CML rooted in chromosome swap
It’s not clear exactly what causes CML, although the Mayo Clinic says most cases are linked to an abnormal, extra-short “Philadelphia chromosome,” created when two chromosomes swap material. This happens after birth.
Mr. Fahnestock thinks he happened to develop a random mutation. He also wonders if his work stints in the former Soviet Union in Vladivostok, “where the Soviet nuclear submarine fleet was decomposing,” and in Kiev, Ukraine, “which is not all that far from Chernobyl,” may be responsible.
Most patients, like Mr. Fahnestock, are men. Males will account for about 5,190 of the cases diagnosed in 2023, according to the American Cancer Society, compared to 3,740 in females.
Mr. Fahnestock’s CML diagnosis came at a fairly young age, when he was in his 40s. The average patient is diagnosed at 64. But it’s not unusual that he experienced no apparent symptoms when the cancer was found. In fact, that’s the norm.
Most patients with the disease – which is diagnosed in about 8,900 patients in the United States each year – are asymptomatic or have mild symptoms, Dr. Lai said. Their disease is discovered when “an elevated white count is found on routine blood work,” she said.
“The other group of patients typically present with very elevated white blood cell counts and splenomegaly with symptoms of fatigue and other constitutional symptoms. When the WBC count is very high, it is important to rule out transformation to accelerated or blast phase and also rule out an acute leukemia.”
Polymerase chain reaction is an especially important test during diagnosis, Dr. Atallah said, since it provides baseline data about the cancer that can be tracked.
TKIs: Mainstay of treatment
Four drugs are FDA approved for initial treatment of CML: imatinib (Gleevec), the second-generation TKIs dasatinib (Sprycel) and the third-generation TKI nilotinib (Tasigna). The third-generation TKIs bosutinib (Bosulif) and ponatinib (Iclusig) are approved for use as first-line treatments for patients who cannot tolerate the other drugs or are resistant to them.
The first-in-class drug asciminib (Scemblix), approved by the FDA in 2021, is a third-line drug for patients who failed treatment with two other TKIs and certain patients with the T315I mutation.
Dr. Lai said that it’s crucial to avoid side effects as much as possible “since the goal is for patients to be compliant and take the pill every day and not miss doses.” In younger patients, “I typically choose a second-generation TKI as my first choice, since there is a higher likelihood of getting into a deep molecular remission more quickly. If treatment-free remission is something a patient is interested in, a second-generation TKI is more likely to make this happen.”
According to Dr. Atallah, about half of patients end up using more than one drug because their initial choices either don’t work or cause intolerable side effects. Nevertheless, Dr. Lai noted: “Overall, patients do extremely well if compliant with their medication.”
Exceptions include the noncompliant and patients with more aggressive disease, like an accelerated or a blast phase, she said. For the latter patients, “allogenic bone marrow transplant should be considered once the patient is in remission.”
