Patrick A Oberholzer

Inselspital, Universitätsspital Bern, Berna, Bern, Switzerland

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Publications (23)114.56 Total impact

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    ABSTRACT: Solid organ transplant recipients (SOTRs) have an increased risk of skin cancer due to their long-term immunosuppressed state. These patients should benefit from pre- and post-transplant screening and management of skin cancer by a dermatologist. The frequency of the dermatological consultations mainly depends on the previous history of skin cancer and this will be discussed in detail. In addition to cancer screening and management, dermatological consultations serve to educate and enforce patients' sun-protective behavior. Indeed, SOTRs are very sensitive to sun damage due to their immunosuppressed state, leading to cumulative sun damage and numerous in situ epithelial lesions termed 'field cancerization', which are large areas with increased carcinogenesis. Lesions should be recognized and treated as early as possible using therapeutic options ranging from topical therapy and surgical management to the adjustment of the patient's immunosuppressive therapy and chemoprevention. Therefore, dermatological follow-up of SOTRs is an essential component of the management of these patients and needs to be integrated into the comprehensive post-transplant care.
    No preview · Article · Jun 2012 · Expert Review of Dermatology
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    ABSTRACT: Solid organ transplant recipients (SOTR) have an increased risk of skin cancer due to their long-term immunosuppressive state. As the number of these patients is increasing, as well as their life expectancy, it is important to discuss the screening and management of skin cancer in this group of patients. The role of the dermatologist, in collaboration with the transplant team, is important both before transplantation, where patients are screened for skin lesions and the individual risk for skin cancer development is assessed, and after transplantation. Posttransplant management consists of regular dermatological consultations (the frequency depends on different factors discussed below), where early skin cancer screening and management, as well as patient education on sun protective behavior is taught and enforced. Indeed, SOTR are very sensitive to sun damage due to their immunosuppressive state, leading to cumulative sun damage which results in field cancerization with numerous lesions such as in situ squamous cell carcinoma, actinic keratosis and Bowen's disease. These lesions should be recognized and treated as early as possible. Therapeutic options discussed will involve topical therapy, surgical management, adjustment of the patient's immunosuppressive therapy (i.e. reduction of immunosuppression and/or switch to mammalian target of rapamycin inhibitors) and chemoprevention with the retinoid acitretin, which reduces the recurrence rate of squamous cell carcinoma. The dermatological follow-up of SOTR should be integrated into the comprehensive posttransplant care.
    No preview · Article · Feb 2012 · Current problems in dermatology
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    ABSTRACT: RAF inhibitors are effective against melanomas with BRAF V600E mutations but may induce keratoacanthomas (KAs) and cutaneous squamous cell carcinomas (cSCCs). The potential of these agents to promote secondary malignancies is concerning. We analyzed cSCC and KA lesions for genetic mutations in an attempt to identify an underlying mechanism for their formation. Four international centers contributed 237 KA or cSCC tumor samples from patients receiving an RAF inhibitor (either vemurafenib or sorafenib; n = 19) or immunosuppression therapy (n = 53) or tumors that developed spontaneously (n = 165). Each sample was profiled for 396 known somatic mutations across 33 cancer-related genes by using a mass spectrometric-based genotyping platform. Mutations were detected in 16% of tumors (38 of 237), with five tumors harboring two mutations. Mutations in TP53, CDKN2A, HRAS, KRAS, and PIK3CA were previously described in squamous cell tumors. Mutations in MYC, FGFR3, and VHL were identified for the first time. A higher frequency of activating RAS mutations was found in tumors from patients treated with an RAF inhibitor versus populations treated with a non-RAF inhibitor (21.1% v 3.2%; P < .01), although overall mutation rates between treatment groups were similar (RAF inhibitor, 21.1%; immunosuppression, 18.9%; and spontaneous, 17.6%; P = not significant). Tumor histology (KA v cSCC), tumor site (head and neck v other), patient age (≤ 70 v > 70 years), and sex had no significant impact on mutation rate or type. Squamous cell tumors from patients treated with an RAF inhibitor have a distinct mutational profile that supports a mechanism of therapy-induced tumorigenesis in RAS-primed cells. Conceivably, cotargeting of MEK together with RAF may reduce or prevent formation of these tumors.
    Full-text · Article · Nov 2011 · Journal of Clinical Oncology
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    ABSTRACT: Cutaneous T-cell lymphoma (CTCL) is a heterogeneous non-Hodgkin's lymphoma that may variably involve the skin, lymph nodes, and peripheral blood. Malignant burden ranges from cutaneous patches and plaques with little evidence of blood involvement to erythroderma often in association with frank leukemia, as in Sézary syndrome. Toward a better understanding of the pathogenesis of this CD4+ T-cell malignancy, we conducted a high-resolution genomic analysis combining DNA (23 samples) and mRNA (12 samples) data of peripheral blood isolates from CTCL patients across a spectrum of stages. Strikingly, even patients with limited involvement, e.g., normal CD4 counts, contained significant copy-number alterations. Defining genomic characteristics of CTCL blood involvement included gains on 8q and 17q, and deletions on 17p and chromosome 10. A consensus analysis of 108 leukemic CTCL samples demonstrated global similarities among patients with varied blood involvement, narrowing 38 of 62 loci. Toward an annotated framework for in vitro testing, we also characterized genomic alterations in five CTCL cell lines (HH, HUT78, PNO, SeAx, and Sez4), revealing intact core features of leukemic CTCL. Together, these studies produce the most comprehensive view of the leukemic CTCL genome to date, with implications for pathogenesis, molecular classification, and potential future therapeutic developments.
    Full-text · Article · Sep 2011 · Journal of Investigative Dermatology
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    ABSTRACT: Cutaneous T-cell lymphomas (CTCLs) are malignancies of skin-homing lymphoid cells, which have so far not been investigated thoroughly for common oncogenic mutations. We screened 90 biopsy specimens from CTCL patients (41 mycosis fungoides, 36 Sézary syndrome, and 13 non-mycosis fungoides/Sézary syndrome CTCL) for somatic mutations using OncoMap technology. We detected oncogenic mutations for the RAS pathway in 4 of 90 samples. One mycosis fungoides and one pleomorphic CTCL harbored a KRAS(G13D) mutation; one Sézary syndrome and one CD30(+) CTCL harbored a NRAS(Q61K) amino acid change. All mutations were found in stage IV patients (4 of 42) who showed significantly decreased overall survival compared with stage IV patients without mutations (P = .04). In addition, we detected a NRAS(Q61K) mutation in the CTCL cell line Hut78. Knockdown of NRAS by siRNA induced apoptosis in mutant Hut78 cells but not in CTCL cell lines lacking RAS mutations. The NRAS(Q61K) mutation sensitized Hut78 cells toward growth inhibition by the MEK inhibitors U0126, AZD6244, and PD0325901. Furthermore, we found that MEK inhibitors exclusively induce apoptosis in Hut78 cells. Taken together, we conclude that RAS mutations are rare events at a late stage of CTCL, and our preclinical results suggest that such late-stage patients profit from MEK inhibitors.
    Full-text · Article · Feb 2011 · Blood
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    ABSTRACT: Cutaneous T-cell lymphomas (CTCLs) are malignancies of skin-homing lymphoid cells, which have so far not been investigated thoroughly for common oncogenic mutations. We screened 90 biopsy specimens from CTCL patients (41 mycosis fungoides, 36 Sézary syndrome, and 13 non-mycosis fungoides/Sézary syndrome CTCL) for somatic mutations using OncoMap technology. We detected oncogenic mutations for the RAS pathway in 4 of 90 samples. One mycosis fungoides and one pleomorphic CTCL harbored a KRAS(G13D) mutation; one Sézary syndrome and one CD30(+) CTCL harbored a NRAS(Q61K) amino acid change. All mutations were found in stage IV patients (4 of 42) who showed significantly decreased overall survival compared with stage IV patients without mutations (P = .04). In addition, we detected a NRAS(Q61K) mutation in the CTCL cell line Hut78. Knockdown of NRAS by siRNA induced apoptosis in mutant Hut78 cells but not in CTCL cell lines lacking RAS mutations. The NRAS(Q61K) mutation sensitized Hut78 cells toward growth inhibition by the MEK inhibitors U0126, AZD6244, and PD0325901. Furthermore, we found that MEK inhibitors exclusively induce apoptosis in Hut78 cells. Taken together, we conclude that RAS mutations are rare events at a late stage of CTCL, and our preclinical results suggest that such late-stage patients profit from MEK inhibitors.
    Full-text · Article · Jan 2011
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    Marie C Zipser · Joanna Mangana · Patrick A Oberholzer · Lars E French · Reinhard Dummer
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    ABSTRACT: The use of laser therapy in the treatment of pigmented lesions is a controversial issue as it can delay melanoma diagnosis and may negatively impact mortality. Few cases of melanoma after laser therapy have been reported. It is still unknown whether melanoma can be induced by lasers. We discuss the outcomes of twelve patients presenting with melanoma subsequent to previous treatment with laser. In four patients, a skin biopsy was performed before laser treatment. Histology was re-evaluated by a panel of experienced dermatopathologists and analyzed in the context of clinical and photo-optical data. There was evidence for pathological misdiagnosis in two cases. The other two cases initially presented with non-suspicious features before laser treatment and were clearly diagnosed as melanoma thereafter, opening the possibility of melanoma induction by laser treatment. Most patients were female and presented with facial lesions. Three patients have already died of melanoma and two are in stage IV, showing progressive disease with distant metastases. Laser therapy is a common treatment for pigmented lesions, increasing the risk of delayed melanoma diagnosis. This prevents appropriate and timely therapy, and may therefore lead to a fatal outcome. A careful examination of all pigmented lesions using surface microscopy and representative biopsies in combination with a close follow-up is recommended.
    Full-text · Article · May 2010 · European journal of dermatology: EJD
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    ABSTRACT: Genetic alterations that activate the mitogen-activated protein kinase (MAP kinase) pathway occur commonly in cancer. For example, the majority of melanomas harbor mutations in the BRAF oncogene, which are predicted to confer enhanced sensitivity to pharmacologic MAP kinase inhibition (e.g., RAF or MEK inhibitors). We investigated the clinical relevance of MEK dependency in melanoma by massively parallel sequencing of resistant clones generated from a MEK1 random mutagenesis screen in vitro, as well as tumors obtained from relapsed patients following treatment with AZD6244, an allosteric MEK inhibitor. Most mutations conferring resistance to MEK inhibition in vitro populated the allosteric drug binding pocket or alpha-helix C and showed robust ( approximately 100-fold) resistance to allosteric MEK inhibition. Other mutations affected MEK1 codons located within or abutting the N-terminal negative regulatory helix (helix A), which also undergo gain-of-function germline mutations in cardio-facio-cutaneous (CFC) syndrome. One such mutation, MEK1(P124L), was identified in a resistant metastatic focus that emerged in a melanoma patient treated with AZD6244. Both MEK1(P124L) and MEK1(Q56P), which disrupts helix A, conferred cross-resistance to PLX4720, a selective B-RAF inhibitor. However, exposing BRAF-mutant melanoma cells to AZD6244 and PLX4720 in combination prevented emergence of resistant clones. These results affirm the importance of MEK dependency in BRAF-mutant melanoma and suggest novel mechanisms of resistance to MEK and B-RAF inhibitors that may have important clinical implications.
    Full-text · Article · Nov 2009 · Proceedings of the National Academy of Sciences

  • No preview · Article · Sep 2009 · Journal of Investigative Dermatology

  • No preview · Conference Paper · Aug 2009
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    Full-text · Article · Aug 2009 · Dermatology
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    ABSTRACT: Granulomatous slack skin (GSS) is an extremely rare disorder within the group of cutaneous T cell lymphomas (CTCL). Ultraviolet A1 (UVA1) phototherapy has previously been reported to be useful in the treatment of CTCL such as mycosis fungoides. We report a 35-year-old Caucasian male with GSS treated with UVA1 phototherapy starting at 20 J/cm(2) UVA1 3 times a week and subsequently increased in increments of 5 J/cm(2) to a medium-range dose of 50 J/cm(2) per session. The patient underwent a total of 45 sessions with a cumulative dose of 1,495 J/cm(2) UVA1 without any adverse events. At the conclusion of UVA1 phototherapy, a decrease in erythema and skin thickness was observed which was most prominent in the periphery of the lesion in the right groin area. A follow-up 12 months after phototherapy showed continued treatment benefit. To our knowledge, this is the first report describing the successful use of UVA1 (340-400 nm) phototherapy in a patient with GSS.
    Full-text · Article · Jul 2009 · Dermatology
  • Patrick A Oberholzer · Mirjana Urosevic · Hans C Steinert · Reinhard Dummer
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    ABSTRACT: Baseline staging is important in all melanoma types, including melanoma with unknown primary site (MUP). Staging includes different examination strategies, each with different accuracy. To determine the value of serum S100 protein levels and positron emission tomography (PET) in the baseline staging of MUP. Twenty patients with MUP were evaluable for the analysis between 1996 and 2007 with both S100 assessment and PET performed for baseline staging. Serum S100 was elevated in 7 patients (35%). The PET scan detected the metastases in 6 of 7 patients with elevated serum S100 protein showing a strong correlation (p = 0.005). Patients with metastases had significantly higher serum S100 levels (p = 0.01) than the ones without. Serum S100 protein was shown to be discriminative between patients with and without metastases (receiver-operating characteristic, p = 0.012) with 75% sensitivity and 92% specificity. Serum S100 protein appears to be a sensitive as well as specific marker to detect metastases. We therefore might recommend serum S100 assessment to be included in the baseline staging of MUP.
    No preview · Article · Oct 2008 · Dermatology
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    ABSTRACT: Liposomal pegylated doxorubicin is an encapsulation form of doxorubicin, with an improved pharmacokinetic profile and the ability to selectively accumulate into tumor tissue. As a result, the tolerated dose of the drug can be increased, followed by a reduced incidence of neutropenia and cardiotoxicity in comparison to doxorubucin treatment. However, a common adverse dose-schedule limiting effect of the treatment is palmoplantar erythrodysesthesia syndrome. In this retrospective study we included six patients hospitalised in the University Hospital of Zurich during the last 2 years, in connection with side effects caused by pegylated liposomal doxorubicin. These patients received this chemotherapeutic agent for treatment of various malignancies such as breast cancer, ovarian cancer, mycosis fungoides and cutaneous B-cell lymphoma. Three of six patients in this study developed classical palmoplantar erythrodysesthesia, one developed palmoplantar erythrodysesthesia associated with extensive bullous disease, one developed eruption of lymphocyte recovery syndrome and one developed intertrigo like dermatitis with stomatitis. Pegylated liposomal doxorubicin induces various skin reactions including palmoplantar erythrodysesthesia syndrome. However, the exact clinical presentation might depend on pre-existing skin diseases.
    Full-text · Article · Sep 2008 · European journal of dermatology: EJD
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    A Tun-Kyi · J-Z Qin · P A Oberholzer · A A Navarini · J C Hassel · R Dummer · U Döbbeling
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    ABSTRACT: Mycosis fungoides (MF) is the most frequent cutaneous T-cell lymphoma (CTCL). Arsenic trioxide (As(2)O(3)) has recently been shown to be effective against leukemias, so we studied whether As(2)O(3) induces apoptosis of CTCL cells in vitro. We further investigated if As(2)O(3) is effective in a MF mouse model. Annexin V/7-amino-actinomycin-D stainings were carried out to investigate if As(2)O(3) induced apoptosis of CTCL cell lines. To study the underlying mechanisms, the effects of As(2)O(3) on various transcription factors and apoptosis regulating proteins were analyzed by western blots, electrophoretic mobility shift assays and transcription factor enzyme-linked immunosorbent assays. The ability of As(2)O(3) to induce tumor regression was investigated in a MF mouse model. As(2)O(3)-induced apoptosis was paralleled by a reduction of the DNA-binding activities of transcription factors of the NFkB and signal transducer and activator of transcription gene families and reduced expression of the antiapoptotic proteins bcl-1, bcl-xL and mcl-1. Local injections of 200 muM As(2)O(3) into tumors caused complete remissions in five of six mice and one partial remission. As(2)O(3) induced apoptosis of CTCL cells by the down-regulation of transcription factors that stimulate the expression of antiapoptotic genes. Local injection of As(2)O(3) into MF tumor-bearing mice resulted in tumor regression.
    Full-text · Article · Apr 2008 · Annals of Oncology
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    ABSTRACT: Cutaneous melanoma is the most aggressive of cutaneous neoplasms. Identifying patients with an increased risk for the development of metastases is critical. This study investigates phospho-Smad2, a central factor of the transforming growth factor beta pathway, on formalin-fixed, paraffin-embedded tissues from 60 primary cutaneous melanomas (Breslow >1 mm), for its candidacy for being a prognostic marker in primary cutaneous melanoma. Phospho-Smad2 positivity was assessed for correlation with clinical parameters including Breslow index, melanoma type, survival, development of metastases, sentinel lymph node status and age. Phospho-Smad2 positivity was not associated with survival or development of metastases, suggesting that it would not be a useful prognostic marker. Despite this, we found phospho-Smad2 positivity to be correlated with low tumour thickness, indicating that as the primary tumour grows there is an increased inhibition of transforming growth factor beta signalling resulting in suppressed Smad2 phosphorylation. Additionally, phosphorylation of Smad2 in neighbouring melanoma cells and keratinocytes was interrelated, which is a further indication that Smad2 phosphorylation in primary melanoma is affected by local area microenvironmental factors. We hypothesize that the observed decrease in transforming growth factor beta signalling in thicker primary melanomas is due to the increased production of signalling inhibitors.
    No preview · Article · May 2007 · Melanoma Research
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    ABSTRACT: Measles virus (MV) has shown promise as an oncolytic virus in the treatment of different tumor models for human B-cell lymphoma, multiple myeloma, ovarian cancer, and glioma. We have shown that, in a phase I clinical trial, MV vaccine induces tumor regression in cutaneous T-cell lymphoma (CTCL) patients. Here, we investigated in detail, the effect of recombinant MV (rMV) vaccine strain in CTCL cell cultures, and in vivo in established CTCL xenografts in nude mice. The susceptibility of three CTCL cell lines, originating from patients, to rMV was tested by determination of cell surface expression of MV receptors. All cell lines expressed the receptors CD150 and CD46 and were easily infected by rMV and induced complete cell lysis. The cytoreductive activity was apparent in cells forming aggregates, indicating a cell-to-cell spread of MV and cytolysis owing to virus infection. Intratumoral (i.t.) injection of rMV, expressing enhanced green fluorescent protein induced complete regression of large established human CTCL tumors in nude mice, whereas tumors with control treatment progressed exponentially. Immunohistochemical analysis of tumor biopsies, after i.t. treatment, for MV-NP protein complex demonstrated replication of MV within the tumors. The data demonstrate the potential of MV as a therapeutic agent against CTCL.
    Full-text · Article · Dec 2006 · Journal of Investigative Dermatology
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    ABSTRACT: Lymph node (LN) status is an important prognostic factor in melanoma patients. p16 expression and proliferation rate (MIB-1) of primary melanomas have been suggested as a marker of metastatic potential. In this study, the correlation of p16 expression and the proliferation rate (MIB-1) with LN status and tumor-specific survival was investigated in primary melanomas. MIB-1 and p16 expression were analyzed by immunohistochemistry in 64 patients with primary cutaneous melanoma. Thirty four nevi were used as control. All patients underwent sentinel lymph node staging. Three different p16 staining patterns were observed: a combination of nuclear and cytoplasmic staining, only cytoplasmic staining and absence of p16 expression. All 34 nevi displayed a nuclear and cytoplasmic p16 staining, whereas p16 was negative in 14 of 64 (22%) melanomas. The level of p16 expression gradually decreased from benign nevi to melanoma without metastasis to melanoma with metastasis. There was a significant correlation between cytoplasmic p16 expression and absence of metastasis (p < 0.05). Death of disease correlated with absence of p16 immunostaining (p = 0.01). MIB-1 expression was not associated with survival. These results confirm the relevance of p16 expression as a prognostic marker in melanoma patients. In addition, it was shown that cytoplasmic immunostaining for p16 in primary melanoma might serve as a predictor of the LN status. Therefore, immunohistochemical evaluation for p16 expression is of potential value for treatment planning in melanoma surgery.
    Full-text · Article · May 2006 · International Journal of Cancer
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    ABSTRACT: Some cutaneous T-cell lymphomas, (CTCLs) clonal T cells are deficient in interferon signaling, making them promising targets for viral oncolysis. We evaluated cytopathic effects of measles virus (MV) in CTCL. CTCL cell lines and infiltrating lymphocytes in CTCL expressed MV receptors CD150 and CD46. In a phase 1 dose escalation trial a total of 16 injections of live MV, Edmonston-Zagreb vaccine strain, were given intratumorally to 5 patients with CTCL. Patients had antimeasles-serum antibodies and were pretreated with interferon-alpha to prevent uncontrolled virus spread. The well-tolerated treatment with MV resulted in clinical responses. Evaluation of biopsies, before and at 11 days after injection, by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated local viral activity with positive staining for MV nucleoprotein (NP), an increase of the interferon gamma (IFN-gamma)/CD4 and IFN-gamma/CD8 mRNA ratios and a reduced CD4/CD8 ratio. All patients demonstrated an increased antimeasles antibody titer after therapy. The data demonstrate that CTCLs are promising targets for an MV-based oncolytic therapy.
    Full-text · Article · Nov 2005 · Blood
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    ABSTRACT: Plasmid DNA encoding human interleukin 12 (IL-12) was produced under GMP conditions and injected into lesions of nine patients with malignant melanoma (stage IV) previously treated with both standard and nonstandard therapies. The treatment was based on efficacy in preclinical studies with melanoma in mice and gray horses. The DNA was applied in cycles, three injections per cycle, for up to seven cycles. Three therapy arms comprised low (2 mg), medium (4 mg), and high (10 to 20 mg) amounts of total DNA. The therapy was well tolerated. Three of nine patients experienced a clinical response: two stable disease and one complete remission. One patient receiving a low dose of DNA experienced a long-lasting stabilization of the disease for more than 3 years, whereas the other two responders received high doses of DNA. All patients but one (patient 9) experienced a transient response at the intratumoral injection site. Immunohistochemical staining of responder sections showed local reduction of angiogenesis and lymphocyte infiltrations. All patients, in particular the clinical and local responders (patients 3, 7, and 8), exhibited an antigen-specific immune response against MAGE-1 and MART-1, which in some cases preexisted. Biopsies of responders showed some increase in IL-12, IP-10, and IFN-(). Serum levels revealed fluctuations. The results show that intratumoral injection of DNA produced some beneficial clinical effect. DNA encoding a cytokine may be useful as a therapeutic or adjuvant against various human cancers.
    Full-text · Article · Feb 2005 · Human Gene Therapy

Publication Stats

938 Citations
114.56 Total Impact Points

Institutions

  • 2012
    • Inselspital, Universitätsspital Bern
      Berna, Bern, Switzerland
  • 2011
    • Dana-Farber Cancer Institute
      Boston, Massachusetts, United States
  • 2009-2011
    • Harvard University
      Cambridge, Massachusetts, United States
  • 2004-2009
    • University of Zurich
      • Dermatologische Klinik und Poliklinik
      Zürich, Zurich, Switzerland
  • 2006
    • University Hospital Zürich
      Zürich, Zurich, Switzerland