Scientists are edging closer to defeating a longtime enemy
of human health: hemophilia, the lack to make blood clots.
After trying for many years to develop a gene therapy to
treat this disease, researchers are beginning to succeed.
In recent
experiments, brief intravenous infusions of powerful new treatments have rid patients — for now, a minimum of — of a condition that has shadowed all of them
their lives.
There are setbacks — years of failed clinical trials and
dashed hopes. Just last week, a biotech company reported that gene therapy
mostly stopped working in two of 12 patients in one trial.
But the overall trajectory has been forward, and new
treatments are expected by many experts to be approved during a few years.
No one is saying yet that hemophilia is going to be cured.
Currently the gene therapy — which uses an epidemic to deliver a replacement
gene to cells — can only be used once. If it stops working, the patients lose
their advantages.
For now, “we are anticipating that this is often a
once-in-a-lifetime treatment,” said Dr. Steven Pipe, director of the hemophilia
and coagulation disorders program at the University of Michigan and a lead
investigator of a clinical test conducted by the biotech company BioMarin.
The successful treatments are so recent it's hard to
mention how long they're going to last.
except for the few patients who are
through the clinical trials successfully, life after treatment is so different
that it’s something of a shock.
There are 20,000 hemophilia patients within us who lack
one among two proteins needed for blood to clot.
It’s a genetic condition, and
therefore the gene for blood coagulation sits on the X chromosome. Virtually
all people with hemophilia are men.
Those most severely affected must inject themselves every
few days with the missing proteins, coagulation factor VIII, or Christmas factor.
The shots keep hemophiliacs alive, but levels of clotting proteins drop
between injections.
Even with regular injections, people with hemophilia risk
uncontrolled bleeding into a muscle or joint, or maybe the brain. they need to
be extremely careful.
Once bleeding begins, a joint may bulge because the joint
space fills with blood. When the bleeding stops, the joint could also be
damaged.
Even a routine flight is risky, said Mark Skinner, a
57-year-old attorney in Washington with hemophilia who may be a past president
of the planet Federation of Hemophilia.
“Carrying luggage around, you'll twist the incorrect way
and immediately trigger a bleed,” he said. “Or you'll get hit with a cart
taking place the aisle.”
People with hemophilia often are taught as children to
avoid most sports and to seek out professions that will not require much
physical activity. Many move to cities to realize easier access to treatment.
They may change jobs to urge insurance needed to hide
medical bills for hospitalizations and surgeries which will reach $1 million a
year, plus a mean of $250,000 to $300,000 a year for the clotting proteins.
(The shots alone can cost the maximum amount as $1 million per annum.)
Despite their vigilance, most with the severe disease
eventually develop permanent joint damage from bleeds, often resulting in
surgery for ankle fusion or hip or knee replacements at an early age. Most
accept chronic pain from past bleeds.
For older patients, there's a further complication. The
clotting proteins utilized in the 1980s were contaminated with H.I.V. and
hepatitis C. Nearly everyone with hemophilia got infected.
Now, though, researchers see the beginning of a replacement
era.
“It’s a very optimistic time,” said Dr. Lindsey A. George,
a hematologist at the Children’s Hospital of Philadelphia and a PI for Spark
Therapeutics, one among several companies developing gene therapies for
hemophilia.
Imperfect successes
The goal of gene therapy is to scale back or eliminate
patients’ need for injections with coagulation factor and to scale back the
amount of bleeds.
The gene to be inserted depends on whether the patient has
hemophilia A, caused by a mutation within the gene for antihemophilic factor,
or hemophilia B, caused by a mutation within the gene for coagulation factor
IX.
Although the symptoms are equivalent to both sorts of
the disease, hemophilia A is far and away from the foremost common.
A handful of biotech companies are now rushing to urge
their gene therapies to plug.
Spark, with gene therapy for hemophilia B, and
BioMarin, another biotech company, with an identical treatment for hemophilia A, are starting large, final-phase clinical trials.
(Pfizer is taking up the
event of the Spark drug.)
Results from the 2 companies’ preliminary trials weren't
perfect.
Patients in Biomarin’s hemophilia A trial got, on the
average, normal or above normal levels of an antihemophilic factor in their
blood, but within the second year, those levels dropped to a median of 46
percent. It’s not clear why.
Patients in Spark’s hemophilia B trial only reached on the
average 35 percent of normal blood levels of the Christmas factor.
But those
levels have remained steady for the 2 years they need following.
The good news is that those levels are sufficient for blood
to clot because normal levels are quite people's need.
After dreaming of a cure
for many years, some treated patients try to regulate to newfound freedom.
John Brissette, 39, a person interface designer in Hanover,
Mass. said hemophilia A always dominated his life.
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