Faculty Bibliography

Primary myelofibrosis (PMF) is characterized by fibrosis, ineffective hematopoiesis in marrow, and hematopoiesis in extramedullary sites and is associated with abnormal megakaryocyte (MK) development and increased transforming growth factor (TGF)-beta1 release. To clarify the role of TGF-beta1 in the pathogenesis of this disease, the TGF-beta1 signaling pathway of marrow and spleen of the Gata1(low) mouse model of myelofibrosis (MF) was profiled and the consequences of inhibition of TGF-beta1 signaling on disease manifestations determined. The expression of 20 genes in marrow and 36 genes in spleen of Gata1(low) mice was altered. David-pathway analyses identified alterations of TGF-beta1, Hedgehog, and p53 signaling in marrow and spleen and of mammalian target of rapamycin (mTOR) in spleen only and predicted that these alterations would induce consequences consistent with the Gata1(low) phenotype (increased apoptosis and G1 arrest both in marrow and spleen and increased osteoblast differentiation and reduced ubiquitin-mediated proteolysis in marrow only). Inhibition of TGF-beta1 signaling normalized the expression of p53-related genes, restoring hematopoiesis and MK development and reducing fibrosis, neovascularization, and osteogenesis in marrow. It also normalized p53/mTOR/Hedgehog-related genes in spleen, reducing extramedullary hematopoiesis. These data identify altered expression signatures of TGF-beta1 signaling that may be responsible for MF in Gata1(low) mice and may represent additional targets for therapeutic intervention in PMF.

Panobinostat (LBH589), a novel histone deacetylase inhibitor (HDACi), was evaluated in a phase I study of patients with primary myelofibrosis (PMF) and post-essential thrombocythaemia/polycythaemia vera-related myelofibrosis (Post-ET/PV MF). Eighteen patients (PMF 56%; Post-PV MF 28%; Post-ET MF 17%) were treated in three cohorts at oral doses of (i) 20, (ii) 30, and (iii) 25 mg three times weekly consecutively. Reversible thrombocytopenia was the dose-limiting toxicity. Five patients (two in Dose Cohort 1, one in Dose Cohort 2 and two in Dose Cohort 3) received six or more cycles and were evaluable for response assessment. After the sixth cycle, three of these five patients achieved clinical improvement (CI) with 100% reduction in palpable splenomegaly from baseline, and two patients experienced stable disease. Panobinostat therapy was also associated with improvement in the degree of anaemia in two of the five patients. Of the three patients who achieved CI after six cycles, one patient achieved a near complete remission after 15 cycles of treatment and another patient had resolution of marrow fibrosis after 16 cycles. We conclude that panobinostat is a well-tolerated, clinically active treatment for MF patients, regardless of JAK2 V617F status, and most effective when given at low doses over long periods of time.

9 Background: Traditionally, breast cancer-related lymphedema is considered to be mainly due to the mechanical injury from cancer surgery. Recent research identified that inflammation-infection may be one of the important predictors for lymphedema. This pilot study aimed to explore the associations between lymphatic and pro-inflammatory candidate gene variations and lymphedema. METHODS: A prospective, longitudinal, repeated-measure, and comparative design was used to recruit 178 breast cancer survivors. To ensure the accuracy of lymphedema phenotype, lymphedema was classified into lymphedema of arm and breast. Arm lymphedema must have been validated by infra-red perometer and a bioimpedance device. Breast lymphedema was validated by an observational scale since no objective measure is available. Saliva samples were collected for DNA extraction. Candidate Gene Association Research Method was used to examine the eight genes known for inflammation and lymphatic specific growth factors: cytokines (IL1A, IL6, IL8, IL10, IL13) and PTGS2 (COX2), and lymphatic specific growth factors [VEGF-C and D]. Descriptive statistics, Chi-Squared tests for contingency tables and one-way analysis of variance for continuous variables were used to compare the genotypes for each of these genes in patients with and without lymphedema. Odds ratios of developing lymphedema are estimated. RESULTS: Among 178 survivors, 39 women were confirmed to have arm lymphedema and 43 women had breast lymphedema. Five genes were significantly associated with breast cancer-related lymphedema. Specific single nucleic polymorphisms (SNPs) for lymphatic specific growth factors VEGF-C (rs4604006) and cytokine IL13 (rs1800925) were related to arm lymphedema. Specific SNPs of cytokine IL1A (rs1800587) and PTGS2 (COX2) (rs20417) were associated with breast lymphedema. CONCLUSIONS: Our findings provided preliminary data on genetic susceptibility as a risk factor for breast cancer-related lymphedema. Findings of our study may serve as a preliminary foundation for a priori recognition of genetic risk that may facilitate lymphedema risk prediction prior to surgery and raises the potential for early intervention for a high-risk group.

PURPOSE: Skin metastases of breast cancer remain a therapeutic challenge. Toll-like receptor 7 agonist imiquimod is an immune response modifier and can induce immune-mediated rejection of primary skin malignancies when topically applied. Here we tested the hypothesis that topical imiquimod stimulates local antitumor immunity and induces the regression of breast cancer skin metastases. EXPERIMENTAL DESIGN: A prospective clinical trial was designed to evaluate the local tumor response rate of breast cancer skin metastases treated with topical imiquimod, applied 5 d/wk for 8 weeks. Safety and immunologic correlates were secondary objectives. RESULTS: Ten patients were enrolled and completed the study. Imiquimod treatment was well tolerated, with only grade 1 to 2 transient local and systemic side effects consistent with imiquimod's immunomodulatory effects. Two patients achieved a partial response [20%; 95% confidence interval (CI), 3%-56%]. Responders showed histologic tumor regression with evidence of an immune-mediated response, showed by changes in the tumor lymphocytic infiltrate and locally produced cytokines. CONCLUSION: Topical imiquimod is a beneficial treatment modality for breast cancer metastatic to skin/chest wall and is well tolerated. Importantly, imiquimod can promote a proimmunogenic tumor microenvironment in breast cancer. Preclinical data generated by our group suggest superior results with a combination of imiquimod and ionizing radiation and we are currently testing in patients whether the combination can further improve antitumor immune and clinical responses.