HOXB8 mediates resistance to cetuximab in colorectal cancer cells through activation of the STAT3 pathway

Homeobox B8 (HOXB8) belongs to the HOX family and was essential to the development of colorectal carcinoma. Among the prevalent monoclonal antibodies for treating RAS/BRAF wild-type metastatic colorectal cancer (mCRC) patients, cetuximab stands out, but resistance to cetuximab frequently arises in targeted treatments. Currently, the role of HOXB8 in cetuximab-resistant mCRC remains unclear. By comparing drug-sensitive cell lines (SW48) with drug-resistant cell lines (HCT116, CACO2), we discovered that HOXB8 was substantially expressed in cetuximab-resistant cell lines, and furthermore, in drug-resistant cell lines (HCT116, CACO2), HOXB8 knockdown increased the cytotoxicity of cetuximab via blocking the signal transducer and activator of transcription 3 (STAT3) signaling pathway. Conversely, the excessive expression of HOXB8 reduced the growth suppression in SW48 cells caused by cetuximab by triggering the STAT3 signaling pathway. Conclusively, we conclude that HOXB8 has played an essential role in cetuximab-resistant mCRC and that treating HOXB8 specifically may be a useful treatment approach for certain cetuximab-resistant mCRC patients.

Cetuximab every 2 weeks versus standard weekly dosing administration schedule

Cetuximab every 2 weeks (Q2W) dosing schedule is approved by the US FDA and by the Japanese Pharmaceuticals and Medical Devices Agency in patients with metastatic colorectal cancer and squamous cell carcinoma of the head and neck. Phase II trials have found comparable efficacy and safety for the weekly (Q1W) and Q2W schedules, and real-world studies have shown noninferiority of the Q2W compared with the Q1W schedule. Several guidelines recommend cetuximab Q2W administration as an alternative to the Q1W dosing schedule. Cetuximab Q2W can be administered with a Q2W dose of chemotherapy, making it a more convenient option to the Q1W schedule, potentially resulting in reduced costs for administration, increased flexibility for clinical staff and improved patient adherence.

How to obtain the image-derived blood concentration from 89Zr-immuno-PET scans

BACKGROUND

PET scans using zirconium-89 labelled monoclonal antibodies (89Zr-mAbs), known as 89Zr-immuno-PET, are made to measure uptake in tumour and organ tissue. Uptake is related to the supply of 89Zr-mAbs in the blood. Measuring activity concentrations in blood, however, requires invasive blood sampling. This study aims to identify the best delineation strategy to obtain the image-derived blood concentration (IDBC) from 89Zr-immuno-PET scans.

METHODS

PET imaging and blood sampling of two 89Zr-mAbs were included, 89Zr-cetuximab and 89Zr-durvalumab. For seven patients receiving 89Zr-cetuximab, PET scans on 1-2 h, 2 and 6 days post-injection (p.i.) were analysed. Five patients received three injections of 89Zr-durvalumab. The scanning protocol for the first two injections consisted of PET scanning on 2, 5 and 7 days p.i. and for the third injection only on 7 days p.i. Blood samples were drawn with every PET scan and the sample-derived blood concentration (SDBC) was used as gold standard for the IDBC. According to an in-house developed standard operating procedure, the aortic arch, ascending aorta, descending aorta and left ventricle were delineated. Bland-Altman analyses were performed to assess the bias (mean difference) and variability (1.96 times the standard deviation of the differences) between IDBC and SDBC.

RESULTS

Overall, the activity concentration obtained from the IDBC was lower than from the SDBC. When comparing IDBC with SDBC, variability was smallest for the ascending aorta (20.3% and 17.0% for 89Zr-cetuximab and 89Zr-durvalumab, respectively). Variability for the other regions ranged between 17.9 and 30.8%. Bias for the ascending aorta was - 10.9% and - 11.4% for 89Zr-cetuximab and 89Zr-durvalumab, respectively.

CONCLUSIONS

Image-derived blood concentrations should be obtained from delineating the ascending aorta in 89Zr-immuno-PET scans, as this results in the lowest variability with respect to sample-derived blood concentrations.

Plasma Cetuximab Concentrations Correlate With Survival in Patients With Advanced KRAS Wild Type Colorectal Cancer

BACKGROUND

Cetuximab is a standard of care therapy for patients with RAS wild-type (WT) advanced colorectal cancer. Limited data suggest a wide variation in cetuximab plasma concentrations after standard dosing regimens. We correlated cetuximab plasma concentrations with survival and toxicity.

METHODS

The CO. 20 study randomized patients with RAS WT advanced colorectal cancer in a 1:1 ratio to cetuximab 400 mg/m2 intravenously followed by weekly maintenance of 250 mg/m2, plus brivanib 800 mg orally daily or placebo. Blood samples obtained at week 5 precetuximab treatment were analyzed by ELISA. Patients were grouped into tertiles based on plasma cetuximab concentrations. Cetuximab concentration tertiles were correlated with survival outcomes and toxicity. Patient demographic and biochemical parameters were evaluated as co-variables.

RESULTS

Week 5 plasma cetuximab concentrations were available for 591 patients (78.8%). The median overall survival (OS) was 11.4 months and 7.8 months for patients in the highest (T3) and lowest tertiles (T1) respectively. On multivariable analysis, plasma cetuximab concentration was associated with OS (HR 0.66, 95% confidence interval [CI]: 0.53-0.83, P < .001, T3 vs. T1), and a trend towards progression-free survival (HR 0.82, 95% CI: 0.66-1.02, P = .07, T3 vs. T1). There was no association between cetuximab concentration and skin toxicity or diarrhea.

CONCLUSION

The standard cetuximab dosing regimen may not be optimal for all patients. Further pharmacokinetic studies are needed to optimize cetuximab dosing given the potential improvement in OS.

Compliance with Therapeutic Goods Association prescribing information: weekly or second weekly cetuximab for the treatment of metastatic colorectal cancer

BACKGROUND

Treatment with cetuximab provides a survival benefit for patients with RAS wild-type metastatic colorectal cancer (mCRC). Practice-defining cetuximab studies utilised weekly (q1w) administration. More convenient second weekly (q2w) administration is supported by pharmacokinetic data and a recent meta-analysis, but large head-to-head studies have not been conducted. Therapeutic Goods Association (TGA) prescribing information states cetuximab be administered q1w for all indications.

AIM

To assess the real-world use of q1w versus q2w cetuximab schedule and any difference in outcomes.

METHODS

We analysed data from a prospective mCRC database at seven Melbourne hospitals from January 2010 to August 2019. Characteristics and outcomes for cetuximab-treated patients were examined, comparing q1w versus q2w schedules. Progression-free survival (PFS) and overall survival (OS) were the primary endpoints.

RESULTS

Of 214 eligible patients, 103 (48%) received q1w and 111 (52%) received q2w cetuximab. Q2w cetuximab has been used in >70% of patients from 2015. Q2w was more commonly used in public patients (70% vs 13% in private, P < 0.001), in left-sided primary tumours (83% vs 68%, P = 0.025) and in combination with chemotherapy (73% q2w vs 40% q1w, P < 0.001). Q2w treatment was less common in BRAFV600E mutated tumours (4% vs 13%, P = 0.001). PFS was similar across all lines of therapy, including when analyses were limited to a left-sided primary and there was no difference in OS in multivariate analysis.

CONCLUSION

This real-world analysis shows q2w cetuximab has become the dominant method of administration, despite TGA guidance. Our outcome data adds to other data supporting the use of q2w cetuximab as the standard option. Consideration could be given to modifying current TGA advice.

Real-world comparison between weekly versus biweekly dosing of cetuximab for metastatic colorectal cancer

Aim: This real-world study aims to compare overall survival (OS) associated with biweekly (Q2W) versus weekly (Q1W) cetuximab dosing regimens for metastatic colorectal cancer (mCRC) treatment in the US. Methods: Adult patients with KRAS wild-type mCRC who received cetuximab ± chemotherapy from 2013 to 2019 were selected using Flatiron Health's electronic health records database. Propensity score matching was used to balance Q2W and Q1W cohorts on baseline patient characteristics. The Kaplan-Meier method was used for survival analyses. Several sensitivity analyses were conducted to assess the robustness of findings from the main analysis. Results: Of 1075 patients in the study, 60.7% received cetuximab Q1W and 39.3% Q2W. Median OS (95% confidence interval) in months was 17.2 (15.3, 18.8) for Q2W versus 14.3 (12.8, 16.0) for Q1W; p = 0.246. Similar OS between the dosing cohorts was observed in sensitivity analyses. Conclusion: Weekly and biweekly cetuximab had comparable effectiveness in this real-world study.

Biweekly cetuximab in combination with capecitabine and oxaliplatin (XELOX) or irinotecan (XELIRI) in the first-line and second-line treatment of patients with RAS wild-type metastatic colorectal cancer

Background

Oral capecitabine in combination with intravenous oxaliplatin (XELOX) or irinotecan (XELIRI) are acceptable substitutions to fully intravenous regimens. Biweekly (as opposed to weekly) cetuximab is more convenient when combined with biweekly chemotherapy. Here, we report the tolerability and efficacy of biweekly cetuximab in combination with biweekly XELOX or XELIRI in patients with RAS wild-type metastatic colorectal cancer (RAS-WT mCRC).

Methods

Clinical data of consecutive patients with mCRC who received biweekly cetuximab (500 mg/m²) in combination with XELOX or XELIRI between January 2009 and May 2019 in the first- or second-line settings was extracted. Dosage of XEL (Capecitabine/XELODA) was 1,000 mg/m² twice daily for 9 days, plus on day 1 oxaliplatin 85 mg/m² or irinotecan 180 mg/m². Treatment dose reduction and delay for ≥7 days was analysed as surrogates for toxicity. Extended RAS testing was performed in the context of this study for patients who received treatment based on limited KRAS-WT genotype.

Results

Sixty one patients with RAS-WT mCRC fulfilled the eligibility criteria. XELOX was administered to 26 (42.6%) and XELIRI to 35 (57.4%) of patients. For all patients in the first-line setting, the objective response rate (ORR), median progression free survival (PFS) and median overall survival (OS) were 54%, 8 months and 25 months, respectively. The corresponding outcomes for the subgroup of patients who received first-line XELOX were 68%, 10 months and not reached, respectively. For all patients in the second-line setting, the ORR, PFS and OS were 50%, 7 months and 20 months, respectively. Chemotherapy components dose reduction and delays were observed in 18 (29.5%) and 25 (41%) patients, respectively. The corresponding frequencies for cetuximab were 3 (5%) and 31 (50.8%).

Conclusion

Biweekly cetuximab in combination with XELOX or XELIRI is tolerable and effective. The addition of cetuximab to capecitabine and oxaliplatin is associated with favourable outcome.

Artificial Intelligence Predictive Models of Response to Cytotoxic Chemotherapy Alone or Combined to Targeted Therapy for Metastatic Colorectal Cancer Patients: A Systematic Review and Meta-Analysis

Tailored treatments for metastatic colorectal cancer (mCRC) have not yet completely evolved due to the variety in response to drugs. Therefore, artificial intelligence has been recently used to develop prognostic and predictive models of treatment response (either activity/efficacy or toxicity) to aid in clinical decision making. In this systematic review, we have examined the ability of learning methods to predict response to chemotherapy alone or combined with targeted therapy in mCRC patients by targeting specific narrative publications in Medline up to April 2022 to identify appropriate original scientific articles. After the literature search, 26 original articles met inclusion and exclusion criteria and were included in the study. Our results show that all investigations conducted on this field have provided generally promising results in predicting the response to therapy or toxic side-effects. By a meta-analytic approach we found that the overall weighted means of the area under the receiver operating characteristic (ROC) curve (AUC) were 0.90, 95% C.I. 0.80-0.95 and 0.83, 95% C.I. 0.74-0.89 in training and validation sets, respectively, indicating a good classification performance in discriminating response vs. non-response. The calculation of overall HR indicates that learning models have strong ability to predict improved survival. Lastly, the delta-radiomics and the 74 gene signatures were able to discriminate response vs. non-response by correctly identifying up to 99% of mCRC patients who were responders and up to 100% of patients who were non-responders. Specifically, when we evaluated the predictive models with tests reaching 80% sensitivity (SE) and 90% specificity (SP), the delta radiomics showed an SE of 99% and an SP of 94% in the training set and an SE of 85% and SP of 92 in the test set, whereas for the 74 gene signatures the SE was 97.6% and the SP 100% in the training set.

Biweekly administration of cetuximab in Japanese patients with recurrent or metastatic head and neck cancer

BACKGROUND

Cetuximab (Cmab) plays an important role in the treatment for recurrent or metastatic head and neck cancer (R/M HNC). To date, however, no safety data on biweekly administration of cetuximab at a dose of 500 mg/m² (biweekly Cmab) for Japanese HNC patients have been available.

METHODS

We retrospectively reviewed the clinical records of five R/M HNC patients who received biweekly Cmab in our institute between January 2016 and September 2021 and compared the safety profile between two phases of weekly 250 mg/m² and biweekly 500 mg/m² Cmab in the identical patients.

RESULTS

All patients initially received Cmab in combination with chemotherapy. Chemotherapy consisted of paclitaxel plus carboplatin in two patients, cisplatin + 5-FU in one patient, and paclitaxel in two patients. Three patients switched treatment schedule from weekly Cmab to biweekly Cmab, while two patients received biweekly Cmab after completion of chemotherapy. The main reason for switching to biweekly Cmab was an unacceptably long commuting time to the hospital. The median duration of Cmab was 217 days (49-321) during weekly Cmab with or without chemotherapy and 42 days (28-175) during biweekly Cmab. Median dose of biweekly Cmab was 4 (3-12). During biweekly Cmab, worsened (Grade ≥ 2) toxicities were observed in two patients: one with grade 2 dry skin and the second with grade 2 skin infection. None developed grade ≥ 3 adverse events or discontinued treatment due to Cmab-related adverse events.

CONCLUSION

Biweekly Cmab was well tolerated and did not demonstrate severe toxicities related to Cmab for R/M HNC.

Efficacy and Safety of Cetuximab Dosing (biweekly vs weekly) in Patients with KRAS Wild-type Metastatic Colorectal Cancer: A Meta-analysis

BACKGROUND

Cetuximab 500 mg/m2 biweekly (Q2W) plus chemotherapy is commonly used and recommended by NCCN guidelines. This meta-analysis compares efficacy and safety between Q2W versus weekly (Q1W) cetuximab dosing.

METHODS

A systematic literature review was performed on Pubmed and RightFind (2007-2017) for patients with KRAS wild-type mCRC who received Q2W or Q1W cetuximab and other treatments. Observational studies and case reports were excluded. Randomized trials comparing Q2W and Q1W dosing, and single-arm trials with only Q2W schedule were included. CRYSTAL, a phase 3 randomized study with Q1W cetuximab dosing was paired with each single-arm study with a Q2W schedule and reweighted to achieve similar demographic/baseline characteristics. Overall survival (OS) and progression-free survival (PFS) with hazard ratios (HR), overall response rate (ORR) with odds ratios, and risk difference of adverse events of special interest (AESI) between Q2W versus Q1W cetuximab were analyzed.

RESULTS

Five phase 2 studies with cetuximab Q2W/Q1W dosing schedules were identified: CECOG (phase 2; Q2W, n = 77; Q1W, n = 75), NORDIC 7.5 (phase 2; Q2W, n = 152) and NORDIC 7 (arm C of phase 3; Q1W, n = 109), CELINE (n = 60), OPTIMIX (n = 99), and APEC (n = 289) all phase 2, Q2W, single-arm studies paired with CRYSTAL Q1W dosing (n = 303). Efficacy was similar between Q2W versus Q1W administration; OS HR = 0.96, 95% confidence interval (CI) [0.89, 1.04]; PFS HR = 0.96, 95% CI [0.87, 1.05]; ORR odds ratio 1.16, 95% CI [0.96, 1.41]. Mean differences (Q2W-Q1W) across AESI rates were not clinically meaningful with no obvious directionality.

CONCLUSION

This meta-analysis demonstrated no significant differences in efficacy and safety between Q2W versus Q1W cetuximab administration in mCRC patients.

A phospho-proteomic study of cetuximab resistance in KRAS/NRAS/BRAFV600 wild-type colorectal cancer

PURPOSE

We hypothesised that plasticity in signal transduction may be a mechanism of drug resistance and tested this hypothesis in the setting of cetuximab resistance in patients with KRAS/NRAS/BRAFV600 wild-type colorectal cancer (CRC).

METHODS

A multiplex antibody-based platform was used to study simultaneous changes in signal transduction of 55 phospho-proteins in 12 KRAS/NRAS/BRAFV600 wild-type CRC cell lines (6 cetuximab sensitive versus 6 cetuximab resistant) following 1 and 4 h in vitro cetuximab exposure. We validated our results in CRC patient samples (n = 4) using ex vivo exposure to cetuximab in KRAS/NRAS/BRAFV600 cells that were immunomagnetically separated from the serous effusions of patients with known cetuximab resistance.

RESULTS

Differences in levels of phospho-proteins in cetuximab sensitive and resistant cell lines included reductions in phospho-RPS6 and phospho-PRAS40 in cetuximab sensitive, but not cetuximab resistant cell lines at 1 and 4 h, respectively. In addition, phospho-AKT levels were found to be elevated in 3/4 patient samples following ex vivo incubation with cetuximab for 1 h. We further explored these findings by studying the effects of combinations of cetuximab and two PI3K pathway inhibitors in 3 cetuximab resistant cell lines. The addition of PI3K pathway inhibitors to cetuximab led to a significantly higher reduction in colony formation capacity compared to cetuximab alone.

CONCLUSION

Our findings suggest activation of the PI3K pathway as a mechanism of cetuximab resistance in KRAS/NRAS/BRAFV600 wild-type CRC.

Conventional transarterial chemoembolization combined with systemic therapy versus systemic therapy alone as second-line treatment for unresectable colorectal liver metastases: randomized clinical trial

BACKGROUND

The combination of conventional transarterial chemoembolization (cTACE) and systemic therapy has the potential to treat chemotherapy-refractory unresectable colorectal liver metastases (CRLMs). This study aimed to compare survival after this combined treatment versus systemic chemotherapy alone.

METHODS

This single-centre RCT included patients with unresectable CRLMs that progressed after first-line treatment. Patients were randomized on a 1 : 1 basis to either systemic chemotherapy with or without cTACE, without further stratification. The primary outcome was progression-free survival (PFS). Secondary outcomes were overall response rate, disease control rate, conversion rate to liver resection, overall survival, and adverse events.

RESULTS

Of 180 patients recruited, 168 were randomized. Eighty-five patients in arm A received systemic chemotherapy plus cTACE and 83 in arm B received systemic chemotherapy alone. Median PFS was longer in arm A than B (6.7 versus 3.8 months; hazard ratio (HR) 0.67, 95 per cent c.i. 0.49 to 0.91; P = 0.009), but did not translate into prolonged median overall survival (18.4 versus 14.8 months; HR = 0.92, 0.62 to 1.36; P = 0.669). Overall response rates (20 versus 22 per cent; P = 0.788) and conversion rate to liver resection (18 versus 16 per cent; P = 0.730) were no different between arms A and B. The disease control rate was higher in arm A than arm B (67 versus 51 per cent; P = 0.030). No adverse event higher than grade 3 according to the Common Terminology Criteria for Adverse Events was observed during treatment.

CONCLUSION

Systemic chemotherapy plus cTACE is a safe option as second-line treatment for unresectable colorectal liver metastases, with a modest effect on PFS. Registration number: NCT03783559 (http://www.clinicaltrials.gov).

Cetuximab plus irinotecan administered biweekly with reduced infusion time to heavily pretreated patients with metastatic colorectal cancer and related RAS and BRAF mutation status

Metastatic colorectal cancer (mCRC) is treated with cetuximab 250 mg/m2 administered weekly over 1 hour or biweekly (q2w) over 3.5 hours when combined with irinotecan. This prospective study investigated cetuximab 500 mg/m2 plus irinotecan 180 mg/m2 administered q2w over 1.5 hours independent of RAS or BRAF mutation status in mCRC patients in a third-line setting. The intention-to-treat population included 181 patients. No patients had complete response, 18% had partial responses (PR) and 48% stable disease (SD). For cetuximab, a relative dose intensity of ≥90% was reached in 78% and for irinotecan in 67% of the patients. Grade 3 to 4 toxicities were pain (17%), fatigue (9%), neutropenia (8%), diarrhea (8%), rash (8%), infection (7%) and hypersensitivity (3%). No deaths occurred. Next-generation sequencing in 96.7% of the patients revealed that 50.3% had RAS and BRAFV600E wild type (WT), with a mutation type (MT) in 45.1% of the RAS and 4.4% of the BRAFV600E genes. In patients with RAS-WT and RAS-MT tumors, a PR was obtained in 32% and 4% (P = .000003) and an SD in 43% and 53%, respectively, with a superior PFS (6.2 vs 3.7 months; hazard ratio [HR] 2.12, P = .00001) and OS (12.9 vs 8.8 months; HR 1.71, P = .0008). Treatment efficacy was poor in 7.4% of patients with an RAS mutation outside KRAS exon 2 and in 38% of patients with KRAS exon 2 mutations. Administration of cetuximab and irinotecan q2w, shortening treatment time from 3.5 to 1.5 hours, is recommended as standard therapy.

Cost-minimization analysis of biweekly dosing of cetuximab and FOLFIRI compared with panitumumab and FOLFOX for first-line treatment of patients with KRAS wild-type metastatic colorectal cancer in the United States

AIM

To compare the cost of biweekly regimens of first-line (1L) treatments of cetuximab-folinic acid, fluorouracil, and irinotecan (FOLFIRI) versus panitumumab-folinic acid, fluorouracil, and oxaliplatin (FOLFOX) in patients with Kirsten's rat sarcoma wild type (KRAS WT) metastatic colorectal cancer (mCRC) in the United States, across varying weights and body surface areas (BSAs).

MATERIALS AND METHODS

Cost-minimization analysis (CMA) was performed to estimate per-patient cost differences of cetuximab-FOLFIRI versus panitumumab-FOLFOX. The CMA estimated the costs of RAS testing, premedication, drug acquisition, treating infusion reactions (IRs), supportive therapy, and biweekly administration of chemotherapy, cetuximab (500 mg/m²), and panitumumab (6 mg/kg) over 43 weeks (median progression-free survival). To calculate dose and cost, weight and height data were gathered from an electronic health record-derived de-identified database (n = 7,669; January 2013-October 2020). Base case analysis utilized mean weight/BSA of the overall cohort (82.04 kg/1.92 m²), and alternate scenarios were based on 88.18 kg/2.03 m² (men, n = 4,477) and 73.43 kg/1.76 m² (women, n = 3,192).

RESULTS

For the base case, total treatment costs were $167,853 for cetuximab-FOLFIRI and $168,254 for panitumumab-FOLFOX; cost savings per patient receiving cetuximab-FOLFIRI was $400. Cost savings in alternate scenarios (men, $15,138; women, $15,004) resulted from lower drug acquisition costs for cetuximab (men, $14,833; women $14,854) and administration cost ($440) versus panitumumab. Cost savings of cetuximab-FOLFIRI in treating IR ($353) were similar across all scenarios.

LIMITATIONS

With no head-to-head clinical trial data in the 1L setting, assumptions of similarity in efficacy and safety of cetuximab versus panitumumab were based on published network meta-analysis and the ASPECCT trial. This model did not consider a lifetime horizon. Costs of managing all adverse events (except IR) were not included.

CONCLUSIONS

Biweekly cetuximab-FOLFIRI offers cost savings compared with panitumumab-FOLFOX for 1L therapy of patients with KRAS WT mCRC in the United States. These cost differences were observed for the overall population and across different BSA and weights for men and women.

Comparison of Various Phase I Combination Therapy Designs in Oncology for Evaluation of Early Tumor Shrinkage Using Simulations

There is still a lack of efficient designs for identifying the dose response in oncology combination therapies in early clinical trials. The concentration response relationship can be identified using the early tumor shrinkage time course, which has been shown to be a good early response marker of clinical efficacy. The performance of various designs using an exposure–tumor growth inhibition model was explored using simulations. Different combination effects of new drug M and cetuximab (reference therapy) were explored first assuming no effect of M on cetuximab (to investigate the type I error (α)), and subsequently assuming additivity or synergy between cetuximab and M. One‐arm, two‐arm, and four‐arm designs were evaluated. In the one‐arm design, 60 patients received cetuximab + M. In the two‐arm design, 30 patients received cetuximab and 30 received cetuximab + M. In the four‐arm design, in addition to cetuximab and cetuximab + M as standard doses, combination arms with lower doses of cetuximab were evaluated (15 patients/arm). Model‐based predictions or “simulated observations” of early tumor shrinkage at week 8 (ETS8) were compared between the different arms. With the same number of individuals, the one‐arm design showed better statistical power than other designs but led to strong inflation of α in case of misestimated reference for ETS8 value. The two‐arm design protected against this misestimation and, with the same total number of subjects, would provide higher statistical power than a four‐arm design. However, a four‐arm design would be helpful for exploring more doses of cetuximab in combination with M to better understand the interaction.

Semimechanistic Clearance Models of Oncology Biotherapeutics and Impact of Study Design: Cetuximab as a Case Study

This study aimed to explore the currently competing and new semimechanistic clearance models for monoclonal antibodies and the impact of clearance model misspecification on exposure metrics under different study designs exemplified for cetuximab. Six clearance models were investigated under four different study designs (sampling density and single/multiple‐dose levels) using a rich data set from two cetuximab clinical trials (226 patients with metastatic colorectal cancer) and using the nonlinear mixed‐effects modeling approach. A two‐compartment model with parallel Michaelis–Menten and time‐decreasing linear clearance adequately described the data, the latter being related to post‐treatment response. With respect to bias in exposure metrics, the simplified time‐varying linear clearance (CL) model was the best alternative. Time‐variance of the linear CL component should be considered for biotherapeutics if response impacts pharmacokinetics. Rich sampling at steady‐state was crucial for unbiased estimation of Michaelis–Menten elimination in case of the reference (parallel Michaelis–Menten and time‐varying linear CL) model.

Phase I Study of Ficlatuzumab and Cetuximab in Cetuximab-Resistant, Recurrent/Metastatic Head and Neck Cancer

Cetuximab, an anti-EGFR monoclonal antibody (mAb), is approved for advanced head and neck squamous cell carcinoma (HNSCC) but benefits a minority. An established tumor-intrinsic resistance mechanism is cross-talk between the EGFR and hepatocyte growth factor (HGF)/cMet pathways. Dual pathway inhibition may overcome cetuximab resistance. This Phase I study evaluated the combination of cetuximab and ficlatuzumab, an anti-HGF mAb, in patients with recurrent/metastatic HNSCC. The primary objective was to establish the recommended Phase II dose (RP2D). Secondary objectives included overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). Mechanistic tumor-intrinsic and immune biomarkers were explored. Thirteen patients enrolled with no dose-limiting toxicities observed at any dose tier. Three evaluable patients were treated at Tier 1 and nine at Tier 2, which was determined to be the RP2D (cetuximab 500 mg/m² and ficlatuzumab 20 mg/kg every 2 weeks). Median PFS and OS were 5.4 (90% CI = 1.9–11.4) and 8.9 (90% CI = 2.7–15.2) months, respectively, with a confirmed ORR of 2 of 12 (17%; 90% CI = 6–40%). High circulating soluble cMet levels correlated with poor survival. An increase in peripheral T cells, particularly the CD8⁺ subset, was associated with treatment response whereas progression was associated with expansion of a distinct myeloid population. This well-tolerated combination demonstrated promising activity in cetuximab-resistant, advanced HNSCC.

Treatment of inoperable elderly head and neck cancer patients

PURPOSE OF REVIEW

Elderly head and neck cancer (HNC) patients are very rarely enrolled in clinical trials, and even more so in dedicated trials in curative or palliative setting. As a result, no standards of treatment exist for this population and thus, adaptation of standard treatments is commonly used.

RECENT FINDINGS

The choice between a monotherapy and a platinum-cetuximab combination is based on the performance status, which is not suitable and/or sufficient to evaluate the patient ability to receive a systemic treatment combined or not with radiotherapy. The evaluation of functional age using geriatric assessment is recommended. However, access to comprehensive geriatric assessment is limited in many centers, and the choice of the type of treatment is often not based on objective and reproducible criteria. As a result, fragile elderly HNC patients may be overtreated with a risk of increased toxicity and fit patients proposed for suboptimal treatment with a risk of failure of tumor control.

SUMMARY

It is therefore crucial to develop and evaluate customized treatments by enrolling elderly HNC patients in dedicated therapeutics trials, such as the ELAN (Elderly Head and Neck Cancer) studies or new approaches involving promising immunotherapies. To administer the most suitable therapy, a simple and reproducible geriatric assessment could efficiently guide practitioners.

Machine Learning Analysis of Individual Tumor Lesions in Four Metastatic Colorectal Cancer Clinical Studies: Linking Tumor Heterogeneity to Overall Survival

Total tumor size (TS) metrics used in TS models in oncology do not consider tumor heterogeneity, which could help to better predict drug efficacy. We analyzed individual target lesions (iTLs) of patients with metastatic colorectal carcinoma (mCRC) to determine differences in TS dynamics by using the ClassIfication Clustering of Individual Lesions (CICIL) methodology. Results from subgroup analyses comparing genetic mutations and TS metrics were assessed and applied to survival analyses. Data from four mCRC clinical studies were analyzed (1781 patients, 6369 iTLs). CICIL was used to assess differences in lesion TS dynamics within a tissue (intra-class) or across different tissues (inter-class). First, lesions were automatically classified based on their location. Cross-correlation coefficients (CCs) determined if each pair of lesions followed similar or opposite dynamics. Finally, CCs were grouped by using the K-means clustering method. Heterogeneity in tumor dynamics was lower in the intra-class analysis than in the inter-class analysis for patients receiving cetuximab. More tumor heterogeneity was found in KRAS mutated patients compared to KRAS wild-type (KRASwt) patients and when using sum of longest diameters versus sum of products of diameters. Tumor heterogeneity quantified as the median patient's CC was found to be a predictor of overall survival (OS) (HR = 1.44, 95% CI 1.08-1.92), especially in KRASwt patients. Intra- and inter-tumor tissue heterogeneities were assessed with CICIL. Derived metrics of heterogeneity were found to be a predictor of OS time. Considering differences between lesions' TS dynamics could improve oncology models in favor of a better prediction of OS.

[89Zr]Zr-cetuximab PET/CT as biomarker for cetuximab monotherapy in patients with RAS wild-type advanced colorectal cancer

PURPOSE

One-third of patients with RAS wild-type mCRC do not benefit from anti-EGFR monoclonal antibodies. This might be a result of variable pharmacokinetics and insufficient tumor targeting. We evaluated cetuximab tumor accumulation on [⁸⁹Zr]Zr-cetuximab PET/CT as a potential predictive biomarker and determinant for an escalating dosing strategy.

PATIENTS AND METHODS

PET/CT imaging of [⁸⁹Zr]Zr-cetuximab (37 MBq/10 mg) after a therapeutic pre-dose (500 mg/m² ≤ 2 h) cetuximab was performed at the start of treatment. Patients without visual tumor uptake underwent dose escalation and a subsequent [⁸⁹Zr]Zr-cetuximab PET/CT. Treatment benefit was defined as stable disease or response on CT scan evaluation after 8 weeks.

RESULTS

Visual tumor uptake on [⁸⁹Zr]Zr-cetuximab PET/CT was observed in 66% of 35 patients. There was no relationship between PET positivity and treatment benefit (52% versus 80% for PET-negative, P = 0.16), progression-free survival (3.6 versus 5.7 months, P = 0.15), or overall survival (7.1 versus 9.4 months, P = 0.29). However, in 67% of PET-negative patients, cetuximab dose escalation (750-1250 mg/m²) was applied, potentially influencing outcome in this group. None of the second [⁸⁹Zr]Zr-cetuximab PET/CT was positive. Eighty percent of patients without visual tumor uptake had treatment benefit, making [⁸⁹Zr]Zr-cetuximab PET/CT unsuitable as a predictive biomarker. Tumor SUV_peak did not correlate to changes in tumor size on CT (P = 0.23), treatment benefit, nor progression-free survival. Cetuximab pharmacokinetics were not related to treatment benefit. BRAF mutations, right-sidedness, and low sEGFR were correlated with intrinsic resistance to cetuximab.

CONCLUSION

Tumor uptake on [⁸⁹Zr]Zr-cetuximab PET/CT failed to predict treatment benefit in patients with RAS wild-type mCRC receiving cetuximab monotherapy. BRAF mutations, right-sidedness, and low sEGFR correlated with intrinsic resistance to cetuximab.

Efficacy and safety of anti-EGFR monoclonal antibodies combined with different chemotherapy regimens in patients with RAS wild-type metastatic colorectal cancer: A meta-analysis

OBJECTIVES

To investigate the efficacy and safety of adding anti-epidermal growth factor receptor [EGFR] MoAbs to various chemotherapy regimens in patients with RAS wild-type metastasized colorectal cancer (RAS WT metastatic colorectal cancer [mCRC]) and to identify the optimal combination regimens.

METHODS

We searched MEDLINE, EMBASE, and CENTRAL from the inception date to 20th May 2019. Randomized clinical trials investigating chemotherapy with or without anti-EGFR MoAbs in treatment of patients with RAS WT mCRC were included.

RESULTS

Eighteen studies involving 8848 participants were eligible. Comparing with oxaliplatin-based chemotherapy, adding anti-EGFR MoAbs benefited only in progression-free survival (PFS) (hazard ratio [HR] = 0.80, 95% confidence interval [CI]: 0.67 to 0.94), but not in overall survival (OS) (HR = 0.89, 95% CI: 0.78 to 1.02). Further sensitivity analysis indicated that adding anti-EGFR MoAbs to FOLFOLX regimen as a first-line treatment showed benefits in both PFS and OS (PFS: HR = 0.74, 95% CI: 0.64 to 0.84; OS: HR = 0.83, 95% CI: 0.73 to 0.95, respectively). Comparing with irinotecan-based chemotherapy or best supportive care, adding anti-EGFR MoAbs revealed an improvement in both PFS (HR = 0.77, 95% CI: 0.69 to 0.86; HR = 0.46, 95% CI: 0.40 to 0.54, respectively) and OS (HR = 0.89, 95% CI: 0.80 to 0.98; HR = 0.65, 95% CI: 0.54 to 0.78, respectively).

CONCLUSION

Anti-EGFR MoAbs as a monotherapy or in combination with either irinotecan-based chemotherapy or FOLFOX in patients with RAS wild-type mCRC have better response and survival outcome, whereas OS does not benefit from adding anti-EGFR MoAbs to another oxaliplatin-based regimen. Anti-EGFR MoAbs have increased the risk of adverse effects than chemotherapy alone. More high-quality randomized controlled trials for RAS wild type are necessary.

Distinguishing Features of Cetuximab and Panitumumab in Colorectal Cancer and Other Solid Tumors

Cetuximab and panitumumab are two distinct monoclonal antibodies (mAbs) targeting the epidermal growth factor receptor (EGFR), and both are widely used in combination with chemotherapy or as monotherapy to treat patients with RAS wild-type metastatic colorectal cancer. Although often considered interchangeable, the two antibodies have different molecular structures and can behave differently in clinically relevant ways. More specifically, as an immunoglobulin (Ig) G1 isotype mAb, cetuximab can elicit immune functions such as antibody-dependent cell-mediated cytotoxicity involving natural killer cells, T-cell recruitment to the tumor, and T-cell priming via dendritic cell maturation. Panitumumab, an IgG2 isotype mAb, does not possess these immune functions. Furthermore, the two antibodies have different binding sites on the EGFR, as evidenced by mutations on the extracellular domain that can confer resistance to one of the two therapeutics or to both. We consider a comparison of the properties of these two antibodies to represent a gap in the literature. We therefore compiled a detailed, evidence-based educational review of the known molecular, clinical, and functional differences between the two antibodies and concluded that they are distinct therapeutic agents that should be considered individually during treatment planning. Available data for one agent can only partly be extrapolated to the other. Looking to the future, the known immune activity of cetuximab may provide a rationale for this antibody as a combination partner with investigational chemotherapy plus immunotherapy regimens for colorectal cancer.

Budget impact of bimonthly use of cetuximab in patients diagnosed with metastatic colorectal cancer

Aim: Cetuximab is used for the treatment of RAS wild-type metastatic colorectal cancer patients. Standard administration schedule is once a week; however, the bioequivalence of an every-other-week (EOW) schedule was demonstrated. Methods: We compared a base case scenario of 100% weekly administration to an EOW at 50 or 100%. Medical examinations, patient management and loss of productivity were considered. Results: Base case was estimated at €100.6 million versus €92.8 million and €84.9 million of EOW 50 and 100%, which showed a cost reduction of 8 and 16%, respectively. Indirect costs accounted for 65% in both scenarios. Conclusion: The adoption of an EOW administration schedule of cetuximab reduced direct and indirect costs substantially.

Biweekly cetuximab in combination with platinum and 5-fluorouracil in metastatic head and neck carcinoma

Background and Aim

The combination of cetuximab with platinum and 5-fluorouracil (5-FU) chemotherapy prolongs survival in patients with metastatic or recurrent squamous-cell carcinoma of the head and neck (SCCHN). Biweekly (once in 2 weeks) administration of cetuximab requires fewer hospital visits and decreases treatment costs; therefore, it is more convenient both for the patients and for the healthcare providers. Here, we assessed the efficacy, safety, and tolerability of an alternative biweekly regimen of cetuximab in combination with platinum and 5-FU chemotherapy as a first-line treatment for these patients.

Methods and Materials

Medical records of patients with metastatic or recurrent non-nasopharyngeal SCCHN who were treated with a biweekly regimen of cetuximab (500 mg/m² on day 1), cisplatin (40 mg/m² on day 1) or carboplatin (target area under the curve 3.5 mg/ml × min on day 1), folinic acid (400 mg/m² on day 1), and 5-FU (400 mg/m² bolus on day 1 followed by continuous infusion of 2,400 mg/m² 5-FU over 46 h) were retrospectively reviewed. Survival estimates were calculated with the Kaplan-Meier method.

Results

In total, 60 patients were included. The median age of the patients was 60.5. The objective response rate was 53.3% (95% confidence interval [CI] = 40.7-65.9). The median progression-free survival duration was 6.8 months (95% CI = 5.5-8.1) and the median overall survival duration was 13.3 months (95% CI = 8.4-18.2). The most common grade 3 or 4 adverse events were neutropenia (28.3%) and leucopenia (13.3%). Grade 3 or 4 rash was observed in 3.3% of the patients.

Conclusion

Biweekly administration of cetuximab, cisplatin, and 5-FU is an effective regimen with a favorable toxicity profile for the first-line treatment of metastatic or recurrent SCCHN. These results warrant further evaluation of this regimen in prospective trials.

Rationale and budget impact of bimonthly use of Cetuximab in patients with recurrent and/or metastatic head and neck cancer

BACKGROUND

In recurrent and/or metastatic head and neck squamous cell cancer, Cetuximab is administered once a week, followed by weekly doses. We present the clinical rationale of a different schedule of maintenance Cetuximab and we estimate the potential economic benefits on the health care budget from a societal perspective in Italy.

METHODS

A budget impact (BI) excel-based model was developed comparing a base case scenario of 100% weekly administration with a dose of 250 mg/m² to an every-other-week (EOW) administration at 50% or 100% with a dose of 500 mg/m² .

RESULTS

In the EOW, 50% scenario it was calculated a cost reduction of €347 000 of which 70% attributable to indirect costs, increasing to €694 000 after 4 months.

CONCLUSIONS

In our analysis, we showed that this simplified schedule could also reduce the costs of treatments both for the health system (direct costs) and for the society (indirect costs).

Transcriptional subtyping and CD8 immunohistochemistry identifies poor prognosis stage II/III colorectal cancer patients who benefit from adjuvant chemotherapy

Purpose

Transcriptomic profiling of colorectal cancer (CRC) has led to the identification of four consensus molecular subtypes (CMS1 to 4) that have prognostic value in stage II and III disease. More recently, the Colorectal Cancer Intrinsic Subtypes (CRIS) classification system has helped to define the biology specific to the epithelial component of colorectal tumors; however, the clinical value of these classification systems in the prediction of response to standard-of-care adjuvant chemotherapy remains unknown.

Patients and Methods

Using samples from four European sites, we assembled a novel cohort of patients with stage II and III CRC (n = 156 samples) and performed transcriptomic profiling and targeted sequencing and generated a tissue microarray to enable integrated multiomics analyses. We also accessed data from two published cohorts of patients with stage II and III CRC: GSE39582 and GSE14333 (n = 479 and n = 185 samples, respectively).

Results

The epithelial-rich CMS2 subtype of CRC benefitted significantly from treatment with adjuvant chemotherapy in both stage II and III disease (P = .02 and P < .001, respectively), whereas the CMS3 subtype significantly benefitted in stage III only (P = .001). After CRIS substratification of CMS2, we observed that only the CRIS-C subtype significantly benefitted from treatment with adjuvant chemotherapy in stage II and III disease (P = .0081 and P < .001, respectively), whereas the CRIS-D subtype significantly benefitted in stage III only (P = .0034). We also observed that CRIS-C patients with low levels of CD8⁺ tumor-infiltrating lymphocytes were most at risk for relapse in both stage II and III disease (log-rank P = .0031; hazard ratio, 12.18 [95% CI, 1.51 to 98.58]).

Conclusion

Patient stratification using a combination of transcriptional subtyping and CD8 immunohistochemistry analyses is capable of identifying patients with poor prognostic stage II and III disease who benefit from adjuvant standard-of-care chemotherapy. These findings are particularly relevant for patients with stage II disease, where the overall benefit of adjuvant chemotherapy is marginal.

Innovative therapy, monoclonal antibodies, and beyond: Highlights from the eighth annual meeting

The eighth annual conference of "Innovative therapy, monoclonal antibodies, and beyond" was held in Milan on Jan. 26, 2018, and hosted by Fondazione IRCCS-Istituto Nazionale dei Tumori (Fondazione IRCCS INT). The conference was divided into two main scientific sessions, of i) pre-clinical assays and novel biotargets, and ii) clinical translation, as well as a third session of presentations from young investigators, which focused on recent achievements within Fondazione IRCCS INT on immunotherapy and targeted therapies. Presentations in the first session addressed the issue of cancer immunotherapy activity with respect to tumor heterogeneity, with key topics addressing: 1) tumor heterogeneity and targeted therapy, with the definition of the evolutionary Index as an indicator of tumor heterogeneity in both space and time; 2) the analysis of cancer evolution, with the introduction of the TRACERx Consortium-a multi-million pound UK research project focused on non-small cell lung cancer (NSCLC); 3) the use of anti-estrogen agents to boost immune recognition of breast cancer cells; and 4) the high degree of functional plasticity within the NK cell repertoire, including the expansion of adaptive NK cells following viral challenges. The second session addressed: 1) the effectiveness of radiotherapy to enhance the proportion of patients responsive to immune-checkpoint blockers (ICBs); 2) the use of MDSC scores in selecting melanoma patients with high probability to be responsive to ICBs; and 3) the relevance of the gut microbiome as a predictive factor, and the potential of its perturbation in increasing the immune response rate to ICBs. Overall, a picture emerged of tumor heterogeneity as the main limitation that impairs the effectiveness of anti-cancer therapies. Thus, the choice of a specific therapy based on reproducible and selective predictive biomarkers is an urgent unmet clinical need that should be addressed in order to increase the proportion of long-term responding patients and to improve the sustainability of novel drugs.

Potential Influence of Endothelial Adsorption on the Delayed Time to Maximum Concentration of Biopharmaceuticals

Background and objectives

Maximum plasma concentration of biopharmaceuticals sometimes occurs long after completion of intravenous infusion. The objective of this research was to study the hypothetical adsorption of biopharmaceuticals to endothelium and infusion material, which may theoretically explain this phenomenon.

Methods

Infusion procedures were mimicked in an artificial vessel covered with a confluent monolayer of endothelial cells. Three monoclonal antibodies (MAbs) and C1 inhibitor were studied.

Results

Adsorption of MAbs to endothelium was observed followed by release when the vessel was subsequently perfused with buffer. Adsorption to infusion material also occurred to various degrees and in a seemingly random fashion, with a loss of up to 15% during a single flush of the line, but release from the line was not seen.

Conclusions

Our results indicate that adsorption of biopharmaceuticals to endothelium can occur. This observation can explain the increase in plasma concentration after completion of intravenous administration.

Phase II trial of biweekly cetuximab and irinotecan as third-line therapy for pretreated KRAS exon 2 wild-type colorectal cancer

Efficacy and safety of biweekly cetuximab plus irinotecan were evaluated to provide guidance for its use in Japan as third-line treatment for pretreated metastatic colorectal cancer (mCRC) patients harboring wild-type KRAS exon 2. Objective response rate (ORR) was used as primary endpoint based on an expected proportion of 0.23 with confidence width of 0.298 (95% CI, 0.105-0.403), which showed 35 to be the minimal participant number. Forty patients, refractory to first- and second-line chemotherapy containing irinotecan, oxaliplatin, and fluoropyrimidine, were enrolled. ORR and disease control rate were 25.0% (95% CI: 11.5-38.4) and 72.5% (95% CI: 56.8-86.4), respectively. Median progression-free survival (PFS), overall survival (OS), and number of courses were 5.70 months (95% CI: 2.7-7.9), 15.1 months (95% CI: 11.8-19.0), and 10.5 (range: 3.0-31.0), respectively. Grade 3 adverse events were skin toxicity (12.5%), diarrhea (10.0%), neutropenia (5.0%), febrile neutropenia (5.0%), nausea (5.0%), anorexia (5.0%), and fatigue (2.5%). C_max mean was 723.2 μg/mL after first dose. High area under the curve (AUC)_last variance was associated with t_1/2 range of 131.2-1209.6 hours (median, 174.4 hours). Early tumor shrinkage (ETS) and median depth of response were 25.0% and 13.0%, respectively. Mutation frequencies in KRAS exon 3 or 4, NRAS, BRAF, and PIK3CA were 5.5%, 2.7%, 8.3%, and 5.5%, respectively. Multivariate Cox regression analysis assessed whether any gene mutations and ETS are predictors for PFS, and whether performance status, synchronous metastasis, and ETS are predictors for OS. Importantly, the data provide guidance for a biweekly cetuximab plus irinotecan regimen in mCRC patients.

Strategies for clinical development of monoclonal antibodies beyond first-in-human trials: tested doses and rationale for dose selection

BACKGROUND

Our previous survey on first-in-human trials (FIHT) of monoclonal antibodies (mAbs) showed that, due to their limited toxicity, the recommended phase II dose (RP2D) was only tentatively defined.

METHODS

We identified, by MEDLINE search, articles on single-agent trials of mAbs with an FIHT included in our previous survey. For each mAb, we examined tested dose(s) and dose selection rationale in non-FIHTs (NFIHTs). We also assessed the correlation between doses tested in the registration trials (RTs) of all FDA-approved mAbs and the corresponding FIHT results.

RESULTS

In the 37 dose-escalation NFIHTs, the RP2D indication was still poorly defined. In phase II-III NFIHTs (n=103 on 37 mAbs), the FIHT RP2D was the only dose tested for five mAbs. For 16 mAbs, only doses different from the FIHT RP2D or the maximum administered dose (MAD) were tested and the dose selection rationale infrequently indicated. In the 60 RTs on 27 FDA-approved mAbs with available FIHT, the FIHT RP2D was tested only for two mAbs, and RT doses were much lower than the FIHT MAD.

CONCLUSIONS

The rationale beyond dose selection in phase II and III trials of mAbs is often unclear in published articles and not based on FIHT data.

Cetuximab Pharmacokinetics Influences Overall Survival in Patients With Head and Neck Cancer

BACKGROUND

A retrospective study was conducted to analyze interindividual variability of cetuximab pharmacokinetics and its influence on survival (progression-free survival and overall survival [OS]) in a cohort of head and neck squamous cell carcinoma (HNSCC).

METHODS

Thirty-four patients received cetuximab as an infusion loading dose of 400 mg/m followed by weekly infusions of 250 mg/m. Twenty-one patients had locally advanced HNSCC, and 13 had metastatic/recurrent HNSCC. Cetuximab concentrations were measured by the enzyme-linked immunosorbent assay, and its pharmacokinetics was analyzed by a population approach. Survivals were analyzed with the log-rank test.

RESULTS

Cetuximab pharmacokinetics was best described using a 2-compartment model with both first-order and saturable (zero-order) eliminations. Estimated pharmacokinetic parameters (%CV) were central volume of distribution V1 = 3.18 L (6%), peripheral volume of distribution V2 = 5.4 L (42%), elimination clearance CL = 0.57 L/d (31%), distribution clearance Q = 0.64 L/d, and zero-order elimination rate k0 = 6.72 mg/d (29%). Both V1 and V2 increased with the body surface area. Adjunction of chemotherapy reduced CL and increased k0. OS was inversely related with cetuximab global clearance (P = 0.007) and was higher in patients with severe radiation dermatitis (P = 0.005).

CONCLUSIONS

Cetuximab pharmacokinetics in patients with HNSCC can be described using a 2-compartment model combining linear and nonlinear mechanisms of elimination. OS is associated with both cetuximab global clearance and severe radiation dermatitis.

Exposure-response relationship of ramucirumab in patients with advanced second-line colorectal cancer: exploratory analysis of the RAISE trial

PURPOSE

To characterize ramucirumab exposure-response relationships for efficacy and safety in patients with metastatic colorectal cancer (mCRC) using data from the RAISE study.

METHODS

Sparse pharmacokinetic samples were collected; a population pharmacokinetic analysis was conducted. Univariate and multivariate Cox proportional hazards models analyzed the relationship between predicted ramucirumab minimum trough concentration at steady state (C min,ss) and survival. Kaplan-Meier analysis was used to evaluate survival from patients in the ramucirumab plus folinic acid, 5-fluorouracil, and irinotecan (FOLFIRI) treatment arm stratified by C min,ss quartiles (Q). An ordered categorical model analyzed the relationship between C min,ss and safety outcomes.

RESULTS

Pharmacokinetic samples from 906 patients were included in exposure-efficacy analyses; samples from 905 patients were included in exposure-safety analyses. A significant association was identified between C min,ss and overall survival (OS) and progression-free survival (PFS) (p < 0.0001 for both). This association remained significant after adjusting for baseline factors associated with OS or PFS (p < 0.0001 for both). Median OS was 11.5, 12.9, 16.4, and 16.7, and 12.4 months for ramucirumab C min,ss Q1, Q2, Q3, Q4, and placebo group, respectively. Median PFS was 5.4, 4.6, 6.8, 8.5, and 5.2 months for ramucirumab C min,ss Q1, Q2, Q3, Q4, and placebo group, respectively. The risk of Grade ≥3 neutropenia was associated with an increase in ramucirumab exposure.

CONCLUSIONS

Exploratory exposure-response analyses suggested a positive relationship between efficacy and ramucirumab exposure with manageable toxicities in patients from the RAISE study with mCRC over the ranges of exposures achieved by a dose of 8 mg/kg every 2 weeks in combination with FOLFIRI.

Anti-EGFR monoclonal antibody panitumumab for the treatment of patients with metastatic colorectal cancer: an overview of current practice and future perspectives

INTRODUCTION

Targeted agents alone or in combination with chemotherapy are current standard of treatment for metastatic colorectal cancer (mCRC). Panitumumab is a fully human monoclonal antibody which inhibits the epidermal growth factor receptor (EGFR). It is currently approved in combination with chemotherapy in first- and second-line and as a monotherapy in chemorefractory patients. RAS gene mutations confer resistance to anti-EGFR agents; thus, panitumumab is restricted to the treatment of RAS wild-type (WT) tumors. Areas covered: This review explores the available data on panitumumab and presents new perspectives on predictive markers of anti-EGFR efficacy including primary tumor sidedness and BRAF mutations. Other details covered include panitumumab's mechanism of action, pharmacokinetics, pharmacodynamics and safety aspects of the therapy as well as mechanisms of secondary resistance and future prospects of treatment in different settings. Expert opinion: Panitumumab has significantly added to the treatment armamentarium for RAS WT mCRC. The effort spent in identifying predictive biomarkers of panitumumab efficacy has been of pivotal importance to development of the molecular selection of patients with mCRC. Primary and secondary resistance, however, still represent important issues. Novel strategies to overcome those issues are currently underway with promising results which highlight the potential use of panitumumab in combination with other targeted agents in the future.

Multicenter phase II study of infusional 5-fluorouracil (5-FU), leucovorin, and oxaliplatin, plus biweekly cetuximab as first-line treatment in patients with metastatic colorectal cancer (CELINE trial)

The current phase II study investigated the efficacy and safety of biweekly cetuximab combined with standard oxaliplatin-based chemotherapy [infusional 5-fluorouracil (5-FU), leucovorin, and oxaliplatin (FOLFOX-6)] in the first-line treatment of KRAS wild-type metastatic colorectal cancer (mCRC). Sixty patients with a median age of 64 years (range, 38-82 syears) received a biweekly intravenous infusion of cetuximab (500 mg/m² on day 1) followed by FOLFOX-6 (2-hour oxaliplatin 85 mg/m² infusion on day 1 in tandem with a 2-h leucovorin 200 mg/m² infusion on days 1 and 2, and 5-FU as a 400 mg/m² bolus followed by a 46-hour 2,400 mg/m² infusion on days 1-3). Patient response rate was 70%, with 95% disease control rates. The median progression-free survival was 13.8 months. Thirteen patients (21.7%) were able to undergo resection of previously unresectable metastases, with the aim of curing them. The median follow-up was 22.7 months, and median overall survival was 31.0 months. Cetuximab did not increase FOLFOX-6 toxicity and was generally well tolerated. The results of the current study demonstrate that the combination of biweekly cetuximab with FOLFOX-6 was well tolerated and had a manageable safety profile for the first-line treatment of KRAS wild-type metastatic colorectal cancer. Efficacy was comparable to other treatment regimens. The results support the administration of biweekly cetuximab in combination with FOLFOX-6, which may be more convenient and provide treatment flexibility in this setting for patients with metastatic colorectal cancers.

A Phase II Study of XELOX and Cetuximab as First-Line Therapy in Patients With KRAS Wild Type Metastatic Colorectal Cancer (FLEET2 Study)

BACKGROUND

Despite the comparable clinical benefit of XELOX (capecitabine with oxaliplatin) and FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin), the value of XELOX treatment in combination with cetuximab for metastatic colorectal cancer (mCRC) remains largely unknown.

PATIENTS AND METHODS

In this clinical trial we evaluated the efficacy and safety of weekly/biweekly cetuximab administration combined with biweekly XELOX in patients with previously untreated v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) wild type mCRC. The primary end point was response rate (RR) with confirmation, and the secondary end points included progression-free survival (PFS), overall survival (OS), disease control rate (DCR), dose intensity, and the safety of the protocol treatment.

RESULTS

Forty patients who fulfilled the inclusion criteria participated in this study. The median treatment cycle number was 8 and the median dose intensities were 218 mg/m²/wk for cetuximab, 34 mg/m²/wk for oxaliplatin, and 821 mg/m²/d for capecitabine. One patient showed complete response and partial response was observed in 19 patients, giving an overall RR of 50% (95% confidence interval [CI], 33.8%-66.2%). Stable disease was obtained in 13 patients, resulting in a DCR of 82.5% (95% CI, 67.2%-92.7%). The PFS was 6.5 months (95% CI, 3.5-9.6 months), and the OS was 24.3 months (95% CI, 14.9-33.7 months). The safety profile revealed the common Grade 3/4 adverse events to be acneiform eruption (12.5%), peripheral neuropathy (7.5%), and elevated alanine transaminase levels (7.5%). Grade 3/4 thrombocytopenia and neutropenia occurred only in 5.0% and 2.5% of the patients, respectively. Grade 1 hand-foot syndrome (HFS) was not uncommon (20%), whereas Grade 2/3 HFS occurred in only 3 patients (7.5%). No deaths were reported within 30 days of the last dose.

CONCLUSION

Cetuximab with XELOX showed a confirmed overall RR of 50%, which was within the previously reported range of RR. The safety profile showed an acceptable rate and severity of adverse events. In light of the several advantages of XELOX, including convenience and the reported cost-saving aspects, further study of this combination therapy is warranted.

Analysis of Impact of Post-Treatment Biopsies in Phase I Clinical Trials

PURPOSE

The use of biopsy-derived pharmacodynamic biomarkers is increasing in early-phase clinical trials. It remains unknown whether drug development is accelerated or enhanced by their use. We examined the impact of biopsy-derived pharmacodynamic biomarkers on subsequent drug development through a comprehensive analysis of phase I oncology studies from 2003 to 2010 and subsequent publications citing the original trials.

METHODS

We conducted a search to identify and examine publications of phase I oncology studies including the use of biopsy-derived pharmacodynamic biomarkers between 2003 and 2010. Characteristics of those studies were extracted and analyzed, along with outcomes from the biomarker data. We then compiled and reviewed publications of subsequent phase II and III trials citing the original phase I biomarker studies to determine the impact on drug development.

RESULTS

We identified 4,840 phase I oncology publications between 2003 and 2010. Seventy-two studies included a biopsy-derived pharmacodynamic biomarker. The proportion of biomarker studies including nondiagnostic biopsies increased over time (P = .002). A minimum of 1,873 tumor biopsies were documented in the 72 studies, 12 of which reported a statistically significant biomarker result. Thirty-three percent of studies (n = 24) were referenced by subsequent publications specifically with regard to the biomarkers. Only five positive biomarker studies were cited subsequently, and maximum tolerated dose was used for subsequent drug development in all cases.

CONCLUSION

Despite their increased use, the impact of biopsy-derived pharmacodynamic biomarkers in phase I oncology studies on subsequent drug development remains uncertain. No impact on subsequent dose or schedule was demonstrated. This issue requires further evaluation, given the risk and cost of such studies.

Multicenter Phase II study of FOLFOX or biweekly XELOX and Erbitux (cetuximab) as first-line therapy in patients with wild-type KRAS/BRAF metastatic colorectal cancer: The FLEET study

Background

The clinical benefit of cetuximab combined with oxaliplatin-based chemotherapy remains under debate. The aim of the present multicenter open-label Phase II study was to explore the efficacy and safety of biweekly administration of cetuximab and mFOLFOX-6 or XELOX as first-line chemotherapy in patients with metastatic colorectal cancer.

Methods

Sixty-two patients with previously untreated KRAS/BRAF wild-type metastatic colorectal cancer were recruited to the study between April 2010 and May 2011. Patients received one of two treatment regimens, either cetuximab plus mFOLFOX-6 (FOLFOX + Cmab) or cetuximab plus biweekly XELOX (XELOX + Cmab), according to their own preference. Treatment was continued until disease progression or the appearance of intolerable toxicities. The primary endpoint was response rate; secondary endpoints were progression-free survival, overall survival, disease control rate, dose intensity, conversion rate to surgical resection, and safety.

Results

The response rates in the FOLFOX + Cmab (n = 37) and XELOX + Cmab (n = 25) groups were 64.9 % (24/37) and 72.0 % (18/25), respectively. The median PFS in the FOLFOX + Cmab and XELOX + Cmab groups was 13.1 months (95 % confidence interval [CI] 12.1–17.5) and 13.4 months (95 % CI 10.1–17.9), respectively. Neutropenia was the most frequent grade 3/4 adverse event in both groups (33.9 %), followed by anorexia, acneiform eruption, skin fissure and paronychia. A waterfall plot of tumor diameter showed prominent shrinkage of the tumors in 88.7 % of patients.

Conclusions

The results of the present study indicate that biweekly cetuximab plus mFOLFOX-6/XELOX is an effective and tolerable treatment regimen. Biweekly administration of cetuximab requires only one hospital visit every 2 weeks, and may become a convenient treatment option for patients with KRAS/BRAF wild-type metastatic colorectal cancer.

Trial registration

This study is registered with University Hospital Medical Information Network (UMIN 000003253). Registration date is 02/24/2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1685-z) contains supplementary material, which is available to authorized users.

Circulating Tumor Cell Enumeration in a Phase II Trial of a Four-Drug Regimen in Advanced Colorectal Cancer

BACKGROUND

Multidrug regimens are active against advanced colorectal cancer (ACRC). However, the increased toxicity requires the use of biomarkers to select the patients who will derive the most benefit. We assessed circulating tumor cells (CTCs) as a prognostic biomarker in patients treated with a 4-drug regimen.

PATIENTS AND METHODS

A single-arm phase II trial (Erbitux Study of CPT11, Oxaliplatin, UFToral Targeted-therapy [eSCOUT]) was undertaken in patients with previously untreated KRAS wild-type ACRC using a regimen of irinotecan, oxaliplatin, and tegafur-uracil with leucovorin and cetuximab. Baseline CTCs were enumerated using CellSearch. The endpoints were an objective response rate (ORR) and overall survival (OS). We modeled our results and compared them with those modeled for the capecitabine, oxaliplatin, bevacizumab +/- cetuximab (CAIRO2) trial, stratifying patients a priori into low (< 3) and high (≥ 3) CTC groups.

RESULTS

For 48 eligible patients, the best ORR from the 4-drug regimen was 71%, with a disease control rate of 98%. The median OS for patients with a high and low CTC count was 18.7 and 22.3 months (log-rank test, P = .038), respectively. In our modeled data, for patients with a low CTC count, no differences were found between the median OS in the eSCOUT trial and that in the CAIRO2 trial (22.2 vs. 22.0 months). However, for the high CTC group, a clinically relevant improvement was seen in median OS (eSCOUT vs. CAIRO2, 18.7 vs. 13.7 months; P = .001).

CONCLUSION

These data are hypothesis generating-for patients with ACRC, stratification by CTC count can identify those who might benefit the most from an intensive 4-drug regimen, avoiding high-toxicity regimens in low CTC groups. This hypothesis warrants validation in a phase III biomarker-driven trial.

The molecular landscape of colorectal cancer cell lines unveils clinically actionable kinase targets

The development of molecularly targeted anticancer agents relies on large panels of tumour-specific preclinical models closely recapitulating the molecular heterogeneity observed in patients. Here we describe the mutational and gene expression analyses of 151 colorectal cancer (CRC) cell lines. We find that the whole spectrum of CRC molecular and transcriptional subtypes, previously defined in patients, is represented in this cell line compendium. Transcriptional outlier analysis identifies RAS/BRAF wild-type cells, resistant to EGFR blockade, functionally and pharmacologically addicted to kinase genes including ALK, FGFR2, NTRK1/2 and RET. The same genes are present as expression outliers in CRC patient samples. Genomic rearrangements (translocations) involving the ALK and NTRK1 genes are associated with the overexpression of the corresponding proteins in CRC specimens. The approach described here can be used to pinpoint CRCs with exquisite dependencies to individual kinases for which clinically approved drugs are already available.

FOLFIRI and Cetuximab Every Second Week for First-Line Treatment of KRAS Wild-Type Metastatic Colorectal Cancer According to Phosphatase and Tensin Homolog Expression: A Phase II Study

BACKGROUND

Retrospective studies have suggested that phosphatase and tensin homolog (PTEN) expression might predict the efficacy of cetuximab in patients with KRAS wild-type metastatic colorectal cancer (mCRC). The present study was designed to prospectively evaluate the efficacy of first-line irinotecan, fluorouracil, and folinate (FOLFIRI) plus cetuximab every second week according to PTEN expression.

PATIENTS AND METHODS

Originally, patients with KRAS wild-type mCRC were randomly assigned to receive either FOLFIRI or cetuximab plus FOLFIRI (FOLFIRI-C). After a protocol amendment, the FOLFIRI arm was discontinued, and additional patients received FOLFIRI-C. Cox proportional hazard models were used to investigate the effect of PTEN and MET expression and BRAF and phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit α mutations on progression-free survival (PFS) and overall survival (OS).

RESULTS

A total of 35 and 54 patients received FOLFIRI and FOLFIRI-C, respectively. For the patients assigned to FOLFIRI and FOLFIRI-C, the median OS was 17.7 and 23.3 months and the median PFS was 8.2 and 6.6 months, respectively. For patients receiving FOLFIRI-C, the loss of PTEN expression did not affect PFS or OS. Significant interactions for PFS were detected between the MET expression levels (P = .047) and BRAF mutation (P = .018) and treatment. On univariate analysis, BRAF mutation was significantly associated with shorter OS for patients receiving either FOLFIRI-C (P = .016) or FOLFIRI (P = .035). Multivariate analysis confirmed the independent prognostic value of BRAF mutation on OS and that of MET expression levels on PFS (P = .025) and OS (P = .028) but only in the patients receiving FOLFIRI alone. Adverse events with FOLFIRI-C were consistent with those expected from FOLFIRI plus weekly cetuximab.

CONCLUSION

Although prospective analysis of PTEN did not allow a validation of the prognostic value of this biomarker, an every second week cetuximab schedule, in addition to first-line FOLFIRI, was effective and well tolerated. The possible predictive value of MET expression levels warrants additional investigation.

Biweekly cetuximab in combination with FOLFOX-4 in the first-line treatment of wild-type KRAS metastatic colorectal cancer: final results of a phase II, open-label, clinical trial (OPTIMIX-ACROSS Study)

BACKGROUND

This phase II study aims to evaluate the efficacy and safety of biweekly cetuximab in combination with oxaliplatin, leucovorin, and fluorouracil (FOLFOX-4) as first-line treatment of metastatic wild-type KRAS colorectal cancer.

METHODS

Previously untreated patients with wild-type KRAS tumours received biweekly cetuximab (500 mg/m2 on day 1) plus FOLFOX-4 (oxaliplatin 85 mg/m2 on day 1, leucovorin 200 mg/m2 on days 1 and 2, and fluorouracil as a 400 mg/m2 bolus followed by a 22-hour 600 mg/m2 infusion on day 1 and 2). Treatment was continued until disease progression, onset of unacceptable toxicities, metastases surgery, or discontinuation request. The primary endpoint was ORR.

RESULTS

The intention-to-treat population included 99 patients with a median age of 64.1 years (range, 34-82). The ORR was 60.6% (95% CI, 50.3% to 70.3%). The median follow-up was 17.8 months; the median OS and PFS were 20.8 and 10.1 months, respectively. Metastases from colorectal cancer were surgically resected in 26 (26.3%) patients, with complete resection achieved in 18 (69.2%) patients. Median PFS and OS in patients undergoing metastatic resection were 12.6 and 29.5 months, respectively. The most common grade 3-4 toxicities were neutropenia (32.3%), acne-like rash (15.2%) and diarrhoea (11.1%).

CONCLUSIONS

The efficacy of the biweekly combination of cetuximab with FOLFOX-4 in patients with wild-type KRAS tumours supports the administration of cetuximab in a dosing regimen more convenient for patients and healthcare providers. The activity of the biweekly administration is similar to what has been reported for the weekly regimen. Reported toxicity was also consistent with the known toxicity profile of weekly cetuximab.

TRIAL REGISTRATION

EudraCT Number 200800690916.

Gemcitabine and oxaliplatin with or without cetuximab in advanced biliary-tract cancer (BINGO): a randomised, open-label, non-comparative phase 2 trial

BACKGROUND

Gemcitabine plus a platinum-based agent (eg, cisplatin or oxaliplatin) is the standard of care for advanced biliary cancers. We investigated the addition of cetuximab to chemotherapy in patients with advanced biliary cancers.

METHODS

In this non-comparative, open-label, randomised phase 2 trial, we recruited patients with locally advanced (non-resectable) or metastatic cholangiocarcinoma, gallbladder carcinoma, or ampullary carcinoma and a WHO performance status of 0 or 1 from 18 hospitals across France and Germany. Eligible patients were randomly assigned (1:1) centrally with a minimisation procedure to first-line treatment with gemcitabine (1000 mg/m(2)) and oxaliplatin (100 mg/m(2)) with or without cetuximab (500 mg/m(2)), repeated every 2 weeks until disease progression or unacceptable toxicity. Randomisation was stratified by centre, primary site of disease, disease stage, and previous treatment with curative intent or adjuvant therapy. Investigators who assessed treatment response were not masked to group assignment. The primary endpoint was the proportion of patients who were progression-free at 4 months, analysed by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00552149.

FINDINGS

Between Oct 10, 2007, and Dec 18, 2009, 76 patients were assigned to chemotherapy plus cetuximab and 74 to chemotherapy alone. 48 (63%; 95% CI 52-74) patients assigned to chemotherapy plus cetuximab and 40 (54%; 43-65) assigned to chemotherapy alone were progression-free at 4 months. Median progression-free survival was 6·1 months (95% CI 5·1-7·6) in the chemotherapy plus cetuximab group and 5·5 months (3·7-6·6) in the chemotherapy alone group. Median overall survival was 11·0 months (9·1-13·7) in the chemotherapy plus cetuximab group and 12·4 months (8·6-16·0) in the chemotherapy alone group. The most common grade 3-4 adverse events were peripheral neuropathy (in 18 [24%] of 76 patients who received chemotherapy plus cetuximab vs ten [15%] of 68 who received chemotherapy alone), neutropenia (17 [22%] vs 11 [16%]), and increased aminotransferase concentrations (17 [22%] vs ten [15%]). 70 serious adverse events were reported in 39 (51%) of 76 patients who received chemotherapy plus cetuximab (34 events in 19 [25%] patients were treatment-related), whereas 41 serious adverse events were reported in 25 (35%) of 71 patients who received chemotherapy alone (20 events in 12 [17%] patients were treatment-related). One patient died of atypical pneumonia related to treatment in the chemotherapy alone group.

INTERPRETATION

The addition of cetuximab to gemcitabine and oxaliplatin did not seem to enhance the activity of chemotherapy in patients with advanced biliary cancer, although it was well tolerated. Gemcitabine and platinum-based combination should remain the standard treatment option.

FUNDING

Institut National du Cancer, Merck Serono.

Biweekly cetuximab plus FOLFIRI/irinotecan as first/second-line chemotherapy for patients with KRAS wild-type metastatic colorectal cancer: a retrospective analysis in Southwest Chinese population

Weekly cetuximab plus irinotecan-based regiments are standard first- and second-line chemotherapy for patients with KRAS wild-type metastatic colorectal cancer (mCRC). However, the chemotherapy regimens are given every 2 weeks, which is asynchronous with cetuximab weekly administration. This study investigated the efficacy and safety of biweekly cetuximab administration in patients with mCRC. Twenty-six patients with KRAS wild-type mCRC, who received biweekly cetuximab plus FOLFIRI/irinotecan as first/second-line chemotherapy, at least three cycles of cetuximab and once CT evaluation in West China Hospital from May 2010 to February 2013, were retrospectively analyzed. The median number of cetuximab administrations was 8.3 (range 3-20). Fourteen patients received FOLFIRI as first-line therapy; response rate was 50.0%; median PFS was 8.8 months (95% CI 4.9-12.7). Ten patients received FOLFIRI and two patients received irinotecan as second-line therapy; response rate was 33.3%; median PFS was 4.6 months (95% CI 0.9-8.3). The toxicity was similar to weekly cetuximab combination schedules. Rash was observed in 69.2% of evaluable patients (grade 3 in 7.7%). Overall, our results show that biweekly cetuximab plus FOLFIRI/irinotecan may be as effective and safe as the standard weekly schedule.

FOLFOX4 plus cetuximab administered weekly or every second week in the first-line treatment of patients with KRAS wild-type metastatic colorectal cancer: a randomized phase II CECOG study

BACKGROUND

This randomized phase II study investigated first-line chemotherapy plus cetuximab administered every second week in KRAS wild-type metastatic colorectal cancer.

PATIENTS AND METHODS

Patients received FOLFOX4 plus either standard weekly cetuximab (arm 1) or cetuximab (500 mg/m(2)) every second week (arm 2), until disease progression or unacceptable toxicity. Primary end point was the objective response rate (ORR). Progression-free survival (PFS), overall survival (OS), disease control rate (DCR) and safety were also investigated. The study was not powered to establish non-inferiority, but aimed at the estimation of treatment differences.

RESULTS

Of 152 randomized eligible patients, 75 were treated in arm 1 and 77 in arm 2; ORRs [53% versus 62%, odds ratio 1.40, 95% confidence interval (CI) 0.74-2.66], PFS [median 9.5 versus 9.2 months, hazard ratio (HR) 0.92, 95% CI 0.63-1.34], OS (median 25.8 versus 23.0 months, HR 0.86, 95% CI 0.56-1.30) and DCR (87%) were comparable. HRs adjusted for baseline factors were 1.01 and 0.99 for PFS and OS, respectively. Frequencies of grade 3/4 adverse events in arms 1 versus 2 were similar: most common were neutropenia (28% versus 34%) and rash (15% versus 17%).

CONCLUSIONS

Activity and safety of FOLFOX4 plus either cetuximab administered weekly or every second week were similar.

Randomized controlled trial of cetuximab plus chemotherapy for patients with KRAS wild-type unresectable colorectal liver-limited metastases

PURPOSE

To assess the effects of cetuximab plus chemotherapy as first-line treatment for unresectable colorectal liver metastases (CLMs).

PATIENTS AND METHODS

After resection of their primary tumors, patients with KRAS wild-type synchronous nonresectable liver-limited metastases from colorectal cancer were randomly assigned to receive chemotherapy (FOLFIRI [fluorouracil, leucovorin, and irinotecan] or mFOLFOX6 [modified fluorouracil, leucovorin, and oxaliplatin]) plus cetuximab (arm A) or chemotherapy alone (arm B). The primary end point was the rate of patients converted to resection for liver metastases. Secondary end points included tumor response and survival.

RESULTS

The intent-to-treat population comprised 138 patients; 70 patients were randomly assigned to arm A and 68 to arm B. After a median of 25.0 months of follow-up, the 3-year overall survival (OS) rate and median survival time (MST) for all patients were 30% and 24.4 months, respectively. The R0 resection rates for liver metastases were 25.7% (18 of 70 patients) in arm A and 7.4% (five of 68 patients) in arm B, which were significantly different (P < .01). Patients in arm A had improved objective response rates (57.1% v 29.4%; P < .01), increased 3-year OS rate (41% v 18%; P = .013) and prolonged MST (30.9 v 21.0 months; P = .013) compared with those in arm B. In addition, in arm A, patients who had resection of liver metastases had a significantly improved MST (46.4 v 25.7 months; P < .01) compared with those who did not undergo surgery.

CONCLUSION

For patients with initially unresectable KRAS wild-type CLMs, cetuximab combined with chemotherapy improved the resectability of liver metastases and improved response rates and survival compared with chemotherapy alone.