Showing papers by "Peter H. Schafer published in 2007"
TL;DR: The results indicate that lenalidomide and CC-4047 have opposite effects in tumor cells versus normal cells and could explain, at least in part, the reduction of malignant cells and the restoration of bone marrow observed in patients undergoing lenalidumide treatment.
Abstract: Clinical studies involving patients with myelodysplastic syndromes or multiple myeloma have shown the efficacy of lenalidomide by reducing and often eliminating malignant cells while restoring the bone marrow function. To better understand these clinical observations, we investigated and compared the effects of lenalidomide and a structurally related analogue, CC-4047, on the proliferation of two different human hematopoietic cell models: the Namalwa cancer cell line and normal CD34+ progenitor cells. Both compounds had antiproliferative effects on Namalwa cells and pro-proliferative effects on CD34+ cells, whereas p21WAF-1 expression was up-regulated in both cell types. In Namalwa cells, the up-regulation of p21WAF-1 correlated well with the inhibition of cyclin-dependent kinase (CDK) 2, CDK4, and CDK6 activity leading to pRb hypophosphorylation and cell cycle arrest, whereas in CD34+ progenitor cells the increase of p21WAF-1 did not inhibit proliferation. Similarly, antiproliferation results were observed in two B lymphoma cell lines (LP-1 and U266) but interestingly not in normal B cells where a protection of apoptosis was found. Finally, CC-4047 and lenalidomide had synergistic effects with valproic acid [a histone deacetylase (HDAC) inhibitor] by increasing the apoptosis of Namalwa cells and enhancing CD34+ cell expansion. Our results indicate that lenalidomide and CC-4047 have opposite effects in tumor cells versus normal cells and could explain, at least in part, the reduction of malignant cells and the restoration of bone marrow observed in patients undergoing lenalidomide treatment. Moreover, this study provides new insights on the cellular pathways affected by lenalidomide and CC-4047, proposes new potential clinical uses, such as bone marrow regeneration, and suggests that the combination of lenalidomide or CC-4047 with certain HDAC inhibitors may elevate the therapeutic index in the treatment of hematologic malignancies.
233 citations
TL;DR: Lenalidomide and sorafenib are effective at targeting endothelial cells, inhibiting growth of ocular melanoma cells and can inhibit growth of tumors in a xenograft model as well as inhibit development of metastases.
Abstract: Background
Ocular melanoma is the leading intraocular malignancy. There is no effective treatment for metastatic ocular melanoma. We sought a treatment targeting the tumor microenvironment as well as the tumor cells.
40 citations
TL;DR: An in vitro ADCC system is utilized to assess the ability of these drugs to enhance human NK cell function in response to the approved therapeutic antibodies trastuzumab, cetuximab and rituximabs.
Abstract: 3023 Background: Potential mechanisms of action of lenalidomide and pomalidomide (CC-4047) include anti-angiogenic, anti- proliferative and immunomodulatory activities, e.g., enhancement of T cell and NK cell function. Both drugs appear to enhance T cell activation and Th1-type cytokines in cancer patients. Also, both drugs have been shown to enhance rituximab-mediated protection in a mouse lymphoma model. Methods: We have utilized an in vitro ADCC system to assess the ability of these drugs to enhance human NK cell function in response to the approved therapeutic antibodies trastuzumab, cetuximab and rituximab. Results: Pre-treatment of NK cells with either pomalidomide or lenalidomide greatly enhanced IFN-γ production by NK cells in response to IgG in the presence of either IL-2 or IL- 12. In a series of functional ADCC assays, Her2/neu overexpressing breast cancer cells (SKBR3 & MCF-7) pre-coated with trastuzumab, EGFR positive colorectal cancer cells (HCT-116) pre-coated with cetuximab and NHL cell li...
13 citations
Journal Article•
TL;DR: Investigation of the effect of lenalidomide on the formation of microvessels in a novel in vitro angiogenesis assay and in a capillary-like cord formation assay suggest that inhibitory effects on microvessel formation and inhibition of hypoxia-induced processes support a potential anti-angiogenic and anti-metastatic mechanism for this clinically active drug.
Abstract: A23 Lenalidomide (Revlimid®) is approved for the treatment of transfusion-dependent patients with anemia due to low- or intermediate-1-risk Myelodysplastic Syndromes (MDS) associated with a del 5q cytogenetic abnormality with or without additional cytogenetic abnormalities, and in combination with dexamethasone is for the treatment of multiple myeloma patients who have received at least one prior therapy. Previous reports suggest that lenalidomide is anti-angiogenic and this property appears to be related to efficacy in patients with MDS. We have investigated the effect of lenalidomide on the formation of microvessels in a novel in vitro angiogenesis assay utilizing human umbilical arterial rings and in a capillary-like cord formation assay using cultured primary endothelial cells. We found that lenalidomide consistently inhibits both sprout formation by arterial rings and cord formation by endothelial cells in a dose-dependent manner. We also found an inhibitory effect of lenalidomide on the associations between cadherin-5, β-catenin and CD31, adherens junction proteins whose interaction is critical for endothelial cell cord formation. Furthermore, lenalidomide inhibited VEGF-induced PI3K-Akt pathway signaling, which is known to regulate adherens junction formation. We also found a strong inhibitory effect of lenalidomide on hypoxia-induced endothelial cell formation of cords and HIF-1α expression, the main mediator of hypoxia-mediated effects and a key driver of angiogenesis and metastasis. Anti-metastatic activity of lenalidomide in vivo was confirmed in the B16-F10 mouse melanoma model by a >40% reduction in melanoma lung colony counts versus untreated mice. Our results suggest that inhibitory effects on microvessel formation, in particular adherens junction formation and inhibition of hypoxia-induced processes support a potential anti-angiogenic and anti-metastatic mechanism for this clinically active drug.
7 citations
TL;DR: The mechanism by which lenalidomide exerts its anti-proliferative effects in deletion 5q MDS clones or MM cells is not yet fully elucidated.
Abstract: 8110 Background: The mechanism by which lenalidomide exerts its anti-proliferative effects in deletion 5q MDS clones or MM cells is not yet fully elucidated. Early growth response (Egr1) gene is a ...
6 citations
TL;DR: In conclusion, lenalidomide demonstrates anti-proliferative activity against certain sensitive NHL cells, particularly in combination with dexamethasone.
5 citations
TL;DR: The ability of lenalidomide to enhance ADCC-mediated killing of rituximab treated CD20+ve NHL cell lines is mediated by granzyme B and FasL and is associated with clear effects on NK cell signaling and chemokine production.
5 citations
TL;DR: The results support the potential for a synergistic effect of lenalidomide in combination with dexamethasone in NHL and suggest these may be useful combinations, and partially additive effects of len Khalidomide with prednisone and etoposide suggest these might be useful combination.
1 citations