Impact of KRASG12 mutations on survival with trifluridine/tipiracil plus bevacizumab in patients with refractory metastatic colorectal cancer: post hoc analysis of the phase III SUNLIGHT trial

BACKGROUND

In metastatic colorectal cancer (mCRC), KRAS mutations are often associated with poorer survival; however, the prognostic impact of specific point mutations is unclear. In the phase III SUNLIGHT trial, trifluridine/tipiracil (FTD/TPI) plus bevacizumab significantly improved overall survival (OS) versus FTD/TPI alone. We assessed the impact of KRASG12 mutational status on OS in SUNLIGHT.

PATIENTS AND METHODS

In the global, open-label, randomized, phase III SUNLIGHT trial, adults with mCRC who had received no more than two prior chemotherapy regimens were randomized 1 : 1 to receive FTD/TPI alone or FTD/TPI plus bevacizumab. In this post hoc analysis, OS was assessed according to the presence or absence of a KRASG12 mutation in the overall population and in patients with RAS-mutated tumors.

RESULTS

Overall, 450 patients were analyzed, including 302 patients in the RAS mutation subgroup (214 with a KRASG12 mutation and 88 with a non-KRASG12RAS mutation). In the overall population, similar OS outcomes were observed in patients with and without a KRASG12 mutation [median 8.3 and 9.2 months, respectively; hazard ratio (HR) 1.09, 95% confidence interval (CI) 0.87-1.4]. Similar OS outcomes were also observed in the subgroup analysis of patients with a KRASG12 mutation versus those with a non-KRASG12RAS mutation (HR 1.03, 95% CI 0.76-1.4). FTD/TPI plus bevacizumab improved OS compared with FTD/TPI alone irrespective of KRASG12 mutational status. Among patients with a KRASG12 mutation, the median OS was 9.4 months with FTD/TPI plus bevacizumab versus 7.2 months with FTD/TPI alone (HR 0.67, 95% CI 0.48-0.93), and in patients without a KRASG12 mutation, the median OS was 11.3 versus 7.1 months, respectively (HR 0.59, 95% CI 0.43-0.81).

CONCLUSIONS

The presence of a KRASG12 mutation had no detrimental effect on OS among patients treated in SUNLIGHT. The benefit of FTD/TPI plus bevacizumab over FTD/TPI alone was confirmed independently of KRASG12 status.

Diet quality, liveweight change and responses to N supplements by cattle grazing

Experiments during 4 years examined the diets selected, growth, and responses to N supplements by Bos indicus-cross steers grazing summer-rainfall semi-arid C4 Astrebla spp. (Mitchell grass) rangelands at a site in north-western Queensland, Australia. Paddock groups of steers were not supplemented (T-NIL), or were fed a non-protein N (T-NPN) or a cottonseed meal (T-CSM) supplement. In Experiment 1, young and older steers were measured during the late dry season (LDS) and the rainy season (RS), while steers in Experiments 2–4 were measured through the annual cycle. Because of severe drought the measurements during Experiment 3 annual cycle were limited to T-NIL steers. Pasture availability and species composition were measured twice annually. Diet was measured at 1–2 week intervals using near infrared spectroscopy of faeces (F.NIRS). Annual rainfalls (1 July–30 June) were 42–68% of the long-term average (471 mm), and the seasonal break ranged from 17 December to 3 March. There was wide variation in pasture, diet (crude protein (CP), DM digestibility (DMD), the CP to metabolisable energy (CP/ME) ratio) and steer liveweight change (LWC) within and between annual cycles. High diet quality and steer liveweight (LW) gain during the RS declined progressively through the transition season (TS) and early dry season (EDS), and often the first part of the LDS. Steers commenced losing LW as the LDS progressed. In Experiments 1 and 2 where forbs comprised ≤15 g/kg of the pasture sward, steers selected strongly for forbs so that they comprised 117–236 g/kg of the diet. However, in Experiments 3 and 4 where forbs comprised substantial proportions of the pasture (173–397 g/kg), there were comparable proportions in the diet (300–396 g/kg). With appropriate stocking rates the annual steer LW gains were acceptable (121–220 kg) despite the low rainfall. The N supplements had no effect on steer LW during the TS and the EDS, but usually reduced steer LW loss by 20–30 kg during the LDS. Thus during low rainfall years in Mitchell grass pastures there were substantial LW responses by steers to N supplements towards the end of the dry season when the diet contained c. <58 g CP/kg or c. <7.0 g CP/MJ ME.

Effect of KRAS codon 12 or 13 mutations on survival with trifluridine/tipiracil in pretreated metastatic colorectal cancer: a meta-analysis

Background

KRAS gene mutations can predict prognosis and treatment response in patients with metastatic colorectal cancer (mCRC).

Methods

We undertook a meta-analysis of three randomized, placebo-controlled trials (RECOURSE, TERRA and J003) to investigate the impact of KRAS mutations in codons 12 or 13 on overall survival (OS) and progression-free survival in patients receiving trifluridine/tipiracil (FTD/TPI) for refractory mCRC.

Results

A total of 1375 patients were included, of whom 478 had a KRAS codon 12 mutation and 130 had a KRAS codon 13 mutation. In univariate analyses, the absence of a KRAS codon 12 mutation was found to significantly increase the OS benefit of FTD/TPI relative to placebo compared with the presence of the mutation {hazard ratio (HR), 0.62 [95% confidence interval (CI): 0.53-0.72] versus 0.86 (0.70-1.05), respectively; interaction P = 0.0206}. Multivariate analyses showed that taking confounding factors into account reduced the difference in treatment effect between the presence and the absence of KRAS codon 12 mutations, confirming that treatment benefit was maintained in patients with [HR, 0.73 (95% CI: 0.59-0.89)] and without [HR, 0.63 (95% CI: 0.54-0.74)] codon 12 mutations (interaction P = 0.2939). KRAS mutations in codon 13 did not reduce the OS benefit of FTD/TPI relative to placebo, and, furthermore, KRAS mutations at either codon 12 or codon 13 did not affect the progression-free survival benefit.

Conclusions

Treatment with FTD/TPI produced a survival benefit, relative to placebo, regardless of KRAS codon 12 or 13 mutation status in patients with previously treated mCRC.

●

KRAS mutations are associated with negative outcomes in patients with mCRC; codon 12 and 13 mutations are the most common.

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FTD/TPI was associated with longer median overall survival vs placebo both in patients with wild-type KRAS and mutant KRAS.

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FTD/TPI produced a survival benefit, relative to placebo, regardless of KRAS codon 12 or 13 mutation status in this patient group.

Neutropenia and survival outcomes in metastatic colorectal cancer patients treated with trifluridine/tipiracil in the RECOURSE and J003 trials

Background:

The phase II J003 (N = 169) and phase III RECOURSE (N = 800) trials demonstrated a significant improvement in survival with trifluridine (FTD)/tipiracil (TPI) versus placebo in patients with refractory metastatic colorectal cancer. This post hoc analysis investigated pharmacokinetic data of FTD/TPI exposure and pharmacodynamic markers, such as chemotherapy-induced neutropenia (CIN) and clinical outcomes.

Patients and methods:

A total of 210 patients from RECOURSE were enrolled in this substudy. A limited sampling approach was used, with three pharmacokinetic samples drawn on day 12 of cycle 1. Patients were categorized as being above or below the median area under the plasma concentration–time curve (AUC) for FTD and TPI. We conducted a post hoc analysis using the entire RECOURSE population to determine the correlations between CIN and clinical outcome. We then carried out a similar analysis on the J003 trial to validate the results.

Results:

In the RECOURSE subset, patients in the high FTD AUC group had a significantly increased CIN risk. Analyses of the entire population demonstrated that FTD/TPI-treated patients with CIN of any grade in cycles 1 and 2 had significantly longer median overall survival (OS) and progression-free survival (PFS) than patients who did not develop CIN and patients in the placebo group. Patients who required an FTD/TPI treatment delay had increased OS and PFS versus those in the placebo group and those who did not develop CIN. Similar results were obtained in the J003 cohort.

Conclusions:

In RECOURSE, patients with higher FTD drug exposure had an increased CIN risk. FTD/TPI-treated patients who developed CIN had improved OS and PFS versus those in the placebo group and those who did not develop CIN. Similar findings were reported in the J003 cohort, thus validating the RECOURSE results. The occurrence of CIN may be a useful predictor of treatment outcomes for FTD/TPI-treated patients.

ClinicalTrials.gov identifier:

NCT01607957 (RECOURSE).

Japan Pharmaceutical Information Center number:

JapicCTI-090880 (J003).

Estimating the voluntary intake by sheep of tropical grasses from digestibility, regrowth-age and leaf content: a meta-analysis

Context The voluntary intake (VI) of forages by ruminants is usually estimated from diet DM digestibility (DMD), but may be related also to the age of regrowth and the leaf blade content (Leaf) of the forage. Aim To examine the reliability of the prediction of the VI of tropical grasses by sheep from the DMD, Leaf and Regrowth-age characteristics of the forage. Methods Data from eight experiments with mature sheep fed tropical grass hay diets (n = 229) were used to explore prediction of VI of DM (VIDM), digestible DM (DDM) (VIDDM) and estimated metabolisable energy from the DMD, Leaf and Regrowth-age of the forage. Key results The variables were generally correlated. In data pooled across experiments the VI (g/kg W0.75.day) of DM was poorly correlated with DMD, Leaf or Regrowth-age (r = 0.30–0.52). The regressions between VI and each of the variables differed among experiments in elevation (P &lt; 0.001) but generally not in slope. When ‘experiment’ was included as a factor the VIDM (g/kg W0.75.day) = K + 0.0912 × DMD (R2 0.80; r.s.d. 6.8; K range –26.0 to +7.8; P &lt; 0.001). Also VIDM = K + 0.069 × DMD + 0.020 × Leaf (R2 0.88; r.s.d. 5.4; DMD and Leaf, P &lt; 0.001); thus inclusion of Leaf reduced the r.s.d. while K ranged widely (–20.5 to +12.0). The voluntary intake of digestible DM (VIDDM) = K + 0.081 × DMD + 0.011 × Leaf (R2 0.89; r.s.d. 3.2; DMD and Leaf P &lt; 0.001; K range –35.0 to –16.3). Regrowth-age was correlated with both Leaf and DMD, and VIDM was predicted by Regrowth-age or Leaf with comparable error. Because numerous factors alter the composition of grasses at a specific Regrowth-age the DMD should be a more generally suitable variable to predict intakes of forage DM and DDM. Conclusions The estimation of the VI of ruminants ingesting tropical grass forages can be improved if the diet Leaf is included with diet DMD as a predictor. However, the general prediction of VI of sheep may involve large errors. Implications Knowledge of the leaf content as well as the digestibility should improve estimation of VI of tropical grasses by ruminants.

Predicted vitamin D status and colon cancer recurrence and mortality in CALGB 89803 (Alliance)

Background

Observational studies suggest that higher levels of 25-hydroxyvitamin D3 (25(OH)D) are associated with a reduced risk of colorectal cancer and improved survival of colorectal cancer patients. However, the influence of vitamin D status on cancer recurrence and survival of patients with stage III colon cancer is unknown.

Patients and methods

We prospectively examined the influence of post-diagnosis predicted plasma 25(OH)D on outcome among 1016 patients with stage III colon cancer who were enrolled in a National Cancer Institute-sponsored adjuvant therapy trial (CALGB 89803). Predicted 25(OH)D scores were computed using validated regression models. We examined the influence of predicted 25(OH)D scores on cancer recurrence and mortality (disease-free survival; DFS) using Cox proportional hazards.

Results

Patients in the highest quintile of predicted 25(OH)D score had an adjusted hazard ratio (HR) for colon cancer recurrence or mortality (DFS) of 0.62 (95% confidence interval [CI], 0.44-0.86), compared with those in the lowest quintile (Ptrend = 0.005). Higher predicted 25(OH)D score was also associated with a significant improvement in recurrence-free survival and overall survival (Ptrend = 0.01 and 0.0004, respectively). The benefit associated with higher predicted 25(OH)D score appeared consistent across predictors of cancer outcome and strata of molecular tumor characteristics, including microsatellite instability and KRAS, BRAF, PIK3CA, and TP53 mutation status.

Conclusion

Higher predicted 25(OH)D levels after a diagnosis of stage III colon cancer may be associated with decreased recurrence and improved survival. Clinical trials assessing the benefit of vitamin D supplementation in the adjuvant setting are warranted.

ClinicalTrials.gov Identifier

NCT00003835.

Bone mineral density in the tail-bones of cattle: effect of dietary phosphorus status, liveweight, age and physiological status

In three grazing experiments in the seasonally dry tropics of Australia, growing steers (Experiment 1), first-calf cows (Experiment 2) and mature breeder cows (Experiment 3), ingested diets for 12–17 months, which were either adequate or severely deficient in phosphorus (P) (Padeq and Pdefic, respectively). Bone mineral density (BMD) at the proximal end of the ninth coccygeal vertebra (Cy9) was measured at intervals using single photon absorptiometry (SPA). Liveweight (LW) and plasma inorganic phosphorus (PIP) concentrations were monitored at intervals and rib-bone cortical bone thickness (CBT) of biopsy samples was measured at the end of Experiments 1 and 3. Measurements of LW change, PIP concentrations and CBT confirmed that diet P intakes of cattle in the Padeq treatments were adequate whereas there was severe and chronic P deficiency in the Pdefic treatments. In Experiment 1 BMD in Padeq steers increased with LW and age from ~0.25–0.27 g/cc (8 months, 200 kg LW) to ~0.34 g/cc (32 months, 490 kg LW), whereas in Pdefic steers BMD decreased progressively to ~0.23–0.24 g/cc. Although BMD decreased in the Pdefic steers bone volume of Cy9 (calculated from tail-bone thickness) increased, and some net bone deposition in the Cy9 continued. Rib-bone CBT and tail-bone BMD at the end of Experiment 1 were closely correlated (r = 0.93). In Experiment 2 BMD was initially 0.33 g/cc (~25 months, 400 kg LW) and did not change through pregnancy and lactation in Padeq cows. However, in the Pdefic cows there was a gradual decline in BMD to ~0.25 g/cc. There was no change in dimensions of the Cy9 so the decreases in BMD involved net demineralisation of bone. In Experiment 3 BMD was less responsive to P deficiency than in Experiments 1 and 2. Only after ~11 months was BMD reduced (P < 0.05) in the Pdefic cows, and then only by 15%. In contrast, rib-bone CBT decreased by 30% due to P deficiency, and BMD was poorly correlated with CBT (r = 0.4). The effects of animal weight, age and maturity on tailbone BMD of P-adequate animals, and the different responses to P deficiency observed in young growing steers, first-calf cows and mature breeders are discussed in relation to the use of SPA measured tail-bone BMD to diagnose P deficiency in grazing cattle.

Validation of single photon absorptiometry for on-farm measurement of density and mineral content of tail bone in cattle

A validation study examined the accuracy of a purpose-built single photon absorptiometry (SPA) instrument for making on-farm in vivo measurements of bone mineral density (BMD) in tail bones of cattle. In vivo measurements were made at the proximal end of the ninth coccygeal vertebra (Cy9) in steers of two age groups (each n = 10) in adequate or low phosphorus status. The tails of the steers were then resected and the BMD of the Cy9 bone was measured in the laboratory with SPA on the resected tails and then with established laboratory procedures on defleshed bone. Specific gravity and ash density were measured on the isolated Cy9 vertebrae and on 5-mm2 dorso-ventral cores of bone cut from each defleshed Cy9. Calculated BMD determined by SPA required a measure of tail bone thickness and this was estimated as a fraction of total tail thickness. Actual tail bone thickness was also measured on the isolated Cy9 vertebrae. The accuracy of measurement of BMD by SPA was evaluated by comparison with the ash density of the bone cores measured in the laboratory. In vivo SPA measurements of BMD were closely correlated with laboratory measurements of core ash density (r = 0.92). Ash density and specific gravity of cores, and all SPA measures of BMD, were affected by phosphorus status of the steers, but the effect of steer age was only significant (P < 0.05) for steers in adequate phosphorus status. The accuracy of SPA to determine BMD of tail bone may be improved by reducing error associated with in vivo estimation of tail bone thickness, and also by adjusting for displacement of soft tissue by bone mineral. In conclusion a purpose-built SPA instrument could be used to make on-farm sequential non-invasive in vivo measurements of the BMD of tailbone in cattle with accuracy acceptable for many animal studies.

Long-term update of U.S. GI Intergroup RTOG 98-11 phase III trial for anal carcinoma: Comparison of concurrent chemoradiation with 5FU-mitomycin versus 5FU-cisplatin for disease-free and overall survival

367

Background: On initial publication of GI Intergroup RTOG 98-11, concurrent chemoradiation with 5FU+mitomycin (MMC) decreased colostomy failure (CF) vs induction plus concurrent 5FU+cisplatin (CDDP), but did not significantly impact disease free or overall survival (DFS, OS). The intent of the current analysis is to determine the long-term impact of treatment on survival (DFS, OS, colostomy-free [CFS]), CF and relapse (local-regional [LRF], distant [DM]) in this patient group.

Methods: Stratification factors included gender, clinical node status, and primary size. DFS/OS were estimated univariately by Kaplan-Meier method and treatment arms compared by log-rank test. Time to relapse/CF were estimated by cumulative incidence method and treatment arms compared by Gray's test. Multivariate analyses were done with Cox proportional hazard models to test for treatment differences, adjusting for stratification factors.

Results: Of 682 patients accrued, 649 were analyzable for outcomes. As seen in the table, 5-yr DFS and OS were statistically better for RT+5FU/MMC vs RT+5FU/CDDP (67.7 v 57.6%, p=.0.0045; 78.2 v 70.5%, p=0.021) with trends toward statistical significance for CFS, LRF, and CF (71.8 v 64.9%, p=0.053; 20 v 26.5%, 11.9 v 17.3%, p=0.092 and 0.075). Similar results were seen in multivariate analysis.

Conclusions: Concurrent chemoradiation with 5FU-MMC has a statistically significant impact on DFS and OS vs induction + concurrent 5FU-CDDP and borderline significance for CFS, CF and LRF. Therefore, RT+5FU/MMC remains the preferred standard of care. Potential strategies to improve outcomes include treatment intensification and individualized molecular-based treatment. Supported by RTOG grant U10 CA21661 and CCOP grant U10 CA37422 from the National Cancer Institute (NCI).

[Table: see text]

No significant financial relationships to disclose.

Presence of 18q loss of heterozygosity (LOH) and disease-free and overall survival in stage II colon cancer: CALGB Protocol 9581

4012

Background: LOH at 18q is associated with poorer overall survival in patients with colon cancer; however available studies are retrospective and vary in analysis methods. We recently completed an 18qLOH assay method validation study, and after standardizing technique, this prospective study investigated the role of 18qLOH among patients with low-risk stage II colon cancer. Methods: In Cancer and Leukemia Group B (CALGB) protocol 9581, we randomized 1738 stage II patients to post-operative treatment with a 500 mg loading dose of monoclonal antibody 17–1A followed by four infusions of 100 mg every 28 days or observation. The primary endpoint was overall survival (OS); disease free survival (DFS) was a secondary endpoint. Status of 18qLOH was assessed in patients with available tissue and interpretable PCR results. Patients were excluded if their tumors were uninformative for 18qLOH or if their tumors displayed microsatellite instability. Results: We report 18qLOH data on 156 patients. Patient characteristics including treatment, age, gender, performance status, site and grade of tumor, were similar between all patients enrolled and the subset of patients with tumor samples analyzed. The DFS and OS for treated and observed patients were no different (5-yr DFS: 0.81 and 0.80, p= 0.96; 5-yr OS: 0.88 and 0.86, p=0.44 at a median of 6.8 yrs of follow-up) and the data were pooled across the study's arms. Of the tumors examined, 101 (65%) were positive for 18qLOH. A significantly lower proportion of patients with 18qLOH-positive tumors had proximal tumors (46.5% vs 65.5%; p=0.02). Significantly decreased DFS and OS were observed in patients with 18qLOH-positive tumors. Five-year DFS among patients with 18qLOH-positive tumors was 0.78 vs 0.93 among patients with 18qLOH-negative tumors [HR 0.39; 95% CI (0.16, 0.94); logrank p=0.03 based on 33 events]. Five-year OS among patients with 18qLOH-positive tumors was 0.85 vs 0.98 among patients with 18qLOH-negative tumors [HR 0.25; 95% CI (0.07, 0.83); logrank p=0.01 based on 24 events]. Conclusions LOH at 18q was prognostic for DFS and OS among patients with available tissue for analysis after resection of low-risk stage II colon cancer who were not treated with chemotherapy in the adjuvant setting.

[Table: see text]

KRAS mutation, cancer recurrence, and patient survival in stage III colon cancer: Findings from CALGB 89803

4037

Purpose: KRAS mutation in stage IV colorectal cancer predicts resistance to anti-EGFR targeted treatment (cetuximab or panitumumab). However, whether the presence of KRAS mutation independently predicts the survival of colon cancer patients remains uncertain. Methods: We conducted a prospective observational study of 508 cases identified among 1264 patients with stage III colon cancer who enrolled in a randomized adjuvant chemotherapy trial (5-fluorouracil, leucovorin with or without irinotecan) between April 1999 and May 2001 (CALGB 89803; Saltz et al. J Clin Oncol 2007). KRAS mutations were detected in 178 tumors (35%) by Pyrosequencing. Kaplan-Meier and Cox proportional hazard models were used to assess the significance of KRAS mutational status and adjusted for potential confounders including age, sex, tumor location, T stage, N stage, performance status, adjuvant chemotherapy arm and microsatellite instability (MSI) status. Results: When compared to patients with wild-type KRAS, those with a mutation in KRAS did not experience any difference in disease-free (DFS), recurrence-free (RFS), or overall survival (OS) (log-rank P>0.56 for DFS, RFS, and OS). Five-year DFS was 62% for KRAS-mutated and 63% for KRAS-wild-type patients. Five-year RFS was 64% for KRAS-mutated and 66% for KRAS- wild-type patients. Five-year OS was 74% for KRAS-mutated and 73% for KRAS-wild-type patients. The effect of KRAS mutation on patient survival did not differ according to clinical features, chemotherapy arm or MSI status, and the effect of adjuvant chemotherapy assignment on outcome did not differ according to KRAS status. Conclusions: In this large clinical trial of chemotherapy in patients with stage III colon cancer, KRAS mutational status was not associated with any significant influence on disease-free or overall survival.

No significant financial relationships to disclose.

Weekly docetaxel, cisplatin, and irinotecan (TPC): results of a multicenter phase II trial in patients with metastatic esophagogastric cancer

BACKGROUND

Recent studies have examined the addition of docetaxel to fluorouracil and cisplatin in advanced esophagogastric cancer.

PATIENTS AND METHODS

We carried out a phase I dose-escalation study of weekly docetaxel, cisplatin, and irinotecan (TPC), given on days 1 and 8 every 3 weeks, in patients with chemonaive solid tumors. Subsequently, we completed a multiinstitutional phase II study of TPC in patients with previously untreated, metastatic esophagogastric cancer.

RESULTS

Thirty-nine patients were enrolled in the phase I trial; a weekly schedule of TPC was well tolerated. On that basis, docetaxel 30 mg/m(2), cisplatin 25 mg/m(2), and irinotecan 65 mg/m(2) were selected for the phase II trial, where in the first 18 patients irinotecan 65 mg/m(2) caused too much diarrhea and was reduced to 50 mg/m(2). Among 56 eligible patients with previously untreated, metastatic esophagogastric cancer enrolled in the phase II trial, three complete and 27 partial responses were observed (overall response rate=54%), and 15 patients (30%) had stable disease. Median progression-free survival was 7.1 months, and median survival was 11.9 months. At the final irinotecan dose of 50 mg/m(2), grade 3 or higher toxicity included diarrhea (26%), neutropenia (21%), nausea (18%), fatigue (16%), anorexia (13%), and thrombosis/embolism (13%).

CONCLUSIONS

Weekly TPC is an active and well-tolerated regimen for patients with esophagogastric cancer.

Coordination of protein synthesis and degradation

The degree of coordination between protein synthesis and protein degradation in developing and mature cels is considered. Studies on specific enzyme and general protein turnover in developing liver and differentiating mammary gland are presented. In the mature liver mitochondrion average protein degradation rates are higher for outer membrane and intermembrane space proteins than for matrix and inner membrane proteins. Significant heterogeneity of protein degradation rates was observed only in the outer mitochondrial membrane. During postnatal development the rates of degradation of proteins in many liver cellular fractions are increased. In the mitochondrion only the average rates of degradation of proteins in the outer membrane and intermembrane space fractions increase during development. Evidence for hormonally regulated changes in both protein synthesis and degradation during mammary cell differentiation is given. The data indicate that a transitory decrease in protein degradation accompanies the increase in protein synthesis on hormonal stimulation of the tissue. The results from the two model systems are collated and used to formulate a phenomenological hypothesis of protein degradation and its integration with protein synthesis in steady-state and non-steady-state conditions.

Ratio of metastatic to examined lymph nodes is a powerful predictor of overall survival in rectal cancer: An analysis of Intergroup 0114

4006

Background: Lymph node (LN) metastasis is associated with decreased survival in rectal cancer. It has been suggested that at least 14 LN be evaluated for adequate staging. However, a large percentage of patients have fewer than the recommended number of LN examined. We hypothesized that LN ratio would be predictive of overall survival in rectal cancer. Methods: Data was analyzed from Intergroup 0114, a mature trial of postoperative adjuvant chemotherapy and radiation in T3/4 and/or LN positive rectal cancer. Survival was the same for all arms allowing the entire group to be considered as one. The primary endpoint evaluated was overall survival. A proportional hazards model was used to determine the relative prognostic impact of LN ratio compared to number of LN examined, number of positive LN, number of negative LN and AJCC nodal stage. LN ratio was defined as the number of positive LN divided by the total number of LN examined. Four groups were analyzed based on proportion of positive LN: =0.25, >0.25–0.50, >0.50–0.75 and >0.75. Results: 1,648 patients were evaluable. There were 251 T1/2, 1,251 T3 and 146 T4 tumors. 513 patients were N0, 743 N1 and 392 N2. Median number of LN was 9. LN ratio was predictive of 5-year overall survival with rates of 0.71, 0.56, 0.50 and 0.43 respectively when analyzed by quartile (p<0.0001). LN ratio remained significant when overall survival was analyzed by number of LN examined and grouped into <10, <15 and >15 nodes evaluated (p<0.0001 for all). LN ratio also predicted overall survival in N1 (p=0.04) and N2 (p=0.0002) disease. When comparing LN ratio (χ2=79.5, p<0.0001) to number of LN examined (χ2=4.7, p=0.03), number of positive LN (χ2=38, p<0.0001), number of negative LN (χ2=32, p<0.0001) and AJCC nodal stage (χ2=55.5, p<0.0001), LN ratio appears to be the strongest predictor of overall survival. Conclusion: LN ratio predicts overall survival in patients with resected rectal cancer. Importantly, this is true in patients who have had a small number of LN evaluated, in addition to those with a large number of LN examined. LN ratio also appears to be a stronger predictor of overall survival than other described LN prognostic factors. LN ratio may be a useful variable to stratify outcome in patients with node-positive rectal cancer.

No significant financial relationships to disclose.

The impact of dietary patterns on cancer recurrence and survival in patients with stage III colon cancer: Findings from CALGB 89803

4019

Background: Dietary factors have been associated with the risk of developing colon cancer; the influence of diet on pts with established disease is unknown. Methods: We conducted a prospective observational study of 1,009 patients with stage III colon cancer enrolled in a phase III adjuvant chemotherapy trial. Patients reported on dietary intake using a food frequency questionnaire during and 6 months after adjuvant chemotherapy. We identified two major dietary patterns, prudent and Western, by factor analysis. The prudent pattern was characterized by higher intake of fruits, vegetables, poultry and fish; the Western pattern by higher intake of red meat, fat, refined grains and desserts. Since there was no difference in efficacy between the 2 treatments, data for all pts were combined and analyzed according to quintiles of each dietary pattern. Patients were followed for cancer recurrence or death. Results: A higher intake of a Western pattern diet after cancer diagnosis was associated with a significantly worsened disease-free survival (DFS). After adjustment for gender, age, T and N stage, body mass index, physical activity level, weight change, baseline performance status, and treatment arm, patients in the highest quintile of Western pattern diet intake experienced a hazard ratio for DFS of 3.15 (95% confidence interval [CI], 1.76–5.63; p trend = <0.0001), compared to those in the lowest quintile. Western pattern diet was associated with a similar detriment in recurrence-free survival (adjusted p trend = 0.001) and overall survival (adjusted p trend = 0.0002). In contrast, prudent pattern diet did not significantly influence cancer recurrence or mortality. Conclusions: Higher intake of a Western pattern diet may increase the risk of recurrence and mortality among patients with stage III colon cancer patients treated with surgery and adjuvant chemotherapy. Further studies are needed to delineate which components of such a diet are most influential.

[Table: see text]

No significant financial relationships to disclose.

Phase II study of FOLFOX, bevacizumab and erlotinib as first-line therapy for patients with metastatic colorectal cancer

BACKGROUND

Targeting the epidermal growth factor receptor and angiogenesis have proven useful strategies against metastatic colorectal cancer. The benefit of combining inhibitors of both pathways is unknown.

PATIENTS AND METHODS

Patients with previously untreated metastatic colorectal cancer were enrolled in a phase II trial of infusional 5-fluorouracil, leucovorin, oxaliplatin (FOLFOX), bevacizumab and erlotinib. The primary end point was progression-free survival.

RESULTS

Thirty-five patients were enrolled and all came off trial for reasons other than progression; 18 (51%) had protocol-defined adverse events requiring removal, nine (26%) withdrew consent due to toxicity, six pursued surgery or localized therapies and two requested a treatment holiday. Principal toxic effects included rash, neuropathy and diarrhea. Seven patients came off trial before first restaging. By intention-to-treat analysis, one patient had a confirmed complete response, 10 had confirmed partial responses and one had an unconfirmed partial response (response rate = 34%). One patient had progressive disease at time of withdrawal from the trial, thus progression-free survival could not be calculated.

CONCLUSION

The combination of FOLFOX, bevacizumab and erlotinib led to higher than expected early withdrawal due to toxicity, limiting conclusions regarding efficacy. These findings raise concern regarding the tolerability of adding more agents to already complex combination regimens for metastatic colorectal cancer.

Gankyrin, the 26 S proteasome, the cell cycle and cancer

The known molecular players in cell-cycle control are much studied, not only to learn more about this intricate system, but also to understand the molecular features of oncogenic transformation. Infrequently, new players are discovered that change the interpretation of cell-cycle control. Gankyrin is one such player and was discovered in yeast two-hybrid screens as a new proteasomal subunit that interacts specifically with the S6b (rpt3) AAA (ATPase associated with various cellular activities) ATPase, which, with five other AAAs, are present in the so-called base of the 19 S regulator of the 26 S proteasome. Gankyrin is also the first liver oncogene. Gankyrin is found in other complexes that contain Rb (retinoblastoma protein) and the ubiquitin protein ligase Mdm2 (murine double minute 2). Gankyrin increases the hyperphosphorylation of Rb and therefore activates E2F-dependent transcription of DNA synthesis genes. Additionally, gankyrin, by binding to Mdm2, increases the ubiquitylation and degradation of p53 and prevents apoptosis. Gankyrin controls the functions of two major tumour suppressors and, when overexpressed, causes hepatocellular carcinoma.

Microsatellite instability predicts improved response to adjuvant therapy with irinotecan, 5-fluorouracil and leucovorin in stage III colon cancer

10003

Background: Colon cancers exhibiting a high level of microsatellite instability (MSI-H) show distinct clinicopathological features, including both better prognosis and reduced response to 5-fluorouracil (5-FU)-based chemotherapy. We investigated the impact of adjuvant chemotherapy containing irinotecan in patients with MSI-H colon cancers. Methods: CALGB protocol 89803 randomized 1264 patients with resected stage III colon cancer to receive post-operative 5-FU and leucovorin (LV) with or without irinotecan. Paraffin blocks containing primary tumor and normal tissue were collected. Microsatellite instablility was assessed using a panel of mono- and di-nucleotide markers. Disease free survival (DFS) was measured from trial entry until documented disease progression or death from any cause. A statistical significance level of 0.2 was used in screening to generate hypotheses regarding MSI status and outcome. Median follow-up at analysis was 3.8 years. Overall C89803 showed no advantage for addition of irinotecan to 5-FU/LV. Results: Patients with and without tumor samples analyzed did not differ by treatment, age, gender, primary site, T-stage, differentiation, # positive nodes, or mucinous type. Of 482 tumors analyzed, 75 (16%) demonstrated MSI-H. MSI-H cancers were more likely to be located in the proximal colon (p<0.0001), of high histologic grade (p<0.0001) and mucinous histology (p<0.0001), and also had increased numbers of tumor-containing lymph nodes (mean # positive nodes/case = 3.5 for MSI Low/Stable vs. 4.7 for MSI-H; p = 0.04). At the time of analysis 143 of 482 patients (36%) analyzed experienced tumor recurrence and/or death due to any cause. For patients with MSI-H tumors, DFS was better in those treated with irinotecan in addition to 5-FU/LV (logrank p=0.18). Among patients with MSI Low/Stable tumors there was no difference in DFS between those treated with and without irinotecan (logrank p =0.39). Conclusions: Early results from CALGB protocol 89803 indicate that addition of postoperative irinotecan to 5-FU/LV may improve DFS in patients with stage III colon cancers that exhibit MSI-H. Longer follow-up is required to confirm this finding.

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ECOG E3201: Intergroup randomized phase III study of postoperative irinotecan, 5- fluorouracil (FU), leucovorin (LV) (FOLFIRI) vs oxaliplatin, FU/LV (FOLFOX) vs FU/LV for patients (pts) with stage II/ III rectal cancer receiving either pre or postoperative radiation (RT)/ FU

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Background: In the US pts with stage II/III rectal cancer routinely receive pre or postoperative RT/FU. To date, in addition to chemoradiation, standard adjuvant chemotherapy has been limited to single agent FU. Improved survival with irinotecan and oxaliplatin in pts with metastatic colorectal cancer led to exploration of combination chemotherapy in the adjuvant setting in pts with rectal cancer. Methods: Pts on E3201 (T3–4 Nany M0, T1- 2 N + M0) had the option to receive FU with either pre- or postoperative RT (50.4 Gy). Pts were randomized to postoperative chemotherapy: FU (500mg/m2) + LV (500mg/m2) weekly x 6/8 wks x 3 cycles or irinotecan (FOLFIRI) (180mg/m2) vs oxaliplatin (FOLFOX) (85mg/m2) both administered with LV (400 mg/m2) FU (400mg/m2 bolus) + continuous FU (2.4 gm/m2/46 hours) q 2 wks x 8 cycles. Results: 225 pts of 3150 planned were recruited. 178 pts were randomized and 126 pts submitted treatment completion forms (accrual period 10/03–4/05). The Data Monitoring Committee closed E3201 when the GI Intergroup developed an alternative trial with bevacizumab (E5204). Toxicity information is reported for 93% of pts (165/178) ( Table ). There were no significant differences in toxicity between those pts treated with pre- vs postoperative RT/FU, although, for the subset of pts who received adjuvant FOLFIRI after postoperative RT/FU, there was a trend towards more diarrhea. Conclusion: FOLFOX as rectal adjuvant therapy is a common platform for new clinical trials, although there have been limited toxicity data reported. E3201 provides important comparative toxicity information demonstrating that FOLFOX can be safely administered to rectal cancer pts following chemoradiation.

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Intergroup RTOG 98–11: A phase III randomized study of 5-fluorouracil (5-FU), mitomycin, and radiotherapy versus 5-fluorouracil, cisplatin and radiotherapy in carcinoma of the anal canal

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Background: An ∼65% 5-year disease-free-survival (DFS) rate from 5-FU/mitomycin/radiation for anal carcinoma needs improvement. Methods: A phase III randomized trial compared 5-FU (1,000mg/m2 days 1–4 and 29–32) plus mitomycin (10mg/m2 days 1 and 29) and radiation (45 to 59 Gy) (Arm A) to 5-FU (1,000mg/m2 days 1–4, 29–32, 57–60 and 85–88) plus cisplatin (75mg/m2 on days 1, 29, 57 and 85) and radiation (45 to 59 Gy; start day=57) (Arm B) in anal carcinoma patients. Stratification included gender, clinical N status and tumor diameter. Primary endpoint was DFS. Statistical power was 80% with two-sided test to detect 10% DFS increase for Arm B. Results: Of 682 patients accrued, 598 were analyzable. Most unanalyzed patients’ data are early. Patient characteristics were balanced. Median age was 55 years, women predominated (69%), 27.5% had >5 cm tumor diameter and 26% had clinically N+ cancer. Preliminary 5-year estimated DFS was 56% for Arm A and 48% for Arm B (p=0.28) and 5-year estimated overall survival was 69% for both arms (p=0.24). Men(p=0.04), clinically N+ cancer (p<0.0001) and tumor diameter >5 cm (p=0.005) independently prognosticated DFS in a multivariate analysis. 5-year colostomy rate was 10% for Arm A and 20% for arm B(p=0.12). Grade 3/4 toxicity rates: non-hematologic=76% for Arm A and 75% for Arm B but hematologic=67% for Arm A and 47% for Arm B(p=0.0004). Conclusions: In Intergroup-98–11, induction 5-FU/cisplatin followed by 5-FU/cisplatin/radiation failed to improve DFS compared to the standard treatment, 5-FU/mitomycin/radiation. Supported by RTOG U10 CA21661, CCOP U10 CA37422, Stat U10 CA32115.

No significant financial relationships to disclose.

Analysis of surgical salvage after failure of primary therapy in rectal cancer: results from Intergroup Study 0114

PURPOSE

Intergroup Study 0114 was designed to study the effect of various chemotherapy regimens delivered after potentially curative surgical resection of T3, T4, and/or node-positive rectal cancer. A subset analysis was undertaken to investigate the prevalence and influence of salvage therapy among patients with recurrent disease.

PATIENTS AND METHODS

Adjuvant therapy consisted of two cycles of fluorouracil (FU)-based chemotherapy followed by pelvic irradiation with chemotherapy and two more cycles of chemotherapy after radiation therapy. A total of 1,792 patients were entered onto the study and 1,696 were assessable. After a median of 8.9 years of follow-up, 715 patients (42%) had disease recurrence, and an additional 10% died without evidence of disease. Five hundred patients with follow-up information available had a single organ or single site of first recurrence (73.5% of all recurrences).

RESULTS

A total of 171 patients (34% of those with a single organ or single site of recurrence) had a potentially curative resection of the metastatic or locally recurrent disease. Single-site first recurrences in the liver, lung, or pelvis occurred in 448 patients (90% of the single-site recurrences), with 159 (35%) of these undergoing surgical resection for attempted cure. Overall survival differed significantly between the resected and nonresected groups (P <.0001), with overall 5-year probabilities of.27 and.06, respectively. Controlling for worst performance status at the time of recurrence does not alter this relationship. Patients who underwent salvage surgery had significantly increased survival (P <.001) for each site.

CONCLUSION

Attempted surgical salvage of rectal cancer recurrence is performed commonly in the United States. The chance of a long-term cure with such intervention is approximately 27%.

Colon cancer survival is associated with increasing number of lymph nodes analyzed: a secondary survey of intergroup trial INT-0089

PURPOSE

To determine the relationship, in patients with adenocarcinoma of the colon, between survival and the number of lymph nodes analyzed from surgical specimens.

PATIENTS AND METHODS

Intergroup Trial INT-0089 is a mature trial of adjuvant chemotherapy for high-risk patients with stage II and stage III colon cancer. We performed a secondary analysis of this group with overall survival (OS) as the main end point. Cause-specific survival (CSS) and disease-free survival were secondary end points. Rates for these outcome measures were estimated using Kaplan-Meier methodology. Log-rank test was used to compare overall curves, and Cox proportional hazards regression was used to multivariately assess predictors of outcome.

RESULTS

The median number of lymph nodes removed at colectomy was 11 (range, one to 87). Of the 3411 assessable patients, 648 had no evidence of lymph node metastasis. Multivariate analyses were performed on the node-positive and node-negative groups separately to ascertain the effect of lymph node removal. Survival decreased with increasing number of lymph node involvement (P =.0001 for all three survival end points). After controlling for the number of nodes involved, survival increased as more nodes were analyzed (P =.0001 for all three end points). Even when no nodes were involved, OS and CSS improved as more lymph nodes were analyzed (P =.0005 and P =.007, respectively).

CONCLUSION

The number of lymph nodes analyzed for staging colon cancers is, itself, a prognostic variable on outcome. The impact of this variable is such that it may be an important variable to include in evaluating future trials.

Proteasomal interactors control activities as diverse as the cell cycle and glutaminergic neurotransmission

The six regulatory non-redundant ATPases in the base of the 19 S regulator of the 26 S proteasome belong to the AAA superfamily of ATPases. Yeast two-hybrid genetic screens, biochemical analyses and cell biological studies have identified and characterized new interactors of the human S6 (rpt3) and S8 (rpt6) ATPases of the 19 S regulator of the 26 S proteasome. The S6 ATPase interacts with gankyrin. This protein is found in purified human 26 S proteasomes and in a smaller complex(es) containing CDK4 and free S6 ATPase. Gankyrin overexpression causes the phosphorylation of the retinoblastoma protein (pRb) and the release of E2F transcription factor to trigger the expression of DNA synthesis genes. Gankyrin is oncogenic in nude mice and is overexpressed in hepatocellular carcinoma cells (HCCs). The S8 ATPase interacts with members of the large Homer-3 protein family. There are three Homer genes; the Homer 1 and 2 gene products control trafficking and calcium-store-related functions of metabotropic glutamate receptors (e.g. mGluR1alpha). Homer-3A11 by binding to the S8 ATPase brings mGluR1alpha to the 26 S proteasome for degradation. The degradation of mGluR1alpha is blocked by proteasomal inhibitors and by overexpression of the N-terminus of Homer which binds to the receptor. The S8 ATPase and mGluR1alpha are co-localized in Purkinje dendrites in rat cerebellum. The data are discussed in terms of the regulation of the cell cycle and glutaminergic receptor functions by the 26 S proteasome.

Adjuvant therapy in rectal cancer: analysis of stage, sex, and local control--final report of intergroup 0114

PURPOSE

The gastrointestinal Intergroup studied postoperative adjuvant chemotherapy and radiation therapy in patients with T3/4 and N+ rectal cancer after potentially curative surgery to try to improve chemotherapy and to determine the risk of systemic and local failure.

PATIENTS AND METHODS

All patients had a potentially curative surgical resection and were treated with two cycles of chemotherapy followed by chemoradiation therapy and two additional cycles of chemotherapy. Chemotherapy regimens were bolus fluorouracil (5-FU), 5-FU and leucovorin, 5-FU and levamisole, and 5-FU, leucovorin, and levamisole. Pelvic irradiation was given to a dose of 45 Gy to the whole pelvis and a boost to 50.4 to 54 Gy.

RESULTS

One thousand six hundred ninety-five patients were entered and fully assessable, with a median follow-up of 7.4 years. There was no difference in overall survival (OS) or disease-free survival (DFS) by drug regimen. DFS and OS decreased between years 5 and 7 (from 54% to 50% and 64% to 56%, respectively), although recurrence-free rates had only a small decrease. The local recurrence rate was 14% (9% in low-risk [T1 to N2+] and 18% in high-risk patients [T3N+, T4N]). Overall, 7-year survival rates were 70% and 45% for the low-risk and high-risk groups, respectively. Males had a poorer overall survival rate than females.

CONCLUSION

There is no advantage to leucovorin- or levamisole-containing regimens over bolus 5-FU alone in the adjuvant treatment of rectal cancer when combined with irradiation. Local and distant recurrence rates are still high, especially in T3N+ and T4 patients, even with full adjuvant chemoradiation therapy.

Efficacy of neo- and adjuvant treatment modalities in gastrointestinal cancer patients

Data which have emerged from randomized clinical trials are inconclusive regarding the efficacy of neoadjuvant chemoradiation therapy for patients with esophageal cancer. In 2001, available data appear to support the use of adjuvant chemoradiation therapy following the complete resection of a gastric cancer, adjuvant chemotherapy following the resection of a stage III (and--probably--"high-risk" stage II) colon cancer, and the use of adjuvant (and most likely neoadjuvant) chemoradiation therapy for stages II and III rectal cancer.

CD23 shedding: requirements for substrate recognition and inhibition by dipeptide hydroxamic acids

CD23 (low affinity IgE receptor, FcepsilonRII) is expressed as a Type II extracellular protein on a variety of cells such as B cells, monocytes and macrophages and is cleaved from the cell surface to generate several distinct fragments. The expression of CD23 on the cell surface as well as the generation of soluble fragments of CD23 has been shown to be involved in regulation of IgE synthesis. CD23 is released from the cell surface by a metalloprotease, analogous to the cleavage of other cell surface molecules such as TNF-alpha. This activity has been extensively studied with respect to biochemical characterization and ability to cleave specific mutants of CD23. Both local sequence and distal domains have been shown to affect cleavage of CD23. Selective dipeptide hydroxamic acid inhibitors of CD23 processing have been identified and demonstrated to very potently and selectively inhibit CD23 processing.

Prominent stress response of Purkinje cells in Creutzfeldt-Jakob disease

To examine the role of stress-related 70-kDa heat shock proteins (Hsp-s) in Creutzfeldt-Jakob disease (CJD), we performed immunocytochemistry to detect Hsp-72 and Hsp-73, together with the abnormal (PrP(Sc)) and the presumed cellular form (PrP(C)) of the prion protein, and TUNEL method to measure cellular vulnerability in different brain regions in CJD and control cases. While Hsp-73 showed uniform distribution in all the examined samples, an increase in the number of Purkinje cells with prominent accumulation of Hsp-72 in the CJD group was observed. These neurons also showed intense PrP(C) staining, but TUNEL-positive nuclei were only detected in the granular (Hsp-72-negative) cell layer. Fewer cells of the inferior olivary nucleus were immunoreactive for Hsp-72 in CJD than in control cases, and regions showing severe spongiform change and gliosis exhibited fewer Hsp-72-immunoreactive neurons. Our results indicate that accumulation of the inducible Hsp-72 in certain cell types may be part of a cytoprotective mechanism, which includes preservation of proteins like PrP(C).

Expression and purification of stable 33-kDa soluble human CD23 using the Drosophila S2 expression system

CD23, a 45-kDa type II membrane glycoprotein present on B cells, monocytes, and other human immune cells, is a low-affinity receptor for IgE. The extracellular region of the membrane-bound human CD23 is processed into at least four soluble (s) CD23 forms, with apparent molecular masses of 37, 33, 29, and 25 kDa. High levels of sCD23 are found in patients with allergy, certain autoimmune diseases, or chronic lymphocytic leukemia. Therefore, inhibition of the processing of membrane-bound CD23 to control the cytokine-like effects of sCD23 offers a novel therapeutic opportunity. While the 37-, 29-, and 25-kDa forms of sCD23 have been expressed previously as recombinant proteins, the 33-kDa form has not been purified and characterized. To further investigate the multiple roles of sCD23 fragments and to devise assays to identify potent small-molecule inhibitors of CD23 processing, we have produced the 33-kDa form of sCD23 using Chinese hamster ovary (CHO) and Drosophila S2 cells. The CHO-expressed 33-kDa protein was found to undergo proteolytic degradation during cell growth and during storage of purified protein, resulting in accumulation of a 25-kDa form. The Drosophila system expressed the 33-kDa sCD23 in a stable form that was purified and demonstrated to be more active than the CHO-derived 25-kDa form in a monocyte TNFalpha release assay.