Bladder cancer patients who run out of options often face a grim choice: life-altering surgery to remove the bladder, or living with a disease that might kill them if it spreads to the rest of the body. Now, a quirky little invention — a small pretzel-shaped device that sits inside the bladder — may be rewriting that script.
Researchers call it TAR-200, and it works by releasing the chemotherapy drug gemcitabine slowly over weeks. Instead of a quick splash of chemo that washes away in hours, TAR-200 lingers. It steadily releases medicine into the bladder lining for up to three weeks per cycle.
“The theory behind this study was that the longer the medicine sits inside the bladder, the more deeply it would penetrate the bladder and the more cancer it would destroy,” explained study leader Dr. Siamak Daneshmand of USC Norris Comprehensive Cancer Center. “And it appears that having the chemotherapy released slowly over weeks rather than in just a few hours is a much more effective approach.”
How TAR-200 Stacks Up Against Standard Care
Bladder cancer is tricky because most cases are “non-muscle-invasive,” meaning the tumors haven’t burrowed into the bladder wall. Standard treatment involves a live bacterium, Bacillus Calmette-Guérin (BCG), that rallies the immune system to attack the cancer. But in many patients, BCG eventually fails. At that point, the default option is radical cystectomy, a surgery to remove the bladder and nearby organs like the prostate and seminal vesicles in men, or the uterus and ovaries in women.
That’s a daunting prospect. Complication rates hover around 50 to 70 percent, with a 90-day mortality risk of about 5 percent, especially for older patients. Unsurprisingly, fewer than one in five eligible patients choose it.
This is where TAR-200 enters the story. The SunRISe-1 trial, run across 142 sites in 14 countries, tested the device in more than 200 patients whose cancers had returned after BCG.
The results stunned oncologists. In one key group — patients with carcinoma in situ, the most stubborn form of the disease — 82.4 percent saw their tumors vanish. Even better, many stayed cancer-free for more than two years.
By comparison, other recently approved drugs like pembrolizumab (Keytruda) or gene therapy treatments achieve complete response rates in the 40 to 60 percent range. “TAR-200 monotherapy demonstrated the highest single-agent CR rate reported to date in this setting,” the researchers noted.
What Patients Experienced
The treatment is relatively simple: doctors insert the device through a catheter in an office visit. Patients keep it inside for three weeks before replacement.
Side effects were generally mild — mostly urinary tract irritations like frequent urination, burning, or bladder pain. These typically faded in about three weeks. Only 3.5 percent of patients stopped therapy due to side effects.
In contrast, when TAR-200 was paired with an immune checkpoint drug called cetrelimab, effectiveness dropped and side effects spiked. That finding surprised some researchers, since combining chemo and immunotherapy often boosts outcomes in other cancers. Here, the pretzel worked best solo.
A Shift in Bladder Cancer Treatment?
The implications are huge. Bladder cancer ranks as the sixth most common cancer in the U.S., affecting around 80,000 people annually. About half of those with high-risk, non-muscle-invasive disease will relapse after standard care.
For decades, the field has been starved for innovation. A handful of new bladder-sparing drugs emerged in the past five years, but adoption has been slow due to side effects, cost, or limited durability.
That’s why experts are watching TAR-200 so closely. Not only did it shrink tumors, but it also kept patients out of the operating room. In the trial, more than three-quarters of patients were still cystectomy-free after two years.
Dr. Daneshmand summed up the mood among researchers: “We are at an exciting moment in history. Our mission is to deliver cancer-fighting medications into the bladder that will offer lasting remission from cancer, and it looks like we are well on our way toward that goal.”
For now, TAR-200 is under FDA priority review, which means regulators will decide faster than usual whether it can be approved for wider use. If cleared, it could become the first bladder implant of its kind — and potentially change how doctors treat one of the most stubborn cancers around. TAR-200 is manufactured by the health care corporation Johnson & Johnson.
The results appeared in the Journal of Clinical Oncology.
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