Exploring feature-based approaches in PET images for predicting cancer treatment outcomes

Accumulating evidence suggests that characteristics of pre-treatment FDG-PET could be used as prognostic factors to predict outcomes in different cancer sites. Current risk analyses are limited to visual assessment or direct uptake value measurements. We are investigating intensity-volume histogram metrics and shape and texture features extracted from PET images to predict patient's response to treatment. These approaches were demonstrated using datasets from cervix and head and neck cancers, where AUC of 0.76 and 1.0 were achieved, respectively. The preliminary results suggest that the proposed approaches could potentially provide better tools and discriminant power for utilizing functional imaging in clinical prognosis.

Development and validation of a digital head posture measuring system

PURPOSE

To report the accuracy and repeatability of a new digital head posture measuring system.

DESIGN

Prospective study, clinical laboratory investigation.

METHODS

The digital head posture measuring system consists of a head-mounted motion tracker, a standard personal computer, and customized software to sample and display 3-dimensional (3D) head posture in real-time. Using a mechanical head posture measuring device as a reference, 3D head positions of an artificial head and 12 human subjects were recorded with the digital head posture device. Accuracy of the digital device outputs, relationship between digital outputs and actual head rotations, and repeatability of the tests were analyzed.

RESULTS

The digital head posture device showed consistent outcomes when compared to the mechanical one. The digital outputs of 3D rotations are very close to actual artificial head and human head rotations. The correlation coefficients of the linear relationship between the digital outputs and actual head movements were greater than 0.99. Repeatability tests for the artificial head and human subjects for all 3D rotations had 95% limits of agreement angles less than +/-6 degrees and +/-8 degrees, respectively.

CONCLUSIONS

The digital head posture device is an acceptable device with high accuracy, repeatability, and validity in measuring head posture in 3 dimensions.

Association of gender, age, and ethnicity with survival in patients with pancreas cancer

e15587

Background: Pancreatic cancer (PC) is the fourth leading cause of cancer death in the United States. However little is still known about factors that influence its development and progression. Recent data suggest that PC is, at least in part, an estrogen- dependent disease; there is growing epidemiological evidence that aspects of reproductive history and hormonal exposure are associated with risk of this disease. It was shown that age at menarche of <13 is associated with less risk of PC. However no data are available whether gender is associated with outcome in patients with PC. The purpose of this study was to test whether age, gender or ethnicity influence the outcome in PC. Methods: The data of the 50,302 adults diagnosed with PC between 1988 and 2004 were extracted from the Surveillance Epidemiology and End Results public use database. These included 24,240 patients diagnosed with localized pancreatic cancer (LPC) and 26,062 patients with metastatic pancreatic cancer (MPC). Demographic, clinical variables and survival time were retrieved. The primary endpoint was overall survival. We constructed Cox proportional hazards models to evaluate association between patient characteristics and survival in LPC and MPC separately. Pair interactions were also tested. Results: On multivariate analysis gender, age, race, marital status, tumor size, grade, histology, type of treatment and lymph node involvement were found to be independent predictors of survival. Females had a significant longer survival, with an HR of 0.959 (95% CI: 0.932–0.987) among patients with LPC and an HR of 0.918 (95%CI: 0.894–0.942) among patients with MPC. Each age group displayed a significant longer survival than its correspondent older age group. When we combined age and gender in the analysis, females had a longer survival than males in each single age group in the MPC group. In the LPC group the longer survival of female patients was only observed in the youngest age group. Conclusions: This is the first and largest study to address gender and outcome in PC. Our data suggest that the estrogen pathway may play an important prognostic role in patient with this disease. These data also warrant further in vitro and in vivo investigations on the mechanisms of estrogen and pancreas progression.

No significant financial relationships to disclose.

Colorectal cancer susceptibility variants and clinical outcome in adjuvant and metastatic colorectal cancer

4051

Background: Recent genome-wide association studies had identified colorectal cancer susceptibility loci on chromosomes 8q24 (rs6983267), 15q13(rs4779584), 18q21(rs4939827, rs12953717 and rs4464148), 10p14(rs10795668) and 8q23.3(rs16892766). Although the function role of these germline variants are unclear, given the importance of these variants and colorectal cancer risk, we have carried out the first pilot study to explore the association of these variants and clinical outcome. We used pooled data from two CRC-cohorts (locally advanced and metastatic CRC), and investigated the hypothesis that these germline variants may be associated with clinical outcome in adjuvant and metastatic colorectal cancer patients. Methods: Whole blood was collected from 515 patients with locally advanced (n=197) and metastatic CRC (n=318). After extraction of genomic-DNA, germline variants were genotyped as previously described (Haiman et al, Nat Genet, 2007). The genotype success rate was 98%. Blinded repeat samples (5%) were included for quality control purposes; genotype concordance was ≥ 99%. Results: Our results suggest that rs10795668 at 10p14 and rs719725 are significantly associated with time to tumor recurrence in adjuvant colorectal cancer patients, patients with rs10795668 AA genotype had significantly increased risk of time to tumor recurrence compared with those harboring G allele (TG+GG) patients(p=0.05, log-rank test). In metastatic cancer patients, we found rs4939827 at 18q21.1 were significantly associated with overall survival in female patients and rs10795668 at 10p14 were significantly associated with OS in male patients, respectively (p<0.05). Conclusions: Our preliminary results suggest cancer risk alleles may also associated with clinical outcome in adjuvant and metastatic colorectal cancer. Moreover, this correlation is sex-specific in metastatic colorectal cancer. Further comprehensive trials warranted to confirm our pilot findings.

[Table: see text]

Wt Kras and gene expression levels of VEGFR2, EGFR, and ERCC-1 associated with progression-free survival (PFS) in patients (pts) with metastatic colorectal cancer (mCRC) treated with first-line 5-FU or capecitabine with oxaliplatin and bevacizumab (FOLFOX/BV or XELOX/BV)

4056

Background: While wild type (wt) Kras is associated with improved outcome to anti-EGFR therapy in pts with mCRC, there are no identified predictors of outcome for FOLFOX/BV. We evaluated Kras status and expression of genes involved in angiogenesis, DNA repair and 5-FU metabolism in 68 patients treated with FOLFOX/BV or XELOX/BV. These genes included VEGF, VEGF-receptor 2 (KDR), Cox-2, IL 6 and 8, chemokine-receptors 1 & 2, EGFR and ERCC-1. Methods: Tissue samples from 68 patients with mCRC were analyzed. mRNA was extracted from laser-capture-microdissected tumor tissue. cDNA was prepared by reverse transcription and quantitation of the candidate genes was performed using a fluorescence- based real-time detection method (TaqMan). Allele specific RT-PCR was performed to determine Kras mutation status in codons 12 and 13. Results: There were 68 pts (38 males, 30 females), median age: 56 years (range 29–81). All received first line 5FU, oxaliplatin and BV (28 FOLFOX/BV, 40 XELOX/BV). Radiologic response: 1 CR, 39/68 (57%) PR, 27/68 (40%) SD, and 1 PD. Median OS is not reached. At a median follow-up of 32.0 months (mo) (range: 2.3–47.8 mo), the median PFS was 12.4 mo (95% CI: 9.8–15.2). Kras mutation was identified in 39 pts (57%). RR was 64% in pts with wt Kras and 52% in pts with mutant Kras (p=0.33). PFS was significantly longer for pts with wt kras compared to pts with mutant kras (13.7 mo [95% CI: 6.9–13.2] versus 8.3 mo [95%CI: 6.9–13.2], P=0.039). High EGFR (median PFS: 15.2 mo; 95% CI 11.7–16.5 mo), high VEGFR2 (median PFS: 13.9 mo; 95% CI 11.0–16.5 mo), and low ERCC1 (median PFS: 12.4 mo; 95% CI 10.9–16.4 mo) were associated with longer PFS compared to low EGFR (median PFS: 7.9 mo; 95% CI 6.9–11.0 mo, P=0.040), low VEGFR2 (median PFS: 7.2 mo; 95% CI 6.5–8.1 mo, P=0.032), and high ERCC1 (median PFS: 9.6 mo; 95% CI 5.8–15.2 mo, P=0.045). Conclusions: To our knowledge, this is the first report of a potential association between Kras status as well as gene expression levels of VEGFR2, ERCC-1 and EGFR and clinical outcome to FOLFOX/BV therapy in pts with mCRC. Prospective clinical trials are needed to validate these results.

[Table: see text]

Pharmacogenetic analysis in metastatic colorectal cancer (mCRC) patients (pts) treated with second-line irinotecan (IR)+/− cetuximab (CB): The EPIC experience

4022

Background: EPIC, a multinational phase III clinical trial with IR + CB vs IR alone in mCRC pts in the second-line setting after failure of FOLFOX demonstrated a benefit for IR+CB in progression-free survival (PFS) and response rate (RR). We evaluated functional germline polymorphisms involved in the EGFR- (EGF, EGFR), angiogenesis- (VEGF, IL-8, CXCR-2) - and drug- metabolism related genes (UGT1A1, MTHFR) for their potential role as molecular predictors for clinical outcome in pts treated with CB/IR vs. IR alone. Methods: DNA was extracted from all available formalin-fixed paraffin-embedded tumor samples from the phase III EPIC trial (US sites only). Genotyping was performed using PCR-RFLP assays and 5’ -end [g-33P] ATP’ labeled PCR-protocols. Results: 186 pts were treated either with IR/CB (arm A, 84 pts) or IR (arm B, 102 pts) only. In arm A, 11/84 pts (13%) showed CR or PR, whereas 73/84 (87%) pts had SD or PD. For arm B, 6/102 pts (6%) showed CR or PR, whereas 96/102 pts (94%) had SD or PD. Median PFS in arm A was 3.0 months (95%CI: 2.4- 4.1 months) vs 2.7 months (95%CI: 2.2–2.9 months) in arm B; median overall survival (OS) was 9.3 months (95%CI: 7.1–12.1 months) in arm A vs. 12.3 months (95%CI: 10.4- 17.9 months) in arm B. K-ras mutation status was not significantly associated with PFS or response to CB/IR in the subgroup of 186 patients. We found an EGFR-CA- repeat in intron 1 in arm A to be associated with PFS (p=0.031, log-rank test). In arm B, we found a significant association with RR (p=0.0103, Fisher's exact test) for MTHFR1298. Furthermore, MTHFR 677 (p =0.0048, log-rank test) and MTHFR 1298 (p=0.038, log-rank test) were also found to be associated with OS in arm B. In multivariate analysis, EGFR-CA-repeat was significantly associated with PFS (adjusted p= 0.023). Furthermore, MTHFR 677 and MTHFR 1298 was associated with OS (adjusted p=0.028 and 0.026, respectively, Cox-proportional hazards models), independent from K-ras mutation status, race and number of disease sites. Conclusions: Our study demonstrates the potential predictive value of polymorphisms in the EGFR- and MTHFR- gene in mCRC pts treated with IR+ CB. Further validation in additional clinical trials is necessary.

[Table: see text]

Small molecule pan-bcl-2 inhibitor AT-101 induces apoptosis in NSCLC by up-regulating noxa and enhances antitumor activity of docetaxel or targeted kinase inhibitors

e14591

Background: AT-101 is an orally active pan Bcl-2 inhibitor currently under clinical development in Phase II trials. We investigated the effect of AT-101 alone or in combination with chemotherapies or targeted kinase inhibitors in NSCLC both in vitro and in vivo. Methods: Growth inhibition was measured by WST assays. The CalculSyn method was used to assess drug interaction by calculating the Combination Index (CI) value. The ability of AT-101 to potentiate the anti-cancer effect of chemotherapies or kinase inhibitors was evaluated in xenograft models. Results: A panel of 11 NSCLC cell lines with overexpression of Bcl-2, Bcl- XL or Mcl-1 proteins was treated with AT-101, docetaxel, pemetrexed, erlotinib, sorafenib, sunitinib, rapamycin, as a single agent and in combination. AT-101 inhibited the growth with IC50 at 3–9 uM. When treating cells simultaneously with both agents, AT-101 demonstrated strong synergy with those agents in A549 or H460 cells with CI values < 1.0. Protein analysis results indicated that AT-101 caused apoptosis by a time- and dose-dependent induction of Noxa expression in those cells. The expression of Bcl- XL was not influenced by AT-101. Pro-Caspase-3 was reduced with increasing doses of AT-101. In vivo, combined treatment of AT-101 with docetaxel, erlotinib, or sorafenib synergistically suppressed subcutaneous NSCLC A549 cells tumor growth compared with treatment with either agent alone. The synergist effects with the ErbB1 inhibitor Erlotinib is associated with the overexpression of the target protein ErbB1 in those cells. Only combination therapy resulted in significant tumor growth delay and no significant toxicities were observed. Conclusions: Our results demonstrate that AT-101significantly enhances the anti-tumor activity of chemotherapy and targeted agents and may represent a promising new anticancer agent with a novel molecular mechanism. Molecular targeted therapy with AT-101 may improve the outcome of current chemotherapy for NSCLC with Bcl-2, Bcl-xL and/or Mcl-1 overexpression.

[Table: see text]

Gender disparities in hepatocellular cancer survival

e15517

Background: Recent reports suggest that estrogen mediated inhibition of IL-6 protects against the development of HCC and may explain the decreased risk of liver cancer in women. We investigated the relation-hip between gender, age, and survival for patients with localized HCC. Methods: We identified 11,097 patients with localized, histologically defined HCC, from 1988- 2003, using the Surveillance, Epidemiology, and End Results (SEER) registry. Age at diagnosis, sex, ethnicity, and overall survival were evaluated using Cox proportional hazards model. The models were adjusted for treatment modality, tumor differentiation, tumor size, lymph node involvement, and number of lesions; they were stratified by year of diagnosis and SEER registry site. Results: 8,111 (73%) patients were men and 2,986 (27%) were women. In univariate and multivariate analyses, female gender, young age (< 55 yo), and Asian ethnicity were all associated with improved overall survival (p<0.001). In patients less than 55 yo, women had a superior OS and cancer specific survival (CSS) when compared to men (OS: 18 months vs. 9, CSS: 31 months vs. 14, p<0.001). Conversely, in patients older than 55, there were no gender differences (OS: 8 months vs. 8, CSS 13 months vs. 11, p = 0.08). Local therapies, including, ablation (HR = 0.47 [0.43–0.53]), hepatectomy (HR = 0.40 [0.36–0.44]), radiation (HR = 0.67 [0.57–0.78]) and transplantation (HR = 0.17 [0.15–0.20]) were also associated with improved survival. There were no interactions identified between gender and treatment use. Conclusions: To our knowledge, this is the first report to highlight the superior outcome of premenopausal women with HCC compared to men. We postulate a potential role for estrogen in influencing the biology of HCC and the response to treatment. These observations are consistent with ones made in other gastrointestinal cancers and with reported preclinical data suggesting a protective role for estrogen. Further studies that confirm these observations and elucidate the biology of estrogen's influence on HCC are needed.

[Table: see text]

No significant financial relationships to disclose.

Effect of gender and age on overall survival in patients with esophageal cancer

4541

Background: The American Cancer Society estimated that during 2008 approximately 16,470 new esophageal cancer cases would be diagnosed in the United States. Previous studies indicate that the incidence of esophageal cancer is more in males than females; however the influence of sex in the progression of esophageal cancer is not clearly understood. In vitro and in vivo models showed that administration of estradiol significantly inhibited the growth of ER-positive and AR-positive KSE-1 tumors in both males and females in conjunction with an increase in the estradiol levels and a decrease in the DHT levels in the serum. Thus we tested the clinical significance of sex in the overall survival of esophageal cancer using SEER data. Methods: A total of 21,584 patients with localized and metastatic esophageal cancer from 1988–2004 were screened using the SEER registry. The patients were divided into age at diagnosis, sex and ethnicity. The analysis for overall survival was based on the Cox proportional hazards model adjusted for marital status, site of primary tumor, treatment, histology and tumor grade and stratified by year of diagnosis and SEER registry site. Pairwise interactions (age and sex, age and race, and sex and race) were also examined. Results: Females with localized esophageal cancer had significantly longer overall survival compared to males (p<0.001). In metastatic esophageal cancer, females seemed to have longer overall survival than males (p=0.054). Overall survival decreased with increasing age (p<0.001). African Americans with localized esophageal cancer have worse median overall survival compared to Caucasians (p<0.001). No significant difference was noted with respect to ethnicity in metastatic esophageal cancer (p=0.22). Also pairwise interactions did not have significant difference. Conclusions: This is the first and largest study showing gender as an independent prognostic factor in patients with localized and metastatic esophageal cancer. Females had a significant better overall survival than males in esophageal cancer suggesting that sex hormone pathways may have a potential impact on tumor progression. These data warrant further studies to explore the role of these pathways in the diagnosis and treatment of esophageal cancer.

No significant financial relationships to disclose.

Association of CD133 polymorphisms and clinical outcome in metastatic colorectal cancer (mCRC) patients (pts) treated with either first-line 5-FU + bevacizumab (BV) or second-line irinotecan (IR)/cetuximab (CB) or IR alone

4062

Background: CD133 has been routinely used to identify colon cancer stem cells. A recent study indicated that elevated levels of CD133 plasma mRNA correlated with colon cancer recurrence. Furthermore plasma levels of CD133+ progenitor cells have been found to be decreased after treatment with BV. We tested whether potentially functional frequently occurring germline variations in the 3’UTR-region of the CD133 gene (rs2240688, rs3130 and rs2286455), might be associated with clinical outcome in first- and second-line treated mCRC pts. Methods: Genomic DNA was extracted either from peripheral blood (79 pts, who were enrolled in a phase-II clinical trial with FOLFOX/BV or XELOX/BV) or formalin-fixed paraffin-embedded tumor samples (186 pts, who were enrolled in the EPIC phase III clinical trial, US-sites only) of mCRC pts. Pts received either first-line treatment with FOLFOX/ BV (33 pts) or XELOX/BV (46 pts) or second-line treatment with CB/IR (84 pts, arm A) or IR (102 pts, arm B) alone. Genotyping was performed using PCR-RFLP assays. Results: 79 pts (47 men, 32 women) received FOLFOX/BV or XELOX/BV. Radiologic response: 43 pts (54%) CR/PR, 35 pts (45%) SD/PD. Median PFS was 10.8 months (95%CI: 8.1–14.9). The second cohort consisted of 186 pts (103 men, 83 women). Radiologic response: Arm A 11 pts (13%) CR/PR, 73 pts (87%) SD/PD. Arm B 6 pts (6%) CR/PR, 96 pts (94%) SD/PD. Median PFS (arm A) was 3.0 months (95%CI: 2.4–4.1) vs. 2.7 months (arm B,95%CI: 2.2–2.9). Combined analysis of rs2286455 and rs3130 showed a significant association with PFS (p= 0.010, log-rank test) in pts receiving FOLFOX/BV or XELOX/BV. In pts receiving IR alone rs2240688 was significantly associated with OS (p=0.0128, log-rank test). Multivariate analysis showed a significant association with PFS in first-line setting for rs2286455 and rs3130 (adjusted p=0.012) and a trend in second-line setting for rs2240688 (adjusted p=0.086). Conclusions: These are the first data to show that polymorphisms in CD133 predict outcome in mCRC pts in first- and second- line setting, suggesting that CD133 may be a potential predictive marker. These results need to be confirmed in larger prospective studies.

[Table: see text]

Molecular profiling in patients (pts) with upper gastrointestinal (UGI) cancers correlated with clinical outcome

e22042

Background: Recent efforts have expanded our understanding of the molecular pathogenesis of UGI cancers and how oncogenes and tumor suppressor genes play a role in both carcinogenic and metastatic processes. These markers may serve as prognostic and/or predictive factors for recurrence following resection and resistance to radiotherapy and chemotherapy. Gene expression levels of thymidylate synthase (TS), thymidylate phosphorylase (TP), epidermal growth factor receptor (EGFR) and excision repair cross complementing (ERCC-1) have been shown to be associated with outcomes in lung, gastric and colon cancer. We evaluated TS, ERCC-1, EGFR and TP gene expression levels in patients with UGI cancers. Methods: This was a retrospective study of 80 pts with UGI cancers evaluated at USC who underwent molecular profiling. The primary objective was to determine a correlation between TS, TP, ERCC1 and EGFR and correlate with clinical outcome. Characteristics of these 80 pts: (16 females, 64 males ); median age 61 years (range 34–85); tumor types evaluated - 32 (40%) esophageal, 24(30%) gastric, 24(30%) GE junction; stages- 53 % IV, 21% III, 12% II, 2% I were evaluated for intratumoral gene expression of TS, TP, ERCC-1, & EGFR by real time quantitative PCR using Taqman technology from microdisected paraffin-embedded tumor sections. Results: High TS expression was associated with shorter OS (12.8 months vs. 23.7 months p=0.036). A significant correlation was found between TP & ERCC-1 (p=0.0078, r=0.37); TP & TS (p=0.0128, r=0.35); TP & EGFR (p=0.0065, r=0.39); TS & ERCC-1 (p=0.0004, r=0.39); ERCC-1 & EGFR (p=0.025, r=0.30). No statistically significant relationship was found between TS & EGFR (p=0.06,r=0.25). There was no correlation of ERCC-1, TP, & EGFR with OS that reached statistical significance. Conclusions: TS mRNA levels were shown to be associated with OS in UGI tumors, consistent with data reported in colon cancer. TS gene expression was significantly associated with expression levels of ERCC-1. In addition, ERCC1 was associated with EGFR. These data show for the first time that molecular pathways of cytotoxic agents are linked to the EGFR pathway suggesting that sensitivity to fluoropyrimidines, oxaliplatin, and EGFR inhibitors may be associated.

No significant financial relationships to disclose.

Association of a germ-line variant in the K-ras 3’ untranslated region with response and progression-free survival in patients with mCRC treated with single-agent cetuximab (IMCL-0144) or in combination with cetuximab (EPIC) independent of K-ras mutation status

4061

Background: Recent studies have found K-ras mutation status predicts response to EGFR inhibitors in mCRC. An in vitro study demonstrated let-7 microRNA family can regulate RAS expression by binding to the 3’UTR of RAS gene. Chin et al found a SNP in a let-7 microRNA complementary site (LCS) in the K-ras 3’ UTR increases cancer risk in NSCLC. We tested the hypothesis whether this SNP may be associated with clinical outcome in 130 mCRC patients enrolled in IMCL-0144 trial and in 186 pts enrolled in EPIC trial independent of K-Ras mutation status in the tumor. Methods: K-ras lcs 6 SNP was tested in 130 mCRC patients enrolled in IMC-0144 phase II clinical trial (single agent cetuximab) and in 186 mCRC patients enrolled in a second line phase III trial of cetuximab plus irinotecan versus irinotecan alone (EPIC). Genomic DNA was extracted from dissected formalin fixed paraffin embedded tumor tissue and K-ras mutation status and the polymorphism were analyzed using direct sequencing and PCR-RFLP technique. Results: The G harboring allele frequency in K-ras lcs6 was 8% in IMC-0144 and 11% in EPIC. K-ras lcs6 polymorphism was significantly associated with tumor response in patients with wild type K-ras in IMC-0144. The 12 pts harboring a G allele (TG+GG) had a 42% partial response (PR) rate compared to 55 pts with TT genotype with only 9% PR.(p=0.02, Fisher's-exact test). However, pts with TT genotype enrolled in EPIC treated with CPT-11 and cetuximab with mutant K-ras had a significantly better PFS of 12 weeks (95% CI 6.4–18) compared to those harboring the a G allele with median PFS of 6.4 weeks (95% 5.7–7) (p=0.037. log-rank test). There was no association between this polymorphism and clinical outcome in patients with wild type K-ras enrolled in EPIC. In a multivariate analysis the polymorphism remained independently associated with PFS in EPIC. Conclusions: Our data suggest for the first time that the functional germline polymorphism in K-ras lcs6 may be a potential predictive marker in mCRC patients treated with cetuximab-based chemotherapy independent of K-ras mutation status. This finding warranted further confirmative clinical trials.

[Table: see text]

Phase II study of capecitabine and gemcitabine in patients with metastatic colorectal cancer (mCRC)

e15077

Background: Failing standard chemotherapy, many mCRC patients (pts) maintain an adequate performance status necessitating therapeutic options. Preclinical data in CRC cell lines shows that 5-FU and gemcitabine have synergistic cytotoxicity by stabilization of thymidylate synthase resulting in stronger inhibition of DNA synthesis. Methods: The primary objective was to assess time to progression (TTP) in mCRC pts who had progressed on irinotecan and oxaliplatin therapy. Secondary objectives included response rate (RR), overall survival (OS), toxicity and correlates to assess genes in the 5-FU, gemcitabine pathways. This single center study was a two stage minimax design. A ≤ 30% chance of progressing within the first 6 weeks would be promising. 27 pts were enrolled in the first stage, if ≥ 13 progressed (or had unacceptable toxicity) prior to 6 weeks then the study would be terminated. The planned sample size was 53 pts. A cycle was defined as capecitabine 650 mg/m2 BID days 1–14 and gemcitabine 1,000 mg/m2 i.v. over 100 minutes days 1, 8. Results: The study met its first stage goal and continued to accrue 54 eligible pts (male 24/female 30), median age 58 years (range 31–78). Pts received a median of 2 cycles (range 1–19), with 22% of pts receiving 6 + cycles. Three pts that withdrew shortly after start were excluded from toxicity analysis. Of 51 pts, 23 had Grade 3/4 drug related toxicity, commonly 9 pts ANC/AGC; 4 pts pain. The probability of progressing at 6 weeks was .46 + .07, with 23 pts progressing or dying within that time. Median OS was 5.9 months (95% CI 4.3, 8.7), PFS was 8.1 weeks (95% CI 5.6, 11.6). Of 48 pts evaluable for response, 17 had stable disease, for these pts, the median PFS was 4.3 months (95%CI: 3.9–8.8) and OS 10 months (95%CI: 7.9–16.6); 31 had progressive disease or symptomatic deterioration. Conclusions: The combination of gemcitabine and capecitabine in refractory mCRC was well tolerated. Unfortunately, the study did not meet the primary endpoint, but there appears to be a subset of pts with stable disease who may benefit from therapy. Correlatives are pending.

[Table: see text]