Prognostic and predictive impact of metastatic organ involvement on maintenance therapy in advanced metastatic colorectal cancer: Subgroup analysis of patients treated within the PanaMa trial (AIO KRK 0212).

Despite molecular selection, patients (pts) with RAS wildtype mCRC represent a heterogeneous population including diversity in metastatic spread. We investigated metastatic patterns for their prognostic and predictive impact on maintenance therapy with 5-fluorouracil/folinic acid ± panitumumab. The study population was stratified according to (1) number of involved metastatic sites (single vs multiple organ metastasis), liver-limited disease vs (2) liver metastasis plus one additional site, and (3) vs liver metastasis plus ≥two additional sites. Kaplan-Meier method and Cox regressions were used to correlate efficacy endpoints. Single organ metastasis was observed in 133 pts (53.6%) with 102 pts (41.1%) presenting with liver-limited disease, while multiple organ metastases were reported in 114 pts (46.0). Multiple compared to single organ metastases were associated with less favorable PFS (HR 1.48, 95% CI 1.13-1.93; P = .004) and OS (HR 1.37, 95% CI 0.98-1.93; P = .068) of maintenance therapy. While metastatic spread involving one additional extrahepatic site was not associated with clearly impaired survival compared to liver-limited disease, pts with liver metastasis plus ≥two additional sites demonstrated less favorable PFS (HR 1.92, 95% CI 1.30-2.83; P < .001), and OS (HR 2.38, 95% CI 1.51-3.76; P < .001) of maintenance therapy. Pmab-containing maintenance therapy appeared active in both pts with multiple (HR 0.58; 95% CI, 0.39-0.86; P = .006) as well as to a lesser numerical extent in pts with single organ metastasis (HR 0.83; 95% CI, 0.57-1.21; P = .332; Interaction P = .183). These data may support clinical decisions when EGFR-based maintenance therapy is considered.

Efficacy and Safety of Panitumumab in Patients With RAF/RAS-Wild-Type Glioblastoma: Results From the Drug Rediscovery Protocol.

BACKGROUND: The prognosis of malignant primary high-grade brain tumors, predominantly glioblastomas, is poor despite intensive multimodality treatment options. In more than 50% of patients with glioblastomas, potentially targetable mutations are present, including rearrangements, altered splicing, and/or focal amplifications of epidermal growth factor receptor (EGFR) by signaling through the RAF/RAS pathway. We studied whether treatment with the clinically available anti-EGFR monoclonal antibody panitumumab provides clinical benefit for patients with RAF/RAS-wild-type (wt) glioblastomas in the Drug Rediscovery Protocol (DRUP). METHODS: Patients with progression of treatment refractory RAF/RASwt glioblastoma were included for treatment with panitumumab in DRUP when measurable according to RANO criteria. The primary endpoints of this study are clinical benefit (CB: defined as confirmed objective response [OR] or stable disease [SD] ≥ 16 weeks) and safety. Patients were enrolled using a Simon-like 2-stage model, with 8 patients in stage 1 and up to 24 patients in stage 2 if at least 1 in 8 patients had CB in stage 1. RESULTS: Between 03-2018 and 02-2022, 24 evaluable patients were treated. CB was observed in 5 patients (21%), including 2 patients with partial response (8.3%) and 3 patients with SD ≥ 16 weeks (12.5%). After median follow-up of 15 months, median progression-free survival and overall survival were 1.7 months (95% CI 1.6-2.1 months) and 4.5 months (95% CI 2.9-8.6 months), respectively. No unexpected toxicities were observed. CONCLUSIONS: Panitumumab treatment provides limited CB in patients with recurrent RAF/RASwt glioblastoma precluding further development of this therapeutic strategy.

Risk Evaluation of Proton Pump Inhibitors for Panitumumab-Related Hypomagnesemia in Patients with Metastatic Colorectal Cancer.

Hypomagnesemia commonly occurs as a side effect of panitumumab treatment. In severe cases, temporary discontinuation or dose reduction of panitumumab may be necessary. Proton pump inhibitors (PPIs) are reportedly potential risk factors for hypomagnesemia. We conducted a multicenter study to assess the impact of PPIs on the risk of grade 3-4 hypomagnesemia in patients with metastatic colorectal cancer (mCRC) receiving panitumumab. We adjusted for potential bias using a propensity score-matched analysis and retrospectively reviewed the medical records of patients. Hypomagnesemia severity was graded according to the Common Terminology Criteria for Adverse Events, version 5.0. A total of 165 patients were enrolled in this study. The incidence of grade 3-4 hypomagnesemia was significantly higher in the PPI group than in the non-PPI group, both before (20.0% [30/60] vs. 8.0% [8/105], p = 0.026) and after propensity score matching (16.2% [6/37] vs. 0% [0/37], p = 0.025). In the propensity score-matched cohort, the risk of grade 3-4 hypomagnesemia was significantly higher in the PPI group (odds ratio, 2.19; 95% confidence interval, 1.69-2.84; p = 0.025). These findings suggest that concomitant use of PPIs significantly increases the risk of grade 3-4 hypomagnesemia in patients with mCRC receiving panitumumab. Therefore, close monitoring of these patients is imperative.

Panitumumab plus trifluridine/tipiracil as anti-EGFR rechallenge therapy in patients with refractory RAS wild-type metastatic colorectal cancer: Overall survival and subgroup analysis of the randomized phase II VELO trial.

The randomized phase II VELO trial showed that the addition of panitumumab to trifluridine/tipiracil significantly improves progression-free survival (PFS) as compared to trifluridine/tipiracil in third-line therapy in patients with refractory RAS wild-type (WT) metastatic colorectal cancer (mCRC). With longer follow-up, final overall survival results and posttreatment subgroup analysis are presented. Sixty-two patients with refractory RAS WT mCRC were randomly assigned to receive, as third-line therapy, trifluridine/tipiracil alone (arm A) or in combination with panitumumab (arm B). Primary endpoint was PFS; secondary endpoints included overall survival (OS) and overall response rate (ORR). Median OS was 13.1 months (95% CI 9.5-16.7) in arm A compared to 11.6 months (95% CI 6.3-17.0) in arm B (HR: 0.96, 95% CI 0.54-1.71, P = .9). To evaluate the impact of subsequent lines of treatment, subgroup analysis was performed for the 24/30 patients in arm A, that received fourth-line therapy after disease progression. Median PFS was 4.1 months (95% CI 1.44-6.83) for 17 patients treated with anti-EGFR rechallenge as compared to 3.0 months (95% CI 1.61-4.31) for seven patients that received other therapies (HR: 0.29, 95% CI 0.10-0.85, P = .024). Median OS from the start of fourth-line treatment was 13.6 months (95% CI 7.2-20), and 5.1 months (95% CI 1.8-8.3) for patients treated with anti-EGFR rechallenge vs other therapies, respectively (HR: 0.30, 95% CI 0.11-0.81, P = .019). Final results of the VELO trial support the role of anti-EGFR rechallenge in the continuum of care of patients with RAS/BRAF WT mCRC.

The Phase II Study of Panitumumab in Chemotherapy-Naïve Frail or Elderly Patients with RAS Wild-type Colorectal Cancer: OGSG 1602 Final Results.

BACKGROUND: We previously reported the response rate of a phase II OGSG1602 study on panitumumab in chemotherapy-naive frail or elderly patients with RAS wild-type unresectable colorectal cancer (CRC) [Terazawa T, Kato T, Goto M, et al. Oncologist. 2021;26(1):17]. Herein, we report a survival analysis. METHODS: Patients aged ≥65 years and considered unsuitable for intensive chemotherapy or aged ≥76 years were enrolled. Primary tumors located from the cecum to the transverse colon were considered right-sided tumors (RSTs); those located from the splenic flexure to the rectum were considered left-sided tumors (LSTs). RESULTS: Among the 36 enrolled patients, 34 were included in the efficacy analysis, with 26 and 8 having LSTs and RSTs, respectively. The median progression-free survival (PFS) and overall survival (OS) were 6.0 [95% CI, 5.4-10.0] and 17.5 months (95% CI, 13.8-24.3), respectively. Although no significant differences existed in PFS between patients with LST and RST {6.6 (95% CI, 5.4-11.5) vs. 4.9 months [95% CI, 1.9-not available (NA), P = .120]}, there were significant differences in OS [19.3 (95% CI, 14.2-NA) vs.12.3 months (95% CI, 9.9-NA), P = .043]. CONCLUSION: Panitumumab showed favorable OS in frail or elderly patients with RAS wild-type CRC and no prior exposure to chemotherapy. Panitumumab may be optimal for patients with LSTs (UMIN Clinical Trials Registry Number UMIN000024528).

Phase Ib/II Study of the Efficacy and Safety of Binimetinib (MEK162) Plus Panitumumab for Mutant or Wild-Type RAS Metastatic Colorectal Cancer.

INTRODUCTION: Activating RAS gene mutations occur in approximately 55% of patients with metastatic colorectal cancer (mCRC) and are associated with poorer clinical outcomes due to epidermal growth factor receptor (EGFR) blockade resistance. Combined EGFR and mitogen-activated protein kinase (MEK) inhibition may extend response to EGFR inhibition and overcome acquired resistance. This phase Ib/II dose escalation trial evaluated the safety and activity of dual inhibition with binimetinib (MEK1/2 inhibitor) and panitumumab (EGFR inhibitor [EGFRi]) in patients with RAS mutant or BRAF wild type (WT)/RAS WT mCRC. METHODS: Phase Ib dose escalation started with binimetinib 45 mg twice daily plus panitumumab 6 mg/kg administered every 2 weeks. In the phase II study, patients with measurable mCRC were enrolled into 4 groups based on previous anti-EGFR monoclonal antibody therapy and RAS mutational status. RESULTS: No patients in the phase Ib portion (n = 10) had a response; 70% of patients had stable disease. In the phase II portion (n = 43), overall response rate (ORR, confirmed) was 2.3% with one partial response in the RAS WT group, DCR was 30.2%, and median progression-free survival was 1.8 months (95%CI, 1.6-3.3). All patients experienced ≥1 adverse event, with the most common being diarrhea (71.7%), vomiting (52.8%), nausea (50.9%), fatigue (49.1%), dermatitis acneiform (43.4%), and rash (41.5%). Most patients required treatment interruption or dose reduction due to difficulties tolerating treatment. CONCLUSIONS: The combination of binimetinib and panitumumab had substantial toxicity and limited clinical activity for patients with mutant or WT RAS mCRC, independent of EGFRi treatment history (Trial registration: NCT01927341).

Adjuvant Auger Electron-Emitting Radioimmunotherapy with [111In]In-DOTA-Panitumumab in a Mouse Model of Local Recurrence and Metastatic Progression of Human Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) has a high risk for recurrence and metastasis. We studied the effectiveness of Auger electron (AE) radioimmunotherapy (RIT) with antiepidermal growth factor receptor (EGFR) panitumumab conjugated with DOTA complexed to 111In ([111In]In-DOTA-panitumumab) for preventing metastatic progression after local treatment of 231/LM2-4 Luc+ human TNBC tumors in the mammary fat pad of NRG mice. Prior to RIT, the primary tumor was resected, and tumor margins were treated with X-irradiation (XRT; 5 days × 6 Gy/d). RIT was administered 1 day post-XRT by intravenous injection of 26 MBq (15 µg) or 2 × 10 MBq (15 µg each) separated by 7 d. These treatments were compared to tumor resection with or without XRT combined with DOTA-panitumumab (15 µg) or irrelevant [111In]In-DOTA-IgG2 (24 MBq; 15 µg), and efficacy was evaluated by Kaplan-Meier survival curves. The effect of [111In]In-DOTA-panitumumab (23 MBq; 15 µg) after tumor resection without local XRT was also studied. Tumor resection followed by XRT and RIT with 26 MBq [111In]In-DOTA-panitumumab significantly increased the median survival to 35 d compared to tumor resection with or without XRT (23-24 d; P < 0.0001). Local treatment with tumor resection and XRT followed by 2 × 10 MBq of [111In]In-DOTA-panitumumab, DOTA-panitumumab, or [111In]In-DOTA-IgG2 did not significantly improve median survival (26 days for all treatments). RIT alone with [111In]In-DOTA-panitumumab postresection of the tumor without XRT increased median survival to 29 days, though this was not significant. Despite significantly improved survival in mice treated with tumor resection, XRT, and RIT with [111In]In-DOTA-panitumumab, all mice eventually succumbed to advanced metastatic disease by 45 d post-tumor resection. SPECT/CT with [111In]In-DOTA-panitumumab, PET/MRI with [64Cu]Cu-DOTA-panitumumab F(ab')2, and PET/CT with [18F]FDG were used to detect recurrent and metastatic disease. Uptake of [111In]In-DOTA-panitumumab at 4 d p.i. in the MFP tumor was 26.8 ± 9.7% ID/g and in metastatic lymph nodes (LN), lungs, and liver was 34.2 ± 26.9% ID/g, 17.5 ± 6.0% ID/g, and 9.4 ± 2.4%ID/g, respectively, while uptake in the lungs (6.0 ± 0.9% ID/g) and liver (5.2 ± 2.9% ID/g) of non-tumor-bearing NRG was significantly lower (P < 0.05). Radiation-absorbed doses in metastatic LN, lungs, and liver were 9.7 ± 6.1, 6.4 ± 2.1, and 10.9 ± 2.7 Gy, respectively. In conclusion, we demonstrated that RIT with [111In]In-DOTA-panitumumab combined with tumor resection and XRT significantly improved the survival of mice with recurrent TNBC. However, the aggressive nature of 231/LM2-4 Luc+ tumors in NRG mice may have contributed to the tumor recurrence and progression observed.

Prevalence of Molecular Alterations in a Swiss Cohort of 512 Colorectal Carcinoma Patients by Targeted Next-Generation Sequencing Analysis in Routine Diagnostics.

INTRODUCTION: Colorectal carcinoma (CRC) is among the most common carcinomas in women and men. In the advanced stage, patients are treated based on the RAS status. Recent studies indicate that in the future, in addition to KRAS and NRAS, alterations in other genes, such as PIK3CA or TP53, will be considered for therapy. Therefore, it is important to know the mutational landscape of routinely diagnosed CRC. METHOD: We report the molecular profile of 512 Swiss CRC patients analyzed by targeted next-generation sequencing as part of routine diagnostics at our institute. RESULTS: Pathogenic and likely pathogenic variants were found in 462 (90%) CRC patients. Variants were detected in TP53 (54.3%), KRAS (48.2%), PIK3CA (15.6%), BRAF (13.5%), SMAD4 (10.5%), FBXW7 (7.8%), NRAS (3.5%), PTEN (2.7%), ERBB2 (1.6%), AKT1 (1.5%), and CTNNB1 (0.9%). The remaining pathogenic alterations were found in the genes ATM(n= 1), MAP2K1(n= 1), and IDH2(n= 1). DISCUSSION/CONCLUSIONS: Our analysis revealed the prevalence of potential predictive markers in a large cohort of CRC patients obtained during routine diagnostic analysis. Furthermore, our study is the first of this size to uncover the molecular landscape of CRC in Switzerland.

Selecting Optimal First-Line Treatment for Microsatellite Stable and Non-Mutated RAS/BRAF Metastatic Colorectal Cancer.

OPINION STATEMENT: Standard frontline treatment of metastatic colorectal cancer (CRC) is cytotoxic chemotherapy plus a biologic agent such as an anti-EGFR monoclonal antibody (cetuximab or panitumumab) or anti-VEGF antibody (bevacizumab). Predictive biomarkers include mismatch repair (MMR) status, and RAS and BRAF mutation status; and important factors in treatment selection include primary tumor location, intent of therapy, and potential toxicity, as well as patient age, comorbidities, and patient preference. To date, single-, double-, or triple-agent cytotoxic chemotherapy all have important roles in appropriately selected patients, with the addition of anti-VEGF or anti-EGFR antibody therapy based on the relevant predictive biomarker. Data indicate that patients with proficient MMR, RAS/BRAF wt mCRC are candidates for an anti-EGFR antibody plus doublet chemotherapy if they have a left-sided primary tumor, or for anti-VEGF (bevacizumab) plus doublet or triplet chemotherapy if they have a right-sided primary tumor. Future studies may provide more predictive biomarkers to further personalize therapy for this heterogeneous disease.

Risk factor analysis for anti-epidermal growth factor receptor monoclonal antibody-induced skin toxicities in real-world metastatic colorectal cancer treatment.

PURPOSE: Anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibodies are effective in treating RAS wild-type metastatic colorectal cancer (mCRC). However, their administration induces skin toxicity, markedly reducing patients' quality of life. This study is aimed at identifying the risk factors associated with anti-EGFR monoclonal antibody-induced skin toxicities. METHODS: Patients with mCRC (n = 116) who received anti-EGFR monoclonal antibody treatment were retrospectively evaluated. Primary endpoint was evaluation of the risk factors for grade ≥ 2 overall skin toxicities during all the treatment periods. Furthermore, factors associated with each grade ≥ 2 skin symptoms were assessed. RESULTS: Incidence of total grade ≥ 2 skin toxicity symptoms was 61.2%, and those of grade ≥ 2 rash, dry skin, fissures, and paronychia were 34.5%, 25.9%, 20.7%, and 25.0%, respectively. Multivariate logistic regression analyses revealed that liver metastasis was an independent risk factor for overall grade ≥ 2 skin toxicities (adjusted odds ratio [OR], 2.88; 95% confidence interval [CI], 1.22-6.78; P = 0.02) and prophylactic administration of antibiotics as a preventive factor (OR 0.10; 95%CI 0.01-0.91; P = 0.04). For grade ≥ 2 rash, prophylactic use of systemic antibiotics and topical steroid ointment was a preventive factor (OR 0.37; 95%CI 0.16-0.89; P = 0.03). Moreover, liver metastasis (OR 8.37; 95%CI 1.98-35.47; P = 0.004) and prophylactic administration of antibiotics (OR 0.15; 95%CI 0.03-0.76; P = 0.02) were significantly associated with grade ≥ 2 paronychia. CONCLUSION: Liver metastasis was suggested to be a risk factor for the incidence of overall grade ≥ 2 skin toxicities; moreover, preemptive systemic antibiotic administration drastically decreased this risk during all periods of anti-EGFR treatment for mCRC.

The efficacy and safety of anti-EGFR target agents in patients with potentially resectable metastatic colorectal cancer: a meta-analysis of randomized controlled trials.

BACKGROUND: Adding anti-epidermal growth factor receptor (anti-EGFR) target agents to conversion therapy may improve the resection rates and survival of patients with potentially resectable metastatic colorectal cancer (mCRC). This study aims to analyze the efficacy and safety of additional anti-EGFR target agents. METHODS: A systematic search was conducted on PubMed, Web of Science, Embase, and Cochrane Library. And all relevant studies published in English before January 2023 were collected to explore the impact of additional anti-EGFR targeted agent on the efficacy and safety of patients with potentially resectable mCRC (PROSPERO: CRD42022340523, https://www.crd.york.ac.uk/PROSPERO/ ). RESULTS: This study included a total of 8 articles, including 2618 patients. The overall response rate (ORR) and R0 resection rates of the experimental group were higher than those of the control group, while there was no significant difference in progression-free survival (PFS) and overall survival (OS) between the two groups. In RAS/KRAS wild-type patients, the ORR (RR: 1.20, 95% Cl: 1.02-1.41, p = 0.03), R0 resection rate (RR: 1.60, 95% Cl: 1.17-2.20, p = 0.003), PFS (HR: 0.80, 95% Cl: 0.68-0.93, p = 0.003), and OS (HR: 0.87, 95% Cl: 0.76-0.99, p = 0.031) of the experimental group were higher than those of the control group. While in KRAS mutant patients, there was no statistical difference between the two groups in ORR, R0 resection rate, PFS, and OS. CONCLUSION: The addition of anti-EGFR targeted agents can improve the prognosis of RAS/KRAS wild-type patients with potentially resectable mCRC, while KRAS mutant patients may not benefit. In addition, the overall safety factor was controllable.

A comparison of panitumumab and cetuximab in the treatment of KRAS wild-type metastatic colorectal cancer: a systematic review and meta-analysis.

AIM: Cetuximab and panitumumab are common antibodies against epidermal growth factor receptor (EGFR) that can be used in combination with chemotherapy for the treatment of metastatic colorectal cancer (mCRC). Although these two drugs are considered to be very similar, differences in the efficacy and safety of cetuximab and panitumumab are still unclear. We conducted this meta-analysis to explore the effects and adverse reactions of cetuximab and panitumumab in the treatment of mCRC. METHODS: We searched PubMed, the Cochrane Library, Embase, Web of Science, China national knowledge infrastructure (CNKI) and WanFang databases to identify records related to the efficacy and safety of cetuximab and panitumumab in the treatment of mCRC. The search terms were "cetuximab," "panitumumab," and "colorectal cancer." The deadline of searching was April 2022. Review manager 5.4 software was used to perform the statistical analysis for this meta-analysis. Pooled hazard ratio (HR) with 95% confidence intervals (CI) were calculated to evaluate the overall survival (OS) and progression free survival (PFS) of cetuximab and panitumumab in the treatment of mCRC. RESULTS: There was no significant difference in OS, PFS, and response rate (RR) between cetuximab arm and panitumumab arm (OS: HR = 0.91, 95% CI = 0.81-1.03, p = .14; PFS: HR = 0.92, 95% CI = 0.83-1.02, p = .11; RR: OR = 1.22, 95% CI = 0.96-1.61, p = .14). We also did not observe any statistical difference between both arms in incidence of acneiform rash, severe acneiform rash, diarrhea, and severe diarrhea (acneiform rash: OR = 1.09, 95% CI = 0.84-1.42, p = .51; severe acneiform rash: OR = 1.50, 95% CI = 0.80-2.81, p = .21; diarrhea: OR = 1.08, 95% CI = 0.82-1.42, p = .58; severe diarrhea: OR = 0.90, 95% CI = 0.44-1.84, p = .77). The incidence of paronychia was decreased in the panitumumab arm, but that of hypomagnesemia and severe hypomagnesemia were decreased in the cetuximab arm. (paronychia: OR = 0.74, 95% CI = 0.55-1.00, p = .05; hypomagnesemia: OR = 1.85, 95% CI =1.41-2.41, p < .00001; severe hypomagnesemia: OR = 2.66, 95% CI = 1.52-4.67, p = .0006). CONCLUSION: There was no significant difference in OS, PFS and RR between the cetuximab arm and panitumumab arm in the treatment of mCRC. For adverse reactions, the incidence of paronychia was decreased in the panitumumab arm, and the incidence of hypomagnesemia was deceased in the cetuximab arm.

Multicenter, single-arm, phase II study of the continuous use of panitumumab in combination with FOLFIRI after FOLFOX for RAS wild-type metastatic colorectal cancer: Exploratory sequential examination of acquired mutations in circulating cell-free DNA.

This multicenter single-arm, phase II study evaluated the efficacy and safety of uninterrupted panitumumab usage combined with cytotoxic doublets for unresectable/metastatic colorectal cancer (mCRC). Additionally, clinical value of the RAS/BRAF mutation status in circulating cell-free DNA (ccfDNA) was evaluated; this evaluation was measured independently of the protocol treatment. Eligible patients with RAS wild-type mCRC who had received the first-line panitumumab plus FOLFOX treatment were recruited and administered continuous panitumumab combined with FOLFIRI. Progression-free survival (PFS) at 6 months was the primary endpoint, with threshold and expected values of 35% and 50%, respectively. In total, 54 patients were enrolled between October 2017 and October 2019. The crude 6-month PFS rate was 37.0%, with a 4.8-month median PFS. The response rate and disease control rate were 16.7% and 50.0%, respectively. Notably, of the 54 participants, 17 showed RAS/BRAF mutations until the end of the protocol treatment and of the 22 patients with progressive disease as their best response, 10 possessed RAS/BRAF mutations in their plasma ccfDNA at baseline. The median PFS significantly differed among patients harboring tumors with BRAF and RAS mutations and those with wild-type tumors. In conclusion, our study failed to show the expected efficacy of the continuous panitumumab use in the second-line treatment. Liquid biopsy discriminated the duration of PFS according to the mutation status. The effectiveness of continuous treatment with panitumumab should be evaluated in patients with RAS/BRAF wild-type mCRC determined by liquid biopsy at the start of the second-line treatment.

N064A (Alliance): Phase II Study of Panitumumab, Chemotherapy, and External Beam Radiation in Patients with Locally Advanced Pancreatic Adenocarcinoma.

BACKGROUND: This North Central Cancer Treatment Group (NCCTG) N064A (Alliance) phase II trial evaluated upfront chemoradiotherapy incorporating the EGFR inhibitor panitumumab, followed by gemcitabine and panitumumab for unresectable, non-metastatic pancreatic cancer. METHODS: The treatment consisted of fluoropyrimidine and panitumumab given concurrently with radiotherapy followed by gemcitabine and panitumumab for 3 cycles followed by maintenance panitumumab. The primary endpoint was the 12-month overall survival (OS) rate and secondary endpoints included confirmed response rate (RR), OS, progression-free survival (PFS), and adverse events. Enrollment of 50 patients was planned and the study fully accrued. RESULTS: Fifty-two patients were enrolled, but only 51 were treated and included in the analysis. The median age of patients was 65 years and 54.9% were women. Twenty-two patients received at least 1 cycle of systemic therapy following radiotherapy, but 29 patients received chemoradiotherapy only without receiving subsequent chemotherapy after completion of chemoradiotherapy. The overall RR was 5.9% (95% CI: 1.2%-16.2%). The 12-month OS rate was 50% (95% CI: 38%-67%) which fell short of the per-protocol goal for success (51.1%). The median PFS was 7.4 months (95% CI: 4.5-8.6) and the median OS was 12.1 months (95% CI 7.9-15.9). Grade 3 or higher adverse events were reported by 88%. CONCLUSION: The combination of panitumumab, chemotherapy, and external beam radiation therapy was associated with very high rates of grades 3-4 toxicities and survival results did not meet the trial's goal for success. This regimen is not recommended for further study (ClinicalTrials.gov Identifier NCT00601627).

Selection of antibody and light exposure regimens alters therapeutic effects of EGFR-targeted near-infrared photoimmunotherapy.

Near-infrared photoimmunotherapy (NIR-PIT) is a cell-specific cancer therapy that uses an antibody-photoabsorber (IRDye700DX, IR700) conjugate (APC) and NIR light. Intravenously injected APC binds the target cells, and subsequent NIR light exposure induces immunogenic cell death only in targeted cells. Panitumumab and cetuximab are antibodies that target human epidermal growth factor receptor (hEGFR) and are suitable for NIR-PIT. In athymic nude mouse models, panitumumab-based NIR-PIT showed superior therapeutic efficacy compared to cetuximab-based NIR-PIT because of the longer half-life of panitumumab-IR700 (pan-IR700) compared with cetuximab-IR700 (cet-IR700). Two light exposures on two consecutive days have also been shown to induce superior effects compared to a single light exposure in the athymic nude mouse model. However, the optimal regimen has not been assessed in immunocompetent mice. In this study, we compared panitumumab and cetuximab in APCs for NIR-PIT, and single and double light exposures using a newly established hEGFR-expressing cancer cell line derived from immunocompetent C57BL/6 mice (mEERL-hEGFR cell line). Fluorescence imaging showed that the decline of pan-IR700 was slower than cet-IR700 confirming a longer clearance time. Among all the combinations tested, mice receiving pan-IR700 and double light exposure showed the greatest tumor growth inhibition. This group was also shown to activate CD8+ T lymphocytes in lymph nodes and accumulate CD8+ T lymphocytes to a greater extent within the tumor compared with the control group. These results showed that APCs with longer half-life and double light exposure lead to superior outcomes in cancer cell-targeted NIR-PIT in an immunocompetent mouse model.

Study protocol of the FIRE-8 (AIO-KRK/YMO-0519) trial: a prospective, randomized, open-label, multicenter phase II trial investigating the efficacy of trifluridine/tipiracil plus panitumumab versus trifluridine/tipiracil plus bevacizumab as first-line treatment in patients with metastatic colorectal cancer.

BACKGROUND: Initial systemic therapy for patients with metastatic colorectal cancer (mCRC) is usually based on two- or three-drug chemotherapy regimens with fluoropyrimidine (5-fluorouracil (5-FU) or capecitabine), oxaliplatin and/or irinotecan, combined with either anti-VEGF (bevacizumab) or, for RAS wild-type (WT) tumors, anti-EGFR antibodies (panitumumab or cetuximab). Recommendations for patients who are not eligible for intensive combination therapies are limited and include fluoropyrimidine plus bevacizumab or single agent anti-EGFR antibody treatment. The use of a monochemotherapy concept of trifluridine/ tipiracil in combination with monoclonal antibodies is not approved for first-line therapy, yet. Results from the phase II TASCO trial evaluating trifluridine/ tipiracil plus bevacicumab in first-line treatment of mCRC patients and from the phase I/II APOLLON trial investigating trifluridine/ tipiracil plus panitumumab in pre-treated mCRC patients suggest favourable activity and tolerability of these new therapeutic approaches. METHODS: FIRE-8 ( NCT05007132 ) is a prospective, randomized, open-label, multicenter phase II study which aims to evaluate the efficacy of first-line treatment with trifluridine/tipiracil (35 mg/m2 body surface area (BSA), orally twice daily on days 1-5 and 8-12, q28 days) plus either the anti-EGFR antibody panitumumab (6 mg/kg body weight, intravenously on day 1 and 15, q28 days) [arm A] or (as control arm) the anti-VEGF antibody bevacizumab (5 mg/kg body weight, intravenously on day 1 and 15, q28 days) [arm B] in RAS WT mCRC patients. The primary objective is to demonstrate an improved objective response rate (ORR) according to RECIST 1.1 from 30% (control arm) to 55% with panitumumab. With a power of 80% and a two-sided significance level of 0.05, 138 evaluable patients are needed. Given an estimated drop-out rate of 10%, 153 patients will be enrolled. DISCUSSION: To the best of our knowledge, this is the first phase II trial to evaluate the efficacy of trifluridine/tipiracil plus panitumumab in first-line treatment of RAS WT mCRC patients. The administration of anti-EGFR antibodies rather than anti-VEGF antibodies in combination with trifluridine/tipiracil may result in an increased initial efficacy. TRIAL REGISTRATION: EU Clinical Trials Register (EudraCT) 2019-004223-20 . Registered October 22, 2019, ClinicalTrials.gov NCT05007132 . Registered on August 12, 2021.

A multicenter study of skin toxicity management in patients with left-sided, RAS/BRAF wild-type metastatic colorectal cancer treated with first-line anti-EGFR-based doublet regimen: is there room for improvement?

BACKGROUND: Skin toxicity in patients affected by metastatic colorectal cancer (mCRC) treated with epidermal growth factor receptor (EGFR) inhibitors is well known. However, ad hoc ESMO guidelines have only recently been published. AIM AND METHODS: To describe the management (pre-emptive or reactive) of anti-EGFR-related cutaneous adverse events (AEs), in a real-life clinical context, in a selected population of patients with left-sided, metastatic RAS/BRAF wild-type mCRC treated with doublet chemotherapy plus anti-EGFR monoclonal antibody (i.e., panitumumab or cetuximab) as first-line regimen at 22 Institutions. The measured clinical outcomes were treatment-related adverse events, objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). RESULTS: Of 515 patients included in the analysis, 173 (33.6%) received a pre-emptive and 342 (66.4%) a reactive treatment. The median follow-up period for the overall population was 30.0 months. A significantly lower incidence of any grade acneiform rash was found in the pre-emptive compared to the reactive cohort both in the overall population (78.6% vs 94.4%, p < 0.001) and in patients treated with panitumumab (76.1% vs 93.7%, p < 0.001) or cetuximab (83.3% vs 95.4%, p = 0.004), respectively. A lower incidence of any grade (41.6% vs 50.9%, p = 0.047) but a higher incidence of G3-G4 (9.2% vs 4.7%, p = 0.042) paronychia/nail disorders were found in the pre-emptive compared to the reactive cohort. Nevertheless, a lower rate of patients within the reactive compared to the pre-emptive cohort was referred to dermatological counseling (21.4% vs 15.3%, respectively, p = 0.001). A higher rate of anti-EGFR therapy modification was needed in the pre-emptive compared to the reactive cohort (35.9% vs 41.6%, respectively, p < 0.001). The pre-emptive approach did not reduce the efficacy of antineoplastic therapy compared to the reactive in terms of ORR (69.2% vs 72.8%), median PFS (12.3 vs 13.0 months), and median OS (28.8 vs 33.5 months). CONCLUSION: Although recommended by international guidelines, the pre-emptive approach of anti-EGFR-related skin toxicity in mCRC patients still appears less adopted in daily clinical practice, compared to the reactive one. A wider reception and application of this indication is desirable to improve patients' quality of life without compromising the continuity and efficacy of antineoplastic therapy.

Prevention of Acne-Like Eruption Caused by Panitumumab Treatment through Oral Administration of Non-steroidal Anti-inflammatory Drugs.

Acne-like eruption caused by anti-epidermal growth factor receptor (EGFR) antibodies such as panitumumab reduces treatment adherence and patient QOL; an alternative therapy is desired. Meanwhile, the usefulness of oral Non-steroidal Anti-inflammatory Drugs (NSAIDs) for acne-like eruptions caused by low-molecular-weight EGFR inhibitors such as erlotinib has been reported in the treatment of lung cancer. This study aimed to investigate whether the combined use of oral NSAIDs and panitumumab for colorectal cancer patients helps prevent acne-like eruption. We retrospectively investigated 167 colorectal cancer patients who had been treated with panitumumab for three cycles or more. The observation period was set from the start of panitumumab treatment to the end of three cycles. Within this period, the incidence and severity of acne-like eruptions were compared. A total of 59 and 108 patients were in the NSAIDs use and non-use groups, respectively, showing differences in the incidence of acne-like eruption rates (78.0 vs. 90.7%, respectively; p = 0.033). In the use group, eruption severity grades 0, 1, 2, and 3 were observed in 13, 33, 13, and 0 patients, respectively; the corresponding values in the non-use group were 10, 60, 36, and 2, respectively (p = 0.007). Oral NSAIDs may help prevent acne-like eruptions caused by panitumumab.

Prospective case series of neuropathic cancer pain in patients treated with an EGFR-inhibitor.

BACKGROUND: Novel treatments of neuropathic pain are urgently needed. Rapid relief of neuropathic cancer pain in patients treated with epidermal growth factor receptor (EGFR) inhibitors have been reported. Experiments in rodent models confirm the pain relief and reveal novel mechanisms critically involving the EGFR. Clinical pain research is complicated and patients with advanced cancer are heterogeneous, often with complex, deteriorating clinical pictures, hampering feasibility of drug-trial procedures. ACTUAL CASE: Prospective case series exploring the EGFR inhibition/neuropathic cancer pain association in order to inform planning clinical trials. POSSIBLE COURSES OF ACTION: Symptom assessment method was tailored to what was ethical, feasible, and clinically relevant for each patient. FORMULATION OF A PLAN: Patients with neuropathic cancer pain treated off-label with the monoclonal antibody panitumumab were studied to assess feasibility of different measurement tools. OUTCOME: Fourteen of 20 patients (70%) experienced clinically significant pain relief. There was good concordance in patient and physician-reported outcomes. LESSONS: Results support panitumumab's potential to be of significant benefit to patients with refractory neuropathic cancer pain. Findings also reinforce the difficulty of using conventional drug trial endpoints and designs in this population. VIEW: Innovative research methods must be considered for much needed pivotal trials.

Primary tumor location as a predictor of survival in patients with RAS wild-type colorectal cancer who receive molecularly targeted drugs as first-line therapy: a multicenter real-world observational study by the Japanese Society for Cancer of the Colon and Rectum.

BACKGROUND: Primary tumor location is considered a predictor of overall survival (OS) in RAS wild-type (WT) metastatic colorectal cancer (mCRC) treated with bevacizumab (BEV) or an anti-epidermal growth factor antibody (cetuximab or panitumumab [CET/PAN]) as first-line molecularly targeted therapy. BEV is recommended for right-sided mCRC and CET/PAN for left-sided mCRC based on post-hoc analyses of clinical trial data, but real-world evidence is lacking. METHODS: We retrospectively collected data of patients who started BEV or CET/PAN plus 5-fluorouracil-based doublet chemotherapy between January 2013 and December 2016 as first-line treatment for RAS WT mCRC at any of 24 Japanese institutions. OS was compared between the BEV and CET/PAN groups according to primary tumor location by Cox multivariate regression analysis in the full cohort and in a propensity score-matched cohort. RESULTS: In total, 935 patients were enrolled. Median OS was 24.6 months with BEV and 20.9 months with CET/PAN in right-sided mCRC (n = 213; adjusted hazard ratio [HR] 0.73, 95% confidence interval [CI] 0.50-1.06) and 35.7 months and 30.0 months, respectively, in left-sided mCRC (n = 722; adjusted HR 0.92, 95% CI 0.74-1.13). In the propensity score-matched cohort, OS was significantly better in the BEV group than in the CET/PAN group in right-sided mCRC (HR 0.52, 95% CI 0.28-0.96) but was not significantly different in left-sided mCRC (HR 0.78, 95% CI 0.53-1.07). CONCLUSION: Real-world data showed that OS was better with BEV than with CET/PAN in right-sided mCRC. However, there was no significant difference in OS in left-sided mCRC.