Fasting-mimicking diet and hormone therapy induce breast cancer regression.

Approximately 75% of all breast cancers express the oestrogen and/or progesterone receptors. Endocrine therapy is usually effective in these hormone-receptor-positive tumours, but primary and acquired resistance limits its long-term benefit1,2. Here we show that in mouse models of hormone-receptor-positive breast cancer, periodic fasting or a fasting-mimicking diet3-5 enhances the activity of the endocrine therapeutics tamoxifen and fulvestrant by lowering circulating IGF1, insulin and leptin and by inhibiting AKT-mTOR signalling via upregulation of EGR1 and PTEN. When fulvestrant is combined with palbociclib (a cyclin-dependent kinase 4/6 inhibitor), adding periodic cycles of a fasting-mimicking diet promotes long-lasting tumour regression and reverts acquired resistance to drug treatment. Moreover, both fasting and a fasting-mimicking diet prevent tamoxifen-induced endometrial hyperplasia. In patients with hormone-receptor-positive breast cancer receiving oestrogen therapy, cycles of a fasting-mimicking diet cause metabolic changes analogous to those observed in mice, including reduced levels of insulin, leptin and IGF1, with the last two remaining low for extended periods. In mice, these long-lasting effects are associated with long-term anti-cancer activity. These results support further clinical studies of a fasting-mimicking diet as an adjuvant to oestrogen therapy in hormone-receptor-positive breast cancer.

Targeting the immune microenvironment in Waldenström macroglobulinemia via halting the CD40/CD40-ligand axis.

Recent investigations have improved our understanding of the molecular aberrations supporting Waldenström macroglobulinemia (WM) biology; however, whether the immune microenvironment contributes to WM pathogenesis remains unanswered. First, we showed how a transgenic murine model of human-like lymphoplasmacytic lymphoma/WM exhibits an increased number of regulatory T cells (Tregs) relative to control mice. These findings were translated into the WM clinical setting, in which the transcriptomic profiling of Tregs derived from patients with WM unveiled a peculiar WM-devoted messenger RNA signature, with significant enrichment for genes related to nuclear factor κB-mediated tumor necrosis factor α signaling, MAPK, and PI3K/AKT, which was paralleled by a different Treg functional phenotype. We demonstrated significantly higher Treg induction, expansion, and proliferation triggered by WM cells, compared with their normal cellular counterpart; with a more profound effect within the context of CXCR4C1013G-mutated WM cells. By investigating the B-cell-to-T-cell cross talk at single-cell level, we identified the CD40/CD40-ligand as a potentially relevant axis that supports WM cell-Tregs interaction. Our findings demonstrate the existence of a Treg-mediated immunosuppressive phenotype in WM, which can be therapeutically reversed by blocking the CD40L/CD40 axis to inhibit WM cell growth.

Carfilzomib induction, consolidation, and maintenance with or without autologous stem-cell transplantation in patients with newly diagnosed multiple myeloma: pre-planned cytogenetic subgroup analysis of the randomised, phase 2 FORTE trial.

BACKGROUND: Patients with newly diagnosed multiple myeloma and high-risk cytogenetic abnormalities (HRCA) represent an unmet medical need. In the FORTE trial, lenalidomide and dexamethasone plus carfilzomib (KRd) induction resulted in a higher proportion of patients with at least a very good partial response as compared with carfilzomib, cyclophosphamide, and dexamethasone (KCd), and carfilzomib plus lenalidomide maintenance prolonged progression-free survival compared with lenalidomide maintenance. In this prespecified analysis of the FORTE trial, we described the outcomes of enrolled patients according to their cytogenetic risk. METHODS: The UNITO-MM-01/FORTE was a randomised, open-label, phase 2 trial done at 42 Italian academic and community practice centres, which enrolled transplant-eligible patients with newly diagnosed multiple myeloma aged 18-65 years. Eligible patients had newly diagnosed multiple myeloma based on standard International Myeloma Working Group criteria, a Karnofsky performance status of at least 60%, and had not received any previous treatment with anti-myeloma therapy. At enrolment, patients were stratified according to International Staging System stage (I vs II/III) and age (<60 years vs 60-65 years) and randomly assigned (1:1:1) to KRd plus autologous stem-cell transplantation (ASCT; four 28-day induction cycles with KRd, melphalan at 200 mg/m2 and ASCT [MEL200-ASCT], followed by four 28-day KRd consolidation cycles), 12 28-day KRd cycles, or KCd plus ASCT (four 28-day induction cycles with KCd, MEL200-ASCT, and four 28-day KCd consolidation cycles), using a web-based system (block randomisation, block size of 12). Carfilzomib was administered at 20 mg/m2 on days 1 and 2 of cycle 1, followed by 36 mg/m2 intravenously administered on days 8, 9, 15, and 16 of cycle 1, and then 36 mg/m2 intravenously administered for all subsequent doses on days 1, 2, 8, 9, 15, 16; lenalidomide 25 mg was administered orally on days 1-21; cyclophosphamide 300 mg/m2 was administered orally on days 1, 8, and 15; and dexamethasone 20 mg was administered orally or intravenously on days 1, 2, 8, 9, 15, 16, 22, and 23. After the consolidation phase, patients were stratified according to induction-consolidation treatment and randomly assigned (1:1; block size of 8) to maintenance treatment with carfilzomib plus lenalidomide or lenalidomide alone. Carfilzomib 36 mg/m2 was administered intravenously on days 1-2 and days 15-16, every 28 days for up to 2 years, and lenalidomide 10 mg was administered orally on days 1-21 every 28 days until progression or intolerance in both groups. The primary endpoints were the proportion of patients with at least a very good partial response after induction with KRd versus KCd and progression-free survival with carfilzomib plus lenalidomide versus lenalidomide alone as maintenance treatment. In this preplanned analysis, we included patients enrolled in the FORTE trial with complete cytogenetic data on del(17p), t(4;14), t(14;16), del(1p), gain(1q) (3 copies), and amp(1q) (≥4 copies) assessed by fluorescence in-situ hybridisation analysis on CD138-positive sorted cells. We assessed progression-free survival, overall survival, minimal residual disease negativity, and 1-year sustained minimal residual disease negativity according to the presence of zero, one, and two or more HRCA across treatment groups. The FORTE trial is ongoing, and registered with ClinicalTrials.gov, NCT02203643. FINDINGS: Between Feb 23, 2015, and April 5, 2017, 477 patients were enrolled, of whom 396 (83%) had complete cytogenetic data and were analysed (176 [44%] of whom were women and 220 [56%] were men). The median follow-up from first randomisation was 51 months (IQR 46-56). 4-year progression-free survival was 71% (95% CI 64-78) in patients with zero HRCA, 60% (95% CI 52-69) in patients with one HRCA, and 39% (95% CI 30-50) in patients with two or more HRCA. Compared with patients with zero HRCA, the risk of progression or death was similar in patients with one HRCA (hazard ratio [HR] 1·33 [95% CI 0·90-1·97]; p=0·15) and higher in patients with two or more HRCA (HR 2·56 [95% CI 1·74-3·75]); p<0·0001) across the induction-intensification-consolidation groups. Moreover, the risk of progression or death was also higher in patients with two or more HRCA versus those with one HRCA (HR 1·92 [95% CI 1·34-2·76]; p=0·0004). 4-year overall survival from the first randomisation was 94% (95% CI 91-98) in patients with zero HRCA, 83% (95% CI 76-90) in patients with one HRCA, and 63% (95% CI 54-74) in patients with two or more HRCA. Compared with patients with zero HRCA, the risk of death was significantly higher in patients with one HRCA (HR 2·55 [95% CI 1·22-5·36]; p=0·013) and two or more HRCA (HR 6·53 [95% CI 3·24-13·18]; p<0·0001). Patients with two or more HRCA also had a significantly higher risk of death than those with one HRCA (HR 2·56 [95% CI 1·53-4·28]; p=0·0004). The rates of 1-year sustained minimal residual disease negativity were similar in patients with zero HRCA (53 [35%] of 153] and with one HRCA (57 [41%] of 138) and were lower in patients with two or more HRCA (25 [24%] of 105). The median duration of follow-up from second randomisation was 37 months (IQR 33-42). 3-year progression-free survival from the second randomisation was 80% (95% CI 74-88) in patients with zero HRCA, 68% (95% CI 59-78) in patients with one HRCA, and 53% (95% CI 42-67) in patients with two or more HRCA. The risk of progression or death was higher in patients with one HRCA (HR 1·68 [95% CI 1·01-2·80]; p=0·048) and two or more HRCA (2·74 [95% CI 1·60-4·69], p=0·0003) than in patients with zero HRCA. INTERPRETATION: This preplanned analysis of the FORTE trial showed that carfilzomib-based induction-intensification-consolidation regimens are effective strategies in patients with standard risk (zero HRCA) and high-risk (one HRCA) myeloma, resulting in similar rates of progression-free survival and 1-year sustained minimal residual disease negativity. Despite promising progression-free survival, patients with ultra-high-risk disease (those with 2 or more HRCA) still have an increased risk of progression and death and therefore represent an unmet medical need. FUNDING: Amgen and Celgene/Bristol Myers Squibb.

Sirtuin 6 Regulates the Activation of the ATP/Purinergic Axis in Endothelial Cells.

Sirtuin 6 (SIRT6) is a member of the mammalian NAD+-dependent deac(et)ylase sirtuin family. SIRT6's anti-inflammatory roles are emerging increasingly often in different diseases and cell types, including endothelial cells. In this study, the role of SIRT6 in pro-inflammatory conditions was investigated by engineering human umbilical vein endothelial cells to overexpress SIRT6 (SIRT6+ HUVECs). Our results showed that SIRT6 overexpression affected the levels of adhesion molecules and sustained megakaryocyte proliferation and proplatelet formation. Interestingly, the pro-inflammatory activation of the ATP/purinergic axis was reduced in SIRT6+ HUVECs. Specifically, the TNFα-induced release of ATP in the extracellular space and the increase in pannexin-1 hemichannel expression, which mediates ATP efflux, were hampered in SIRT6+ cells. Instead, NAD+ release and Connexin43 expression were not modified by SIRT6 levels. Moreover, the Ca2+ influx in response to ATP and the expression of the purinergic receptor P2X7 were decreased in SIRT6+ HUVECs. Contrary to extracellular ATP, extracellular NAD+ did not evoke pro-inflammatory responses in HUVECs. Instead, NAD+ administration reduced endothelial cell proliferation and motility and counteracted the TNFα-induced angiogenesis. Altogether, our data reinforce the view of SIRT6 activation as an anti-inflammatory approach in vascular endothelium.

Anticancer Activities of Novel Nicotinamide Phosphoribosyltransferase Inhibitors in Hematological Malignancies.

Targeting cancer cells that are highly dependent on the nicotinamide adenine dinucleotide (NAD+) metabolite is a promising therapeutic strategy. Nicotinamide phosphoribosyltransferase (NAMPT) is the rate-limiting enzyme catalyzing NAD+ production. Despite the high efficacy of several developed NAMPT inhibitors (i.e., FK866 (APO866)) in preclinical studies, their clinical activity was proven to be limited. Here, we report the synthesis of new NAMPT Inhibitors, JJ08, FEI191 and FEI199, which exhibit a broad anticancer activity in vitro. Results show that these compounds are potent NAMPT inhibitors that deplete NAD+ and NADP(H) after 24 h of drug treatment, followed by an increase in reactive oxygen species (ROS) accumulation. The latter event leads to ATP loss and mitochondrial depolarization with induction of apoptosis and necrosis. Supplementation with exogenous NAD+ precursors or catalase (ROS scavenger) abrogates the cell death induced by the new compounds. Finally, in vivo administration of the new NAMPT inhibitors in a mouse xenograft model of human Burkitt lymphoma delays tumor growth and significantly prolongs mouse survival. The most promising results are collected with JJ08, which completely eradicates tumor growth. Collectively, our findings demonstrate the efficient anticancer activity of the new NAMPT inhibitor JJ08 and highlight a strong interest for further evaluation of this compound in hematological malignancies.

Apoptosis reprogramming triggered by splicing inhibitors sensitizes multiple myeloma cells to Venetoclax treatment.

Identification of novel vulnerabilities in the context of therapeutic resistance is emerging as a key challenge for cancer treatment. Recent studies have detected pervasive aberrant splicing in cancer cells, supporting its targeting for novel therapeutic strategies. Here, we evaluated the expression of several spliceosome machinery components in multiple myeloma (MM) cells and the impact of splicing modulation on tumor cell growth and viability. A comprehensive gene expression analysis confirmed the reported deregulation of spliceosome machinery components in MM cells, compared to normal plasma cells from healthy donors, with its pharmacological and genetic modulation resulting in impaired growth and survival of MM cell lines and patient-derived malignant plasma cells. Consistent with this, transcriptomic analysis revealed deregulation of BCL2 family members, including decrease of anti-apoptotic long form of myeloid cell leukemia-1 (MCL1) expression, as crucial for "priming" MM cells for Venetoclax activity in vitro and in vivo, irrespective of t(11;14) status. Overall, our data provide a rationale for supporting the clinical use of splicing modulators as a strategy to reprogram apoptotic dependencies and make all MM patients more vulnerable to BCL2 inhibitors.

Carfilzomib with cyclophosphamide and dexamethasone or lenalidomide and dexamethasone plus autologous transplantation or carfilzomib plus lenalidomide and dexamethasone, followed by maintenance with carfilzomib plus lenalidomide or lenalidomide alone for patients with newly diagnosed multiple myeloma (FORTE): a randomised, open-label, phase 2 trial.

BACKGROUND: Bortezomib-based induction followed by high-dose melphalan (200 mg/m2) and autologous stem-cell transplantation (MEL200-ASCT) and maintenance treatment with lenalidomide alone is the current standard of care for young and fit patients with newly diagnosed multiple myeloma. We aimed to evaluate the efficacy and safety of different carfilzomib-based induction and consolidation approaches with or without transplantation and of maintenance treatment with carfilzomib plus lenalidomide versus lenalidomide alone in newly diagnosed multiple myeloma. METHODS: UNITO-MM-01/FORTE was a randomised, open-label, phase 2 trial done in 42 Italian academic and community practice centres. We enrolled transplant-eligible patients with newly diagnosed multiple myeloma aged 65 years or younger with a Karnofsky Performance Status of 60% or higher. Patients were stratified according to International Staging System stage (I vs II/III) and age (<60 years vs 60-65 years) and randomly assigned (1:1:1) to KRd plus ASCT (four 28-day induction cycles with carfilzomib plus lenalidomide plus dexamethasone [KRd], melphalan at 200 mg/m2 and autologous stem-cell transplantation [MEL200-ASCT], followed by four 28-day KRd consolidation cycles), KRd12 (12 28-day KRd cycles), or KCd plus ASCT (four 28-day induction cycles with carfilzomib plus cyclophosphamide plus dexamethasone [KCd], MEL200-ASCT, and four 28-day KCd consolidation cycles). Carfilzomib 36 mg/m2 was administered intravenously on days 1, 2, 8, 9, 15, and 16; lenalidomide 25 mg administered orally on days 1-21; cyclophosphamide 300 mg/m2 administered orally on days 1, 8, and 15; and dexamethasone 20 mg administered orally or intravenously on days 1, 2, 8, 9, 15, 16, 22, and 23. Thereafter, patients were stratified according to induction-consolidation treatment and randomly assigned (1:1) to maintenance treatment with carfilzomib plus lenalidomide or lenalidomide alone. Carfilzomib 36 mg/m2 was administered intravenously on days 1-2 and 15-16 every 28 days for up to 2 years; lenalidomide 10 mg was administered orally on days 1-21 every 28 days until progression or intolerance in both groups. The primary endpoints were the proportion of patients with at least a very good partial response after induction with KRd versus KCd and progression-free survival with carfilzomib plus lenalidomide versus lenalidomide alone as maintenance treatment, both assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT02203643. Study recruitment is complete, and all patients are in the follow-up or maintenance phases. FINDINGS: Between Feb 23, 2015, and April 5, 2017, 474 patients were randomly assigned to one of the induction-intensification-consolidation groups (158 to KRd plus ASCT, 157 to KRd12, and 159 to KCd plus ASCT). The median duration of follow-up was 50·9 months (IQR 45·7-55·3) from the first randomisation. 222 (70%) of 315 patients in the KRd group and 84 (53%) of 159 patients in the KCd group had at least a very good partial response after induction (OR 2·14, 95% CI 1·44-3·19, p=0·0002). 356 patients were randomly assigned to maintenance treatment with carfilzomib plus lenalidomide (n=178) or lenalidomide alone (n=178). The median duration of follow-up was 37·3 months (IQR 32·9-41·9) from the second randomisation. 3-year progression-free survival was 75% (95% CI 68-82) with carfilzomib plus lenalidomide versus 65% (58-72) with lenalidomide alone (hazard ratio [HR] 0·64 [95% CI 0·44-0·94], p=0·023). During induction and consolidation, the most common grade 3-4 adverse events were neutropenia (21 [13%] of 158 patients in the KRd plus ASCT group vs 15 [10%] of 156 in the KRd12 group vs 18 [11%] of 159 in the KCd plus ASCT group); dermatological toxicity (nine [6%] vs 12 [8%] vs one [1%]); and hepatic toxicity (13 [8%] vs 12 [8%] vs none). Treatment-related serious adverse events were reported in 18 (11%) of 158 patients in the KRd-ASCT group, 29 (19%) of 156 in the KRd12 group, and 17 (11%) of 159 in the KCd plus ASCT group; the most common serious adverse event was pneumonia, in seven (4%) of 158, four (3%) of 156, and five (3%) of 159 patients. Treatment-emergent deaths were reported in two (1%) of 158 patients in the KRd plus ASCT group, two (1%) of 156 in the KRd12 group, and three (2%) of 159 in the KCd plus ASCT group. During maintenance, the most common grade 3-4 adverse events were neutropenia (35 [20%] of 173 patients on carfilzomib plus lenalidomide vs 41 [23%] of 177 patients on lenalidomide alone); infections (eight [5%] vs 13 [7%]); and vascular events (12 [7%] vs one [1%]). Treatment-related serious adverse events were reported in 24 (14%) of 173 patients on carfilzomib plus lenalidomide versus 15 (8%) of 177 on lenalidomide alone; the most common serious adverse event was pneumonia, in six (3%) of 173 versus five (3%) of 177 patients. One patient died of a treatment-emergent adverse event in the carfilzomib plus lenalidomide group. INTERPRETATION: Our data show that KRd plus ASCT showed superiority in terms of improved responses compared with the other two treatment approaches and support the prospective randomised evaluation of KRd plus ASCT versus standards of care (eg, daratumumab plus bortezomib plus thalidomide plus dexamethasone plus ASCT) in transplant-eligible patients with multiple myeloma. Carfilzomib plus lenalidomide as maintenance therapy also improved progression-free survival compared with the standard-of-care lenalidomide alone. FUNDING: Amgen, Celgene/Bristol Myers Squibb. TRANSLATION: For the Italian translation of the abstract see Supplementary Materials section.

A real-world efficacy and safety analysis of combined carfilzomib, lenalidomide, and dexamethasone (KRd) in relapsed/refractory multiple myeloma.

Carfilzomib-lenalidomide-dexamethasone (KRd) has been approved for the treatment of relapsed/refractory multiple myeloma (RRMM). We conducted a retrospective analysis of 197 RRMM patients (pts) between January 2016 and March 2018 in six Italian hematologic centers, with the aim to evaluate efficacy and safety of KRd in real-life. At KRd initiation 27% carried high risk cytogenetic abnormalities (HRCA) [del17p and/or t(4;14) and/or t(14;16)], median number of prior lines of therapy was 2 (1-8), nearly all pts (96%) received prior bortezomib (18% refractory) while 45% were exposed to lenalidomide (R; 22% refractory). At the median of 12.5 months, 52% of the pts had discontinued treatment, mainly (66%) for progression. Main grade 3-4 adverse events were neutropenia (21%), infections (11%), and hypertension (6%). Overall, the response rate was 88%. The median progression-free survival (PFS) was 19.8 months and 1-year overall survival (OS) rate was 80.6%. By subgroup analysis, extended PFS and OS were observed for pts who received ≤2 prior lines of therapy (HR = 0.42, p < 0.001 and HR = 0.35, p = 0.001, respectively), not refractory to prior R (HR = 0.37, p < 0.001, and HR = 0.47, p = 0.024), without HRCA (HR = 0.33, p = 0.005 and HR = 0.26, p = 0.016) and achieving ≥ very good partial response (VGPR; HR = 0.17, p < 0.001 and HR = 0.18, p < 0.001). In conclusion, KRd demonstrated to be effective in RRMM pts treated in real-world setting, without new safety concerns. Better survival outcomes emerged for pts with ≤2 prior lines of therapy, achieving at least a VGPR, and without HRCA.

Pre-transplant minimal residual disease assessment and transplant-related factors predict the outcome of acute myeloid leukemia patients undergoing allogeneic stem cell transplantation.

We studied pretransplant minimal residual disease (MRD) in 224 patients (median age 44 years; range 17-65) with acute myeloid leukemia (AML) undergoing allogeneic stem cell transplant (HSCT) in complete remission. MRD was evaluated on marrow samples using multicolor flow cytometry and assessment of WT1 gene expression. Both methods showed a strong prognostic value and their combination allowed the identification of three groups of patients with different risk of relapse. In multivariate analysis, combined MRD was the only predictor of cumulative incidence of relapse, regardless of donor type, conditioning regimen, first or second CR at HSCT, HSCT year, and ELN risk group. Multivariate regression model showed that only negative combined MRD status (P < .001) and myeloablative conditioning (P = .004) were independently associated with better OS. Among MRD-positive patients, a reduced incidence of relapse was observed in patients receiving haplo transplant (P < .05) and in patients who showed grade II-IV aGVHD (P < .03). In patients with negative combined MRD, the intensity of conditioning regimen did not affect the overall favorable outcome. We suggest that pretransplant MRD evaluation combined with transplant-related factors can identify AML patients at higher risk for relapse and might help in defining the overall transplant strategy.

The new small tyrosine kinase inhibitor ARQ531 targets acute myeloid leukemia cells by disrupting multiple tumor-addicted programs.

Tyrosine kinases have been implicated in promoting tumorigenesis of several human cancers. Exploiting these vulnerabilities has been shown to be an effective anti-tumor strategy as demonstrated for example by the Bruton's tyrosine kinase (BTK) inhibitor, ibrutinib, for treatment of various blood cancers. Here, we characterize a new multiple kinase inhibitor, ARQ531, and evaluate its mechanism of action in preclinical models of acute myeloid leukemia. Treatment with ARQ531, by producing global signaling pathway deregulation, resulted in impaired cell cycle progression and survival in a large panel of leukemia cell lines and patient-derived tumor cells, regardless of the specific genetic background and/or the presence of bone marrow stromal cells. RNA-seq analysis revealed that ARQ531 constrained tumor cell proliferation and survival through Bruton's tyrosine kinase and transcriptional program dysregulation, with proteasome-mediated MYB degradation and depletion of short-lived proteins that are crucial for tumor growth and survival, including ERK, MYC and MCL1. Finally, ARQ531 treatment was effective in a patient-derived leukemia mouse model with significant impairment of tumor progression and survival, at tolerated doses. These data justify the clinical development of ARQ531 as a promising targeted agent for the treatment of patients with acute myeloid leukemia.

SIRT6 deacetylase activity regulates NAMPT activity and NAD(P)(H) pools in cancer cells.

Nicotinamide phosphoribosyltransferase (NAMPT) is the rate-limiting enzyme in the NAD+ salvage pathway from nicotinamide. By controlling the biosynthesis of NAD+, NAMPT regulates the activity of NAD+-converting enzymes, such as CD38, poly-ADP-ribose polymerases, and sirtuins (SIRTs). SIRT6 is involved in the regulation of a wide number of metabolic processes. In this study, we investigated the ability of SIRT6 to regulate intracellular NAMPT activity and NAD(P)(H) levels. BxPC-3 cells and MCF-7 cells were engineered to overexpress a catalytically active or a catalytically inactive SIRT6 form or were engineered to silence endogenous SIRT6 expression. In SIRT6-overexpressing cells, NAD(H) levels were up-regulated, as a consequence of NAMPT activation. By immunopurification and incubation with recombinant SIRT6, NAMPT was found to be a direct substrate of SIRT6 deacetylation, with a mechanism that up-regulates NAMPT enzymatic activity. Extracellular NAMPT release was enhanced in SIRT6-silenced cells. Also glucose-6-phosphate dehydrogenase activity and NADPH levels were increased in SIRT6-overexpressing cells. Accordingly, increased SIRT6 levels reduced cancer cell susceptibility to H2O2-induced oxidative stress and to doxorubicin. Our data demonstrate that SIRT6 affects intracellular NAMPT activity, boosts NAD(P)(H) levels, and protects against oxidative stress. The use of SIRT6 inhibitors, together with agents inducing oxidative stress, may represent a promising treatment strategy in cancer.-Sociali, G., Grozio, A., Caffa, I., Schuster, S., Becherini, P., Damonte, P., Sturla, L., Fresia, C., Passalacqua, M., Mazzola, F., Raffaelli, N., Garten, A., Kiess, W., Cea, M., Nencioni, A., Bruzzone, S. SIRT6 deacetylase activity regulates NAMPT activity and NAD(P)(H) pools in cancer cells.

Functional role and therapeutic targeting of p21-activated kinase 4 in multiple myeloma.

Dysregulated oncogenic serine/threonine kinases play a pathological role in diverse forms of malignancies, including multiple myeloma (MM), and thus represent potential therapeutic targets. Here, we evaluated the biological and functional role of p21-activated kinase 4 (PAK4) and its potential as a new target in MM for clinical applications. PAK4 promoted MM cell growth and survival via activation of MM survival signaling pathways, including the MEK-extracellular signal-regulated kinase pathway. Furthermore, treatment with orally bioavailable PAK4 allosteric modulator (KPT-9274) significantly impacted MM cell growth and survival in a large panel of MM cell lines and primary MM cells alone and in the presence of bone marrow microenvironment. Intriguingly, we have identified FGFR3 as a novel binding partner of PAK4 and observed significant activity of KPT-9274 against t(4;14)-positive MM cells. This set of data supports PAK4 as an oncogene in myeloma and provide the rationale for the clinical evaluation of PAK4 modulator in myeloma.

APRIL and BCMA promote human multiple myeloma growth and immunosuppression in the bone marrow microenvironment.

Here we show that overexpression or activation of B-cell maturation antigen (BCMA) by its ligand, a proliferation-inducing ligand (APRIL), promotes human multiple myeloma (MM) progression in vivo. BCMA downregulation strongly decreases viability and MM colony formation; conversely, BCMA overexpression augments MM cell growth and survival via induction of protein kinase B (AKT), MAPK, and nuclear factor (NF)-κB signaling cascades. Importantly, BCMA promotes in vivo growth of xenografted MM cells harboring p53 mutation in mice. BCMA-overexpressing tumors exhibit significantly increased CD31/microvessel density and vascular endothelial growth factor compared with paired control tumors. These tumors also express increased transcripts crucial for osteoclast activation, adhesion, and angiogenesis/metastasis, as well as genes mediating immune inhibition including programmed death ligand 1, transforming growth factor ß, and interleukin 10. These target genes are consistently induced by paracrine APRIL binding to BCMA on MM cells, which is blocked by an antagonistic anti-APRIL monoclonal antibody hAPRIL01A (01A). 01A is cytotoxic against MM cells even in the presence of protective bone marrow (BM) myeloid cells including osteoclasts, macrophages, and plasmacytoid dendritic cells. 01A further decreases APRIL-induced adhesion and migration of MM cells via blockade of canonical and noncanonical NF-κB pathways. Moreover, 01A prevents in vivo MM cell growth within implanted human bone chips in SCID mice. Finally, the effect of 01A on MM cell viability is enhanced by lenalidomide and bortezomib. Taken together, these data delineate new molecular mechanisms of in vivo MM growth and immunosuppression critically dependent on BCMA and APRIL in the BM microenvironment, further supporting targeting this prominent pathway in MM.

Evidence for a role of the histone deacetylase SIRT6 in DNA damage response of multiple myeloma cells.

Multiple myeloma (MM) is characterized by a highly unstable genome, with aneuploidy observed in nearly all patients. The mechanism causing this karyotypic instability is largely unknown, but recent observations have correlated these abnormalities with dysfunctional DNA damage response. Here, we show that the NAD(+)-dependent deacetylase SIRT6 is highly expressed in MM cells, as an adaptive response to genomic stability, and that high SIRT6 levels are associated with adverse prognosis. Mechanistically, SIRT6 interacts with the transcription factor ELK1 and with the ERK signaling-related gene. By binding to their promoters and deacetylating H3K9 at these sites, SIRT6 downregulates the expression of mitogen-activated protein kinase (MAPK) pathway genes, MAPK signaling, and proliferation. In addition, inactivation of ERK2/p90RSK signaling triggered by high SIRT6 levels increases DNA repair via Chk1 and confers resistance to DNA damage. Using genetic and biochemical studies in vitro and in human MM xenograft models, we show that SIRT6 depletion both enhances proliferation and confers sensitization to DNA-damaging agents. Our findings therefore provide insights into the functional interplay between SIRT6 and DNA repair mechanisms, with implications for both tumorigenesis and the treatment of MM.

Depletion of SIRT6 enzymatic activity increases acute myeloid leukemia cells' vulnerability to DNA-damaging agents.

Genomic instability plays a pathological role in various malignancies, including acute myeloid leukemia (AML), and thus represents a potential therapeutic target. Recent studies demonstrate that SIRT6, a NAD+-dependent nuclear deacetylase, functions as genome-guardian by preserving DNA integrity in different tumor cells. Here, we demonstrate that also CD34+ blasts from AML patients show ongoing DNA damage and SIRT6 overexpression. Indeed, we identified a poor-prognostic subset of patients, with widespread instability, which relies on SIRT6 to compensate for DNA-replication stress. As a result, SIRT6 depletion compromises the ability of leukemia cells to repair DNA double-strand breaks that, in turn, increases their sensitivity to daunorubicin and Ara-C, both in vitro and in vivo In contrast, low SIRT6 levels observed in normal CD34+ hematopoietic progenitors explain their weaker sensitivity to genotoxic stress. Intriguingly, we have identified DNA-PKcs and CtIP deacetylation as crucial for SIRT6-mediated DNA repair. Together, our data suggest that inactivation of SIRT6 in leukemia cells leads to disruption of DNA-repair mechanisms, genomic instability and aggressive AML. This synthetic lethal approach, enhancing DNA damage while concomitantly blocking repair responses, provides the rationale for the clinical evaluation of SIRT6 modulators in the treatment of leukemia.

Pharmacological Sirt6 inhibition improves glucose tolerance in a type 2 diabetes mouse model.

Sirtuin 6 (SIRT6) is a sirtuin family member involved in a wide range of physiologic and disease processes, including cancer and glucose homeostasis. Based on the roles played by SIRT6 in different organs, including its ability to repress the expression of glucose transporters and glycolytic enzymes, inhibiting SIRT6 has been proposed as an approach for treating type 2 diabetes mellitus (T2DM). However, so far, the lack of small-molecule Sirt6 inhibitors has hampered the conduct of in vivo studies to assess the viability of this strategy. We took advantage of a recently identified SIRT6 inhibitor, compound 1, to study the effect of pharmacological Sirt6 inhibition in a mouse model of T2DM (i.e., in high-fat-diet-fed animals). The administration of the Sirt6 inhibitor for 10 d was well tolerated and improved oral glucose tolerance, it increased the expression of the glucose transporters GLUT1 and -4 in the muscle and enhanced the activity of the glycolytic pathway. Sirt6 inhibition also resulted in reduced insulin, triglycerides, and cholesterol levels in plasma. This study represents the first in vivo study of a SIRT6 inhibitor and provides the proof-of-concept that targeting SIRT6 may be a viable strategy for improving glycemic control in T2DM.-Sociali, G., Magnone, M., Ravera, S., Damonte, P., Vigliarolo, T., Von Holtey, M., Vellone, V. G., Millo, E., Caffa, I., Cea, M., Parenti, M. D., Del Rio, A., Murone, M., Mostoslavsky, R., Grozio, A., Nencioni, A., Bruzzone S. Pharmacological Sirt6 inhibition improves glucose tolerance in a type 2 diabetes mouse model.

SIRT6 inhibitors with salicylate-like structure show immunosuppressive and chemosensitizing effects.

The NAD+-dependent deacetylase SIRT6 is an emerging cancer drug target, whose inhibition sensitizes cancer cells to chemo-radiotherapy and has pro-differentiating effects. Here we report on the identification of novel SIRT6 inhibitors with a salicylate-based structure. The new SIRT6 inhibitors show improved potency and specificity compared to the hit inhibitor identified in an in silico compound screen. As predicted based on SIRT6 biological roles, the new leads increase histone 3 lysine 9 acetylation and glucose uptake in cultured cells, while blocking TNF-α production and T lymphocyte proliferation. Notably, the new SIRT6 inhibitors effectively sensitize pancreatic cancer cells to gemcitabine. Finally, studies of compound fingerprinting and pharmacokinetics defined the drug-like properties of one of the new SIRT6 inhibitors, potentially allowing for subsequent in vivo proof-of-concept studies. In conclusion, new SIRT6 inhibitors with a salicylate-like structure were identified, which are active in cells and could potentially find applications in disease conditions, including cancer and immune-mediated disorders.

Novel anti-B-cell maturation antigen antibody-drug conjugate (GSK2857916) selectively induces killing of multiple myeloma.

B-cell maturation antigen (BCMA), highly expressed on malignant plasma cells in human multiple myeloma (MM), has not been effectively targeted with therapeutic monoclonal antibodies. We here show that BCMA is universally expressed on the MM cell surface and determine specific anti-MM activity of J6M0-mcMMAF (GSK2857916), a novel humanized and afucosylated antagonistic anti-BCMA antibody-drug conjugate via a noncleavable linker. J6M0-mcMMAF specifically blocks cell growth via G2/M arrest and induces caspase 3-dependent apoptosis in MM cells, alone and in coculture with bone marrow stromal cells or various effector cells. It strongly inhibits colony formation by MM cells while sparing surrounding BCMA-negative normal cells. J6M0-mcMMAF significantly induces effector cell-mediated lysis against allogeneic or autologous patient MM cells, with increased potency and efficacy compared with the wild-type J6M0 without Fc enhancement. The antibody-dependent cell-mediated cytotoxicity and apoptotic activity of J6M0-mcMMAF is further enhanced by lenalidomide. Importantly, J6M0-mcMMAF rapidly eliminates myeloma cells in subcutaneous and disseminated mouse models, and mice remain tumor-free up to 3.5 months. Furthermore, J6M0-mcMMAF recruits macrophages and mediates antibody-dependent cellular phagocytosis of MM cells. Together, these results demonstrate that GSK2857916 has potent and selective anti-MM activities via multiple cytotoxic mechanisms, providing a promising next-generation immunotherapeutic in this cancer.

Intraplaque Expression of C-Reactive Protein Predicts Cardiovascular Events in Patients with Severe Atherosclerotic Carotid Artery Stenosis.

Serum c-reactive protein (CRP) was suggested for the assessment of intermediate cardiovascular (CV) risk. Here, systemic or intraplaque CRP levels were investigated as predictors of major adverse cardiovascular events (MACEs) in patients with severe carotid stenosis. CRP levels were assessed in the serum and within different portions (upstream and downstream) of carotid plaques of 217 patients undergoing endarterectomy. The association between CRP and intraplaque lipids, collagen, neutrophils, smooth muscle cells (SMC), and macrophage subsets was determined. No correlation between serum CRP and intraplaque biomarkers was observed. In upstream portions, CRP content was directly correlated with intraplaque neutrophils, total macrophages, and M1 macrophages and inversely correlated with SMC content. In downstream portions, intraplaque CRP correlated with M1 and M2 macrophages. According to the cut-off point (CRP > 2.9%) identified by ROC analysis in upstream portions, Kaplan-Meier analysis showed that patients with high CRP levels had a greater rate of MACEs. This risk of MACEs increased independently of age, male gender, serum CRP, and statin use. In conclusion, in patients with severe carotid artery stenosis, high CRP levels within upstream portions of carotid plaques directly and positively correlate with intraplaque inflammatory cells and predict MACEs at an 18-month follow-up period.