ISIS Press Release 07/04/06
London Drug Trial Catastrophe – Collapse of Science and Ethics
An unconventional member of a new class of drugs, all known to have caused
serious side effects including deaths, has been approved for clinical trial
based solely on unpublished animal tests. Dr.
Mae-Wan Ho and Prof. Joe Cummins
A fully referenced version
of this article is posted on ISIS members’ website. Details here
Drug trial that went horribly wrong
On 13 March
2006, six healthy young volunteers took part in a clinical trial and became
violently ill minutes after having been injected with a drug developed to
fight autoimmune disease and leukaemia [1-5]. One of the two additional volunteers
injected with a placebo who showed no ill effects recalled to newspaper reporters
[2]: “The men went down like dominoes. They began tearing their shirts off
complaining of fever, then some screamed that their heads were going to explode.
After that they started fainting, vomiting and writhing around in their beds.”
One man became especially
bloated, “like the Elephant Man”. All six suffered multiple organ failure,
and were admitted to intensive care. The Medicines and Healthcare products
Regulatory Agency (MHRA), which gave approval for the trial, immediately withdrew
authorisation; and an international warning went out to prevent the drug being
tested abroad.
Two weeks later,
two men remain in hospital; one still in intensive care and conscious, the
other said to be making good progress [6]. The case is under investigation
by the MHRA. But serious questions should also be asked concerning the MHRA’s
approval for the trial in the first place.
A new kind of drug previously untested on humans
The drug tested,
TGN1412, was developed by the company TeGenero based in Würzburg, Germany, and manufactured by Boehringer Ingelheim. But another company, Parexel International Corporation based
in Lowell, Massachusetts, USA, was commissioned to carry out the clinical
trial. The six young men were paid a small fee to participate
in the experiment [1-5], according
to one of them, £2 330 (US$4 070).
While Paraxel said
it followed the rules for drug research, a former executive of the company,
who asked to remain anonymous, expressed surprise that the drug was tested
on so many persons at once. “It is common sense not to dose six individuals
with the drug at once where there is no prior human experience,” he said [2].
TeGenero describes
TGN1412 on its website as [7] “an immunomodulatory humanized agonistic anti-CD28 monoclonal
antibody that is being developed for the treatment of immunological diseases
with a high unmet medical need, such as multiple sclerosis, rheumatoid arthritis
and certain cancers”. A monoclonal antibody (MAB) is an immunoglobulin
protein made by the descendants of a single antibody-producing cell.
In a statement updated
24 March 2006 [8], the company disclosed that TGN1412 binds
to the cell marker CD28 present on the cell surface of T lymphocytes, causing
more T cells to be created. It claimed that the safety of TGN1412 was extensively
tested on “rabbits and monkeys”, that “there were no drug related deaths despite
administering doses up to five hundred times the dose to be used in the phase
1 clinical trial”. Nevertheless, in pre-clinical tests, 2 monkeys experienced
a transient increase in the size of lymph nodes, but TeGenero considers that
not a drug related side effect.
Family members of
the human volunteers were told that a dog died in testing, TeGenero denied
that TGN1412 was tested on dogs, but stated that academic research which led
to the initial development of TGN1412 did include testing on mice and rats.
TeGenero had applied
to conduct the same test and gained approval both in the UK and in Germany,
though the test in Germany had not yet started and has been abandoned.
It said that the
drug was given to volunteers “within a period of 2 hours”, as “approved by
the MHRA and the local ethics committee”. TGN1412 was the company’s “most
advanced product candidate and the first to reach human testing.”
What went wrong?
No one knows what caused
the shocking reactions in the volunteers. An error in drug dosing or manufacture
was suspected [9]. Simon Gregor, spokesperson for UK’s MHRA, said managers
at Northwick Park Hospital where the trial took place were so surprised that
they called in the police to check for evidence of a crime. But MHRA and other
investigations found no evidence of crime or technical error.
Was a contaminant
in the MAB drug responsible? MAB drugs typically begins with extensive genetic
engineering to produce the appropriate protein antigen, which is injected
repeatedly into mice together with transgenic cells producing the protein,
in order to challenge the mice to produce antibodies to the protein. The mice
are then killed and the spleen cells isolated and fused with cancer (lymphoma)
cells to create ‘hybridoma’ cells. Clones of single hybridoma cells are then
obtained to give permanent cell lines, each of which grows and secretes a
single antibody protein (monoclonal antibody) continuously. ‘Humanized’ monoclonal
antibodies would have involved additional genetic engineering to alter the
monoclonal antibody protein molecule so that it would not be rejected when
given to human subjects. Each step in this complicated process could have
introduced dangerous contaminants.
An interim report
from MHRA said that the drug did not appear to have been contaminated, “or
to have contained anything other than the correct ingredients”, said Professor
Kent Woods, the chief executive of the MHRA, which regulated 350 Phase 1 clinical
trials (first testing on humans) in the UK every year. The report also cleared
Paraxel, which appeared to have run the trial according to the agreed protocol,
with the correct dose given to the patients [10].
More and more, the suspicion has turned onto TGN1412 itself, which may have
triggered the T cells to release a toxic flood of cytokines (cell signalling
molecules), or the T cells may have attacked the body’s own tissues, leading
to multiple organ failure [9, 11]. But MHRA, TeGenero and Paraxel all maintained
that the volunteers’ reactions were “unforeseeable”. TeGenero’s chief scientific
officer Thomas Hanke issued a statement on 17 March: “Extensive preclinical
tests showed no sign of any risk.”
Henke told Science magazine that a rodent version of
TGN1412 was tested extensively at high doses in rats and mice, with no ill
effects; and TGN1412 itself was given to 20 cynomolgus monkeys in an unpublished
study, after it was shown that their T cells were activated in the same way
as human cells, with no significant adverse effects other than a brief increase
in lymph node size. Simon Gregor of MHRA said that they have gone back to
the files and there was nothing in the documentation that would cause them
to think there was a concern.
We do not know what
the documentation contained, but disagree that the problems were “unforeseeable”.
The problems should have been anticipated
At least one drug, CTLA4
monoclonal antibody, which binds to a different cell marker, have caused side
effects in human trials, including skin rashes and gut reactions, which were
controlled with steroids.
In fact, there are
over 355 MAB drugs in clinical development, and the US Food and Drug Administration (FDA) has granted approval
to18 so far, mainly for cancer
treatment and control of immune system disorders. There is warning posted on every one of the approved drugs,
as one of us has readily discovered and compiled the list (“Warning on FDA
approved monoclonal antibodies”, this series). So it is difficult to believe
that the problems were unanticipated as claimed.
On the contrary, the problems associated with MAB drugs are widely
recognized. One drug approved for treating multiple sclerosis (MS) was associated
with several deaths from brain infections, probably because it blocked immune
cells migrating to the brain to fight infections. That drug was voluntarily
suspended pending further studies. The other MAB drugs approved are almost
without exception associated with severe side effects, in many cases including
death. These drugs provide, in
most instances, treatment of last resort for terminal or highly
debilitating disorders. For that reason, the risk of administering the treatment
has been deemed acceptable provided that consent for treatment is truly informed. I
The problems associated with up-regulating the immune system are
also well known, and include inflammation of the eye, skin, gut, pituitary
gland along with cases of hepatitis and loss of skin pigmentation [12]. A humanized MAB used to
treat colon cancer caused 17 percent of the cancer patients to experience
adverse immune events [13]. Initiation of such adverse events in susceptible
patients could be detected by first administering a low dose of the drug,
so those patients could be removed from further treatment with high doses
[12]. In the London drug trial, the dose administered to all six volunteers
must have been sufficiently high to cause all of them to become critically
ill.
Another
factor that should have made those involved in the London trials much more
cautious is that the drug tested was unusual even among monoclonal antibody
drugs.
Superagonist monoclonal antibodies are unconventional
Soon after the first monoclonal antibodies were raised
against the cell surface molecules of white blood cells in the later 1970s,
researchers have realised that they could be used to change immune responses,
potentially for therapeutic purposes. The majority of the antibodies block
immune functions or augment them when used in conjunction with other reagents.
A much smaller subset of antibodies activate white blood cells autonomously,
and are defined as superagonists [14, 15].
Natural activation
of T cells requires both the T cell antigen receptor (TCR) and T cell marker
CD28 to be stimulated by specific ligands (diffusible signal molecules), causing
the TCR and CD28 respectively to become cross-linked and clump together on
the cell membrane. What happens downstream is not well understood, but is
thought to involve cross talk between the clumped TCR and CD28 patches at
the cell membrane.
In experimental systems,
the natural ligands of TCR and CD28 can be replaced by specific MABs.
There are two types
of MABs that bind to CD28 to stimulate T cells, conventional MABs that depend
on simultaneous stimulation of TCR, and superagonist MABs that can give full
activation of T cells without TCR stimulation. Researchers from TeGenero working
with other laboratories showed that superagonist and conventional rat and
human CD28-specific MABs bind at different sites, and that the superagonist
binding site is conserved across the evolutionary divide separating rodents
and humans [14]. They also claimed previous research in the rat model showed
that superagonist CD28 MABs were highly potent stimulators of T cell proliferation
in vivo without apparent toxicity, and were
ready to exploit the MABs for therapeutic purposes.
Animal tests consist of “unpublished data”
Although TeGenero claimed
to have carried out extensive animal testing of TGN1412, it provided no scientific
papers on the tests. A review published by TeGenero in 2005 [15] referred
solely to “unpublished data” as far as animal testing was concerned.
The review referred
to studies in rats and mice given superagonist anti-CD28 MABs, in which a
transient but significant increase in overall T cell numbers was found, without
unleashing a toxic “cytokine storm”; and the researchers concluded that, “the
lymphocytosis induced by CD28 superagonists appears to be benign and well
tolerated.” A dose range 0.5mg/kg to 5mg/kg body weight led to a transient
increase in the proportion of T regulatory cells from 5 to 20 percent, while
absolute cell numbers increased up to 20 fold. Low doses of anti-CD28 MABs
(0.5m/kg body weight per rat) appeared to expand T regulatory cells without
inducing overall T cell increase; hence it was concluded that CD28 superagonist
stimulation in vivo leads to
the preferential expansion and strong activation of naturally occurring T
regulatory cells over other T cells.
The review claimed
that: “Efficacy of CD28 superagonist therapy has so far been evaluated in
animal models of both peripheral and central nervous system inflammation as
well as in a model of human rheumatoid arthritis.” These animal models showed
that CD28 superangonist “prevented or at least greatly mitigated clinical
symptoms when given prohylactically – that is, before the animals showed signs
of clinical disease (unpublished data).” And, “even after the onset of clinical
symptoms therapeutic CD28 superagonist administration rapidly stopped disease
progression and induced remission.” Consequently, for “successful therapy,
as for Treg cell expansion, low doses of CD28 superagonist (0.5mg/kg body
weight) were sufficient (unpublished data).”
The fallout
The dust from the catastrophe
has far from settled. It has left the scientific and medical community stunned,
and serious soul searching began almost immediately in the aftershock.
UK’s top science journal Nature reported the trial under the headlines,
“London’s disastrous drug trial has serious side effects for research”, predicting
tighter restrictions on clinical research and closer scrutiny of the private
companies that carry out the majority of clinical trials [16].
The report raised a number of key questions: Was informed consent adequate?
Were the right subjects recruited for the trial? Were the right doses given?
Did the company carrying out the trial behave responsibly? Some observers say
that the company TeGenero should have been more cautious about the drug as it
bypasses the immune system’s natural control mechanism; as immunologist Angus
Dalgleish of St. George’s Medical School in London said, “all hell can break
loose”.
Parexel International, the company contracted to do the clinical trial, operates
in 39 countries. Ethicists in the United States have called for the careful
scrutiny of a newly loosened set of rules for making and testing drugs in human
trials, as well as the lucrative business of contract research organizations
(CROs) such as Paraxel. Bioethicist Art Caplan is concerned that CROs are tacitly
encouraged not to focus on protecting human subjects. He said CROs are often
told by pharmaceutical companies to “just get us the data on the deadline”,
and “don’t get asked questions on how that’s being done.” The Association of
CROs boasts that CROs conduct clinical trials 30 percent more quickly than the
pharmaceutical companies that hire them.
The London drug trial episode came in the wake of 11
otherwise healthy people who tested positive for tuberculosis in Montreal,
Canada, after they were paid to volunteer for research conducted by a private
company. The volunteers apparently caught TB from an infected subject they’d
been housed with as part of the study paid for by a Canadian company, but
conducted by the CRO SFBC International.
Writing in the Philadelphia Daily News, Caplan expressed
doubt that informed consent and safety were given the priority required to
protect the human volunteers taking part in such studies [17].
“The recruitment
of the participants into the British trial certainly left much to be desired
ethically.” Caplan wrote. The website recruiting volunteers said almost nothing
about risks, but went on and on about good pay, free medical care, free food
and “plenty of time to read or study or just relax, with digital TV, pool
table, video games, DVD player and free internet access.”
The other CRO, SFBC
International, has problems beyond Montreal. The company’s major facility
for housing subjects in long-term studies in Miami had received numerous safety
and fire-code violations. When subjects went public with complaints, at least
three of them said they SFBC officials bullied them and threatened them with
deportation.
Twenty years ago,
Caplan said, most clinical research was conducted in academic medical centres,
and most research was paid for with government money. Now, private CROs running
studies for pharmaceutical and device companies are a $14 billion industry
in the United States alone. A lot of this research is done using poor people
or students, sometimes in the United States, but often in Europe, India and
Southeast Asia.
The role of the regulatory agency should also come under careful scrutiny.
Why did the MHRA allow the tests to be carried out simultaneously on all six
volunteers? Did it have all the information available when it approved the trial?
Did it make sure that informed consent was adequate?
In Germany, the local public prosecutor in Würzburg is investigating whether
any criminal wrongdoing was involved [16]. The Paul Ehrlich Institute, which
authorises human trials of biological drugs, announced it will tighten regulation
of the first tests of such drugs in people. Johannes Löwer, president of the
Institute based in Langen, asked why six people were treated at the same time,
instead of starting with one. He said his Institute will start requiring sequential
rather than simultaneous administration of ‘high risk’ monoclonal antibodies
such as TGN1412, which activates the immune system.
Have the standards
of science and ethics both collapsed in the new ethos of the “knowledge economy”
that promotes wealth creation above all else?
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