azd-6244 and Multiple-Myeloma

AZD6244 is a MEK1/2 inhibitor with significant preclinical activity in multiple myeloma cells. This phase II study used a two-stage Simon design to determine the AZD6244 response rate in patients with relapsed or refractory multiple myeloma.. AZD6244 (75 mg) was administered orally, twice a day, continuously for 28-day cycles. Response was evaluated after three cycles.. Thirty-six patients received therapy. The median age was 65 years (range: 43-81) and the median number of prior therapies was 5 (range: 2-11). The most common grade 3 and 4 toxicities included anemia, neutropenia, thrombocytopenia, diarrhea, and fatigue. Three deaths occurred possibly related to AZD6244 (2 due to sepsis, 1 due to acute kidney injury). After AZD6244 discontinuation, three additional deaths occurred due to disease progression. The response rate (CR + PR) was 5.6% with a mean duration of response of 4.95 months and median progression-free survival time of 3.52 months. One patient had a very good partial response (VGPR), 1 patient had a partial response, 17 patients had stable disease, 13 patients had progressive disease, and 4 patients could not be assessed for response. Pharmacodynamic studies revealed variable effects on bone marrow CD138(+) cell MEK1/2 and ERK1/2 phosphorylation. The best clinical response, a prolonged VGPR, occurred in a patient with an MMSET translocation.. Single-agent AZD6244 was tolerable and had minimal activity in this heavily pretreated population.

Topics: Adult; Aged; Aged, 80 and over; Benzimidazoles; Disease-Free Survival; Female; Humans; Kaplan-Meier Estimate; Male; MAP Kinase Kinase Kinases; Middle Aged; Multiple Myeloma; Neoplasm Recurrence, Local; Proto-Oncogene Proteins p21(ras)

Activation of the extracellular signal-regulated kinase1/2 (ERK1/2) signaling cascade mediates human multiple myeloma (MM) growth and survival triggered by cytokines and adhesion to bone marrow stromal cells (BMSCs). Here, we examined the effect of AZD6244 (ARRY-142886), a novel and specific MEK1/2 inhibitor, on human MM cell growth in the bone marrow (BM) milieu. AZD6244 blocks constitutive and cytokine-stimulated ERK1/2 phosphorylation and inhibits proliferation and survival of human MM cell lines and patient MM cells, regardless of sensitivity to conventional chemotherapy. Importantly, AZD6244 (200 nM) induces apoptosis in patient MM cells, even in the presence of exogenous interleukin-6 or BMSCs associated with triggering of caspase 3 activity. AZD6244 sensitizes MM cells to both conventional (dexamethasone) and novel (perifosine, lenalidomide, and bortezomib) therapies. AZD6244 down-regulates the expression/secretion of osteoclast (OC)-activating factors from MM cells and inhibits in vitro differentiation of MM patient PBMCs to OCs induced by ligand for receptor activator of NF-kappaB (RANKL) and macrophage-colony stimulating factor (M-CSF). Finally, AZD6244 inhibits tumor growth and prolongs survival in vivo in a human plasmacytoma xenograft model. Taken together, these results show that AZD6244 targets both MM cells and OCs in the BM microenvironment, providing the preclinical framework for clinical trials to improve patient outcome in MM.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Benzimidazoles; Bone Marrow Cells; Boronic Acids; Bortezomib; Cell Adhesion; Cell Differentiation; Cell Proliferation; Cell Survival; Cytotoxins; Dexamethasone; Dose-Response Relationship, Drug; Interleukin-6; Lenalidomide; Ligands; Macrophage Colony-Stimulating Factor; MAP Kinase Kinase 1; MAP Kinase Kinase 2; MAP Kinase Signaling System; Mice; Mice, SCID; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Multiple Myeloma; Neoplasm Transplantation; Osteoclasts; Phosphorylcholine; Pyrazines; RANK Ligand; Stromal Cells; Thalidomide; Transplantation, Heterologous; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

The development of resistance to therapy is unavoidable in the history of multiple myeloma patients. Therefore, the study of its characteristics and mechanisms is critical in the search for novel therapeutic approaches to overcome it. This effort is hampered by the absence of appropriate preclinical models, especially those mimicking acquired resistance. Here we present an in vivo model of acquired resistance based on the continuous treatment of mice bearing subcutaneous MM1S plasmacytomas. Xenografts acquired resistance to two generations of immunomodulatory drugs (IMiDs; lenalidomide and pomalidomide) in combination with dexamethasone, that was reversible after a wash-out period. Furthermore, lenalidomide-dexamethasone (LD) or pomalidomide-dexamethasone (PD) did not display cross-resistance, which could be due to the differential requirements of the key target Cereblon and its substrates Aiolos and Ikaros observed in cells resistant to each combination. Differential gene expression profiles of LD and PD could also explain the absence of cross-resistance. Onset of resistance to both combinations was accompanied by upregulation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK pathway and addition of selumetinib, a small-molecule MEK inhibitor, could resensitize resistant cells. Our results provide insights into the mechanisms of acquired resistance to LD and PD combinations and offer possible therapeutic approaches to addressing IMiD resistance in the clinic.

Topics: Adaptor Proteins, Signal Transducing; Animals; Antineoplastic Agents; Apoptosis; Benzimidazoles; Cell Line, Tumor; Dexamethasone; Disease Models, Animal; Drug Resistance, Neoplasm; Drug Therapy, Combination; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation, Neoplastic; Humans; Ikaros Transcription Factor; Lenalidomide; Mice; Multiple Myeloma; Neoplasm Transplantation; Nerve Tissue Proteins; Plasmacytoma; Signal Transduction; Thalidomide; Trans-Activators

Heat shock protein (HSP)90 inhibitors have shown significant anti-tumor activities in preclinical settings in both solid and hematological tumors. We previously reported that the novel, orally available HSP90α/β inhibitor TAS-116 shows significant anti-MM activities. In this study, we further examined the combination effect of TAS-116 with a RAS-RAF-MEK-ERK signaling pathway inhibitor in RAS- or BRAF-mutated MM cell lines. TAS-116 monotherapy significantly inhibited growth of RAS-mutated MM cell lines and was associated with decreased expression of downstream target proteins of the RAS-RAF-MEK-ERK signaling pathway. Moreover, TAS-116 showed synergistic growth inhibitory effects with the farnesyltransferase inhibitor tipifarnib, the BRAF inhibitor dabrafenib, and the MEK inhibitor selumetinib. Importantly, treatment with these inhibitors paradoxically enhanced p-C-Raf, p-MEK, and p-ERK activity, which was abrogated by TAS-116. TAS-116 also enhanced dabrafenib-induced MM cytotoxicity associated with mitochondrial damage-induced apoptosis, even in the BRAF-mutated U266 MM cell line. This enhanced apoptosis in RAS-mutated MM triggered by combination treatment was observed even in the presence of bone marrow stromal cells. Taken together, our results provide the rationale for novel combination treatment with HSP90α/β inhibitor and RAS-RAF-MEK-ERK signaling pathway inhibitors to improve outcomes in patients with in RAS- or BRAF-mutated MM.

Topics: Apoptosis; Benzamides; Benzimidazoles; Bortezomib; Cell Line, Tumor; Doxorubicin; Drug Screening Assays, Antitumor; Genes, ras; HSP90 Heat-Shock Proteins; Humans; Imidazoles; MAP Kinase Signaling System; Multiple Myeloma; Oximes; Proto-Oncogene Proteins B-raf; Pyrazoles

Effects of Chk1 and MEK1/2 inhibition were investigated in cytokinetically quiescent multiple myeloma (MM) and primary CD138(+) cells. Coexposure to the Chk1 and MEK1/2 inhibitors AZD7762 and selumetinib (AZD6244) robustly induced apoptosis in various MM cells and CD138(+) primary samples, but spared normal CD138(-) and CD34(+) cells. Furthermore, Chk1/MEK1/2 inhibitor treatment of asynchronized cells induced G(0)/G(1) arrest and increased apoptosis in all cell-cycle phases, including G(0)/G(1). To determine whether this regimen is active against quiescent G(0)/G(1) MM cells, cells were cultured in low-serum medium to enrich the G(0)/G(1) population. G(0)/G(1)-enriched cells exhibited diminished sensitivity to conventional agents (eg, Taxol and VP-16) but significantly increased susceptibility to Chk1 ± MEK1/2 inhibitors or Chk1 shRNA knock-down. These events were associated with increased γH2A.X expression/foci formation and Bim up-regulation, whereas Bim shRNA knock-down markedly attenuated lethality. Immunofluorescent analysis of G(0)/G(1)-enriched or primary MM cells demonstrated colocalization of activated caspase-3 and the quiescent (G(0)) marker statin, a nuclear envelope protein. Finally, Chk1/MEK1/2 inhibition increased cell death in the Hoechst-positive (Hst(+)), low pyronin Y (PY)-staining (2N Hst(+)/PY(-)) G(0) population and in sorted small side-population (SSP) MM cells. These findings provide evidence that cytokinetically quiescent MM cells are highly susceptible to simultaneous Chk1 and MEK1/2 inhibition.

Topics: Apoptosis; Benzimidazoles; Cell Line, Tumor; Checkpoint Kinase 1; DNA Damage; G1 Phase; Humans; Interleukin-6; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Multiple Myeloma; Protein Kinase Inhibitors; Protein Kinases; Resting Phase, Cell Cycle; Syndecan-1; Thiophenes; Urea

Osteolytic bone disease in multiple myeloma (MM) is associated with upregulation of osteoclast (OCL) activity and constitutive inhibition of osteoblast function. The extracellular signal-regulated kinase 1/2 (ERK1/2) pathway mediates OCL differentiation and maturation. We hypothesized that inhibition of ERK1/2 could prevent OCL differentiation and downregulate OCL function. It was found that AZD6244, a mitogen-activated or extracellular signal-regulated protein kinase (MEK) inhibitor, blocked OCL differentiation and formation in a dose-dependent manner, evidenced by decreased alphaVbeta3-integrin expression and tartrate-resistant acid phosphatase positive (TRAP+) cells. Functional dentine disc cultures showed inhibition of OCL-induced bone resorption by AZD6244. Major MM growth and survival factors produced by OCLs including B-cell activation factor (BAFF) and a proliferation-inducing ligand (APRIL), as well as macrophage inflammatory protein (MIP-1alpha), which mediates OCL differentiation and MM, were also significantly inhibited by AZD6244. In addition to ERK inhibition, NFATc1 (nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 1) and c-fos were both downregulated, suggesting that AZD6244 targets a later stage of OCL differentiation. These results indicate that AZD6244 inhibits OCL differentiation, formation and bone resorption, thereby abrogating paracrine MM cell survival in the bone marrow microenvironment. The present study therefore provides a preclinical rationale for the evaluation of AZD6244 as a potential new therapy for patients with MM.

Topics: Acid Phosphatase; Benzimidazoles; Biomarkers; Blotting, Western; Bone Resorption; Cell Differentiation; Chemokine CCL3; Chemokine CCL4; Cytokines; Depression, Chemical; Dose-Response Relationship, Drug; Enzyme Inhibitors; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Gene Expression; Humans; Integrin alphaVbeta3; Isoenzymes; Macrophage Colony-Stimulating Factor; Macrophage Inflammatory Proteins; Mitogen-Activated Protein Kinases; Multiple Myeloma; Osteoclasts; RANK Ligand; Tartrate-Resistant Acid Phosphatase; Transcription Factors; Tumor Cells, Cultured