The Pancreatic Cancer Early Detection (PRECEDE) Study is a Global Effort to Drive Early Detection: Baseline Imaging Findings in High-Risk Individuals.

BACKGROUND: Pancreatic adenocarcinoma (PC) is a highly lethal malignancy with a survival rate of only 12%. Surveillance is recommended for high-risk individuals (HRIs), but it is not widely adopted. To address this unmet clinical need and drive early diagnosis research, we established the Pancreatic Cancer Early Detection (PRECEDE) Consortium. METHODS: PRECEDE is a multi-institutional international collaboration that has undertaken an observational prospective cohort study. Individuals (aged 18-90 years) are enrolled into 1 of 7 cohorts based on family history and pathogenic germline variant (PGV) status. From April 1, 2020, to November 21, 2022, a total of 3,402 participants were enrolled in 1 of 7 study cohorts, with 1,759 (51.7%) meeting criteria for the highest-risk cohort (Cohort 1). Cohort 1 HRIs underwent germline testing and pancreas imaging by MRI/MR-cholangiopancreatography or endoscopic ultrasound. RESULTS: A total of 1,400 participants in Cohort 1 (79.6%) had completed baseline imaging and were subclassified into 3 groups based on familial PC (FPC; n=670), a PGV and FPC (PGV+/FPC+; n=115), and a PGV with a pedigree that does not meet FPC criteria (PGV+/FPC-; n=615). One HRI was diagnosed with stage IIB PC on study entry, and 35.1% of HRIs harbored pancreatic cysts. Increasing age (odds ratio, 1.05; P<.001) and FPC group assignment (odds ratio, 1.57; P<.001; relative to PGV+/FPC-) were independent predictors of harboring a pancreatic cyst. CONCLUSIONS: PRECEDE provides infrastructure support to increase access to clinical surveillance for HRIs worldwide, while aiming to drive early PC detection advancements through longitudinal standardized clinical data, imaging, and biospecimen captures. Increased cyst prevalence in HRIs with FPC suggests that FPC may infer distinct biological processes. To enable the development of PC surveillance approaches better tailored to risk category, we recommend adoption of subclassification of HRIs into FPC, PGV+/FPC+, and PGV+/FPC- risk groups by surveillance protocols.

Synthetic lethal interaction between oncogenic KRAS dependency and STK33 suppression in human cancer cells.

An alternative to therapeutic targeting of oncogenes is to perform "synthetic lethality" screens for genes that are essential only in the context of specific cancer-causing mutations. We used high-throughput RNA interference (RNAi) to identify synthetic lethal interactions in cancer cells harboring mutant KRAS, the most commonly mutated human oncogene. We find that cells that are dependent on mutant KRAS exhibit sensitivity to suppression of the serine/threonine kinase STK33 irrespective of tissue origin, whereas STK33 is not required by KRAS-independent cells. STK33 promotes cancer cell viability in a kinase activity-dependent manner by regulating the suppression of mitochondrial apoptosis mediated through S6K1-induced inactivation of the death agonist BAD selectively in mutant KRAS-dependent cells. These observations identify STK33 as a target for treatment of mutant KRAS-driven cancers and demonstrate the potential of RNAi screens for discovering functional dependencies created by oncogenic mutations that may enable therapeutic intervention for cancers with "undruggable" genetic alterations.

Molecular Pathogenesis of Cholangiocarcinoma: Implications for Disease Classification and Therapy.

Cholangiocarcinomas are an aggressive group of heterogeneous malignancies that affect over 210,000 individuals globally each year. Their incidence is rising, particularly in Western countries. Traditionally, cholangiocarcinomas are classified based on anatomic location of the tumor and are treated with similar cytotoxic chemotherapy despite significant molecular and genomic differences. With the rise of genetic and molecular sequencing, several driver mutations have been identified and targeted as novel therapeutic approaches. The most common genomic alterations include changes in FGFR2, IDH1, KRAS, BRAF, HER2, and the tumor suppressor p53. In addition, increased understanding of the cellular and molecular constituents of the tumor microenvironment (TME) has created opportunities for further novel therapeutic approaches. New strategies using combination therapies targeting driver mutations and various components of the TME hold promise for improved patient outcomes. This review covers the evolving molecular and therapeutic landscape of cholangiocarcinoma.

A phase 2 clinical trial of the heat shock protein 90 (HSP 90) inhibitor ganetespib in patients with refractory advanced esophagogastric cancer.

Subsets of esophagogastric (EG) cancers harbor genetic abnormalities, including amplification of HER2, MET, or FGFR2 or mutations in PIK3CA, EGFR, or BRAF. Ganetespib which is a novel triazolone heterocyclic inhibitor of HSP90, is a potentially biologically rational treatment strategy for advanced EG cancers with these gene amplification. This multicenter, single-arm phase 2 trial enrolled patients with histologically confirmed advanced EG cancer with progression on at least one line of systemic therapy. Patients received Ganetespib 200 mg/m2 IV on Days 1, 8, and 15 of a 28-day cycle. The primary endpoint was overall response rate (ORR). Secondary endpoints included: Progression Free Survival (PFS); to correlate the presence of HSP clients with ORR and PFS; evaluating the safety, tolerability and adverse events profile. In this study 26 eligible patients mainly: male 77%, median age 64 years were enrolled. The most common drug-related adverse events were diarrhea (77%), fatigue (65%), elevated ALKP (42%), and elevated AST (38%). The most common grade 3/4 AEs included: leucopenia (12%), fatigue (12%), diarrhea (8%), and elevated ALKP (8%). The ORR of 4% reflects the single patient of 26 who had a complete response and stayed on treatment for more than seventy (70) months. Median PFS and OS was 61 days (2.0 months), 94 days (3.1 months) respectively. Ganetespib showed manageable toxicity. While the study was terminated early due to insufficient evidence of single-agent activity, the durable CR and 2 minor responses suggest that there may be a subset of EG patients who could benefit from this drug.

Molecular Testing to Optimize and Personalize Decision Making in the Management of Colorectal Cancer.

Recent improvements in our understanding of the biology of colorectal cancer have led to the identification of several important prognostic and predictive markers of disease-associated risk and treatment response for the individual patient. Proper utilization of these biomarkers can enable physicians to tailor therapeutic strategies to maximize the likelihood of response and minimize treatment toxicity. In the management of colorectal cancer, tremendous progress has been made in the development of strategies for immune checkpoint inhibition; in refinement of agents and approaches used in targeted therapy; and in techniques for molecular subtyping of tumor samples that have identified patient subgroups with clinically relevant cellular differences potentially affecting clinical management and treatment outcome. In this article, we discuss several of the commonly tested markers in colorectal cancer-including microsatellite instability, RAS/RAF, DPD, HER2, UTG1A1, TS, and Immunoscore-and highlight their prevalence, prognostic and predictive value, and current role in the overall treatment paradigm.

A phase I and pharmacokinetic study of ganetespib (STA-9090) in advanced hepatocellular carcinoma.

BACKGROUND: Ganetespib (STA-9090) is an Hsp90 inhibitor that downregulates VEGFR, c-MET, HER2, IGF-IR, EGFR, and other Hsp90 client proteins involved in hepatocarcinogenesis, thereby making it an attractive therapy for HCC. This Phase I study was performed to establish the safety, tolerability, recommended Phase 2 dose (RP2D), and preliminary clinical activity of ganetespib in previously treated patients with advanced HCC. METHODS: Patients with advanced HCC, Child-Pugh A cirrhosis, progression on or intolerance to sorafenib, and ECOG PS ≤ 1 were enrolled in a standard 3x3 dose escalation study at doses of 100 mg/m(2), 150 mg/m(2), and 200 mg/m(2) IV given on days 1, 8, and 15 of each 28-day cycle. Objective response by RECIST version 1.1 criteria was evaluated by CT/MRI every 8 weeks. RESULTS: Fourteen patients were enrolled in this trial and received at least one dose of the study drug. Of the 14 patients: median age, 57 years old; male 71 %; Asian 36 %; HCC etiology (HBV 36 %, HCV 43 %, Hemachromatosis 7 %, unknown 21 %); Child Pugh Class (A 93 %, B 7 %); median number of prior treatments 2; median baseline AFP 70.1 ng/mL. The RP2D was determined to be 200 mg/m(2). The most commonly seen AEs were diarrhea (93 %), fatigue (71 %), AST elevation (64 %), and hyperglycemia (64 %). The most common Gr 3/4 AEs were hyperglycemia (21 %) and lipasemia (21 %). One (7 %) patient had a fatal AE, septic shock, within 30 days of receiving the study drug. One dose-limiting toxicity, grade 3 lipasemia, was observed at the 100 mg/m(2) dose. Pharmacokinetics studies showed a t1/2, CL, Tmax, and Vss of 6.45 h, 48.28 L/h (25.56 L/h/m(2)), 0.76 h, and 191 L (100.4 L/m(2)), respectively. No objective responses were seen; one patient (7 %) had stable disease at 16 weeks. Median time to progression was 1.8 months, and median overall survival was 7.2 months. CONCLUSION: Ganetespib had a manageable safety profile in patients with advanced HCC who had progressed on at least one line of systemic therapy. The pharmacokinetic profile showed that ganetespib exposure in patients with mild hepatic dysfunction is similar to that seen in patients with normal liver function. Ganetespib showed limited clinical benefit in patients with advanced HCC in this phase I trial.

Systematic RNA interference reveals that oncogenic KRAS-driven cancers require TBK1.

The proto-oncogene KRAS is mutated in a wide array of human cancers, most of which are aggressive and respond poorly to standard therapies. Although the identification of specific oncogenes has led to the development of clinically effective, molecularly targeted therapies in some cases, KRAS has remained refractory to this approach. A complementary strategy for targeting KRAS is to identify gene products that, when inhibited, result in cell death only in the presence of an oncogenic allele. Here we have used systematic RNA interference to detect synthetic lethal partners of oncogenic KRAS and found that the non-canonical IkappaB kinase TBK1 was selectively essential in cells that contain mutant KRAS. Suppression of TBK1 induced apoptosis specifically in human cancer cell lines that depend on oncogenic KRAS expression. In these cells, TBK1 activated NF-kappaB anti-apoptotic signals involving c-Rel and BCL-XL (also known as BCL2L1) that were essential for survival, providing mechanistic insights into this synthetic lethal interaction. These observations indicate that TBK1 and NF-kappaB signalling are essential in KRAS mutant tumours, and establish a general approach for the rational identification of co-dependent pathways in cancer.

Mutational analysis and clinical correlation of metastatic colorectal cancer.

BACKGROUND: Early identification of mutations may guide patients with metastatic colorectal cancer toward targeted therapies that may be life prolonging. The authors assessed tumor genotype correlations with clinical characteristics to determine whether mutational profiling can account for clinical similarities, differences, and outcomes. METHODS: Under Institutional Review Board approval, 222 patients with metastatic colon adenocarcinoma (n = 158) and rectal adenocarcinoma (n = 64) who underwent clinical tumor genotyping were reviewed. Multiplexed tumor genotyping screened for >150 mutations across 15 commonly mutated cancer genes. The chi-square test was used to assess genotype frequency by tumor site and additional clinical characteristics. Cox multivariate analysis was used to assess the impact of genotype on overall survival. RESULTS: Broad-based tumor genotyping revealed clinical and anatomic differences that could be linked to gene mutations. NRAS mutations were associated with rectal cancer versus colon cancer (12.5% vs 0.6%; P < .001) and with age ≥56 years (7% vs 0.9%; P = .02). Conversely, v-raf murine sarcoma viral oncogene homolog B (BRAF) mutations were associated with colon cancer (13% vs 3%; P = .024) and older age (15.8% vs 4.6%; P = .006). TP53 mutations were associated with rectal cancer (30% vs 18%; P = .048), younger age (14% vs 28.7%; P = .007), and men (26.4% vs 14%; P = .03). Lung metastases were associated with PIK3CA mutations (23% vs 8.7%; P = .004). Only mutations in BRAF were independently associated with decreased overall survival (hazard ratio, 2.4; 95% confidence interval, 1.09-5.27; P = .029). CONCLUSIONS: The current study suggests that underlying molecular profiles can differ between colon and rectal cancers. Further investigation is warranted to assess whether the differences identified are important in determining the optimal treatment course for these patients.

Long-term outcomes of neoadjuvant chemotherapy before chemoradiation for locally advanced pancreatic cancer.

BACKGROUND: Neoadjuvant chemotherapy before chemoradiation therapy (CRT) may improve outcomes for patients with locally advanced pancreatic cancer, but optimal management remains controversial, and prior reports have limited follow-up. METHODS: Seventy consecutive patients with unresectable (n = 46) or borderline resectable (n = 24) locally advanced pancreatic cancer were treated with CRT from 2005 to 2009. Patients typically received 50.4 grays in 28 fractions (91%) with concurrent 5-fluorouracil (84%) or capecitabine (14%). Forty patients received CRT alone, and 30 patients received neoadjuvant chemotherapy before CRT for a median of 4 months, typically gemcitabine (93%). All patients without progression after neoadjuvant chemotherapy were offered CRT. RESULTS: Median follow-up was 14.2 months (range, 3-57 months). Fifty-three percent of patients in the CRT group versus 83% in the neoadjuvant chemotherapy before CRT group had unresectable tumors at diagnosis; after completion of CRT, 20% of patients in both groups underwent resection. Compared with CRT alone, the neoadjuvant chemotherapy before CRT group demonstrated improved median overall survival (OS; 18.7 vs 12.4 months; P = .02) and progression-free survival (11.4 vs 6.7 months; P = .02). On multivariate analysis, receipt of neoadjuvant chemotherapy (adjusted hazard ratio [HR], 0.49; 95% CI, 0.28-0.87; P = .02) and surgical resection (adjusted HR, 0.38; 95% CI, 0.17-0.85; P = .02) were associated with increased OS. CONCLUSIONS: Gemcitabine-based neoadjuvant chemotherapy confers a significant OS advantage by allowing the selection of patients who will derive greatest benefit from CRT. Median survival with this approach was similar to that seen with surgical resection.

Panitumumab in patients with KRAS wild-type colorectal cancer after progression on cetuximab.

PURPOSE: Cetuximab and panitumumab are monoclonal antibodies that target the epidermal growth factor receptor (EGFR) and are approved for the treatment of patients with KRAS wild-type meta-static colorectal cancer. There are no data that describe the activity of panitumumab in patients with progressive disease on cetuximab. We performed a single-arm phase II trial of panitumumab in patients with KRAS wild-type metastatic colorectal cancer that had progressed on prior cetuximab. PATIENTS AND METHODS: We used a two-stage study design to treat patients with panitumumab at 6 mg/kg every 14 days (cycle length = 28 days). Treatment was continued until disease progression, death, inability to tolerate panitumumab, or study withdrawal. The primary endpoint was response rate; secondary endpoints included progression-free survival and overall survival. Twenty patients were treated in the first stage, with plans to treat an additional twelve patients if there was at least one objective response. We collected blood samples at baseline and prior to cycles 2 and 3 to evaluate for the presence of anti-cetuximab and anti-panitumumab antibodies. RESULTS: We treated twenty patients for a median of two cycles (range 1-4). No patients responded, and 45% had a best response of stable disease (no progression for at least two cycles). Median progression-free survival was 1.7 months and median overall survival was 5.2 months. Panitumumab was well tolerated. Thirteen patients (65%) had grade 1-2 dry skin or rash, and three patients had treatment-related grade 3 toxicities (one each with hyperglycemia, hyperbilirubinemia, and hypokalemia). No patients had detectable anti-cetuximab antibodies at any time point; one patient developed anti-panitumumab antibodies. CONCLUSIONS: Panitumumab has minimal benefit in patients with KRAS wild-type metastatic colorectal cancer that has progressed on prior cetuximab. Discussion Both cetuximab and panitumumab competitively inhibit ligand binding to EGFR, thereby promoting receptor internalization and blocking receptor-mediated signaling. Although the two agents have never been compared directly in a randomized clinical trial, they produce similar response rates when used alone as well as in combination with cytotoxic agents. Cetuximab is a chimeric antibody with approximately 30% murine protein, while panitumumab is a fully human monoclonal antibody. Correspondingly, rates of severe hypersensitivity reactions are somewhat increased with cetuximab (3%) compared to panitumumab (1%). However, the potential efficacy of panitumumab in patients who have developed disease progression on cetuximab has been an open question. Metges et al. (PANERB trial) prospectively treated 32 KRAS wild-type metastatic colorectal cancer patients with cetuximab and irinotecan followed by panitumumab monotherapy after progression. Remarkably, the authors reported an objective response rate of 22% to panitumumab, including a disease control rate (objective response plus stable disease) of 73% in 11 patients who had previously responded to cetuximab and irinotecan. In contrast, we found no responders and a stable disease rate of 45% with a median duration of only 1.7 months in our trial of 20 patients. Moreover, no patients had detectable anti-cetuximab antibodies at baseline. It is not clear to what extent the PANERB trial included patients without objective disease progression on cetuximab or for whom cetuximab-containing regimens may have been ceased due to toxicity in the absence of disease progression. In both circumstances, retreatment with panitumumab may be expected to demonstrate some degree of clinical activity. In our study, disease progression after at least 4 weeks of cetuximab documented radiographically or by increased carcinoembryonic antigen (CEA) levels was required for inclusion in order to ensure that the study population demonstrated unequivocal evidence of progression on cetuximab. While it remains possible that a small subset of patients may benefit from panitumumab after progression on cetuximab, our results suggest that this approach should not be adopted until predictive biomarkers for panitumumab response in this setting have been discovered and validated. Until then, patients who develop progression on cetuximab should be enrolled in trials of novel agents.

Concurrent BRAFV600E and BRCA Mutations in MSS Metastatic Colorectal Cancer: Prevalence and Case Series of mCRC patients with prolonged OS.

BACKGROUND: BRAF V600E+ microsatellite stable (MSS) metastatic colorectal cancer (mCRC) patients comprise up to 10% of advanced CRC. They have a poor prognosis with a median survival typically <1 year. Despite use of multi-agent 1st line chemotherapy regimens and combination targeted therapies, outcomes are still poor. In our Institutional Molecular Tumor Board (MTB) database, we identified 3 mCRC patients with MSS/BRAF V600E who also had a BRCA1 or BRCA2 co-mutation and had relatively long overall survivals. Prior studies suggested that BRCA mutations are uncommon in CRC and we queried the Foundation Medicine (FM) genomic database to evaluate the prevalence of these cases as well as those with co-mutations in other homologous recombination genes. METHODS: 36,966 CRC pts were sequenced by FMI using hybrid capture comprehensive genomic profiling (CGP) to evaluate all classes of genomic alterations (GA) for pathogenic BRAF mutations and/or a mutation in BRCA1/2 or a co-mutation in other homologous recombination (HR) genes (BARD1, CDK12, FANCL, PALB2, ATM, RAD54L, CHEK2, BRAF, BRIP1, RAD51D, RAD51C, RAD51B, CHEK1). Selected cohort analysis of BRAF V600E co-mutated with BRCA1 and BRCA2 were separated into MSI-H and MSS cohorts. The clinicopathological features and genomic loss of heterozygosity (gLOH) of those with a BRAF V600E and a BRCA1/BRCA2 mutation were collected and analyzed. We also describe 3 consecutive cases of mCRC patients, identified through the Inova Schar Cancer Institute (ISCI) MTB registry, whom had prolonged OS. RESULTS: Of 36,966 colorectal cancer pts, 6.6% were BRAF V600E+ and 1.5% had any co-occurring HR gene mutation(s) with 0.6% of the total mCRC population having co-ocurring BRAF V600E and BRCA1/2 alterations. BRCA co-mutations were higher in MSI-High BRAF V600E, however 24.1% of co-occurrences were observed in MSS samples. BRCA1 co-mutation was more commonly associated with MSS BRAF V600E and was associated with a higher gLOH than MSI-H BRAF V600E (18.7% vs 2.8%; p <0.001). In our institutional MTB database, (3/241;1.2%) CRC patients were MSS, BRAF V600E+ with BRCA1 or BRCA2 co-mutations, all somatic in origin, with an average gLOH of 21.4% and overall survivals of 72+(alive), 17+(alive), and 30 months, respectively. CONCLUSION: Co-existence of BRAF V600E/BRCA1/2 may represent a unique subset of advanced MSS CRC that may have a better prognosis and represent an opportunity to test novel targeted therapies. The elevated gLOH in these cases may also be a valuable biomarker for these pts. Larger prospective clinical validation trials in this subset is warranted.

A phase 1/2 and biomarker study of preoperative short course chemoradiation with proton beam therapy and capecitabine followed by early surgery for resectable pancreatic ductal adenocarcinoma.

PURPOSE: To evaluate the safety, efficacy and biomarkers of short-course proton beam radiation and capecitabine, followed by pancreaticoduodenectomy in a phase 1/2 study in pancreatic ductal adenocarcinoma (PDAC) patients. METHODS AND MATERIALS: Patients with radiographically resectable, biopsy-proven PDAC were treated with neoadjuvant short-course (2-week) proton-based radiation with capecitabine, followed by surgery and adjuvant gemcitabine. The primary objective was to demonstrate a rate of toxicity grade ≥ 3 of <20%. Exploratory biomarker studies were performed using surgical specimen tissues and peripheral blood. RESULTS: The phase 2 dose was established at 5 daily doses of 5 GyE. Fifty patients were enrolled, of whom 35 patients were treated in the phase 2 portion. There were no grade 4 or 5 toxicities, and only 2 of 35 patients (4.1%) experienced a grade 3 toxicity event (chest wall pain grade 1, colitis grade 1). Of 48 patients eligible for analysis, 37 underwent pancreaticoduodenectomy. Thirty of 37 (81%) had positive nodes. Locoregional failure occurred in 6 of 37 resected patients (16.2%), and distant recurrence occurred in 35 of 48 patients (72.9%). With median follow-up of 38 months, the median progression-free survival for the entire group was 10 months, and overall survival was 17 months. Biomarker studies showed significant associations between worse survival outcomes and the KRAS point mutation change from glycine to aspartic acid at position 12, stromal CXCR7 expression, and circulating biomarkers CEA, CA19-9, and HGF (all, P<.05). CONCLUSIONS: This study met the primary endpoint by showing a rate of 4.1% grade 3 toxicity for neoadjuvant short-course proton-based chemoradiation. Treatment was associated with favorable local control. In exploratory analyses, KRAS(G12D) status and high CXCR7 expression and circulating CEA, CA19-9, and HGF levels were associated with poor survival.

Pancreatic neuroendocrine tumors with involved surgical margins: prognostic factors and the role of adjuvant radiotherapy.

PURPOSE: Pancreatic neuroendocrine tumors (pNET) are rare neoplasms associated with poor outcomes without resection, and involved surgical margins are associated with a worse prognosis. The role of adjuvant radiotherapy (RT) in these patients has not been characterized. METHODS AND MATERIALS: We retrospectively evaluated 46 consecutive patients with positive or close (<1 mm) margins after pNET resection, treated from 1983 to 2010, 16 of whom received adjuvant RT. Median RT dose was 50.4 Gy in 1.8-Gy fractions; half the patients received concurrent chemotherapy with 5-fluorouracil or capecitabine. No patients received adjuvant chemotherapy. Cox multivariate analysis (MVA) was used to analyze factors associated with overall survival (OS). RESULTS: Median age at diagnosis was 56 years, and 52% of patients were female. Median tumor size was 38 mm, 57% of patients were node-positive, and 11% had a resected solitary liver metastasis. Patients who received RT were more likely to have larger tumors (median, 54 mm vs. 30 mm, respectively, p = 0.002) and node positivity (81% vs. 33%, respectively, p = 0.002) than those not receiving RT. Median follow-up was 39 months. Actuarial 5-year OS was 62% (95% confidence interval [CI], 41%-77%). In the group that did not receive RT, 3 patients (10%) experienced local recurrence (LR) and 5 patients (18%) developed new distant metastases, while in the RT group, 1 patient (6%) experienced LR and 5 patients (38%) developed distant metastases. Of all recurrences, 29% were LR. On MVA, male gender (adjusted hazard ratio [AHR] = 3.81; 95% CI, 1.21-11.92; p = 0.02) and increasing tumor size (AHR = 1.02; 95% CI, 1.01-1.04; p = 0.007) were associated with decreased OS. CONCLUSIONS: Long-term survival is common among patients with involved-margin pNET. Despite significantly worse pathologic features among patients receiving adjuvant RT, rates of LR between groups were similar, suggesting that RT might aid local control, and merits further evaluation.

The role of targeted agents in preoperative chemoradiation for rectal cancer.

In the United States, randomized trials have established preoperative chemoradiation as the standard of care for patients with locally advanced rectal cancer. Pathologic complete response (pCR) rates occur in 10% to 16% of patients and have been shown to be correlated with both disease-free and overall survival. Therefore, recent efforts incorporating newer cytotoxic and molecularly targeted agents into chemoradiotherapy regimens have reported the pCR rate to be a surrogate marker of clinical outcomes. Substitution of oral fluoropyrimidines, including capecitabine, for infusional 5-fluorouracil reportedly generated pCR rates of up to 32% in phase 2 studies, but definitive evaluation awaits results from the National Surgical Adjuvant Breast and Bowel Project (NSABP) R-04 trial. Similarly, regimens incorporating irinotecan generated pCR rates as high as 38%, but to the authors' knowledge have not been evaluated in randomized trials. In contrast, 2 large randomized trials reported that the addition of weekly oxaliplatin to fluoropyrimidine-based chemoradiation led to an increase in grade 3/4 toxicity but no difference in pCR rates. Early phase trials evaluating the anti-epidermal growth factor receptor (EGFR) antibody cetuximab in combination with chemoradiation reported modest pCR rates of 5% to 12%, and efforts have focused on identifying biomarkers of response including EGFR copy number, k-ras mutational status, and both serum and tumor-specific expression of EGFR ligands. Finally, incorporation of the anti-vascular endothelial growth factor antibody bevacizumab into chemoradiation appears to be safe and feasible, with initial studies reporting a beneficial effect on vascular normalization and correlations between circulating biomarkers of angiogenesis and pathologic response. Future efforts should include prospective studies of these agents in biomarker-defined subpopulations, as well as studies of novel agents that target angiogenesis, tumor-stromal interaction, and the cell signaling pathways implicated in colorectal cancer.

Systems-level modeling of cancer-fibroblast interaction.

Cancer cells interact with surrounding stromal fibroblasts during tumorigenesis, but the complex molecular rules that govern these interactions remain poorly understood thus hindering the development of therapeutic strategies to target cancer stroma. We have taken a mathematical approach to begin defining these rules by performing the first large-scale quantitative analysis of fibroblast effects on cancer cell proliferation across more than four hundred heterotypic cell line pairings. Systems-level modeling of this complex dataset using singular value decomposition revealed that normal tissue fibroblasts variably express at least two functionally distinct activities, one which reflects transcriptional programs associated with activated mesenchymal cells, that act either coordinately or at cross-purposes to modulate cancer cell proliferation. These findings suggest that quantitative approaches may prove useful for identifying organizational principles that govern complex heterotypic cell-cell interactions in cancer and other contexts.

Umbilical cord blood transplantation: where do we stand?

Although allogeneic stem cell transplantation can cure patients with hematologic malignancies, limiting factors such as lack of suitable donors and GVHD toxicity have led to the exploration of umbilical cord blood (UCB) as an alternative source of hematopoietic stem cells. This overview examines the advantages and disadvantages of UCB as a donor source and reviews data from preclinical and clinical studies. Ethical issues regarding UCB transplantation are also addressed.