Sintilimab in Patients with Previously Treated Metastatic Neuroendocrine Neoplasms.

BACKGROUND: Neuroendocrine neoplasms (NENs) are a group of diseases that show high heterogeneity but have limited treatment options. This phase I study evaluated the safety and efficacy of sintilimab, anti-PD-1 monoclonal antibody, in treating advanced NENs. METHODS: We prospectively enrolled patients pathologically diagnosed with NENs after standard treatment failure. Neuroendocrine neoplasms were classified into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine cancers (NECs). Every patient received sintilimab, and response was assessed every 9 weeks. RESULTS: Twenty-four patients with a median age of 57.0 years were enrolled from November 2016 to 2017. The median Ki-67 index was 60%. Five patients had NET, 1 had NET G3, 17 had NEC, and 1 had mixed adenocarcinoma-neuroendocrine carcinoma. The most common primary tumor sites were the pancreas and gastrointestinal tract in 7 and 10 patients, respectively. In phase Ia trial, 2 patients received sintilimab 1 mg/kg every 2 weeks, one received 3 mg/kg every 2 weeks, and 21 patients enrolled in the phase Ib trial received 200 mg every 3 weeks. The objective response rate was 20.8% in all enrolled patients and 27.8% in NEC patients. The median progression-free survival was 2.2 and 2.1 months in patients with NET and NEC, respectively. The median OS was not applicable (NA) and 10.8 months (95% CI, 4.3, NA) with NET and NEC, respectively. The duration of response (DOR) was not reached, with a median follow-up time of 20.7 months. Treatment-related adverse events (TRAE) occurred in 17 (70.8%) patients. The most frequent TRAE was thyroid dysfunction (41.7%), and a grade 3 pulmonary infection occurred in 1 patient. The programmed cell death 1-ligand 1 (PD-L1)-positive (tumor proportion score ≥1%) rate was 18.8% (3 out of 16) and the expression of PD-L1 did not correlate with response. CONCLUSION: Sintilimab was well-tolerated and showed encouraging response in NECs. CLINICALTRIALS.GOV IDENTIFIER: NCT02937116.

Post-radiation circulating tumor DNA as a prognostic factor in locally advanced esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is a highly malignant and deadly tumor. Radiation therapy is one of the primary treatments for locally advanced ESCC. However, the biomarkers for prognosis of definitive radiation remain undefined. Peripheral blood circulating tumor (ct)DNA provides information of tumor genetic alterations and has been confirmed as a potential non-invasive biomarker for several types of cancer. The present study investigated the clinical implications of ctDNA detection in patients with ESCC and receiving definitive radiation therapy. Patients with locally advanced ESCC were retrospectively recruited. Plasma samples were collected before, during and following radiation therapy. Next-generation sequencing was performed to identify somatic mutations in 180 genes. A total of 69 baseline and post-radiation plasma samples were collected from 25 patients. A total of 59 non-silent single nucleotide variants were present in 33 genes. All pre-radiation and 58.3% (14/24) of post-radiation samples had at least one mutation. Patients with lymph node metastases (LNM) exhibited a higher number of pre-radiation mutations compared with those without LNM. The variables, progression-free survival (PFS) and overall survival (OS) of the patients with one baseline mutation were not significantly different compared with that in patients with more than one baseline mutation. Patients with initial ctDNA-positive post-radiation samples exhibited significantly reduced PFS (P=0.047) and OS (P=0.005) compared with that in patients with ctDNA-negative samples. The post-radiation plasma ctDNA status was an independent prognostic factor from univariate and multivariate analyses. Dynamic monitoring of ctDNA during follow-up was examined. The results indicated that ctDNA was a predictive and prognostic marker in patients with ESCC and receiving definitive radiation therapy, which may guide subsequent treatment.

Aspergillus niger bloodstream infection in gastric cancer after common hepatic artery embolization: A case report.

The present case study reported on a 62-year-old male patient with gastric cancer-associated Aspergillus (A.) niger bloodstream infection. The patient presented with massive hemorrhage in the gastrointestinal tract 3 months after total gastrectomy for gastric cancer. Conservative treatment consisting of blood transfusion to supplement blood volume loss was ineffective. Digital subtraction angiography indicated gastroduodenal artery bleeding. The first attempt of performing arterial embolization using gelatin sponges failed, while the second attempt of performing common hepatic artery embolization using gelatin sponges and micro-coil springs stopped the bleeding. Four weeks after angiography, the patient presented with the complication of A. niger bloodstream infection, which was cured using intravenous and oral voriconazole. Clinicians should be aware of the possibility of A. niger bloodstream infection after invasive operations in immunocompromised patients and apply timely antifungal treatment.

PIK3CA Mutations Contribute to Acquired Cetuximab Resistance in Patients with Metastatic Colorectal Cancer.

Purpose: Mutations in KRAS are considered to be the main drivers of acquired resistance to epidermal growth factor receptor (EGFR) blockade in patients with metastatic colorectal cancer (mCRC). However, the potential role of other genes downstream of the EGFR signaling pathway in conferring acquired resistance has not been extensively investigated.Experimental Design: Using circulating tumor DNA (ctDNA) from patients with mCRC and with acquired cetuximab resistance, we developed a targeted amplicon ultra-deep sequencing method to screen for low-abundance somatic mutations in a panel of genes that encode components of the EGFR signaling pathway. Mutations with significantly increased variant frequencies upon disease progression were selected by using quartile analysis. The functional consequences of the identified mutations were validated in cultured cells.Results: We analyzed 32 patients with acquired cetuximab resistance in a development cohort. Of them, seven (22%) carried five novel PIK3CA mutations, whereas eight (25%) carried previously reported KRAS mutations. Functional studies showed that novel PIK3CA mutations (all in exon 19; p.K944N, p.F930S, p.V955G, p.V955I, and p.K966E) promote cell viability in the presence of cetuximab. Only one novel PIK3CA mutation (p.K944N) was verified in one of the 27 patients with acquired resistance in a validation cohort, simultaneous KRAS and PIK3CA hotspot mutations were detected in two patients. Among the above 59 acquired resistance patients, those with PIK3CA or RAS mutations detected in ctDNA showed a pronounced decrease in progression-free survival than patients with no mutation.Conclusions: The PIK3CA mutations may potentially contribute to acquired cetuximab resistance in patients with mCRC. Clin Cancer Res; 23(16); 4602-16. ©2017 AACR.

Clinicopathological observation of primary lung enteric adenocarcinoma and its response to chemotherapy: A case report and review of the literature.

Primary lung enteric adenocarcinoma is a rare type of invasive lung carcinoma. Its morphology and immunohistochemistry are those of colorectal carcinoma, but there is no associated primary colorectal carcinoma. The present study describes the case of a 53-year-old female who presented with an irritating cough and a mass around the right sternoclavicular joint. Comprehensive evaluation revealed involvement of the mediastinum, lungs, right sternoclavicular joint and right kidney. Biopsies from the mediastinal and right sternoclavicular joint tumors showed features of adenocarcinoma. Immunohistochemistry was positive for cytokeratin (CK)20 and caudal type homeobox transcription factor 2, and negative for CK7, thyroid transcription factor-1 and napsin A. Genotypic analysis identified the expression of wild-type epidermal growth factor receptor, Kirsten rat sarcoma viral oncogene homolog, serine/threonine-protein kinase B-Raf and UDP-glucuronosyltransferase 1-1. There was no expression of echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase and a moderate expression of excision repair cross-complementation group 1, ribonucleoside-diphosphate reductase large subunit and tubulin ß-3 chain. A strong expression of thymidylate synthase and 677TC genotype expression of methylenetetrahydrofolate reductase was observed. Gastroscopy, enteroscopy, colorectal colonoscopy and positron emission tomography-computed tomography failed to find evidence of a gastrointestinal malignancy and primary lung enteric adenocarcinoma was diagnosed. The presence of multiple metastases did not permit curative surgery. The patient was treated with 3 monthly cycles of the XELOX chemotherapy regimen; the response was poor with progression of supraclavicular lesions. Treatment was switched to the TP regimen for 4 monthly cycles, which resulted in a significant reduction in the size of the lung lesions; however, the supraclavicular lesion responded poorly to the treatment. The patient then received 2 cycles of the FOLFIRI regimen; however, the lung and right supraclavicular lesions progressed, causing increased right upper limb pain. The pain was alleviated by palliative surgery. Following surgery, the DP regimen was employed. Follow-up of the patient remains ongoing. The present findings suggest that the early diagnosis and treatment of primary lung enteric adenocarcinoma is likely to improve patient outcome.

Diffuse alveolar hemorrhage after erlotinib combined with concurrent chemoradiotherapy in a patient with esophageal carcinoma.

Diffuse alveolar hemorrhage (DAH) is a life-threatening clinical pathologic syndrome caused by a variety of diseases. We report a case of DAH related to combination therapy of chemoradiotherapy and erlotinib. As to know, DAH following chemoradiotherapy was only reported among hematopoietic stem cell transplant recipients with hematologic malignancies till now. DAH associated with chemoradiotherapy for oesophageal carcinoma has not been reported. This is the first DAH report on erlotinib-combined chemoradiotherapy for esophageal cancer. The authors believe epidermal growth factor receptor tyrosine kinase inhibitor erlotinib increased the lung injury. Molecular targeted drugs are gradually applied to be combined with chemoradiation, whether this combination will cause the increase of serious adverse reactions need further study. This case can provide certain reference for erlotinib in the treatment. Meanwhile, after long term hormone therapy for DAH, the patient was diagnosed with pneumocystis carinii pneumonia. It reminds us to attach importance to the immunosuppressive diseases after long-term hormone treatment.

[Correlation analysis between abundance of K-ras mutation in plasma free DNA and its correlation with clinical outcome and prognosis in patients with metastatic colorectal cancer].

OBJECTIVE: To detect K-ras gene mutations in plasma free DNA by peptide nucleic acid clamp PCR assay (PNA-PCR) and nested primer PCR, and to analyze the correlation between K-ras mutations and prognosis in patients with metastatic colorectal cancer (mCRC). METHODS: Peripheral blood was collected and free DNA was extracted from plasma in 106 patients with mCRC. Nested primer PCR and PNA-PCR were used to detect K-ras gene mutation in the plasma free DNA. The patients were divided into three groups by K-ras status: wild-type group (wild-type determined by both methods), low mutation group (mutation by PNA-PCR method, wild-type by nested primer PCR method) and high mutation group (mutation by two methods). The correlation between K-ras mutations and prognosis was analyzed. RESULTS: The mutation rate of K-ras in tumor tissues of the 106 patients was 40.6%. The Mutation rate of K-ras in plasma free DNA detected by PNA-PCR was 31.1%, significantly higher than that of 15.1% detected by nested primer PCR (P = 0.006). The consistent rate of the K-ras status in plasma free DNA detected by PNA-PCR and that in tumor tissue detected by traditional method was up to 83.0%. The median overall survival (OS) of patients of the wild type, low mutation and high mutation groups was 23.5 months, 17.3 months and 13.9 months, respectively (P = 0.002). The median progression-free survival (PFS) of the K-ras wild-type, low mutation and high mutation groups with first-line chemotherapy was 6.8 months, 6.1 months and 3.2 months, respectively (P = 0.002), and the median OS of them were 23.0 months, 15.5 months and 13.9 months, respectively (P = 0.036). The overall response rate (ORR) was improved in the K-ras wide-type patients who received cetuximab combined with chemotherapy as first-line therapy (75.0% vs. 23.4%, P = 0.058). Cetuximab combined with in second-line therapy chemotherapy led to a significant improvement in disease control rate (DCR) ( 100% vs. 35.7%, P < 0.001) as compared with those of chemotherapy alone. COX regression model showed that K-ras status detected by PNA-PCR, ECOG PS, number of surgery and initially metastatic site were independent factors for prognosis. CONCLUSIONS: PNA-PCR for the detection of K-ras mutation in plasma free DNA can be used to substitute the traditional method for detection of K-ras mutation in tumor tissues. The abundance of K-ras mutation in plasma free DNA is an independent prognostic factor for patients with metastatic colorectal cancer.

[Analysis of therapeutic effect and prognosis in patients with metastatic colorectal cancer and different K-ras status].

OBJECTIVE: To evaluate the correlation of clinical effect and prognosis between patients with metastatic colorectal cancer (mCRC) and different K-ras status. METHODS: The clinical characteristics, chemotherapeutic regimens and survival of 153 mCRC patients with different K-ras status were analyzed retrospectively. RESULTS: The median overall survival (OS) in patients without K-ras mutation were 31.7 months, significantly longer than 21.3 months in the patients with K-ras mutation (P = 0.037). The median progression-free survival (PFS) and OS in patients who received chemotherapy followed by anti-EGFR antibody treatment were 11.5 and 39.3 months, respectively, significantly longer as compared with the PFS and OS in those received chemotherapy in combination with anti-EGFR antibody concomitantly (5.7, P = 0.02, and 28.7 months, P = 0.034, respectively). CONCLUSIONS: K-ras status is a prognostic biomarker for mCRC patients treated with anti-EGFR antibody. The combination settings of anti-EGFR in combination with chemotherapy may improve survival of mCRC patients with wild-type K-ras status.

Expression and prognostic value of VEGFR-2, PDGFR-ß, and c-Met in advanced hepatocellular carcinoma.

BACKGROUND: We explore the clinical and prognostic significance of expression of vascular endothelial growth factor receptor (VEGFR)-2, platelet-derived growth factor receptor (PDGFR)-ß, and c-Met in patients with hepatocellular carcinoma (HCC). METHODS: The expression of VEGFR-2, PDGFR-ß, and c-Met were determined by immunohistochemical examination of the tissues of 93 HCC patients. The relationships of these markers with clinicopathological factors and prognosis were then analyzed. RESULTS: High expression of VEGFR-2, PDGFR-ß, and c-Met was found in 86%, 19.4%, and 80.6% of patients, respectively. Expression of VEGFR-2 correlated with gender (P = 0.044), hepatitis B surface antigen positivity (P = 0.024), degree of tumor differentiation (P = 0.023), and hepatic cirrhosis (P = 0.026). Expression of PDGFR-ß correlated with alpha-fetoprotein level (P = 0.029), tumor size (P = 0.033), and hepatic cirrhosis (P = 0.023). No significant correlations were identified between expression of c-Met and clinicopathological factors. Expression of PDGFR-ß correlated with overall survival (P = 0.046) and expression of c-Met correlated with progression-free survival (P = 0.01). CONCLUSIONS: We found that in patients with HCC, high expression of VEGFR-2 correlates with chronic hepatitis B virus infection and hepatic cirrhosis. High expression of PDGFR-ß is a predictor of poor prognosis. High expression of C-Met may predict therapeutic effectiveness of sorafenib in HCC patients.

[Clinical analysis of the current treatment status of gastric cancer in 636 patients].

OBJECTIVE: To evaluate the current clinical treatment status of gastric cancer in China. METHODS: A retrospective analysis of clinicopathological characteristics of 636 patients with gastric cancer was conducted. Tumor response was evaluated using RECIST version 1.1 criteria. RESULTS: Six hundred and thirty-six patients were included in this retrospective cohort: 479 men and 157 women. The median age was 57 years (14 to 86). The tumor site was: proximal (41.4%), distal (46.4%) or unknown (12.2%). The histology was: adenocarcinoma (85.8%), signet ring cell carcinoma (6.9%), or other and unknown (7.2%). The differentiation of the adenocarcinomas was: well differentiated (31.0%), moderately differentiated (13.4%), poorly differentiated (37.0%), or unknown (18.7%). The pTNM stage was: 0 (0.3%), I (3.6%), II (10.1%), III (36.8%), IV (45.6%), or unknown (3.6%). In 284 patients who underwent radical resection, the ratio of examined ten and/or more lymph nodes was higher in hospitals at or above provincial level than in hospitals at regional level (57.9% vs. 39.6%, P = 0.009). The disease-free survival was longer (21.7 m vs. 14.6 m, P = 0.005), and the overall survival was longer too (52.9 m vs. 33.8 m, P = 0.040). In 205 patients who received adjuvant chemotherapy, the ratio of administered six and/or more cycles chemotherapy was 42.1% vs. 35.2% (P = 0.318), and the disease-free survival was 22.7 m vs. 16.3 m (P = 0.005) between hospitals at or above provincial level and hospitals at regional level. In 387 patients with metastatic or unresectable gastric cancer who received palliative chemotherapy, the overall survival was 11.1 m (95%CI 9.9 - 12.3 m). Among them, 198 patients received second and/or more line chemotherapy, and the overall survival was longer (12.5 m vs. 7.7 m, P < 0.001). Except a longer progression-free survival (10.2 m, P < 0.05) and a longer overall survival (16.9 m, P < 0.05) were corresponded with the regimen containing trastuzumab, no other significant difference was observed among regimens in first line chemotherapy. CONCLUSION: Chinese doctors working in different level hospitals have a different understanding of the treatment standard of gastric cancer, which resulted in different outcomes.

[HER-2 expression in advanced gastric cancer and its correlation with clinical features, outcome and prognosis].

OBJECTIVE: To assess the HER-2 status in Chinese advanced gastric cancer patients and explore its correlation with clinical features, treatment response and prognosis. METHODS: A total of 107 patients with advanced gastric cancer treated in our hospital from December 2005 to November 2008 were included in this retrospective analysis. HER-2 status was determined by immunohistochemisty (IHC) and/or fluorescence in situ hybridization (FISH). The correlations of HER-2 status with tumor location, pathology, treatment response and prognosis were analyzed and the efficacy of different chemottherapy regimens was compared. RESULTS: The overall positive rate of HER-2 expression was 14.7% (15/102). The HER-2 status was detected by both methods in 102 patients, and the concordance of the two methods was 66.5%. The tumor site distribution was gastroesophageal junction (GEJ) 28.0%, proximal stomach 19.4%, gastric corpus 16.1%, antrum 26.9% and whole stomach 9.7%, respectively. There was no significant difference of HER-2 status among different tumor sites (P = 0.726), and no significant correlation between HER-2 expression and differentiation (P = 0.110). Among the evaluable 51 patients treated by first-line chemotherapy, the total objective effective rate was 23.5%. The median time-to-progression was 7.47 months, and median overall survival time was 11.07 months. The effective rate was 43.8% in patients who received XP regimen chemotherapy (cisplatin + capecitabine), significantly higher than the 14.3% in patients treated with other regimens (P = 0.033). Their overall survival was 14.17 months and 9.53 months, respectively (P = 0.059). The TTP was 6.63 months in HER-2 positive patients and 7.47 months in HER-2 negative patients, with a non-significant difference (P = 0.510). However, there was a improving tendency in the efficacy and OS, showing a effective rate of 45.5% and 17.5% (P = 0.102) and OS of 14.17 months and 10.63 months, respectively (P = 0.205). CONCLUSIONS: HER-2-positivity rate in Chinese patients with advanced gastric cancer is similar to those reported in the literature. Along with the increasing use of targeted therapy and targeted agents, the efficacy and survival of gastric cancer patients is improving. HER-2-positive patients may benefit from it.

[Evaluation of bevacizumab combined with irinotecan-based regimen as the first-line treatment for patients with metastatic colorectal cancer].

OBJECTIVE: To assess the efficacy and safety of bevacizumab plus irinotecan-based regimen for the first line treatment in metastatic colorectal cancer (mCRC) patients, and to investigate the correlation between serum tumor markers including CEA and CA19-9 and response as well as prognosis. METHODS: From May 2007 to July 2008, 67 previously untreated mCRC patients received treatment of IFL (n = 25), IFL plus Bevacizumab (n = 20) or FOLFIRI (n = 22). The treatment continued until disease progression or unacceptable toxicity. The data were retrospectively analyzed. RESULTS: All patients were evaluable for response, survival and toxicity analysis. The objective response rate of IFL, IFL plus Bevacizumab or FOLFIRI regimen groups was 16.0% (4/25), 35.0% (7/20) and 18.2% (4/22), respectively (χ(2) = 6.026, P = 0.049). The median progression-free survival (PFS) of IFL plus bevacizumab group was 7.5 months, significantly improved as compared with 3.7 months in the IFL group and 4 months in FOLFIRI group (χ(2) = 11.97, P = 0.003). Of all 67 cases, the one-year survival rate was 47.0%, two-year survival rate was 27.0%, and the median overall survival (OS) was 13.0 months, with no significant difference among the three treatment groups (χ(2) = 3.42, P = 0.18). The serum CEA and CA19-9 levels were decreased after treatment, but with no significant difference among the three groups (P > 0.05). The common toxicity profiles of IFL and FOLFIRI regimens were diarrhea and neutropenia, while the toxicity related to bevacizumab was consistent with that documented in previous literature, such as hypertension, hemorrhage, cardiac toxicity and delayed wound healing. CONCLUSION: The addition of bevacizumab to irinotecan-based regimen significantly improves the response rate and PFS in first-line treatment for patients with mCRC and its toxicity is well tolerated.

[Cytotoxic effect of epidermal growth factor receptor tyrosine kinase inhibitor ZD1839 in combination with oxaliplatin on lung cancer cell line A549].

BACKGROUND & OBJECTIVE: ZD1839, a selective epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), has clinical antitumor activity, but its efficacy is low. This study was to assess the effects of ZD1839 in combination with oxaliplatin on lung adenocarcinoma cell line A549, and to provide pre-clinical evidence for optimizing the schedule of oxaliplatin combined with ZD1839. METHODS: Chou and Talalay method was used to analyze the combination effects of sequencing ZD1839 and oxaliplatin on A549 cells. Cell cycle distribution and cell apoptosis were analyzed by flow cytometry. The effects of oxaliplatin combined with ZD1839 on the proliferation of A549 cells in nude mice were also evaluated. RESULTS: Sequential oxaliplatin followed by ZD1839 produced synergistic effect, with a combination index (CI) of 0.51+/-0.01. In contrast, ZD1839 followed by oxaliplatin exhibited antagonist effect, with a CI of 1.56+/-0.03. Compared with other sequences, oxaliplatin followed by ZD1839 induced more cells being arrested in G(2/M) phase (37.9%, P<0.05); the apoptosis rate was 22.3%. The inhibition rate of tumor growth in nude mice was 58.9% when treated with oxaliplatin followed by ZD1839, 52.4% when treated with oxaliplatin and ZD1839 for 24 h and followed by ZD1839 for additional 48 h, and 30.6% when treated with ZD1839 followed by oxaliplatin. CONCLUSION: Sequential oxaliplatin followed by ZD1839 has the maximal inhibitory effect on the proliferation of A549 cells.

Phase II trial of sequential gefitinib after minor response or partial response to chemotherapy in Chinese patients with advanced non-small-cell lung cancer.

BACKGROUND: Basic research of gefitinib (Iressa, ZD1839) has demonstrated the combination effects of gefitinib and chemotherapy were sequence-dependent. To evaluate the efficacy of sequential administration of gefitinib following a minor response or partial response to two to three cycles of chemotherapy, a phase II clinical trial was done in Chinese patients with advanced non-small-cell lung cancer (NSCLC). METHODS: Thirty-three consecutive patients with advanced NSCLC that had been pretreated with at least one chemotherapeutic regimen and were responding to chemotherapy following 2 to 3 cycles of treatment, entered the trial from May 2004 to February 2006. Patients received gefitinib at an oral dose of 250 mg once daily for 4 weeks. RESULTS: Thirty-three patients were evaluable for response and toxicity. The objective response rate was 24.2% (8 of 33) (95% CI, 11% to 42%). The symptom improvement rate was 54.5% (18 of 33) (95% CI, 41% to 69%). The median duration of response was 7 months (95%CI, 4.0 to 13.2 months). The median time to disease progression (TTP) was 6.5 months (95%CI, 0.7 to 16.6 months). The median overall survival time (OS) was 9.8 months (range, 2.1 to 18.0 months), and the actuarial 1-year survival was 36.4%. Toxicity was relatively mild and included only one patient (3.0%) with grade 4 diarrhea, 1 (3.0%) with grade 3 rash, 1 (3.0%) with grade 3 nausea, and 1 with grade 3 vomiting (3.0%). CONCLUSION: Preliminary results suggest that sequential administration of gefitinib following a response to chemotherapy may be beneficial for Chinese patients with advanced NSCLC. Further randomized clinical trials are needed.

[Experimental study of effect of epidermal growth factor receptor tyrosine kinase inhibitor ZD1839 in combination with irinotecan].

OBJECTIVE: To assess the optimal regimen and its mechanism of ZD1839 in combination with SN38, the active metabolite of irinotecan (CPT-11), in the colon cancer cell lines HT-29 and LoVo. METHODS: Chou and Talalay method was used to analyze the combination effects of sequencing of ZD1839 and SN38. Western blotting and immunoprecipitation were used to determine the effects of ZD1839 and/or SN38 on their targeted enzymes and downstream markers. Apoptosis was assayed by analyzing histone-associated DNA fragment. RESULTS: Sequential SN38 followed by ZD1839 produced a synergistic effect. In contrast, SN38 following ZD1839 exhibited an antagonist effect. SN38 markedly inhibited topoisomerase I (Topo-I) activity. ZD1839 did not alter epidermal growth factor receptor (EGFR) expression, but resulted in a complete inhibition of EGFR phosphorylation. Sequential ZD1839 followed by SN38 did not show any enhanced inhibition effect on Topo-I activity, phosphorylation of EGFR and one of its downstream markers MAPK. However, simultaneous SN38 plus ZD1839, and sequential SN38 followed by ZD1839 administrations showed modest inhibition effect on EGFR's another downstream marker AKT. The combination schedules also showed prominent influence on cell cycle distribution. ZD1839 maintained SN38-induced DNA damage and apoptosis. CONCLUSION: Sequential SN38 followed by ZD1839 may be a favorable combination schedule.