No abstract

The epidermal growth factor receptor directed antibody, cetuximab, is an effective clinical therapy for patients with colorectal, head and neck and non-small cell lung cancer patients particularly for those with KRAS and BRAF wild type cancers. Treatment in all patients is limited eventually by the development of acquired resistance but little is known about the underlying mechanism. Here we show, that activation of ERBB2 signaling, either through ERBB2 amplification or through heregulin upregulation, leads to persistent ERK 1/2 signaling and consequently cetuximab resistance. Inhibition of ERBB2 or disruption of ERBB2/ERBB3 heterodimerization restores cetuximab sensitivity in vitro and in vivo. A subset of colorectal cancer patients that exhibit either de novo or acquired resistance to cetuximab based therapy possess ERBB2 amplification or high levels of circulating heregulin. Collectively, these findings identify two distinct resistance mechanisms, both of which promote aberrant ERBB2 signaling, that mediate cetuximab resistance. Moreover, these results suggest that ERBB2 inhibitors, in combination with cetuximanb, represent a rational therapeutic strategy that should be assessed in cetuximab-resistant cancers.

This study strongly suggests that cisplatin plus etoposide and concurrent radiotherapy is more effective for the treatment of LS-SCLC than cisplatin plus etoposide and sequential radiotherapy.

Docetaxel improved progression-free survival, response rate, and disease-related symptoms versus vinorelbine. Overall survival was not statistically significantly improved at this time. Docetaxel monotherapy may be considered as an option in the standard treatment of elderly patients with advanced NSCLC.

PS and smoking status are independent prognostic factors for OS in NSCLC.

Erlotinib failed to show an improvement in PFS or OS compared with docetaxel in an EGFR-unselected patient population.

Caspase-3(-like) proteases play important roles in controlling mammalian apoptosis. However, the downstream events from the caspase-3(-like) protease activation to death of cells are still unclear. Previously, we reported that hydrogen peroxide (H 2 O 2 ) was generated by the activation of caspase-3(-like) proteases in the process of tyrosine kinase inhibitor-induced apoptosis in human small cell lung carcinoma Ms-1 cells. In the present study, we examined whether generation of H 2 O 2 is a critical event for the apoptotic pathway downstream of caspase-3(-like) protease activation by various anticancer drugs. Anticancer drugs such as camptothecin, vinblastine, inostamycin, and adriamycin induced activation of caspase-3(-like) proteases and apoptosis. Generation of H 2 O 2 was commonly detected after treatment with each of the four anticancer drugs, and scavenging of H 2 O 2 caused cells to fail to undergo apoptosis. Moreover, anticancer drug-induced H 2 O 2 production was inhibited not only by an inhibitor of caspase-3(-like) proteases but also by diphenyleneiodonium chloride, an inhibitor of flavonoid-containing enzymes such as NADPH oxidase. However, activation of caspase-3(-like) proteases was not inhibited by diphenyleneiodonium chloride. These findings suggest that activation of caspase-3(-like) proteases by various anticancer drugs causes generation of H 2 O 2 presumably through the activation of NADPH oxidase, thereby inducing apoptosis.

CPT-11 is an active agent against refractory or relapsed SCLC and deserves to be studied more closely as both a single agent and in combination with other drugs to treat patients with SCLC.