Bio

Professional Education


  • Doctor of Medicine, Heinrich-Heine-University (2006)

Stanford Advisors


Research & Scholarship

Lab Affiliations


Publications

Journal Articles


  • Engineered SIRP alpha Variants as Immunotherapeutic Adjuvants to Anticancer Antibodies SCIENCE Weiskopf, K., Ring, A. M., Ho, C. C., Volkmer, J., Levin, A. M., Volkmer, A. K., Oezkan, E., Fernhoff, N. B., van de Rijn, M., Weissman, I. L., Garcia, K. C. 2013; 341 (6141): 88-91
  • Use of a KIT-specific monoclonal antibody to bypass imatinib resistance in gastrointestinal stromal tumors ONCOIMMUNOLOGY Edris, B., Willingham, S., Weiskopf, K., Volkmer, A. K., Volkmer, J., Muehlenberg, T., Weissman, I. L., van de Rijn, M. 2013; 2 (6)

    View details for DOI 10.4161/onci.24452

    View details for Web of Science ID 000322060900007

  • Anti-KIT monoclonal antibody inhibits imatinib-resistant gastrointestinal stromal tumor growth PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Edris, B., Willingham, S. B., Weiskopf, K., Volkmer, A. K., Volkmer, J., Muehlenberg, T., Montgomery, K. D., Contreras-Trujillo, H., Czechowicz, A., Fletcher, J. A., West, R. B., Weissman, I. L., van de Rijn, M. 2013; 110 (9): 3501-3506

    Abstract

    Gastrointestinal stromal tumor (GIST) is the most common sarcoma of the gastrointestinal tract and arises from the interstitial cells of Cajal. It is characterized by expression of the receptor tyrosine kinase CD117 (KIT). In 70-80% of GIST cases, oncogenic mutations in KIT are present, leading to constitutive activation of the receptor, which drives the proliferation of these tumors. Treatment of GIST with imatinib, a small-molecule tyrosine kinase inhibitor, inhibits KIT-mediated signaling and initially results in disease control in 70-85% of patients with KIT-positive GIST. However, the vast majority of patients eventually develop resistance to imatinib treatment, leading to disease progression and posing a significant challenge in the clinical management of these tumors. Here, we show that an anti-KIT monoclonal antibody (mAb), SR1, is able to slow the growth of three human GIST cell lines in vitro. Importantly, these reductions in cell growth were equivalent between imatinib-resistant and imatinib-sensitive GIST cell lines. Treatment of GIST cell lines with SR1 reduces cell-surface KIT expression, suggesting that mAb-induced KIT down-regulation may be a mechanism by which SR1 inhibits GIST growth. Furthermore, we also show that SR1 treatment enhances phagocytosis of GIST cells by macrophages, indicating that treatment with SR1 may enhance immune cell-mediated tumor clearance. Finally, using two xenotransplantation models of imatinib-sensitive and imatinib-resistant GIST, we demonstrate that SR1 is able to strongly inhibit tumor growth in vivo. These results suggest that treatment with mAbs targeting KIT may represent an alternative, or complementary, approach for treating GIST.

    View details for DOI 10.1073/pnas.1222893110

    View details for Web of Science ID 000315841900062

    View details for PubMedID 23382202

  • Antibody therapy targeting the CD47 protein is effective in a model of aggressive metastatic leiomyosarcoma PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Edris, B., Weiskopf, K., Volkmer, A. K., Volkmer, J., Willingham, S. B., Contreras-Trujillo, H., Liu, J., Majeti, R., West, R. B., Fletcher, J. A., Beck, A. H., Weissman, I. L., van de Rijn, M. 2012; 109 (17): 6656-6661

    Abstract

    Antibodies against CD47, which block tumor cell CD47 interactions with macrophage signal regulatory protein-?, have been shown to decrease tumor size in hematological and epithelial tumor models by interfering with the protection from phagocytosis by macrophages that intact CD47 bestows upon tumor cells. Leiomyosarcoma (LMS) is a tumor of smooth muscle that can express varying levels of colony-stimulating factor-1 (CSF1), the expression of which correlates with the numbers of tumor-associated macrophages (TAMs) that are found in these tumors. We have previously shown that the presence of TAMs in LMS is associated with poor clinical outcome and the overall effect of TAMs in LMS therefore appears to be protumorigenic. However, the use of inhibitory antibodies against CD47 offers an opportunity to turn TAMs against LMS cells by allowing the phagocytic behavior of resident macrophages to predominate. Here we show that interference with CD47 increases phagocytosis of two human LMS cell lines, LMS04 and LMS05, in vitro. In addition, treatment of mice bearing subcutaneous LMS04 and LMS05 tumors with a novel, humanized anti-CD47 antibody resulted in significant reductions in tumor size. Mice bearing LMS04 tumors develop large numbers of lymph node and lung metastases. In a unique model for neoadjuvant treatment, mice were treated with anti-CD47 antibody starting 1 wk before resection of established primary tumors and subsequently showed a striking decrease in the size and number of metastases. These data suggest that treatment with anti-CD47 antibodies not only reduces primary tumor size but can also be used to inhibit the development of, or to eliminate, metastatic disease.

    View details for DOI 10.1073/pnas.1121629109

    View details for Web of Science ID 000303249100064

    View details for PubMedID 22451919

  • The CD47-signal regulatory protein alpha (SIRPa) interaction is a therapeutic target for human solid tumors PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Willingham, S. B., Volkmer, J., Gentles, A. J., Sahoo, D., Dalerba, P., Mitra, S. S., Wang, J., Contreras-Trujillo, H., Martin, R., Cohen, J. D., Lovelace, P., Scheeren, F. A., Chao, M. P., Weiskopf, K., Tang, C., Volkmer, A. K., Naik, T. J., Storm, T. A., Mosley, A. R., Edris, B., Schmid, S. M., Sun, C. K., Chua, M., Murillo, O., Rajendran, P., Cha, A. C., Chin, R. K., Kim, D., Adorno, M., Raveh, T., Tseng, D., Jaiswal, S., Enger, P. O., Steinberg, G. K., Li, G., So, S. K., Majeti, R., Harsh, G. R., van de Rijn, M., Teng, N. N., Sunwoo, J. B., Alizadeh, A. A., Clarke, M. F., Weissman, I. L. 2012; 109 (17): 6662-6667

    Abstract

    CD47, a "don't eat me" signal for phagocytic cells, is expressed on the surface of all human solid tumor cells. Analysis of patient tumor and matched adjacent normal (nontumor) tissue revealed that CD47 is overexpressed on cancer cells. CD47 mRNA expression levels correlated with a decreased probability of survival for multiple types of cancer. CD47 is a ligand for SIRP?, a protein expressed on macrophages and dendritic cells. In vitro, blockade of CD47 signaling using targeted monoclonal antibodies enabled macrophage phagocytosis of tumor cells that were otherwise protected. Administration of anti-CD47 antibodies inhibited tumor growth in orthotopic immunodeficient mouse xenotransplantation models established with patient tumor cells and increased the survival of the mice over time. Anti-CD47 antibody therapy initiated on larger tumors inhibited tumor growth and prevented or treated metastasis, but initiation of the therapy on smaller tumors was potentially curative. The safety and efficacy of targeting CD47 was further tested and validated in immune competent hosts using an orthotopic mouse breast cancer model. These results suggest all human solid tumor cells require CD47 expression to suppress phagocytic innate immune surveillance and elimination. These data, taken together with similar findings with other human neoplasms, show that CD47 is a commonly expressed molecule on all cancers, its function to block phagocytosis is known, and blockade of its function leads to tumor cell phagocytosis and elimination. CD47 is therefore a validated target for cancer therapies.

    View details for DOI 10.1073/pnas.1121623109

    View details for Web of Science ID 000303249100065

    View details for PubMedID 22451913

  • Combination of a MDR1-targeted replicative adenovirus and chemotherapy for the therapy of pretreated ovarian cancer JOURNAL OF CANCER RESEARCH AND CLINICAL ONCOLOGY Rein, D. T., Volkmer, A., Bauerschmitz, G., Beyer, I. M., Janni, W., Fleisch, M. C., Welter, A. K., Bauerschlag, D., Schoendorf, T., Breidenbach, M. 2012; 138 (4): 603-610

    Abstract

    Targeted oncolytic adenoviruses capable of replication selectively in cancer cells are an appealing approach for the treatment of various cancer types refractory to conventional therapies. The aim of this study was to evaluate the effect of Ad5/3MDR1E1, a multidrug resistance gene 1 (MDR1)-targeted fiber-modified replication-competent adenovirus for the therapy of platinum-pretreated ovarian cancer in combination with cytostatic agents.MDR1-specific tumor cell killing of Ad5/3MDR1E1 was systematically evaluated in chemotherapy naïve and pretreated ovarian cancer cells in vitro. Combinations of Ad5/3MDR1E1 and cytostatic agents were studied in vivo and in vitro. An in vivo hepatotoxicity model was used to evaluate liver toxicity.We demonstrate efficient oncolysis of Ad5/3MDR1E1 in chemotherapy-resistant ovarian cancer cells as well as therapeutic efficacy in an orthotopic mouse model. Further, combining Ad5/3MDR1E1 with paclitaxel resulted in greater therapeutic benefit than either agent alone.These preclinical data suggest that a fiber-modified adenovirus vector under the control of the MDR1 promoter represents a promising treatment strategy for platinum-pretreated ovarian cancer as a single agent or in combination with conventional anticancer drugs.

    View details for DOI 10.1007/s00432-011-1135-5

    View details for Web of Science ID 000301836000007

    View details for PubMedID 22209976

  • Systemic administration of bevacizumab prolongs survival in an in vivo model of platinum pre-treated ovarian cancer. Oncology letters Rein, D. T., Volkmer, A. K., Volkmer, J., Beyer, I. M., Janni, W., Fleisch, M. C., Welter, A. K., Bauerschlag, D., Schöndorf, T., Breidenbach, M. 2012; 3 (3): 530-534

    Abstract

    Ovarian cancer patients often suffer from malignant ascites and pleural effusion. Apart from worsening the outcome, this condition frequently impairs the quality of life in patients who are already distressed by ovarian cancer. This study investigated whether single intraperitoneal administration of the anti-VEGF antibody bevacizumab is capable of reducing the ascites-related body surface and prolonging survival. The study was performed in an orthotopic murine model of peritoneal disseminated platin-resistant ovarian cancer. Mice were treated with bevacizumab and/or paclitaxel or buffer (control). Reduction of body surface and increased survival rates were assessed as therapeutic success. Survival of mice in all treatment groups was significantly enhanced when compared to the non-treatment control group. The combination of paclitaxel plus bevacizumab significantly improved body surface as well as overall survival in comparison to a treatment with only one of the drugs. Treatment of malignant effusion with a single dose of bevacizumab as an intraperitoneal application, with or without cytostatic co-medication, may be a powerful alternative to systemic treatment.

    View details for PubMedID 22740945

  • Hysteroscopic Management of Residual Trophoblastic Tissue Is Superior to Ultrasound-Guided Curettage JOURNAL OF MINIMALLY INVASIVE GYNECOLOGY Rein, D. T., Schmidt, T., Hess, A. P., Volkmer, A., Schoendorf, T., Breidenbach, M. 2011; 18 (6): 774-778

    Abstract

    The aim of this study was to estimate the rate of intrauterine adhesions and subsequent pregnancy outcome in patients with residual trophoblastic tissue treated with hysteroscopic resection versus ultrasound-guided dilation and evacuation (D&E).Cohort study from 2 centers (Canadian Task Force classification II-2).Two surgical teams at the University of Duesseldorf Medical Center and the PAN Clinic in Cologne, Germany.Women with residual trophoblastic tissue after first- or second-trimester miscarriage or term delivery.Two techniques were used for the removal of residual trophoblastic tissue: ultrasound-guided evacuation with a curette (D&E) and hysteroscopic resection of trophoblastic tissue (HR).We evaluated 95 patients who underwent secondary intervention for residual trophoblastic disease. A total of 42 patients underwent dilation of the cervix and ultrasound-guided curettage. In a second series of 53 patients, a resectoscope fitted with a 4-mm cutting loop was used for the removal of residual trophoblastic tissue used without application of current. Three months after the intervention, second-look office hysteroscopy was performed. Differences between both treatment groups were statistically significant. After HR, mild intrauterine adhesions were found in 2 patients (4.2%). After D&E, 12 patients (30.8%) presented with intrauterine adhesions (mild intrauterine adhesions: n = 7 [17.9%]; single dense adhesions: n = 3 [7.7%]; and extensive endometrial fibrosis n = 1 [2.6%]). Eighty-two patients wanted to become pregnant. Conception rate of all patients examined was 68.8% (HR) and 59.9% (D&E) (p < .05). In patients younger than 35 years of age who underwent HR, the pregnancy rate was significantly (p < .05) increased compared with patients who underwent D&E (78.1% vs 66.6%). In addition, patients from the HR group demonstrated a significantly (p < .05) shorter time to conception (11.5 month vs 14.5 month).The results of this study indicate that selective HR of residual trophoblastic tissue significantly reduces the incidence of intrauterine adhesions and increases pregnancy rates.

    View details for DOI 10.1016/j.jmig.2011.08.003

    View details for Web of Science ID 000296942100017

    View details for PubMedID 22024264

  • Treatment of chemotherapy resistant ovarian cancer with a MDR1 targeted oncolytic adenovirus GYNECOLOGIC ONCOLOGY Rein, D. T., Volkmer, A., Beyer, I. M., Curiel, D. T., Janni, W., Dragoi, A., Hess, A. P., Maass, N., Baldus, S. E., Bauerschmitz, G., Breidenbach, M. 2011; 123 (1): 138-146

    Abstract

    Multidrug resistance gene 1 (MDR1) mediated resistance to chemotherapeutic agents is a major obstacle for the therapy of various cancer types. The use of conditionally replicating adenoviruses (CRAds) is dependent on molecular differences between tumor cells and non tumor cells. Transcriptional targeting of CRAd replication is an effective way to control replication regulation. The aim of this study was to evaluate the effect of a MDR1 targeted fiber-modified CRAd against chemotherapy resistant ovarian cancer.MDR1 expression was evaluated in chemotherapy naïve and pretreated ovarian cancer cells and various control cells. We constructed 2 variants of a fiber-modified CRAd, Ad5/3MDR1E1 and Ad5/3MDR1E1?24 containing the MDR1 promoter to control viral replication via the E1A gene. The MDR promoter activity and cell killing efficacy were evaluated in vitro. Orthotopic murine models of peritoneally disseminated ovarian cancer were utilized to evaluate the preclinical efficacy of MDR targeted CRAds in vivo. To evaluate the liver toxicity of MDR1 targeted CRAds, we compared Ad5/3MDR1E1 with Ad5/3?24, a CRAd that replicates in cancer cells inactive in the Rb/p16 pathway by use of an in vivo hepatotoxicity model.We demonstrate efficient oncolysis of Ad5/3MDR1E1 in both chemotherapy resistant ovarian cancer cell lines and in primary tumor cells from pretreated patients as well as therapeutic efficacy in an orthotopic mouse model. Ad5/3MDR1E1 demonstrated significantly decreased liver toxicity compared to other 5/3-fiber modified control vectors examined.In summary, Ad5/3MDR1E1 is an efficient and safe gene therapy approach for specific targeting of chemotherapy resistant cancer cells.

    View details for DOI 10.1016/j.ygyno.2011.06.007

    View details for Web of Science ID 000295208500025

    View details for PubMedID 21741695

  • Modifications of Laparoscopic Supracervical Hysterectomy Technique Significantly Reduce Postoperative Spotting JOURNAL OF MINIMALLY INVASIVE GYNECOLOGY Schmidt, T., Eren, Y., Breidenbach, M., Fehr, D., Volkmer, A., Fleisch, M., Rein, D. T. 2011; 18 (1): 81-84

    Abstract

    The aim of this study was to estimate the benefit of excision of the endocervix during laparoscopic supracervical hysterectomy (LSH) with regard to postoperative cyclical bleeding.Cohort study from 2 centers (Canadian Task Force classification II-2).Two surgical teams at the University of Duesseldorf Medical Center and PAN Clinic, Cologne, Germany.Women with menstrual bleeding disorders resistant to medical treatment, symptomatic leiomyomata, dysmenorrhea.Laparoscopic supracervical hysterectomy. The uterus was transsected from the cervix with 2 techniques with and without excision of cervical canal.We evaluated 300 patients who underwent consecutive LSH procedures. In 150 patients the uterus was transsected from the cervix using a monopolar loop. In a second series of 150 patients a unipolar needle electrode was used for the uterine amputation and the excision of cervical canal. The mean duration of the transsection was 65 seconds (monopolar loop) versus 168 seconds (monopolar needle). The excision of the endocervix was performed without any complications in 148 procedures. Histologic examination of the removed tissue revealed endocervical tissue in 83.3% (n = 125), endometrium in 9.4% (n = 14), cervicoisthmic mucosa in 3.3% (n = 5), and myometrium only in 4% (n = 4). All 300 patients were contacted 12 months after surgery to inquire about bleeding status, and 282 (94%) responded. In patients who underwent excision of the endocervix, postoperative cyclical bleeding was significantly reduced compared with the control group (1.4% vs 10.7%).The results of this study indicate that the routine excision of the endocervix is a quick safe procedure which allows a significant reduction of postoperative cyclical bleeding in patients who undergo LSH.

    View details for DOI 10.1016/j.jmig.2010.09.014

    View details for Web of Science ID 000286286100016

    View details for PubMedID 21094098

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