The phosphatidylinositol 3-kinase signal transduction pathway members are often activated in tumor samples from patients with non-Hodgkin's lymphoma (NHL). Everolimus is an oral agent that targets the raptor mammalian target of rapamycin (mTORC1). The goal of this trial was to learn the antitumor activity and toxicity of single-agent everolimus in patients with relapsed/refractory aggressive NHL. Patients received everolimus 10 mg PO daily. Response was assessed after two and six cycles, and then every three cycles until progression. A total of 77 patients with a median age of 70 years were enrolled. Patients had received a median of three previous therapies and 32% had undergone previous transplant. The overall response rate (ORR) was 30% (95% confidence interval: 20–41%), with 20 patients achieving a partial remission and 3 a complete remission unconfirmed. The ORR in diffuse large B cell was 30% (14/47), 32% (6/19) in mantle cell and 38% (3/8) in follicular grade 3. The median duration of response was 5.7 months. Grade 3 or 4 anemia, neutropenia and thrombocytopenia occurred in 14, 18 and 38% of patients, respectively. Everolimus has single-agent activity in relapsed/refractory aggressive NHL and provides proof-of-concept that targeting the mTOR pathway is clinically relevant.

PD-L1 expression in primary clear cell renal cell carcinoma (ccRCC) increases the likelihood of response to anti-PD-1 inhibition, but fails to identify all responders. We hypothesized that PD-L1 levels assessed in randomly selected areas of the primary tumors may not accurately reflect expression levels in metastatic lesions, which are the target of systemic therapy. Therefore, we compared PD-L1 expression in a series of primary ccRCC and their metastases. Tissue blocks from 53 primary ccRCCs and 76 corresponding metastases were retrieved. Areas with predominant and highest nuclear grade were selected. Slides were immunostained with a validated anti-PD-L1 antibody (405.9A11). Membranous expression in tumor cells was quantified using H-score. Expression in tumor-infiltrating mononuclear cells (TIMC) was quantified using a combined score. Discordant tumor cell PD-L1 staining between primary tumors and metastases was observed in 11/53 cases (20.8%). Overall, tumor cell PD-L1 levels were not different in primary tumors and metastases (p=0.51). Tumor cell PD-L1 positivity was associated with higher T stage (p=0.03) and higher Fuhrman Nuclear Grade (FNG) (p<0.01). Within individual lesions, PD-L1 positivity was heterogeneous and almost exclusively detected in high nuclear grade areas (p<0.001). No difference was found in PD-L1 levels in TIMCs between primary tumors and metastases (p=0.82). Heterogeneity of PD-L1 expression in ccRCC suggests that its assessment as predictive biomarker for PD-1 blockade may require analysis of metastatic lesions. Notably, since PD-L1 expression was mostly detected in high nuclear grade areas, to avoid false negative results, these areas should be specifically selected for assessment.

The mammalian target of rapamycin (mTOR) has emerged as an important therapeutic target for diffuse large B-cell lymphoma (DLBCL), as recent studies have demonstrated that 30% of relapsed patients respond to mTOR inhibitors. Why some lymphomas are resistant is incompletely understood. In the present study, we demonstrated that rapamycin inhibits mTORC1 in DLBCL lines and primary tumors but is minimally cytotoxic. Subsequent investigations revealed that rapamycin also activated eIF4E and the mTORC2 target Akt, suggesting a potential mechanism of rapamycin resistance. IntroductionDiffuse large B-cell lymphoma (DLBCL), an aggressive form of non-Hodgkin lymphoma (NHL), is the most common type of lymphoma in the United States. With rituximab-based chemoimmunotherapy such as rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone, approximately 60% of DLBCL patients are cured. 1,2 Salvage chemotherapy followed by stem cell transplantation is able to produce durable remissions in a minority of relapsed patients, and improved therapy is required for those who relapse after second-line treatment.Because deregulation of the PI3 kinase (PI3K)/mTOR pathway occurs in many human diseases, 3,4 targeting the mTOR pathway with small molecule inhibitors has become an intense area of research. Key components of this pathway, including Akt and mTOR, regulate cell growth and survival. 5 The mTOR kinase exists as 2 complexes. The rapamycin-sensitive mTOR complex 1 (mTORC1 or raptor/mTOR), consists of mTOR, raptor, and mLST8. mTORC1 regulates translation initiation through 2 distinct pathways: ribosomal p70 S6 kinase (p70S6K) and eukaryotic translation initiation factor 4E (eIF4E) binding proteins (4E-BPs). In one pathway, mTORC1 phosphorylates and activates the ribosomal protein S6. In the second pathway, mTORC1 directly phosphorylates 4E-BP1 causing its dissociation from the translation initiation factor eIF4E. This allows eIF4E to stimulate cap-dependent RNA translation. In the absence of mTORC1 activation, 4EBP1 binds tightly to eIF4E, preventing it from binding to 5Ј-capped mRNA. 6 The mTOR complex 2 (mTORC2 or rictor/mTOR), which contains mTOR, rictor, and mLST8, is rapamycin insensitive and functions to regulate the survival kinase Akt by phosphorylation of serine 473. 5 Recent clinical trials of the mTORC1 inhibitors temsirolimus and everolimus, both analogues of the parent compound rapamycin, have demonstrated overall response rates (ORRs) of approximately 30% for relapsed DLBCL. 7 This single-agent activity of mTOR inhibitors in heavily pretreated DLBCL patients highlights the importance of the PI3K/mTOR pathway in these cells. To exploit the sensitivity of lymphomas to mTOR inhibitors through effective therapies, it is important to understand the mechanistic basis for resistance of DLBCL to mTOR inhibition.Histone deacetylase inhibitors (HDIs) have emerged as a potentially promising new class of anticancer drugs. The inhibition of histone deacetylases (HDACs) by HDIs results in increased gene-specific his...

Chronic myelogenous leukemia (CML) results from malignant transformation of a primitive hematopoietic cell by the BCR/ ABL oncogene. The breakpoint cluster region/ABL (BCR/ABL) tyrosine kinase inhibitor imatinib mesylate (imatinib) is highly effective in inducing remissions in CML. However, the effects of imatinib on intracellular signaling in primary progenitor cells are not well described. We show that imatinib exposure resulted in a significant dose-responsive reduction in BCR/ ABL kinase activity in CML CD34 ؉ cells. However, imatinib treatment resulted in an increase in activity of p42/44 mitogenactivated protein kinase (MAPK), an important downstream effector of BCR/ ABL. Increased MAPK activity was growth factor dependent. Pharmacologic inhibition of MAPK using MAPK/extracellular signal-regulated kinase kinase-1/2 (MEK-1/2) inhibitors significantly reduced CML progenitor proliferation. Combined treatment with a MEK-1/2 inhibitor and imatinib significantly increased suppression of CML progenitors compared with either inhibitor alone. In contrast, imatinib treatment resulted in a small reduction in AKT activity. Combined treatment with a phosphatidylinositol-3 (PI-3) kinase inhibitor and imatinib significantly increased suppression of CML progenitor growth compared with either inhibitor alone. We conclude that inhibition of BCR/ABL kinase activity in CML progenitors by imatinib results in a growth factor-dependent compensatory increase in MAPK activity and in only partial inhibition of PI-3 kinase activity. These mechanisms may contribute to incomplete elimination of CML progenitors by imatinib. ( IntroductionChronic myelogenous leukemia (CML) is a clonal hematopoietic disorder resulting from malignant transformation of a primitive hematopoietic cell. 1 Stem cell transformation in CML results in abnormal proliferation and expansion of malignant progenitors, precursors, and mature hematopoietic cells. 1,2 Clinically, CML inevitably progresses from an initial chronic phase (CP) through an accelerated phase (AP) and a terminal blast crisis (BC) or an acute leukemic phase. Malignant cells in CML have a characteristic karyotypic abnormality, the translocation t(9;22). 3 At the molecular level, this translocation results in the formation of an abnormal BCR/ABL fusion gene. 4 Several studies indicate that the BCR/ABL gene is required and sufficient for development of CML. [5][6][7] The fusion of N-terminal breakpoint cluster region (BCR) sequences to the ABL tyrosine kinase (TK) results in constitutive activation and enhancement of the TK activity of the BCR/ABL protein (p210 BCR/ABL ). 8 Abnormal TK activity is critical for the transforming ability of p210 BCR/ABL . 9 Deregulated TK activity results in activation of several downstream signaling pathways, including the Ras/mitogen-activated protein kinase (Ras/MAPK), phosphatidylinositol-3 kinase/AKT (PI-3K/AKT), and signal transducer and activator of transcription (STAT) pathways, which are implicated in mitogenic signaling and enhancement of survival. 1,10 Imat...

Summary It has been reported that the diagnosis of serous tubal intraepithelial carcinoma (STIC) is not optimally reproducible based only on histologic assessment. Recently, we reported that the use of a diagnostic algorithm that combines histologic features and coordinate immunohistochemical expression of p53 and Ki-67 substantially improves reproducibility of the diagnosis. The goal of the current study was to validate this algorithm by testing a group of 6 gynecologic pathologists who had not participated in the development of the algorithm (3 faculty, 3 fellows) but who were trained in its use by referring to a website designed for that purpose. They then reviewed a set of microscopic slides, which contained 41 mucosal lesions of the fallopian tube. Overall consensus (≥4 of 6 pathologists) for the 4 categories of STIC, serous tubal intraepithelial lesion (our atypical intermediate category), p53 signature, and normal/reactive was achieved in 76% of lesions with no consensus in 24%. Combining diagnoses into 2 categories (STIC vs. non-STIC) resulted in overall consensus in 93% with no consensus in 7%. The kappa value for STIC vs. non-STIC among all 6 observers was also high at 0.67 and did not significantly differ whether for faculty (κ=0.66) or fellows (κ=0.60). These findings confirm the reproducibility of this algorithm by a group of gynecologic pathologists who were trained on a website for that purpose. Accordingly, we recommend its use in research studies. Before applying it in routine clinical practice, the algorithm should be evaluated by general surgical pathologists in the community setting.

Cytokines are deregulated in cancers and can contribute to tumor growth. In patients with diffuse large-cell lymphoma (DLBCL), we observed higher levels of JAK/STAT pathway-related serum cytokines (ie, IL-6, IL-10, epidermal growth factor, and IL-2) compared with controls. Of these, only IL-10 activated the JAK2 pathway in lymphoma cells in vitro. Patients with high serum IL-10 had shorter event-free survival (EFS) than patients with low levels (P > .01) and high IL-10 was correlated with high lactase dehydrogenase (P = .0085) and higher International Prognostic Index scores (P = .01). To explore the mechanism by which IL-10 may contribute to an inferior EFS, we investigated the effect of IL-10 on the JAK2 pathway and found that the IL-10/IL-10 receptor complex up-regulated JAK2 signaling. Neutralizing Ab to IL-10 inhibited constitutive and IL-10-induced JAK2/STAT3 phosphorylation. JAK2 inhibition dephosphorylated JAK2 and STAT3 and caused an inhibitory effect on phospho-JAK2-positive DLBCL cells; there was a minimal effect on phospho-JAK2-negative cells. Apoptosis induced by JAK2 inhibition was dependent on inhibition of autocrine IL-10 and c-myc expression and independent of Bcl-2 family expression. These results provide the rationale for testing JAK2 inhibitors in DLBCL patients, and indicate that serum IL-10 may be a biomarker to identify patients more likely to respond to JAK2-targeted therapy.

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Diffuse large B-cell lymphoma (DLBCL) with an activated B-cell (ABC) gene-expression profile has been shown to have a poorer prognosis compared with tumors with a germinal center B-cell type. ABC cell lines have constitutive activation of STAT3; however, the mechanisms regulating STAT3 signaling in lymphoma are unknown. In studies of class-I histone deacetylase (HDAC) expression, we found overexpression of HDAC3 in phospho STAT3-positive DLBCL and the HDAC3 was found to be complexed with STAT3. Inhibition of HDAC activity by panobinostat (LBH589) increased p300-mediated STAT3Lys685 acetylation with increased nuclear export of STAT3 to the cytoplasm. HDAC inhibition abolished STAT3Tyr705 phosphorylation with minimal effect on STAT3Ser727 and JAK2 tyrosine activity. pSTAT3Tyr705-positive DLBCLs were more sensitive to HDAC inhibition with LBH589 compared with pSTAT3Tyr705-negative DLBCLs. This cytotoxicity was associated with downregulation of the direct STAT3 target Mcl-1. HDAC3 knockdown upregulated STAT3Lys685 acetylation but prevented STAT3Tyr705 phosphorylation and inhibited survival of pSTAT3-positive DLBCL cells. These studies provide the rationale for targeting STAT3-positive DLBCL tumors with HDAC inhibitors.