The effects of hydroxychloroquine and imatinib on treatment outcomes in patients with chronic myeloid leukemia

The study evaluated the combined effects of imatinib (IM; Gleevec) and hydroxychloroquine (HCQ; Plaquenil) in patients with chronic-phase chronic myeloid leukemia (CP-CML) and residual leukemic stem cells. The authors found that this combination safely and moderately improved treatment outcomes in such patients compared to IM alone.

CP-CML is caused by cancerous defects in an enzyme named BCR-ABL1. After a fisrt treatment, stem cells containing leukemic BCR-ABL1 are sometimes left in the body of patients with no cancerous genetic defects. This condition is called residual disease. It causes leukemia’s return in acute form.

IM is an approved treatment that kills leukemic cells by inhibiting BCR-ABL1. The drug HCQ increased the effects of IM on leukemic cells isolated from patients with CML. However, it is unclear if combining IM and HCQ results in better treatment outcomes in patients with CP-CML and residual disease.

The study included 62 adult patients with CP-CML who were already treated with IM. All patients had major cytogenetic remission (MCyR). MCyR is achieved when no cell with cancerous genes are left in patients’ bodies. 30 patients received IM alone and 32 received IM/HCQ combined. They were followed up for 24 months.

Treatment was considered successful when BCR-ABL1 levels in stem cells decreased by more than 3 times after 12 months of therapy. The success rate was slightly higher in the IM/HCQ group compared to IM alone after 12 months (by 1.2%).

Major molecular response (MMR) is achieved when 1 in 1000 blood cells is left with cancerous BCR-ABL1. 66.7% of patients with IM and 71.9% of patients with IM/HCQ experienced MMR after 12 months. However, after 24 months of therapy, treatment success was 20.8% higher in the IM/HCQ group compared to IM alone.

No patients experienced disease worsening in 24 months. IM/HCQ treatment was well tolerated among all patients. Diarrhea was more common in the IM/HCQ group. 

The study concluded that IM/HCQ was safe and caused moderate improvements in treatment success compared to IM alone in patients with CP-CML and residual disease. 

This study had a small number of participants and short follow-up period. Larger studies are needed.