Grothey, Axel

Abstract Systemic therapy has led to a median survival time for patients with advanced colorectal cancer (CRC) almost fourfold longer than that expected with best supportive care, an outcome achieved through combining chemotherapeutic and targeted biologic agents. Although the latter can include anti–epidermal growth factor receptor antibodies, such as cetuximab and panitumumab, we now have strong evidence that patients whose tumors harbor mutated KRAS will not benefit from this class of agent. Acceptance of the reliability and importance of the KRAS data took several years to evolve, however, for a variety of reasons. The timeline from the presentation and publication of small, retrospective phase II studies to widespread acceptance of the KRAS predictive value and changes in behavior—specifically, modifications of ongoing national trials in advanced/metastatic CRC, changes in national guidelines and practice patterns, and adjustments to the labeled indications for the monoclonal antibodies—was lengthy. In this commentary, we discuss whether or not the process of data disclosure regarding KRAS status and treatment of advanced CRC patients was effective in permitting timely decisions regarding ongoing publicly funded clinical trials and whether or not such decisions were rational and ethical. The overall goals are to highlight lessons learned regarding early disclosure of clinical trial results, as well as vetting and adoption of new scientific data, and to propose modifications for handling similar situations in the future.

Abstract Learning Objectives After completing this course, the reader will be able to: Explain the difference in survival prediction between response criteria (WHO) when used as a two-level variable (CR/PR vs. other) and as a three-level variable (CR/PR vs. SD vs. PD).Describe the limited benefit of using actual tumor measurements over traditional criteria (as a three-level variable) in predicting survival in colorectal cancer. This article is available for continuing medical education credit at CME.TheOncologist.com Purpose. We explored the prognostic value of actual tumor measurements (TM) versus World Health Organization (WHO) criteria as three-level (responder, stable, and progression) and two-level (responder and non-responder) variables at 12 and 24 weeks as predictors of survival in Intergroup Trial N9741, a phase III trial in metastatic colorectal cancer (CRC). Methods. All patients with measurable disease (N = 1,188) were included. The percentage changes in TM from baseline to 12 and 24 weeks were calculated. The prognostic values of TM versus WHO criteria (as three- and two-level variables) at 12 and 24 weeks were compared, using Cox models for overall survival (OS) in a landmark analysis, adjusting for baseline tumor size, performance status, and treatment arm. Results. Tumor status at 12 weeks by WHO criteria (three or two levels) or actual TM were all strongly associated with OS. Actual TM provided no meaningful additional benefit compared with the three-level WHO criteria. Tumor status at 24 weeks was also strongly associated with survival, but added no additional prognostic value compared with the 12-week assessment. At 12 weeks, actual TM improved prognostic characterization of patients with WHO status of response, but provided no additional value in patients with stable disease or progression. Conclusions. In N9741, the use of actual TM, or following tumor status beyond 12 weeks, did not improve survival prediction compared with a single three-level response assessment at 12 weeks, suggesting that 12-week tumor status could be an appropriate phase II trial endpoint in metastatic CRC.

The majority of patients with gastrointestinal cancers are over the age of 65. This age group comprises the minority of the patients enrolled in clinical trials, and it is unknown whether older patients achieve similar results as younger patients in terms of survival benefit and tolerability. In addition, there are few studies specifically designed for patients over 65 years. Subset analyses of individual trials and studies using pooled patient data from multiple trials provide some understanding on outcomes in older patients with gastrointestinal cancers. This article reviews the evidence on chemotherapeutic regimens in the elderly with colorectal, pancreatic, and gastroesophageal cancers, and discusses a practical approach to provide the best outcomes for older patients.

Purpose Cumulative sensory neurotoxicity (sNT) is the dose-limiting toxicity of oxaliplatin, which commonly leads to early discontinuation of oxaliplatin-based therapy in the palliative and adjuvant settings. In a nonrandomized, retrospective study, intravenous (IV) calcium/magnesium (Ca/Mg) was associated with reduced oxaliplatin-induced sNT. Methods Patients with colon cancer undergoing adjuvant therapy with infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX) were randomly assigned to Ca/Mg (1g calcium gluconate plus 1g magnesium sulfate pre- and post-oxaliplatin) or placebo, in a double-blinded manner. The primary end point was the percentage of patients with grade 2 or greater sNT at any time during or after oxaliplatin-based therapy by National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE; version 3) criteria. An oxaliplatin-specific sNT scale and patient questionnaires were also used to assess sNT. After 104 of 300 planned patients were enrolled, the study was closed. This was due to preliminary reports from another trial that suggested that Ca/Mg decreased treatment efficacy; these data were subsequently found to be incorrect. Results Overall, 102 patients were available for analysis. Ca/Mg decreased the incidence of chronic, cumulative, grade 2 or greater sNT, as measured by NCI CTCAE (P = .038) and also by the oxaliplatin-specific sNT scale (P = .018). In addition, acute muscle spasms associated with oxaliplatin were significantly reduced (P = .01) No effect on acute, cold-induced sNT was found. No substantial differences in adverse effects were noted between Ca/Mg and placebo. Conclusion Despite early termination and decreased statistical power, this study supports IV Ca/Mg as an effective neuroprotectant against oxaliplatin-induced cumulative sNT in adjuvant colon cancer.

Purpose Prior reports have indicated that patients with colon cancer who demonstrate high-level microsatellite instability (MSI-H) or defective DNA mismatch repair (dMMR) have improved survival and receive no benefit from fluorouracil (FU) -based adjuvant therapy compared with patients who have microsatellite-stable or proficient mismatch repair (pMMR) tumors. We examined MMR status as a predictor of adjuvant therapy benefit in patients with stages II and III colon cancer. Methods MSI assay or immunohistochemistry for MMR proteins were performed on 457 patients who were previously randomly assigned to FU-based therapy (either FU + levamisole or FU + leucovorin; n = 229) versus no postsurgical treatment (n = 228). Data were subsequently pooled with data from a previous analysis. The primary end point was disease-free survival (DFS). Results Overall, 70 (15%) of 457 patients exhibited dMMR. Adjuvant therapy significantly improved DFS (hazard ratio [HR], 0.67; 95% CI, 0.48 to 0.93; P = .02) in patients with pMMR tumors. Patients with dMMR tumors receiving FU had no improvement in DFS (HR, 1.10; 95% CI, 0.42 to 2.91; P = .85) compared with those randomly assigned to surgery alone. In the pooled data set of 1,027 patients (n = 165 with dMMR), these findings were maintained; in patients with stage II disease and with dMMR tumors, treatment was associated with reduced overall survival (HR, 2.95; 95% CI, 1.02 to 8.54; P = .04). Conclusion Patient stratification by MMR status may provide a more tailored approach to colon cancer adjuvant therapy. These data support MMR status assessment for patients being considered for FU therapy alone and consideration of MMR status in treatment decision making.

Abstract Genomics and proteomics have held out the promise of individualized medicine for the last 10 or 20 years, but clinical medicine has not yet delivered on this promise. Some cancers, such as breast cancer and some hematologic malignancies, have been at the forefront of individualized therapeutic approaches by integrating molecular biomarkers into treatment decision algorithms. Until recently, the treatment of colorectal cancer (CRC) has lagged behind these other cancers in this regard and therapeutic decisions have been solely empirical. Data from various clinical trials and translational studies have now opened the door for individualized treatment approaches by identifying patients with metastatic CRC who are most likely to benefit from antibodies against the epidermal growth factor receptor (EGFR), cetuximab and panitumumab. Activating mutations of KRAS, a downstream mediator of EGFR signaling, has been shown to render EGFR antibodies ineffective, such that analyzing tumors for these mutations has become mandatory before the use of EGFR antibodies is considered in CRC. Beyond KRAS, several additional biomarkers are currently being investigated as potential positive or negative predictors for the efficacy of EGFR-targeted therapy. Most of these markers are alterations of molecules integrated in the EGFR pathway. This review will focus on the type and quality of evidence that has been gathered to date to predict resistance to monoclonal antibodies against EGFR in CRC. (Clin Cancer Res 2009;15(24):7492–501)

Purpose We previously validated disease-free survival (DFS) as a surrogate for overall survival (OS) in fluorouracil-based adjuvant colon cancer clinical trials. New therapies have extended survival after recurrence from 1 to approximately 2 years. We examined the possible impact of this improvement on the DFS/OS association. Methods The Adjuvant Colon Cancer Endpoints (ACCENT) data set of 20,898 patients was analyzed. In an exploratory fashion, time from recurrence to death in patients experiencing recurrence was extended using several algorithms, and the association of DFS after 3 years of median follow-up and OS after varying lengths of follow-up (median of 5, 6, and 7 years) was assessed. Results Seven thousand four hundred two patients (35%) experienced recurrence. Median time from recurrence to death was 24 months in the hypothetical data sets. When times from recurrence to death were doubled, the association between treatment effects on DFS and 5-year OS was modest (R2 = 0.51 for both 2- and 3-year DFS) but remained strong for DFS and 6-year OS (R2 = 0.67 for both 2- and 3-year DFS) and 7-year OS (R2 = 0.70 for both 2- and 3-year DFS). The reduced DFS/OS association with extended survival after recurrence was greater in stage II than stage III patients. Multiple simulations provided consistent findings. Conclusion Extended survival after recurrence reduces the association between treatment effects on 3-year DFS and 5-year OS, particularly in stage II patients; longer follow-up strengthens the association. In modern adjuvant trials, 6 or 7 years may be required to demonstrate OS improvements, further supporting DFS as the preferred primary end point for future adjuvant colon cancer clinical trials.