When accurate prediction models yield harmful self-fulfilling prophecies

Prediction models are popular in medical research and practice. Many expect that by predicting patient-specific outcomes, these models have the potential to inform treatment decisions, and they are frequently lauded as instruments for personalized, data-driven healthcare. We show, however, that using prediction models for decision-making can lead to harm, even when the predictions exhibit good discrimination after deployment. These models are harmful self-fulfilling prophecies: their deployment harms a group of patients, but the worse outcome of these patients does not diminish the discrimination of the model. Our main result is a formal characterization of a set of such prediction models. Next, we show that models that are well calibrated before and after deployment are useless for decision-making, as they make no change in the data distribution. These results call for a reconsideration of standard practices for validation and deployment of prediction models that are used in medical decisions.

Small-Cell Lung Cancer: Is Liquid Biopsy a New Tool Able to Predict the Efficacy of Immunotherapy?

Small-cell lung cancer (SCLC) cases represent approximately 15% of all lung cancer cases, remaining a recalcitrant malignancy with poor survival and few treatment options. In the last few years, the addition of immunotherapy to chemotherapy improved clinical outcomes compared to chemotherapy alone, resulting in the current standard of care for SCLC. However, the advantage of immunotherapy only applies to a few SCLC patients, and predictive biomarkers selection are lacking for SCLC. In particular, due to some features of SCLC, such as high heterogeneity, elevated cell plasticity, and low-quality tissue samples, SCLC biopsies cannot be used as biomarkers. Therefore, the characterization of the tumor and, subsequently, the selection of an appropriate therapeutic combination may benefit greatly from liquid biopsy. Soluble factors, circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and extracellular vesicles (EVs) are now useful tools in the characterization of SCLC. This review summarizes the most recent data on biomarkers detectable with liquid biopsy, emphasizing their role in supporting tumor detection and their potential role in SCLC treatment choice.

Prognostic significance of distant metastasis-free interval in patients with relapsed melanoma treated with BRAF with or without MEK inhibitors

This retrospective cohort study assessed the prognostic significance of distant metastasis-free interval (DMFI) in patients with relapsed BRAF-mutant melanoma treated with BRAF with or without MEK inhibitors (BRAFi ± MEKi). Patients with a DMFI of up to 24 months were compared with those with DMFI of more than 24 months, with regard to their postrelapse progression-free survival (PR-PFS) and overall survival (PR-OS). In total, 109 patients were included in the study. Median DMFI was 25.3 (range: 3.4-188.2) months. Median PR-PFS in patients with DMFI of more than 24 months was 7.9 months [95% confidence interval (CI): 6.2-9.7] compared with 5.4 (95% CI: 4.2-6.7) months of those with shorter DMFI (P = 0.016). Median PR-OS was 15.6 months (95% CI: 13.6-17.6) in patients with DMFI of more than 24 months and 12.0 months (95% CI: 9.0-15.0) with DMFI of up to 24 months (P = 0.289). Multivariate Cox regression analysis showed that DMFI was independently and strongly associated with improved PR-PFS (adjusted hazard ratio = 3.21, 95% CI: 1.78-5.77, ≤ 24 vs. > 24 months) and longer PR-OS (adjusted hazard ratio: 2.09, 95% CI: 1.15-3.80, ≤ 24 vs. > 24 months). The present cohort study is one of the first to confirm the association of DMFI of more than 24 months with an indolent disease course, as shown by longer PR-PFS and PR-OS, in patients with relapsed stage IV melanoma treated by BRAF inhibitor/MEK inhibitor.

Calycosin Enhances Some Chemotherapeutic Drugs Inhibition of Akt Signaling Pathway in Gastric Cells

Although diagnosis and treatment of gastric cancer have improved, the prognosis of patients remains poor. The majority of patients should be treated with chemotherapy or other follow-up treatment. However, the drug resistance of chemotherapy and heterogeneity of tumor itself lead to differences of sensitivity of chemotherapy drugs for different patients. Therefore, it is mandatory to develop better methods of treatment for treatment of gastric cancer. Calycosin has been used in several types of cancer cells. Cisplatin, 5-fluorouracil (5-FU), and adriamycin (ADM) are most widely used drugs for chemotherapy, and they improve the overall survival of cancer patients. To study whether and how calycosin enhances their inhibition of gastric cancer cells, we detected the signaling pathway in which calycosin and cisplatin, 5-FU, and ADM play role in human gastric cells lines. We found that calycosin can enhance the suppression of cisplatin to gastric cell line by inhibiting the phosphorylation of protein kinase B (Akt). So, when cisplatin/5-FU/ADM is combined with calycosin, it can achieve better therapeutic effect in lower concentration.

HMGB1 Enhances Drug Resistance and Promotes In Vivo Tumor Growth of Lung Cancer Cells

Drug resistance is an obstacle in the chemotherapeutic treatment of lung cancers. In the present study, the effects of high-mobility group box 1 (HMGB1) protein in chemotherapeutic resistance and the relationships between HMGB1 and chemotherapy drug-induced cell apoptosis or necrosis were clarified. We used cisplatin-sensitive A549 cells and cisplatin-resistant A549/DDP cells as cell models with IC50 of 11.58 and 46.95 μM, respectively. A549/DDP had higher level of HMGB1 compared with A549 cells. Interestingly, with the increasing concentration of DDP, HMGB1 was gradually located into cytoplasm in cisplatin-sensitive A549 cells. Moreover, interference with endogenous HMGB1 sensitized the effects of chemotherapeutic drugs, including 5-Fu, DDP, and OXA. Furthermore, results from an in vivo tumorigenesis experiment demonstrated that serum concentration of HMGB1 was much lower in the group inoculated with HMGB1 shRNA-transfected A549 cells than in the N.C. shRNA-transfected A549 inoculated group, as well as the tumor volume, suggesting that serum HMGB1 contributed to tumor growth in a mouse model. In conclusion, higher levels of HMGB1 probably contributed to chemotherapy drug resistance, and higher serum concentration of HMGB1 promoted in vivo tumor growth. The study would provide new clues to overcome drug resistance in chemotherapy of human lung cancers.

Autophagy inhibition upregulates CD4+ tumor infiltrating lymphocyte expression via miR-155 regulation and TRAIL activation

Chemoresistance is a major challenge in lung cancer treatment. Recent findings have revealed that autophagic mechanism contributes significantly to immunosuppressive related chemoresistance. For that reason, targeting autophagy-related immunosuppression is an important approach to reverse tumor drug resistance. In this study, we report for the first time that autophagy inhibition triggers upregulation of CD4⁺, Foxp3⁺ tumor infiltrating lymphocytes in late metastatic lung cancer tissues. Furthermore, autophagy blockage induces chemosensitization to carboplatin, immune activation and cell cycle arrest. This induction correlated with reduction in expression of drug resistance genes MDR1, MRP1, ABCG2 and ABCC2 along with decreased expression of PD-L1 which is associated with severe dysfunction of tumor specific CD8⁺ T cells. Furthermore, experiments revealed that co-treatment of carboplatin and autophagy inhibitor chloroquine increased lung tissue infiltration by CD4⁺, FoxP3⁺ lymphocytes and antigen-specific immune activation. Subsequent ex vivo experiments showed the activation of carboplatin related TRAIL-dependent apoptosis through caspase 8 and a synergistic role of miR-155 in lung tissue infiltration by CD4⁺, and FoxP3⁺ lymphocytes. Overall, our results indicate that autophagy blockage increases lung cancer chemosensitivity to carboplatin, but also reveal that miR-155 functions as a novel immune system activator by promoting TILs infiltration. These results indicate that targeting of autophagy can prevent cancer related immunosuppression and elucidate immune cell infiltration in tumor microenvironment thus representing a potential therapeutic strategy to inhibit lung cancer progression and metastasis.

SCLC-State of the Art and What Does the Future Have in Store?

Worldwide, the total number of diagnosed lung cancer cases amounts to 1.8 million every year. Small-cell lung cancer (SCLC) accounts for about 15% to 17% of all diagnosed lung cancers. Despite all progress made in the field of non-small-cell lung cancer, the prognosis and therapeutic options in SCLC are still limited. The resistance of SCLC to conventional therapy as well as its high recurrence rate can be attributed to the heterogeneous genetic structure of SCLC; however, a targeted therapy approach to SCLC may build on this very heterogeneous genetic structure. SCLC is by now a well-characterized cancer with various genetic alterations; for example, mutations in tumor suppressor genes TP53 and RB1, alterations in chromosome 3p, JAK2, FGFR1, and MYC genes were discovered. Based on these findings, various treatment options (eg, aurora kinase inhibitors, PARP inhibition, immune checkpoint inhibition and vaccine therapy) are currently evaluated with the goal of determining their clinical effectiveness. In this article, we review the existing knowledge of SCLC genetics and the current treatment standards and highlight new approaches of immunotherapy and other targeted therapies, which may yield new treatment options and improve the outcome of patients with SCLC.

14-3-3σ attenuates RhoGDI2-induced cisplatin resistance through activation of Erk and p38 in gastric cancer cells

Rho GDP dissociation inhibitor 2 (RhoGDI2) promotes tumor growth and malignant progression and enhances chemoresistance of gastric cancer. Recently, we noted an inverse correlation between RhoGDI2 and 14-3-3σ expression, which suggests that 14-3-3σ is a target of gastric cancer metastasis and the chemoresistance-promoting effect of RhoGDI2. Herein, we evaluated whether 14-3-3σ is regulated by RhoGDI2 and is functionally important for the RhoGDI2-induced cisplatin resistance of gastric cancer cells. We used highly metastatic and cisplatin-resistant RhoGDI2-overexpressing SNU-484 cells and observed decreased 14-3-3σ mRNA and protein expression. Depletion of 14-3-3σ in SNU-484 control cells enhanced cisplatin resistance, whereas restoration of 14-3-3σ in RhoGDI2-overexpressing SNU-484 cells impaired cisplatin resistance in vitro and in vivo. We also found that the phosphorylation levels of Erk and p38 kinases significantly decreased in RhoGDI2-overexpressing SNU-484 cells and recovered after 14-3-3σ expression, and that decreased activities of these kinases were critical for RhoGDI2-induced cisplatin resistance. In conclusion, 14-3-3σ is a RhoGDI2-regulated gene that appears to be important for suppressing the chemoresistance of gastric cancer cells.

EGFR activating mutations and their association with response to platinum-doublet chemotherapy in Brazilian non-small cell lung cancer patients

The aim of the study was to analyze the frequency of epidermal growth factor receptor (EGFR) mutations in Brazilian non-small cell lung cancer patients and to correlate these mutations with response to benefit of platinum-based chemotherapy in non-small cell lung cancer (NSCLC). Our cohort consisted of prospective patients with NSCLCs who received chemotherapy (platinum derivates plus paclitaxel) at the [UNICAMP], Brazil. EGFR exons 18-21 were analyzed in tumor-derived DNA. Fifty patients were included in the study (25 with adenocarcinoma). EGFR mutations were identified in 6/50 (12 %) NSCLCs and in 6/25 (24 %) adenocarcinomas; representing the frequency of EGFR mutations in a mostly self-reported White (82.0 %) southeastern Brazilian population of NSCLCs. Patients with NSCLCs harboring EGFR exon 19 deletions or the exon 21 L858R mutation were found to have a higher chance of response to platinum-paclitaxel (OR 9.67 [95 % CI 1.03-90.41], p = 0.047). We report the frequency of EGFR activating mutations in a typical southeastern Brazilian population with NSCLC, which are similar to that of other countries with Western European ethnicity. EGFR mutations seem to be predictive of a response to platinum-paclitaxel, and additional studies are needed to confirm or refute this relationship.

Cisplatin for small cell lung cancer: Associated publications in Science Citation Index Expanded

This study was conducted to explore a bibliometric approach to quantitatively assess current research trends in cisplatin-containing chemotherapy for small cell lung cancer (SCLC), using related literature in the Science Citation Index Expanded database from 1992 to 2011. Articles were analyzed by the scientific output and research performances of countries and institutions. The distribution of key words in the article title and author-selected keywords were used to evaluate research trends. It was observed that the number of articles devoted to cisplatin-containing chemotherapy for SCLC did not increase with time. The USA and Japan were the top two countries with the highest number of articles devoted to cisplatin-containing chemotherapy for SCLC. In both countries, the number of articles did not increase with time, and a decreasing trend was identified in the USA over the last 10 years. This study demonstrates trends in cisplatin-containing chemotherapy for SCLC. The clinical application of novel drugs is required for successful SCLC treatment.

Thymoquinone as an anticancer agent: evidence from inhibition of cancer cells viability and invasion in vitro and tumor growth in vivo

Phytochemical compounds are emerging as a new generation of anticancer agents with limited toxicity in cancer patients. The purpose of this study was to investigate the potential impact of thymoquinone (TQ), the major constituent of black seed, on survival, invasion of cancer cells in vitro, and tumor growth in vivo. Exposure of cells derived from lung (LNM35), liver (HepG2), colon (HT29), melanoma (MDA-MB-435), and breast (MDA-MB-231 and MCF-7) tumors to increasing TQ concentrations resulted in a significant inhibition of viability through the inhibition of Akt phosphorylation leading to DNA damage and activation of the mitochondrial-signaling proapoptotic pathway. We provide evidence that TQ at non-toxic concentrations inhibited the invasive potential of LNM35, MDA-MB-231, and MDA-MB231-1833 cancer cells. Moreover, we demonstrate that TQ synergizes with DNA-damaging agent cisplatin to inhibit cellular viability. The anticancer activity of thymoquinone was also investigated in athymic mice inoculated with the LNM35 lung cells. Administration of TQ (10 mg/kg/i.p.) for 18 days inhibited the LNM35 tumor growth by 39% (P < 0.05). Tumor growth inhibition was associated with significant increase in the activated caspase-3. The in silico target identification suggests several potential targets of TQ mainly HDAC2 proteins and the 15-hydroxyprostaglandin dehydrogenase. In this context, we demonstrated that TQ treatment resulted in a significant inhibition of HDAC2 proteins. In view of the available experimental findings, we contend that thymoquinone and/or its analogues may have clinical potential as an anticancer agent alone or in combination with chemotherapeutic drugs such as cisplatin.

Specific organ metastases and survival in small cell lung cancer

The aim of our retrospective study was to evaluate the clinicopathological features associated with distant metastasis from small cell lung cancer (SCLC). We reviewed patients diagnosed with SCLC metastasis at the time of presentation between 1999 and 2010. Among the consecutive 251 SCLC patients diagnosed, 152 (60.6%) patients had distant metastasis, of which 20.3, 18.3, 15.5, 10.0 and 6.0% of patients had liver, bone, brain, lung and adrenal gland metastasis, respectively. In a multivariate analysis using Cox's proportional hazards model, we identified that liver, bone and brain metastasis as well as the presence of pleural and/or pericardial fluids were unfavorable prognostic factors. However, lung, adrenal gland and extrathoracic lymph node metastasis were not statistically significant prognostic factors. With regard to the treatment of SCLC patients, particularly those with liver, bone and brain metastasis or pleural and/or pericardial fluids, we should take the metastasizing organs into consideration.

Higher expression of Caveolin-1 inhibits human small cell lung cancer (SCLC) apoptosis in vitro

Small cell lung cancer (SCLC) is the most aggressive type of lung cancer, and its treatment is closely associated with apoptosis. Caveolin-1 plays an important role in the development of a variety of human cancers. This study sought to investigate the influence of Caveolin-1 on the apoptosis of SCLC in vitro. We demonstrate that higher expression of Caveolin-1 leads to inhibition of cisplatin and Ultraviolet Radiation (UVR)-induced apoptosis in SCLC cells; and also could decrease caspase-3 activity and increase the stability of Bcl-2 at the protein level. Our findings illuminate a potential molecular mechanism regarding CAV-1's role as anti-apoptosis protein.

Proteomics-based strategy to delineate the molecular mechanisms of RhoGDI2-induced metastasis and drug resistance in gastric cancer

Rho GDP dissociation inhibitor 2 (RhoGDI2) was initially identified as a regulator of the Rho family of GTPases. Our recent works suggest that RhoGDI2 promotes tumor growth and malignant progression, as well as enhances chemoresistance in gastric cancer. Here, we delineate the mechanism by which RhoGDI2 promotes gastric cancer cell invasion and chemoresistance using two-dimensional gel electrophoresis (2-DE) on proteins derived from a RhoGDI2-overexpressing SNU-484 human gastric cancer cell line and control cells. Differentially expressed proteins were identified using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF-MS). In total, 47 differential protein spots were identified; 33 were upregulated, and 14 were downregulated by RhoGDI2 overexpression. Upregulation of SAE1, Cathepsin D, Cofilin1, CIAPIN1, and PAK2 proteins was validated by Western blot analysis. Loss-of-function analysis using small interference RNA (siRNA) directed against candidate genes reveals the need for CIAPIN1 and PAK2 in RhoGDI2-induced cancer cell invasion and Cathepsin D and PAK2 in RhoGDI2-mediated chemoresistance in gastric cancer cells. These data extend our understanding of the genes that act downstream of RhoGDI2 during the progression of gastric cancer and the acquisition of chemoresistance.

Small cell lung cancer in a 14-year-old girl

Pediatric lung cancer is uncommon, and small cell lung cancer (SCLC) is exceptionally rare. A 14-year-old previously healthy girl was diagnosed with limited-stage SCLC, which was considered inoperable. She responded well to chemotherapy with carboplatin and etoposide, and surgical resection was performed after 2 cycles. High-dose thoracic radiotherapy in combination with etoposide and carboplatin was given as postoperative treatment. The patient died of relapsing disease 21 months after initial diagnosis. Only 1 single case report on SCLC has been published earlier. Additional reports on pediatric SCLC are needed to evaluate appropriate treatment.

PLCγ is required for RhoGDI2-mediated cisplatin resistance in gastric cancer

Rho GDP dissociation inhibitor 2 (RhoGDI2) is a regulator of the Rho family GTPases. Recent work from our laboratory suggests that RhoGDI2 expression potentially enhances resistance to cisplatin as well as promotes tumor growth and malignant progression in gastric cancer. In this study, we demonstrate that phospholipase C-gamma (PLCγ) is required for RhoGDI2-mediated cisplatin resistance and cancer cell invasion in gastric cancer. The levels of phosphorylated PLCγ are markedly enhanced in RhoGDI2-overexpressing SNU-484 cells and, by contrast, repressed in RhoGDI2-depleted MKN-28 cells. Depletion of PLCγ expression or inhibition of its activity not only significantly increases cisplatin-induced apoptosis but also suppresses the invasive ability of RhoGDI2-overexpressing SNU-484 cells. Taken together, our results suggest that PLCγ plays a key role in RhoGDI2-mediated cisplatin resistance and cell invasion in gastric cancer cells.

RhoGDI2 confers gastric cancer cells resistance against cisplatin-induced apoptosis by upregulation of Bcl-2 expression

Rho GDP dissociation inhibitor (RhoGDI)2 has been identified as a regulator of Rho family GTPase. Recently, we suggested that RhoGDI2 could promote tumor growth and malignant progression in gastric cancer. In this study, we demonstrate that RhoGDI2 contributes to another important feature of aggressive cancers, i.e., resistance to chemotherapeutic agents such as cisplatin. Forced expression of RhoGDI2 attenuated cisplatin-induced apoptosis, whereas RhoGDI2 depletion showed opposite effects in vitro. Moreover, the increased anti-apoptotic effect of RhoGDI2 on cisplatin was further validated in RhoGDI2-overexpressing SNU-484 xenograft model in nude mice. Furthermore, we identified Bcl-2 as a major determinant of RhoGDI2-mediated cisplatin resistance in gastric cancer cells. Depletion of Bcl-2 expression significantly increased cisplatin-induced apoptosis in RhoGDI2-overexpressing gastric cancer cells, whereas overexpression of Bcl-2 blocked cisplatin-induced apoptosis in RhoGDI2-depleted gastric cancer cells. Overall, these findings establish RhoGDI2 as an important therapeutic target for simultaneously enhancing chemotherapy efficacy and reducing metastasis risk in gastric cancer.

ERCC1 and Ki67 in small cell lung carcinoma and other neuroendocrine tumors of the lung: distribution and impact on survival

BACKGROUND

Excision repair cross-complementation group 1 (ERCC1) is a key component of the platinum-DNA repair mechanism. Ki67 is associated with the clinical course of several malignancies. The associations of ERCC1 and Ki67, clinical features and survival in small cell lung carcinoma (SCLC), typical carcinoid (TC), atypical carcinoid (AC), and large cell neuroendocrine carcinoma (LCNEC) were determined.

MATERIALS AND METHODS

We included a consecutive series of 186 patients with SCLC treated with platinum-based chemotherapy and surgically treated patients with TC (n = 48), AC (n = 15) and LCNEC (n = 27). ERCC1 and Ki 67 were measured by immunohistochemistry and scored using published criteria.

RESULTS

The expression of ERCC1 was different among the different tumor types (p < 0.001). For patient with limited disease as well as extensive disease SCLC, no association of ERCC1 expression with survival was observed (p = 0.59). However, only 10% of SCLC tumors expressed ERCC1. For TC and AC, ERCC1 positive patients had better survival than ERCC1 negative patients. ERCC1 had no prognostic impact for LCNEC. A difference of the percentage of Ki67 LI was observed for the different tumor types (p < 0.001). The difference between TC and AC was significant (p = 0.02), as was the difference between low grade (TC+AC) and high grade NE (LCNEC + SCLC) (p < 0.001). For all included patients, a correlation between Ki67 and ERCC1 was observed (RSquare = 0.19, p < 0.001).

CONCLUSION

ERCC1 expression in SCLC treated with platinum-based chemotherapy has no impact on survival. High expression of ERCC1 in TC might represent a clue to the failure of platinum-based therapy in these patients. ERCC1 expression has prognostic impact in lung carcinoids. Ki 67 might be considered as a supplementary test to the histopatologic classification of NE tumors.

Preclinical evidence for a beneficial impact of valproate on the response of small cell lung cancer to first-line chemotherapy

Prognosis of small cell lung carcinoma (SCLC) is particularly poor, less than 5% of patients with extensive stage being alive after two years. We hypothesized that SCLC chemotherapy could be improved by using histone deacetylase (HDAC) inhibitors based on their ability to interfere with lysine acetylation and to alter gene expression. The goal of this study was to evaluate the anticancer efficacy of a HDAC inhibitor (valproate: VPA) on SCLC cells in combination with the standard chemotherapeutic first-line regimen (cisplatin+etoposide). We show that VPA induces apoptosis of small cell lung cancer cell lines and improves efficacy of cisplatin combined with etoposide. Both mitochondrial and death receptor pathways are involved in VPA-induced apoptosis. As expected for an HDAC inhibitor, VPA hyperacetylates histone H3. The mechanism of VPA pro-apoptotic activity involves induction of p21, inhibition of Bcl-xL, cleavage of Bid and phosphorylation of Erk and H2AX. In the presence of VPA, Bax is translocated from the cytoplasm to the mitochondria and cleaved in an 18kDa isoform. Cytochrome c is released from the mitochondria into the cytosol. Transcriptomic analyses by microarray show that VPA modulates transcription of genes (Na(+)/K(+) ATPase, Bcl-xL) involved in chemoresistance to cisplatin and etoposide. Finally, the efficacy of VPA combined with cisplatin and etoposide is supported by preclinical models of SCLC cells engrafted into SCID mice. Together, these data demonstrate that VPA augments anticancer activity of cisplatin and etoposide, two components of the standard first-line chemotherapy of small cell lung cancer.

High temperature requirement A3 (HtrA3) promotes etoposide- and cisplatin-induced cytotoxicity in lung cancer cell lines

Lung cancer is the leading cause of cancer-related deaths worldwide. Here we show for the first time that HtrA3 is a mitochondrial stress-response factor that promotes cytotoxicity to etoposide and cisplatin in lung cancer cell lines. Exogenous expression of wild type HtrA3 domain variants significantly attenuated cell survival with etoposide and cisplatin treatment in lung cancer cell lines H157 and A549 compared with expression of protease inactive mutants (S305A) or vector control. Conversely, HtrA3 suppression promoted cell survival with etoposide and cisplatin treatment in lung cancer cell lines Hop62 and HCC827. Survival was attenuated by re-expression of wild type HtrA3 variants during treatment but not by protease inactive mutants or vector control. HtrA3 also co-fractionated and co-localized with mitochondrial markers with both endogenous and exogenous expression in normal lung and lung cancer cell lines but was translocated from mitochondria following etoposide treatment. Moreover, HtrA3 translocation from mitochondria correlated with an increase in cell death that was attenuated by either HtrA3 suppression or Bcl-2 overexpression. Taken together, these results suggest that HtrA3 may be a previously uncharacterized mitochondrial cell death effector whose serine protease function may be crucial to modulating etoposide- and cisplatin-induced cytotoxicity in lung cancer cell lines.

Validation of intratracheal instillation of lung tumour cells in mice using single photon emission computed tomography/computed tomography imaging

In search of better predictive animal models for evaluating treatment response in lung cancer, orthotopic lung tumour models are a great step forward over traditional subcutaneous models. Crucial in the development of such orthotopic models is a reliable and reproducible instillation method. Because cells are instilled inside the thorax, the accuracy of the instillation and visualization of tumour growth demands the use of non-invasive imaging methods. We used a minimally invasive intratracheal intubation method to instill bioluminescent lung tumour cells in the lung parenchyma. Adaptation of the cell containing medium provides the possibility of tracing the exact location of the injection by means of single photon emission computed tomography/computed tomography (CT) imaging. The transplantation medium was also optimized to prevent migration of the injected substance. This results in the outgrowth of single and well-defined lung tumours at the instillation site. Finally, tumour growth was validated and longitudinally monitored with a combination of CT and bioluminescence imaging. The reported transplantation procedure enables the assessment of injection accuracy and provides a good approach for the generation of orthotopic lung tumour models for future response imaging studies.

New advances in the second-line treatment of small cell lung cancer

Lung cancer is the leading cause of cancer-related death in the U.K., with small cell histology accounting for 15%-20% of cases. Small cell lung cancer (SCLC) is initially a chemosensitive disease, but relapse is common, and in this group of patients it remains a rapidly lethal disease with a particularly poor prognosis. The choice of second-line chemotherapy for patients with relapsed SCLC has been an area of difficulty for oncologists, and until recently there was no randomized evidence for its use over best supportive care (BSC). Topotecan is currently the only drug licensed in Europe and the U.S. for this indication, having been shown in a phase III trial to lead to longer overall survival and better quality of life than with BSC. In this article, we review the current evidence for the use of second-line cytotoxic therapy and also the emerging role of novel agents and targeted therapies in this setting. In particular, we explore the role of the Bcl-2 protein family, which are key regulators of mitochondrial apoptosis and are implicated in resistance to anticancer therapies. SCLC overexpresses antiapoptotic members of the Bcl-2 family in approximately 80% of cases. Several Bcl-2 inhibitors, including obatoclax, are currently entering clinical trials in SCLC and are an exciting area of drug development in the relapsed setting.

Generating inhibitors of P-glycoprotein: where to, now?

The prominent role for the drug efflux pump ABCB1 (P-glycoprotein) in mediating resistance to chemotherapy was first suggested in 1976 and sparked an incredible drive to restore the efficacy of anticancer drugs. Achieving this goal seemed inevitable in 1982 when a series of calcium channel blockers were demonstrated to restore the efficacy of chemotherapy agents. A large number of other compounds have since been demonstrated to restore chemotherapeutic sensitivity in cancer cells or tissues. Where do we stand almost three decades since the first reports of ABCB1 inhibition? Unfortunately, in the aftermath of extensive fundamental and clinical research efforts the situation remains gloomy. Only a small handful of compounds have reached late stage clinical trials and none are in routine clinical usage to circumvent chemoresistance. Why has the translation process been so ineffective? One factor is the multifactorial nature of drug resistance inherent to cancer tissues; ABCB1 is not the sole factor. However, expression of ABCB1 remains a significant negative prognostic indicator and is closely associated with poor response to chemotherapy in many cancer types. The main difficulties with restoration of sensitivity to chemotherapy reside with poor properties of the ABCB1 inhibitors: (1) low selectivity to ABCB1, (2) poor potency to inhibit ABCB1, (3) inherent toxicity and/or (4) adverse pharmacokinetic interactions with anticancer drugs. Despite these difficulties, there is a clear requirement for effective inhibitors and to date the strategies for generating such compounds have involved serendipity or simple chemical syntheses. This chapter outlines more sophisticated approaches making use of bioinformatics, combinatorial chemistry and structure informed drug design. Generating a new arsenal of potent and selective ABCB1 inhibitors offers the promise of restoring the efficacy of a key weapon in cancer treatment--chemotherapy.

A phase II study of carboplatin, etoposide, and exisulind in patients with extensive small cell lung cancer: CALGB 30104

PURPOSE

To assess the efficacy and toxicity of carboplatin, etoposide, and exisulind as initial therapy for extensive stage small cell lung cancer.

PATIENTS AND METHODS

The Cancer and Leukemia Group B conducted a phase II study of carboplatin (area under the curve 6) day 1 and etoposide 80 mg/m(2) days 1-3 administered intravenously every 21 days with exisulind 250 mg orally twice daily in 44 evaluable patients with previously untreated extensive stage small cell lung cancer. The hypothesis was the addition of a novel cytostatic agent to standard therapy may increase survival time. The primary end point of the study was to evaluate overall survival. The secondary end points were to characterize response rates and toxicity.

RESULTS

The majority of the patients were male (64%), Caucasian (95%), and had performance status 0 or 1 (77%). The median age was 61 (range 44-82) years. The percentage of patients alive at 1 year was 36.4% (95% [confidence interval] CI: 24.6-53.8%). The median overall survival was 10.6 months (95% CI: 9.1-14.7). The best overall response rate was 77% (95% CI: 62-89%) with 16% of the patients achieving complete response. The most frequent grade 3 or grade 4 hematological toxicities were neutropenia (64%), thrombocytopenia (36%), and febrile neutropenia (16%). The most common grade 3 or grade 4 nonhematological toxicities were gastrointestinal (30%) and electrolyte changes (23%).

CONCLUSIONS

The addition of exisulind to a standard regimen of carboplatin and etoposide did not improve outcomes compared with historic controls treated with chemotherapy alone. Further evaluation of this regimen in small cell lung cancer is not warranted.

Retinoblastoma tumor suppressor gene expression determines the response to sequential flavopiridol and doxorubicin treatment in small-cell lung carcinoma

PURPOSE

Small-cell lung cancers (SCLC) are defective in many regulatory mechanisms that control cell cycle progression, i.e., functional retinoblastoma protein (pRb). Flavopiridol inhibits proliferation and induces apoptosis in SCLC cell lines. We hypothesized that the sequence flavopiridol followed by doxorubicin would be synergistic in pRb-deficient SCLC cells.

EXPERIMENTAL DESIGN

A H69 pRb-deficient SCLC cell line, H865, with functional pRb and H865 pRb small interfering RNA (siRNA) knockdown cells were used for in vitro and in vivo experiments. The in vivo efficiencies of various sequential combinations were tested using nude/nude athymic mice and human SCLC xenograft models.

RESULTS

Flavopiridol then doxorubicin sequential treatment was synergistic in the pRB-negative H69 cell line. By knocking down pRb with specific siRNA, H865 clones with complete pRb knockdown became sensitive to flavopiridol and doxorubicin combinations. pRb-deficient SCLC cell lines were highly sensitive to flavopiridol-induced apoptosis. pRb-positive H865 cells arrested in G0-G1 with flavopiridol exposure, whereas doxorubicin and all flavopiridol/doxorubicin combinations caused a G2-M block. In contrast, pRb-negative SCLC cells did not arrest in G0-G1 with flavopiridol exposure. Flavopiridol treatment alone did not have an in vivo antitumor effect, but sequential flavopiridol followed by doxorubicin treatment provided tumor growth control and a survival advantage in Rb-negative xenograft models, compared with the other sequential treatments.

CONCLUSIONS

Flavopiridol and doxorubicin sequential treatment induces potent in vitro and in vivo synergism in pRb-negative SCLC cells and should be clinically tested in tumors lacking functional pRB.

Functional interactions of Cu-ATPase ATP7B with cisplatin and the role of ATP7B in the resistance of cells to the drug

Cisplatin is a widely used chemotherapeutic agent for treatment of ovarian, testicular, lung, and stomach cancers. The initial response to the drug is robust; however, tumor cells commonly develop resistance to cisplatin, which complicates treatment. Recently, overexpression of the Cu-ATPase ATP7B in ovary cells was linked to the increased cellular resistance to cisplatin; and the role for Cu-ATPases in the export of cisplatin from cells was proposed. Our results support functional interactions between cisplatin and ATP7B but argue against the active transport through the copper translocation pathway as a mechanism of drug resistance. In hepatocytes, we observed no correlation between the levels of endogenous ATP7B and the resistance of cells to cisplatin. Unlike copper, cisplatin does not induce trafficking of ATP7B in hepatoma cells, neither does it compete with copper in a transport assay. However, cisplatin binds to ATP7B and stimulates catalytic phosphorylation with EC(50) similar to that of copper. Mutations of the first five N-terminal copper-binding sites of ATP7B do not inhibit the cisplatin-induced phosphorylation of ATP7B. In contrast, the deletion of the first four copper-binding sites abolishes the effect of cisplatin on the ATP7B activity. Thus, cisplatin binding to ATP7B and/or general changes in cellular copper homeostasis are likely contributors to the increased resistance to the drug. The link between changes in copper homeostasis and cisplatin resistance was confirmed by treating the Huh7 cells with copper chelator and increasing their resistance to cisplatin.cisplatin.