Isamu Okamoto

Activation of ERBB2 Signaling Causes Resistance to the EGFR-Directed Therapeutic Antibody Cetuximab

Several cancers become resistant to cetuximab by activating a bypass signaling pathway and preventing cetuximab inhibition of ERK1/2-stimulated growth. Combating Resistance to an EGF Receptor Inhibitor Many promising anticancer drugs are effective only for a limited time, because the tumor cells develop resistance. Cetuximab, directed against the epidermal growth factor receptor (EGFR), is no exception, and patients with colorectal, head and neck, or non–small cell lung cancer eventually cease to respond to the drug. Yonesaka and colleagues have determined that cetuximab-resistant cancer cells—both in culture and in patients—can up-regulate signaling through the ERBB2 growth factor receptor in several ways, permanently turning on extracellular signal–regulated kinase 1/2 (ERK1/2)–mediated growth, differentiation, and survival. They further show that interference with the ERBB2 pathway restores the ability of cetuximab to control these cancers, pointing to a promising resistance-fighting approach. The authors generated clones of cetuximab-resistant non–small cell lung and colorectal cancer cell lines by exposing the cells to increasing concentration of the drug. In some of these resistant clones, the ERBB2 receptor oncogene was genetically amplified, resulting in activated ERK1/2 signaling. Down-regulation of ERBB2 with a small interfering RNA or antibody restored sensitivity. Other clones did not have amplified ERBB2 genes but did make excess heregulin, an activating ligand for the ERBB2 receptor. Heregulin depletion or ERBB2 inhibition restored cetuximab sensitivity. After replicating these studies in xenografts in mice, the authors also looked for evidence that these resistance-associated alterations pertain to human tumors. In several groups of patients with colorectal cancer, they saw decreased survival or decreased sensitivity to cetuximab in those who exhibited amplified ERBB2 gene or higher heregulin concentrations. The concordance of their cellular data with patient experience improves confidence that concomitant treatment of certain lung, head and neck, or colorectal cancers with cetuximab and an anti-ERBB2 drug may prevent or delay the development of drug resistance. These studies add to other successes for this approach, which has also been used for analysis of other molecular targeted therapies, including EGFR kinase inhibitors. Cetuximab, an antibody directed against the epidermal growth factor receptor, is an effective clinical therapy for patients with colorectal, head and neck, and non–small cell lung cancer, 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 in cell lines, either through ERBB2 amplification or through heregulin up-regulation, leads to persistent extracellular signal–regulated kinase 1/2 signaling and consequently to 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 who exhibit either de novo or acquired resistance to cetuximab-based therapy has 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 cetuximab, represent a rational therapeutic strategy that should be assessed in patients with cetuximab-resistant cancers.

Weekly nab-Paclitaxel in Combination With Carboplatin Versus Solvent-Based Paclitaxel Plus Carboplatin as First-Line Therapy in Patients With Advanced Non–Small-Cell Lung Cancer: Final Results of a Phase III Trial

PURPOSE This phase III trial compared the efficacy and safety of albumin-bound paclitaxel (nab-paclitaxel) plus carboplatin with solvent-based paclitaxel (sb-paclitaxel) plus carboplatin in advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS In all, 1,052 untreated patients with stage IIIB to IV NSCLC were randomly assigned 1:1 to receive 100 mg/m(2) nab-paclitaxel weekly and carboplatin at area under the concentration-time curve (AUC) 6 once every 3 weeks (nab-PC) or 200 mg/m(2) sb-paclitaxel plus carboplatin AUC 6 once every 3 weeks (sb-PC). The primary end point was objective overall response rate (ORR). RESULTS On the basis of independent assessment, nab-PC demonstrated a significantly higher ORR than sb-PC (33% v 25%; response rate ratio, 1.313; 95% CI, 1.082 to 1.593; P = .005) and in patients with squamous histology (41% v 24%; response rate ratio, 1.680; 95% CI, 1.271 to 2.221; P < .001). nab-PC was as effective as sb-PC in patients with nonsquamous histology (ORR, 26% v 25%; P = .808). There was an approximately 10% improvement in progression-free survival (median, 6.3 v 5.8 months; hazard ratio [HR], 0.902; 95% CI, 0.767 to 1.060; P = .214) and overall survival (OS; median, 12.1 v 11.2 months; HR, 0.922; 95% CI, 0.797 to 1.066; P = .271) in the nab-PC arm versus the sb-PC arm, respectively. Patients ≥ 70 years old and those enrolled in North America showed a significantly increased OS with nab-PC versus sb-PC. Significantly less grade ≥ 3 neuropathy, neutropenia, arthralgia, and myalgia occurred in the nab-PC arm, and less thrombocytopenia and anemia occurred in the sb-PC arm. CONCLUSION The administration of nab-PC as first-line therapy in patients with advanced NSCLC was efficacious and resulted in a significantly improved ORR versus sb-PC, achieving the primary end point. nab-PC produced less neuropathy than sb-PC.

Predictive Factors for Interstitial Lung Disease, Antitumor Response, and Survival in Non–Small-Cell Lung Cancer Patients Treated With Gefitinib

PURPOSE Interstitial lung disease (ILD) is a serious adverse effect of gefitinib, but its prevalence and risk factors remain largely unknown. We examined the prevalence of and risk factors for gefitinib-induced ILD associated with practical use of the drug in Japanese with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS Clinical information was retrospectively assembled for NSCLC patients who started gefitinib treatment at affiliated institutions of the West Japan Thoracic Oncology Group between August 31 and December 31, 2002. Medical records of patients who developed pulmonary infiltrates were reviewed by a central committee of extramural experts for identification of patients with gefitinib-induced ILD. Multivariate logistic or Cox regression analysis was performed to identify independent predictive factors for ILD, antitumor response, and survival. RESULTS Seventy cases of and 31 deaths from gefitinib-induced ILD were identified among 1,976 consecutively treated patients at 84 institutions, corresponding to a prevalence of 3.5% and mortality of 1.6%. Gefitinib-induced ILD was significantly associated with male sex, a history of smoking, and coincidence of interstitial pneumonia (odds ratios = 3.10, 4.79, and 2.89, respectively). Predictive factors for response were female sex, no history of smoking, adenocarcinoma histology, metastatic disease, and good performance status (PS), whereas predictive factors for survival were female sex, no history of smoking, adenocarcinoma histology, nonmetastatic disease, good PS, and previous chest surgery. CONCLUSION ILD is a serious adverse effect of gefitinib in the clinical setting that cannot be ignored. However, patient selection based on sex and smoking history can minimize ILD risk and maximize the clinical benefit of gefitinib.

Erlotinib alone or with bevacizumab as first-line therapy in patients with advanced non-squamous non-small-cell lung cancer harbouring EGFR mutations (JO25567): an open-label, randomised, multicentre, phase 2 study

BACKGROUND With use of EGFR tyrosine-kinase inhibitor monotherapy for patients with activating EGFR mutation-positive non-small-cell lung cancer (NSCLC), median progression-free survival has been extended to about 12 months. Nevertheless, new strategies are needed to further extend progression-free survival and overall survival with acceptable toxicity and tolerability for this population. We aimed to compare the efficacy and safety of the combination of erlotinib and bevacizumab compared with erlotinib alone in patients with non-squamous NSCLC with activating EGFR mutation-positive disease. METHODS In this open-label, randomised, multicentre, phase 2 study, patients from 30 centres across Japan with stage IIIB/IV or recurrent non-squamous NSCLC with activating EGFR mutations, Eastern Cooperative Oncology Group performance status 0 or 1, and no previous chemotherapy for advanced disease received erlotinib 150 mg/day plus bevacizumab 15 mg/kg every 3 weeks or erlotinib 150 mg/day monotherapy as a first-line therapy until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival, as determined by an independent review committee. Randomisation was done with a dynamic allocation method, and the analysis used a modified intention-to-treat approach, including all patients who received at least one dose of study treatment and had tumour assessment at least once after randomisation. This study is registered with the Japan Pharmaceutical Information Center, number JapicCTI-111390. FINDINGS Between Feb 21, 2011, and March 5, 2012, 154 patients were enrolled. 77 were randomly assigned to receive erlotinib and bevacizumab and 77 to erlotinib alone, of whom 75 patients in the erlotinib plus bevacizumab group and 77 in the erlotinib alone group were included in the efficacy analyses. Median progression-free survival was 16·0 months (95% CI 13·9-18·1) with erlotinib plus bevacizumab and 9·7 months (5·7-11·1) with erlotinib alone (hazard ratio 0·54, 95% CI 0·36-0·79; log-rank test p=0·0015). The most common grade 3 or worse adverse events were rash (19 [25%] patients in the erlotinib plus bevacizumab group vs 15 [19%] patients in the erlotinib alone group), hypertension (45 [60%] vs eight [10%]), and proteinuria (six [8%] vs none). Serious adverse events occurred at a similar frequency in both groups (18 [24%] patients in the erlotinib plus bevacizumab group and 19 [25%] patients in the erlotinib alone group). INTERPRETATION Erlotinib plus bevacizumab combination could be a new first-line regimen in EGFR mutation-positive NSCLC. Further investigation of the regimen is warranted. FUNDING Chugai Pharmaceutical Co Ltd.

CD44 cleavage induced by a membrane-associated metalloprotease plays a critical role in tumor cell migration

CD44 is a cell surface receptor for hyaluronate, a component of the extracellular matrix (ECM). Although CD44 has been implicated in tumor invasion and metastasis, the molecular mechanisms remain to be elucidated. Here we find that CD44 expressed in cancer cells is cleaved at the membrane-proximal region of the ectodomain and the membrane-bound cleavage product can be detected using an antibody against the cytoplasmic domain of CD44. Furthermore, we report that CD44 cleavage is mediated by a membrane-associated metalloprotease expressed in cancer cells. A tissue inhibitor of metalloproteases-1 (TIMP-1), as well as metalloprotease inhibitors, inhibit CD44 cleavage in the cell-free assay. Contrary, serine protease inhibitors enhance CD44 cleavage, and the enhancement can be prevented by pretreatment with a metalloprotease inhibitor. Thus, CD44 cleavage is regulated by an intricate balance between some proteases and their inhibitors. Interestingly, treatment with the metalloprotease blocker 1,10-phenanthroline, which strongly prevent the CD44 cleavage, suppressed RERF-LC-OK lung cancer cell migration on a hyaluronate substrate, but not on several other substrates. These results suggest that CD44 cleavage plays a critical role in an efficient cell-detachment from a hyaluronate substrate during the cell migration and consequently promotes CD44-mediated cancer cell migration. Our present data indicate that CD44, not only ECM per se, is one of the targets of pericellular proteolysis involved in tumor invasion and metastasis.

Association of PD-L1 overexpression with activating EGFR mutations in surgically resected nonsmall-cell lung cancer

BACKGROUND Recent clinical trials have shown that immune-checkpoint blockade yields a clinical response in a subset of individuals with advanced nonsmall-cell lung cancer (NSCLC). We examined whether the expression of programmed death-ligand 1 (PD-L1) is related to clinicopathologic or prognostic factors in patients with surgically resected NSCLC. PATIENTS AND METHODS The expression of PD-L1 was evaluated by immunohistochemical analysis in 164 specimens of surgically resected NSCLC. Cell surface expression of PD-L1 in NSCLC cell lines was quantified by flow cytometry. RESULTS Expression of PD-L1 in tumor specimens was significantly higher for women than for men, for never smokers than for smokers, and for patients with adenocarcinoma than for those with squamous cell carcinoma. Multivariate analysis revealed that the presence of epidermal growth factor receptor gene (EGFR) mutations and adenocarcinoma histology were significantly associated with increased PD-L1 expression in a manner independent of other factors. Cell surface expression of PD-L1 was also significantly higher in NSCLC cell lines positive for activating EGFR mutations than in those with wild-type EGFR. The EGFR inhibitor erlotinib downregulated PD-L1 expression in the former cell lines but not in the latter, suggesting that PD-L1 expression is increased by EGFR signaling conferred by activating EGFR mutations. A high level of PD-L1 expression in resected tumor tissue was associated with a significantly shorter overall survival for NSCLC patients. CONCLUSIONS High expression of PD-L1 was associated with the presence of EGFR mutations in surgically resected NSCLC and was an independent negative prognostic factor for this disease.

Combined survival analysis of prospective clinical trials of gefitinib for non-small cell lung cancer with EGFR mutations.

Purpose: Somatic mutations of the epidermal growth factor receptor (EGFR) gene are associated with an increased response to gefitinib in patients with non–small cell lung cancer. We have examined the impact of gefitinib on progression-free survival and overall survival in patients with EGFR mutation–positive non–small cell lung cancer. Experimental Design: We searched for all clinical trials that prospectively evaluated the efficacy of gefitinib for advanced non–small cell lung cancer with EGFR mutations in Japan. We did a combined analysis based on individual patient data from the identified trials. Results: Seven eligible trials were identified for a total of 148 non–small cell lung cancer patients with EGFR mutations. The overall response rate to gefitinib was 76.4% [95% confidence interval (95% CI), 69.5-83.2]. The median progression-free survival and overall survival were 9.7 months (95% CI, 8.2-11.1) and 24.3 months (95% CI, 19.8-28.2), respectively. Good performance status and chemotherapy-naïve status were significantly associated with a longer progression-free survival or overall survival. Of the 148 patients, 87 received gefitinib as a first-line therapy, whereas 61 received systemic chemotherapy before gefitinib treatment. The median progression-free survival after the start of first-line therapy was significantly longer in the gefitinib-first group than in the chemotherapy-first group (10.7 versus 6.0 months; P < 0.001), whereas no significant difference in median overall survival was apparent between the two groups (27.7 versus 25.7 months; P = 0.782). Conclusions: Gefitinib monotherapy confers substantial clinical benefit in terms of progression-free survival and overall survival in non–small cell lung cancer patients with EGFR mutations. Randomized trials comparing chemotherapy with gefitinib as a first-line treatment are warranted in such patients.

Randomized, Open-Label, Phase III Study Comparing Irinotecan With Paclitaxel in Patients With Advanced Gastric Cancer Without Severe Peritoneal Metastasis After Failure of Prior Combination Chemotherapy Using Fluoropyrimidine Plus Platinum: WJOG 4007 Trial

PURPOSE This phase III study compared treatment with weekly paclitaxel and biweekly irinotecan in patients with advanced gastric cancer refractory to treatment with fluoropyrimidine plus platinum. PATIENTS AND METHODS Patients were randomly assigned to receive either paclitaxel (80 mg/m(2) on days 1, 8, and 15, every 4 weeks) or irinotecan (150 mg/m(2) on days 1 and 15, every 4 weeks). Primary end point was overall survival (OS), and secondary end points were progression-free survival (PFS), response rate, adverse events, and proportion of patients who received third-line chemotherapy. RESULTS Of 223 patients, 219 were eligible for analysis. Median OS was 9.5 months in 108 patients allocated to the paclitaxel group and 8.4 months in 111 patients allocated to the irinotecan group (hazard ratio [HR], 1.13; 95% CI, 0.86 to 1.49; P = .38). Median PFS was 3.6 months in the paclitaxel group and 2.3 months in the irinotecan group (HR, 1.14; 95% CI, 0.88 to 1.49; P = .33). Response rate was 20.9% in the paclitaxel group and 13.6% in the irinotecan group (P = .24). Common grade 3 to 4 adverse events were neutropenia (paclitaxel group, 28.7%; irinotecan group, 39.1%), anemia (21.3%; 30.0%), and anorexia (7.4%; 17.3%). Treatment-related deaths occurred in two patients (1.8%) in the irinotecan group. Third-line chemotherapy was administered in 97 patients (89.8%) after paclitaxel treatment and in 80 patients (72.1%) after irinotecan treatment (P = .001). CONCLUSION No statistically significant difference was observed between paclitaxel and irinotecan for OS. Both are reasonable second-line treatment options for advanced gastric cancer.

Multicentre prospective phase II trial of gefitinib for advanced non-small cell lung cancer with epidermal growth factor receptor mutations: results of the West Japan Thoracic Oncology Group trial (WJTOG0403).

The purpose of this study was to evaluate the efficacy of gefitinib and the feasibility of screening for epidermal growth factor receptor (EGFR) mutations among select patients with advanced non-small cell lung cancer (NSCLC). Stage IIIB/IV NSCLC, chemotherapy-naive patients or patients with recurrences after up to two prior chemotherapy regimens were eligible. Direct sequencing using DNA from tumour specimens was performed by a central laboratory to detect EGFR mutations. Patients harbouring EGFR mutations received gefitinib. The primary study objective was response; the secondary objectives were toxicity, overall survival (OS), progression-free survival (PFS), 1-year survival (1Y-S) and the disease control rate (DCR). Between March 2005 and January 2006, 118 patients were recruited from 15 institutions and were screened for EGFR mutations, which were detected in 32 patients – 28 of whom were enrolled in the present study. The overall response rate was 75%, the DCR was 96% and the median PFS was 11.5 months. The median OS has not yet been reached, and the 1Y-S was 79%. Thus, gefitinib chemotherapy in patients with advanced NSCLC harbouring EGFR mutations was highly effective. This trial documents the feasibility of performing a multicentre phase II study using a central typing laboratory, demonstrating the benefit to patients of selecting gefitinib treatment based on their EGFR mutation status.

Randomized Phase III Trial of Platinum-Doublet Chemotherapy Followed by Gefitinib Compared With Continued Platinum-Doublet Chemotherapy in Japanese Patients With Advanced Non–Small-Cell Lung Cancer: Results of a West Japan Thoracic Oncology Group Trial (WJTOG0203)

PURPOSE Gefitinib is a small molecule inhibitor of the epidermal growth factor receptor tyrosine kinase. We conducted a phase III trial to evaluate whether gefitinib improves survival as sequential therapy after platinum-doublet chemotherapy in patients with advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS Chemotherapy-naïve patients with advanced stage (IIIB/IV) NSCLC, Eastern Cooperative Oncology Group performance status of 0 to 1, and adequate organ function were randomly assigned to either platinum-doublet chemotherapy up to six cycles (arm A) or platinum-doublet chemotherapy for three cycles followed by gefitinib 250 mg orally once daily, until disease progression (arm B). Patients were stratified by disease stage, sex, histology, and chemotherapy regimens. The primary end point was overall survival; secondary end points included progression-free survival, tumor response, safety, and quality of life. Results Between March 2003 and May 2005, 604 patients were randomly assigned. There was a statistically significant improvement in progression-free survival in arm B (hazard ratio [HR], 0.68; 95% CI, 0.57 to 0.80; P < .001); however, overall survival results did not reach statistical significance (HR, 0.86; 95% CI, 0.72 to 1.03; P = .11). In an exploratory subset analysis of overall survival by histologic group, patients in arm B with adenocarcinoma did significantly better than patients in arm A with adenocarcinoma (n = 467; HR, 0.79; 95% CI, 0.65 to 0.98; P = .03). CONCLUSION This trial failed to meet the primary end point of OS in patients with NSCLC. The exploratory subset analyses demonstrate a possible survival prolongation for sequential therapy of gefitinib, especially for patients with adenocarcinoma.