www.nature.com/bjc ARTICLE Clinical Study A phase 2 study of panitumumab with irinotecan as salvage therapy in chemorefractory KRAS exon 2 wild-type metastatic colorectal cancer patients Elena Elez1, Carles Pericay2, Manuel Valladares-Ayerbes3,16, Inmaculada Bando4,5, Maria Jose Safont6, Javier Gallego7, Cristina Grávalos8, Antonio Arrivi9,17, Alfredo Carrato10, Verónica Conde11, Maria José Ortiz12, Carlos López13, Beatriz Alonso14, Inmaculada Ruiz de Mena15, Eduardo Díaz-Rubio4,5, Josep Tabernero1 and Enrique Aranda12 BACKGROUND: Targeted agents are standard treatment for RAS wild-type metastatic colorectal cancer in the first- and second-line settings. This phase 2 study determined the benefit of targeting the epidermal growth factor receptor (EGFR) with panitumumab plus irinotecan in irinotecan-refractory patients. METHODS: KRAS exon-2 wild-type patients failing prior irinotecan received panitumumab (6 mg/kg) and irinotecan (180 mg/m²) every 2 weeks. The primary endpoint was the overall response rate (ORR). Secondary endpoints included safety, progression-free survival (PFS) and overall survival (OS). KRAS exon-2 status was evaluated centrally, along with NRAS, BRAF mutations, epiregulin, amphiregulin, PTEN and EGFR copy number status, and correlated with efficacy. RESULTS: Sixty-one patients were treated. Among the 46 wild-type RAS patients, the ORR was 15.2% (seven partial responses), with median PFS of 3.8 months (95% CI 2.7–4.3) and median OS of 12.5 months (95% CI 6.7–15.9). Wild-type BRAF patients showed a 13.0% response rate. No significant correlations between response and baseline biomarker expression were identified. Common grade 3–4 adverse events were diarrhoea and rash (18.0% each), hypomagnesaemia and asthenia (8.2% each). CONCLUSIONS: The addition of panitumumab to irinotecan as salvage therapy is feasible but has limited activity in irinotecan- refractory metastatic colorectal cancer. No biomarkers predictive of response were identified. British Journal of Cancer (2019) 121:378–383; https://doi.org/10.1038/s41416-019-0537-z BACKGROUND to single-agent irinotecan after fluoropyrimidine-based ther- Therapeutic management of colorectal cancer (CRC) has changed apy.2 Subsequently, two large phase 3 studies demonstrated dramatically over the last few decades with the addition firstly of that the addition of panitumumab to irinotecan as monotherapy oxaliplatin and irinotecan to the chemotherapeutic mainstay of or FOLFIRI in wild-type Kirsten rat sarcoma viral (KRAS) patients fluoropyrimidine with leucovorin, and then subsequently with the failing fluoropyrimidine-based therapy improved progression- use of targeted biological therapies including anti-epidermal free survival (PFS) and response rate, although without a growth factor receptor (EGFR) and anti-angiogenic agents, both of significant impact on overall survival (OS).3,4 The success of which have considerably improved survival outcomes. By con- blocking EGFR signalling is dependent on KRAS mutational sequence, the metastatic chemorefractory setting currently status, with the efficacy benefits of cetuximab treatment in accounts for ~50% of all CRC patients,1 and better salvage therapy metastatic CRC (mCRC) patients being confined to tumours wild- options are needed for this population. type for KRAS codons 12 and 13, while RAS mutations predict Among EGFR-targeted therapies, the monoclonal antibodies adverse outcomes with panitumumab-FOLFOX treatment.5,6 cetuximab and panitumumab both block EGF and TGFα Furthermore, benefit with anti-EGFR antibodies in combination signalling. Cetuximab was the first to show benefit when added with chemotherapy as front-line therapy in patients with RAS 1 Department of Medical Oncology, Vall d’Hebron Institute of Oncology, Hospital Universitari Vall d’Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain; 2Department of Medical Oncology, C.S. Parc Tauli, Barcelona, Spain; 3Department of Medical Oncology, Complejo Hospitalario Universitario A Coruña, A Coruña, Spain; 4Laboratory Hospital Clínico San Carlos. Instituto de Investigación Hospital Clínico San Carlos (IdISSC), University Complutense, Madrid, Spain; 5CIBERONC, Madrid, Spain; 6Department of Medical Oncology, General Universitario de Valencia Hospital, Valencia, Spain; 7Department of Medical Oncology, General Universitario de Elche Hospital, Alicante, Spain; 8Department of Medical Oncology, Universitario Doce de Octubre Hospital, Madrid, Spain; 9Department of Medical Oncology, Son Llàtzer Hospital, Palma de Mallorca, Spain; 10Department of Medical Oncology, IRYCIS, CIBERONC, Alcalá University, Hospital Universitario Ramón y Cajal, Madrid, Spain; 11Department of Medical Oncology, Virgen de las Nieves Hospital, Granada, Spain; 12IMIBIC, Reina Sofía Hospital, University of Córdoba, CIBERONC, Instituto de Salud Carlos III, Córdoba, Spain; 13Department of Medical Oncology, Marqués de Valdecilla Hospital, Santander, Spain; 14Department of Medical Oncology, Universitario de Canarias Hospital, Tenerife, Spain and 15Spanish Cooperative Group for the Treatment of Digestive Tumours (TTD), Madrid, Spain Correspondence: Josep Tabernero (jtabernero@vhio.net) 16 Present address: IMIBIC, Reina Sofía Hospital, University of Córdoba, CIBERONC, Instituto de Salud Carlos III, Córdoba, Spain 17 Present address: Clínica Rotger, Palma, Balearic Islands, Spain Received: 7 December 2018 Accepted: 11 July 2019 Published online: 31 July 2019 © The Author(s) 2019 Published by Springer Nature on behalf of Cancer Research UK A phase 2 study of panitumumab with irinotecan as salvage therapy in. . . E Elez et al. 379 wild-type mCRC, is greatest in patients with left-sided tumours,7 Biomarker analysis with similar effects in later lines.8,9 Tumour blocks were reviewed centrally. DNA and RNA were Few options exist for patients with irinotecan-refractory extracted using QIAamp® DNA FFPE Tissue and RNeasy® FFPE kits mCRC. Over a decade ago, the pivotal BOND study demon- and analysed with a Nanodrop® ND1000. Mutations in KRAS strated that the addition of EGFR-targeted cetuximab to codons 61, 117 and 146, and NRAS codons 12, 13, 61, 117 and 146 irinotecan restored chemotherapy sensitivity in a patient were detected by pyrosequencing. Mutations in BRAF (V600E) and population previously treated with irinotecan, most of whom PIK3CA (R88Q, N345k, C420R, E542K, E545D, E545K, M1043I, had received at least two prior therapy lines.10 A significantly H1047R and H1047Y) were detected by real-time PCR cobas® higher response rate was seen for the combination (22.9% Mutation Tests. Amphiregulin and epiregulin mRNA expression was versus 10.8% with irinotecan alone, p = 0.007), along with evaluated by real-time PCR with TaqMan® Gene Expression assays. improved PFS (4.1 versus 1.5 months, respectively; hazard ratio ROC curves were used to determine cut-off values for high versus 0.54 [95% CI, 0.42–0.71], p < 0.001). low expression. PTEN protein expression was assessed with the 17. In the current study, we report the results of a single-arm phase A mouse monoclonal antibody. PTEN-negative was defined as 2 study evaluating the effect on efficacy of the addition of no or weak staining and positive as moderate or strong. EGFR panitumumab to irinotecan as salvage therapy in wild-type KRAS was analysed by fluorescence in situ hybridisation by two exon-2 mCRC patients progressing on irinotecan-based therapy. blinded pathologists using an EGFR-specific probe (orange signal) Efficacy was analysed in terms of response rate, PFS and OS, along and a control chromosome probe 7 (green signal); two orange with evaluation of patient characteristics and genetic alterations and green signals per tumour cell or a ratio ≤1 was considered as potential biomarkers predictive of benefit. to be no EGFR amplification, more than two orange and green signals with a ratio greater than 2 or a ratio of 1.5 in ≥10% cells was considered amplification, four orange and METHODS green signals in ≥10% tumour cells was polysomy. See also Patients Supplementary Methods. Adult patients aged ≥18 years with histologically-confirmed metastatic adenocarcinoma of the colon or rectum and wild- Statistical analysis 1234567890();,: type KRAS (codons 12 and 13; allelic discrimination, investigator- A two-stage Simon model was used to test the null hypothesis evaluated) were eligible. Patients had to have progressed (by that P0 ≤ 0.1512 versus true activity with P1 ≥30%, and assuming radiographic imaging) during or within 3 months after irinotecan- α = 0.1 and β = 0.1. Accordingly, if responses were seen in at least based therapy, either 180 mg/m² every 2 weeks (single-agent or six of the first 34 evaluable patients, a further 19 evaluable FOLFIRI) or 350 mg/m² every 3 weeks (single-agent), and have patients were included. If overall, at least 16 patients achieved an received irinotecan for at least 6 weeks, with no more than two objective response, the combination was considered sufficiently dose reductions. In addition, one or more measurable lesion, a active. Sixty wild-type KRAS patients were planned, allowing for a Karnofsky performance status of at least 70%, adequate haema- 10% non-evaluable rate. tological, hepatic and renal function, and serum magnesium and The primary endpoint was the overall response rate (ORR) in the calcium levels within normal limits were required. Prior anti-EGFR intention-to-treat (ITT) population. Secondary endpoints included therapy was not permitted. Patients provided written informed disease control rate, PFS, OS, and safety. PFS and OS were consent prior to enrolment. analysed by the Kaplan–Meier method. Efficacy was also analysed in terms of candidate predictive molecular markers (RAS, BRAF, Study design PI3K and PTEN mutations, EGFR amplification, PTEN loss-of- This phase 2 single-arm, open-label study was performed in 12 function, and epiregulin and amphiregulin levels) using log-rank Spanish centres. Patients received panitumumab (6 mg/kg, 60-min tests, and baseline patient and disease covariates using logistic infusion) followed by irinotecan (180 mg/m², 90-min infusion) regression with univariate and multivariate proportional hazard every 2 weeks. For patients who had received a reduced dose with models. Analyses were performed with SAS version 9.4. prior irinotecan therapy, this dose was maintained, and for patients who had received 350 mg/m² irinotecan every 3 weeks, the equivalent every-2-weeks dose was used. In the event of grade RESULTS 3–4 related events or skin or nail toxicity requiring treatment or A total of 61 patients with KRAS exon 2 wild-type CRC tumours considered intolerable, panitumumab was withheld and the dose were enrolled between July 2009 and June 2012 and received a reduced (to 4.8 then 3.2 mg/kg), while irinotecan was maintained. median of 78 days of treatment (range, 1–279). Patient demo- If irinotecan was delayed, panitumumab was also delayed graphics and disease characteristics are shown in Table 1. All (maximum of 1 month). Panitumumab monotherapy was per- patients had received one or two prior lines of treatment for mitted after irinotecan discontinuation but not vice versa. Patients metastatic disease, all of whom had received prior irinotecan, 92% who underwent curative metastatic resection could continue in of patients had received prior oxaliplatin and 62% had been the study 4 weeks later. Patients continued treatment until treated with at least one prior line of bevacizumab. Extended RAS progression or unacceptable toxicity. analysis was performed in 57 patients, 46 of whom were confirmed to be wild-type. Efficacy and safety assessments Tumour response was evaluated by computerised tomography Anti-tumour activity scan and/or magnetic resonance imaging according to the At the cut-off date of 27 February 2014, median follow-up was modified Response Evaluation Criteria in Solid Tumours (m- 11 months (95% CI 6.7–14.8). In the overall population, eight RECIST).11 Response was assessed every 6 weeks during the first patients had partial responses giving an ORR of 13.1% (95% CI, 6 months and every 2 months thereafter until progression or 4.6– 21.6%) in the 61 ITT patients (Table 2). The disease control rate withdrawal. Responses were confirmed at least 1 month after was 62.3% (95% CI, 50.1–74.5%), including 30 patients with stable the criteria were first met. After discontinuation, patients disease, lasting a median of 3.0 months (95% CI, 2.1–3.4 months). without progression were followed-up every 6 weeks until Median PFS was 3.7 months (95% CI, 2.7–4.2 months) and median progression, and progressing patients were followed-up every OS was 11.1 months (95% CI, 7.1–14.8 months). None of the 3 months. Adverse events (AEs) were graded according to NCI- candidate predictive factors evaluated by regression analysis (sex, CTCAE v3.0. performance status, age, number of previous lines of therapy, A phase 2 study of panitumumab with irinotecan as salvage therapy in. . . E Elez et al. 380 tumour location, lactate dehydrogenase levels) affected survival Table 1. Patient, tumour and treatment characteristics, ITT population parameters or the response rate. N = 61 Efficacy was also analysed among the 46 RAS wild-type patients, seven of whom had partial response versus 1 of the 11 RAS- Age, in years mutated patients, giving ORRs of 15.2% (Table 2) versus 9.1%, in Median (range) 65 (40–81) these two populations, respectively. Disease control in the wild- >70 years, N (%) 20 (32.8%) type population was 67.4% (95% CI, 53.8–80.4%). This translated into only small differences in survival, with a median PFS in wild- Males, N (%) 40 (65.6%) type patients of 3.8 months (95% CI, 2.7–4.3 months) versus Primary tumour, N (%) 2.9 months (95% CI, 1.4–4.6 months) in RAS-mutated patients Colon 43 (70.5%) (Fig. 1). Median OS was 12.5 months (95% CI, 6.7–15.9 months) in Rectum 18 (29.5%) wild-type patients versus 11.1 months (95% CI, 4.2–23.9 months) Median time since diagnosis in months, (range) 30 (3–130) in mutated patients. Efficacy was further analysed in this sub- population according to prior bevacizumab treatment, showing TNM stage, N (%)a similar trends to the overall wild-type population (Table 2). II 5 (8.2%) Although ORR was improved in patients who had received prior III 9 (14.8%) bevacizumab compared to those who had not (20.7% vs 5.9%, IVA-B 43 (7.5%) respectively), this did not translate into any obvious differences in Histology grade, N (%)b terms of disease control (69.0% vs 64.7%, respectively) or median PFS (3.8 vs 3.9 months, respectively). 1 11 (18.0%) Efficacy was also analysed according to several candidate 2 35 (57.4%) predictive biomarkers, comparing subpopulations with and with- 3 9 (14.8%) out mutations or amplifications in key molecular pathways (BRAF, Wild-type RAS, N (%)c 46 (80.7%) PI3KCA, PTEN and EGFR) and with high versus low expression Metastatic locations, N (%) (amphiregulin and epiregulin). No significant associations between the presence of these biomarkers and response were found, Liver 44 (72.1%) although analyses suggested some minor trends towards Lung 35 (57.4%) improved efficacy in patients with wild-type BRAF, wild-type Lymph nodes 18 (29.5%) PI3KCA, high epiregulin or amphiregulin expression and/or without Peritoneum 8 (13.1%) EGFR amplification. Other 17 (27.9%) Among the 54 patients with wild-type BRAF status, seven had a partial response, giving a response rate of 13.0% versus 25.0% in Prior palliative therapy, N (%) mutated patients (one response among four patients). PFS was N lines 3.7 months (95% CI, 2.7–4.2) versus 1.8 months (95% CI, 0.7–6.4), 1 61 (100%) respectively. Analysis of the all-RAS/all-BRAF wild-type population 2 43 (70.5%) gave similar outcomes to each of the individual contributing wild- ≥3 11 (18.0%) type populations with an ORR of 14.3%, disease control of 71.4% (95% CI 57.8–85.1%) and median PFS of 4.0 months (95% CI, Oxaliplatin 56 (92.0%) 2.7–4.6 months). Of the 49 wild-type PI3KCA patients, seven had Bevacizumab 38 (6.02%) partial response, giving a response rate of 14.3% versus 12.5% in Prior adjuvant therapy, N (%) 24 (39.3%) mutated tumours. PFS was 3.9 months (95% CI, 2.9–4.3) versus Prior surgery, N (%) 50 (82.0%) 2.7 months (95% CI, 0.7–5.7) respectively. a Epiregulin was analysed in 35 patients; partial responses were Missing data for four patients seen in three of the 18 high expression patients and two of the 17 b Missing data for six patients c low expression patients, giving 16.7% and 11.8% response rates, Extended RAS analysis was performed in 57 patients respectively. Median PFS was 3.9 months (95% CI, 2.7–4.6) and Table 2. Tumour response (m-RECIST) and survival, ITT patients All patients N = 61 Wild-type RAS N = 46 Wild-type RAS with prior bevacizumab N = 29 Objective response, N (%) Partial response 8 (13.1%) 7 (15.2%) 6 (20.7%) Stable disease 30 (49.2%) 24 (52.2%) 14 (48.3%) Progressive disease 17 (27.9%) 12 (26.1%) 8 (27.6%) Not evaluable/not done 6 (9.8%) 3 (6.5%) 1 (3.5%) Overall response rate [95% CI] 13.1% [4.6–21.6%] 15.2% [4.8–25.6%] 20.7% [6.0–35.4%] Disease control, N (%) [95% CI] 38 (62.3%) [50.1–74.5%] 31 (67.4%) [53.8–80.4%] 20 (69.0%) [52.1–85.8%] PFS (months) Median [95% CI] 3.7 [2.7–4.2] 3.8 [2.7–4.3] 3.8 [2.4–4.6] N events/censored 60/1 45/1 29/0 OS (months) Median [95% CI] 11.1 [7.1–14.8] 12.5 [6.7–15.9] 14.8 [6.7–16.7] N events/censored 56/5 42/4 28/1 A phase 2 study of panitumumab with irinotecan as salvage therapy in. . . E Elez et al. 381 100 Table 3. Main treatment-related adverse events (NCI-CTCAE) (N = 61) Median (95%Cl) Mutated 2.9 months (1.4 – 4.6) Grade 1–4 Grade 3 Grade 4 80 Wild type 3.8 months (2.7 – 4.3) Diarrhoea 38 (62.3%) 9 (14.8%) 2 (3.3%) Rash 36 (59.0%) 11 (18.0%) 60 Asthenia 31 (50.8%) 5 (8.2%) Percent Hypomagnesaemia 27 (44.3%) 3 (4.9%) 2 (3.3%) 40 Mucosal inflammation 18 (29.5%) Dry skin 16 (26.2%) 2 (3.3%) Vomiting 16 (26.2%) 20 Nausea 15 (24.6%) Paronychia 13 (21.3%) 1 (1.6%) 0 Alopecia 12 (19.7%) 1 (1.6%) 0 1 2 3 4 5 6 7 8 9 Acne 11 (18.0%) Time (months) Neutropenia 9 (14.8%) 2 (3.3%) 2 (3.3%) Fig. 1 Progression-free survival in RAS wild-type and mutated ITT Decreased appetite 7 (11.5%) 1 (1.6%) patients, by Kaplan–Meier estimate Anaemia 6 (9.8%) 1 (1.6%) Erythema 6 (9.8%) Abdominal pain 5 (8.2%) 1 (1.6%) 2.9 months (95% CI, 1.4–4.8), respectively. Among the 35 patients Conjunctivitis 5 (8.2%) 1 (1.6%) evaluated for amphiregulin, four partial responses were seen in Hypokalaemia 4 (6.6%) 1 (1.6%) the 18 high expression patients and 1 of the 17 patients with low expression, giving response rates of 22.2% and 5.9%, respectively. Gastrointestinal toxicity 3 (4.9%) 1 (1.6%) Median PFS was 4.3 months (95% CI, 3.0–5.4) and 2.7 months (95% Back pain 2 (3.3%) 1 (1.6%) CI, 1.4–3.6), respectively. Keratitis 1 (1.6%) 1 (1.6%) Among the 32 patients evaluable for PTEN, none of the nine Acute respiratory distress 1 (1.6%) 1 (1.6%) patients expressing PTEN responded, while five non-expressing Bacterial infection 1 (1.6%) 1 (1.6%) patients had a partial response (21.7%). Median PFS was 4.1 months (95% CI, 0.7–4.9) in patients with PTEN and 3.0 months Dermatitis acneiform 1 (1.6%) 1 (1.6%) (95% CI, 1.6–4.1) in patients without. Among the 34 patients Intestinal obstruction 1 (1.6%) 1 (1.6%) evaluable for EGFR amplification status, three patients showed Infusion reaction 1 (1.6%) 1 (1.6%) amplification, all of whom had presented stable disease, Toxic skin eruption 1 (1.6%) 1 (1.6%) compared with five partial responses among the 31 EGFR-negative patients (16.1%). PFS was 2.9 months (95% CI, 2.7–3.6) versus 3.7 months (95% CI, 1.6–4.6). Safety 3.8 months in our study).13 This response rate was also slightly As anticipated, the most common treatment-related AEs were lower than that reported in an equivalent approach and setting in gastrointestinal and dermatological, including diarrhoea a phase 2 Japanese study, TOPIC, in which the response rate was (62.3%), rash (59.0%), asthenia (50.8%), hypomagnesaemia 23%,14 and was also lower than the 26% rate reported in a (44.3%), mucosal inflammation (29.5%), vomiting (26.2%) and preliminary evaluation of another phase 2 randomised Japanese nausea (24.6%) (Table 3). Dry skin, paronychia and acne were study, WJOG6510G, comparing this EGFR combination with the reported in 26.2%, 21.3% and 18.0% of patients, respectively. equivalent cetuximab combination.15 Median PFS and OS in our The profile of grade 3–4 related AEs was similar with lower study (3.8 and 12.5 months, respectively) were also shorter than frequency, including diarrhoea and rash (18.0%), and hypomag- those reported in the WJOG6510G study (5.4 and 14.9 months, nesaemia and asthenia (8.2% each). One patient died as a result respectively), but in contrast were improved compared to the of sepsis considered related to irinotecan, with concurrent TOPIC study (2.7 and 7.3 months, respectively). Differences in pneumonia and grade 4 febrile neutropenia. Eleven patients irinotecan regimens may have influenced response rates in each (18.0%) had a related AE leading to treatment discontinuation, of these studies, as suggested from analyses performed in the five patients stopped panitumumab and six patients stopped TOPIC study. irinotecan due to related toxicity. The 15% response rate with the combination therapy is also lower than the 22% rate reported for single-agent panitumumab in the phase 3 ASPECCT study in a comparison with single-agent DISCUSSION cetuximab in chemotherapy-refractory wild-type KRAS exon 2 In this single-arm combination study, the addition of panitumu- mCRC patients,16 although more patients in our study had mab to irinotecan in irinotecan-refractory wild-type KRAS exon-2 received prior bevacizumab. Median PFS and OS in our study mCRC patients gave a 15% response rate. This falls well short of were similar to those reported in the ASPECCT study (4.1 and the protocol’s statistical hypothesis threshold of 30% (reflecting 16 10.4 months, respectively), as well as to those reported in KRAS responses out of 53 patients), which was considered to wild-type patients treated with panitumumab and best supportive demonstrate an efficacy benefit. It is also notably lower than the care in a phase 3 study (response rate 27%, median PFS 35% response rate reported in heavily pre-treated patients 3.8 months, median OS 10.0 months).17 In light of all these harbouring wild-type KRAS (codon 12 and 13) treated with studies, our results suggest that the addition of panitumumab to panitumumab and irinotecan in the one-arm phase 2 French irinotecan as salvage therapy did not offer a meaningful efficacy GERCOR study, as was PFS (6.3 months in the GERCOR versus advantage in the setting of our study. A phase 2 study of panitumumab with irinotecan as salvage therapy in. . . E Elez et al. 382 It is important to bear in mind that since 2015, recommenda- Nonetheless, the value of the panitumumab/irinotecan combina- tions for treatment of mCRC patients have included that EGFR tion over single-agent panitumumab appears limited. inhibitors should not be administered in cases of NRAS-mutated tumours.18 However as this had not yet been formally implemen- ted at the time of patient accrual during the current study ACKNOWLEDGEMENTS (2009–2012), NRAS-mutated patients were included and treated. The authors thank the following physicians for their cooperation and support: Study The absence of biomarkers for response other than KRAS, is a Chairs: J. Tabernero (Vall d’Hebron University Hospital, Barcelona) and E. Aranda. pressing issue that needs to be resolved in order to move ahead Practicing physicians included J. Tabernero and E. Elez (Vall d’Hebron University Hospital, Barcelona), C. Pericay (C. S. Parc Tauli, Barcelona), M. Valladares-Ayerbes with the approach of optimising the choice of therapy, and to (Complejo Hospitalario Universitario La Coruña, La Coruña), M.J. Safont (General ensure avoiding unnecessary drug exposure and to overcome Universitario de Valencia Hospital, Valencia), J. Gallego (General Universitario de Elche resistance developing after treatment with targeted therapies. The Hospital, Alicante), C. Grávalos (12 de Octubre Hospital, Madrid), A. Arrivi (Son Llatzer recent phase 2 randomised AGITG ICECREAM trial evaluated the Hospital. Palma de Mallorca), A. Carrato (Ramón y Cajal Hospital, Madrid), V. Conde addition of irinotecan to cetuximab in chemorefractory mCRC (Virgen de las Nieves Hospital, Granada), E. Aranda and M. J. Ortiz (Reina Sofía patients, and demonstrated a 36% response rate in patients who Hospital, University of Córdoba), F. Rivera and Carlos López (Marqués de Valdecilla were quadruple wild-type for KRAS, NRAS, BRAF and PI3KCA after Hospital, Santander), and B. Alonso (Universitario de Canarias Hospital, Tenerife). We treatment with irinotecan and cetuximab, and a 6-month PFS rate also thank the following groups who contributed to the study: the biomarker analysis of 41%.19 Accumulating evidence suggests that response to laboratory (E. Díaz-Rubio and T. Caldes, HCSC, Madrid), the TTD Data Centre (Inmaculada Ruiz de Mena and Susana Rodriguez), monitoring, statistics and data panitumumab in advanced CRC correlates with wild-type BRAF,20 management (Lucía Monar and Elisabet Molina at TFS Trial Form Support, Spain). EFGR copy number,21 epiregulin and amphiregulin levels,22 while Amgen provided support for third-party writing assistance for this manuscript, BRAF, NRAS and PIK3CA mutations and non-functional PTEN have furnished by Sarah MacKenzie PhD. all been associated with resistance to anti-EGFR therapies.23 Although minor non-significant trends in this study suggested a greater benefit in patients with wild-type BRAF, wild-type PI3KCA, AUTHOR CONTRIBUTIONS high epiregulin or amphiregulin expression and/or without EGFR Study conception: J.T. and E.A.; Study design: J.T. and E.A.; Data acquisition: All amplification, none of the members of the RAS/RAF/ERK and PI3K/ authors; Data analysis and interpretation: J.T., E.E. and E.A.; Manuscript preparation: J. PTEN pathways were definitively identified as potential predictive T., E.E. and E.A.; Manuscript editing: J.T., E.E. and E.A.; Manuscript review: All authors. biomarkers. Nonetheless the French GERCOR study argues for the value of salvage panitumumab with irinotecan in patients wild- type for multiple EGFR markers, in light of the 46% response rate ADDITIONAL INFORMATION and the median PFS of 8.7 months seen in patients without Supplementary information is available for this paper at https://doi.org/10.1038/ mutations in any of the rare KRAS, NRAS and BRAF genes, while no s41416-019-0537-z. responses were seen in patients with confirmed mutations.13 Competing interests: M.V.A. has received payment for advisory roles from Amgen, At the time this study was launched, none of the salvage Merck and Sanofi, honoraria from Bayer, Servier and Roche, payment for research therapies used were considered standard of care in mCRC patients funding from Roche and other remuneration from Roche, Merck and Amgen. V.C. has who had failed the classic chemotherapeutic treatments of received honoraria from Amgen. A.C. has received honoraria for advisory roles from fluoropyrimidine, irinotecan and oxaliplatin in combination with Bayer, Shire and Celgene. E.A. has received honoraria for advisory roles from Amgen, targeted therapies. In the most recent consensus guidelines for Bayer, Celgene, Merck, Roche, Sanofi. E.E. has a scientific consultancy role for Array managing mCRC,1,24 cetuximab combined with irinotecan is Biopharma, Merck Serono, F. Hoffmann-La Roche Ltd, Sanofi, Servier, Amgen. J.T. has recommended in irinotecan-refractory patients. The multi- scientific consultancy role for Array Biopharma, AstraZeneca, Bayer, BeiGene, targeted kinase inhibitor regorafenib has recently been approved Boehringer Ingelheim, Chugai, Genentech, Inc., Genmab A/S, Halozyme, Imugene for salvage therapy given the significant survival advantage seen Limited, Inflection Biosciences Limited, Ipsen, Kura Oncology, Lilly, MSD, Menarini, Merck Serono, Merrimack, Merus, Molecular Partners, Novartis, Peptomyc, Pfizer, over best supportive care.25 Similarly, the trifluridine/tipiracil Pharmacyclics, ProteoDesign SL, Rafael Pharmaceuticals, F. Hoffmann-La Roche Ltd, combination is also recommended in the salvage setting, Sanofi, SeaGen, Seattle Genetics, Servier, Symphogen, Taiho, VCN Biosciences, following results suggesting a similar benefit with less toxicity.26 Biocartis, Foundation Medicine, HalioDX SAS and Roche Diagnostics. E.D.R. has The toxicity profile of the combination was as expected, with received honoraria for advisory roles or speaker from Roche, Merck Serono, Amgen, effects similar to those reported previously for panitumumab Bayer, MSD, Genomica and research funding from Roche, Merck-Serono, Amgen, addition to irinotecan3,4,13,14 as well as that reported in the BOND Astra Zeneca. C.L. has received honoraria from, performed consultancy for and/or study when cetuximab was co-administered with irinotecan in this received research funding from Roche, Merc, Sanofi, Novartis, Pfizer, Eisai, Ipsen, setting.10 Dermatological toxicity frequently associated with EGFR Bayer, AstraZeneca, Servier, Amgen, Bayer, MSD and Celgene. The remaining authors blockade was prevalent, but was generally well managed with declare no competing interests. dose modifications. It should be acknowledged that the use of a single-arm design Ethics approval and consent to participate: This study was approved by the local and the relatively small sample size (and small number of ethics committee (the independent ethics committee of hospital Universitari Vall responses) limit interpretation of the current study, notably in d’Hebrón, as the Clinical Research Ethics Committee Coordinating Center) and the terms of identification of predictive and pharmacodynamic Spanish Health Authorities and was conducted in accordance with the principles of biomarkers. Future studies in this setting should exploit the the Declaration of Helsinki. Patients were instructed about the experimental addition of other targeted therapies to panitumumab. The use of procedures of the study and enrolled after signature of the informed consent. circulating cell-free DNA in liquid biopsies is now widely considered a reliable method for determining KRAS and BRAF Funding: This work was supported by Amgen S.A, who did not have any role in study gene mutations in mCRC.27 Use of liquid biopsies is becoming design; collection, analysis and interpretation of data; writing the report, or the increasingly widespread, to facilitate routine and prospective decision to submit the report for publication. biomarker testing in clinical studies, and to overcome the difficulties associated with obtaining biopsies of adequate quality Data availability: Data and results are available at the Department of Medical or serial biopsies. Oncology, Vall d’Hebron Institute of Oncology, Universitat Autònoma de Barcelona, In conclusion, the addition of panitumumab to irinotecan was Barcelona, Spain. feasible as salvage therapy in a heavily pre-treated population of mCRC, in which most patients had received at least two prior lines Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims of therapy including the anti-angiogenic agent bevacizumab. in published maps and institutional affiliations. A phase 2 study of panitumumab with irinotecan as salvage therapy in. . . E Elez et al. 383 REFERENCES KRAS exon 2 metastatic colorectal cancer (ASPECCT): a randomised, multi- 1. Van Cutsem, E., Cervantes, A., Adam, R., Sobrero, A., Van Krieken, J. H. Aderka, D. centre, open-label, non-inferiority phase 3 study. Lancet Oncol. 15, 569–579 et al. ESMO consensus guidelines for the management of patients with meta- (2014). static colorectal cancer. Ann. Oncol. 27, 1386–1422 (2016). 17. Kim, T. 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Panitumumab combined with irinotecan for patients with KRAS wild-type metastatic colorectal cancer refractory to standard chemotherapy: a GERCOR Open Access This article is licensed under a Creative Commons efficacy, tolerance, and translational molecular study. Ann. Oncol. Esmo. 24, Attribution 4.0 International License, which permits use, sharing, 412–419 (2013). adaptation, distribution and reproduction in any medium or format, as long as you give 14. Nishi, T., Hamamoto, Y., Nagase, M., Denda, T., Yamaguchi, K. Amagai, K. et al. appropriate credit to the original author(s) and the source, provide a link to the Creative Phase II trial of panitumumab with irinotecan as salvage therapy for patients with Commons license, and indicate if changes were made. The images or other third party advanced or recurrent colorectal cancer (TOPIC study). Oncol. Lett. 11, 4049–4054 material in this article are included in the article’s Creative Commons license, unless (2016). indicated otherwise in a credit line to the material. If material is not included in the 15. Sugimoto, N., Sakai, D., Tamura, T., Hara, H., Nishina, T. Esaki, T. et al. Randomized article’s Creative Commons license and your intended use is not permitted by statutory phase II study of panitumumab (Pmab) + irinotecan (CPT-11) versus cetuximab regulation or exceeds the permitted use, you will need to obtain permission directly (Cmab) + CPT-11 in patients (pts) with KRAS wild-type (WT) metastatic colorectal from the copyright holder. To view a copy of this license, visit http://creativecommons. cancer (mCRC) after fluoropyrimidine (FU), CPT-11, and oxaliplatin (L-OHP) failure: org/licenses/by/4.0/. WJOG6510G (abstract). J. Clin. Oncol. 35, 661 (2017). 16. Price, T. J., Peeters, M., Kim, T. W., Li, J., Cascinu, S. Ruff, P. et al. 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