Ralf Kemmerling

Current Status of Therapeutic Targeting of Developmental Signalling Pathways in Oncology

Signalling pathways such as Hedgehog (Hh), Wnt, Notch, bone morphogenetic protein (BMP) and transforming growth factor-β (TGF-β) hold a central position in regulation of vertebrate development by controlling vital processes such as migration, differentiation and proliferation. Insights into the mechanistic aspects of cancer initiation and progression have pointed to striking similarities between tumourigenesis and embryonic development. These observations can partly be explained by the fact that similar cellular signalling mechanisms are employed in both situations. This review focuses on the role and therapeutic potential of Hh, Wnt, Notch and BMP/TGF-β signalling and discusses i) their signal transduction mechanisms during development and tumourigenesis, ii) evidence of pathway activation in different types of cancers, and, iii) strategies for pharmacological targeting. Numerous studies have demonstrated a crucial role of developmental signalling in a variety of tumours, where their signalling mechanisms contribute to oncogenic properties such as tumour cell proliferation, apoptosis inhibition and / or metastatic migration. From the literature available, it is obvious that the relative importance and the oncogenic mechanisms of developmental pathways vary with the tumour type, the stage of the disease as well as the interaction with the tumour microenvironment, thus highlighting the complexity of cellular signalling strategies employed during tumourigenesis. Intensive research activities are devoted to identification of drugs that interfere with oncogenic signalling by developmental pathways. First clinical data for such compounds--e.g. GDC-0449 for the Hh pathway--are promising and indicate that targeted therapy of developmental signalling pathways has potential for future anti-cancer therapies.

Comprehensive analysis of alterations in the miRNome in response to photodynamic treatment.

Photodynamic therapy (PDT) is a local tumour treatment accepted for a number of indications. PDT operates via the cellular stress response through the production of reactive oxygen species and subsequent cellular damage, resulting in cell death. Although PDT-induced signalling and cytotoxicity mechanisms have been investigated, the effect of PDT on microRNA (miRNA) expression is largely unknown. Therefore, we conducted a comprehensive microarray-based analysis of the miRNome of human epidermoid carcinoma cells (A431) following in vitro photodynamic treatment using polyvinylpyrrolidone hypericin (PVPH) as a photosensitiser and nearly homogeneous apoptosis-inducing conditions. Using microarray analysis we found eight miRNAs to be significantly differentially expressed 5h post treatment compared with the baseline levels and three miRNAs with more than 2-fold differential expression that could be detected in 1 or 2 biological replicates. The verification of these results by quantitative RT-PCR including a detailed time-course revealed an up to 15-fold transient over-expression of miR-634, miR-1246, miR-1290 and miR-487b compared with the basal level. For these miRNAs, in silico mRNA target prediction yielded numerous target transcripts involved in the regulation of cell stress, apoptosis, cell adherence and proliferation. This study provides the first comprehensive miRNome analysis after PDT treatment and may help to develop novel miRNA-based therapeutic approaches to further increase the efficiency of PDT.

Myelodysplastic Syndrome and Histone Deacetylase Inhibitors: “To Be or Not to Be Acetylated”?

Myelodysplastic syndrome (MDS) represents a heterogeneous group of diseases with clonal proliferation, bone marrow failure and increasing risk of transformation into an acute myeloid leukaemia. Structured guidelines are developed for selective therapy based on prognostic subgroups, age, and performance status. Although many driving forces of disease phenotype and biology are described, the complete and possibly interacting pathogenetic pathways still remain unclear. Epigenetic investigations of cancer and haematologic diseases like MDS give new insights into the pathogenesis of this complex disease. Modifications of DNA or histones via methylation or acetylation lead to gene silencing and altered physiology relevant for MDS. First clinical trials give evidence that patients with MDS could benefit from epigenetic treatment with, for example, DNA methyl transferase inhibitors (DNMTi) or histone deacetylase inhibitors (HDACi). Nevertheless, many issues of HDACi remain incompletely understood and pose clinical and translational challenges. In this paper, major aspects of MDS, MDS-associated epigenetics and the potential use of HDACi are discussed.

Robust linear regression model of Ki-67 for mitotic rate in gastrointestinal stromal tumors.

Risk stratification of gastrointestinal stromal tumors (GISTs) by tumor size, lymph node and metastasis status is crucially affected by mitotic activity. To date, no studies have quantitatively compared mitotic activity in hematoxylin and eosin (H&E)-stained tissue sections with immunohistochemical markers, such as phosphohistone H3 (PHH3) and Ki-67. According to the TNM guidelines, the mitotic count on H&E sections and immunohistochemical PHH3-stained slides has been assessed per 50 high-power fields of 154 specimens of clinically documented GIST cases. The Ki-67-associated proliferation rate was evaluated on three digitalized hot spots using image analysis. The H&E-based mitotic rate was found to correlate significantly better with Ki-67-assessed proliferation activity than with PHH3-assessed proliferation activity (r=0.780; P<0.01). A linear regression model (analysis of variance; P<0.001) allowed reliable predictions of the H&E-associated mitoses based on the Ki-67 expression alone. Additionally, the Ki-67-associated proliferation revealed a higher and significant impact on the recurrence and metastasis rate of the GIST cases than by the classical H&E-based mitotic rate. The results of the present study indicated that the mitotic rate may be reliably and time-efficiently estimated by immunohistochemistry of Ki-67 using only three hot spots.

Aspects of the differential diagnosis of clear-cell lesions of the skin in connection with the rare case of a clear-cell atypical fibroxanthoma

Clear-cell changes are rare in histological specimens of the dermis and raise complex diagnostic considerations regarding lineage differentiation (e.g., epithelial, mesenchymal, or melanocytic). We present a clear-cell atypical fibroxanthoma (CCAFX) and describe the morphological and immunohistochemical aspects of this rare skin lesion. Furthermore, we give an overview of the differential diagnoses of clear-cell lesions of the skin for a practical approach.

Invasive aspergillosis presenting with a painless complete ophthalmoplegia.

OBJECTIVE We report on a patient who presented with complete ophthalmoplegia as a first symptom of fatal invasive aspergillosis. CASE REPORT We present the clinical course of an immunocompromised 68-year-old man with unclear painless loss of vision, ptosis and ophthalmoplegia of the right eye lasting for 10 days which was referred from an ophthalmological outpatient clinic. He had a history of kidney transplantation after renal failure, diabetes mellitus II, and coronary heart disease. He was on immunosuppressive therapy with tacrolimus, mycophenolate and prednisolone since renal transplantation. The initial cranial magnetic resonance imaging (MRI) was unremarkable. The additional thin section computed tomography (CT) of the paranasal sinuses was suspicious for bone erosion of the superior wall of the right sphenoidal sinus. Initial laboratory testing and cerebrospinal fluid were without pathological findings. When the patient showed signs of generalised sepsis he was transferred to the intensive care unit. Due to fulminant sepsis it was not possible to perform the planned biopsy. The patient died a few days later of cardio-respiratory insufficiency. The consecutive autopsy revealed invasive aspergillosis of paranasal sinuses with infiltration into the orbita and intracranial spreading into sinus cavernous. Autopsy also showed aspergillus pneumonia. DISCUSSION Invasive aspergillosis of the paranasal sinuses and the skull base is most often a lethal condition in immunocompromised patients. Therefore, rapid diagnostics applying radiological (CT and MRI) and surgical procedures (biopsy) and immediate ignition of antimycotic treatment can be life-saving.

Differential diagnostic challenge of chronic neutrophilic leukemia in a patient with prolonged leukocytosis

Our interesting case deals with the clinical and morphological aspects of a chronic neutrophilic leukemia and the critical evaluation of differential diagnosis of leukemoid reaction in bone marrow biopsies.

Polymorphisms in genes involved in EGFR-turnover are predictive for cetuximab efficacy in colorectal cancer

Transmembrane receptors, such as the EGFR, are regulated by their turnover, which is dependent on the ubiquitin-proteasome system. We tested in two independent study cohorts whether SNPs in genes involved in EGFR turnover predict clinical outcome in cetuximab-treated metastatic colorectal cancer (mCRC) patients. The following SNPs involved in EGFR degradation were analyzed in a screening cohort of 108 patients treated with cetuximab in the chemorefractory setting: c-CBL (rs7105971; rs4938637; rs4938638; rs251837), EPS15 (rs17567; rs7308; rs1065754), NAE1 (rs363169; rs363170; rs363172), SH3KBP1 (rs7051590; rs5955820; rs1017874; rs11795873), SGIP1 (rs604737; rs6570808; rs7526812), UBE2M (rs895364; rs895374), and UBE2L3 (rs5754216). SNPs showing an association with response or survival were analyzed in BRAF and RAS wild-type samples from the FIRE-3 study. One hundred and fifty-three FOLFIRI plus cetuximab-treated patients served as validation set, and 168 patients of the FOLFIRI plus bevacizumab arm served as controls. EGFR FISH was done in 138 samples to test whether significant SNPs were associated with EGFR expression. UBE2M rs895374 was significantly associated with progression-free survival (log-rank P = 0.005; HR, 0.60) within cetuximab-treated patients. No association with bevacizumab-treated patients (n = 168) could be established (P = 0.56; HR, 0.90). rs895374 genotype did not affect EGFR FISH measurements. EGFR recycling is an interesting mechanism of secondary resistance to cetuximab in mCRC. This is the first report suggesting that germline polymorphisms in the degradation process predict efficacy of cetuximab in patients with mCRC. Genes involved in EGFR turnover may be new targets in the treatment of mCRC. Mol Cancer Ther; 14(10); 2374–81. ©2015 AACR.

Treatment of aggressive B-cell lymphoma in elderly patients: influence of single nucleotide polymorphisms affecting pharmacodynamics of chemotherapeutics

Abstract Clinical and/or biological risk factors are needed to identify elderly patients with aggressive B-cell lymphoma able to receive full-dose R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) treatment. We present a retrospective analysis of 83 patients ≥ 75 years of age (range: 75–97) who were diagnosed with aggressive B cell lymphoma between 2004 and 2011 in our clinic. R-CHOP-like therapy was administered in 82% of these patients resulting in a median overall survival of 54 months. A median cumulative dose of 226 mg/m2 doxorubicin and a median of six cycles were applied in these patients. Two genotypes of the CBR3 and MLH1 genes affecting the metabolism of cytostatics identified a subgroup with a favorable prognosis (median overall survival not reached vs. 30 months, p = 0.01). A treatment strategy aiming at full-dose R-CHOP was feasible and resulted in an encouraging treatment outcome in patients ≥ 75 years. Pharmacogenetic parameters, if independently validated, may be helpful in elderly patients.