Dasatinib (BMS-354825) pharmacokinetics correlate with pSRC pharmacodynamics in phase I studies of patients with cancer (CA180002, CA180003)

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 3046-3046 ◽  
Author(s):  
F. R. Luo ◽  
F. R. Luo ◽  
Y. Barrett ◽  
P. Ji ◽  
P. Holly ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Solid Tumors ◽  
Kinase Activity ◽  
Mononuclear Cells ◽  
Maximal Inhibition ◽  
Peripheral Blood Mononuclear ◽  
First Order ◽  
Patients With Cancer ◽  
Clinical Responses ◽  
Dose Dependent

3046 Background: Dasatinib - an inhibitor of several oncologenic kinases including BCR-ABL and SRC - has demonstrated efficacy in CML and Ph+ ALL, and is being evaluated in patients with solid tumors. Studies CA180–002, and CA180–003 were multiple ascending dose studies of dasatinib in patients with refractory Ph+ leukemia, and solid tumors, respectively. We have analyzed the preliminary results of pharmacokinetics (PK) and pharmacodynamic (PD) biomarker phospho-SRC (pSRC) combined across the CA180002 and CA180003 studies. Methods: Dasatinib was administered orally at doses of 15 - 180 mg QD or 25 - 160 mg BID. Dasatinib PK was determined by LC MS/MS. The level of phospho-SRC in peripheral blood mononuclear cells (PBMCs) was determined by an ELISA and was used as a surrogate biomarker of the level of kinase activity of the SRC family members. PK-PD modeling was performed using a two-compartment PK model with first-order absorption kinetics and an indirect inhibitory Emax model as the PD model. Results: On the BID regimen, pSRC inhibition was approximately dose-dependent across the dosing range. Inhibition also appeared to be directly correlated with dasatinib plasma concentration, with maximal inhibition achieved at ∼2.5 hr. Based on PK-PD modeling, the estimated EC50 (the plasma concentration required to achieve 50% inhibition of pSRC) is 14.4 ng/mL. Conclusions: SRC family kinase activity is substantially inhibited at the exposures of dasatinib achieved to date. The optimal regimens of dasatinib to achieve both target inhibition and solid tumors efficacy will be determined based on biomarkers, clinical responses, and toxicity profiles. [Table: see text]

Phase I pharmacokinetic (PK) and pharmacodynamic (PD) study of 17-Allylamino-17-demethoxygeldanamycin (17AAG) in children with solid tumors

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 9022-9022 ◽  
Author(s):  
R. Bagatell ◽  
L. Gore ◽  
M. Egorin ◽  
R. Ho ◽  
N. Boucher ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Phase I ◽  
Linear Relationship ◽  
Solid Tumors ◽  
Mononuclear Cells ◽  
Heat Shock Protein 90 ◽  
Peripheral Blood Mononuclear ◽  
Associated Proteins ◽  
Grade 3 ◽  
Benzoquinone Ansamycin

9022 Background: 17AAG is a benzoquinone ansamycin that binds to heat shock protein 90 (Hsp90) and alters levels of cancer-associated proteins that are regulated by Hsp90. 17AAG has been well-tolerated in adults, but has not previously been administered to children. Methods: A Phase I study of 17AAG was initiated to define the maximally tolerated dose and toxicity profile of this drug in children. PK and PD were also studied. Cohorts of 3–6 patients with recurrent or refractory solid tumors were treated every 21 days with escalating doses of 17AAG twice weekly for two weeks. Plasma PK of 17AAG and its major metabolite, 17AG, were measured on day 1 by HPLC. Changes in levels of the inducible isoform of Hsp70 were assessed by Western blot using peripheral blood mononuclear cells (PBMCs) obtained 24 h after the 17AAG infusion. Actin was measured for comparison. Because 17AAG is a substrate for CYP3A4/5 and MDR1, pharmacogenetic analyses have been undertaken to determine if genotypes including CYP3A4*1B, CYP3A5*3, and MDR1 G2677T/A and C3435T influence 17AAG disposition. Results: 12 pts (median age 11 years, range 5–18) with neuroblastoma (5), osteosarcoma (4), Ewing’s family tumors (2), and desmoplastic small round cell tumor (1) have been treated with 17AAG. An MTD has yet to be defined though one dose limiting toxicity (Grade 3 hypoxia) was observed at Dose Level 4 (360 mg/m2). The AUC of 17AAG increased with dose, with a linear relationship between end of infusion 17AAG plasma concentration and AUC. The AUC of 17AAG increased with dose, with a linear relationship between end of infusion 17AAG plasma concentration and AUC. Clearance ranged between 12.5 and 29.6 l/hr/m2 (median, 21.6 l/h/m2) and did not change with increasing doses. Post-treatment increases in Hsp70 in PBMCs have been observed in pts treated with 17AAG doses at or above 150 mg/m2. Declines in Akt and IGF1R in PBMCs have been seen in some but not all pts following treatment. Conclusions: 17AAG is well tolerated in children at dose levels studied to date. 17AAG dose escalation continues and at the time of the meeting, updated data will be reported. No significant financial relationships to disclose.

Effect of Early Normotension with Olmesartan on Rho-kinase Activity in Hypertensive Patients

2019 ◽  
Vol 18 (1) ◽  
pp. 87-91 ◽  
Author(s):  
Claudio Cantin ◽  
Jorge E. Jalil ◽  
Juan F. Bulnes ◽  
Ulises Novoa ◽  
Paul MacNab ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Kinase Activity ◽  
Clinical Evidence ◽  
Mononuclear Cells ◽  
Treatment Initiation ◽  
Rho Kinase ◽  
Angiotensin Ii Receptor ◽  
Peripheral Blood Mononuclear ◽  
Hypertensive Patients ◽  
Rock Activity

Background: Angiotensin II is a potent activator of the Rho-kinase (ROCK) pathway, through which it exerts some of its adverse vasoconstrictor effects. Clinical evidence on the effects of blocking the angiotensin II receptor 1 on ROCK activity in hypertensive patients is scarce. Objective: To demonstrate that ROCK activity in peripheral blood mononuclear cells (PMBCs) in patients with essential hypertension is reduced earlier than previously observed, along with blood pressure (BP) lowering on treatment with olmesartan. Methods: Prospective pilot open study; 17 hypertensive patients were treated with progressive olmesartan doses starting with 20 mg qd. BP was measured at 3, 6 and 9 weeks after treatment initiation. If treatment failed to normalize BP after 3 weeks, olmesartan dose was increased to 40 mg qd, and if still hypertensive after 6 weeks, 12.5 mg of hydrochlorothiazide qd was added. ROCK activity was measured at baseline and 9 weeks after treatment as myosin phosphatase target subunit 1 phosphorylation (MYPT1-p/T ratio) in PBMC. Results: Mean baseline BP was 162 ± 4.9/101 ± 2.4 mmHg. After 9 weeks of treatment, both systolic and diastolic BP were reduced by 41 and 22 mmHg, respectively (p<0.05). Mean pretreatment MYPT1- p/T ratio in PMBCs was significantly reduced by 80% after 9 weeks with olmesartan (p<0.01). Conclusion: Normotension achieved after 9 weeks in 82% of the patients treated with olmesartan was associated with a significant reduction of ROCK activity in PBMC.

scholarly journals Blood functional assay for rapid clinical interpretation of germline TP53 variants

2020 ◽  
pp. jmedgenet-2020-107059 ◽  
Author(s):  
Sabine Raad ◽  
Marion Rolain ◽  
Sophie Coutant ◽  
Céline Derambure ◽  
Raphael Lanos ◽  
...  
Keyword(s):  
Mononuclear Cells ◽  
Transcriptional Response ◽  
Functional Assay ◽  
Mrna Levels ◽  
Peripheral Blood Mononuclear ◽  
Patients With Cancer ◽  
Pathogenic Variants ◽  
Functional Variants ◽  
Multiplex Ligation Probe Amplification ◽  
P53 Mrna

BackgroundThe interpretation of germline TP53 variants is critical to ensure appropriate medical management of patients with cancer and follow-up of variant carriers. This interpretation remains complex and is becoming a growing challenge considering the exponential increase in TP53 tests. We developed a functional assay directly performed on patients’ blood.MethodsPeripheral blood mononuclear cells were cultured, activated, exposed to doxorubicin and the p53-mediated transcriptional response was quantified using reverse transcription–multiplex ligation probe amplification and RT-QMPSF assays, including 10 p53 targets selected from transcriptome analysis, and two amplicons to measure p53 mRNA levels. We applied this blood functional assay to 77 patients addressed for TP53 analysis.ResultsIn 51 wild-type TP53 individuals, the mean p53 functionality score was 12.7 (range 7.5–22.8). Among eight individuals harbouring likely pathogenic or pathogenic variants, the scores were reduced (mean 4.8, range 3.1–7.1), and p53 mRNA levels were reduced in patients harbouring truncating variants. We tested 14 rare unclassified variants (p.(Pro72His), p.(Gly105Asp), p.(Arg110His), p.(Phe134Leu), p.(Arg158Cys), p.(Pro191Arg), p.(Pro278Arg), p.(Arg283Cys), p.(Leu348Ser), p.(Asp352Tyr), p.(Gly108_Phe109delinsVal), p.(Asn131del), p.(Leu265del), c.-117G>T) and 12 yielded functionally abnormal scores. Remarkably, the assay revealed that the c.*1175A>C polymorphic variant within TP53 poly-adenylation site can impact p53 function with the same magnitude as a null variant, when present on both alleles, and may act as a modifying factor in pathogenic variant carriers.ConclusionThis blood p53 assay should therefore be a useful tool for the rapid clinical classification of germline TP53 variants and detection of non-coding functional variants.

Phase I Study of the Novel Epothilone Analog Ixabepilone (BMS-247550) in Patients With Advanced Solid Tumors and Lymphomas

2007 ◽  
Vol 25 (9) ◽  
pp. 1082-1088 ◽  
Author(s):  
Carol Aghajanian ◽  
Howard A. Burris ◽  
Suzanne Jones ◽  
David R. Spriggs ◽  
Marvin B. Cohen ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Solid Tumors ◽  
Dose Escalation ◽  
Mononuclear Cells ◽  
Degradation Products ◽  
Standard Dose ◽  
Chemical Degradation ◽  
Maximum Plasma ◽  
Advanced Solid Tumors ◽  
Phase Ii Studies

Purpose To establish the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), safety, pharmacokinetics, and pharmacodynamics of ixabepilone when administered as a 1-hour infusion every 3 weeks to patients with advanced solid tumors or relapsed/refractory non-Hodgkin's lymphoma. Dosing schedules of 40 mg/m2 and 50 mg/m2 over 3 hours were also evaluated. Patients and Methods Sixty-one patients were enrolled using an initial accelerated dose-escalation phase followed by a standard dose-escalation phase, with doses of ixabepilone ranging from 7.4 to 65 mg/m2. The pharmacokinetics of ixabepilone and two of its chemical degradation products were evaluated. Plasma pharmacodynamics were evaluated for both 1- and 3-hour infusions using an assay that measures the amount of endogenous tubulin in peripheral-blood mononuclear cells that exists in the polymerized versus the unpolymerized state. Response evaluation was performed every 6 weeks. Results The most common DLTs were neutropenia, stomatitis/pharyngitis, myalgia, and arthralgia. The MTD of ixabepilone as a 1-hour infusion every 3 weeks was established as 50 mg/m2. The maximum plasma concentration and area under the plasma concentration time curve appeared to increase less than proportionally to dose. Durable objective responses were seen in eight patients, including two complete responses. Five of the responders had experienced treatment failure with a taxane. Conclusion The recommended dose of ixabepilone for the initiation of phase II studies on the basis of these results is 50 mg/m2 over 1 hour every 3 weeks. The promising efficacy and tolerability results demonstrated by ixabepilone in this study warrant its continued development.

Phase 1/2 study of eprenetapopt (APR-246) in combination with pembrolizumab in patients with solid tumor malignancies.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. TPS3161-TPS3161
Author(s):  
Ecaterina Elena Dumbrava ◽  
Amit Mahipal ◽  
Xin Gao ◽  
Geoffrey Shapiro ◽  
Jason S. Starr ◽  
...  
Keyword(s):  
Solid Tumors ◽  
Mononuclear Cells ◽  
Phase 1 ◽  
Objective Response ◽  
Progression Free Survival ◽  
Maximum Tolerated Dose ◽  
Tumor Growth Inhibition ◽  
Advanced Solid Tumors ◽  
Peripheral Blood Mononuclear

TPS3161 Background: The p53 pathway has been implicated in antitumor immunity, including antigen presentation and T-cell proliferation. Loss of p53 function can increase resistance to immunotherapy across many tumor types. Eprenetapopt (eprenet) is a small molecule that stabilizes the folded structure of p53, resulting in activation of mutant p53 and stabilization of wild-type (WT) p53. It also targets the cellular redox homeostasis, resulting in induction of apoptosis in tumor cells. In vivo, mice carrying supernumerary copies of the TP53 gene harbor a pro-inflammatory tumor microenvironment, an effect recapitulated in TP53 normal-copy mice treated with eprenetapopt. Combining eprenetapopt and anti-PD1 or anti-CTLA4 therapy resulted in enhanced tumor growth inhibition and improved survival in TP53 WT mice inoculated with B16 melanoma and MC38 colon adenocarcinoma cells . Based on these results, we hypothesized that eprenet-induced p53 stabilization may augment response to immunotherapy. To test this hypothesis, we are conducting a phase 1b/2 study of eprenet in combination with pembrolizumab (eprenet+pembro) in pts with solid tumors. Methods: The primary objectives are to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) and to assess the safety and tolerability of eprenet+pembro in pts with advanced solid tumors. The secondary objectives are to estimate the anti-tumor activity and to describe the pharmacokinetics of the combination. Exploratory objectives include assessing predictive and pharmacodynamic markers of response. The study includes a safety lead-in with a 3+3 dose de-escalation design for pts with advanced solid tumors with known tumor TP53 mutation status ( TP53 WT is acceptable) (max 18 pts), followed by expansion cohorts in pts with NSCLC, gastric/GEJ and urothelial cancer (max 100 pts). In expansion, pts with urothelial and gastric cancers must be naïve to anti-PD-1/ L1 therapy. Eprenet is given IV once daily on Days 1–4 while pembro is administered on Day 3 of each 21-day cycle. The RP2D of eprenet+pembro is considered the dose at which ≤ 1 of 6 pts in a cohort has a dose-limiting toxicity (DLT). Primary endpoints are occurrence of DLTs, adverse events (AEs) and serious AEs with eprenet+pembro. Key secondary endpoints are best objective response, progression free survival and overall survival. Exploratory endpoints include gene mutations by next generation sequencing (including TP53), mRNA expression, multiplex immunohistochemistry and transcriptomics, multiplex flow cytometry on peripheral blood mononuclear cells and cytokines in serum. Continuous monitoring of toxicity will be conducted. The trial opened in May 2020 and is actively enrolling patients. Clinical trial information: NCT04383938.

scholarly journals An open-label, phase II multicohort study of an oral hypomethylating agent CC-486 and durvalumab in advanced solid tumors

2020 ◽  
Vol 8 (2) ◽  
pp. e000883
Author(s):  
Kirsty Taylor ◽  
Helen Loo Yau ◽  
Ankur Chakravarthy ◽  
Ben Wang ◽  
Shu Yi Shen ◽  
...  
Keyword(s):  
Solid Tumors ◽  
Mononuclear Cells ◽  
Dna Demethylation ◽  
Lessons Learned ◽  
Clinical Activity ◽  
Open Label ◽  
Peripheral Blood Mononuclear ◽  
Global Methylation ◽  
Hypomethylating Agent ◽  
Tumor Biopsies

PurposeTo evaluate whether administration of the oral DNA hypomethylating agent CC-486 enhances the poor response rate of immunologically ‘cold’ solid tumors to immune checkpoint inhibitor durvalumab.Experimental designPD-L1/PD-1 inhibitor naïve patients with advanced microsatellite stable colorectal cancer; platinum resistant ovarian cancer; and estrogen receptor positive, HER2 negative breast cancer were enrolled in this single-institution, investigator-initiated trial. Two 28 day regimens, regimen A (CC-486 300 mg QD Days 1–14 (cycles 1–3 only) in combination with durvalumab 1500 mg intravenous day 15) and regimen B (CC-486 100 mg QD days 1–21 (cycle 1 and beyond), vitamin C 500 mg once a day continuously and durvalumab 1500 mg intravenous day 15) were investigated. Patients underwent paired tumor biopsies and serial peripheral blood mononuclear cells (PBMCs) collection for immune-profiling, transcriptomic and epigenomic analyzes.ResultsA total of 28 patients were enrolled, 19 patients treated on regimen A and 9 on regimen B. The combination of CC-486 and durvalumab was tolerable. Regimen B, with a lower dose of CC-486 extended over a longer treatment course, showed less grade 3/4 adverse effects. Global LINE-1 methylation assessment of serial PBMCs and genome-wide DNA methylation profile in paired tumor biopsies demonstrated minimal changes in global methylation in both regimens. The lack of robust tumor DNA demethylation was accompanied by an absence of the expected ‘viral mimicry’ inflammatory response, and consequently, no clinical responses were observed. The disease control rate was 7.1%. The median progression-free survival was 1.9 months (95% CI 1.5 to 2.3) and median overall survival was 5 months (95% CI 4.5 to 10).ConclusionsThe evaluated treatment schedules of CC-486 in combination with durvalumab did not demonstrate robust pharmacodynamic or clinical activity in selected immunologically cold solid tumors. Lessons learned from this biomarker-rich study should inform continued drug development efforts using these agents.Trial registration numberNCT02811497.

scholarly journals Streptococcus pneumoniae Autolysis Prevents Phagocytosis and Production of Phagocyte-Activating Cytokines

2009 ◽  
Vol 77 (9) ◽  
pp. 3826-3837 ◽  
Author(s):  
Anna Martner ◽  
Susann Skovbjerg ◽  
James C. Paton ◽  
Agnes E. Wold
Keyword(s):  
Streptococcus Pneumoniae ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Interleukin 12 ◽  
Dependent Manner ◽  
Peripheral Blood Mononuclear ◽  
Exact Function ◽  
Ifn Γ ◽  
Dose Dependent

ABSTRACT Streptococcus pneumoniae is a major pathogen in humans. The pathogenicity of this organism is related to its many virulence factors, the most important of which is the thick pneumococcal capsule that minimizes phagocytosis. Another virulence-associated trait is the tendency of this bacterium to undergo autolysis in stationary phase through activation of the cell wall-bound amidase LytA, which breaks down peptidoglycan. The exact function of autolysis in pneumococcal pathogenesis is, however, unclear. Here, we show the selective and specific inefficiency of wild-type S. pneumoniae for inducing production of phagocyte-activating cytokines in human peripheral blood mononuclear cells (PBMC). Indeed, clinical pneumococcal strains induced production of 30-fold less tumor necrosis factor (TNF), 15-fold less gamma interferon (IFN-γ), and only negligible amounts of interleukin-12 (IL-12) compared with other closely related Streptococcus species, whereas the levels of induction of IL-6, IL-8, and IL-10 production were similar. If pneumococcal LytA was inactivated by mutation or by culture in a medium containing excess choline, the pneumococci induced production of significantly more TNF, IFN-γ, and IL-12 in PBMC, whereas the production of IL-6, IL-8, and IL-10 was unaffected. Further, adding autolyzed pneumococci to intact bacteria inhibited production of TNF, IFN-γ, and IL-12 in a dose-dependent manner but did not inhibit production of IL-6, IL-8, and IL-10 in response to the intact bacteria. Fragments from autolyzed bacteria inhibited phagocytosis of intact bacteria and reduced the in vitro elimination of pneumococci from human blood. Our results suggest that fragments generated by autolysis of bacteria with reduced viability interfere with phagocyte-mediated elimination of live pneumococci.

scholarly journals Galectin-9 expression defines exhausted T cells and impaired cytotoxic NK cells in patients with virus-associated solid tumors

2020 ◽  
Vol 8 (2) ◽  
pp. e001849
Author(s):  
Isobel Okoye ◽  
Lai Xu ◽  
Melika Motamedi ◽  
Pallavi Parashar ◽  
John W Walker ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Solid Tumors ◽  
Mononuclear Cells ◽  
Cell Phenotype ◽  
Peripheral Blood Mononuclear ◽  
Effector Functions ◽  
Cell Functions ◽  
Cell Effector

BackgroundWe have previously reported that the upregulation of galectin-9 (Gal-9) on CD4+ and CD8+ T cells in HIV patients was associated with impaired T cell effector functions. Gal-9 is a ligand for T cell immunoglobulin and mucin domain-3, and its expression on T cells in cancer has not been investigated. Therefore, we aimed to investigate the expression level and effects of Gal-9 on T cell functions in patients with virus-associated solid tumors (VASTs).Methods40 patients with VASTs through a non-randomized and biomarker-driven phase II LATENT trial were investigated. Peripheral blood mononuclear cells and tumor biopsies were obtained and subjected to immunophenotyping. In this trial, the effects of oral valproate and avelumab (anti-PD-L1) was investigated in regards to the expression of Gal-9 on T cells.ResultsWe report the upregulation of Gal-9 expression by peripheral and tumor-infiltrating CD4+ and CD8+ T lymphocytes in patients with VASTs. Our results indicate that Gal-9 expression is associated with dysfunctional T cell effector functions in the periphery and tumor microenvironment (TME). Coexpression of Gal-9 with PD-1 or T cell immunoglobulin and ITIM domain (TIGIT) exhibited a synergistic inhibitory effect and enhanced an exhausted T cell phenotype. Besides, responding patients to treatment had lower Gal-9 mRNA expression in the TME. Translocation of Gal-9 from the cytosol to the cell membrane of T cells following stimulation suggests persistent T cell receptor (TCR) stimulation as a potential contributing factor in Gal-9 upregulation in patients with VASTs. Moreover, partial colocalization of Gal-9 with CD3 on T cells likely impacts the initiation of signal transduction via TCR as shown by the upregulation of ZAP70 in Gal-9+ T cells. Also, we found an expansion of Gal-9+ but not TIGIT+ NK cells in patients with VASTs; however, dichotomous to TIGIT+ NK cells, Gal-9+ NK cells exhibited impaired cytotoxic molecules but higher Interferon gamma (IFN-γ) expression.ConclusionOur data indicate that higher Gal-9-expressing CD8+ T cells were associated with poor prognosis following immunotherapy with anti-Programmed death-ligand 1 (PD-L1) (avelumab) in our patients’ cohort. Therefore, for the very first time to our knowledge, we report Gal-9 as a novel marker of T cell exhaustion and the potential target of immunotherapy in patients with VASTs.

A Fully Human Antagonist Anti-CD40 Antibody Triggers Significant Antitumor Activity Against Human Multiple Myeloma.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2414-2414
Author(s):  
Yu-Tzu Tai ◽  
Xian-Feng Li ◽  
Xia Tong2 ◽  
Laurence Catley ◽  
Daniel Santos ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Dependent Manner ◽  
Peripheral Blood Mononuclear ◽  
Specific Lysis ◽  
Growth And Survival ◽  
Human Multiple Myeloma ◽  
Dose Dependent

Abstract We previously demonstrated that CHIR-12.12, a fully human anti-CD40 mAb (IgG1) generated in XenoMouseÒ mice (Abgenix, Inc), blocks CD40/CD40 ligand (CD40L) interactions and has more potent anti-lymphoma activity than Rituximab both in vivo and in vitro (abstract #2386, ASH, San Diego, Dec. 2003). In this study, we assess the efficacy of CHIR-12.12 against human multiple myeloma (MM) using CD40-expressing MM cell lines and purified CD138+ patient cells. CHIR-12.12 binds to purified CD138+ MM cells in &gt;80% (10/12) of patient samples, as measured by flow cytometry: the mean fluorescence intensity (MFI) range was 1 to 20 for CHIR-12.12 vs 0.2–0.9 for control human IgG1. We next examined the antagonist activity of CHIR-12.12 in MM cells. CHIR-12.12 blocked CD40L-mediated proliferation of CD40-expressing MM lines and purified CD138+ patient cells from 2 MM patients in a dose-response manner. In contrast, CHIR-12.12 alone did not alter constitutive MM cell proliferation. Immunoblotting analysis demonstrated that PI3-K/AKT, NF-kB, and ERK activation induced by hCD40L in the 12BM MM cell line was significantly inhibited by CHIR-12.12 (5 μg/ml). Adhesion of MM cells to bone marrow stromal cells (BMSCs) confers growth and survival benefit for tumor cells. Since CD40 activation, either by stimulatory mouse anti-CD40 mAb G28.5 or formaldehyde-fixed CHO cells expressing hCD40L, induces MM cell adhesion to fibronectin (FN) or BMSCs, we next asked whether antagonist CHI12.12 abrogates this process. CHIR-12.12 inhibited CD40L-induced adhesion of MM cell lines to FN in a dose dependent manner (0.001-10 μg/ml), whereas control human IgG did not. Moreover, CHIR-12.12 (1 μg/ml) blocked hCD40L-induced adhesion of freshly isolated patient MM cells to BMSCs. Adhesion of MM cells to BMSCs induces IL-6 secretion, an important growth and survival cytokine for MM cells, and treatment of MM cells with hCD40L further augmented adhesion-induced IL-6 secretion. Conversely, pretreatment of CD40-expressing MM cell lines with CHIR-12.12 significantly decreased IL-6 secretion triggered by coculture of MM cells with BMSCs. We next examined whether CHIR-12.12 stimulates antibody-dependent cellular cytotoxicity (ADCC) against CD40-expressing MM cells. Human peripheral blood mononuclear cells and purified NK cells (CD56+CD3−) were used as effector cells. CHIR-12.12 triggered MM cell lysis in a dose dependent manner, as measured in CD40-expressing MM cell lines. The maximum specific lysis of 20–70 % was achieved at 10 μg/ml concentration of CHIR-12.12. CHIR-12.12 mediated lysis was specific to CD40-expressing MM cells, as CHIR-12.12 did not induce ADCC against CD40-negative MM cells. Importantly, CHIR-12.12 induced ADCC against CD138+ cells isolated from 2 MM patients. These results provide preclinical rationale for clinical evaluation of CHIR-12.12 with the goal of improving patient outcome in MM.

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