This month saw one of the worst drug trial debacles in memory, when a healthy volunteer participating in a Phase 1 study in France died within days of receiving an experimental drug for anxiety and chronic pain. Four other volunteers who took the same dose were hospitalized with hemorrhagic lesions in the brain, although all now seem to be recovering. In the wake of this tragedy, independent chemists and groups such as the London-based Royal Statistical Society are renewing calls for more transparency in clinical trials and earlier public identification of experimental compounds. Meanwhile, the company, Bial Pharmaceuticals of São Mamede do Coronado, Portugal, has refused to turn over its preclinical data to French authorities, citing trade secrecy.
Whether the incident will lead to changes in how trials are regulated is still unknown. A previous trial disaster in London in 2006 spurred several groups to recommend new safety guidelines for Phase 1 studies, some of which appear to have been violated in the Bial trial. The French National Agency for Medicines and Health Products Safety (ANSM) has launched an investigation into the incident, and other agencies are considering a response. The story has received extensive media coverage (see Nature, Forbes, and Science stories).
Bial Pharmaceuticals declined to comment for this article, but in a January 19 press release the company said it was “deeply shaken” by the tragedy and declared, “It is Bial’s absolute priority to find the causes of this serious incident.” As of January 29, the company had not issued further information on its website. Other researchers worry that the fiasco may shake public confidence in trials and make recruitment more difficult. “We need to better understand how this happened, and how we can avoid it in the future,” Bruno Vellas at the University of Toulouse, France, wrote to Alzforum.
Promising target, unexpected disaster
So far, no one knows what went wrong. The experimental compound was designed to inhibit fatty acid amide hydrolase (FAAH), an enzyme that breaks down endogenous cannabinoids such as anandamide in the brain. FAAH inhibition allows these cannabinoids to accumulate. Because cannabinoids dull pain and relax people, several companies are developing FAAH inhibitors to treat pain, anxiety, Tourette’s syndrome, and cannabis withdrawal. For example, Merck’s MK-4409, Pfizer’s PF-04457845, and Vernalis’ V158866 are being tested in clinical trials. To date, these compounds have been safe in humans, raising the possibility that the Bial drug may have hit the wrong target. On January 17, Janssen Research and Development announced that it was voluntarily suspending dosing in two Phase 2 trials of its FAAH inhibitor JNJ-42165279 in people with social anxiety and depression, respectively. The company said no participants had developed adverse reactions and this was merely a precaution. No FAAH inhibitors have yet reached the market.
FAAH inhibitors have also been proposed as potential therapeutics for a range of neurodegenerative conditions, including Alzheimer’s, Parkinson’s, Huntington’s disease, and traumatic brain injury (for review, see Micale et al., 2007; Hwang et al., 2010). In animal studies, endocannabinoids rise after neuronal injury and appear to promote cell survival and lower inflammation. Some studies suggest that endocannabinoids could ameliorate Aβ toxicity and neuronal loss (see Ramírez et al., 2005; Milton, 2002), while another reported high levels of FAAH around plaques in AD brains (see Benito et al., 2003).
Bial began preclinical studies with the compound in question, BIA 10-2474, in 2009, according to a company press release. The Phase 1 trial began in June 2015 and was run by the contract research organization Biotrial, headquartered in the western French city of Rennes. Biotrial recruited 116 healthy volunteers between the ages of 18 and 55 to test the safety of both single and multiple ascending doses at the University Hospital of Rennes, with about a quarter of the cohort receiving placebo. The first 84 participants who took the active compound reported no problems. On January 7, six volunteers began taking the highest tested dose once daily for a planned 10 days. Bial has not disclosed the dosage used.
Three days later, one of the volunteers developed severe neurological symptoms similar to a stroke, according to Gilles Edan, a neurologist at Rennes Hospital. Biotrial halted the trial the next day. The patient deteriorated quickly and died within days, while four of the other participants in that treatment group developed similar symptoms and were hospitalized at Rennes. Edan said in a press conference January 15 that the patients had hemorrhagic and necrotic lesions deep in their brains on MRI scans, and added that doctors were trying to control the inflammation with corticosteroids. Since that time, all four patients have improved, with two discharged to their homes and two still in care facilities near their residences. It is unclear if they will suffer lasting neurological damage. A Bial press release from January 19 announced, “[We] expect a full recovery.” The sixth member of the cohort did not develop symptoms. Rennes hospital is in the process of calling back participants who took lower doses. So far it has found no MRI abnormalities in the first 44 people scanned, according to a January 26 update from the hospital.
History repeats itself
Such severe adverse events are very rare in clinical trials, according to the European Medicines Agency (EMA). Since 2005, about 14,700 Phase 1 trials have taken place in the EU, including 3,100 first-in-human studies. A major adverse incident occurred only once, Rebecca Harding at EMA, London, wrote to Alzforum. That was in 2006, in a Phase 1 trial of the TGN1412 monoclonal antibody by the now-bankrupt German company TeGenero. The antibody targeted a T cell receptor and was intended to treat autoimmune diseases and lymphoma. Volunteers were given a dose 500 times smaller than had been found safe in animals; however, within minutes they developed fever and pain. Within eight hours their organs began to fail, and all six had to be admitted to intensive care. Researchers later determined that the antibody had triggered a massive release of cytokines, known as a “cytokine storm.” All six participants survived, although some sustained lasting damage such as loss of fingers and toes, and perhaps chronically compromised immune systems (for review, see Attarwala, 2010).
The TeGenero debacle prompted several investigations that resulted in revised safety recommendations. An Expert Scientific Group appointed by the U.K. Secretary of State issued a report that concluded TeGenero’s preclinical studies “did not predict a safe dose for use in humans.” Part of the problem was imperfect homology between the T cell receptor in cynomolgus monkeys and that in humans, which led to an unexpected reaction in patients, researchers said. Based on recommendations in this report, in 2007 the EMA released new guidelines for lowering risk in first-in-human studies. Clinical trial sponsors are expected to comply with these guidelines, and justify any deviation from them in the trial application, Harding wrote. Also in 2007, the Royal Statistical Society put forth its own set of independent but similar recommendations. One factor all the agencies stressed was the importance of dosing patients sequentially, rather than all at the same time as TeGenero did, when investigating drugs that have not been tried in humans before.
Initial efforts to find out if similar factors played a role in the Bial trial were hampered by secrecy. For the first week, no information was available on the chemical structure of BIA 10-2474 or the trial details, until French newspaper Le Figaro leaked the trial protocol on January 21. A day later, ANSM released the protocol, which it said Bial had turned over to it. At the same time, the agency complained that Bial had refused its request to disclose the product dossier for the compound, as well as the investigator’s brochure, which describes preclinical studies. The Royal Statistical Society called for the release of these documents, along with disclosing the actual doses given to volunteers and the regimen used for multiple dosing, in a January 22 statement. The society also urged the French investigation to include independent statisticians.
To some observers, details in the Bial protocol echoed the TeGenero trial. As in that trial, the BIA 10-2474 investigators appear to have administered doses to all members of each trial group at the same time, allowing any adverse reaction to affect the whole group. Andrew Grieve, a trial design expert at the clinical research organization ICON, Cologne, Germany, and a member of the Royal Statistical Society, noted that the protocol appeared to diverge from previous safety recommendations suggested by both the society and the EMA. However, he added, “It would be wrong of us to suggest that the protocol for this particular study was any worse than many that have been run previously.” To figure out what went wrong, analysts will need to know what pharmacokinetic data were available to support the dose-escalation decisions made in the Bial trial, Grieve wrote to Alzforum.
Compound structure raises red flag
The protocol also gave chemists their first look at the structure of BIA 10-2474. Companies commonly hide the identities of investigational drugs under code names, and bury the drug structures in patents among hundreds of variations on the same compound. Scientists have previously complained about the difficulties this practice causes for curation, drug repurposing, and analysis of potential drug interactions (see Southan et al., 2013). The Bial trial disaster kicked off days of online speculation on chemistry blogs, as researchers dug through Bial patents in search of likely candidates. The protocol, however, provided the chemical name BIA 10-2474, allowing chemists to tentatively identify it as a compound with the PubChem ID CID 46831476, disclosed in a 2009 Bial patent.
To glean clues as to how the compound may have wreaked damage, pharmacologist Sean Ekins at the consulting group Collaborations in Chemistry, Fuquay Varina, North Carolina, ran the structure through various online software packages. Using the Swiss Target Prediction program, he found that although FAAH popped up as the primary target, a number of other proteins rated highly as well. These included histone deacetylases, which regulate gene transcription, and macrophage-stimulating protein receptor, which could kick off an immune reaction (see blog). The results hint at potential off-target effects. “The compound looks pretty dirty,” Ekins told Alzforum. By contrast, the suspended Janssen inhibitor tested out as much more specific for FAAH in the same software programs, he added.
Alternatively, Ekins wondered if BIA 10-2474 might covalently bind another molecule, forming an adduct. He noted that the predicted structure for BIA 10-2474 contains a pyridine oxide, a reactive group found in very few drugs. Adducts are often recognized as foreign substances by the immune system and can provoke massive inflammation, in line with the symptoms described by Rennes Hospital.
However, at the moment this is all speculation. These theories need experimental verification, and for chemists working on this problem, the challenge will be to obtain the molecule, Ekins noted. Christopher Southan, who curates the Guide to Pharmacology database at the University of Edinburgh, U.K., wrote on his blog that industrial chemists have told him this structure looks difficult to synthesize. Many hope for greater cooperation from Bial. On January 29, Ekins noted the company has not yet responded to his request to obtain the compound for testing. “We’re trying to figure this out blind,” Ekins said.
It is too early to know what the long-term consequences of this incident will be. In addition to the ANSM’s investigation, the agency announced on January 21 that it would create a temporary Specialized Scientific Committee (CSST) to look into what went wrong. Other regulatory bodies are keeping an eye on developments. Harding at the EMA wrote to Alzforum, “EU authorities will look carefully at the findings to determine if further measures are needed to protect the health of clinical trial participants.”
Likewise, the U.S. Food and Drug Administration noted in a January 22 statement that it is “conferring with European regulators” and “is in the process of collecting and reviewing safety information pertinent to FAAH inhibitors under investigation in the U.S.” Tara Goodin at the FDA wrote in an email to Alzforum, “Given the recency of the tragic events in France and because we do not have all of the facts related to the conduct of the trial, the agency has not had the opportunity to consider the implications, if any, under FDA’s statutory and regulatory provisions.” She added that the U.S. Congress does not require Phase 1 trials to register on clinicaltrials.gov or submit results, although the NIH has requested this. Some companies voluntarily register Phase 1 trials.
“The main thing I can see that might come out of this is further clinical guidelines on targets whose human homologs are not well modeled by animal species, which seems to have been the case here, and with TeGenero as well,” Derek Lowe, a chemist who writes the “In the Pipeline” blog at Science Translational Medicine, in an email to Alzforum.
In the long run, will this incident weaken the public’s faith in drug trials? At the moment, no one can say, although some expect it will. “Such incidents are likely to have an adverse impact on recruitment, but we have not had any calls about this event here,” Jeff Cummings at the Cleveland Clinic Lou Ruvo Center for Brain Health in Las Vegas wrote to Alzforum. “This [event] is a tragedy for the individuals and their families. It reminds us that participants in trials are heroic and we need to honor them.”