Samantha Pozzi

Pharmacologic targeting of a stem/progenitor population in vivo is associated with enhanced bone regeneration in mice.

Drug targeting of adult stem cells has been proposed as a strategy for regenerative medicine, but very few drugs are known to target stem cell populations in vivo. Mesenchymal stem/progenitor cells (MSCs) are a multipotent population of cells that can differentiate into muscle, bone, fat, and other cell types in context-specific manners. Bortezomib (Bzb) is a clinically available proteasome inhibitor used in the treatment of multiple myeloma. Here, we show that Bzb induces MSCs to preferentially undergo osteoblastic differentiation, in part by modulation of the bone-specifying transcription factor runt-related transcription factor 2 (Runx-2) in mice. Mice implanted with MSCs showed increased ectopic ossicle and bone formation when recipients received low doses of Bzb. Furthermore, this treatment increased bone formation and rescued bone loss in a mouse model of osteoporosis. Thus, we show that a tissue-resident adult stem cell population in vivo can be pharmacologically modified to promote a regenerative function in adult animals.

ABVD Compared With BEACOPP Compared With CEC for the Initial Treatment of Patients With Advanced Hodgkin's Lymphoma: Results From the HD2000 Gruppo Italiano per lo Studio dei Linfomi Trial

PURPOSE To compare doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD) versus bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (BEACOPP) versus cyclophosphamide, lomustine, vindesine, melphalan, prednisone, epidoxirubicin, vincristine, procarbazine, vinblastine, and bleomycin (COPPEBVCAD; CEC) for advanced Hodgkins lymphoma (HL). PATIENTS AND METHODS Three hundred seven patients with advanced HL (stage IIB, III, and IV) were randomly assigned to receive six courses of ABVD, four escalated plus two standard courses of BEACOPP, or six courses of CEC, plus a limited radiation therapy program. RESULTS After a median follow-up of 41 months, BEACOPP resulted in a superior progression-free survival (PFS), with a significant reduction in risk of progression (hazard ratio [HR] = 0.50) compared with ABVD. No differences between BEACOPP and CEC, or CEC and ABVD were observed. The 5-year PFS was 68% (95% CI, 56% to 78%), 81% (95% CI, 70% to 89%), and 78% (95% CI, 68% to 86%), for ABVD, BEACOPP, and CEC, respectively (BEACOPP v ABVD, P = .038; CEC v ABVD and BEACOPP v CEC, P = not significant [NS]). The 5-year overall survival was 84% (95% CI, 69% to 92%), 92% (95% CI, 84% to 96%), and 91% (95% CI, 81% to 96%) for ABVD, BEACOPP, and CEC, respectively (P = NS). BEACOPP and CEC resulted in higher rates of grade 3-4 neutropenia than ABVD (P = .016); BEACOPP was associated with higher rates of severe infections than ABVD and CEC (P = .003). CONCLUSION As adopted in this study BEACOPP is associated with a significantly improved PFS compared with ABVD, with a predictable higher acute toxicity.

Activin A promotes multiple myeloma-induced osteolysis and is a promising target for myeloma bone disease

Understanding the pathogenesis of cancer-related bone disease is crucial to the discovery of new therapies. Here we identify activin A, a TGF-β family member, as a therapeutically amenable target exploited by multiple myeloma (MM) to alter its microenvironmental niche favoring osteolysis. Increased bone marrow plasma activin A levels were found in MM patients with osteolytic disease. MM cell engagement of marrow stromal cells enhanced activin A secretion via adhesion-mediated JNK activation. Activin A, in turn, inhibited osteoblast differentiation via SMAD2-dependent distal-less homeobox–5 down-regulation. Targeting activin A by a soluble decoy receptor reversed osteoblast inhibition, ameliorated MM bone disease, and inhibited tumor growth in an in vivo humanized MM model, setting the stage for testing in human clinical trials.

The Monoclonal Antibody nBT062 Conjugated to Cytotoxic Maytansinoids Has Selective Cytotoxicity Against CD138-Positive Multiple Myeloma Cells In vitro and In vivo

Purpose: We investigated the antitumor effect of murine/human chimeric CD138-specific monoclonal antibody nBT062 conjugated with highly cytotoxic maytansinoid derivatives against multiple myeloma (MM) cells in vitro and in vivo. Experimental Design: We examined the growth inhibitory effect of BT062-SPDB-DM4, BT062-SMCC-DM1, and BT062-SPP-DM1 against MM cell lines and primary tumor cells from MM patients. We also examined in vivo activity of these agents in murine MM cell xenograft model of human and severe combined immunodeficient (SCID) mice bearing implant bone chips injected with human MM cells (SCID-hu model). Results: Anti-CD138 immunoconjugates significantly inhibited growth of MM cell lines and primary tumor cells from MM patients without cytotoxicity against peripheral blood mononuclear cells from healthy volunteers. In MM cells, they induced G2-M cell cycle arrest, followed by apoptosis associated with cleavage of caspase-3, caspase-8, caspase-9, and poly(ADP-ribose) polymerase. Nonconjugated nBT062 completely blocked cytotoxicity induced by nBT062-maytansinoid conjugate, confirming that specific binding is required for inducing cytotoxicity. Moreover, nBT062-maytansinoid conjugates blocked adhesion of MM cells to bone marrow stromal cells. The coculture of MM cells with bone marrow stromal cells protects against dexamethasone-induced death but had no effect on the cytotoxicity of immunoconjugates. Importantly, nBT062-SPDB-DM4 and nBT062-SPP-DM1 significantly inhibited MM tumor growth in vivo and prolonged host survival in both the xenograft mouse models of human MM and SCID-hu mouse model. Conclusion: These results provide the preclinical framework supporting evaluation of nBT062-maytansinoid derivatives in clinical trials to improve patient outcome in MM.

Dual inhibition of akt/mammalian target of rapamycin pathway by nanoparticle albumin-bound-rapamycin and perifosine induces antitumor activity in multiple myeloma.

The phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway mediates multiple myeloma (MM) cell proliferation, survival, and development of drug resistance, underscoring the role of mTOR inhibitors, such as rapamycin, with potential anti-MM activity. However, recent data show a positive feedback loop from mTOR/S6K1 to Akt, whereby Akt activation confers resistance to mTOR inhibitors. We confirmed that suppression of mTOR signaling in MM cells by rapamycin was associated with upregulation of Akt phosphorylation. We hypothesized that inhibiting this positive feedback by a potent Akt inhibitor perifosine would augment rapamycin-induced cytotoxicity in MM cells. Perifosine inhibited rapamycin-induced phosphorylated Akt, resulting in enhanced cytotoxicity in MM.1S cells even in the presence of interleukin-6, insulin-like growth factor-I, or bone marrow stromal cells. Moreover, rapamycin-induced autophagy in MM.1S MM cells, as evidenced by electron microscopy and immunocytochemistry, was augmented by perifosine. Combination therapy increased apoptosis detected by Annexin V/propidium iodide analysis and caspase/poly(ADP-ribose) polymerase cleavage. Importantly, in vivo antitumor activity and prolongation of survival in a MM mouse xenograft model after treatment was enhanced with combination of nanoparticle albumin-bound–rapamycin and perifosine. Utilizing the in silico predictive analysis, we confirmed our experimental findings of this drug combination on PI3K, Akt, mTOR kinases, and the caspases. Our data suggest that mutual suppression of the PI3K/Akt/mTOR pathway by rapamycin and perifosine combination induces synergistic MM cell cytotoxicity, providing the rationale for clinical trials in patients with relapsed/refractory MM. Mol Cancer Ther; 9(4); 963–75. ©2010 AACR.

5-Azacytidine, a DNA methyltransferase inhibitor, induces ATR-mediated DNA double-strand break responses, apoptosis, and synergistic cytotoxicity with doxorubicin and bortezomib against multiple myeloma cells

In this study, we investigated the cytotoxicity of 5-azacytidine, a DNA methyltransferase inhibitor, against multiple myeloma (MM) cells, and characterized DNA damage–related mechanisms of cell death. 5-Azacytidine showed significant cytotoxicity against both conventional therapy-sensitive and therapy-resistant MM cell lines, as well as multidrug-resistant patient-derived MM cells, with IC50 of ∼0.8–3 μmol/L. Conversely, 5-azacytidine was not cytotoxic to peripheral blood mononuclear cells or patient-derived bone marrow stromal cells (BMSC) at these doses. Importantly, 5-azacytidine overcame the survival and growth advantages conferred by exogenous interleukin-6 (IL-6), insulin-like growth factor-I (IGF-I), or by adherence of MM cells to BMSCs. 5-Azacytidine treatment induced DNA double-strand break (DSB) responses, as evidenced by H2AX, Chk2, and p53 phosphorylations, and apoptosis of MM cells. 5-Azacytidine–induced apoptosis was both caspase dependent and independent, with caspase 8 and caspase 9 cleavage; Mcl-1 cleavage; Bax, Puma, and Noxa up-regulation; as well as release of AIF and EndoG from the mitochondria. Finally, we show that 5-azacytidine–induced DNA DSB responses were mediated predominantly by ATR, and that doxorubicin, as well as bortezomib, synergistically enhanced 5-azacytidine–induced MM cell death. Taken together, these data provide the preclinical rationale for the clinical evaluation of 5-azacytidine, alone and in combination with doxorubicin and bortezomib, to improve patient outcome in MM. [Mol Cancer Ther 2007;6(6):1718–27]

A High-Affinity Fully Human Anti–IL-6 mAb, 1339, for the Treatment of Multiple Myeloma

Purpose: We investigated the in vitro and in vivo anti-multiple myeloma activity of monoclonal antibody (mAb) 1339, a high-affinity fully humanized anti-interleukin 6 mAb (immunoglobulin G1), alone and in combination with conventional and novel anti-multiple myeloma agents, as well as its effect on bone turnover. Experimental Design: We examined the growth inhibitory effect of 1339 against multiple myeloma cell lines in the absence and in the presence of bone marrow stromal cells, alone or in combination with dexamethasone, bortezomib, perifosine, and Revlimid. Using the severe combined immunodeficient (SCID)–hu murine model of multiple myeloma, we also examined the effect of 1339 on multiple myeloma cell growth and multiple myeloma bone disease. Results: mAb 1339 significantly inhibited growth of multiple myeloma cell in the presence of bone marrow stromal cell in vitro, associated with inhibition of phosphorylation of signal transducer and activator of transcription 3, extracellular signal-regulated kinase 1/2, and Akt. In addition, mAb 1339 enhanced cytotoxicity induced by dexamethasone, as well as bortezomib, lenalidomide, and perifosine, in a synergistic fashion. Importantly mAb 1339 significantly enhanced growth inhibitory effects of dexamethasone in vivo in SCID-hu mouse model of multiple myeloma. mAb 1339 treatment also resulted in inhibition of osteoclastogenesis in vitro and bone remodeling in SCID-hu model. Conclusions: Our data confirm in vitro and in vivo anti-multiple myeloma activity of, as well as inhibition of bone turnover by, fully humanized mAb 1339, as a single agent and in combination with conventional and novel agents, providing a rationale for its clinical evaluation in multiple myeloma. (Clin Cancer Res 2009;15(23):7144–52)

Bisphosphonate-associated osteonecrosis of the jaw: A review of 35 cases and an evaluation of its frequency in multiple myeloma patients

Over a period of 28 months, we observed five cases of osteonecrosis of the jaw (ONJ) in cancer patients treated with bisphosphonates (BP) at our institution. This prompted us to undertake a retrospective, multicenter study to analyse the characteristics of patients who exhibited ONJ and to define the frequency of ONJ in multiple myeloma (MM). We identified 35 cases in Gruppo Italiano Studio Linfomi centers during the period 2002 – 05. The median time from cancer diagnosis to the clinical onset of ONJ was 70 months. In these 35 cases of ONJ, 24 appeared 20 – 60 months after starting BP treatment. The time for the onset of ONJ was significantly shorter for patients treated with zoledronic acid alone than for those treated with pamidronate followed by zoledronic acid. The frequency of ONJ in the MM group during the study period was 1.9%, although the nature of the present study may have resulted in an underestimation of ONJ cases. Our analysis strongly suggested an association between the use of BP and the occurrence of ONJ, although we were unable to identify any definite risk factors with a retrospective study. The most frequently ONJ-associated clinical characteristics were chemotherapy treatment, steroid treatment, advanced age, female sex, anemia, parodonthopaties/dental procedures and thalidomide (in the case of MM patients).

A Novel Role for CCL3 (MIP-1α) in Myeloma-induced Bone Disease via Osteocalcin Downregulation and Inhibition of Osteoblast Function

Upregulation of cytokines and chemokines is a frequent finding in multiple myeloma (MM). CCL3 (also known as MIP-1α) is a pro-inflammatory chemokine, levels of which in the MM microenvironment correlate with osteolytic lesions and tumor burden. CCL3 and its receptors, CCR1 and CCR5, contribute to the development of bone disease in MM by supporting tumor growth and regulating osteoclast (OC) differentiation. In this study, we identify inhibition of osteoblast (OB) function as an additional pathogenic mechanism in CCL3-induced bone disease. MM-derived and exogenous CCL3 represses mineralization and osteocalcin production by primary human bone marrow stromal cells and HS27A cells. Our results suggest that CCL3 effects on OBs are mediated by ERK activation and subsequent downregulation of the osteogenic transcription factor osterix. CCR1 inhibition reduced ERK phosphorylation and restored both osterix and osteocalcin expression in the presence of CCL3. Finally, treating SCID-hu mice with a small molecule CCR1 inhibitor suggests an upregulation of osteocalcin expression along with OC downregulation. Our results show that CCL3, in addition to its known catabolic activity, reduces bone formation by inhibiting OB function, and therefore contributes to OB/OC uncoupling in MM.

Secondary malignancies after treatment for indolent non-Hodgkin’s lymphoma: a 16-year follow-up study

There is relatively little information on secondary cancers after non-Hodgkin’s lymphomas. This long-term follow-up study determines the incidence rate and identifies subgroups of non-Hodgkins lymphoma patients with increased incidences of secondary malignancy. Background Relatively little information is available on the incidence of secondary cancer in non-Hodgkin’s lymphoma. The aim of this long-term follow-up study was to determine the incidence, the time free of second tumors, and risk factors for developing secondary cancer in a homogeneous group of patients with non-Hodgkin’s lymphoma. Design and Methods We evaluated a total of 563 patients with indolent non-Hodgkin’s lymphoma enrolled in Gruppo Italiano Studio Linfomi trials from 1988 to 2003. Results After a median follow-up of 62 months, 39 patients (6.9%) developed secondary cancer: 12 myelodysplastic syndromes/acute myeloid leukemia, and 27 solid tumors. The overall standardized incidence ratio of secondary malignancy in patients with non-Hodgkin’s lymphoma was higher than the risk of malignancy in the general population. The standardized incidence ratio was elevated in male patients and in patients under 65 years old at first treatment. Overall, the cumulative incidence of secondary cancer at 12 years was 10.5%, after correction in a competing-risk model. Univariate and multivariate Cox regression analyses showed that older age at the time of diagnosis, male sex, and fludarabine-containing therapy had significant negative impacts on the time free of second tumors. Conclusions We have identified subgroups of non-Hodgkin’s lymphoma patients with increased standardized incidence ratios of secondary malignancy and variables that have a negative impact on the time free of second tumors. This information could help physicians to select the most appropriate treatments. Finally, taking into account the possible occurrence of secondary neoplasia, long-term monitoring must be considered.