The overall goal of our program is to develop more effective therapies for patients with mesothelioma using monoclonal antibodies direcetd to tumor differentiation antigens. Our current studies are focused on using immunotherapy directed against the tumor differentiation antigen mesothelin that is highly expressed in many cancers including malignant mesothelioma. Mesothelin, a tumor differentiation antigen is expressed on normal mesothelial cells lining the pleura, pericardium and peritoneum but it is highly expressed in several human tumors especially mesothelioma, ovarian, lung and pancreatic adenocarcinomas. This differential expression of mesothelin makes it an attractive candidate for tumor specific therapy. Our efforts are now focused on exploiting it for mesothelioma therapy using different approaches. These include a chimeric anti-mesothelin monoclonal antibody (MORAb-009);anti mesothelin immunotoxin (SS1P) and an anti-mesothelin drug conjugate (BAY 94-9343). SS1P is a recombinant immunotoxin consisting of the anti-mesothelin Fv linked to a truncated form of the potent bacterial toxin, Pseudomonas exotoxin A. We have previously established the safety and maximum tolerated dose (MTD) of SS1P in phase I clinical trials. Our laboratory studies showing synergy between SS1P and chemotherapy has led to our clinical trial of SS1P in combination with pemetrexed and cisplatin in chemo-nave patients with pleural mesothelioma. Results of this study show a very high response rate with 8 out of the 13 evaluable patients treated at the maximum tolerated dose (MTD) having partial responses. While the results of this trial are exciting we are also interested in increasing the efficacy of SS1P. Since SS1P is an immunogenic protein majority of patients develop neutralizing antibodies to it that limits treatment to 1 to 2 cycles. My laboratory in collaboration with the Pastan group and the laboratory Dr. Dan Fowler at the NCI have shown that treatment with pentostatin plus cyclophosphamide abrogates the generation of immune response to SS1P in immunocompetent mice. Based on these results we are doing a pilot study to see in patients if pentostatin plus cyclophosphamide can decrease the immunogenicity of SS1P in patients with chemo-refractory mesothelioma and allow repeated administration of SS1P. We have also completed the single arm phase II clinical trial of MORAb-009 with pemetrexed and cisplatin for front-line therapy of pleural mesothelioma. This clinical trial has met its accrual goal with 89 patients enrolled and is awaiting data analysis. We are also conducting a phase I clinical trial to determine the safety and MTD of the anti-mesothelin antibody drug conjugate BAY 94-9343, which consists of a humanized anti-mesothelin monoclonal antibody linked to the maytansinoid DM4. This trial is also being conducted at M.D.Anderson and at Sarah Canon Research Center. The MTD has been established and patients are now being treated at the various expansion cohorts. In the laboratory we have focused on developing in-vitro and in-vivo models of human mesothelioma. We have established and characterized several early passage tumor cells obtained from ascites and pleural fluid of patients with mesothelioma. We have fully characterized these cells for morphological and molecular characteristics. These models are essential to evaluate novel therapeutic agents being developed in LMB but should be valuable to other scientists studying mesothelioma.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Investigator-Initiated Intramural Research Projects (ZIA)
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National Cancer Institute Division of Basic Sciences
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Pastan, Ira; Hassan, Raffit (2014) Discovery of mesothelin and exploiting it as a target for immunotherapy. Cancer Res 74:2907-12
Hassan, Raffit; Kindler, Hedy L; Jahan, Thierry et al. (2014) Phase II clinical trial of amatuximab, a chimeric antimesothelin antibody with pemetrexed and cisplatin in advanced unresectable pleural mesothelioma. Clin Cancer Res 20:5927-36
Keenan, Bridget P; Saenger, Yvonne; Kafrouni, Michel I et al. (2014) A Listeria vaccine and depletion of T-regulatory cells activate immunity against early stage pancreatic intraepithelial neoplasms and prolong survival of mice. Gastroenterology 146:1784-94.e6
Miller, Andrew C; Miettinen, Markku; Schrump, David S et al. (2014) Malignant mesothelioma and central nervous system metastases. Report of two cases, pooled analysis, and systematic review. Ann Am Thorac Soc 11:1075-81
Hassan, Raffit; Sharon, Elad; Thomas, Anish et al. (2014) Phase 1 study of the antimesothelin immunotoxin SS1P in combination with pemetrexed and cisplatin for front-line therapy of pleural mesothelioma and correlation of tumor response with serum mesothelin, megakaryocyte potentiating factor, and cancer antigen Cancer :
Weldon, John E; Xiang, Laiman; Zhang, Jingli et al. (2013) A recombinant immunotoxin against the tumor-associated antigen mesothelin reengineered for high activity, low off-target toxicity, and reduced antigenicity. Mol Cancer Ther 12:48-57
Schaub, Nicholas P; Alimchandani, Meghna; Quezado, Martha et al. (2013) A novel nomogram for peritoneal mesothelioma predicts survival. Ann Surg Oncol 20:555-61
Carpenito, Carmine; Milone, Michael C; Hassan, Raffit et al. (2009) Control of large, established tumor xenografts with genetically retargeted human T cells containing CD28 and CD137 domains. Proc Natl Acad Sci U S A 106:3360-5
Kreitman, Robert J; Hassan, Raffit; Fitzgerald, David J et al. (2009) Phase I trial of continuous infusion anti-mesothelin recombinant immunotoxin SS1P. Clin Cancer Res 15:5274-9