Successful long-term management of a patient with late-stage metastatic colorectal cancer treated with panitumumab

INTRODUCTION

Recent approval and introduction into clinical practice of epidermal growth factor receptor inhibitors such as the chimeric monoclonal antibody cetuximab and the fully human monoclonal antibody panitumumab have provided new treatment options for chemotherapy-refractory patients. Here, we report a case of a 47-year-old man with metastatic, chemotherapy-refractory colorectal cancer who achieved long-term partial remission during panitumumab therapy.

CASE PRESENTATION

A 41-year-old male patient presented with a 24-hour history of abdominal pain and fever. A computed tomography (CT) scan revealed a voluminous and perforated abscess with a suspected tumour lesion in the sigmoid colon. The patient underwent sigmoidectomy and was diagnosed with a poorly differentiated necrotic carcinoma of the sigmoid colon with invasion in 13 of 19 tested lymph nodes. A colonoscopy revealed multiple tubular adenomas and a positron emission tomography CT scan showed multiple and bilateral hyperfixating lumbar-aortic lymph nodes leading to a final tumour classification of T4N2M1. Carcinoembryonic antigen (CEA) was elevated. The patient achieved a partial response following six cycles of FOLFIRI (irinotecan, 5-fluorouracil, leucovorin), then progressed and was enrolled in a trial where he received treatment with FOLFOX4 (oxaliplatin, leucovorin and 5-fluorouracil) with or without a vascular endothelial growth factor inhibitor (PTK787/ZK 222584 [valatinib]). Eight months later he progressed again and was included in a panitumumab (6mg/kg every 2 weeks) monotherapy trial. A partial response was noted after 8 weeks of therapy along with a rapid CEA reduction and decrease in lymph node size. The patient is continuing panitumumab treatment and is still in partial remission after 65 months' treatment. He has non-mutated KRAS and no human-anti-human antibodies have been detected. During treatment the patient has on occasion experienced grade 1-2 diarrhoea as well as folliculitis and acne-like rash up to grade 3 in severity. Cutaneous toxicity was managed with a combination dose interruption/reduction and the use of topical agents. No eye or nail toxicities occurred.

CONCLUSION

This case shows that long-term responses are possible during panitumumab therapy and that this agent may be an effective long-term treatment option for selected patients with metastatic colorectal cancer. The associated skin toxicities can be successfully managed.

Amphiregulin and epiregulin mRNA expression in primary tumors predicts outcome in metastatic colorectal cancer treated with cetuximab

PURPOSE

To study the power of the epidermal growth factor receptor (EGFR) epiregulin (EREG) and amphiregulin (AREG) ligands' expression in primary tumors to predict the outcome in patients with chemorefractory metastatic colorectal cancer (cmCRC) treated with the combination of cetuximab and irinotecan.

PATIENTS AND METHODS

Gene expression measurements and KRAS mutation analysis were performed on archival formalin-fixed paraffin-embedded primary tumors of 220 cmCRC patients. Response was measured using RECIST (Response Evaluation Criteria in Solid Tumors) criteria. The relation between ligand expression levels and outcome was evaluated using logistic regression for response and Cox regression for survival data. Receiver operating characteristics analysis was performed for response and survival data. CIs for the performance indices were obtained with a nonparametric bootstrap procedure. Findings were externally validated on a series of 67 samples treated in a similar setting.

RESULTS

In KRAS wild type (WT) patients, there was a significant association between log-transformed ligand expression and response for EREG (odds ratio for objective response, 1.90; 95% CI, 1.27 to 2.83; P = .0005; concordance index [c-index], 0.681) and for AREG (odds ratio for objective response, 1.862; 95% CI, 1.22 to 2.72; P = .0017; c-index, 0.673). In a Cox regression model, dichotomized ligand expression was significantly associated with progression-free survival (PFS) and overall survival (OS). EREG PFS hazard ratio (HR) was 0.41 (95% CI, 0.274 to 0.609; P < .001; time-dependent c-index [Ctau index], 0.640), and AREG PFS HR was 0.43 (95% CI, 0.29 to 0.64; P < .001; Ctau index, 0.627). EREG OS HR was 0.42 (95% CI, 0.28 to 0.63; P < .0001; Ctau index, 0.639), and AREG OS HR was 0.40 (95% CI, 0.27 to 0.64; P < .0001; Ctau index, 0.625). There was no predictive power of ligand expression in patients with KRAS mutation.

CONCLUSION

Expression of EGFR ligands in primary tumors significantly predicts outcome in KRAS WT cmCRC treated with cetuximab and irinotecan.

Rash as a marker for the efficacy of gemcitabine plus erlotinib-based therapy in pancreatic cancer: Results from the AViTA Study

4532

Background: The EGFR inhibitor, erlotinib (E), in combination with gemcitabine (G), provides a significant survival benefit in metastatic pancreatic cancer. Rash, a common toxicity with EGFR inhibitors, has been proposed as a potential marker of erlotinib efficacy in multiple tumor types. The recent phase III study of GE ± bevacizumab (B) (Vervenne et al. ASCO 2008) provides a further opportunity to consider this topic. Methods: Chemo-naïve patients (pts) with metastatic pancreatic adenocarcinoma and KPS of 60–100 were randomized to GE-placebo (GE-P) or GE-B; pts received B/P 5mg/kg q2w plus E (100mg/d) and G (1,000mg/m2) given weekly for 7 weeks during the first 8-weekly cycle, followed by weekly for 3 weeks during subsequent 4-weekly cycles. Results: 607 pts were recruited; the arms were well balanced with respect to baseline characteristics. The addition of B to GE produced a significant benefit in PFS (hazard ratio [HR] 0.73, p=0.0002), and a trend towards longer OS (HR 0.89, p = 0.2087; median 7.1 mo vs 6.0 mo for GE-P). GE-B was well tolerated with no new safety signals observed. The incidence of rash was higher in the GE-B arm (73% vs 62% in the GE-P arm). There was a clear trend towards longer OS with increased grade of rash (see table ); this trend was apparent in both arms of the study. There was no difference in OS between treatment groups for any rash grade. Conclusions: The observed relationship between higher grades of rash and longer median OS supports the findings of the phase III PA.3 study of G ± E (Moore et al. JCO 2007), in pts with advanced pancreatic cancer. Studies are under way to prospectively investigate the relationship between rash and efficacy with erlotinib-based regimens in pancreatic cancer.

[Table: see text]

[Table: see text]

Phase III trial of bevacizumab in combination with gemcitabine and erlotinib in patients with metastatic pancreatic cancer

PURPOSE

Treatment with gemcitabine provides modest benefits in patients with metastatic pancreatic cancer. The addition of erlotinib to gemcitabine shows a small but significant improvement in overall survival (OS) versus gemcitabine alone. Phase II results for bevacizumab plus gemcitabine provided the rationale for a phase III trial of gemcitabine-erlotinib plus bevacizumab or placebo.

PATIENTS AND METHODS

Patients with metastatic pancreatic adenocarcinoma were randomly assigned to receive gemcitabine (1,000 mg/m(2)/week), erlotinib (100 mg/day), and bevacizumab (5 mg/kg every 2 weeks) or gemcitabine, erlotinib, and placebo in this double-blind, phase III trial. Primary end point was OS; secondary end points included progression-free survival (PFS), disease control rate, and safety.

RESULTS

A total of 301 patients were randomly assigned to the placebo group and 306 to the bevacizumab group. Median OS was 7.1 and 6.0 months in the bevacizumab and placebo arms, respectively (hazard ratio [HR], 0.89; 95% CI, 0.74 to 1.07; P = .2087); this difference was not statistically significant. Adding bevacizumab to gemcitabine-erlotinib significantly improved PFS (HR, 0.73; 95% CI, 0.61 to 0.86; P = .0002). Treatment with bevacizumab plus gemcitabine-erlotinib was well tolerated: safety data did not differ from previously described safety profiles for individual drugs.

CONCLUSION

The primary objective was not met. The addition of bevacizumab to gemcitabine-erlotinib did not lead to a statistically significant improvement in OS in patients with metastatic pancreatic cancer. PFS, however, was significantly longer in the bevacizumab group compared with placebo. No unexpected safety events were observed from adding bevacizumab to gemcitabine-erlotinib.

A dose-finding and pharmacokinetic study of I.V. vinflunine in combination with doxorubicin as first line treatment of metastatic breast cancer

Abstract #6124

Background: VFL is a novel bifluorinated tubulin-targeted agent of the vinca alkaloids class. In a phase II study in anthracycline and taxane pretreated MBC patients (pts), an ORR of 30% observed. Given activity shown by DXR or VFL in MBC, we conducted a phase I study of the combination, define maximum tolerated dose (MTD), recommended dose (RD), safety (NCI CTC 2.0), PK interaction and efficacy (Recist).&#x2028; Methods: 2 schedules investigated (VFL D1 with DXR D1, every 3 weeks and VFL Ds 1 and 8, with DXR Ds 1 and 8, every 3 weeks). Eligibility: Pts with MBC, previously untreated for metastatic disease; could have received adj/neoadjuvant with anthracycline-containing regimen, cumulative doses &lt; 250 mg/m² for DXR, 450 mg/m² for EPI. Dose escalation used 3+3 design; PK samples were obtained for VFL and DXR to investigate potential interaction.&#x2028; &#x2028; Results: 32 patients were enrolled (15 patients in schedule 1 and 17 in schedule 2) and received escalating doses of VFL and DXR.&#x2028; In schedule 1, 2 dose levels (DL) were investigated; At DL VFL250/DXR50, 8 pts were treated with 6 patients evaluable for DLT, where 2 DLTs were identified consisting of neutropenia &lt; 0.1x109/l &gt; 3 days and a neutropenic infection; then this DL was considered MTD; at the DL VFL250/DXR40, 7 pts were treated without developing DLTs then considered RD. 73 cycles were administered (median 6); Most frequent haematological toxicity was neutropenia, gr 3 in 1 pt and gr 4 in 11 pts. Main non-haematological adverse events were: nausea 80%, fatigue 73.3%, constipation 40%, vomiting 40%, anorexia 33.3%, stomatitis 20%, dyspnea 13.3%. Clinical activity: 7 pts (46.7%) had PR, and 4 pts (26.7%) SD. No PK interaction was detected.&#x2028; In schedule 2, at DL VFL150/DXR25, 6 of 9 pts were evaluable in whom 2 Gr 4 neutropenia &gt; 7 days occurred, (DL considered as MTD). In the DL below VFL120/DXR25, 6 of 8 pts were evaluable, only 1 Gr 4 neutropenia &gt; 7 days occurred, (DL considered RD). A total of 89 cycles (median 6) were administered; neutropenia was the main haematological toxicity, with Gr ¾ in 14 pts (82.4%); main non-haematological toxicities: fatigue 82.4%, constipation 76.5%, nausea 76.5%, vomiting 64.7%, stomatitis 41.2%, dyspnea 41.2%, anorexia 35.3%; no episode of Gr 4 occurred.&#x2028; Among 17 treated pts, 8 (47.1%) had PR and 6 (35.3%) SD. PK analysis ongoing.&#x2028; Conclusion: RD for schedule 1 is VFL250/DXR40 on day 1, Q3W, for schedule 2, VFL120/DXR25 on days 1 and 8, Q3W. Overall VFL/DXR combination is feasible and toxicity was manageable, where haematological toxicity was frequent but reversible. Promising antitumour activity was detected.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6124.

Clinical usefulness of EGFR gene copy number as a predictive marker in colorectal cancer patients treated with cetuximab: a fluorescent in situ hybridization study

PURPOSE

To evaluate the usefulness and the pitfalls inherent to the assessment of the epidermal growth factor receptor (EGFR) gene copy number (GCN) by fluorescence in situ hybridization (FISH) for outcome prediction to cetuximab in metastatic colorectal cancer. The value of testing KRAS mutation status, in addition to EGFR GCN, was also explored.

EXPERIMENTAL DESIGN

FISH analysis of 87 metastatic colorectal cancer patients treated with cetuximab was done, recording individual GCN per cell and using different samples per tumor. Performances of published cutoff points and different summaries of EGFR GCN distribution were assessed for response prediction.

RESULTS

In our data set, two published cutoff points performed less well than in their training set, yielding positive predictive values and negative predictive values between 40.0% and 48.3% and between 81.0% and 86.5%, respectively. Among summaries of GCN distribution explored, mean and right-tailed distribution of GCN yielded the highest performances. A mean EGFR GCN > or = 2.83 provided an area under the curve of 0.71. Important heterogeneity of repeated measures of mean EGFR GCN was observed within tumors (intraclass correlation, 0.61; within-class SD, 0.40), leading to potential misclassifications of FISH status in 7 of 18 (38.8%) patients if a cutoff point were used. In multivariable analysis, EGFR GCN testing provided significant information independent of the KRAS status to predict response (P = 0.016) and overall survival (P = 0.005).

CONCLUSIONS

We confirm the association between increased EGFR GCN and outcome after cetuximab. However, because of reproducibility concerns, any decision making based on published cutoff points is not warranted.

Validation of Patient's Self-Reported Social Functioning As an Independent Prognostic Factor for Survival in Metastatic Colorectal Cancer Patients: Results of an International Study by the Chronotherapy Group of the European Organisation for Research and Treatment of Cancer

Purpose

A recent study identified a prognostic model for survival in metastatic colorectal cancer patients which included WBC count, alkaline phosphatase (AP), number of metastatic sites, and patients’ self-reported social functioning. The aim of this research is to validate this model on data from an independent sample.

Patients and Methods

This validation study is based on a prospective randomized controlled trial in patients with metastatic colorectal cancer conducted by the European Organisation for Research and Treatment of Cancer (EORTC) Chronotherapy Group. Overall, 564 patients in 10 countries were enrolled. For the purpose of this independent validation, patients with health-related quality of life (HRQOL) baseline data were analyzed. HRQOL was assessed using the EORTC Quality of Life Questionnaire C30 (QLQ-C30). The Cox proportional hazards regression model was used for both univariate and multivariate analyses of survival.

Results

The previous model with an additional adjustment, by stratification for sex, was replicated and its parameters were confirmed to independently predict survival: WBC count with an hazard ratio (HR) of 1.31 (95% CI, 1.021 to 1.698; P = .034); AP with an HR of 1.53 (95% CI, 1.188 to 1.979; P = .001); number of sites involved with an HR of 1.90 (95% CI, 1.531 to 2.364; P < .0001); and patients’ self-reported social functioning with an HR of 0.94 (95% CI, 0.905 to 0.976; P = .001). The latter translates into a 6% increase in the likelihood of an earlier death for every 10-point decrease in the social functioning scale of the EORTC QLQ-C30.

Conclusion

This study provides confirmatory evidence of the independent prognostic value of patients’ self-reported social functioning in patients with advanced colorectal cancer.

Phase II trial of cetuximab in combination with fluorouracil, leucovorin, and oxaliplatin in the first-line treatment of metastatic colorectal cancer

PURPOSE

This phase II study investigated the efficacy and safety of cetuximab combined with standard oxaliplatin-based chemotherapy (infusional fluorouracil, leucovorin, and oxaliplatin [FOLFOX-4]) in the first-line treatment of epidermal growth factor receptor-expressing metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

The activity of cetuximab plus oxaliplatin was investigated in colon cancer cell lines and xenograft models. In the clinical study, patients with mCRC received on day 1 of a 14 day cycle, cetuximab (initial dose 400 mg/m(2) during week 1, then 250 mg/m(2) weekly) followed by FOLFOX-4 (oxaliplatin 85 mg/m(2) on day 1; leucovorin 200 mg/m(2) on days 1 and 2, followed by fluorouracil 400 mg/m(2) bolus then 600 mg/m(2) intravenous infusion during 22 hours on days 1 and 2).

RESULTS

The preclinical studies confirmed the supra-additive activity of cetuximab to oxaliplatin. In the clinical study, 43 patients were included, with a median age of 65 years (range, 43 to 78 years). Response rates (RRs) were 79% (unconfirmed) and 72% (confirmed), with 95% disease control. Median progression-free survival (mPFS) and median duration of response were 12.3 and 10.8 months, respectively. Ten patients (23%) underwent resection with curative intent of previously unresectable metastases. After a median follow-up of 30.5 months, median overall survival (mOS) was 30.0 months. Cetuximab did not increase the characteristic toxicity of FOLFOX-4 and was generally well tolerated.

CONCLUSION

Cetuximab in combination with FOLFOX-4 is a highly active first-line treatment for mCRC, showing encouraging RR, mPFS, and mOS values. The treatment resulted in a high resectability rate, which could potentially result in an improved cure rate. This combination is under phase III development.

KRAS wild-type state predicts survival and is associated to early radiological response in metastatic colorectal cancer treated with cetuximab

BACKGROUND

KRAS mutation status is a candidate marker for predicting survival in patients with metastatic colorectal cancer (mCRC) treated with cetuximab (CTX).

PATIENTS AND METHODS

We studied the KRAS mutation status of 113 patients with irinotecan refractory mCRC treated with CTX in clinical trials. A predictive model for objective response (OR), progression-free survival (PFS) and overall survival (OS) was constructed using logistic and Cox regression.

RESULTS

OR was seen in 27 of 66 KRAS wild-type (WT) patients versus 0 of 42 in KRAS mutants. Median OS was significantly better in KRAS WT versus mutants (43.0 versus 27.3 weeks; P = 0.020). Decrease in tumor sizes was significantly larger at all time points in WT patients. KRAS WT patients with an initial relative decrease of tumor size >9.66% at week 6 had a significantly better median OS compared with all other patients (74.9 versus 30.6 weeks; P = 0.0000025). Within KRAS WT patients OS was significantly better in patients with an initial decrease compared with those without [median OS: 74.9 versus 30.6 weeks (P = 0.00000012)].

CONCLUSIONS

KRAS WT status is associated to survival benefit in CTX treated mCRC. This benefit is even more pronounced in those patients with early radiological response. These characteristics may be exploited for response prediction.

Bronchobiliary fistula and cholangiocarcinoma: a case report and principles of management

A 64-year-old woman was admitted with fever and cough. At admission, she had jaundice, hepatomegaly, and green-stained sputum. Computed tomography (CT) showed an intrahepatic abscess located near the dome, multiple hepatic metastases, biliary tract dilatation, and a right pleural effusion. Percutaneous transhepatic cholangiography demonstrated a communication between the intrahepatic biliary ducts and the bronchial tree. The patient was treated with antibiotic therapy, pleural and biliary drainages and a percutaneous drainage of the hepatic abscess.

Cost-effectiveness of cetuximab in combination with irinotecan compared with current care in metastatic colorectal cancer after failure on irinotecan--a Belgian analysis

This analysis compared the cost-effectiveness in Belgium of cetuximab plus irinotecan with current current care in the treatment of epidermal growth factor receptor (EGFR)-expressing metastatic colorectal cancer (CRC) that has failed irinotecan-containing therapy. Treatment outcomes and medical resource use data for patients receiving cetuximab plus irinotecan from the BOND study were compared with those from a matched group of patients (current care) (n = 66). Two scenarios were considered in which cetuximab was discontinued either at 6 weeks or at 12 weeks if there was no tumour response at those time points. Cost-effectiveness was expressed in Euros as the additional cost per additional life year gained (LYG) (referred to as the incremental cost-effectiveness ratio (ICER)). For the 6-week rule, the ICERs were Euro 17000 compared with current care. For the 12-week rule, the ICER was Euro 40000 /LYG. Sensitivity analyses revealed that, in the worst case, considering all assumptions against the cetuximab combination, the maximum ICER is Euro 30000 or Euro 59000. In conclusion, cetuximab plus irinotecan for patients with metastatic CRC, after failure on irinotecan-containing chemotherapy, is rather cost-effective compared with current care in both scenarios tested.

An open-label, single-arm study assessing safety and efficacy of panitumumab in patients with metastatic colorectal cancer refractory to standard chemotherapy

BACKGROUND

A phase 3 study demonstrated that panitumumab, a human monoclonal anti-epidermal growth factor receptor antibody, significantly prolonged progression-free survival versus best supportive care (BSC) in patients with chemorefractory metastatic colorectal cancer.

PATIENTS AND METHODS

This open-label extension study evaluated panitumumab monotherapy in BSC patients with radiographically documented disease progression in the phase 3 study. Patients received panitumumab 6 mg/kg every 2 weeks. The primary end point was safety; efficacy was also evaluated.

RESULTS

One hundred and seventy-six patients were randomly assigned to the BSC arm of the phase 3 study received >/=1 panitumumab dose in this extension study. Panitumumab was well tolerated. The most frequent treatment-related adverse events were skin toxic effects. Three (2%) patients had a grade 4 treatment-related adverse event. There were no infusion reactions. One (0.6%) patient had a complete response; 19 (11%) patients had a partial response; and 58 (33%) patients had stable disease. Median progression-free survival time was 9.4 [95% confidence interval (CI): 8.0-13.4) weeks. Median overall survival time was 6.3 (95% CI: 5.1-6.8) months. Anti-panitumumab antibodies were detected in 3 (4.2%) of 71 patients with a post-baseline sample.

CONCLUSIONS

These findings are comparable to those from the phase 3 study and support panitumumab monotherapy for chemorefractory colorectal cancer.

Nodular regenerative hyperplasia: a deleterious consequence of chemotherapy for colorectal liver metastases?

AIMS

This report describes three patients suffering from nodular regenerative hyperplasia (NRH).

METHODS

These patients have received six, 16 and 20 cycles of neoadjuvant 5-fluorouracil and oxaliplatin-based chemotherapy before planned extended hepatectomy. Two patients underwent uneventful portal vein embolization to hypertrophy the future remnant liver.

RESULTS

At the end of chemotherapy, liver function tests deteriorated and portal hypertension appeared in two patients, including ascites, splenomegaly and oesophageal varices. Liver biopsy was performed through a percutaneous (two patients) or a transjugular approach (one patient) and allowed the diagnosis of NRH, which was considered to be a contraindication for major liver resection in all three patients, associated with extrahepatic disease progression in one patient. All patients died from neoplastic disease progression despite further chemotherapy at 6, 17 and 31 months following the diagnosis of NRH. One patient developed liver failure and ascites at the time of death.

CONCLUSIONS

Physicians should be aware of the potential occurrence and therapeutic impact of NRH in patients suffering from CRLM and treated by neoadjuvant 5FU-oxaliplatin-based chemotherapy before major liver surgery.

Phase I/II study of cetuximab dose-escalation in patients with metastatic colorectal cancer (mCRC) with no or slight skin reactions on cetuximab standard dose treatment (EVEREST): Pharmacokinetic (PK), Pharmacodynamic (PD) and efficacy data

4037

Background: Response to epidermal growth factor receptor (EGFR) inhibitor, cetuximab appears to correlate with the intensity of the associated skin reaction. This randomized study investigated cetuximab dose-escalation in patients (pts) with EGFR-expressing mCRC failing irinotecan-including therapy (I). Methods: Pts were randomized 22 days after starting cetuximab (400 mg/m2 initial dose then 250 mg/m2/week [w]) with I (180 mg/m2 q 2 w) if they had not experienced >grade (G) 1 skin reaction, any other >G 2 cetuximab-related adverse event and were tolerant to I. Randomization was to standard cetuximab dose (Arm A; 250 mg/m2/w) or dose-escalation (Arm B; cetuximab dose increased by 50 mg/m2 q 2 w, until >G 2 toxicity, tumor response or dose = 500 mg/m2). Pts not randomized (Arm C) continued on standard cetuximab dose. Primary endpoint was to compare in skin and tumor biopsies, taken before and during treatment, the effects of dose-escalation on EGFR and downstream signalling markers with those of the standard cetuximab regimen. Secondary endpoints were PK, efficacy, safety, tolerability, biomarker analyses on tumor biopsies and plasma samples. Results: 284 pts screened, 221 pts EGFR-expressing, 166 pts enrolled and randomized: 45 to Arm A; 44 to Arm B. 77 non-randomized pts were included in Arm C. M/F 106/60, median age 60 years [25–79], median KPS 90 [70–100]. 24 pts in Arm B reached 500 mg/m2/w. By the cut-off date of July 31st 2006 the preliminary response rate (RR) in Arm B was 30% vs. 13% in Arm A. RR in arm C was 22%. Preliminary progression-free survival in Arm A was 3,9 mo vs. 4,8 mo in Arm B and 3,9 mo in Arm C. In Arm B, 9% pts had G 3/4 skin reactions, 0% in Arm A (14% in Arm C). Dose related increases in Cmax and AUC were observed. T1/2 values were dose independent. Conclusions: Cetuximab dose- escalation up to 500 mg/m2/w improves RR in pts with no or slight skin reactions on standard dose treatment. Overall cetuximab PK behavior is in good agreement with previous experience. Treatment was generally well tolerated. PD and biomarker results will be presented at the meeting.

No significant financial relationships to disclose.

Patient-reported outcome (PRO)-assessed clinical benefit with panitumumab (Pmab) in metastatic colorectal cancer (mCRC) patients (pts)

6560

Background: In a phase III study of mCRC pts, Pmab monotherapy significantly improved partial response (PR) rates and progression-free survival (PFS) compared with best supportive care (BSC). This analysis characterizes the clinical benefit of PR/stable disease (SD) and PFS in mCRC pts with respect to health-related quality of life (HRQoL) and CRC symptoms. Methods: Pts had documented disease progression (DP) after treatment (tx) with fluoropyrimidine-, irinotecan-, and oxaliplatin- containing chemotherapy regimens. Pts were randomized 1:1 to receive BSC + Pmab 6mg/kg Q2W. HRQoL (EQ-5D and EORTC QLQ-C30 Global QoL subscale) and CRC symptoms (NCCN/FACT CRC symptom index, FCSI) were assessed at baseline, at least Q4W during tx, and at the 30 day safety follow-up visit. Only pts with PFS ≥ 56 days were included in the analysis to minimize potential lead-time bias associated with response evaluation. T-tests and least square estimates were calculated for differences in PRO measures at 4, 8, 12, 16, and 20 weeks controlling for baseline score by best response (PR or SD vs. other) and by tx arm. Imputation of missing data incorporated each pt's rate of change to assign missing values. Results: In the Pmab arm (n=231), 36% of pts had PR or SD; in the BSC arm (n=232) 10% of pts had SD (no PRs). 109 Pmab pts and 63 BSC pts had at least 1 post-baseline PRO assessment and a PFS time ≥ 56 days. In the Pmab arm, pts with a best response of PR or SD (n=73) had significantly higher mean HRQoL scores at all 5 time points (indicating better HRQoL) compared to those with a best response of < SD (n=36, p=0.03). Consistent results were observed between pts with a best response of PR/SD and CRC symptom scores (p=0.002), indicating less CRC symptomatology. However, in the BSC arm, pts with SD (n=20) had no significant differences in HRQoL or CRC symptoms at any time point compared to pts with < SD (n=43, p=0.12). Results were consistent across all instruments and imputation methods used. Conclusions: These findings show that among Pmab pts with PFS ≥ 56 days, those who had a best response of PR or SD experience significantly higher HRQoL and less CRC symptomatology than Pmab pts without a response. These data suggest that delaying DP may result in clinical benefit.

[Table: see text]