Synergistic activity of nilotinib and established chemotherapeutic drugs in imatinib-sensitive and -resistant BCR-ABL-positive cells

TKI rotation-induced persistent deep molecular response in multi-resistant blast crisis of Ph+ CML

In chronic myeloid leukemia (CML) resistance against one or more BCR-ABL1 tyrosine kinase inhibitors (TKI) remains a clinical challenge. Preclinical data suggest that TKI combinations may overcome resistance. We report on a heavily pre-treated 78 year-old female patient with CML who developed multi-resistant blast crisis with bone marrow fibrosis and a Ph- clone. Treatment with ponatinib resulted in blast cell clearance, decrease in fibrosis, and disappearance of BCR-ABL1, but also in severe thrombocytopenia with bleedings requiring platelet transfusions. We therefore switched from ponatinib to bosutinib. During bosutinib, platelet counts recovered. However, after 6 months, BCR-ABL1 mRNA levels increased to > 1%. Therefore, we ´switched back´ to ponatinib, and this was again followed by disappearance of BCR-ABL1 and a decrease in platelets. During the next 2 years, we applied ponatinib and bosutinib in continuous rotation-cycles and added hydroxyurea in order to suppress all sub-clones and to balance between efficacy and potential side effects following the principle of personalized medicine. With this approach the patient remained in complete molecular response and reached normal blood counts and a normal quality of life without vascular or other side effects. In conclusion, TKI rotation is a novel potent approach to suppress multiple resistant sub-clones and to balance between clinical efficacy and side effects in patients with advanced CML. Clinical trials are now warranted to show that TKI-rotation is in general safe and effective in these patients.

Low serum vitamin D levels are associated with shorter survival after first-line azacitidine treatment in patients with myelodysplastic syndrome and secondary oligoblastic acute myeloid leukemia

BACKGROUND & AIMS

Azacitidine (AZA) therapy has become the recommended first-line treatment for patients with high-risk myelodysplastic syndromes (MDS) and oligoblastic (<30% bone marrow blasts) acute myeloid leukemia (AML). However, improvement of the efficacy of AZA treatment remains a challenge. We retrospectively tested the hypothesis that VitD levels (25-hydroxyvitamin D3) prior to start of first-line AZA therapy are predictive of overall survival (OS) in patients diagnosed with MDS and secondary oligoblastic AML. Furthermore, the antiproliferative effects of AZA in combination with 25-hydroxyvitamin D3 and 1α,25-dihydroxyvitamin D3 were investigated in vitro.

METHODS

A total of 58 patients treated at our center between 2006 and 2014 were analyzed. Serum levels of VitD were quantified using a standard, commercially available 25-hydroxyvitamin D3 chemiluminescent immunoassay. Effects on cell proliferation were assessed using tetrazolium-based MTT assays.

RESULTS

Median serum VitD level prior to AZA treatment was 32.8 nM (range 11.0-101.5 nM). Patient, disease and treatment characteristics did not differ significantly between the low (≤32.8 nM; n = 29) and high (>32.8 nM; n = 29) VitD group. Estimated probability of 2-year OS in the low versus high VitD group was 14% versus 40% (P < 0.05). In multivariable analysis with OS as endpoint, adverse cytogenetics (HR 2.66, P = 0.03) and VitD (per 10 nM decrease, HR 1.68, P = 0.02) were independent predictors of worse survival. In-vitro treatment of myeloid cell lines with AZA in combination with VitD produced synergistic and additive antiproliferative effects. Addition of nanomolar VitD concentrations to AZA resulted in potentiation of AZA activity. Conversely, combination with the VitD antagonist TEI-9647 resulted in inhibition of AZA activity.

CONCLUSIONS

Our study suggests that higher VitD levels were associated with a survival advantage following first-line AZA therapy. Enhanced cytotoxic effects upon combination treatment may contribute to the observed clinical effects. VitD repletion/supplementation during AZA treatment should be explored.

Effects of Jak2 type 1 inhibitors NVP-BSK805 and NVP-BVB808 on Jak2 mutation-positive and Bcr-Abl-positive cell lines

Janus kinases are critical components of signaling pathways that regulate hematopoiesis. Mutations of the non-receptor tyrosine kinase JAK2 are found in many BCR-ABL-negative myeloproliferative neoplasms. Preclinical results support that JAK2 inhibitors could show efficacy in treating chronic myeloproliferative neoplasms. JAK2 has also been postulated to play a role in BCR-ABL signal transduction. Therefore, inhibitors of JAK2 kinases are turning into therapeutic strategies for treatment of chronic myelogenous leukemia (CML). In this study, the effects of two novel JAK2 inhibitors, NVP-BSK805 and NVP-BVB808, have been investigated in cell lines expressing either BCR-ABL or mutant JAK2. Possible synergies between NVP-BSK805/NVP-BVB808 and the kinase inhibitors imatinib and nilotinib were assessed. Proliferation and apoptosis tests with both substances showed response in the following cell lines: CHRF-288-11, SET-2 and UKE-1. All BCR-ABL-positive cell lines showed some reduction in proliferation, but with half-maximal growth-inhibitory values >1 µM. Combination of the JAK2 inhibitors with imatinib and nilotinib showed no significant additive or synergistic effects, although all BCR-ABL-positive cell lines responded well to both CML therapeutic agents. Interestingly, it seemed that the combination of imatinib with NVP-BSK805 had a protective effect on the cells. Combination treatment with nilotinib did not show this effect.