Phase I trial of bortezomib during maintenance phase after high dose melphalan and autologous stem cell transplantation in patients with multiple myeloma

STMN1 promotes cell malignancy and bortezomib resistance of multiple myeloma cell lines via PI3K/AKT signaling

BACKGROUND

This study investigates the biological functions of Stathmin1 (STMN1) involving drug resistance and cell proliferation in multiple myeloma (MM) and its related mechanisms.

METHODS

Bone marrow aspirates were collected from 20 MM patients, and the bone marrow mononuclear cells (BMMCs) were separated by Ficoll-Hypaque density gradient centrifugation. Blood samples of 20 patients with monoclonal gammopathy of undetermined significance (MGUS) and 20 healthy donors were collected. Normal plasma cells sorted from the peripheral blood of MGUS patients and healthy subject as controls. Two bortezomib (BTZ)-resistant MM cell lines were established, namely NCI-H929/BTZ and KM3/BTZ cells, and then transfected with lentiviruses packaging sh-STMN1 to knock down STMN1 level in BTZ-resistant cells. Expression of STMN1 was assessed by RT-qPCR and western blotting. CCK-8 assays were performed to assess 50% growth inhibition (IC50) values. Green fluorescent protein in BTZ-resistant cells infected with lentiviruses was observed by fluorescence microscopy. Cell viability, proliferation, cell cycle, and apoptosis were evaluated through MTT assays, colony formation assays, flow cytometry analyses, and TUNEL staining.

RESULTS

STMN1 was upregulated in MM cells and bone marrow aspirates of MM patients. Additionally, STMN1 depletion attenuated BTZ resistance in MM cells. Moreover, downregulation of STMN1 limited the malignant phenotypes of BTZ-resistant cells. Mechanistically, the PI3K/Akt signaling was inactivated by STMN1 downregulation in BTZ-resistant cells.

CONCLUSION

STMN1 silencing inhibits cell proliferation and BTZ resistance in MM by inactivating the PI3K/Akt signaling.

Histone deacetylase inhibitor NaBut suppresses cell proliferation and induces apoptosis by targeting p21 in multiple myeloma

Multiple myeloma (MM) is an extremely serious hematological malignancy that remains incurable due to chemotherapy resistance. Epigenetic regulation is closely associated with progression of MM. Histone deacetylase inhibitor NaBut functions in various physiologic processes, including inflammation and differentiation. Its' possible roles in MM progression have not been explored. In this report, NaBut decreased survival of several human MM cell lines in a dose- and time-dependent manner. NaBut could also lead to cell cycle arrest at the G2/M phase in a dose-dependent manner. NaBut inhibited bortezomib-resistant cell proliferation in dose- and time-dependent manners, and NaBut was likely to induce partly bortezomib-resistant MM cell death. Moreover, NaBut induced MM cell apoptosis via transcriptional activation of p21. Overall, our results implicate NaBut as a potential therapeutic drug for MM.

Exposure-safety-efficacy analysis of single-agent ixazomib, an oral proteasome inhibitor, in relapsed/refractory multiple myeloma: dose selection for a phase 3 maintenance study

Background Ixazomib is the first oral, small molecule proteasome inhibitor to reach phase 3 trials. The current analysis characterized the exposure-safety and exposure-efficacy relationships of ixazomib in patients with relapsed/refractory multiple myeloma (MM) with a purpose of recommending an approach to ixazomib dosing for maintenance therapy. Methods Logistic regression was used to investigate relationships between ixazomib plasma exposure (area under the curve/day; derived from individual apparent clearance values from a published population pharmacokinetic analysis) and safety/efficacy outcomes (hematologic [grade ≥ 3 vs ≤ 2] or non-hematologic [grade ≥ 2 vs ≤ 1] adverse events [AEs], and clinical benefit [≥stable disease vs progressive disease]) using phase 1 data in relapsed/refractory MM (NCT00963820; N = 44). Results Significant relationships to ixazomib exposure were observed for five AEs (neutropenia, thrombocytopenia, rash, fatigue, and diarrhea) and clinical benefit (p < 0.05). Dose–response relationships indicated a favorable benefit/risk ratio at 3 mg and 4 mg weekly, which are below the maximum tolerated dose of 5.5 mg. At 3 mg, the model predicted that: 37 % of patients will achieve clinical benefit; incidence of grade ≥ 3 neutropenia and thrombocytopenia will be 10 % and 23 %, respectively; and incidence of grade ≥ 2 rash, fatigue, and diarrhea will be 8 %, 19 %, and 19 %, respectively. Conclusions Based on the findings, patients in the phase 3 maintenance trial will initiate ixazomib at a once-weekly dose of 3 mg, increasing to 4 mg if acceptable tolerability after 4 cycles, to provide maximum clinical benefit balanced with adequate tolerability.

A multicenter clinical study to determine the feasible initial dose of lenalidomide for maintenance therapy in patients with multiple myeloma following autologous peripheral blood stem-cell transplantation

Maintenance therapy with lenalidomide (LEN) for patients with multiple myeloma (MM) following autologous peripheral blood stem cell transplantation (auto-PBSCT) may be a promising option for preventing relapse or disease progression. However, the recommended dose of LEN has yet to be firmly established. We herein report the results of a multicenter clinical study for determining the feasible initial dose (FID) of LEN. In this trial, a total of 11 patients who achieved a very good partial response or complete response following auto-PBSCT were enrolled from five transplant centers in Japan. Three dose levels of LEN (level 0, 5 mg; level 1, 10 mg; and level 2,:15 mg) were tested in this study. FID was defined as the maximum estimated dose at which 70% of the patients could receive maintenance therapy for 12 weeks without any serious adverse events or disease progression. Using a continual reassessment method, 6 patients were assigned to level 0 and the remaining 5 patients were assigned to level 1. All 6 patients (100%) at level 0, but only 2 patients (40%) at level 1, completed 12 weeks of administration with their assigned dose of LEN. The results of our study demonstrated that, although 5 mg of LEN was acceptable in terms of safety, 7.5 mg of LEN may also be an acceptable FID.