Macrocyclization as a Source of Desired Polypharmacology. Discovery of Triple PI3K/mTOR/PIM Inhibitors.

The PI3K/AKT/mTOR and PIM kinase pathways contribute to the development of several hallmarks of cancer. Cotargeting of these pathways has exhibited promising synergistic therapeutic effects in liquid and solid tumor types. To identify molecules with combined activities, we cross-screened our collection of PI3K/(±mTOR) macrocycles (MCXs) and identified the MCX thieno[3,2-d]pyrimidine derivative 2 as a moderate dual PI3K/PIM-1 inhibitor. We report the medicinal chemistry exploration and biological characterization of a series of thieno[3,2-d]pyrimidine MCXs, which led to the discovery of IBL-302 (31), a potent, selective, and orally bioavailable triple PI3K/mTOR/PIM inhibitor. IBL-302, currently in late preclinical development (AUM302), has recently demonstrated efficacy in neuroblastoma and breast cancer xenografts. Additionally, during the course of our experiments, we observed that macrocyclization was essential to obtain the desired multitarget profile. As a matter of example, the open precursors 35-37 were inactive against PIM whereas MCX 28 displayed low nanomolar activity.

An open-label, multicenter, randomized phase Ib/II study of eribulin mesylate administered in combination with pemetrexed versus pemetrexed alone as second-line therapy in patients with advanced nonsquamous non-small-cell lung cancer.

INTRODUCTION: New treatment options are needed for second-line therapy in patients with NSCLC. PATIENTS AND METHODS: This was a phase Ib/II study in patients with nonsquamous NSCLC in whom 1 previous platinum-based chemotherapy regimen had failed. Fifteen patients were enrolled in a dose escalation of eribulin mesylate in combination with pemetrexed (E+P). In phase II (n = 80), E+P at the maximum tolerated dose was compared with P. RESULTS: In phase Ib, the maximum tolerated dose of E+P was defined as eribulin 0.9 mg/m(2) with pemetrexed (500 mg/m(2)) each on day 1 of a 21-day cycle. In phase II, adverse events were comparable between groups. PFS and OS were similar between treatment groups. Median PFS was 21.4 weeks for E+P (n = 26; 95% confidence interval [CI], 12.7-39.6) and 23.4 weeks for P (n = 29; 95% CI, 17.1-29.9), with a hazard ratio of 1.0 (95% CI, 0.6-1.7). CONCLUSION: During phase Ib, E+P was tolerated only at a markedly lower dosing intensity relative to the eribulin monotherapy regimen approved for breast cancer and used in phase II studies of NSCLC. At the selected phase II dosing regimen, E+P was generally safe and well tolerated but provided no therapeutic advantage for the second-line treatment of locally advanced or metastatic nonsquamous NSCLC.

Immunotherapy of human neuroblastoma using umbilical cord blood-derived effector cells.

Tumors of the nervous system, including neuroblastoma and glioblastoma, are difficult to treat with current therapies. Despite the advances in cancer therapeutics, the outcomes in these patients remain poor and, therefore, new modalities are required. Recent literature demonstrates that cytotoxic effector cells can effectively kill tumors of the nervous system. In addition, we have previously shown that umbilical cord blood (UCB) contains precursors of antitumor cytotoxic effector cells. Therefore, to evaluate the antitumor potential of UCB-derived effector cells, studies were designed to compare the in vitro and in vivo antitumor effects of UCB- and peripheral blood (PB)-derived antigen-nonspecific and antigen-specific effector cells against tumors of the nervous system. Mononuclear cells (MNCs) from UCB were used to generate both interleukin-2 (IL-2)-activated killer (LAK) cells and tumor-specific cytotoxic T lymphocytes (CTLs). UCB-derived LAK cells showed a significant in vitro cytotoxicity against IMR-32, SK-NMC, and U-87 human neuroblastoma and glioblastoma, respectively. In addition, the CTLs generated using dendritic cells primed with IMR-32 tumor cell lysate showed a selective cytotoxicity in vitro against IMR-32 cells, but not against U-87 or MDA-231 cells. Furthermore, treatment of SCID mice bearing IMR-32 neuroblastoma with tumor-specific CTLs resulted in a significant (p < 0.01) inhibition of tumor growth and increased overall survival. Thus, these results demonstrate the potential of UCB-derived effector cells against human neuroblastoma and warrant further preclinical studies.

Rituximab monotherapy for splenic marginal zone lymphoma.

In this retrospective study, rituximab was found to be effective therapy in 10 of 11 patients with splenic marginal zone lymphoma, inducing prompt reduction in splenomegaly, improvement in blood counts in 9 patients and clearance of a pleural effusion in 1 patient. Median response duration was 21 months (range 4 to 37 months). Two patients who relapsed at 21 and 23 months responded to retreatment. Rituximab should be considered in patients who are poor candidates for splenectomy.

Rituximab for treatment of refractory/relapsing thrombotic thrombocytopenic purpura (TTP).

Plasma exchange is the standard treatment for thrombotic thrombocytopenic purpura (TTP). For patients refractory to plasma exchange, treatment options are limited and often unsuccessful. The platelet thrombi that form in acquired TTP are believed to result from the presence of procoagulant ultralarge multimers of von Willebrand factor (VWF) in the circulation due to autoantibody inhibition of VWF cleaving protease (ADAMTS-13), the enzyme that normally cleaves the ultralarge multimers. Rituximab, a chimeric monoclonal antibody against CD20, has been recognized as a useful therapy for antibody-mediated autoimmune disease. We therefore treated four patients with recurrent TTP with 2 or 4 weekly doses of rituximab in addition to corticosteroids, vincristine, plasma, or continuing plasma exchange. Three patients responded with prompt improvement in microangiopathic hemolytic anemia and thrombocytopenia, which allowed plasma exchange to be discontinued or avoided and prednisone to be rapidly discontinued. Two of the 3 responders have remained in unmaintained complete remission for 13+ months. The third patient relapsed at 13 months; a second course of rituximab and prednisone resulted in an unmaintained remission for 6+ months. All four patients were tested for ADAMTS-13 activity and its inhibitor at a point in their course when samples were available. Low ADAMTS-13 activity was noted in 3 patients tested at relapse, and the inhibitor activity was detectable in 2 patients. ADAMTS-13 activity increased during remission in one of these 2 patients although the patient had a persistence of the inhibitor. One patient tested only during remission had a normal ADAMTS-13 level. We conclude that rituximab may have a role and deserves further study in the treatment of patients with relapsing TTP.

Comparison of phenotypic and functional dendritic cells derived from human umbilical cord blood and peripheral blood mononuclear cells.

Dendritic cells (DC) are important accessory cells that are capable of initiating an immune response. Generation of functional DC has potential clinical use in treating diseases such as cancer. In this report, we have demonstrated the generation of functional DC from mononuclear cells isolated from human umbilical cord blood cells (UCBC) and peripheral blood cells (PBC) using a defined medium Prime Complete Growth Medium (PCGM) (GenePrime LLC, Gaithersburg, MD). DC generated using PCGM showed the typical phenotype of DC as determined by flow cytometry and electron microscopy. Further analysis of the DC using confocal microscopy showed localization of the antigen and major histocompatibility complex (MHC) molecules in the cytoplasm 3-5 days following tumor antigen loading into DC. Subsequently, the tumor antigen-MHC complex was localized on the surface of DC. DC generated from UCBC or PBC also increased (p < 0.001) the allogeneic mixed lymphocyte reaction, confirming their immune accessory functions compared to a control mixed lymphocyte reaction (MLR) without DC added. Interestingly, DC generated using PCGM medium also significantly enhanced the hematopoietic colony (CFU-C)-forming ability. Furthermore, addition of 5% DC derived from cord blood loaded with tumor antigen also significantly (p < 0.001) increased peripheral and cord blood-derived antigen-specific cytotoxic T lymphocyte (CTL)-mediated killing of human leukemic cells (K562) and breast cancer cells (MDA-231). Thus, these results show that functional DC generated from cord blood using a defined medium are a useful source of accessory cells for augmenting CTL-mediated cytotoxicity and have potential use in cellular therapy for human leukemia and breast cancer.