Single Dose Of Bortezomib Research Articles

A Phase I Study of the Safety and Feasibility of Bortezomib in Combination With G-CSF for Stem Cell Mobilization in Patients With Multiple Myeloma

BackgroundWe previously reported that administration of bortezomib (BTZ) after 4 days of granulocyte colony-stimulating factor (G-CSF) significantly augments mobilization in mice. We hypothesized that administration of BTZ at peak G-CSF mobilization in patients with multiple myeloma (MM) would be safe, augment mobilization, and have an in vivo purging effect on circulating myeloma cells. Patients and MethodsThis was a phase I study using 3 dose levels of BTZ. G-CSF was administered for 5 days. On the evening of the fourth day, a single dose of BTZ was administered. Peripheral blood was drawn 1 to 2 hours before and 15 to 18 hours after BTZ administration (before day 5 G-CSF administration) to analyze the mobilization effect of BTZ. Standard apheresis was then performed starting on day 5. After mobilization, patients underwent autologous stem cell transplantation (ASCT) per institutional guidelines. ResultsTen patients were enrolled. There were no dose-limiting toxicities. Median peripheral blood CD34+ cells at day 4 before BTZ administration was 16 per microliter and 15 hours later was 32 per microliter suggesting that administration of BTZ at peak G-CSF mobilization augments the mobilization effect of G-CSF. The effect of BTZ on circulating MM cells was unclear. All patients had successful engraftment after ASCT. ConclusionAdministration of 1 dose of BTZ at peak G-CSF mobilization was safe and well tolerated, enhanced stem cell mobilization, and did not affect graft viability. The mobilization effect of BTZ at peak G-CSF mobilization shown in this phase I study needs to be confirmed in a larger randomized trial.

A Phase I Study of the Safety and Feasibility of Bortezomib in Combination with G-CSF for Stem Cell Mobilization in Patients with Multiple Myeloma

Background: Granulocyte colony-stimulating factor (G-CSF) is the most frequently used agent for stem cell mobilization in multiple myeloma (MM). G-CSF results in suboptimal stem cell yields in 5-30% of MM patients and results in the mobilization of both progenitor cells and tumor cells. While the consequence of reinfusing malignant cells remains unclear, one prospective study has suggested that the presence of myeloma cells in PBSC grafts correlates with poor outcome after transplantation. Thus, in vivo or ex vivo purging of myeloma cells in PBSC products may represent a valid strategy for reducing relapse.In this phase I study, we explored the mobilization effect of bortezomib (BTZ) when given at peak G-CSF mobilization. We previously reported that in mice, administration of BTZ after 4 days of G-CSF augments mobilization with G-CSF significantly by modulating VLA-4/VCAM-1 axis (Ghobadi, et al, Blood, 2014). We hypothesize that administration of BTZ will augment mobilization and have an in vivo purging effect on myeloma cells.Objectives: 1) To determine the maximum tolerated dose (MTD) of BTZ when administered with G-CSF for stem cell mobilization; 2) To analyze the mobilization effect of BTZ, 3) To determine the effect of BTZ on frequency and number of circulating myeloma cells.Methods: This was a phase I study using 3 dose levels of BTZ (0.7, 1.0, and 1.3 mg/m2). G-CSF was administered (10 μg/kg) for five days. On the evening of the fourth day, a single dose of BTZ was administered. Peripheral blood was drawn 1-2 hours before and 15-18 hours following BTZ administration (prior to day 5 G-CSF administration) to analyze the effect of BTZ on peak CD34+ count and circulating myeloma cells. Standard apheresis was then performed (~20L). If the target collection was not met after 1 apheresis, up to 3 additional days of G-CSF and apheresis were performed. No additional BTZ was administered. Following mobilization patients underwent ASCT per institutional guidelines. Eligible patients had upfront MM and were candidates for ASCT. Prior BTZ exposure was not exclusionary. Dose limiting toxicity was defined as grade 4 hematologic toxicities and any grade 3-5 non hematologic toxicities within 28 days of BTZ administration.Results: Ten patients were enrolled; 1 patient at 0.7mg/m2, 3 at 1.0mg/m2, and 6 at 1.3mg/m2. The median age was 64 years; 60% were male. All patients had received prior BTZ, largely in combination regimens with lenalidomide or cyclophosphamide, the median number of prior cycles was 4.There were no dose limiting toxicities or serious adverse events reported, therefore an MTD was not established.Prior to G-CSF administration, the mean PB CD34+ was 1/μL (range: 0-3/ μL). Mean PB CD34+ cells at Day 4 prior to BTZ administration and 15 hours after BTZ administration (Day 5 prior to G-CSF administration and apheresis) were 25/μL (range: 1-59/ μL) and 38/μL (range: 2-84/ μL) respectively suggesting that administration of BTZ at peak G-CSF mobilization can potentially increase circulating CD34+ cells (Figure 1). The median CD34+ collection following 1 apheresis was 4.5 x 106/kg. Fifty percent of the patients collected > 5.0 x 106/kg CD341+ cells after 1 apheresis, 70% in 1-4 apheresis. Correlative studies using clonoSEQ technology are currently being performed to analyze the effect of BTZ on circulating myeloma cells.At the time of abstract preparation, 8 patients have subsequently undergone ASCT. The median times to neutrophil and platelet engraftment were 11.5 and 22.5 days, respectively. The complete response rate (CRR) was 29%. To date, there has been one case or relapse/progression at a median follow-up of 5.6 months.Discussion: Administration of BTZ at peak G-CSF mobilization was safe and well tolerated and enhanced G-CSF-induced stem cell mobilization. BTZ administration did not seem to impact graft viability as all patients had successful engraftment and the time to engraftment was unaffected. Correlative studies are currently being performed to determine if BTZ had an in vivo purging effect on myeloma cells as we hypothesized. [Display omitted] DisclosuresUy:Glycomimetics: Consultancy; Boehringer Ingelheim: Consultancy. Vij:Novartis: Consultancy; Bristol-Myers Squibb: Consultancy; Karyopharma: Consultancy; Janssen: Consultancy; Takeda: Consultancy, Research Funding; Jazz: Consultancy; Shire: Consultancy; Celgene: Consultancy; Amgen: Consultancy, Research Funding. DiPersio:Incyte Corporation: Research Funding.

Updated Outcomes of Fludarabine/Melphalan/Bortezomib (Flu/Mel/Vel) Conditioning for Upfront Allogeneic Hematopoietic Cell Transplantation in Multiple Myeloma

Background:Multiple myeloma remains incurable despite impressive array of available novel agents and therapeutic strategies. Allogeneic hematopoietic cell transplantation (HCT) remains the only potentially curative option for patients with multiple myeloma but it is limited by its toxicities. We previously reported initial result of a phase 2 study of upfront allogeneic HCT in myeloma patients achieving at least very good partial response (VGPR) after initial therapy (Nishihori, et al. ASH 2013 abstract 3390) and here we report more mature results after a median follow up of 3 years.Methods:Twenty seven myeloma patients received allogeneic HCT between 01/2010 and 02/2015 at Moffitt Cancer Center (NCT 00948922). Eligible patients were age ≤ 60, achieving first ≥ VGPR or complete response (CR), and have 8/8 HLA-matched related or unrelated donors. Conditioning regimen consisted of fludarabine 30 mg/m2 for 4 days (days -6, -5, -4, and -3) and melphalan 70 mg/m2 for 2 days (days -4 and -3) followed by a single dose of bortezomib 1.3 mg/m2 on day -3 (Flu/Mel/Vel regimen). GVHD prophylaxis was initially left to the discretion of physicians but later modified to only tacrolimus/methotrexate. No maintenance therapy was prescribed after allogeneic HCT.Results:The median age at transplant was 50 (range, 25-58) years. Disease status at the time of allogeneic HCT was VGPR (n=17: 63%) and CR/stringent CR (n=10: 37%). All patients received unmanipulated peripheral blood stem cell grafts from HLA-matched related donors (n=14) or HLA-matched unrelated donors (n=13). Graft-versus-host disease (GVHD) prophylaxis was tacrolimus plus either methotrexate (n=19: 70%), or mycophenolate mofetil (n=4), or sirolimus (n=4). All patients achieved neutrophil engraftment with a median of 15 (range, 11-19) days. Platelet engraftment was achieved with a median of 17 (range, 13 - 35) days and 2 patients did not recover platelets. The cumulative incidences of grades II-IV and grades III-IV acute GVHD at day 100 were 63.6% (95% confidence interval (CI): 43.1-81.1) and 19.6% (95%CI: 5.4-39.9), respectively. The cumulative incidence of moderate to severe chronic GVHD was 56.4% (95%CI: 36.3-75.5) at 1-year. The cumulative incidences of transplant-related mortality at day 100, 1 year and 2 years were 7.4% (95%CI: 0.8-20.0), 11.1% (95%CI: 2.7-25.4), and 11.1% (95%CI: 2.7-25.4), respectively. Progression-free survival estimates at 1, 2, and 3 years were 74.1% (95%CI: 53.2-86.7), 65.1% (95%CI: 43.3-80.2), and 65.1% (95%CI: 49.9-87.5), respectively. With a median follow up of 39 months for surviving patients, overall survival estimates at 1, 2 and 3 years were 85% (95%CI: 64.9-94.1), 75.4% (95%CI: 52.6-88.3), and 69.1% (95%CI: 53.8-93.5), respectively.Conclusions:The results of the this phase 2 trial of upfront allogeneic HCT with fludarabine/melphalan/bortezomib (Flu/Mel/Vel) conditioning are promising and provide the rationale for reasonable potentially curative option to younger and fit patients who are eligible for upfront intensive consolidation strategy. This approach may be potentially valuable for those with high-risk myeloma and a multicenter study is currently being conducted (BMT CTN protocol 1302:NCT02440464). DisclosuresNishihori:Novartis: Research Funding; Signal Genetics: Research Funding. Baz:Takeda/Millennium: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Novartis: Research Funding; Karyopharm: Research Funding; Bristol-Myers Squibb: Research Funding; Signal Genetics: Research Funding. Shain:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen/Onyx: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Signal Genetics: Research Funding; Takeda/Millennium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Speakers Bureau. Alsina:Signal Genetics: Consultancy; Novartis: Research Funding; Takeda/Millennium: Research Funding; Amgen/Onyx: Consultancy, Speakers Bureau.

Safety and Efficacy of Targeted-Dose Busulfan and Bortezomib as a Conditioning Regimen for Patients with Relapsed Multiple Myeloma Undergoing a Second Autologous Blood Progenitor Cell Transplantation

Patients with multiple myeloma (MM) who relapse after autologous transplantation have limited therapeutic options. We conducted a prospective, multicenter, phase IIa study to investigate the safety and efficacy of i.v. busulfan (Bu) in combination with bortezomib as a conditioning regimen for a second autotransplantation. Because a safe Bu exposure was unknown in patients receiving this combination, Bu was initially targeted to a total area under the concentration–time curve (AUC) of 20,000 μM × minute. As no concentration-limiting toxicity was observed in 6 patients, this Bu exposure was utilized in the following treatment cohort (n = 24). Individualized Bu dose, based on test dose .8 mg/kg pharmacokinetics (PK), was administered daily for 4 consecutive days starting 5 days before transplantation, followed by a single dose of bortezomib (1.3 mg/m2) 1 day before transplantation. The total mean dose of i.v. Bu (including the test dose and 4-day administration) was 14.2 mg/kg (standard deviation = 2.48; range, 8.7 to 19.2). Confirmatory PK demonstrated that only 2 of 30 patients who underwent transplantation were dosed outside the Bu AUC target and dose adjustments were made for the last 2 doses of i.v. Bu. The median age was 59 years (range, 48 to 73). Median time from first to second transplantation was 28.0 months (range, 12 to 119). Of 26 evaluable patients, 10 patients attained a partial response (PR) or better at 3 months after transplantation, with 2 patients attaining a complete response. At 6 months after transplantation, 5 of 12 evaluable patients had maintained or improved their disease status. Median progression-free survival was 191 days, whereas median overall survival was not reached during the study period. The most common grade 3 and 4 toxicities were febrile neutropenia (50.0%) and stomatitis (43.3%). One transplantation-related death was observed. A combination of dose-targeted i.v. Bu and bortezomib induced PR or better in one third of patients with MM who underwent a second autotransplantation, with acceptable toxicity.

Allogeneic Hematopoietic Cell Transplantation Using Fludarabine, Melphalan and Bortezomib (Flu/Mel/Vel) Conditioning For Consolidation Of VGPR Or CR In Myeloma

BackgroundThe use of allogeneic hematopoietic cell transplantation (HCT) in multiple myeloma (MM) remains controversial but the role of allogeneic HCT for consolidation of initial response in the era of novel agents has not been defined. Therefore, we conducted a phase 2 study of allogeneic HCT in MM patients achieving at least very good partial response (VGPR) after initial therapy. MethodsSeventeen MM patients with first VGPR or complete remission (CR) received allogeneic HCT between 01/2010 and 04/2013 at Moffitt Cancer Center (NCT 00948922). Eligible patients were age ≤ 60, achieving ≥ VGPR, and have suitable HLA-matched donors. Six patients received bortezomib plus lenalidomide induction, 7 received bortezomib-based, and 4 received lenalidomide-based induction. Three patients (18%) underwent autologous HCT with melphalan plus bortezomib conditioning (melphalan 100 mg/m2 for 2 days followed by bortezomib 1.3 mg/m2) following induction therapies in order to achieve further cytoreduction. Conditioning regimen before allogeneic HCT consisted of fludarabine 30 mg/m2 for 4 days and melphalan 70 mg/m2 for 2 days followed by a single dose of bortezomib 1.3 mg/m2 (Flu/Mel/Vel). GVHD prophylaxis was tacrolimus plus either methotrexate (n=9), or mycophenolate mofetil (n=4), or sirolimus (n=4). No maintenance therapy was prescribed after allogeneic HCT. ResultsThe median age at transplant was 51 (25 – 57) years and the median time from initial therapy to transplant was 236 (126 – 418) days. Seven patients (41%) have high-risk cytogenetics/FISH. The median number of prior therapy was 1. Disease status at the time of allogeneic HCT was VGPR (n=8), CR (n=3), or stringent CR (n=6). All patients received unmanipulated peripheral blood stem cell grafts from HLA-matched sibling donors (n=7) or 8/8 HLA-matched unrelated donors (n=10). All patients achieved neutrophil engraftment with a median of 14 (11 - 18) days and platelet engraftment with a median of 17 (13 - 21) days. All patients established stable donor cell chimerism. Best responses after allogeneic HCT were CR (n=2), sCR (n=13), and disease progression (n=2). The 2-year progression-free survival estimate is 80% (95%CI: 51 – 98) for standard-risk group and 51% (95%CI: 15 – 87) for high-risk, respectively. With a median follow up of 18 (3 - 43) months for surviving patients, the 2-year overall survival estimate is 88% (95%CI: 68 – 99). The cumulative incidence of non-relapse mortality was 6% (95%CI: 0.0 – 22) at 100 days and 13% (95%CI: 1 – 34) at 1 year, respectively. The cumulative incidence of grades 2-4 acute GVHD at day 100 was 41% (95% CI: 20 – 65) and the cumulative incidence of moderate to severe chronic GVHD at 1 year was 8.0% (95% CI: 0.0 – 29). ConclusionsThese results indicate that allogeneic HCT for MM in VGPR or CR as consolidation achieves favorable disease control. The study is ongoing to assess long-term safety of this modality. A multicenter trial is planned to evaluate the utility of allogeneic HCT in high-risk MM.Overall Survival▪Months Disclosures:Off Label Use: bortezomib - transplant conditioning. Alsina:Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding.

The Protection and Therapy Effects of Bortezomib in Murine Acute Graft-Versus-Host Disease

Acute graft-versus-host disease (aGVHD) remains a life-threatening complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The proteasome inhibitor bortezomib exhibits potent antitumor activity with anti-inflammatory and immunomodulatory effects. However, the effects of bortezomib on aGVHD are unclear. In this study, we assessed the effects of bortezomib on aGVHD in the C57BL/6 (H-2b+) donor to BALB/c (H-2d+) recipient major histocompatibility complex-mismatched model. Two bortezomib doses (1 mg/kg each) on days 0 and +1 after transplantation, significantly increased survival rate and attenuated clinical signs of aGVHD without altering donor reconstitution. However, GVHD-associated mortality was significantly increased when bortezomib administration was delayed to day +2 posttransplantation. Furthermore, a single dose of bortezomib on day 0 or day +1 after transplantation also decreased the GVHD protective effect. Consistent with the above data, serum cytokine levels of IL-2, IFN-γ and TNF-α were significantly decreased at day +7 posttransplantation after two doses of bortezomib compared with aGVHD control group. Moreover, two administrations of bortezomib reduced donor T–cell expansion at days +3 and +4 posttransplantation and enhanced donor CD4+T-cell differentiation into the T help cell 17 subset at day +7 after transplantation in spleens. These results indicated that the protective effects of bortezomib on aGVHD were dependent on the time and the frequency of bortezomib administration.

Allogeneic Hematopoietic Cell Transplantation for Consolidation of Vgpr or Cr in Myeloma

Abstract 4581 Allogeneic hematopoietic cell transplantation (HCT) from HLA-identical siblings has been shown to prolong survival of patients with multiple myeloma in some studies. However, all published clinical trials of up front allogenic transplant for myeloma were conducted before thalidomide, lenalidomide and bortezomib became available; as such, less than 10% of the patients were in complete remission (CR) at time of transplantation. With contemporary therapy incorporating novel agents, more than 50% of patients achieve very good partial response (VGPR) or better (VGPR or CR). We summarize our experience with the safety and efficacy of allogeneic transplantation for patients achieving VGPR or better following induction therapy containing novel agent(s). Thirteen myeloma patients with first VGPR or CR received allogeneic HCT between July 2007 and January 2011. Median age at transplant was 45 years (range, 25 – 59), median time from initial therapy to transplant was 236 days (range, 122 – 410). Six patients (46%) have high-risk cytogenetics/FISH. Five patients received bortezomib plus lenalidomide induction therapy and eight patients received bortezomib-induction. Three patients (23%) underwent autologous HCT with melphalan plus bortezomib conditioning (melphalan 100 mg/m 2 for 2 days followed by bortezomib 1.3 mg/m 2 ) subsequent to induction therapies to achieve further cytoreduction prior to allogeneic HCT. Median number of prior therapies was 2 (range, 1–2). Disease status at the time of allogeneic HCT was stringent CR (n=5), CR (n=3), and VGPR (n=5). All patients received unmanipulated peripheral blood stem cell grafts from HLA-matched sibling donors (n=5) and HLA-matched unrelated donors (n=8). Six patients received fludarabine 30 mg/m 2 for 4 days and melphalan 70 mg/m 2 for 2 days followed by a single dose of bortezomib 1.3 mg/m 2 (Flu/Mel/Vel). Seven patients received fludarabine 40 mg/m 2 for 4 days and melphalan 70 mg/m 2 for 2 days (Flu/Mel). Graft-versus-host disease (GVHD) prophylaxis constitutes tacrolimus/methotrexate (n=5), tacrolimus/mycophenolate mofetil (n=4), and tacrolimus/sirolimus (n=4). All patients achieved neutrophil engraftment after a median of 17 days (range, 11 – 19), and all patients achieved platelet engraftment after a median of 17 days (range, 12 – 21). All patients established stable donor cell chimerism. Best responses after allogeneic HCT were sCR (n=10), CR (n=2) and VGPR (n=1). The cumulative incidence of grades 2–4 acute GVHD at day 100 was 57% (95% CI 0.30 – 1.00) with Flu/Mel conditioning and 33% (95% CI 0.11 – 1.00) for Flu/Mel/Vel conditioning, respectively (p=0.24). This observation suggests that a single dose of bortezomib 48 hours before HCT may prevent GVHD. One patient died of GVHD complications, 1 had disease progression and 11 remain alive, progression free with a median follow-up of one year (range 4 months to 4 years). The one year progression-free survival estimate is 90% (95%CI 0.71 – 1.00). These initial data indicate that allogenic transplant for myeloma in VGPR or CR is well tolerated. Longer follow-up is required to assess the efficacy of allogeneic HCT in the era of novel agents in preventing progression of the disease. Disclosures: Baz: Millenium: Research Funding, Speakers Bureau; Celgene: Research Funding. Alsina: Millennium: Consultancy, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Allergan: Research Funding.

Treatment with the NF-κB inhibitor bortezomib leads to suppression of proregenerative cytokines and significant mortality after liver resection

Introduction: After liver resections or transplantations ischemia/reperfusion injury or inflammatory processes that are mediated through activation of the transcription factor NF-κB lead to additional tissue damage. Thus, suppression of NF-κB activation could be beneficial for patient outcome after these procedures. Methods: To study this question, primary Kupffer cells were isolated from 7 week-old mice and primary hepatocytes were isolated from human liver explants. Cells were cultivated for two days, treated with the NF-KB inhibitor bortezomib and stimulated with TLR-3 and TLR-4 agonist. Expression of cytokines and genes relevant for inflammation and regeneration (IL-6, IL-10, IFN-β, TGF-β) was assessed by qrt PCR. For survival experiments 8 week old male Wistar rats received liver resections ranging from 30% to 90% partial hepatectomy. 6 animals per group were treated with a single dose of bortezomib (approx. 0,5g/KG body weight) in 150µl NaCl 2h preoperatively. 6 animals received no treatment apart from surgery. Results: In human hepatocytes and mouse KC, bortezomib pretreatment led to potent suppression of TLR3 and -4 induced production of IL-6 and IL-10. On the contrary, bortezomib led to significantly enhanced TLR4-induced IFN-β expression in Kupffer cells. Rats undergoing surgery alone survived until 7d postoperatively, with one exception in the 90% resection group. After bortezomib pretreatment, however, the mortality was 20% after 30% resection, 33% in the 70% resection group and 83% after 90% liver resection. Bortezomib treatment without hepatectomy showed no adverse effects. Conclusion: Bortezomib can strongly reduce the expression of proregenerative cytokines such as IL-6 and upregulate the expression of antiregenerative cytokines such as IFN-β which is associated with significantly enhanced mortality of liver resection. Therefore, this drug is not suitable to treat NF-κB mediated processes such as ischemia/reperfusion injury after liver surgery.

A Novel Mechanism of Action of Bortezomib: Proteasome Inhibition Down-Regulates HLA-Class I on Myeloma and Enhances NK Cell-Mediated Lysis.

Introduction: Natural killer (NK) cell activity is regulated by a dynamic balance between inhibitory and activating receptors that recognize ligands on target cells. Human leukocyte antigen (HLA)-class I, particularly HLA-C and -Bw4 molecules, are key ligands transmitting inhibitory signals to NK cells. NK cells avidly lyse tumor cells that do not display such inhibitory KIR-ligands. The proteasome is responsible for the generation of peptides that bind to and stabilize class I molecules at the cell surface. We hypothesized that bortezomib, a partial proteasome inhibitor that is clinically approved for the treatment of refractory/relapsed myeloma (MM), could reduce HLA expression on MM cells and thus enhance NK cell-mediated cytotoxicity.Methods: HLA-class I or HLA-C expression was assessed using flow cytometry, after gating on AnnexinV/PI double negative cells, and/or confocal microscopy. Expression of other proteins was measured by flow cytometry using specific mAb. NK cell-mediated lysis of myeloma cells was measured by 51Cr-release.Results: Bortezomib at clinically attainable concentrations down-regulated HLA-class I expression on MM cells in a time- and dose-dependent fashion. Reduction of class I post-10 nM bortezomib treatment was observed in all myeloma cell lines tested (n=10), by a median of 49% (range: 19–66%). A similar decrease of HLA-class I was obtained in 10–50 nM bortezomib treated primary MM cells (n=6). Bortezomib significantly enhanced the sensitivity of MM cells to allogeneic and autologous NK cell-mediated lysis. Further, the level of reduction in HLA-class I expression correlated well with increased susceptibility to lysis by NK cells. The level of down-regulation of HLA-class I induced by bortezomib was reproduced by incubating MM cells with HLA-blocking antibody and resulted in equipotent enhancement of NK cell-mediated lysis (Figure 1). The extent of HLA-class I down-regulation by bortezomib was therefore biologically relevant. Down-regulation of HLA-class I was also observed in vivo on purified MM cells 48 hours after a single dose of bortezomib, by a median of 47% (range: 16–63%, n=6, P= .002). HLA-C expression (the principal NK cell inhibitory ligand) was rescued by exogenous provision of HLA-C binding peptides providing a mechanistic explanation for the effect of bortezomib on HLA-class I expression. Finally, we did not observe bortezomib-mediated enhancement of NK cell-mediated lysis of myeloma through receptors other than the KIR receptor family, including tumor necrosis factor related apoptosis-inducing ligand, NKG2D and natural cytotoxicity receptors. HLA-class I down-regulation was not observed in renal cell and breast carcinoma cell lines, which is in keeping with the remarkable activity of bortezomib in myeloma. Our findings have clear therapeutic implications for MM and other NK cell-sensitive malignancies in the context of both allogeneic and autologous adoptively transferred NK cells. [Display omitted]

Proteasome inhibition attenuates hepatic injury in the bile duct-ligated mouse

Proteasome inhibition has recently been demonstrated to inhibit hepatic fibrogenesis in the bile duct-ligated (BDL) mouse by blocking stellate cell NF-kappaB activation. The effect of proteasome inhibition on liver injury, however, is unclear. Our aims were to assess the effect of the proteasome inhibitor bortezomib on liver injury in the BDL mouse. Liver injury was assessed in 7-day BDL mice treated with a single dose of bortezomib on day 4 after bile duct ligation. Despite NF-kappaB inhibition by bortezomib, liver injury and hepatocyte apoptosis were reduced in treated BDL mice. The antiapoptotic effect of bortezomib was likely mediated by an increase in hepatic cellular FLICE inhibitory protein (c-FLIP) levels, a potent antiapoptotic protein. Unexpectedly, numerous mitotic hepatocytes were observed in the bortezomib-treated BDL mice liver specimens. Consistent with this observation, PCNA immunoreactivity and cyclin A protein expression were also increased with bortezomib treatment. Bortezomib therapy was also associated with a decrease in numbers and activation of Kupffer cells/macrophages. In conclusion, these data suggest that the proteasome inhibitor bortezomib reduces hepatocyte injury in the BDL mouse by mechanisms associated with a reduction in hepatocyte apoptosis, a decrease in Kupffer cell/macrophage number and activation, and increased hepatocyte proliferation.