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FDA grants approval for sickle cell drug


Casgevy is promising but cost prohibitive

The Food and Drug Administration, following a series of trial treatments, has approved a powerful treatment for sickle cell disease, a devastating illness that affects more than 100,000 Americans, the majority of whom are Black. 

The therapy, called Casgevy, from Vertex Pharmaceuticals and CRISPR Therapeutics, is the first medicine to be approved in the United States that uses the gene-editing tool CRISPR, which won its inventors the Nobel Prize in chemistry in 2020. 

“This is a pivotal moment in the field,” said Dr. Alexis Thompson, chief of the division of hematology at Children’s Hospital of Philadelphia, who has previously consulted for Vertex. “It’s been really remarkable how quickly we went from the actual discovery of CRISPR, the awarding of a Nobel Prize, and now actually seeing it being an approved product.”

The approval marks the first of two potential breakthroughs for the inherited blood disorder. The FDA has also approved a second treatment for sickle cell disease, called Lyfgenia, a gene therapy from drugmaker Bluebird Bio. Both treatments work by genetically modifying a patient’s own stem cells.

Until now, the only known cure for sickle cell disease was a bone marrow transplant from a donor, which carries the risk of rejection by the immune system, in addition to the difficult process of finding a matching donor.

Casgevy, which was approved for people ages 12 and up, removes the need for a donor. Using CRISPR, it edits the DNA found in a patient’s stem cells to remove the gene that causes the disease. 

“The patient is their own donor,” Thompson said.

“It’s a game-changer,” said Dr. Asmaa Ferdjallah, a pediatric hematologist and bone marrow transplant physician at the Mayo Clinic in Rochester, Minnesota. “To really reimagine and rediscuss sickle cell disease as a curable disease and not as this painful and debilitating chronic disease is hope enough with this news.”

Still, the new therapy is expected to be extremely expensive — potentially around $2 million per patient, according to a report from the Institute for Clinical and Economic Review, a nonprofit group that helps determine fair prices for drugs. The pricing strategy, experts argue, may place it out of reach for many families. What’s more, that price doesn’t include the cost of care associated with the treatment, like a stay in the hospital or chemotherapy.

“We really have to make sure that it is accessible,” said Dr. Rabi Hanna, a pediatric hematologist-oncologist at the Cleveland Clinic who has previously served on the advisory board for Vertex. “This could be an equalizer for people with sickle cell because many patients cannot pursue career options” because of the illness.

“It’s something families have been aware of in the early research stage and they’ve been very patiently waiting for years,” Ferdjallah said. “It’s been eagerly awaited by patients and families, but also by providers and physicians.”

In patients with sickle cell disease, red blood cells, which are usually disk-shaped, take on a crescent or sickle shape. This change can cause cells to clump together, leading to clots and blockages in the blood vessels, starving tissues of oxygen. Patients can experience excruciating pain, breathing problems and stroke.

Casgevy works by editing the DNA in a patient’s stem cells — which are responsible for making the body’s blood cells — so that they no longer produce sickle-shaped cells. 

LaRae Morning, 29, of Phoenix, was among the trial patients whose treatment was successful. 

Her doctors did not expect her to live past the age of 11. Her mother lost several jobs when Morning was a child and a teenager because of her frequent hospital visits.

In April 2021, Morning joined the clinical trial at Sarah Cannon Research Institute and HCA Healthcare’s The Children’s Hospital at TriStar Centennial in Nashville, Tenn., a decision she initially regretted. Living in Phoenix, she had to fly to Nashville once a month for treatment. It included several blood transfusions, which lasted eight hours each, and taking a medication, called plerixafor, which she recalled causing her intense stomach aches. When she started chemotherapy, her hair began to fall out and her skin changed color, resembling the appearance of a chemical burn. She also experienced nausea.

It took about six to seven months for her to feel back to normal following the CRISPR treatment. Now, she said, she’s feeling the benefits, going out to coffee shops, spending time with her friends and finishing her first semester of law school in Washington, D.C.

“Now that I’m here, I’m so happy that I did it,” she said of the trial. “I’m just like a regular person. I wake up and do a 5K. I lift weights. If I wanted to swim, I can swim. I’m still trying to know how far I can stretch it, like what are all the things I can do.”

That’s been the experience for several other patients in the trial as well, according to Dr. Monica Bhatia, chief of pediatric stem cell transplantation at NewYork-Presbyterian/Columbia University Irving Medical Center. Bhatia is a principal investigator at one of the clinical trial sites in New York City.

Following the treatment, most patients were going back to school, going to the gym or resuming other activities — “things that a lot of people take for granted,” she said — after about three to four months.        

“They’re really able to live life without restrictions,” Bhatia said.            

Dr. Haydar Frangoul, medical director of pediatric hematology-oncology for Sarah Cannon Research Institute, said he is hopeful the therapy will provide relief to more patients.

“I think this is a huge moment for patients with sickle cell disease,” said Frangoul, who was the lead investigator on the clinical trial and treated Morning.                                                                     

Although the treatment has been shown to be effective, since the trial is only set to run for two years, experts still don’t know about potential long-term effects.