Luca Paoluzzi

Targeting Bcl-2 family members with the BH3 mimetic AT-101 markedly enhances the therapeutic effects of chemotherapeutic agents in in vitro and in vivo models of B-cell lymphoma

Overexpression of antiapoptotic members of the Bcl-2 family are observed in approximately 80% of B-cell lymphomas, contributing to intrinsic and acquired drug resistance. Nullifying antiapoptotic function can potentially overcome this in-trinsic and acquired drug resistance. AT-101 is a BH3 mimetic known to be a potent inhibitor of antiapoptotic Bcl-2 family members including Bcl-2, Bcl-X(L), and Mcl-1. In vitro, AT-101 exhibits concentration- and time-dependent cytotoxicity against lymphoma and multiple myeloma cell lines, enhancing the activity of cytotoxic agents. The IC(50) for AT-101 is between 1 and 10 microM for a diverse panel of B-cell lymphomas. AT-101 was synergistic with carfilzomib (C), etoposide (E), doxorubicin (D), and 4-hydroxycyclophosphamide (4-HC) in mantle cell lymphoma (MCL) lines. In a transformed large B-cell lymphoma line (RL), AT-101 was synergistic when sequentially combined with 4-HC, but not when both drugs were added simultaneously. AT-101 also induced potent mitochondrial membrane depolarization (Delta Psi m) and apoptosis when combined with carfilzomib, but not with bortezomib in MCL. In severe combined immunodeficient (SCID) beige mouse models of drug-resistant B-cell lymphoma, 35 mg/kg per day of AT-101 was safe and efficacious. The addition of AT-101 to cyclophosphamide (Cy) and rituximab (R) in a schedule-dependent manner enhanced the efficacy of the conventional therapy.

The BH3-only mimetic ABT-737 synergizes the antineoplastic activity of proteasome inhibitors in lymphoid malignancies

Overexpression of antiapoptotic members of the Bcl-2 family is observed in approximately 80% of B-cell lymphomas, contributing to intrinsic and acquired drug resistance. Nullifying the antiapoptotic influence of these proteins can potentially overcome this resistance, and may complement conventional chemotherapy. ABT-737 is a BH3-only mimetic and potent inhibitor of the antiapoptotic Bcl-2 family members Bcl-2, Bcl-X(L), and Bcl-w. In vitro, ABT-737 exhibited concentration-dependent cytotoxicity against a broad panel of lymphoma cell lines including mantle cell lymphoma (MCL) and diffuse large B-cell lymphoma (DLBCL). ABT-737 showed synergism when combined with the proteasome inhibitors bortezomib or carfilzomib in select lymphoma cell lines and induced potent mitochondrial membrane depolarization and apoptosis when combined with either. ABT-737 plus bortezomib also induced significant apoptosis in primary samples of MCL, DLBCL, and chronic lymphocytic leukemia (CLL) but no significant cytotoxic effect was observed in peripheral blood mononuclear cells from healthy donors. In severe combined immunodeficient beige mouse models of MCL, the addition of ABT-737 to bortezomib enhanced efficacy compared with either drug alone and with the control. Collectively, these data suggest that ABT-737 alone or in combination with a proteasome inhibitor represents a novel and potentially important platform for the treatment of B-cell malignancies.

Romidepsin and Belinostat Synergize the Antineoplastic Effect of Bortezomib in Mantle Cell Lymphoma

Purpose: Romidepsin and belinostat are inhibitors of histone deacetylases (HDACI). HDACIs are known to induce cell death in malignant cells through multiple mechanisms, including upregulation of death receptors and induction of cell cycle arrest. They are also known to be prodifferentiating. Mantle cell lymphoma (MCL) is an aggressive subtype of non–Hodgkin lymphoma characterized by the t(11;14)(q13;q32) translocation leading to the overexpression of cyclin D1. Experimental Design: Assays for cytotoxicty including mathematical analysis for synergism, flow-cytometry, immunoblottings, and a xenograft severe combined immunodeficient beige mouse model were used to explore the in vitro and in vivo activity of romidepsin and/or belinostat alone or in combination with the proteasome inhibitor bortezomib in MCL. Results: In vitro, romidepsin and belinostat exhibited concentration-dependent cytotoxicity against a panel of MCL cell lines. Both HDACI showed strong synergism when combined with the proteasome inhibitor bortezomib in MCL. An HDACI plus bortezomib also induced potent mitochondrial membrane depolarization and apoptosis, whereas no significant apoptosis was observed in peripheral blood mononuclear cells from healthy donors with the combination. These events were associated with a decrease in cyclin D1 and Bcl-XL, and an increase in accumulation of acetylated histone H3, acetylated α-tubulin, and Noxa in cell lines. In a severe combined immunodeficient beige mouse model of MCL, the addition of belinostat to bortezomib enhanced efficacy compared with either drug alone. Conclusions: Collectively, these data strongly suggest that HDACI such as romidepsin or belinostat in combination with a proteasome inhibitor could represent a novel and rationale platform for the treatment of MCL. Clin Cancer Res; 16(2); 554–65

Pralatrexate is Synergistic with the Proteasome Inhibitor Bortezomib in In Vitro and In Vivo Models of T-Cell Lymphoid Malignancies

Purpose: Pralatrexate (10-propargyl-10-deazaaminopterin) is an antifolate with improved cellular uptake and retention due to greater affinity for the reduced folate carrier (RFC-1) and folyl-polyglutamyl synthase. Based on the PROPEL data, pralatrexate was the first drug approved for patients with relapsed and refractory peripheral T-cell lymphoma. Bortezomib is a proteasome inhibitor that has shown some activity in patients with T-cell lymphoma. Experimental Design: Assays for cytotoxicity including mathematical analysis for synergism, flow cytometry, immunoblotting, and a xenograft severe combined immunodeficient-beige mouse model were used to explore the in vitro and in vivo activities of pralatrexate alone and in combination with bortezomib in T-cell lymphoid malignancies. Results: In vitro, pralatrexate and bortezomib exhibited concentration- and time-dependent cytotoxicity against a broad panel of T-lymphoma cell lines. Pralatrexate showed synergism when combined with bortezomib in all cell lines studied. Pralatrexate also induced potent apoptosis and caspase activation when combined with bortezomib across the panel. Cytotoxicity studies on normal peripheral blood mononuclear cells showed that the combination was not more toxic than the single agents. Western blot assays for proteins involved in broad growth and survival pathways showed that p27, NOXA, HH3, and RFC-1 were all significantly modulated by the combination. In a severe combined immunodeficient-beige mouse model of transformed cutaneous T-cell lymphoma, the addition of pralatrexate to bortezomib enhanced efficacy compared with either drug alone. Conclusion: Collectively, these data suggest that pralatrexate in combination with bortezomib represents a novel and potentially important platform for the treatment of T-cell malignancies. Clin Cancer Res; 16(14); 3648–58. ©2010 AACR.

The anti‐histaminic cyproheptadine synergizes the antineoplastic activity of bortezomib in mantle cell lymphoma through its effects as a histone deacetylase inhibitor

Cyproheptadine, an inhibitor of the H1 histamine receptors, has recently shown activity in models of leukaemia and myeloma, presumably through inhibition of cyclin‐D expression. Mantle cell lymphoma (MCL) is an aggressive subtype of non‐Hodgkin lymphoma characterized by overexpression of cyclin‐D1. We investigated the effect of cyproheptadine alone and in combination with the proteasome inhibitor bortezomib in models of MCL. The combination of these drugs was mathematically synergistic, producing significant reductions in the mitochondrial membrane potential leading to apoptosis. In a severe combined immunodeficient beige mouse model, cyproheptadine plus bortezomib demonstrated a statistically significant advantage compared to either agent alone.

BET and BRAF inhibitors act synergistically against BRAF‐mutant melanoma

Despite major advances in the treatment of metastatic melanoma, treatment failure is still inevitable in most cases. Manipulation of key epigenetic regulators, including inhibition of Bromodomain and extra‐terminal domain (BET) family members impairs cell proliferation in vitro and tumor growth in vivo in different cancers, including melanoma. Here, we investigated the effect of combining the BET inhibitor JQ1 with the BRAF inhibitor Vemurafenib in in vitro and in vivo models of BRAF‐mutant melanoma. We performed cytotoxicity and apoptosis assays, and a xenograft mouse model to determine the in vitro and in vivo efficacy of JQ1 in combination with Vemurafenib against BRAF‐mutant melanoma cell lines. Further, to investigate the molecular mechanisms underlying the effects of combined treatment, we conducted antibody arrays of in vitro drug‐treated cell lines and RNA sequencing of drug‐treated xenograft tumors. The combination of JQ1 and Vemurafenib acted synergistically in BRAF‐mutant cell lines, resulting in marked apoptosis in vitro, with upregulation of proapoptotic proteins. In vivo, combination treatment suppressed tumor growth and significantly improved survival compared to either drug alone. RNA sequencing of tumor tissues revealed almost four thousand genes that were uniquely modulated by the combination, with several anti‐apoptotic genes significantly down‐regulated. Collectively, our data provide a rationale for combined BET and BRAF inhibition as a novel strategy for the treatment of melanoma.

Targeting Survival Pathways in Lymphoma

Targeting cellular death pathways including apoptosis is a promising strategy for cancer drug discovery. To date at least three major types of cell death have been distinguished, including: apoptosis, autophagy, and necrosis. Increasing evidence has begun to support a role of Bcl-2-family members in the cellular pathways involved in each of these processes. The induction of apoptosis in different types of tissue and in response to various stressors is a complex process that is controlled by different BCL-2 family members. Pharmacologic modulation of BCL-2 proteins and apoptosis can be achieved through different ways including the use of: (1) Modified peptides; (2) Small molecule inhibitors ofanti-apoptotic proteins; (3) Antisense strategies; and (4) TRAIL targeting. Non-peptide based small-molecule inhibitors of signaling pathways are at present the strategy of choice given their low antigenicity and generally more favorable pharmacokinetic and pharmacodynamic features, especially as they pertain to volume of distribution and intracellular accumulation. Bcl2-family inhibitors are showing impressive preclinical efficacy in animal models and are moving rapidly towards phase I and II clinical trials. Appropriate preclinical studies will need to identify the optimal strategies for combining these agents, with an emphasis on the importance of dose and schedule dependency.

New Drugs for the Treatment of Lymphoma

Historically, most drugs developed for treatment of leukemias, lymphomas, and myeloma had already been studied in the solid tumor setting. Nearly 10 years ago, chronic myelogenous leukemia (CML) forever changed this paradigm. Imatinib showed that it was possible to nullify the pathognomic genetic lesion in a hematologic malignancy. Since the approval of imatinib for CML, a host of new drugs active in blood cancers have emerged. This article highlights some areas of innovative drug development in lymphoma where possible; it emphasizes the biologic basis for the approach, linking this essential biology to the biochemical pharmacology. The article focuses on the many new targets including Syk, Bcl-2, CD-40, and the phosphoinositide-3 kinase/AKT/mammalian target of rapamycin pathway.

Development and Characterization of a Novel CD19CherryLuciferase (CD19CL) Transgenic Mouse for the Preclinical Study of B-Cell Lymphomas

Purpose: To generate a transgenic mouse that when crossed with spontaneous mouse models of lymphoma will allow for quantitative in vivo measurement of tumor burden over the entire spectrum of the disease and or response to therapy in a “disease” or lymphoma subtype-specific manner. Experimental Design: We developed a novel genetically engineered transgenic mouse using a CherryLuciferase fusion gene targeted to the CD19 locus to achieve B-cell–restricted fluorescent bioluminescent emission in transgenic mouse models of living mice. The use of a dual function protein enables one to link the in vivo analysis via bioluminescence imaging to cell discriminating ex vivo analyses via fluorescence emission. Results: The spatiotemporal tracking of B-cell lymphoma growth and the response of an established B-cell lymphoma to a drug known to induce remission was evaluated in a double transgenic animal obtained by crossing the CD19CherryLuciferase transgenic mouse to a mouse model of an aggressive B-cell lymphoma. The observations validated the use of the CD19CherryLuciferase transgenic mouse in the assessment of an active drug routinely used in the treatment of lymphoproliferative malignancies. Conclusions: The transgenic mouse described here is the first of its kind, intended to be used to hasten translational studies of novel agents in lymphoma, with the intent that understanding the relevant pharmacology before clinical study will accelerate successful development in clinical studies. Clin Cancer Res; 18(14); 3803–11. ©2012 AACR.

Diagnosis, Prognosis, and Treatment of Alveolar Soft-Part Sarcoma: A Review

Importance Alveolar soft-part sarcoma (ASPS) is a rare, translocation-driven sarcoma of the soft tissues. Alveolar soft-part sarcoma often affects young adults and is characterized by indolent behavior but early evidence of metastatic spread. After recognition of ASPS as a specific entity in 1952, retrospective data indicated prolonged survival in patients with metastases, despite inherent resistance to conventional doxorubicin-based chemotherapy. Tyrosine kinase inhibitors and immune checkpoint inhibitors have provided unexpected new treatment strategies for ASPS. Observations This review includes articles published between 1952 and March 1, 2018. With the introduction of new molecular diagnostic tools and therapies, the distinctive features of ASPS have become more evident. The identification and better understanding of molecular pathways activated by the characteristic t(X;17)(p11;q25) translocation and its correspondent chimeric ASPSCR1-transcription factor E3 (TFE3) fusion protein open new paths to drug development. The associations of TFE3 and facilitation of an immunosuppressive microenvironment provide a rationale for exploring treatments that affect the balance between T-effector cells and T-regulatory cells. Tyrosine kinase inhibitors, such as sunitinib, cediranib, and pazopanib, show activity with either tumor responses or disease stabilization in more than 50% of the cases. Given the association of new agents with patient outcomes, it is too early to say whether metastatic ASPS should still be considered incurable in all patients. Conclusions and Relevance The biologic outcomes of the canonical genomic event in ASPS remain under investigation; a better understanding of the tumor microenvironment and the multiple pathways activated in this sarcoma, including unusual bioenergetics, MET signaling, and angiogenesis, should lead to more rational therapy. Basket trials and related prospective studies focusing on the intersection of specific signaling pathways and diseases with unique genomic features, such as ASPS, will provide an understanding of new options for care.