Impact of metformin on tyrosine kinase inhibitor response in chronic myeloid leukemia.

OBJECTIVE: Oral tyrosine kinase inhibitors (TKIs) are first line therapy for chronic myeloid leukemia (CML). A complete cytogenetic response (CCyR) correlates with increased overall survival, however only 66%-88% of patients achieve CCyR after one year of TKI treatment. Because TKI therapy alone cannot eliminate CML stem cells, strategies aimed at achieving faster and deeper responses are needed to improve long-term survival. Metformin is a widely prescribed glucose-lowering agent for patients with diabetes and in preclinical studies, has been shown to suppress cell viability, induce apoptosis, and downregulate the mTORC1 signaling pathway in imatinib resistant CML cell lines (K562R). This study aims to investigate the utility of metformin added to TKI therapy in patients with CML. DATA SOURCES: An observational study at an academic medical center (Salt Lake City, UT) was performed for adults with newly diagnosed, chronic-phase CML to evaluate attainment of CCyR from TKI therapy with or without concomitant metformin use. Descriptive analyses were used to describe baseline characteristics and attainment of response to TKI therapy. DATA SUMMARY: Fifty-nine patients were evaluated. One hundred percent (5 of 5) in the metformin group and 73.6% (39 of 54) in the non-metformin group achieved CCyR. Approximately 20% of patients in both groups relapsed (defined by a loss of CCyR during study) after a median 34.5 months of follow-up. CONCLUSIONS: Future research is warranted to validate these findings and determine the utility of metformin added to TKI therapy.

Real-world experience with elective discontinuation of PD-1 inhibitors at 1 year in patients with metastatic melanoma.

BACKGROUND: Randomized trials evaluating programmed cell death protein 1 (PD-1) inhibitors in metastatic melanoma either permitted treatment for 2 years (pembrolizumab) or more (nivolumab). The optimal duration of therapy is currently unknown due to limited data, and shorter therapies may be effective. METHODS: Data of patients with metastatic cutaneous melanoma treated with single-agent PD-1 inhibitors at Huntsman Cancer Institute from January 1, 2015, to December 31, 2018, was reviewed to identify a continuous series of patients who made the joint decision with their provider to electively discontinue therapy at 1 year (>6 months and <18 months) in the setting of ongoing treatment response or disease stability. Patients were excluded if they received PD-1 inhibitors with other systemic therapy, had prior exposure to PD-1 therapy, or discontinued treatment due to disease progression or immune-related adverse event. Best objective response (BOR) per RECIST V.1.1 at treatment discontinuation, progression-free survival (PFS), and retreatment characteristics was analyzed. RESULTS: Of 480 patients who received PD-1 inhibitors, 52 met the inclusion criteria. The median treatment duration from first to the last dose was 11.1 months (95% CI 10.5 to 11.4). BOR was complete response in 13 (25%), partial response in 28 (53.8%), and stable disease in 11 (21.2%) patients. After a median follow-up of 20.5 months (range 3-49.2) from treatment discontinuation, 39 (75%) patients remained without disease progression, while 13 (25%) had progression (median PFS 3.9 months; range 0.7-30.9). On multivariable analysis, younger age, history of brain metastasis, and higher lactate dehydrogenase at the time of anti-PD-1 discontinuation were associated with recurrence. Patients with recurrent melanoma were managed with localized treatment, anti-PD-1 therapies, and BRAF-MEK inhibitors. All patients except one were alive at data cutoff. CONCLUSION: In this large real-world, observational cohort study, the majority of patients with metastatic melanoma after 1 year of anti-PD-1 therapy remained without progression on long-term follow-up. The risk of disease progression even in patients with residual disease on imaging was low. After prospective validation, elective PD-1 discontinuation at 1 year may reduce financial and immunotherapy-related toxicity without sacrificing outcomes.