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BACKGROUND: In the phase II multicohort CheckMate 142 study, nivolumab plus low-dose (1 mg/kg) ipilimumab provided robust and durable clinical benefit with a manageable safety profile in previously treated patients with microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) metastatic colorectal cancer (mCRC) at 13.4- and 25.4-month median follow-up (Overman MJ, Lonardi S, Wong KYM et al. Durable clinical benefit with nivolumab plus ipilimumab in DNA mismatch repair-deficient/microsatellite instability-high metastatic colorectal cancer. J Clin Oncol. 2018;36:773-779. Overman MJ, Lonardi S, Wong KYM, et al. Nivolumab plus low-dose ipilimumab in previously treated patients with microsatellite instability-high/mismatch repair deficient metastatic colorectal cancer: long-term follow-up. J Clin Oncol. 2019;37:635). Here, we present results from the 4-year follow-up of these patients. PATIENTS AND METHODS: Patients received nivolumab (3 mg/kg) plus low-dose (1 mg/kg) ipilimumab every 3 weeks (four doses) followed by nivolumab (3 mg/kg) every 2 weeks until disease progression. Primary endpoint was investigator-assessed objective response rate (ORR; as per RECIST version 1.1). RESULTS: A total of 119 patients were treated; 76% had ≥2 prior lines of therapy. Median follow-up was 50.9 months (range 46.9-62.7 months). Median duration of therapy was 24.9 months [95% confidence interval (CI) 15.8-33.2 months]. Investigator-assessed ORR increased from 55% (95% CI 45% to 64%) at 13.4 months to 65% (95% CI 55% to 73%) at 50.9 months with a disease control rate of 81% (95% CI 72% to 87%). The complete response rate increased from 3% at 13.4 months to 13% at 50.9 months. Partial responses were observed in 52% of patients; 21% had stable disease, and 12% had progressive disease. Median time to response was 2.8 months (range 1.1-37.1 months), and median duration of response was not reached (range 1.4+ to 58.0+ months). At data cut-off, 37 (48%) patients had ongoing responses. Median progression-free survival was not reached [95% CI 38.4 months-not estimable (NE)], and median overall survival was not reached (95% CI NE). Grade 3-4 treatment-related adverse events (TRAEs) were observed in 32% of patients; 13% of patients had any-grade TRAEs leading to discontinuation. CONCLUSIONS: The results confirm long-term benefit of nivolumab plus low-dose ipilimumab for previously treated patients with MSI-H/dMMR mCRC. The safety profile was manageable with no new safety signals. ispartof: ANNALS OF ONCOLOGY vol:33 issue:10 pages:1052-1060 ispartof: location:England status: published

INTRODUCTION: The oral fluoropyrimidine S-1 has shown comparable efficacy to capecitabine in Asian and some Western studies on metastatic colorectal cancer. S-1 is associated with a lower incidence of hand-foot syndrome (HFS) and cardiac toxicity. We assessed the long-term tolerability of S-1 in patients who discontinued capecitabine for reasons of HFS or cardiac toxicity.PATIENTS AND METHODS: Patients with metastatic colorectal cancer who switched from capecitabine to S-1, given as monotherapy or in combination with other agents, were identified in a Dutch prospective cohort study (2016-2021). The incidence and severity of HFS, cardiotoxicity and other toxicities were assessed.RESULTS: Forty-seven patients were identified. The median duration of capecitabine treatment was 81 days (range 4-454). In 19 patients (40%) a dose reduction was applied prior to switch to S-1. Reasons for discontinuation of capecitabine were HFS in 36 (77%) patients, coronary artery vasospasms in 10 (21%) patients, and gastrointestinal toxicities in 1 patient (2%). The median number of S-1 cycles was 6 (range 1-36). The median time between last dose of capecitabine and first dose of S-1 was 11 days (range 1-49). After switch to S-1, all patients with prior HFS developed a lower grade or complete resolution of symptoms, and in all other patients symptoms did not recur. Other S-1-related adverse events were limited to grade 1-2. Six patients (13%) discontinued S-1 due to either known fluoropyrimidine-related or bevacizumab-related toxicities. Switch to S-1 did not appear to compromise treatment efficacy.CONCLUSION: S-1 is a valid alternative to capecitabine in case HFS or cardiotoxicity occurs.

INTRODUCTION: The RECOURSE trial demonstrated a modest benefit in overall survival (OS) for trifluridine/tipiracil (FTD/TPI) versus placebo in pretreated metastatic colorectal cancer (mCRC) patients. Unfortunately, quality of life (QoL) was not assessed. We evaluated QoL and survival of patients treated with FTD/TPI in daily practice.PATIENTS AND METHODS: QUALITAS is a substudy of the Prospective Dutch CRC cohort (PLCRC). From 150 mCRC patients treated with FTD/TPI, QoL (EORTC QLQ-C30 and QLQ-CR29) was assessed monthly from study entry, and linked to clinical data of the Netherlands Cancer Registry. Joint models were constructed combining mixed effects models with Cox PH models. Primary endpoint was difference in QoL over time (which was deemed clinically relevant if ≥10 points). Secondary endpoints were progression-free survival (PFS), time to treatment failure (TTF), and OS. We analyzed the association between QLQ-C30 Summary Score (QoL-SS) at FTD/TPI initiation (baseline) and survival.RESULTS: There was no clinically relevant change in QoL-SS from baseline to 10 months post-baseline (i.e. the cut-off point after which 90% of patients had discontinued FTD/TPI treatment): -5.3 [95% CI -8.7;-1.5]. Patients who were treated with FTD/TPI for ≥ 3 months (n = 85) reported 6.3 [1.6;11.1] points higher baseline QoL, compared to patients treated < 3 months (n = 65, "poor responders"). In the latter, time to a clinically relevant QoL deterioration was < 2 months. Median PFS, TTF and OS were 2.9 [2.7;3.1], 3.1 [2.9;3.2] and 7.7 [6.6;8.8] months, respectively. Worse baseline QoL-SS was independently associated with shorter OS (HR 0.45 [0.32;0.63]), PFS (0.63 [0.48;0.83]), and TTF (0.64 [0.47;0.86]).CONCLUSION: The maintenance of QoL during FTD/TPI treatment in daily practice supports its use. The QoL deterioration in "poor responders" is likely due to disease progression. The strong association between worse baseline QoL and shorter survival suggests that clinicians should take QoL into account when determining prognosis and treatment strategy for individual patients.

Background: Trifluridine–tipiracil plus bevacizumab has shown efficacy in previous phase 2 studies including patients with unresectable metastatic colorectal cancer. We aimed to investigate first-line trifluridine–tipiracil plus bevacizumab versus capecitabine plus bevacizumab in patients with unresectable metastatic colorectal cancer ineligible for intensive treatment. Methods: In this open-label, randomised, phase 3 study, we enrolled patients aged 18 years and older with histologically confirmed metastatic colorectal cancer, ineligible for full-dose doublet or triplet chemotherapy and curative resection across 25 countries and regions. Participants were randomly allocated (1:1) to trifluridine–tipiracil plus bevacizumab or capecitabine plus bevacizumab until disease progression or unacceptable toxicity using an interactive web response system, stratified by Eastern Cooperative Oncology Group (ECOG) performance status (0 vs 1 vs 2), primary tumour location (right vs left colon), and the main reason for not being a candidate for intensive therapy (clinical condition vs non-clinical condition). The primary endpoint was investigator-assessed progression-free survival, defined as the time from randomisation to radiological progression or death from any cause, in the intention-to-treat population. Safety was assessed in all patients having taken at least one dose of the study drug. The trial is ongoing, findings presented here are those of the primary analysis of progression-free survival, conducted after 629 events had occurred. This study is registered with ClinicalTrials.gov, NCT03869892. Findings: Between March 21, 2019, and Sept 14, 2020, 856 patients (54% male, 46% female) were randomly assigned to trifluridine–tipiracil plus bevacizumab (n=426) or capecitabine plus bevacizumab (n=430). After a median follow-up of 16·6 months (95% CI 16·5–17·1), the hazard ratio for progression-free survival for trifluridine–tipiracil plus bevacizumab versus capecitabine plus bevacizumab was 0·87 (0·75–1·02; p=0·0464; protocol-defined significance level of p=0·021 not met). Investigator-assessed median progression-free survival was 9·4 months (95% CI 9·1–10·9) with trifluridine–tipiracil plus bevacizumab versus 9·3 months (8·9–9·8) with capecitabine plus bevacizumab. The most common grade 3 and higher treatment-emergent adverse events were neutropenia (220 [52%] of 423 patients in the trifluridine–tipiracil plus bevacizumab group vs six [1%] of 427 in the capecitabine plus bevacizumab group), decreased neutrophil count (78 [18%] vs four [

Funding: The authors thank the financial support from Fundação para a Ciência e Tecnologia (FCT) through projects UIDB/00100/2020, UIDP/00100/2020, UIDB/04138/2020, UIDP/04138/2020, LA/P/0056/2020, and PTDC/QUI-QIN/0586/2020. N. Ribeiro acknowledges FCT for the SFRH/BD/ 135797/2018 grant. Andreia Ferreira acknowledges FCT for the PD/BD/135506/2018 grant. Colorectal cancer is the second leading cause of cancer-related mortality. Many current therapies rely on chemotherapeutic agents with poor specificity for tumor cells. The clinical success of cisplatin has prompted the research and design of a huge number of metal-based complexes as potential chemotherapeutic agents. In this study, two zinc(II) complexes, [ZnL 2] and [ZnL(AcO)], where AcO is acetate and L is an organic compound combining 8-hydroxyquinoline and a benzothiazole moiety, were developed and characterized. Analytical and spectroscopic studies, namely, NMR, FTIR, and UV-Vis allowed us to establish the complexes' structures, demonstrating the ligand-binding versatility: tetradentate in [ZnL(AcO)] and bidentate in [ZnL 2]. Complexes were screened in vitro using murine and human colon cancer cells cultured in 2D and 3D settings. In 2D cells, the IC 50 values were

Background Patients with BRAF V600E mutated metastatic colorectal cancer (mCRC) have a poor prognosis. The introduction of BRAF targeted therapy with encorafenib and weekly administered cetuximab have shown improved survival with a median progression free survival (PFS) of 4.3 months. However, a regimen with cetuximab given every second week may have comparable efficacy and is more convenient for patients. While BRAF targeted therapy is a new standard therapy in pre-treated patients with BRAF V600E mutated mCRC, resistance invariably occurs and is an emerging challenge. The aim of this study is to investigate the efficacy and tolerability of cetuximab given every second week in combination with daily encorafenib and to explore the correlation between markers of resistance and outcome. Methods The study is an open label, single arm, phase II study, investigating the efficacy and tolerability of cetuximab given every second week in combination with encorafenib in patients with BRAF V600E mutated mCRC. Furthermore, we will be investigating mechanisms of response and resistance against BRAF targeted therapy though comprehensive genomic profiling on tumor tissue and blood for circulating tumor DNA analysis. A total of 53 patients (19 + 34 in two steps) will be included according to Simon’s optimal two stage design. The primary end point of the study is 2 months PFS rate. Discussion By combining BRAF inhibitor with cetuximab given every second week we can halve the number of visits in the hospital compared to the currently approved regimen with weekly cetuximab. This seems particularly relevant in a group of patients with a median overall survival of 9.3 months. Resistance after initial response to targeted therapy can be either adaptive (e.g., epigenetic, or transcriptomic alterations) or acquired (selective genetic alterations - e.g., activating de novo mutations) resistance. It is of great importance to untangle these complex mechanisms of resistance in patients with BRAF V600E mutated mCRC to improve treatment strategies in the future potentially even further. Trial registration EU Clinical Trial Register, Eudract no. 2020-003283-10. Registered on 11 November 2020.

Embargo 12 kk The inability of traditional chemotherapeutics to reach cancer tissue reduces the treatment efficacy and leads to adverse effects. A multifunctional nanovector was developed consisting of porous silicon, superparamagnetic iron oxide, calcium carbonate, doxorubicin and polyethylene glycol. The particles integrate magnetic properties with the capacity to retain drug molecules inside the pore matrix at neutral pH to facilitate drug delivery to tumor tissues. The MRI applicability and pH controlled drug release were examined in vitro together with in-depth material characterization. The in vivo biodistribution and compound safety were verified using A549 lung cancer bearing mice before proceeding to therapeutic experiments using CT26 cancer implanted mice. Loading doxorubicin into the porous nanoparticle negated the adverse side effects encountered after intravenous administration highlighting the particles’ excellent biocompatibility. Furthermore, the multifunctional nanovector induced 77% tumor reduction after intratumoral injection. The anti-tumor effect was comparable with that of free doxorubicin but with significantly alleviated unwanted effects. These results demonstrate that the developed porous silicon-based nanoparticles represent promising multifunctional drug delivery vectors for cancer monitoring and therapy.

Colorectal cancer is a molecularly heterogeneous disease. Responses to genotoxic chemotherapy in the adjuvant or palliative setting vary greatly between patients, and colorectal cancer cells often resist chemotherapy by evading apoptosis. Antagonists of an inhibitor of apoptosis proteins (IAPs) can restore defective apoptosis signaling by degrading cIAP1 and cIAP2 proteins and by inhibition of XIAP. Due to the multiple molecular mechanisms-of-action of these targets, responses to IAP antagonist may differ between molecularly distinct colon cancer cells. In this study, responses to the IAP antagonist Birinapant and oxaliplatin/5-fluorouracil (5-FU) were investigated in 14 colon cancer cell lines, representing the consensus molecular subtypes (CMS). Treatment with Birinapant alone did not result in a substantial increase in apoptotic cells in this cell line panel. Annexin-V/PI assays quantified by flow cytometry and high-content screening showed that Birinapant increased responses of CMS1 and partially CMS3 cell lines to oxaliplatin/5-FU, whereas CMS2 cells were not effectively sensitized. FRET-based imaging of caspase-8 and -3 activation validated these differences at the single-cell level, with CMS1 cells displaying sustained activation of caspase-8-like activity during Birinapant and oxaliplatin/5-FU co-treatment, ultimately activating the intrinsic mitochondrial apoptosis pathway. In CMS2 cell lines, Birinapant exhibited synergistic effects in combination with TNFα, suggesting that Birinapant can restore extrinsic apoptosis signaling in the context of inflammatory signals in this subtype. To explore this further, we co-cultured CMS2 and CMS1 colon cancer cells with peripheral blood mononuclear cells. We observed increased cell death during Birinapant single treatment in these co-cultures, which was abrogated by anti-TNFα-neutralizing antibodies. Collectively, our study demonstrates that IAP inhibition is a promising modulator of response to oxaliplatin/5-FU in colorectal cancers of the CMS1 subtype, and may show promise as in the CMS2 subtype, suggesting that molecular subtyping may aid as a patient stratification tool for IAP antagonists in this disease.

Activation of the mitogen-activated protein kinase (MAPK) pathway is frequent in cancer. Drug development efforts have been focused on kinases in this pathway, most notably on RAF and MEK. We show here that MEK inhibition activates JNK-JUN signaling through suppression of DUSP4, leading to activation of HER Receptor Tyrosine Kinases. This stimulates the MAPK pathway in the presence of drug, thereby blunting the effect of MEK inhibition. Cancers that have lost MAP3K1 or MAP2K4 fail to activate JNK-JUN. Consequently, loss-of-function mutations in either MAP3K1 or MAP2K4 confer sensitivity to MEK inhibition by disabling JNK-JUN-mediated feedback loop upon MEK inhibition. In a panel of 168 Patient Derived Xenograft (PDX) tumors, MAP3K1 and MAP2K4 mutation status is a strong predictor of response to MEK inhibition. Our findings suggest that cancers having mutations in MAP3K1 or MAP2K4, which are frequent in tumors of breast, prostate and colon, may respond to MEK inhibitors. Our findings also suggest that MAP3K1 and MAP2K4 are potential drug targets in combination with MEK inhibitors, in spite of the fact that they are encoded by tumor suppressor genes.

BackgroundMutations inKRASare frequent in human cancer, yet effective targeted therapeutics for these cancers are still lacking. Attempts to drug the MEK kinases downstream of KRAS have had limited success in clinical trials. Understanding the specific genomic vulnerabilities ofKRAS-driven cancers may uncover novel patient-tailored treatment options.MethodsWe first searched for synthetic lethal (SL) genetic interactions with mutantRASin yeast with the ultimate aim to identify novel cancer-specific targets for therapy. Our method used selective ploidy ablation, which enables replication of cancer-specific gene expression changes in the yeast gene disruption library. Second, we used a genome-wide CRISPR/Cas9-based genetic screen inKRASmutant human colon cancer cells to understand the mechanistic connection between the synthetic lethal interaction discovered in yeast and downstream RAS signaling in human cells.ResultsWe identify loss of the endoplasmic reticulum (ER) stress sensorIRE1as synthetic lethal with activatedRASmutants in yeast. InKRASmutant colorectal cancer cell lines, genetic ablation of the human ortholog ofIRE1,ERN1, does not affect growth but sensitizes to MEK inhibition. However, an ERN1 kinase inhibitor failed to show synergy with MEK inhibition, suggesting that a non-kinase function of ERN1 confers MEK inhibitor resistance. To investigate how ERN1 modulates MEK inhibitor responses, we performed genetic screens inERN1knockoutKRASmutant colon cancer cells to identify genes whose inactivation confers resistance to MEK inhibition. This genetic screen identified multiple negative regulators of JUN N-terminal kinase (JNK) /JUN signaling. Consistently, compounds targeting JNK/MAPK8 or TAK1/MAP3K7, which relay signals from ERN1 to JUN, display synergy with MEK inhibition.ConclusionsWe identify the ERN1-JNK-JUN pathway as a novel regulator of MEK inhibitor response inKRASmutant colon cancer. The notion that multiple signaling pathways can activate JUN may explain whyKRASmutant tumor cells are traditionally seen as highly refractory to MEK inhibitor therapy. Our findings emphasize the need for the development of new therapeutics targeting JUN activating kinases, TAK1 and JNK, to sensitizeKRASmutant cancer cells to MEK inhibitors.

BACKGROUND: Neoadjuvant chemotherapy represents a new treatment approach to locally advanced colon cancer. The aim of this study was to analyze the ability of tumor-stroma ratio (TSR) to predict disease recurrence in patients with locally advanced colon cancer treated with neoadjuvant chemotherapy.MATERIAL AND METHODS: This study included 65 patients with colon cancer treated with neoadjuvant chemotherapy in a phase II trial. All patients were planned for three cycles of capecitabine and oxaliplatin before surgery. Hematoxylin and eosin stained tissue sections from surgically resected primary tumors were sampled and analyzed by conventional microscopy. Patients were divided into stroma-high (>50%, i.e. TSR low) and stroma-low (≤50%, i.e. TSR high) for the comparison with clinical data.RESULTS: A low TSR was found in 47% of the surgically resected primary tumors and correlated to a significantly higher T- and N-category compared, to tumors with a high TSR (p CONCLUSIONS: TSR assessed in the surgically resected primary tumor from patients with locally advanced colon cancer treated with neoadjuvant chemotherapy provides prognostic value and may serve as a relevant parameter in selecting patients for post-operative treatment.

Background. Adjuvant chemotherapy is established routine therapy for colon cancer (CC) patients with radically resected stage III and 'high-risk' stage II disease. The decision on recommending adjuvant chemotherapy, however, is based on data from older patient cohorts not reflecting improvements in pre-operative staging, surgery, and pathological examination. The aim is to review the current risk of recurrence in stage II and III patients and second, to estimate the relative importance of routinely assessed clinico-pathological variables. Methods. The PubMed/MEDLINE and the Cochrane databases were systematically searched for randomized controlled studies and observational studies published after 1 January 2005 with patients included after January 1995 on prognosis in surgically treated stage II and III CC patients. Results. Of 2596 studies identified, 37 met the inclusion criteria and 25 provided data for meta-analysis. The total patient sample size in the 25 studies reporting either disease-free (DFS) or recurrence-free survival was 15 559 in stage II and 18 425 in stage III. Five-year DFS for stage II patients operated without subsequent adjuvant chemotherapy was 81.4% [95% confidence interval (CI) 75.4-87.4; in studies with good/very good quality of reporting 82.7%, (95% CI 80.8-84.6)]. For stage II patients treated with adjuvant chemotherapy, the five-year DFS was 79.3% (95% CI 75.6-83.1). For stage III patients without chemotherapy, five-year DFS was 49.0% (95% CI 23.2-74.8) and for those treated with adjuvant chemotherapy, 63.6% (95% CI 59.3-67.9). The prognostic impact of commonly investigated clinico-pathological parameters, (pT-stage, pN-stage, differentiation, number of lymph nodes studied, MMR-status, and emergency surgery) were confirmed. Conclusions. In this meta-analysis, studies with good quality of reporting show a FIVE-year DFS of 82.7% for stage II CC without adjuvant chemotherapy, whereas the FIVE-year DFS is 63.8% for stage III CC with adjuvant chemotherapy. Due to insufficient reporting on treatment quality the presented DFS is likely an under-estimation of what is achieved at high-quality centers today.

Purpose This study evaluates whether gene signatures for chemosensitivity for irinotecan and 5-fluorouracil (5-FU) derived from in vitro grown cancer cell lines can predict clinical sensitivity to these drugs. Methods To test if an irinotecan signature and a SN-38 signature could identify patients who benefitted from the addition of irinotecan to 5-FU, we used gene expression profiles based on cell lines and clinical tumor material. These profiles were applied to expression data obtained from pretreatment formalin fixed paraffin embedded (FFPE) tumor tissue from 636 stage III colon cancer patients enrolled in the PETACC-3 prospective randomized clinical trial. A 5-FU profile developed similarly was assessed by comparing the PETACC-3 cohort with a cohort of 359 stage II colon cancer patients who underwent surgery but received no adjuvant therapy. Results There was no statistically significant association between the irinotecan or SN-38 profiles and benefit from irinotecan. The 5-FU sensitivity profile showed a statistically significant association with relapse free survival (RFS) (hazard ratio (HR) = 0.54 (0.41–0.71), p

Background The mammalian target of rapamycin (mTOR) is frequently activated in colon cancers due to mutations in the phosphatidylinositol 3-kinase (PI3K) pathway. Targeting mTOR with allosteric inhibitors of mTOR such as rapamycin reduces colon cancer progression in several experimental models. Recently, a new class of mTOR inhibitors that act as ATP-competitive inhibitors of mTOR, has been developed. The effectiveness of these drugs in colon cancer cells has however not been fully characterized. Methods LS174T, SW480 and DLD-1 colon cancer cell lines were treated with PP242 an ATP-competitive inhibitor of mTOR, NVP-BEZ235, a dual PI3K/mTOR inhibitor or rapamycin. Tumor cell growth, proliferation and survival were assessed by MTS assay, 5-bromo-2'-deoxyuridine (BrDU) incorporation or by quantification of DNA fragmentation respectively. In vivo, the anticancer activity of mTOR inhibitors was evaluated on nude mice bearing colon cancer xenografts. Results PP242 and NVP-BEZ235 reduced the growth, proliferation and survival of LS174T and DLD-1 colon cancer cells more efficiently than rapamycin. Similarly, PP242 and NVP-BEZ235 also decreased significantly the proliferation and survival of SW480 cells which were resistant to the effects of rapamycin. In vivo, PP242 and NVP-BEZ235 reduced the growth of xenografts generated from LS174T and SW480 cells. Finally, we also observed that the efficacy of ATP-competitive inhibitors of mTOR was enhanced by U0126, a MEK inhibitor. Conclusions Taken together, these results show that ATP-competitive inhibitors of mTOR are effective in blocking colon cancer cell growth in vitro and in vivo and thus represent a therapeutic option in colon cancer either alone or in combination with MEK inhibitors.

Peptides that interfere with the natural resistance of cancer cells to genotoxininduced apoptosis may improve the efficacy of anticancer regimens. We have previously reported that a cell-permeable RasGAP-derived peptide (TAT-RasGAP 317 – 326 ) specifically sensitizes tumor cells to genotoxin-induced apoptosis in vitro. Here, we examined the in vivo stability of a protease-resistant d -form of the peptide, RI·TATRasGAP 317 – 326 , and its effect on tumor growth in nude mice bearing subcutaneous human colon cancer HCT116 xenograft tumors. After intraperitoneal injection, RI·TAT-RasGAP 317 – 326 persisted in the blood of nude mice for more than 1 hour and was detectable in various tissues and subcutaneous tumors. Tumor-bearing mice treated daily for 7 days with RI·TAT-RasGAP 317 – 326 (1.65 mg/kg body weight) and cisplatin (0.5 mg/kg body weight) or doxorubicin (0.25 mg/kg body weight) displayed reduced tumor growth compared with those treated with either genotoxin alone (n = 5 – 7 mice per group; P = .004 and P = .005, respectively; repeated measures analysis of variance [ANOVA, two-sided]). This ability of the RI·TAT-RasGAP 317 – 326 peptide to enhance the tumor growth inhibitory effect of cisplatin was still observed at peptide doses that were at least 150-fold lower than the dose lethal to 50% of mice. These findings provide the proof of principle that RI·TAT-RasGAP 317 – 326 may be useful for improving the efficacy of chemotherapy in patients. J Natl Cancer Inst 2009;101: 828 – 832