady Mary Wortley Montagu who influenced Sloane to promote its use, including the inoculation of the royal family's children. When Edward Jenner's inoculation with the cow pox ('vaccination') followed 75 years later as a safer yet equally effective procedure, the scene was set for the eventual control of smallpox epidemics culminating in the worldwide eradication of smallpox in 1977, officially proclaimed by WHO in 1980. Here, we discuss the significance of variolation and vaccination with respect to scientific, public health and ethical controversies concerning these 'weapons of mass protection'. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society.

Cross-sectional and longitudinal analysis of cancer vaccination trials registered on the US Clinical Trials Database demonstrates paucity of immunological trial endpoints and decline in registration since 2008

Introduction

Cancer vaccination has been researched as a means of treating and preventing cancer, but successful translational efforts yielding clinical therapeutics have been limited. Numerous reasons have been offered in explanation, pertaining both to the vaccine formulation, and the clinical trial methodology used. This study aims to characterize the tumor vaccine clinical trial landscape quantitatively, and explore the possible validity of the offered explanations including the translational obstacles posed by the current common endpoints.

Methods

We performed a detailed cross-sectional and longitudinal analysis of tumor vaccine trials (n=955) registered in the US Clinical Trials database.

Results

The number of tumor vaccine trials initiated per annum has declined 30% since a peak in 2008. In terms of vaccine formulation, 25% of trials use tumor cell/lysate preparations; whereas, 73% of trials vaccinate subjects against defined protein/peptide antigens. Also, 68% of trials do not use vectors for antigen delivery. Both these characteristics of tumor vaccines have remained unchanged since 1996. The top five types of cancer studied are: melanoma (22.6%); cervical cancer (13.0%); breast cancer (11.3%); lung cancer (9.5%); and prostate cancer (9.4%). In addition, 86% of the trials are performed where there is established disease rather than prophylactically, of which 67% are performed exclusively in the adjuvant setting. Also, 42% of Phase II trials do not measure any survival-related endpoint, and only 23% of Phase III trials assess the immune response to vaccination.

Conclusion

The clinical trial effort in tumor vaccination is declining, necessitating a greater urgency in identifying and removing the obstacles to clinical translation. These obstacles may include: 1) vaccination against a small range of antigens; 2) naked delivery of antigen; 3) investigation of less immunogenic cancer types; and 4) investigation in the setting of established disease. In addition, the prevalence of late phase failure may be due to inadequate assessment of survival-related endpoints in Phase II trials. The clinical trial development of tumor vaccines should include mechanism-based translational endpoints, as well as the discovery of immune biomarkers with which to stratify, monitor, and prognosticate patients.

Placenta-derived gp96 as a multivalent prophylactic cancer vaccine

A major challenge for designing prophylactic cancer vaccines is to define immunogenic and safe cancer antigens. Given the striking similarity of antigen expression patterns between cancer and embryonic tissues, we defined a prototype strategy of using placenta-derived heat shock protein gp96, which induces prophylactic anti-tumor T cell responses. Immunization with placental gp96 provided partial protection and long-term (at least 3 months) anti-tumor immunity against growth of transplantable melanoma or breast tumors in mice, elicited total protection against 7, 12-dimethylbenz(a)-anthracene (DMBA)-induced mammary tumors in rats, and significantly reduced the occurrence and growth of autochthonous breast tumors in HER2 transgenic mice. Placental gp96 activated HER2- and MUC1-specific T cell responses through binding to tumor-associated antigens. Our results reveal the novel immunogenicity of placental gp96 and its potential use as a multivalent cancer vaccine.

The contribution of vaccination to global health: past, present and future

Vaccination has made an enormous contribution to global health. Two major infections, smallpox and rinderpest, have been eradicated. Global coverage of vaccination against many important infectious diseases of childhood has been enhanced dramatically since the creation of WHO's Expanded Programme of Immunization in 1974 and of the Global Alliance for Vaccination and Immunization in 2000. Polio has almost been eradicated and success in controlling measles makes this infection another potential target for eradication. Despite these successes, approximately 6.6 million children still die each year and about a half of these deaths are caused by infections, including pneumonia and diarrhoea, which could be prevented by vaccination. Enhanced deployment of recently developed pneumococcal conjugate and rotavirus vaccines should, therefore, result in a further decline in childhood mortality. Development of vaccines against more complex infections, such as malaria, tuberculosis and HIV, has been challenging and achievements so far have been modest. Final success against these infections may require combination vaccinations, each component stimulating a different arm of the immune system. In the longer term, vaccines are likely to be used to prevent or modulate the course of some non-infectious diseases. Progress has already been made with therapeutic cancer vaccines and future potential targets include addiction, diabetes, hypertension and Alzheimer's disease.

Production of recombinant immunotherapeutics for anticancer treatment: the role of bioengineering

Cancer is one of the most important health problems because many cases are difficult to prevent. Cancer still has unknown mechanisms of pathogenesis, and its capacity to produce temporary or permanent damage, besides death, is very high. Although many anticancer therapies are available, finding a cure for cancer continues to be a difficult task. Thus, many efforts have been made to develop more effective treatments, such as immunotherapy based on a new class of tumor-specific products that are produced using recombinant DNA technology. These recombinant products are used with the main objectives of killing the tumor and stimulating immune cells to respond to the cancer cells. The principal recombinant products in anticancer therapy are immunostimulants, vaccines, antibodies, immunotoxins and fusion proteins. This review focuses on the general aspects of these genetically engineered products, their clinical performance, current advances and future prospects for this type of anticancer therapy.

Twenty-first century vaccines

In the twentieth century, vaccination has been possibly the greatest revolution in health. Together with hygiene and antibiotics, vaccination led to the elimination of many childhood infectious diseases and contributed to the increase in disability-free life expectancy that in Western societies rose from 50 to 78-85 years (Crimmins, E. M. & Finch, C. E. 2006 Proc. Natl Acad. Sci. USA 103, 498-503; Kirkwood, T. B. 2008 Nat. Med 10, 1177-1185). In the twenty-first century, vaccination will be expected to eliminate the remaining childhood infectious diseases, such as meningococcal meningitis, respiratory syncytial virus, group A streptococcus, and will address the health challenges of this century such as those associated with ageing, antibiotic resistance, emerging infectious diseases and poverty. However, for this to happen, we need to increase the public trust in vaccination so that vaccines can be perceived as the best insurance against most diseases across all ages.

Vaccines and global health

Vaccines have made a major contribution to global health in recent decades but they could do much more. In November 2011, a Royal Society discussion meeting, 'New vaccines for global health', was held in London to discuss the past contribution of vaccines to global health and to consider what more could be expected in the future. Papers presented at the meeting reviewed recent successes in the deployment of vaccines against major infections of childhood and the challenges faced in developing vaccines against some of the world's remaining major infectious diseases such as human immunodeficiency virus (HIV), malaria and tuberculosis. The important contribution that development of more effective veterinary vaccines could make to global health was also addressed. Some of the social and financial challenges to the development and deployment of new vaccines were reviewed. The latter issues were also discussed at a subsequent satellite meeting, 'Accelerating vaccine development', held at the Kavli Royal Society International Centre. Delegates at this meeting considered challenges to the more rapid development and deployment of both human and veterinary vaccines and how these might be addressed. Papers based on presentations at the discussion meeting and a summary of the main conclusions of the satellite meeting are included in this issue of Philosophical Transactions of the Royal Society B.