Long-term outcomes of fixed-duration venetoclax–rituximab in relapsed/refractory chronic lymphocytic leukemia: impact of prior BTK inhibitor exposure and measurable residual disease in a multicenter real-world study

Chronic lymphocytic leukemia is a type of blood cancer that grows slowly but stubbornly, filling the body with too many white blood cells that do not work correctly. For decades, doctors treated this disease with chemotherapy, using powerful drugs to kill rapidly dividing cells. However, a new generation of treatments has arrived that works differently. Instead of attacking all fast-growing cells, these modern medicines target specific weaknesses inside the cancer cells themselves. One such weakness is a protein called BCL-2, which acts like a shield, preventing the cancer cell from dying naturally. Another weakness involves a different protein called Bruton tyrosine kinase, which helps the cancer cell survive and multiply. Doctors now have drugs that can turn off these specific shields and signals. The challenge for modern medicine is figuring out the best order to use these tools. Should a patient try one type of targeted drug first, or the other? And if a patient has already taken one type and the cancer started to grow again, will switching to the other type still work well enough to keep the disease under control for a long time?

A team of researchers across twelve hospitals in Italy set out to answer these questions by looking at the real-world experiences of ninety patients with this type of blood cancer. These patients had already been treated before and their cancer had returned or stopped responding to previous therapies. The doctors gave them a specific combination of two drugs: one that blocks the BCL-2 protein and another that helps the immune system find the cancer. Unlike older treatments that continued indefinitely, this combination was given for a fixed period of twenty-four months, after which the patients stopped taking the medication to see if their bodies could stay healthy on their own. The researchers wanted to see how long the cancer stayed away and whether the order of treatments mattered. They paid close attention to patients who had previously taken a drug that blocks the Bruton tyrosine kinase protein, as well as those who had not. They also looked at the genetic makeup of the cancer in each patient and measured how deeply the treatment had cleared the disease from the body.

The results showed that this fixed-duration approach was highly effective for most people. After following the patients for an average of forty months, the researchers found that ninety percent of the group was still free from disease progression three years after starting the treatment. Ninety-four percent of the patients were still alive at that same mark. However, the story was not the same for everyone. The researchers discovered that patients who had previously taken the Bruton tyrosine kinase inhibitor drug before starting this new combination had a slightly harder time. While ninety-seven percent of patients who had never taken that specific drug before remained free of disease progression at three years, only eighty-four percent of those who had taken it before were still doing well. This difference was statistically significant, suggesting that the history of treatment does influence the long-term outcome. The researchers noted that most of these patients had taken the previous drug for a long time before it stopped working, which implies that their cancer had become more complex and resistant over time, rather than the previous drug itself causing the issue.

The study also highlighted the importance of the cancer's genetic code. Patients whose cancer cells had a specific disruption in a gene called TP53, which normally helps control cell growth, saw much poorer results. Only sixty-four percent of these patients remained free of disease progression at three years, compared to ninety-seven percent of those without this genetic change. On the other hand, another genetic marker, known as IGHV status, did not seem to make a difference in how long the treatment worked. The researchers also looked at how deeply the treatment cleared the cancer. They measured for "measurable residual disease," which is a way of checking if even tiny, invisible traces of cancer remain after treatment is finished. Patients who achieved a state where no traces of cancer could be detected had a perfect record of staying disease-free for at least forty months. In contrast, those who still had detectable traces of cancer saw their disease return more often, with their chances of staying free of progression dropping to about forty-five percent by forty-eight months.

Safety was another key part of the picture. The treatment was generally well-tolerated, though it did require some adjustments in routine practice. About one-quarter of the patients needed to pause the medication temporarily, usually due to low blood cell counts, and a few needed their doses reduced. The researchers found that these interruptions and dose reductions did not hurt the long-term success of the treatment. The most common side effect was a drop in white blood cells, which happened in a small number of patients, but serious infections were rare. The study confirmed that this fixed-duration strategy is a viable and durable option for patients in everyday clinical settings, not just in controlled research trials. It reinforced the idea that while the treatment works well for many, the specific history of a patient's prior therapies and the genetic nature of their cancer are critical factors in predicting how long the remission will last. The findings suggest that doctors must carefully consider the sequence of treatments and the depth of the response to offer the best possible care for each individual.