From a pig kidney transplant to restoring genetic deafness, 2024 was a year full of medical breakthroughs.
The breakthroughs include the discovery of a cause of an autoimmune disease, the development of a "game-changing" drug and potential hope for those experiencing end-stage organ failure.
Here are five of the biggest highlights in medical achievements this year:
MORE: FDA approves gene therapies for sickle cell disease, a 'functional cure' for manyChildren with hereditary deafness regained their hearing thanks to a type of gene therapy, according to the results of a clinical trial published in the medical journal The Lancet in January.
Investigators from Mass Eye and Ear, a specialty hospital in Boston, examined six children who had a form of genetic deafness called DFNB9, which is caused by a gene mutation that interferes with the transmission of sound signals from the ear to the brain.
Gene therapy involved the use of an inactive virus carrying a functioning version of the gene, which was introduced into the inner ears of the six children.
After 26 weeks, five of the six children recovered their hearing and could even conduct "normal conversation."
"Children with this genetic hearing loss…the only treatment option for them until now is [a] cochlear implant," Dr. Zheng-Yi Chen, an associate scientist in the Eaton-Peabody Laboratories at Mass Eye and Ear and study co-investigator, told ABC News. "And of course, [a] cochlear implant can help them tremendously, but it's with its own limitations."
"But with this gene therapy, the children regain hearing, and they were able to speak. So, in a way, the life is totally transformed," he continued. "This study really opened up the whole field that, in the future, we'll be able to develop a treatment for other [types] of genetic hearing loss, for which there is no treatment at all at the moment."
Surgeons at Massachusetts General Hospital (MGH) conducted the world's first genetically-edited pig kidney transplant into a living human in March 2024.
During a four-hour procedure, a surgical team connected the pig kidney's blood vessels and ureter - the duct that carries urine from the kidney to the bladder - with those of 62-year-old Richard Slayman, a man living with end-stage kidney disease.
"For patients with kidney failure, we know that transplantation is the best treatment option, but unfortunately, we face an immense organ shortage," Dr. Leonardo Riella, medical director of kidney transplantation at MGH, told ABC News. "So, we have over 100,000 patients waiting for a kidney transplant in the U.S., and more than 17 patients die every day on the waiting list."
"So, the idea here is, how can we overcome this organ shortage barrier? And having kidneys from another species that could be delivered in a timely manner for these patients once they develop kidney failure could be game-changing for the entire field," he added.
Slayman passed away in May of this year, but there is no evidence it was the result of the transplant, according to MGH.
Riella said over the course of Slayman's care, much was learned about how to best deliver care when using animal organs for transplants in the hopes of making the treatment more widely available to patients waiting for a new organ.
A team at Brigham & Women's Hospital and Northwestern Medicine said they have discovered a cause of the autoimmune disease lupus and a possible way to reverse it.
Lupus sees the body's immune system mistakenly attack its own healthy cells and tissues, which can cause inflammation and damage in organs or systems, according to the Centers for Disease Control and Prevention.
MORE: Woman speaks out after receiving gene-edited pig kidney transplantIn a study, published in the journal Nature in July, researchers compared blood samples from 19 lupus patients to 19 patients without the condition and found imbalances in the types of T-cells lupus patients produce.
T-cells are a certain type of white blood cell that plays a crucial role in the body's immune response to the disease.
"We've identified a fundamental imbalance in the immune responses that patients with lupus make, and we've defined specific mediators that can correct this imbalance to dampen the pathologic autoimmune response," co-corresponding author Dr. Deepak Rao, a rheumatologist at Brigham and Women's Hospital and co-director of its Center for Cellular Profiling, said in a press release at the time.
In September, the FDA approved the first new class of drug to treat people with schizophrenia in more than 30 years.
The pill, called Cobenfy - manufactured by Bristol Myers Squibb - combines two drugs, xanomeline and trospium chloride, and is taken twice a day.
Clinical trials showed the combination helped manage schizophrenia symptoms such as hallucinations, delusions and disorganized thinking.
Dr. René Kahn, chair of psychiatry at the Icahn School of Medicine at Mount Sinai, said it took many years to develop the first medications for schizophrenia, which are effective in preventing psychosis and work by blocking dopamine receptors.
"Blocking the dopamine receptor directly or indirectly is very unpleasant. Sometimes for patients, they can have unpleasant side effects. It can decrease their energy, it can make them feel depressed, and it can give them Parkinsonian side effects," Kahn told ABC News.
He described Cobenfy as "game-changing in the sense that this is the first drug that doesn't directly - with the emphasis on directly - influence the dopamine system and certainly doesn't block dopamine receptors. So that's very important, because it may show that we don't have to directly block or affect the dopamine system but can do that through a different mechanism."
Kahn said the next step will be monitoring the drug as it is prescribed to thousands of schizophrenia patients to ensure it works and that side effects are minimal.
The FDA authorized the first over-the-counter combination COVID-19 and flu test outside of emergency use in October.
The Healgen Rapid Check COVID-19/Flu A&B Antigen Test can be purchased at a pharmacy or other stores without a prescription.
While there are other over-the-counter combination tests currently available, this is the first to be marketed to consumers using the traditional approval pathway outside of a public health emergency, according to the FDA.