Musculoskeletal pain after stopping tyrosine kinase inhibitor in patients with chronic myeloid leukemia: a questionnaire survey.

We conducted a questionnaire survey to assess the state of patients with CML after discontinuation of TKI therapy. Nine of 27 patients developed musculoskeletal pain after TKI discontinuation. One had discontinued nilotinib and eight had discontinued imatinib therapy. Median time to symptom development after discontinuation was 2 weeks. Four experienced grade 3 symptoms as per the CTCAE ver. 4.0. One had pain persisting over a period of 21 months. There was a significant difference between patients with and without symptoms as regards female gender and the probability of persistent MMR. Awareness of this withdrawal syndrome after TKI discontinuation is imperative.

Combination therapy with copanlisib and ABL tyrosine kinase inhibitors against Philadelphia chromosome-positive resistant cells.

ABL tyrosine kinase inhibitor (TKI) therapy has improved the survival of patients with Philadelphia (Ph) chromosome-positive leukemia. However, ABL TKIs cannot eradicate leukemia stem cells. Therefore, new therapeutic approaches for Ph-positive leukemia are needed. Aberrant activation of phosphoinositide 3-kinase (PI3K) signaling is important for the initiation and maintenance of human cancers. Copanlisib (BAY80-6946) is a potent inhibitor of PI3Kα and PI3K-δ. Here we investigated the efficacy of combination therapy of copanlisib with an ABL TKI (imatinib, nilotinib, or ponatinib) using BCR-ABL-positive cells. Although the effects of the ABL TKI treatment were reduced in the presence of the feeder cell line, HS-5, copanlisib inhibited cell growth. Upon combining ABL TKI and copanlisib, cell growth was reduced. Ponatinib and copanlisib combined therapy reduced tumor volume and increased survival in mouse allograft models, respectively. These results indicate that the PI3Kα and -δ inhibitors overcame the chemoprotective effects of the feeder cells and enhanced ABL TKI cytotoxicity. Thus, co-treatment with ABL TKI and copanlisib may be a powerful strategy against ABL TKI-resistant cells, including those harboring the related T315I mutation.

Anti-leukemic activity of axitinib against cells harboring the BCR-ABL T315I point mutation.

The BCR-ABL; breakpoint cluster region-Abelson point mutation T315I is resistant to ABL tyrosine kinase inhibitors. However, axitinib, a vascular endothelial growth factor receptor inhibitor, is effective against this mutation. In this study, we investigated axitinib activity against ponatinib-resistant cells and found that axitinib inhibited cellular growth and apoptosis in Ba/F3 T315I-mutant cells and T315I-mutant primary samples, but not in ponatinib-resistant Ba/F3 cells and primary samples. Thus, an alternative strategy may be required to improve the prognosis of Philadelphia-chromosome-positive leukemia patients harboring BCR-ABL point mutations.

Efficacy of the polo-like kinase inhibitor rigosertib, alone or in combination with Abelson tyrosine kinase inhibitors, against break point cluster region-c-Abelson-positive leukemia cells.

The potency of Abelson (ABL) tyrosine kinase inhibitors (TKIs) against chronic myeloid leukemia (CML) has been demonstrated. However, ABL TKI resistance can develop. In this study, we investigated the efficacy of a combination therapy including rigosertib (ON 01910.Na), a polo-like kinase (PLK) and phosphoinositide 3-kinase (PI3K) inhibitor, and ABL TKIs. A 72-h rigosertib treatment was found to inhibit cell growth, induce apoptosis, reduce phosphorylation of the breakpoint cluster region-c (BCR)-ABL and its substrate Crk-L, and increase the activities of caspase 3 and poly (ADP-ribose) polymerase (PARP). This combination therapy also exerted a synergistic inhibitory effect on Philadelphia chromosome (Ph)-positive cell proliferation and reduced the phosphorylation of BCR-ABL and Crk-L while increasing that of cleaved PARP and the H2A.X histone. Rigosertib also potently inhibited the growth of ABL TKI-resistant cells, and cotreatment with ABL TKIs and rigosertib induced higher cytotoxicity. These results indicate that rigosertib treatment may be a powerful strategy against ABL TKI-resistant cells and could enhance the cytotoxic effects of ABL TKIs.

Estimation of cardiac left ventricular ejection fraction in transfusional cardiac iron overload by R2* magnetic resonance.

Cardiac dysfunction due to transfusional iron overload is one of the most critical complications for patients with transfusion-dependent hematological disorders. Clinical parameters such as total red blood cell (RBC) transfusion units and serum ferritin level are usually considered as indicators for initiation of iron chelation therapy. We used MRI-T2*, MRI-R2* values, and left ventricular ejection fraction in 19 adult patients with blood transfusion-dependent hematological disorders without consecutive oral iron chelation therapy, and propose possible formulae of cardiac function using known parameters, such as total RBC transfusion units and serum ferritin levels. We found a positive correlation in all patients between both R2* values (reciprocal values of T2*) and serum ferritin levels (r = 0.81) and also total RBC transfusion volume (r = 0.90), but not when we analyzed subgroups of patients whose T2* values were over 30 ms (0.52). From the formulae of the R2*, we concluded that approximately 50 Japanese units or 2,900 pmol/L ferritin might be the cutoff value indicating possible future cardiac dysfunction.