Study of Carfilzomib With Irinotecan in Irinotecan-Sensitive Malignancies and Small Cell Lung Cancer Patients

Small cell lung cancer accounts for approximately 15% of all lung cancer diagnoses in the United States (US), with 60-80% response rates to platinum-based chemotherapy in extensive disease. Despite its sensitivity to chemotherapy, small cell lung cancer is characterized by its tendency to spread to other locations in the body such as the bloodstream and other organs such as the liver. Currently, the only FDA-approved second-line therapies are oral and parenteral topotecan, although irinotecan is also commonly used in primary and relapsed disease. Novel combination therapies are desperately needed in this disease. in order to improve survival. Carfilzomib (also known as Kyprolis) is an anti-cancer drug classified as a selective proteasome inhibitor. Proteasome inhibition affects the levels of numerous cell cycle control proteins, apoptosis (i.e., cell death), cell adhesion, angiogenesis, and chemoresistance proteins. Chemically, it is similar to epoxomicin. Carfilzomib and other proteasome inhibitors interrupt cellular pathways integral to the survival of small cell lung cancer, namely the apoptotic pathway involving activated Nuclear Factor-kB (referenced as NF-kB). NF-kB activates the transcription of anti-apoptotic and proliferation genes, mediating tumor cell survival in response to cytotoxic stress thus resulting in chemoresistance, a common problem in small cell lung cancer. Carfilzomib prevents the breakdown of IkappaB (referenced as IkB), a protein which inhibits NF-kB, controls levels of the anti-apoptotic gene Bcl-2 and the tumor suppressor p53. Overexpression of Bcl-2, a key mediator of resistance to apoptosis following chemotherapy, which is an important problem in small cell lung cancer. In this trial, Carfilzomib is combined with Irinotecan. Irinotecan, a camptothecins, inhibits topoisomerase I, thought to be important in the growth and spread of cancer. As a class, camptothecins have shown efficacy in small cell lung cancer in a variety of settings. Topoisomerase-1 is thought to cause apoptosis via mechanisms other than NF-kB, adding to the potential synergy of these compounds. In addition, topoisomerase-1 is overexpressed in the majority of subjects with small cell lung cancer and decreased degradation of this enzyme is expected to lead to further enhancement of this mechanism of apoptosis The pivotal phase III study which led to FDA approval of topotecan in relapsed small cell lung cancer was by Von Pawel et al, and included 211 subjects with sensitive (\> 60 days since prior therapy) relapse and randomized them to either topotecan (107 subjects) daily for 5 days or to cyclophosphamide, doxorubicin, and vincristine (CAV), each given every 21 days. Topotecan showed no significant improvement in the median time to progression (13.3 weeks vs.12.3 weeks, p=0.552) or median survival (25 weeks vs. 24.7 weeks, p=0.795), however, subjects treated with topotecan had improvement in cancer-related symptoms (dyspnea, hoarseness, anorexia, and fatigue) as well as hematologic toxicity. Irinotecan, has established activity in small cell lung cancer, as well as non-small cell lung cancer, colorectal cancer and ovarian cancer. In this Phase 2 study patients will be treated with the Maximum Tolerated Dose (MTD) of Carfilzomib 20/36 mg/m\^2 as stepped up dosing determined in Phase 1b and 125mg/m\^2 of Irinotecan.