RESUMO
Human epidermal growth factor receptor 2 (HER2) is an oncogenic driver, and a well-established therapeutic target in breast and gastric cancers. Using functional and genomic analyses of patient-derived xenografts, we previously showed that a subset (approximately 5%) of metastatic colorectal cancer (CRC) tumors is driven by amplification or mutation of HER2. This paper reviews the role of HER2 amplification as an oncogenic driver, a prognostic and predictive biomarker, and a clinically actionable target in CRC, considering the specifics of HER2 testing in this tumor type. While the role of HER2 as a biomarker for prognosis in CRC remains uncertain, its relevance as a therapeutic target has been established. Indeed, independent studies documented substantial clinical benefit in patients treated with biomarker-driven HER2-targeted therapies, with an impact on response rates and duration of response that compared favorably with immunotherapy and other examples of precision oncology. HER2-targeted therapeutic strategies have the potential to change the treatment paradigm for a clinically relevant subgroup of metastatic CRC patients.
Assuntos
Antineoplásicos Imunológicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Colorretais/terapia , Recidiva Local de Neoplasia/prevenção & controle , Receptor ErbB-2/antagonistas & inibidores , Antineoplásicos Imunológicos/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Biomarcadores Tumorais/análise , Biomarcadores Tumorais/antagonistas & inibidores , Biomarcadores Tumorais/genética , Biópsia , Quimioterapia Adjuvante/métodos , Ensaios Clínicos como Assunto , Neoplasias Colorretais/genética , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Intervalo Livre de Doença , Amplificação de Genes , Testes Genéticos , Humanos , Terapia de Alvo Molecular/métodos , Terapia Neoadjuvante/métodos , Recidiva Local de Neoplasia/genética , Recidiva Local de Neoplasia/patologia , Medicina de Precisão/métodos , Prognóstico , Intervalo Livre de Progressão , Receptor ErbB-2/análise , Receptor ErbB-2/genéticaRESUMO
OBJECTIVE: Anti-CD20 chimeric monoclonal antibody rituximab (Mabthera; IDEC-C2B8) is currently tested in several clinical trials for the treatment of B-cell chronic lymphocytic leukemia (B-CLL). In the present study, we investigated whether rituximab therapy may select for CD20(-) subclones. MATERIALS AND METHODS: Leukemic B-CLL cells were isolated from patients with B-CLL and sensitivity to rituximab-induced cell death was examined. Levels of CD20 protein and mRNA were determined using flow cytometry and real-time PCR, respectively. Clonality analyses of leukemic cells throughout rituximab therapy were performed by GeneScan analysis of patient clone specific rearrangements of the complementarity determining region III of the heavy chain immunoglobulin. RESULTS: Cytotoxicity of rituximab in vitro did not depend on the protein levels of CD20. During therapy with rituximab CD20(+) B-CLL cells were depleted and CD20(-) leukemic cells emerged. After treatment, the initial CD20(+) B-CLL cell clone reexpanded. CD20(-) B-CLL cells retained their capacity to synthesize the CD20 molecule. CONCLUSIONS: These data support the concept that in B-CLL rituximab treatment may not lead to the emergence of CD20(-) leukemic variants. Our findings support clinical studies investigating the benefit of prolonged period of rituximab therapy in B-CLL disease.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Antígenos CD20/genética , Antineoplásicos/uso terapêutico , Leucemia Linfocítica Crônica de Células B/tratamento farmacológico , Anticorpos Monoclonais Murinos , Sequência de Bases , Primers do DNA , Regulação Neoplásica da Expressão Gênica , Variação Genética , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/imunologia , Leucemia Linfocítica Crônica de Células B/patologia , Reação em Cadeia da Polimerase , RNA Mensageiro/genética , Rituximab , Transcrição GênicaRESUMO
Rituximab (IDEC-C2B8) is a chimeric antibody that binds to the B-cell surface antigen CD20. Rituximab has significant activity in follicular non-Hodgkin lymphomas. Much less is known about the effects in chronic lymphocytic leukemia (CLL). We have initiated a phase II trial to evaluate the efficacy and safety of rituximab in patients with CD20+ pretreated CLL. To avoid the rituximab-associated toxicity, we restricted the tumor cell load, as measured by the number of circulating lymphocytes and the spleen size, in the first 2 cohorts of patients included in the study. Patients received 4 intravenous infusions of 375 mg/m2 once a week over a period of 1 month. Of the 28 patients evaluable for response, 7 patients showed a partial remission (National Cancer Institute criteria) lasting for a median of 20 weeks, with 1 patient still in remission after 71 weeks. Based on lymphocyte counts only, we found at least a 50% reduction of lymphocyte counts lasting for at least 4 weeks in 13 (45%) of 29 patients. Fifteen patients from 3 institutions were monitored for the immunophenotype profile of lymphocyte subsets. The number of CD5+CD20+ cells decreased significantly and remained low until day 28 after therapy. T-cell counts were not affected. With the exception of one rituximab-related death, adverse events in the remaining patients were mild. The results suggest that rituximab has clinical activity in pretreated patients with B-CLL. Toxicity is tolerable. Response duration after withdrawal of rituximab is rather short. Therefore, other modes of application and the combination with other agents need to be tested.
