Role of early serial change in serum carcinoembryonic antigen levels as a predictive marker for radiological response to gefitinib in Japanese patients with non-small cell lung cancer

BACKGROUND

There have been no reports evaluating the utility of monitoring early change in serum carcinoembryonic antigen (CEA) level as a predictor for subsequent radiological response to gefitinib in patients with non-small cell lung cancer. In this report, we investigated its role using the data from 110 non-small cell lung cancer (NSCLC) patients.

METHODS

The daily rate of CEA change was defined as: (M0-Mx)/Dx/M0x100(%), using the baseline level (M0), the level on day X (Mx), and the number of days from day 1 to day X (Dx).

RESULTS

The daily rate of CEA change until confirmation of an objective response was significantly higher in patients with an objective response or stable disease than progressive disease (PD) patients (p < 0.0001). Receiver operating characteristic analysis revealed that a cut-off level of 0.58% increase most accurately reflected tumor shrinkage, with sensitivity and specificity for disease control of 89.1% and 73.3%, respectively. In 41 (37%) patients, CEA was reassessed within the first two weeks after day 1. The daily rate of CEA change in this early phase tended to vary with the response (p = 0.0975), and reflected disease control less precisely, with sensitivity and specificity of 82.1% and 40.0%, respectively when a cut-off of 0.58% increase was used.

CONCLUSION

The extent of CEA change until confirmation of an objective response correlated significantly with tumor burden. Monitoring an early CEA change, however, did not seem to be useful for detection of PD patients because of the low specificity. Considering the relatively high sensitivity, this model might be helpful for detecting those in whom subsequent disease control is likely.

Combination of SN-38 with gefitinib or imatinib overcomes SN-38-resistant small-cell lung cancer cells

Irinotecan is one of the effective anticancer agents for small-cell lung cancer (SCLC) and 7-ethyl-10-hydroxy-campthothecin (SN-38) is an active metabolite of irinotecan. Gefitinib and imatinib are tyrosine kinase inhibitors which have clinical activities in several malignancies and they are also potent inhibitors of breast cancer resistance protein (BCRP) transporter, which confers the resistance of topoisomerase I inhibitors including SN-38 and topotecan. The cytotoxicity of SN-38, gefitinib and imatinib for the SN-38-resistant cells (SBC-3/SN-38) from human SCLC cells, SBC-3, was evaluated using AlamarBlue assay. The drug concentration required to inhibit the growth of tumor cells by 50% (IC50) for 96-h exposure was used to evaluate the cytotoxicity. BCRP expression was determined by Western blotting and immunofluorescence staining. Intracellular topotecan accumulation was evaluated by flow cytometry. No differences were observed in the IC50 values (mean +/- SD) of the tyrosine kinase inhibitors between the SBC-3 cells and the SBC-3/SN-38 cells: 15+/-1.6 and 12+/-2.8 microM of gefitinib, respectively; 15+/-0.51 and 14+/-3.9 microM of imatinib, respectively. The SBC-3/SN-38 was 9.5-fold more resistant to SN-38 than the parental SBC-3. The SBC-3/SN-38 restored sensitivity to SN-38 when combined with 8 microM gefitinib or 8 microM imatinib, even though the IC50 values of SN-38 combined with gefitinib or imatinib in the SBC-3 cells did not change. BCRP was equally overexpressed in the SBC-3/SN-38 with and without gefitinib or imatinib. In addition, the BCRP expression on the SBC-3/SN-38 cell membrane with and without gefitinib seemed to be equal. Gefitinib increased intracellular accumulation of topotecan in the SBC-3/SN-38 cells. Gefitinib or imatinib reversed SN-38-resistance in these SCLC cells, possibly due to intracellular accumulation of SN-38 without any change in BCRP quantity. Irinotecan with gefitinib or imatinib might be effective for SCLC refractory to irinotecan.

The impact of epidermal growth factor receptor gene status on gefitinib-treated Japanese patients with non-small-cell lung cancer

We investigated the relationships between genetic factors and clinical outcome in Japanese non-small-cell lung cancer (NSCLC) patients treated with gefitinib. Ninety-eight NSCLC patients who had been treated with gefitinib, were screened for mutations in epidermal growth factor receptor (EGFR) exons 18-21, KRAS exon2, and polymorphisms including the CA simple sequence repeat in intron1 (CA-SSR1) and single nucleotide polymorphisms in the promoter region (-216G/T and -191C/A), using a PCR-based assay and direct sequencing. The EGFR copy number status was also evaluated using a fluorescence in situ hybridization assay. EGFR and KRAS mutations were found in 38 (38.8%) and 8 (8.2%) of the 98 patients, respectively. A high EGFR copy number status was identified in 31 (41.3%) of the 75 assessable patients. Drug-sensitive EGFR mutations limited to exon19 deletions and L858R were independent predictive factors of a stronger sensitivity to gefitinib (p = 0.0002), the overall survival (OS) (p = 0.0036), and prolonged progression-free survival (PFS) (p < 0.0001). The EGFR copy number status was not related to a sensitivity to gefitinib and prolonged OS and PFS. Regarding polymorphisms, patients with a short CA-SSR1 showed a prolonged OS as compared with those with a long length in patients with a drug-sensitive EGFR mutation, although this difference was not significant (p = 0.13). Thus, drug-sensitive EGFR mutations predict a favorable clinical outcome and a high EGFR copy number may not be related to clinical benefits in gefitinib-treated Japanese patients with NSCLC. Our findings also suggest that the CA-SSR1 length may influence the clinical outcome in patients with a drug-sensitive EGFR mutation.

A phase II trial of cisplatin and irinotecan alternating with doxorubicin, cyclophosphamide and etoposide in previously untreated patients with extensive-disease small-cell lung cancer

PURPOSE

The aim of this trial was to investigate the efficacy and safety of cisplatin (P) and irinotecan (I) (PI) alternating with doxorubicin (A), cyclophosphamide (C) and etoposide (E) (ACE) in patients with extensive-disease small-cell lung cancer (ED-SCLC).

PATIENTS AND METHODS

Patients with previously untreated ED-SCLC were enrolled in this trial. In the first, third and fifth cycles, PI (P: 60 mg/m(2) on day 1; I: 60 mg/m(2)/day on days 1, 8 and 15) was administered, whereas ACE (A: 50 mg/m(2) on day 1; C: 750 mg/m(2) on day 1; E 80 mg/m(2)/day on days 1-3) was given in the second, fourth and sixth cycles. Each cycle was repeated every 4 weeks. At the end of six cycles, patients who had obtained a complete response were given prophylactic cranial irradiation.

RESULTS

In total, 28 patients were enrolled, of whom 27 were assessable for efficacy and safety. Objective responses, including 4 (15%) complete responses, were observed in 25 patients (93%). Median survival time was 12.9 months. The principal toxicity was myelosuppression; grade 4 neutropenia and thrombocytopenia were observed in 89 and 4%, respectively. Febrile neutropenia occurred in 30% of patients. Diarrhea was mild (grade 3-4; 4%). All toxicities were reversible and there were no treatment-related deaths. The mean percentage of the delivered doses, relative to the projected doses, of PI and ACE were 84.6 and 91.1%, respectively.

CONCLUSIONS

These results indicate the PI-ACE regimen to have promising activity against ED-SCLC with moderate toxicities.

Serum level of arginine-vasopressin influences the prognosis of extensive-disease small-cell lung cancer

PURPOSE

The purpose of this study is to elucidate the influence of serum arginine-vasopressin (AVP) level on prognosis of extensive-disease small-cell lung cancer (ED-SCLC).

METHODS

We retrospectively investigated the clinical records of 163 patients with ED-SCLC, who were admitted to Okayama University Hospital or National Shikoku Cancer Center Hospital. The influence of 14 pretreatment variables on survival was analyzed.

RESULTS

In a multivariate analysis of 163 patients, elevation of serum LDH level (P = 0.028) and poor performance status (PS > or = 2, P = 0.002) were independent poor prognostic factors. In 34 patients whose serum AVP levels were available, high serum AVP level was related to the poor prognosis (P < 0.001). The serum-sodium level did not affect the survival. Median serum level of osmotic pressure in 34 patients was normal (284.9 mOsm/kg), although, serum osmotic pressure was low in four of six patients with high serum AVP level. In all patients with high serum AVP level, serum LDH level was elevated.

CONCLUSIONS

The data from the current study suggested that serum LDH level and PS were the poor prognostic factors for ED-SCLC. But we additionally identified the prognostic significance of serum AVP level, which may be a more useful factor than serum-sodium level.

Being overweight influences the development of hepatic dysfunction in Japanese patients with non-small-cell lung cancer undergoing cytotoxic chemotherapy

PURPOSE

The aim of this study was to identify risk factors for hepatic dysfunction during cytotoxic chemotherapy in Japanese patients with non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

We retrospectively reviewed the medical records of patients with NSCLC who received cytotoxic chemotherapy at Okayama University Hospital between January 2003 and March 2006. "Overweight" was defined as a body mass index (BMI) of 25 or more, according to the World Health Organization (WHO) criteria. We investigated the incidence and pattern of hepatic dysfunction during chemotherapy and evaluated the possible associations between hepatic dysfunction and several clinical factors, including BMI.

RESULTS

Of the 155 Japanese patients enrolled in this study, 19 (12%) were overweight. Grade 2 or worse hepatic dysfunction was observed in 5 of the 19 overweight patients (26%) but in only 13 of the 136 non-overweight patients (10%). A multivariate analysis demonstrated that a higher BMI significantly increased the risk of grade 2 or worse hepatic dysfunction after the initiation of cytotoxic chemotherapy (odds ratio=4.04, 95% confidence intervals: 1.13-14.5, p=0.032).

CONCLUSION

Our data suggest that being overweight can influence the development of hepatic dysfunction in Japanese patients receiving cytotoxic chemotherapy for the treatment of NSCLC, although further investigation is required.

Gefitinib induces premature senescence in non-small cell lung cancer cells with or without EGFR gene mutation

Despite its tremendous antitumor effect in a subset of patients with non-small cell lung cancer (NSCLC), the exact mechanism of gefitinib-induced cell death has not been fully determined. In this study, forms of cell death in various NSCLC cell lines after gefitinib exposure was analyzed to elucidate the cell death mechanism of gefitinib. Though higher concentration of gefitinib (10 microM) induced extensive apoptosis in two cell lines (EGFR-mutated PC-9 cells and EGFR wild- type EBC-2/R cells), clinically relevant concentrations of gefitinib (1 microM) induced prominent premature senescence instead of apoptosis in these cells. This induction of senescence was preceded by immediate increase of p16INK4A, p21WAF1/Cip1 and p27Kip1 levels and subsequent G1 cell cycle arrest. These phenomena were not observed in gefitinib-resistant (RERF-LC-MS) cells. Additionally, ex vivo exposure to gefitinib induced senescence in short-term cultured tumor cells that were obtained from malignant pleural effusion of a patient with NSCLC, whose tumor was later revealed to be clinically sensitive to gefitinib. Our results indicate that senescence might be a major anti-tumor mechanism of gefitinib in these NSCLC cells regardless of the EGFR gene mutation status.

Triple Combination Chemotherapy with Cisplatin, Docetaxel, and Irinotecan for Advanced Non-small Cell Lung Cancer: A Phase I/II Trial

BACKGROUND

To determine the recommended dose and evaluate the response rate and toxicity of triplet chemotherapy using cisplatin, docetaxel, and irinotecan for non-small cell lung cancer (NSCLC) patients with stage IIIB or IV.

METHODS

A total of 65 patients (33 men and 32 women) with advanced NSCLC, a good performance status, and 65 years of age or younger were included in these phase I/II studies. The median age was 52 years. Most patients had performance status 1 (49/65) and stage IV disease (49/65). Adenocarcinoma was the most common tumor histology (55 patients). Cisplatin and docetaxel were given on day 1 and irinotecan on day 2; the cycles were repeated every 3 weeks.

RESULTS

In the phase I study, the maximum tolerated doses of combination cisplatin/docetaxel/irinotecan were, respectively, 80/60/60 (mg/m) and the recommended doses for the phase II study were determined to be 60/60/60 (mg/m), respectively. The dose-limiting toxicities were neutropenia, neutropenic fever, and diarrhea. In the phase II study, 157 cycles of chemotherapy were delivered to 49 patients (median three cycles per patient). The objective response rate was 57.1% (95% confidence interval: 43.1%-71.1%). The median survival time and the actual 2-, 3- and estimated 5-year survival rates were 17 months, 33%, 25%, and 18%, respectively. Grade 3/4 toxicities consisted of neutropenia (92%), neutropenic fever (45%), nausea/vomiting (27%), diarrhea (35%), and hepatic toxicity (2%); there were no cases of treatment-related death.

CONCLUSION

This triplet chemotherapy has shown a promising activity against advanced NSCLC according to admission-based treatment with adequate supportive care. The principal toxicity was neutropenic fever, but supportive care should be explored to reduce this incidence.

Recent improvement in lung cancer screening: a comparison of the results carried out in two different time periods

To evaluate recent improvements in lung cancer screening, we compared the results of recently conducted lung cancer screening with those of a previous screening. This study compared the survival of lung cancer patients detected by lung cancer screening conducted between 1976 and 1984 (early period) with that conducted between 1989 and 1997 (late period). Two hundred seventy-six patients with lung cancer were detected in the early period and 541 patients with lung cancer were detected in the late period. The median survival time (late : 49.8 vs. early : 27.8 months) and the 5-year survival rate (late : 47.8 vs. early : 34.8%) of the patients with lung cancer detected in the late period were significantly better than those in the early period (p = 0.0054). Among patients undergoing resection, the proportion of pathological stage I patients in the late period was significantly higher than that in the early period (late : 60.8 vs. early : 54.9%, p = 0.005). Multivariate analysis showed that the screening time period was a significant prognostic factor (hazard ratio = 0.685, 95% confidence interval : 0.563-0.832, p = 0.0002). These results were consistent with the findings of case-control studies of lung cancer screening programs in the late period recently conducted in Japan, which also showed a greater efficacy for screening than for previous case-control studies in the early period.

A phase I and pharmacological study of amrubicin and topotecan in patients of small-cell lung cancer with relapsed or extensive-disease small-cell lung cancer

Cisplatin-based chemotherapy is considered to be a standard treatment in patients with relapsed or extensive-disease (ED) small-cell lung cancer (SCLC), the survival benefit remains modest. Relapsed or ED-SCLC patients were enrolled. Topotecan and amrubicin were administered on Days 1-5 and on Days 3-5, respectively. Nine patients received a total of 24 cycles. Since all three patients experienced dose-limiting toxicity (grade 4 neutropenia lasting for more than 4 days, grade 3 febrile neutropenia, and grade 4 thrombocytopenia) at the third dose level (topotecan: 0.75 mg/m2, amrubicin 40 mg/m2), the maximum tolerated dose was determined to be this dose level. Objective response was observed in six patients (67%). The maximum concentration (Cmax) and area under the plasma concentration-time curve (AUC) of amrubicin increased in a dose-dependent manner. Amrubicin did not influence the pharmacokinetics of topotecan. The Cmax and AUC of amrubicin were correlated with the duration of grade 4 neutropenia. The mean Cmax of topotecan on day 2 in responders (22.9+/-3.6) was significantly higher than that in non-responders (10.9+/-0.4). This phase I study showed the safety and activity of two-drug combination of amrubicin and topotecan in patients with relapsed or ED-SCLC.

Role of early serial change in serum carcinoembryonic antigen levels as a predictive marker for gefitinib sensitivity in Japanese patients with non-small cell lung cancer

17029

Background: The aim was to evaluate the utility of an early change in CEA levels for predicting subsequent gefitinib sensitivity in NSCLC patients. Methods: CEA level was measured before and after the beginning of gefitinib treatment (day1) in 110 (91%) of consecutive 121 patients. Daily decline rate of CEA was simply defined for each patient as follows: (M0−Mx)/Dx/M0*100(%), with the baseline level (M0), the level on days × (Mx), and days from day 1 to day X (Dx). Results: Patient characteristics were as follows; median age: 62, M/F: 61/39%, Ad/others: 84/16% and smoker: 66%. Objective response rate and disease control rate were 28.2% and 74.5%, respectively. Median baseline CEA level was 12.6 ng/mL. Daily decline rate of CEA level from day 1 to the date on which confirmation of objective response was performed significantly differed among the response categories; median decreases in percentages were 0.86, 0.06, and −1.52%/day in CR/PR, SD, and PD patients, respectively (p < 0.0001). This association was more evident in the 70 patients with abnormal baseline CEA level (≥5.0 ng/mL). A cutoff level of −0.58% decrease per day most accurately reflected tumor shrinkage in the 70 patients, with sensitivity, specificity, and positive and negative predictive values for disease control (CR/PR/SD) of 89.1, 73.3, 92.5 and 64.7%, respectively. Among 49 (41%) patients reassessed CEA levels within the first 2 weeks since day 1, 41 could continue the treatment without any disease progression during this period. The daily decline rate in this early phase tended to differ between the responses (median; 1.57 and −0.50% in CR/PR/SD and PD, respectively; p = 0.0975), and less exactly reflected disease control with sensitivity, specificity, and positive and negative predictive values of 82.1, 40.0, 88.5, and 28.6%, respectively when a cutoff of −0.58% was applied. Conclusion: Degree of change in CEA level from the start of gefitinib treatment to confirmation of objective response significantly correlated with tumor shrinkage. As a predictor for obtaining disease control, monitoring early change in CEA level might be useful due to high sensitivity and positive predictive value, in spite of low specificity for detection of PD patients.

No significant financial relationships to disclose.

Never-smoking history predicts long-term survival in patients with non-small cell lung cancer with postoperative recurrence

20047

Background: Factors affecting long-term survival after postoperative recurrence in non-small cell lung cancer (NSCLC) patients have not been fully understood. Furthermore, molecular features of them also have remained undetermined. The aim of this study was to identify these possible factors and to investigate their association with epidermal growth factor receptor (EGFR) mutation. Methods: Fifty-eight patients with postoperative recurrent NSCLC treated at Okayama University Hospital between January 1999 and December 2003 were retrospectively analyzed. We defined those surviving for 2 years or longer after postoperative recurrence as long-term survivors. Tumor samples for EGFR mutation analysis were available in 32 (55%) patients and were examined in exons 18 to 21 of EGFR using direct sequence method. Results: Demographics of 58 patients were as follows: median age 65 years (range, 33–85 years), male/female, 69%/31%; adenocarcinoma/others, 69%/31%; ever/never-smokers, 66%/34% and local/local and distant/distant recurrence; 29%/10%/61%. Median survival time and 1-year survival rate for 58 patients were 22.7 months and 79%, respectively, with a minimum follow-up time of 2 years. Half of 28 long-term survivors did not have any smoking history, whereas only 6 never-smokers were included in the remaining 30 patients who died within 2 years, indicating that never-smoking history is significantly associated with long-term survival (p=0.016). In multivariate analysis, never-smoking history was a significant predictive factor for long-term survival (Odds ratio 4.90, 95% confidence interval: 1.26–19.00, p=0.022). Among 32 patients analyzed for EGFR mutation, patients harboring EGFR mutation in ever-smokers and in never-smokers were 10% and 82%, respectively. Seven (47%) of 15 long-term survivors analyzed had EGFR mutation; however, only 4 (24%) of 17 patients who died within 2 years did (p = 0.169). Conclusions: Our data suggest that never-smoking history might have a favorable effect on long-term survival in postoperative recurrent NSCLC patients, and long-term survivors tend to have EGFR mutation.

No significant financial relationships to disclose.

Clinical factors affecting the late resistance to gefitinib in patients with non-small cell lung cancer (NSCLC)

7191

Background: The mechanism of late resistance of NSCLC to gefitinib is unclear. In this study, we assessed clinical factors affecting the late resistance in patients with NSCLC. Methods: Between 2000 and 2004, 197 consecutive patients with NSCLC underwent treatment with gefitinib in our institutions. Of those, 56 patients who had received a prior chemotherapy and continued treatment with gefitinib during at least 6 months were included in this study. The characteristics of these patients were as follows: median age, 62.5 years (range, 28 to 77 years); male/female, 22/34 patients; PS 0/1/2/3/4, 15/31/8/0/2 patients; and adeno/nonadenocarcinoma, 52/4 patients. Thirty-two patients never smoked and 24 were former or current smokers. Nineteen patients underwent surgical resection of NSCLC. Numbers of chemotherapy regimens were one in 31 patients, two in 18, three in 6, four in 1, respectively. Results: Of 56 patients, three achieved a CR and 39 attained a PR, with an overall response rate of 75% (95% CI, 69.2 to 80.8%). The remaining 14 patients had a long SD. At a median follow-up time of 21.6 months (range, 7.7 to 59.7 months), median time to progression was 19.5 months, with progression-free survival rates of 68.5% at 1-year, 33.6% at 2-year, and 21.2% at 3-year, respectively. In a univariate analysis regarding progression-free survival, presences of metastasis to brain (p = 0.008), bone (p = 0.025), liver (p = 0.046), and adrenal (p = 0.008), decreased levels of hemoglobin (p = 0.021) and albumin (p = 0.017), and use of multiple chemotherapy regimens prior to treatment with gefitinib (p = 0.026) were significant factors. In a multivariate analysis using Cox proportional hazard model, presence of brain metastasis was a significant factor clinically affecting the late resistance to gefitinib (hazard ratio, 2.14; 95% CI, 1.10 to 4.17, p = 0.025). In addition, decreased hemoglobin level (p = 0.074) and prior multiple chemotherapy regimens (p = 0.069) were tended to be significant. Conclusions: In patients undergoing treatment with gefitinib, presence of brain metastasis was an important factor indicative of the emergence of late resistance in this study. It is needed to confirm this finding in a large cohort of patients with NSCLC.

No significant financial relationships to disclose.

Choroidopathy with serous retinal detachment in a patient with polymyositis

PURPOSE

The authors report a unique case of multifocal choroidopathy in association with polymyositis.

METHODS

The clinical presentation, laser treatment, and subsequent change in ocular findings are described.

RESULTS

A 65-year-old Japanese man with polymyositis experienced mid acute vision impairment in both eyes during systemic corticosteroid treatment for interstitial pneumonia. Fundus examination revealed a gray-white subretinal exudate with serous retinal detachment. Angiographic examination disclosed partial dilatation of the choroidal vein at the posterior pole and dye leakage points in the retinal pigment epithelium. The patient's left eye developed bullous retinal detachment and multi focal choroidal nodules at the posterior pole during the period of tapering of oral corticosteroid administration. Retinal burns were applied to the dye leakage points in the right eye using an argon laser. Vision in the right eye showed rapid recovery due to regression of the serous retinal detachment. However, in the left eye without retinal burns visual acuity decreased to light perception only even after regression of the bullous retinal detachment and choroidopathy.

CONCLUSIONS

In serous retinal detachment with choroidopathy associated with polymyositis, laser photocoagulation at leakage points may be useful for rapid restoration of vision and for the prevention of permanent severe vision loss.

Clustered incidence of acute promyelocytic leukemia during gefitinib treatment for non-small-cell lung cancer: experience at a single institution

Although gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has been shown a significant activity for recurrent non-small-cell lung cancer (NSCLC), its long-term adverse effect with its continuous usage has hitherto not been clearly elucidated. Subjects were 108 consecutive NSCLC cases who were treated with gefitinib between November 2001 and December 2004 at our single institution. A crude incidence rate ratio was calculated by ratio of crude incidence rate in our subject to population-based incident rate of all leukemia (ICD: C91-95) in the same region. The 95% confidence intervals (CIs) were calculated based upon a Poisson distribution. Three cases of acute promyelocytic leukemia (APL) occurred during gefitinib treatment, and these patients' past treatment histories are presented herein. No other malignancy was identified. All of the cases were diagnosed at the stage of mild-to-moderate cytopenia, especially thrombocytopenia, without disseminated intravascular coagulation. All presented a normal karyotype with positive PML-RARalpha in RT-PCR, indicating submicroscopic translocation. They responded well to APL treatments, including all-trans-retinoic acid. The crude incident rate ratio was 639.9 (95% confidence interval: 131.6-1,878.9, P < 0.0001) when the APL incidence in this cohort was compared to all leukemia cases in the general population in the same district in Japan. Thus we had three cases of secondary APL patients within the gefitinib-treated NSCLC cohort. Although we cannot exclude an effect of past exposure of other cytotoxic agents and radiotherapy as a cause of APL, APL inducibility of gefitinib should be clarified in the further study.

The combination effect of amrubicin with cisplatin or irinotecan for small-cell lung cancer cells

The single agent of amrubicin is active in untreated small-cell lung cancer (SCLC). Cytotoxicity of amrubicinol, the active form of amrubicin, was evaluated in a parent SCLC cell line (SBC-3); an active metabolite of irinotecan, 7-ethyl-10-hydroxy-camptothecin (SN-38)-resistant subline (SBC-3/SN-38); and cisplatin-resistant subline (SBC-3/CDDP) using AlamarBlue assay. Interaction of the combined drugs was evaluated by median-effect plot analysis, and the fraction of apoptotic cells was determined using flow cytometry. SBC-3/SN-38 was 34-fold more resistant to SN-38 and SBC-3/CDDP was 7.2-fold more resistant to cisplatin than parental SBC-3. However, these resistant sublines retained sensitivity to amrubicinol (1.8- and 1.7-fold, respectively). Simultaneous exposure of SBC-3/SN-38 cells to amrubicinol and cisplatin showed a synergistic effect. Simultaneous exposure of SBC-3/CDDP cells to amrubicinol and SN-38 displayed synergistic or additive effects. The two-drug combination produced an increase of apoptotic cells compared to each single agent alone in both resistant cells. These findings suggest that amrubicin alone and in combination with cisplatin or irinotecan is effective against SCLC refractory to irinotecan and/or cisplatin.