Cost of Medical Care of Patients with Advanced Serious Illness in Singapore (COMPASS): prospective cohort study protocol.

BACKGROUND: Advanced cancer significantly impacts quality of life of patients and families as they cope with symptom burden, treatment decision-making, uncertainty and costs of treatment. In Singapore, information about the experiences of advanced cancer patients and families and the financial cost they incur for end-of-life care is lacking. Understanding of this information is needed to inform practice and policy to ensure continuity and affordability of care at the end of life. The primary objectives of the Cost of Medical Care of Patients with Advanced Serious Illness in Singapore (COMPASS) cohort study are to describe changes in quality of life and to quantify healthcare utilization and costs of patients with advanced cancer at the end of life. Secondary objectives are to investigate patient and caregiver preferences for diagnostic and prognostic information, preferences for end-of-life care, caregiver burden and perceived quality of care and to explore how these change as illness progresses and finally to measure bereavement adjustment. The purpose of this paper is to present the COMPASS protocol in order to promote scientific transparency. METHODS: This cohort study recruits advanced cancer patients (n = 600) from outpatient medical oncology clinics at two public tertiary healthcare institutions in Singapore. Patients and their primary informal caregiver are surveyed every 3 months until patients' death; caregivers are followed until 6 months post patient death. Patient medical and billing records are obtained and merged with patient survey data. The treating medical oncologists of participating patients are surveyed to obtain their beliefs regarding care delivery for the patient. DISCUSSION: The study will allow combination of self-report, medical, and cost data from various sources to present a comprehensive picture of the end-of-life experience of advanced cancer patients in a unique Asian setting. This study is responsive to Singapore's National Strategy for Palliative Care which aims to identify opportunities to meet the growing need for high quality care for Singapore's aging population. Results will also be of interest to policy makers and researchers beyond Singapore who are interested to understand and improve the end-of-life experience of cancer patients. TRIAL REGISTRATION: NCT02850640 (Prospectively registered on June 9, 2016).

Structural, biochemical, and clinical characterization of epidermal growth factor receptor (EGFR) exon 20 insertion mutations in lung cancer.

Epidermal growth factor receptor (EGFR) gene mutations (G719X, exon 19 deletions/insertions, L858R, and L861Q) predict favorable responses to EGFR tyrosine kinase inhibitors (TKIs) in advanced non-small cell lung cancer (NSCLC). However, EGFR exon 20 insertion mutations (~10% of all EGFR mutations) are generally associated with insensitivity to available TKIs (gefitinib, erlotinib, and afatinib). The basis of this primary resistance is poorly understood. We studied a broad subset of exon 20 insertion mutations, comparing in vitro TKI sensitivity with responses to gefitinib and erlotinib in NSCLC patients, and found that most are resistant to EGFR TKIs. The crystal structure of a representative TKI-insensitive mutant (D770_N771insNPG) reveals an unaltered adenosine triphosphate-binding pocket, and the inserted residues form a wedge at the end of the C helix that promotes the active kinase conformation. Unlike EGFR-L858R, D770_N771insNPG activates EGFR without increasing its affinity for EGFR TKIs. Unexpectedly, we find that EGFR-A763_Y764insFQEA is highly sensitive to EGFR TKIs in vitro, and patients whose NSCLCs harbor this mutation respond to erlotinib. Analysis of the A763_Y764insFQEA mutant indicates that the inserted residues shift the register of the C helix in the N-terminal direction, altering the structure in the region that is also affected by the TKI-sensitive EGFR-L858R. Our studies reveal intricate differences between EGFR mutations, their biology, and their response to EGFR TKIs.

Gemcitabine and platinum pathway pharmacogenetics in Asian breast cancer patients.

BACKGROUND/AIM: Gemcitabine/carboplatin is efficacious in breast cancer but results in significant hematologic toxicities. We employed a multi-gene approach to identify variants to predict its toxicities. PATIENTS AND METHODS: Twenty-six gemcitabine and platinum-based DNA repair pathway polymorphisms were correlated with gemcitabine pharmacokinetics, hematologic toxicities, response and survival in 41 Asian breast cancer patients receiving gemcitabine/carboplatin. RESULTS: The combined effects of solute carrier family (SLC)28A1+1528C>T and thymidylate synthetase (TYMS)+1494del6 significantly influenced hematologic toxicities: 89% of patients who possessed either SLC28A1+1528TT or TYMS+1494ins6/ins6 (n=9) developed grade 4 thrombocytopenia, versus 14% with neither genotype (n=29; p<0.001). In concordance, all patients who possessed either genotype developed grade 3/4 neutropenia, compared to 38% with neither genotype (p=0.001). None of the other genetic variants analyzed correlated with drug pharmacokinetics and pharmacodynamics. CONCLUSION: Approximately one-quarter of our Asian cohort carried SLC28A1+1528TT or TYMS+1494ins6/ins6, which are associated with increased myelotoxicity from gemcitabine/carboplatin. This has potential utility in treatment selection and genotype-based dosing strategies.

Impact of UDP-gluconoryltransferase 2B17 genotype on vorinostat metabolism and clinical outcomes in Asian women with breast cancer.

OBJECTIVES: Vorinostat, a histone deacetylase inhibitor being actively evaluated in solid tumors, is metabolized by UGT2B17. UGT2B17 null genotype (UGT2B17*2) has been shown in vitro to reduce UGT2B17 activity. This variant is common in Asians but rare in Caucasians, and we studied its impact on vorinostat pharmacokinetics and pharmacodynamics in a clinical study in Asian patients with metastatic breast cancer. METHODS: Eligible patients received 400 mg of vorinostat monotherapy daily in a lead-in phase I followed by a phase II study. Patients were genotyped for UGT2B17*2, which was correlated with vorinostat pharmacokinetics and clinical outcomes. RESULTS: Twenty-six patients were treated with no complete response, one partial response, six stable disease lasting for 12 weeks or more, and 19 progressive disease. Sixteen patients (62%) were UGT2B17*2 homozygotes and had significantly lower mean area under the curve ratio of vorinostat-O-glucuronide/vorinostat (1.84 vs. 2.51 on day 1, P=0.02; 1.63 vs. 2.38 on day 15, P=0.028), and trended toward having higher vorinostat area under the curve (399.02 vs. 318.40, P=0.188), more serious adverse events (31 vs. 0%, P=0.121), higher clinical benefit rate (40 vs. 10%, P=0.179), and longer median progression-free survival (3.0 vs. 1.5 months, P=0.087) than patients with at least one wild-type allele. CONCLUSION: UGT2B17*2 genotype reduces vorinostat glucuronidation and may increase vorinostat efficacy and toxicity. These observations are important in the development of vorinostat, and may have clinical implications on other cancer and noncancer drugs that are UGT2B17 substrates such as exemestane and ibuprofen.

Ethnic differences in survival outcome in patients with advanced stage non-small cell lung cancer: results of a meta-analysis of randomized controlled trials.

INTRODUCTION: Although interethnic differences in survival to cytotoxic chemotherapy in patients with non-small cell lung cancer exist, an analysis of survival outcomes based on ethnicity has not yet been fully evaluated systematically using large patient cohorts. Furthermore, recent trial results may be confounded by the use of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). METHODS: A meta-analysis was performed using trials identified through MEDLINE. Summary data on median overall survival (OS), time to progression, progression-free survival, and overall response rate (ORR) were collected from randomized controlled trials. Outcomes were compared between Asian and Caucasian studies. RESULTS: Of the 1182 citations identified, 391 treatment arms (Asian 90 and Caucasian 301) were analyzed. The median OS and ORR in Asian and Caucasian studies for all chemotherapy regimens was 10.1 and 8.0 months (p < 0.001) and 32.2 and 25.9% (p < 0.001), respectively. The median OS in Asian and Caucasian studies for monotherapy, platinum doublets, and three drugs or more combination was 9.9 and 6.8 months, 10.4 and 8.6 months, and 9.4 and 8.0 months, respectively (all p < 0.001). In studies published pre-EGFR TKI, the median OS and ORR in Asian and Caucasian studies for all chemotherapy regimens was 9.1 versus 7.3 months (p < 0.001), respectively, and 29.0 and 23.0% (p < 0.006), respectively. The median OS in Asian and Caucasian studies for monotherapy, platinum doublets, and three drugs or more combination pre-EGFR TKI was 8.9 and 6.5 months (p < 0.005), 9.1 and 7.5 months (p < 0.001), and 9.3 and 7.6 months (p < 0.003), respectively. In third-generation platinum doublets, the median OS in Asian and Caucasian studies was 11.3 and 9.5 months (p < 0.001), respectively, and ORR was 35.0 and 29.8% (p < 0.001), respectively. CONCLUSION: Ethnic differences in survival and response rate to chemotherapy exist and should be considered in clinical trial designs especially in the global context.

Erlotinib at a dose of 25 mg daily for non-small cell lung cancers with EGFR mutations.

PURPOSE: The tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib are effective in non-small cell lung cancers (NSCLCs) with epidermal growth factor receptor (EGFR) gene mutations. The usual clinical dose of gefitinib (250 mg/d) is only one third of its maximum tolerated dose, whereas the dose of erlotinib (150 mg/d) is at its maximum tolerated dose. In NSCLC cell lines, both TKIs have similar micromolar inhibitory concentrations. We explored whether erlotinib at 25 mg/d (trough serum concentration similar to gefitinib 250 mg/d) would be efficacious in EGFR-mutated NSCLC. METHODS: To study the inhibitory concentrations of gefitinib and erlotinib, we exposed EGFR-mutated cell lines (HCC827, H3255, PC-9, and H1975) to increasing concentrations of these TKIs. Further on, we performed a retrospective evaluation of seven patients with advanced EGFR-mutated (exon 19 deletions and L858R) NSCLC that were given erlotinib at 25 mg/d as their first EGFR TKI. RESULTS: Gefitinib and erlotinib generated similar inhibitory curves across our panel of EGFR-mutated NSCLC cell lines with overlapping mean 50% inhibitory concentration 95% confidence intervals for HCC827, PC-9, and H1975. Both drugs also displayed a high degree of correlation in mean 50% inhibitory concentration (Pearson's r = 0.99, p = 0.0417). Of the seven patients, five patients (71.5%) had partial responses to erlotinib 25 mg/d. Median progression-free survival was 17 months (95% confidence interval, 6-35 months). Toxicities were minimal, with only two (28.5%) patients having a rash and none experiencing (0%) diarrhea. CONCLUSIONS: In NSCLC cell lines, gefitinib and erlotinib have similar inhibitory profiles. In patients with NSCLC and EGFR-activating mutations, a dose of erlotinib 25 mg/d (equivalent to gefitinib 250 mg/d) leads to impressive response rates and progression-free survival similar to the growing experience with the approved doses of gefitinib (250 mg/d) and erlotinib (150 mg/d). Identifying prospectively the lowest and clinically active dose ranges of erlotinib and gefitinib will help further to personalize care for patients with tumors harboring EGFR mutations.

Phase II study of gemcitabine and carboplatin in metastatic breast cancers with prior exposure to anthracyclines and taxanes.

BACKGROUND: Patients with metastatic breast cancer (MBC) are usually exposed to both anthracyclines and taxanes during neoadjuvant or adjuvant treatment of primary breast cancer or during initial therapy of MBC. We investigate the combination of gemcitabine and carboplatin in MBC with prior exposure to both anthracyclines and taxanes. PATIENTS AND METHODS: MBC patients previously treated with anthracyclines and taxanes were enrolled in a single tertiary center phase II study. Treatment consisted of gemcitabine (1,000 mg/m(2) I.V on days 1 and 8) and carboplatin (AUC 5 I.V on day 1) administered every 3 weeks. Results 41 patients were recruited. Objective response rate was 39% including 1 complete response (2%) and 15 partial responses (37%). Twelve patients (29%) had stable disease. Median time to progression was 4.6 months (95% CI 3.3-5.9 months) and median overall survival 10.5 months (95% CI 7.6-13.4 months). Grade 3 & 4 hematological toxicities included neutropenia (58%), febrile neutropenia (15%), anemia (12%) and thrombocytopenia (49%), including 7% who required platelet transfusions. Non-hematological toxicity was rarely severe. 56% of patients required at least one dose reduction; the mean relative dose intensity for gemcitabine and carboplatin were 0.82 (range 0.5-1.0) and 0.95 (range 0.75-1.00) respectively, with no difference in dose intensity between responders and non-responders. CONCLUSION: Gemcitabine combined with carboplatin has promising efficacy in MBC with prior treatment with anthracyclines and taxanes but has significant haematological toxicities requiring dose modifications. The regimen may be modified to gemcitabine 800 mg/m(2) days 1 and 8 to improve tolerability.

The role of epidermal growth factor receptor tyrosine kinase inhibitors in the treatment of advanced stage non-small cell lung cancer.

The epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) like erlotinib and gefitinib have been extensively studied. Multiple randomized trials have evaluated the role of EGFR TKIs in advanced stage non-small cell lung cancer (NSCLC) as a monotherapy in the first line, or subsequent lines of therapy, and in the first line in the maintenance setting or in combination with chemotherapy. Most of these trials showed positive results in particular for selected patients with specific clinical characteristic and somatic activating mutation of EGFR. A further understanding of the mechanism of primary and secondary resistance has led to the development of promising novel agents designed to overcome resistance to EGFR.

Chemotherapy-induced tumor gene expression changes in human breast cancers.

OBJECTIVE: Studying chemotherapy-induced gene expression changes in vivo, which could provide insights into mechanisms of chemotherapy resistance. METHODS: We analyzed and compared tumor gene expression changes of about 38 500 genes before and 3 weeks after doxorubicin or docetaxel treatment in 47 breast cancer patients. RESULTS: By using the median expression level of each probe set as the parameter, less than 5% of genes were upregulated or downregulated by more than 50% after treatment with either drug. Doxorubicin and docetaxel concordantly induced 251 genes predominantly involved in protein and macromolecule metabolism (upregulated), and cell cycle and DNA/RNA metabolism (downregulated). Doxorubicin treatment resulted in coregulation of a cluster of 345 probe sets involved in focal adhesion, Jak-Stat signaling pathway, cell adhesion molecules, and natural killer cell mediated cytotoxicity, whereas docetaxel treatment resulted in coregulation of a cluster of 448 probe sets involved in focal adhesion, neurodegenerative disorders, sphingolipid metabolism, and cell cycle. Tumors that were intrinsically sensitive or resistant to doxorubicin or docetaxel evoked distinct gene expression changes in response to the drug; doxorubicin-resistant tumors upregulated genes that were enriched for ErbB signaling, ubiquitin-mediated proteolysis, TGF-beta signaling, and MAP-kinase signaling pathways, whereas docetaxel-resistant tumors upregulated genes that were enriched for focal adhesion and regulation of actin cytoskeleton. The drug-specific tumor gene expression changes were validated in independent in-vitro and in-vivo datasets. CONCLUSION: Gene expression alterations of breast cancer were specific to doxorubicin and docetaxel treatment, and yielded mechanistic insights into resistance to either drug. Gene expression analysis provides more global perspectives on resistance pathways that could be exploited for therapeutic selection.