Tumour pharmacodynamics and circulating cell free DNA in patients with refractory colorectal carcinoma treated with regorafenib.

BACKGROUND: Regorafenib, a multi-kinase inhibitor, is used in the treatment of patients with metastatic colorectal cancer refractory to standard therapy. However, this benefit was limited to 1.4 months improvement in overall survival, with more than half of patients experiencing grade 3 to 4 adverse events. We aim to elucidate the pharmacodynamic effects of regorafenib in metastatic colorectal cancer and discover potential biomarkers that may predict clinical benefit. METHODS: Patients with metastatic colorectal adenocarcinoma refractory to standard therapy with tumours amenable to biopsy were eligible for the study. Regorafenib was administered orally at 160 mg daily for 3 out of 4 weeks with tumour assessment every 2 cycles. Metabolic response was assessed by FDG PET-CT scans (pre-treatment and day 15); paired tumour biopsies (pre-treatment and day 21 post-treatment) were sampled for immunohistochemistry and proteomic profiling analyses. Plasma circulating cell free DNA was quantified serially before and after treatment. RESULTS: There were 2(6%) partial responses out of 35 patients, and 8(23%) patients had stable disease for more than 7 months. Adverse event profile was similar to reported data. Recurrent somatic mutations in K-RAS, PIK3CA and BRAF were detected in plasma circulating cell free DNA in 14 patients; some mutations were not found in archival tumour. Total plasma circulating cell free DNA inversely correlated with progression free survival (PFS), and presence of KRAS mutations associated with shorter PFS. Immunohistochemistry of pre- and post- treatment biopsies showed majority of patients had downregulation of phosphorylated-VEGFR2, podoplanin, phosphorylated-AKT, Ki-67 and upregulation of the MEK-ERK axis, phosphorylated-C-MET, phosphorylated-SRC, phosphorylated-STAT3 and phosphorylated-JUN. Proteomic analysis of fine needle tumour aspirates showed down-regulation of PI3K was associated with longer PFS. CONCLUSION: Plasma circulating cell free DNA may yield potential predictive biomarkers of regorafenib treatment. Downregulation of the PI3K-AKT axis may be an important predictor of clinical benefit.

Correlation of aldo-ketoreductase (AKR) 1C3 genetic variant with doxorubicin pharmacodynamics in Asian breast cancer patients.

AIMS: Aldo-ketoreductases have been implicated in the metabolism of doxorubicin. We sought to assess the influence of AKR1C3 genetic variants on doxorubicin metabolism. METHODS: We sequenced AKR1C3 exon 5 and genotyped seven functional single nucleotide polymorphisms in CBR3, ABCB1 and SLC22A16 involved in doxorubicin pharmacology in 151 Asian breast cancer patients treated with doxorubicin-containing chemotherapy, and correlated these genotypes with doxorubicin pharmacokinetics and pharmacodynamics. RESULTS: Two previously reported AKR1C3 intronic variants, IVS4-212 C>G and IVS4+218 G>A, were detected. The AKR1C3 IVS4-212 GG genotype was associated with significantly lower cycle 1 day 15 leucocyte (mean leucocytes 2.49 ± 1.57 × 10(9) vs. 3.85 ± 3.42 × 10(9) l(-1) , P = 0.007) and neutrophil counts (mean neutrophils 0.70 ± 1.01 × 10(9) vs. 1.56 ± 2.80 × 10(9) l(-1) , P = 0.008) and significant improvement of progression-free survival [PFS, mean PFS 49.0 (95% confidence interval 42.2-55.8) vs. 31.0 (95% confidence interval 20.7-41.2) months, P = 0.017] and overall survival [OS; mean OS 64.4 (95% confidence interval 58.3-70.5) vs. 46.3 (95% confidence interval 35.1-57.5) months, P = 0.006] compared with those carrying at least one C allele. There was no significant association between AKR1C3 IVS4-212 C>G and doxorubicin pharmacokinetics. Of the other seven single nucleotide polymorphisms genotyped, CBR3 G11A correlated with doxorubicinol area under the concentration-time curve and OS, ABCB1 G2677T/A correlated with doxorubicin clearance and platelet toxicity, while ABCB1 IVS26+59 T>G correlated with OS. The AKR1C3 IVS4-212 C

Recent progress and clinical importance on pharmacogenetics in cancer therapy.

Recent advances have provided unprecedented opportunities to identify prognostic and predictive markers of efficacy of cancer therapy. Genetic markers can be used to exclude patients who will not benefit from therapy, exclude patients at high risk of severe toxicity and adjust dosing. Genomic approaches for marker discovery now include genome-wide association studies and tumor DNA sequencing. The challenge is now to select markers for which there is enough evidence to transition them to the clinic. The hurdles include the inherent low frequency of many of these markers, the lengthy validation process through trials, as well as legislative and economic hurdles. Attempts to answer questions about certain markers more quickly have led to an increased popularity of trials with enrichment design, especially in light of the dramatic phase I results seen in recent months. Personalized medicine in oncology is a step closer to reality.

Longitudinal monitoring reveals dynamic changes in circulating tumor cells (CTCs) and CTC-associated miRNAs in response to chemotherapy in metastatic colorectal cancer patients.

We evaluated the changes in CTC count and CTC-associated miRNAs during the course of chemotherapy in patients with metastatic colorectal cancer. Blood samples were collected from 9 metastatic colorectal cancer patients prior to chemotherapy and at every other chemotherapy session during the course of treatment. CTCs were isolated and enumerated using a size-exclusion method (CellSievo, Singapore). CTC-associated miRNAs were isolated using a paper-based, partitioning method, and analyzed using reverse transcription quantitative real-time PCR (MiRXES, Singapore). CTC count trends generally correlated with disease progression defined by radiological measurements and trends in carcinoembryonic antigen (CEA) levels; hence CTC counts may be useful in cases where CEA is not elevated. CTC-associated miRNAs identified were miR-15b, miR-16, miR-19a, miR-21, miR-25, miR-30d, miR-126, miR-185, miR-221, miR-222, and miR-324-5p. The expression of CTC-associated miRNAs did not appear to correlate with CTC count and exhibited inter-individual heterogeneity. This pilot study suggests that analysis of CTC changes during the course of treatment may be useful in monitoring response to therapy in metastatic colorectal cancer.

Conversion Surgery Post-Intraperitoneal Paclitaxel and Systemic Chemotherapy for Gastric Cancer Carcinomatosis Peritonei. Are We Ready?

Peritoneal metastasis is common in gastric cancer. It is difficult to treat and carries a poor prognosis. Intraperitoneal (IP) delivery of chemotherapy can attain a higher drug exposure in the peritoneal cavity but with reduced systemic toxicity. Therefore, we hypothesized that IP paclitaxel with systemic chemotherapy would be clinically beneficial for gastric cancer with peritoneal metastases. Patients with unresectable and/or recurrent gastric adenocarcinoma with peritoneal dissemination and/or positive peritoneal washing cytology were recruited. They underwent eight cycles of IP paclitaxel and systemic XELOX. The primary endpoint was 1-year overall survival rate and secondary endpoints were safety, response rate, and peritoneal cytological response. Patients who subsequently had no distant metastases and two consecutive negative peritoneal cytologies underwent conversion gastrectomy if there was no macroscopic evidence of peritoneal disease at diagnostic laparoscopy. Twenty-two patients were enrolled, receiving at least one cycle of IP paclitaxel at the time of reporting (data cutoff-March 11, 2016). The median number of cycles was 7.5. The median overall survival was 18.8 months, and the 1-year survival rate was 72.2%. One patient died of neutropenic sepsis. Of 19 evaluable patients with measurable disease, 7 (36.8%) achieved PR, 8 (42.1%) achieved SD, and 4 (21.1%) experienced PD. Peritoneal cytology turned negative in 11 of 17 (64.7%) patients. Six patients underwent conversion gastrectomy (4 R0, 2 R1) with a median survival of 21.6 months (range = 8.7-29.9 months). XELOX and IP paclitaxel appears to be an effective regimen in gastric cancer with peritoneal metastases. Conversion gastrectomy may be considered in patients with a favorable response.

Phenotyping of UGT1A1 Activity Using Raltegravir Predicts Pharmacokinetics and Toxicity of Irinotecan in FOLFIRI.

BACKGROUND: Irinotecan toxicity correlates with UGT1A1 activity. We explored whether phenotyping UGT1A1 using a probe approach works better than current genotyping methods. METHODS: Twenty-four Asian cancer patients received irinotecan as part of the FOLFIRI regimen. Subjects took raltegravir 400 mg orally and intravenous midazolam 1 mg. Pharmacokinetic analyses were performed using WinNonLin and NONMEM. Genomic DNA was isolated and screened for the known genetic variants in UGT1A1 and CYP3A4/5. RESULTS: SN-38G/SN-38 AUC ratio correlated well with Raltegravir glucuronide/ Raltegravir AUC ratio (r = 0.784 p<0.01). Midazolam clearance correlated well with irinotecan clearance (r = 0.563 p<0.01). SN-38 AUC correlated well with Log10Nadir Absolute Neutrophil Count (ANC) (r = -0.397 p<0.05). Significant correlation was found between nadir ANC and formation rate constant of raltegravir glucuronide (r = 0.598, P<0.005), but not UGT1A1 genotype. CONCLUSION: Raltegravir glucuronide formation is a good predictor of nadir ANC, and can predict neutropenia in East Asian patients. Prospective studies with dose adjustments should be done to develop raltegravir as a probe to optimize irinotecan therapy. TRIAL REGISTRATION: Clinicaltrials.gov NCT00808184.

Phase Ib/II randomized, open-label study of doxorubicin and cyclophosphamide with or without low-dose, short-course sunitinib in the pre-operative treatment of breast cancer.

BACKGROUND: Prolonged anti-angiogenic therapy destroys tumor vasculature, whereas vascular-normalizing doses may enhance intra-tumoral drug delivery. We hypothesize that low-dose, short-course sunitinib normalizes vasculature, enhancing chemotherapy efficacy. PATIENTS AND METHODS: In phase Ib, treatment-naïve breast cancer patients received four cycles of pre-operative doxorubicin/cyclophosphamide, with sunitinib before each cycle. The optimal dose of sunitinib leading to tumor vessel normalization on immunohistochemistry was identified. In phase II, subjects were randomized to chemotherapy alone or chemotherapy plus sunitinib at the recommended phase II dose (RP2D). Primary endpoint was pathological complete response (pCR) rate. Tumor and functional imaging biomarkers were evaluated serially. RESULTS: In phase Ib (n=9), sunitinib 12.5 mg daily for 7 days before each chemotherapy was established as RP2D. In phase II, patients receiving chemotherapy plus sunitinib (n=24) had similar pCR rates (5.0% versus 4.3%, p=1.00), but a higher incidence of chemotherapy dose delays (33.3% versus 8.7%, p=0.04), compared to those receiving chemotherapy alone (n=25). The addition of sunitinib to chemotherapy significantly increased vascular normalization index (VNI) and decreased lymphatic vessel density (D2-40) on immunohistochemistry [VNI:25.50±27.94% versus 49.29±31.84%, p=0.034; D2-40:3.29±2.70 versus 1.29±1.54, p=0.014, baseline versus post-cycle 1], and improved perfusion on DCE-MRI (Ktrans:12.6±9.6 mL/100 g/min versus 16.3±10.7 mL/100 g/min, baseline versus post-cycle 1, p=0.015). Conversely, immunohistochemical and DCE-MRI parameters were not significantly altered by chemotherapy alone. CONCLUSION: Low-dose, short-course sunitinib prior to anthracycline-based chemotherapy in breast cancer patients did not improve pCR and increased chemotherapy dose delays. However, the addition of sunitinib induced compelling pharmacodynamic evidence of vascular normalization. Further studies with alternative cytotoxic regimens should be explored.

Improving Wait Times for Elective Chemotherapy Through Pre-Preparation: A Quality-Improvement Project at the National University Cancer Institute of Singapore.

PURPOSE: Cancer treatment occurs predominantly in the outpatient setting. Long wait times for chemotherapy lead to increased dissatisfaction, inefficient use of chemotherapy chairs, and compromised safety when delays result in treatment beyond operation hours. For patients who have undergone review with the necessary investigations by their oncologists on a prior day, a long wait time is more frustrating, because the sole purpose of their visit is for chemotherapy (termed elective chemotherapy). PATIENTS AND METHODS: From February 2013 to September 2013, we conducted a clinical practice improvement program project to reduce wait times for elective chemotherapy and identified late submission of prescriptions, long drug preparation time, and pharmacy review of prescriptions as the main causes of delay in our center. We formulated a workflow to pre-prepare selected chemotherapy up to 1 day before appointments. Selection was based on shelf life, cost, recyclability, and need for premedication. Patients were triaged by telephone before their appointment before pre-preparation. Participation was voluntary, with patients required to consent for liability for cost in event of wastage. RESULTS: Average wait time for chemotherapy was significantly improved by 66% from 65.7 (median, 60; range, 5 to 301) to 22.4 minutes (median, 20; range, 0 to 80 minutes; P < .001). There were no wastages during this period, and treatment for elective patients could start as soon as the center opened if their drugs were pre-prepared the day before. CONCLUSION: Pre-preparation of chemotherapy, together with effective phone triaging, is an effective way to reduce chemotherapy wait time.

Targeted therapy at the end of life in advanced cancer patients.

OBJECTIVE: We describe the use of systemic therapy in advanced cancer patients admitted to an acute care hospital, with a focus on targeted therapy. We aim to spotlight the utilization of targeted agents in the last months of life. METHODS: Adult patients (N=252) with advanced solid tumors who died as inpatients in the National University Hospital, Singapore, were included in this retrospective study. Patients' demographic and clinical data were extracted from hospital records. Information on systemic therapy was extracted from the time of diagnosis and all other data limited to the last three months before death. RESULTS: 187 adult patients received palliative systemic therapy from the time of diagnosis, of which 125 (66.8%) received it within three months of death. Of patients receiving only nontargeted systemic treatment (n=106), 60 (56.6%) and 26 (24.5%) received it within three months and one month of death respectively. Comparatively, 81 patients received palliative targeted systemic therapy, of which 65 (80.3%) and 40 (49.4%) had treatment within three months and one month of death respectively (p=0.001 and p<0.001). Targeted therapy was first initiated in the last three months of life in 38 patients. Oral agents targeting epidermal growth factor receptor (lung cancer patients) and vascular endothelial growth factor receptor (non-lung cancer patients) pathways were commonly employed. Lung cancer patients were more likely to have targeted therapy as their last line of systemic therapy: 26/54 lung cancer patients compared with 29/133 non-lung cancer patients (48.1% versus 21.8%, p<0.001). CONCLUSIONS: Targeted therapy is used in more than half of patients who received systemic therapy within three months of death. The degree to which these agents are being utilized near the end of life suggests the need to reexamine the risk/benefit profile of targeted therapy for this population, and the decision-making process around their use.

Germline genetic testing to predict drug response and toxicity in oncology--reality or fiction?

In addition to 6-mercaptopurine, 5-fluorouracil and irinotecan, the United States Food and Drug Administration (US FDA) has recently recommended label change for tamoxifen, to include pharmacogenetic information on treatment outcome. With the increasing availability of pharmacogenetic testing, on germline as well as somatic mutations, oncologists are now able to identify individuals at risk of severe treatment toxicity or poor treatment response. However, there are still knowledge gaps to fill before rationalised therapy based on pharmacogenetics can be fully integrated into clinical practice. This review provides an overview on the application of pharmacogenetic testing for germ line mutations in oncology to predict response and toxicity.