For most cancers, especially solid tumors, chemotherapy is a go-to treatment. But as powerful as it is, it’s toxic and comes with serious side effects. It’s an active time for cancer researchers who are trying, with great success, to develop new ways of treating cancer that don’t involve chemo. They’re also making progress in identifying those cancers that don’t need chemo—or won’t respond to it.

MORE: No More Chemo: Doctors Say It’s Not So Far-Fetched

In a new study, published in the New England Journal of Medicine, scientists led by MD Anderson Cancer Center’s Dr. Jan Burger find that some people with chronic lymphocytic leukemia (CLL), the most common kind of leukemia, fared much better on an anticancer drug called ibrutinib compared with those who were given standard chemotherapy. The cancers progressed more slowly in people who were given ibrutinib and they had a much better response to the drug, compared with those on the chemo.

“The big message is that there is a major difference between the two groups,” says Burger, who presented his findings at the annual meeting of the American Society of Hematology. “The ibrutinib patients are doing much better in every aspect in terms of their response rates.” After two years, 98% of the people taking ibrutinib were still alive, compared to 85% of those who were treated with chemo. (All began the study when they started showing signs of disease.)

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Other studies have explored whether chemotherapy can be skipped, but most of those have focused on CLL patients who haven’t responded to standard chemotherapy. Burger’s study tested ibrutinib in people as a first-line treatment. That could prove to be very expensive, however. A recent paper analyzed the hypothetical 10-year cost of ibrutinib as a first-line therapy compared with the current standard chemo drugs and for newly diagnosed CLL patients, concluded that while ibrutinib is a major treatment advance, it will “dramatically increase individual out-of-pocket and societal costs of caring for patients with CLL.”

Ibrutinib is approved to treat several cancers, including CLL, but only in patients who had failed to respond on other therapies.

It joins a growing list of targeted-therapy drugs that home in on tumor cells specifically (whereas chemo kills cells both healthy and sick). Such elegant and specific strategies are becoming much more common in treating many types of cancer.

At MD Anderson, he says that more of these targeted agents are being considered as first line treatments instead of chemotherapy because they often have fewer side effects and help patients to live more normal lives. And while the drug may cost more than standard chemotherapy, chemotherapy is associated with complications that may require additional care or even hospitalization that can increase total costs of the therapy. So while the results are promising, more studies such as this one that support the effectiveness of the non-chemotherapy treatments — as well as their cost effectiveness — are needed before ibrutinib can replace chemo for CLL patients.

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