07/15/2025  |  Aline Tavares

https://butantan.gov.br/noticias/ensaios-clinicos-no-butantan-%7C-das-laranjas-a-variola-a-evolucao-da-pesquisa-clinica-no-butantan-e-no-mundo 

Research on humans has been conducted since the 18th century, but it was only regulated in the 20th century. Learn how Butantan has kept pace with these advances.

The series “Clinical Trials at Butantan” provides an overview of clinical studies and how the Butantan Institute has evolved in this area, becoming one of the largest vaccine developers in Latin America.
 
The Butantan Institute began its journey in the development of serums and vaccines more than a century ago, in the midst of the bubonic plague epidemic of 1899, and today it is consolidated as one of the largest producers of immunobiologicals in Latin America. A fundamental part of this work involves conducting clinical studies, research on humans that allows the safety and efficacy of new immunizers and drugs to be evaluated. Over its 124 years, Butantan has been responsible for more than 30 clinical trials, including the largest study ever conducted in the country (on the dengue vaccine), and is preparing to respond to future pandemics. This maturity is due not only to the Institute's own advances, but also to the lessons learned by science as a whole.

To contextualize the history of clinical studies, we need to go back in time: the first pharmaceutical tests on humans in the world date back to 1747, when Scottish physician James Lind attempted to investigate a cure for scurvy. The disease affected sailors and caused bruising, anemia, and excessive fatigue. By administering different substances to patients—diluted sulfuric acid, vinegar, and citrus fruits—Lind discovered that fruits improved the condition. Scientists at the time did not know that the disease was caused by a lack of vitamin C, and the inclusion of lemons and oranges in the sailors' diet solved the problem.

A few years later, in 1796, the world's first vaccine, for smallpox, appeared. The disease was one of the most feared at the time, with a mortality rate of up to 50%. While studying it, English physician Edward Jenner noticed that rural residents (who milked cows) who had contracted cowpox were not infected by the human virus. So he conducted an experiment: he applied a small dose of the bovine virus to an eight-year-old boy named James Phipps, who developed a milder form of the disease and recovered. Jenner then introduced the human smallpox virus to the boy, who did not become ill because he was already immune. Smallpox is estimated to have caused 300 million deaths globally.

Other milestones in clinical studies would occur in the following century: in 1863, when American physician Austin Flint conducted the first study comparing a “fictitious medicine” made from herbal extracts (placebo) to an active treatment in 13 patients with rheumatism; and in 1885, when French scientist Louis Pasteur successfully tested a rabies vaccine on a 9-year-old boy who had been bitten by an infected dog.

But it was only in the second half of the 20th century that studies in humans began to be regulated, following international criteria to ensure the safety of participants. Today, for example, it would be unthinkable to evaluate a new vaccine candidate in a child without first testing it in a healthy adult population. The practice was necessary in the past due to the urgency of combating serious and fatal diseases, especially in children, but today it would raise ethical and regulatory issues.

In Brazil, the regulatory framework began in 1999 with the creation of the National Health Surveillance Agency (Anvisa), responsible for overseeing products and services related to public health. As these processes were established in the country, the Butantan Institute, which already had a tradition in the production of vaccines and serums, began to develop its first clinical trials in 2003.

Learn more about how clinical development at Butantan—and around the world—evolved to give rise to a chain of extremely solid and rigorous processes that are followed by the entire pharmaceutical industry.

First half of the 20th century: the discovery of serotherapy

The 20th century was marked by exponential growth in science and medicine and the emergence of several research institutions and universities. The creation of the Butantan Institute was a result of this movement: the organization was founded in São Paulo in 1901, under the direction of public health expert Vital Brazil, to produce serum to combat an outbreak of bubonic plague, which was then spreading through the port of Santos. At the same time, in 1900, the Oswaldo Cruz Foundation (Fiocruz) was established in Rio de Janeiro with the same objective.

Serotherapy took its first steps at the turn of the 19th century. In the 1890s, German physician Emil von Behring and Japanese microbiologist Shibasaburo Kitasato demonstrated that serum from rabbits immunized with the toxin from the bacterium Clostridium tetani protected mice inoculated with the bacillus, leading to the neutralization of the tetanus toxin. The same was proven for diphtheria toxin. This finding resulted in the development of immunobiologicals made from horse plasma to cure various serious infectious diseases.

In Brazil, the manufacture of these products began with the anti-plague serum made by Butantan, based on Yersin's serum, developed at the Pasteur Institute in France. Within a few months, the disease was under control, and the Institute was able to devote itself to other public health issues. The efforts of the still young institution then turned to snake bites, a personal concern of Vital Brazil, which caused 5,000 deaths per year in the state of São Paulo alone.

Based on the studies of French bacteriologist Léon Calmette, creator of the first antivenom for snake bites, the founder of Butantan began to develop antivenom serums and discovered the specificity factor of these drugs – that is, that each species of snake required a different type of serum. He soon began to produce polyvalent serums that worked against different species, in case it was not possible to identify the animal that caused the accident. The serum was obtained from the blood of horses immunized with snake venom and tested first on animals before being administered to humans.

Although antivenom serums have not undergone modern clinical trials—which, in this case, would need to overcome the challenge of recruiting volunteers and the unpredictability and variability of snake accidents—the success and safety of the treatment have been proven in millions of cases throughout the century. No wonder the therapy is still used today and continues to undergo research to be improved. 

In 1906 and 1915, Butantan also began manufacturing anti-diphtheria and anti-tetanus serums. To this day, the Institute is one of the only manufacturers of anti-diphtheria serum in the world, exporting it to countries such as the United States, Canada, the United Kingdom, the Netherlands, Colombia, and the Dominican Republic.

Butantan's serum production chain has evolved in accordance with Anvisa regulations. Today, 600,000 vials are sent to the Ministry of Health every year to be distributed free of charge by the Unified Health System (SUS). During the production process, each serum undergoes more than 30 quality control tests. In addition, safety is constantly monitored by the Institute's Pharmacovigilance service, which monitors adverse events related to the institution's products.

Serums continue to be one of the focuses of Butantan's scientific research. A recent study published in PLOS Neglected Tropical Diseases analyzed 146 patients and concluded that anti-arachnid serum prevents skin necrosis in people bitten by brown spiders. Another study published in the scientific journal Toxicon describes the requirements for the application of serums in indigenous villages, aiming to increase access to antivenoms for indigenous and riverine populations. 

Second half of the 20th century: the regulation of clinical research 
The need to regulate clinical studies became a global concern after 1947, following World War II. With the Nuremberg Code, the world established principles for conducting research on human beings, prioritizing voluntary consent, safety, and benefits for the patient. These principles were complemented by the World Medical Association's Declaration of Helsinki in 1964.

Another significant factor that drove this regulation was the thalidomide tragedy in the 1950s and 60s. The drug was an anti-inflammatory commonly prescribed to relieve nausea and insomnia in pregnant women, which ended up causing an alarming increase in the number of cases of babies with congenital malformations. A total of 10,000 cases were reported in several countries, including Brazil, with a mortality rate of up to 40%.

The Food and Drug Administration (FDA), the US regulatory agency, did not approve the drug for sale due to a lack of safety evidence and data on adverse effects in pregnant women. The decision, led by pharmacist Frances Oldham Kelsey, was essential to prevent a greater tragedy in the US. Even so, as the drug was distributed for clinical trials in the country, dozens of children ended up being affected.

The problem caught the attention of the international community and led to stricter clinical trials and product safety monitoring. Laws for marketing drugs were created and new regulatory agencies popped up, like the European Medicines Agency (EMA) in 1995. In Brazil, the National Commission for Ethics in Clinical Research (CONEP) was created in 1996 and Anvisa in 1999.

“Regulatory harmonization has been established, which facilitates, for example, the approval of drugs from one country to another. Each country has its own regulatory agency, but there are international standards to be followed,” explains Paulo Lee Ho, Product Development and Innovation Manager at Butantan.

Clinical trials are now divided into phases: phase 1, which assesses safety in a small group of patients; phase 2, which analyzes safety and efficacy in a larger population; phase 3, which serves to confirm efficacy in a much larger number of participants; and phase 4, which occurs after the vaccine or treatment has been approved, to monitor long-term adverse events.

Keeping pace with scientific advances in Brazil and around the world, Butantan began investing in its own clinical trials in the 2000s, aiming to develop new products for Brazilian public health. The Special Laboratory for Clinical Trials and Pharmacovigilance was created. Initially, research was conducted by partner institutions. Gradually, the Institute expanded its infrastructure and, in 2011, officially created the Center for Clinical Trials and Pharmacovigilance, with a team dedicated to coordinating studies in humans.

Early 21st century: Butantan's first clinical trials
In the early 2000s, an initiative by the then director of the Butantan Institute, Isaias Raw, would give rise to the institution's first clinical study, which reached phase 2/3. The drug evaluated was pulmonary surfactant, a candidate for the treatment of Respiratory Distress Syndrome in newborns. The disease, which mainly affects premature babies, occurs when the lungs do not produce enough surfactant, a substance that coats the pulmonary alveoli and allows them to expand and contract properly for breathing.

"As there was no domestic production of surfactant, Professor Isaias made an agreement with a private company to isolate and study the surfactant in order to manufacture it in Brazil. Isaias was a visionary and saw Butantan as a place for developing new products," recalls Maria da Graça Salomão, Medical Writing Coordinator at Butantan, who is part of the Clinical Trials and Pharmacovigilance Center team.

To conduct the study, which took place between 2005 and 2007, Butantan established a partnership with 19 Neonatal Intensive Care Units throughout Brazil, as well as researchers with experience in clinical trials from institutions such as the Children's Institute of the Hospital das Clínicas of the University of São Paulo (USP) and the Albert Einstein Israeli Hospital.

Another study conducted at the time was phase 1 of the pentavalent rotavirus vaccine, between 2007 and 2008, which involved collaboration between NIAID-NIH in the United States, the Institute of Tropical Medicine, the USP School of Medicine, the Adolfo Lutz Institute, and the Santa Casa School of Medical Sciences. Rotavirus is one of the main causes of severe diarrhea in children under 5 years of age, and the vaccine available at that time protected against only one of the five then-known strains of the virus.

“There were several meetings with Anvisa, which was also still maturing in the area, and many collaborations with other institutes, which made the study a success,” comments Neuza Frazatti Gallina, Process Development Manager at the Butantan Viral Vaccine Pilot Laboratory.

The project was eventually interrupted due to the dengue epidemic in 2010, when the Institute had to take another path to address the more serious emergency that was approaching: the number of cases of the disease had tripled compared to the previous year. It is also worth noting that there was already a vaccine for rotavirus on the market, but none against dengue.

In partnership with the US National Institutes of Health (NIH), Butantan kicked off what would become one of the largest clinical trials ever conducted in Brazil: the clinical trial of its dengue vaccine candidate. Including more than 16,000 volunteers from across the country, the study is considered a turning point for Butantan, which would later provide support in the fight against the Covid-19 pandemic. The infrastructure created also made it possible to study a vaccine against another neglected disease, chikungunya, which was approved by Anvisa in April this year.

Butantan's Clinical Trials and Pharmacovigilance Center now has 81 professionals from different specialties, such as industry, epidemiology, clinical medicine, and research. The expansion allowed for the consolidation of the area, in accordance with international standards of good practice and quality rules for products under development.