Anti-EGFR Rechallenge in Patients With Refractory ctDNA RAS/BRAF wt Metastatic Colorectal Cancer: A Nonrandomized Controlled Trial

Importance

The available evidence regarding anti-epidermal growth factor receptor (EGFR) inhibitor rechallenge in patients with refractory circulating tumor DNA (ctDNA) RAS/BRAF wild-type (wt) metastatic colorectal cancer (mCRC) is derived from small retrospective and prospective studies.

Objective

To evaluate the efficacy of anti-EGFR rechallenge in patients with refractory ctDNA RAS/BRAF wt mCRC.

Design, Setting, and Participants

This nonrandomized controlled trial used a pooled analysis of individual patient data from patients with RAS/BRAF wt ctDNA mCRC enrolled in 4 Italian trials (CAVE, VELO, CRICKET, and CHRONOS) and treated with anti-EGFR rechallenge between 2015 and 2022 (median [IQR] follow-up, 28.1 [25.8-35.0] months).

Intervention

Patients received anti-EGFR rechallenge therapy, including cetuximab plus avelumab, trifluridine-tipiracil plus panitumumab, irinotecan plus cetuximab, or panitumumab monotherapy.

Main Outcomes and Measures

Overall survival (OS), progression-free survival (PFS), overall response rate (ORR), and disease control rate (DCR) were calculated. Exploratory subgroup analysis evaluating several clinical variables was performed. Safety was reported.

Results

Overall, 114 patients with RAS/BRAF wt ctDNA mCRC (median [IQR] age, 61 [29-88] years; 66 men [57.9%]) who received anti-EGFR rechallenge as experimental therapy (48 received cetuximab plus avelumab, 26 received trifluridine-tipiracil plus panitumumab, 13 received irinotecan plus cetuximab, and 27 received panitumumab monotherapy) were included in the current analysis. Eighty-three patients (72.8%) had received 2 previous lines of therapy, and 31 patients (27.2%) had received 3 or more previous lines of therapy. The ORR was 17.5% (20 patients), and the DCR was 72.3% (82 patients). The median PFS was 4.0 months (95% CI, 3.2-4.7 months), and the median OS was 13.1 months (95% CI, 9.5-16.7 months). The subgroup of patients without liver involvement had better clinical outcomes. The median PFS was 5.7 months (95% CI, 4.8-6.7 months) in patients without liver metastasis compared with 3.6 months (95% CI, 3.3-3.9 months) in patients with liver metastasis (hazard ratio, 0.56; 95% CI, 0.37-0.83; P = .004). The median OS was 17.7 months (95% CI, 13-22.4 months) in patients without liver metastasis compared with 11.5 months (95% CI, 9.3-13.9 months) in patients with liver metastasis (hazard ratio, 0.63; 95% CI, 0.41-0.97; P = .04). Treatments showed manageable toxic effects.

Conclusions and Relevance

These findings suggest that anti-EGFR rechallenge therapy has promising antitumor activity in patients with refractory ctDNA RAS/BRAF wt mCRC. Within the limitation of a subgroup analysis, the absence of liver metastases was associated with significant improved survival.

Trial Registration

ClinicalTrials.gov Identifiers: NCT02296203; NCT04561336; NCT03227926; NCT05468892.

Negative Hyperselection of Resistance Mutations for Panitumumab Maintenance in RAS Wild-Type Metastatic Colorectal Cancer (PanaMa Phase II Trial, AIO KRK 0212)

PURPOSE

We evaluated additional mutations in RAS wild-type (WT) metastatic colorectal cancer (mCRC) as prognostic and predictive biomarkers for the efficacy of added panitumumab to a 5-fluorouracil plus folinic acid (FU/FA) maintenance as pre-specified analysis of the randomized PanaMa trial.

PATIENTS AND METHODS

Mutations (MUT) were identified using targeted next-generation sequencing (NGS; Illumina Cancer Hotspot Panel v2) and IHC. RAS/BRAF V600E/PIK3CA/AKT1/ALK1/ERBB2/PTEN MUT and HER2/neu overexpressions were negatively hyperselected and correlated with median progression-free survival (PFS) and overall survival (OS) since start of maintenance treatment, and objective response rates (ORR). Univariate/multivariate Cox regression estimated hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

202 of 248 patients (81.5%) of the full analysis set (FAS) had available NGS data: hyperselection WT, 162 (80.2%); MUT, 40 (19.8%). From start of maintenance therapy, hyperselection WT tumors were associated with longer median PFS as compared with hyperselection MUT mCRC (7.5 vs. 5.4 months; HR, 0.75; 95% CI, 0.52-1.07; P = 0.11), OS (28.7 vs. 22.2 months; HR, 0.53; 95% CI, 0.36-0.77; P = 0.001), and higher ORR (35.8% vs. 25.0%, P = 0.26). The addition of panitumumab to maintenance was associated with significant benefit in hyperselection WT tumors for PFS (9.2 vs. 6.0 months; HR, 0.66; 95% CI, 0.47-0.93; P = 0.02) and numerically also for OS (36.9 vs. 24.9 months; HR, 0.91; 95% CI, 0.61-1.36; P = 0.50), but not in hyperselection MUT tumors. Hyperselection status interacted with maintenance treatment arms in terms of PFS (P = 0.06) and OS (P = 0.009).

CONCLUSIONS

Extended molecular profiling beyond RAS may have the potential to improve the patient selection for anti-EGFR containing maintenance regimens.

Panitumumab-IRDye800 Improves Laryngeal Tumor Mapping During Transoral Laser Microsurgery

Transoral laser microsurgery represents the primary surgical modality for early laryngeal cancers with oncologic outcomes equivalent to radiotherapy. Accurate tumor mapping and margin assessment can be difficult, however, particularly during piecemeal or ablative resections, and for tumors with a wider geographic footprint. Tumor-targeted fluorescence-guided surgery in patients with head and neck cancer has empirically improved tumor and margin identification; this case details, for the first time, a fluorescence-guided surgical resection of a T2N0M0 transglottic tumor using panitumumab-IRDye800, an epidermal growth factor receptor monoclonal antibody covalently linked to near-infrared (NIR) dye. Laryngoscope, 134:1837-1841, 2024.

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.

Exploring the Sensitivity of Antibody-Drug Conjugate Efficacy to the Selection of Payload, Antibody, and Cell line

Antibody-drug conjugates (ADCs) make up a growing class of targeted therapeutics with important applications in cancer treatment. ADCs are highly modular in nature and thus can be engineered to target any cancer type, but their efficacy is strongly influenced by the specific choice of payload, antibody, and target cell. Considering the number of possible antibody-payload combinations, ADC development would benefit from an efficient method to narrow the number of ADC compositions to those with the highest and most universal potency prior to assessing pharmacokinetics and pharmacodynamics in animal models. To facilitate the identification of optimal ADC compositions, we describe the use of photoreactive antibody-binding domain-drug conjugates (known commercially as oYo-Link) to enable the site-specific labeling of off-the-shelf antibodies. This approach allows for the rapid generation of ADCs with a drug-to-antibody ratio of ∼2 with no subsequent purification required. As a demonstration of this approach, ADCs were generated with different combinations of tubulin-inhibitor drugs (DM1, DM4, VcMMAE, and VcMMAF) and anti-EGFR antibodies (cetuximab, panitumumab, anti-EGFR clone 425, and anti-EGFR clone 528) and were delivered to three EGFR-expressing cell lines (A431, A549, and MDA-MB-231). Real-time cytolysis assays indicated that the most effective antibody varied based on the choice of cell line: cetuximab was most potent against A431 cells, while 425 and 528 led to the greatest cytotoxicity against A549 and MDA-MB-231 cells. These results did not correlate with differences in measured anti-EGFR binding affinity as cetuximab had the highest affinity across all three cell lines, while 425 and 528 had the lowest affinities for all three cell lines. Panitumumab, which had the second-highest anti-EGFR affinity, exhibited the least effective cytolysis across A431, A549, and MDA-MB-231 cells. By demonstrating that ADC potency toward a given target is dependent on both the antibody and drug chosen, these findings can guide the selection of ADCs for further in vivo analysis.

Combating KRASG12C Inhibitor Resistance

To boost KRASG12C inhibitor efficacy and counter cancer cells' ability to mount resistance, combination strategies are being utilized. Findings from the phase III CodeBreaK 300 trial indicate that adding the EGFR inhibitor panitumumab to sotorasib bests standard care for chemorefractory KRASG12C colorectal cancer. Joint SHP2 blockade is another approach that shows signs of activity in reversing acquired KRASG12C inhibitor resistance, according to preliminary phase I data.

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.

Initial Panitumumab Plus Fluorouracil, Leucovorin, and Oxaliplatin or Plus Fluorouracil and Leucovorin in Elderly Patients With RAS and BRAF Wild-Type Metastatic Colorectal Cancer: The PANDA Trial by the GONO Foundation

PURPOSE

To verify whether both doublet chemotherapy with a modified schedule of fluorouracil, leucovorin, and oxaliplatin (mFOLFOX) and monochemotherapy with fluorouracil plus leucovorin (5-FU + LV) achieve satisfactory efficacy when both regimens are combined with panitumumab (PAN) as initial treatment of elderly patients with RAS/BRAF wild-type metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

PANDA (ClinicalTrials.gov identifier: NCT02904031) was an open-label, randomized phase II noncomparative trial in previously untreated patients age 70 years and older with unresectable RAS/BRAF wild-type mCRC. Patients were randomly assigned 1:1 to mFOLFOX + PAN (arm A) or 5-FU + LV + PAN (arm B) for up to 12 cycles, followed by PAN maintenance. The primary end point was progression-free survival (PFS). In each arm, assuming a null hypothesis of median PFS time ≤6 months and target PFS ≥9.65, 90 patients per arm were needed to achieve 90% power and 5% type I error (one-sided Brookmeyer-Crowley test).

RESULTS

Between July 2016 and April 2019, 91 patients were randomly assigned to arm A and 92 to arm B. At a median follow-up of 50.0 months (IQR, 45.6-56.4), median PFS was 9.6 and 9.0 months for arm A and B, respectively (P < .001 in each arm). Overall response rate was 69% and 52%, whereas median overall survival was 23.5 and 22.0 months in arm A and B, respectively. The overall rate of grade >2 chemotherapy-related adverse events was 60% and 37%, respectively. Baseline G8 and Chemotherapy Risk Assessment Scale for High-Age Patients scores were prognostic, but they were not associated with efficacy and safety of the two arms.

CONCLUSION

Both mFOLFOX and 5-FU + LV + PAN are reasonable options as initial therapy of elderly patients with RAS/BRAF wild-type mCRC. 5-FU + LV + PAN is associated with a better safety profile.

[Treatment Strategy for Familial Adenomatous Polyposis Presenting with Obstructive Colorectal Cancer and Concurrent Liver Metastasis]

A 27-year-old man was referred to our hospital for a detailed examination of abdominal distention, bloody stool, anorectal pain, and weight loss. A colonoscopy revealed a circumferential type 2 tumor at 9 cm from the anal verge which was diagnosed as an adenocarcinoma based on biopsy. Contrast-enhanced CT of the abdomen showed an elevated perineal lipid concentration in the rectum(Ra)which was suspicious for clinical T4a stage, and simultaneous S7/8 liver metastasis. We strongly suspected familial adenomatous polyposis(FAP)because his mother had a past history of total proctocolectomy for FAP. We decided to first create a loop stoma at the transverse colon for the obstructive rectal cancer, and then administer neoadjuvant chemotherapy(mFOLFOX6 plus panitumumab). We performed total proctocolectomy with permanent stoma and S8 ventral resection for the liver metastasis after 5 courses of mFOLFOX6 plus panitumumab. As for clinicopathological findings, round 50 polyps were identified in the colon and rectum, and rectal cancer invaded into the muscularis propria. Finally, the patient was diagnosed as a clinically attenuated FAP with ypT2 rectal cancer.

[A Case of Descending Colon Cancer with Distant Metastasis That Was Controlled Severe Side Effects of Chemotherapy and Achieved Long-Term CR]

A 69-year-old male patient with descending colon cancer with para-aortic lymph node metastasis underwent surgery to resect the primary tumor. After the surgery mFOLFOX6 plus panitumumab was introduced. Because 2 times drug-induced lung disease and Stevens Johnson syndrome were occurred, changes in chemotherapy regimen were required. 18 months after administration, complete response was achieved. The chemotherapy was discontinued 48 months after administration. He is alive without recurrence for 32 months after completion of treatment.

Associations between AI-Assisted Tumor Amphiregulin and Epiregulin IHC and Outcomes from Anti-EGFR Therapy in the Routine Management of Metastatic Colorectal Cancer

PURPOSE

High tumor production of the EGFR ligands, amphiregulin (AREG) and epiregulin (EREG), predicted benefit from anti-EGFR therapy for metastatic colorectal cancer (mCRC) in a retrospective analysis of clinical trial data. Here, AREG/EREG IHC was analyzed in a cohort of patients who received anti-EGFR therapy as part of routine care, including key clinical contexts not investigated in the previous analysis.

EXPERIMENTAL DESIGN

Patients who received panitumumab or cetuximab ± chemotherapy for treatment of RAS wild-type mCRC at eight UK cancer centers were eligible. Archival formalin-fixed paraffin-embedded tumor tissue was analyzed for AREG and EREG IHC in six regional laboratories using previously developed artificial intelligence technologies. Primary endpoints were progression-free survival (PFS) and overall survival (OS).

RESULTS

A total of 494 of 541 patients (91.3%) had adequate tissue for analysis. A total of 45 were excluded after central extended RAS testing, leaving 449 patients in the primary analysis population. After adjustment for additional prognostic factors, high AREG/EREG expression (n = 360; 80.2%) was associated with significantly prolonged PFS [median: 8.5 vs. 4.4 months; HR, 0.73; 95% confidence interval (CI), 0.56-0.95; P = 0.02] and OS [median: 16.4 vs. 8.9 months; HR, 0.66 95% CI, 0.50-0.86; P = 0.002]. The significant OS benefit was maintained among patients with right primary tumor location (PTL), those receiving cetuximab or panitumumab, those with an oxaliplatin- or irinotecan-based chemotherapy backbone, and those with tumor tissue obtained by biopsy or surgical resection.

CONCLUSIONS

High tumor AREG/EREG expression was associated with superior survival outcomes from anti-EGFR therapy in mCRC, including in right PTL disease. AREG/EREG IHC assessment could aid therapeutic decisions in routine practice. See related commentary by Randon and Pietrantonio, p. 4021.

Exploring proteoforms of the IgG2 monoclonal antibody panitumumab using microchip capillary electrophoresis-mass spectrometry

The IgG2 type monoclonal antibody panitumumab is an anti-epidermal growth factor receptor (EGFR) drug used for the treatment of EGFR-expressing, chemotherapy resistant, metastatic colorectal carcinoma. In this study, panitumumab drug product was first analysed using size exclusion chromatography coupled to mass spectrometry for rapid identity testing. The experimental data led to the identification of two panitumumab isoforms with several prominent forms remaining unidentified, despite apparently low sample complexity. Microchip capillary electrophoresis-mass spectrometry (CE-MS) was subsequently utilised for a more detailed characterization. It was observed that panitumumab is subject to partial N-terminal pyroglutamate formation. Incomplete conversion is uncharacteristic for N-terminally exposed glutamines and in case of panitumumab gives rise to forms which show successive mass offsets of 17 Da, respectively. If not separated before mass spectrometric analysis, e.g. by capillary electrophoresis, such near isobaric species coalesce into single MS peaks, which subsequently hampers or prevents their assignment. With a total of 42 panitumumab isoforms assigned by CE-MS, these observations highlight a potential pitfall of commonly applied rapid identity testing workflows and demonstrate that even low complexity biopharmaceuticals can require separation strategies which offer high separation selectivity for species close in mass.

The prognostic role of HIF-1α and NF-κB expression in RAS wild-type metastatic colorectal cancer: A Turkish Oncology Group (TOG) study

BACKGROUND

Not all RAS wild-type metastatic colorectal cancer (mCRC) patients experience the same benefit from anti-epidermal growth factor receptor (EGFR) treatments. Studies have shown that nuclear factor-κB (NF-κB), hypoxia-inducible factor-1α (HIF-1α), interleukin 8 (IL-8) and transforming growth factor β (TGF-β) may be therapeutic targets for mCRC. The aim of this study was to clarify the prognostic value of NF-κB, HIF-1α, IL-8, and TGF-β expression in patients with left-sided mCRC receiving EGFR inhibitors.

METHODS

Patients with RAS wild-type, left-sided mCRC treated with anti-EGFR on the first line between September 2013 and April 2022 were included. Immunohistochemical staining for NF-κB, HIF-1α, IL-8 and TGF-β was performed from tumor tissues of 88 patients. Patients were divided into NF-κB, HIF-1α, IL-8 and TGF-β expression positive and negative group, moreover, expression positive group were also divided into two group as expression intensity low and high group. The median follow-up was 25.2 months.

RESULTS

Median progression-free survival (PFS) was 8.1 (6-10.2) months in the cetuximab group, 11.3 (8.5-14) months in the panitumumab group (p = 0.09). Median overall survival (OS) was 23.9 (4.3-43.4) months in the cetuximab group, 26.9 (15.9-31.9) months in the panitumumab group (p = 0.8). Cytoplasmic NF-κB expression was present in all patients. The mOS was 19.8 (11-28.6) months in NF-κB expression intensity low group and 36.5 (20.1-52.8) months in high group (p = 0.03). The mOS of the HIF-1α expression negative group was significantly longer compared with expression positive group (p = 0.014). There was no significant difference in IL-8 and TGF-β expression status on mOS and mPFS (for all, p > 0.05). Positive expression of HIF-1α was poor prognostic for mOS in the univariate analysis (HR:2.7, 95% CI 1.18-6.52, p = 0.02) and in multivariate analysis (HR 3.69, 95% CI 1.41-9.6, p = 0.008). High cytoplasmic expression intensity of NF-κB was found to have a good prognostic value for mOS (HR 0.47, 95% CI 0.26-0.85, p = 0.01).

CONCLUSION

High cytoplasmic expression intensity of NF-κB and negative expression of HIF-1α could be a good prognostic marker for mOS in RAS wild-type left-sided mCRC.

γ-radiation for decreasing the clonogenic survival in vitro of human pancreatic ductal adenocarcinoma (PDAC) cells

INTRODUCTION

Our objective was to compare [64Cu]Cu-NOTA-panitumumab F(ab')2 and [177Lu]Lu-NOTA-panitumumab F(ab')2 radioimmunotherapy (RIT) agents for decreasing the clonogenic survival fraction (SF) in vitro of EGFR-positive human pancreatic ductal adenocarcinoma (PDAC) cell lines and estimate the relative biological effectiveness (RBE) vs. γ-radiation (XRT).

METHODS

EGFR-positive PDAC cell lines (AsPC-1, PANC-1, MIAPaCa-2, Capan-1) and EGFR-knockout PANC-1 EGFR KO cells were treated in vitro for 18 h with (0-19.65 MBq; 72 nmols/L) of [64Cu]Cu-NOTA-panitumumab F(ab')2 or [177Lu]Lu-NOTA-panitumumab F(ab')2 or XRT (0-8 Gy) followed by clonogenic assay. The SF was determined after culturing single treated cells for 14 d. Cell fractionation studies were performed for cells incubated with 1 MBq (72 nmols/L) of [64Cu]Cu-NOTA-panitumumab F(ab')2 or [177Lu]Lu-NOTA-panitumumab F(ab')2 for 1, 4, or 24 h to estimate the time-integrated activity (Ã) on the cell surface, cytoplasm, nucleus and medium. Radiation absorbed doses in the nucleus were calculated by multiplying à by S-factors calculated by Monte Carlo N Particle (MCNP) modeling using monolayer cell culture geometry. The SF of PDAC cells was plotted vs. dose and fitted to a linear quadratic model to estimate the dose required to decrease the SF to 0.1 (D10). The D10 for RIT agents were compared to XRT to estimate the RBE. DNA double-strand breaks (DSBs) caused by [64Cu]Cu-NOTA-panitumumab F(ab')2 or [177Lu]Lu-NOTA-panitumumab F(ab')2 continuous exposure for 5 h or 20 h were probed by immunofluorescence for γ-H2AX. Relative EGFR expression of PDAC cells was assessed by flow cytometry (scored + to +++) and cell doubling times for untreated cells were determined.

RESULTS

The D10 for [64Cu]Cu-NOTA-panitumumab F(ab')2 ranged from 9.1 Gy (PANC-1) to 39.9 Gy (Capan-1). The D10 for [177Lu]Lu-NOTA-panitumumab F(ab')2 ranged from 11.7 Gy (AsPC-1) to 170.8 Gy (Capan-1). The D10 for XRT ranged from 2.5 Gy (Capan-1) to 6.7 Gy (PANC-1 EGFR KO). D10 values were not correlated with EGFR expression over a relatively narrow range (++ to +++) or with cell doubling times. Based on D10 values, PANC-1 EGFR KO cells were 1.6-fold less sensitive than PANC-1 cells to [64Cu]Cu-NOTA-panitumumab F(ab')2 and 1.9-fold less sensitive to [177Lu]Lu-NOTA-panitumumab F(ab')2. The RBE for [64Cu]Cu-NOTA-panitumumab F(ab')2 ranged from 0.06 for Capan-1 cells to 0.45 for PANC-1 cells. The RBE for [177Lu]Lu-NOTA-panitumumab F(ab')2 ranged from 0.015 for Capan-1 cells to 0.28 for AsPC-1 cells. DNA DSBs were detected in PDAC cells exposed to [64Cu]Cu-NOTA-panitumumab F(ab')2 or [177Lu]Lu-NOTA-panitumumab F(ab')2 but were not correlated with the SF of the cells.

CONCLUSIONS

We conclude that at the same dose delivered to the cell nucleus [64Cu]Cu-NOTA-panitumumab F(ab')2 and [177Lu]Lu-NOTA-panitumumab F(ab')2 were less radiobiologically effective than XRT for decreasing the SF of human PDAC cells, but [64Cu]Cu-NOTA-panitumumab F(ab')2 was more cytotoxic than [177Lu]Lu-NOTA-panitumumab F(ab')2 except for AsPC-1 cells which were more sensitive to [177Lu]Lu-NOTA-panitumumab F(ab')2.

ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE

This study demonstrates that higher radiation doses may be required for RIT than XRT to achieve radiobiologically equivalent effects when used to treat PDAC.

Near-infrared photoimmunotherapy (NIR-PIT) of bone metastases

The bones are a common site for metastasis arising from solid tumors such as breast and prostate cancer. Chemotherapy, including immunotherapy, is rarely curative. Radiotherapy with pain palliation can temporize bone metastases but is generally considered a short-term solution and retreatment is difficult. Surgery is often necessary, yet recovery times might exceed life expectancy. Therefore, there is a need to develop new approaches to bone metastases that are effective but minimally invasive. Near-infrared photoimmunotherapy (NIR-PIT) uses antibodies labeled with IRDye700DX (IR700) which is activated by NIR light, resulting in rapid cell membrane damage and immunogenic cell death. NIR-PIT using an anti-epidermal growth factor receptor (EGFR) antibody-IR700 conjugate in patients with recurrent head and neck cancer received qualified approval in Japan in 2020 and is now widely used there. However, no bone metastases have yet been treated. In this study, the efficacy of NIR-PIT for bone metastases was investigated using a bone metastases mouse model successfully established by caudal artery injection of a human triple-negative breast cancer cell line, MDAMB468-GFP/luc. The bone metastatic lesions were treated with NIR-PIT using the anti-EGFR antibody, panitumumab-IR700 conjugate. Bioluminescence imaging and histological evaluation showed that EGFR-targeted NIR-PIT has a therapeutic effect on bone metastatic lesions in mice. In addition, micro-CT showed that repeated NIR-PIT led to repair of metastasis-induced bone destruction and restored bone cortex continuity consistent with healing. These data suggest that NIR-PIT has the potential for clinical application in the treatment of bone metastases.

Preoperative Chemotherapy for Operable Colon Cancer: Mature Results of an International Randomized Controlled Trial

PURPOSE

Neoadjuvant chemotherapy (NAC) has potential advantages over standard postoperative chemotherapy for locally advanced colon cancer but requires formal evaluation.

METHODS

Patients with radiologically staged T3-4, N0-2, M0 colon cancer were randomly allocated (2:1) to 6 weeks oxaliplatin-fluoropyrimidine preoperatively plus 18 postoperatively (NAC group) or 24 weeks postoperatively (control group). Patients with RAS-wildtype tumors could also be randomly assigned 1:1 to receive panitumumab or not during NAC. The primary end point was residual disease or recurrence within 2 years. Secondary outcomes included surgical morbidity, histopathologic stage, regression grade, completeness of resection, and cause-specific mortality. Log-rank analyses were by intention-to-treat.

RESULTS

Of 699 patients allocated to NAC, 674 (96%) started and 606 (87%) completed NAC. In total, 686 of 699 (98.1%) NAC patients and 351 of 354 (99.2%) control patients underwent surgery. Thirty patients (4.3%) allocated to NAC developed obstructive symptoms requiring expedited surgery, but there were fewer serious postoperative complications with NAC than with control. NAC produced marked T and N downstaging and histologic tumor regression (all P < .001). Resection was more often histopathologically complete: 94% (648/686) versus 89% (311/351), P < .001. Fewer NAC than control patients had residual or recurrent disease within 2 years (16.9% [118/699] v 21.5% [76/354]; rate ratio, 0.72 [95% CI, 0.54 to 0.98]; P = .037). Tumor regression correlated strongly with freedom from recurrence. Panitumumab did not enhance the benefit from NAC. Little benefit from NAC was seen in mismatch repair-deficient tumors.

CONCLUSION

Six weeks of preoperative oxaliplatin-fluoropyrimidine chemotherapy for operable colon cancer can be delivered safely, without increasing perioperative morbidity. This chemotherapy regimen, when given preoperatively, produces marked histopathologic down-staging, fewer incomplete resections, and better 2-year disease control. Histologic regression after NAC is a strong predictor of lower postoperative recurrence risk so has potential use as a guide for postoperative therapy. Six weeks of NAC should be considered as a treatment option for locally advanced colon cancer.

Comprehensive Analyses of the Intracellular and in Vivo Disposition of Fab- Small Interfering RNA Conjugate to Identify Key Issues to Improve Its in Vivo Activity

Comprehensive analyses of intracellular disposition and in vivo pharmacokinetics were performed for small interfering RNA (siRNA) conjugated with the Fab fragment of panitumumab, a fully humanized monoclonal antibody against epidermal growth factor receptor (EGFR). The Fab-siRNA conjugate was internalized into EGFR-expressing cancer cells in an antigen-dependent manner. Intracellular disposition was quantitatively evaluated using fluorescent-labeled panitumumab and confocal microscopy. The majority of internalized panitumumab was suggested to be transferred into lysosomes. In vivo pharmacokinetics were evaluated in EGFR-expressing tumor-bearing mice. Intact Fab-siRNA was measured by immunoprecipitation using anti-Fab antibody followed by quantitative polymerase chain reaction. The Fab portion was measured by a ligand binding assay. Intact Fab-siRNA concentrations rapidly decreased in the plasma and tumor, although the Fab portion concentration remained high, suggesting extensive degradation in the linker-siRNA portion. After incubation of Fab-siRNA in mouse plasma, samples were digested with proteinase K, and extracted siRNA tagged with Fab-derived peptide was subjected to an ion-pair reversed-phase liquid chromatography with mass spectrometry analysis. Results suggested that hydrolysis from the 3' end of the antisense strand of siRNA is the major metabolizing pathway. Based on these findings, endosomal escape and stability in lysosomes, blood, and tumor are key factors to improve to achieve efficient target gene knockdown in tumors, and stabilizing the 3' end of the antisense strand was suggested to be most efficient. Our approaches clearly identified the key issues of Fab-siRNA from a pharmacokinetics aspect, which will be useful for improving the in vivo activity of siRNA conjugated with not only Fab but also other immunoproteins. SIGNIFICANCE STATEMENT: The intracellular and in vivo disposition of Fab-small interfering RNA (siRNA) conjugate was comprehensively investigated using various approaches, including newly developed analytical methods. This study clearly shows that improvements in siRNA stability in lysosomes, blood, and tumor are needed for target gene knockdown in tumors. The major metabolic pathway of Fab-siRNA is 3' exonuclease degradation, suggesting that optimization of the conjugation site to Fab might help improve stability.

Opposing Effects of EGF Receptor Signaling on Proliferation and Differentiation Initiated by EGF or TSH/EGF Receptor Transactivation

Regulation of thyroid cells by thyrotropin (TSH) and epidermal growth factor (EGF) has been known but different effects of these regulators on proliferation and differentiation have been reported. We studied these responses in primary cultures of human thyroid cells to determine whether TSH receptor (TSHR) signaling may involve EGF receptor (EGFR) transactivation. We confirm that EGF stimulates proliferation and de-differentiation whereas TSH causes differentiation in the absence of other growth factors. We show that TSH/TSHR transactivates EGFR and characterize it as follows: (1) TSH-induced upregulation of thyroid-specific genes is inhibited by 2 inhibitors of EGFR kinase activity, AG1478 and erlotinib; (2) the mechanism of transactivation is independent of an extracellular EGFR ligand by showing that 2 antibodies, cetuximab and panitumumab, that completely inhibited binding of EGFR ligands to EGFR had no effect on transactivation, and by demonstrating that no EGF was detected in media conditioned by thyrocytes incubated with TSH; (3) TSH/TSHR transactivation of EGFR is different than EGFR activation by EGF by showing that EGF led to rapid phosphorylation of EGFR whereas transactivation occurred in the absence of receptor phosphorylation; (4) EGF caused downregulation of EGFR whereas transactivation had no effect on EGFR level; (5) EGF and TSH stimulation converged on the protein kinase B (AKT) pathway, because TSH, like EGF, stimulated phosphorylation of AKT that was inhibited by EGFR inhibitors; and (6) TSH-induced upregulation of thyroid genes was inhibited by the AKT inhibitor MK2206. Thus, TSH/TSHR causes EGFR transactivation that is independent of extracellular EGFR ligand and in part mediates TSH regulation of thyroid hormone biosynthetic genes.

[A Case of Pembrolizumab Therapy Markedly Effective for Advanced Recurrent Colorectal Cancer]

We report a case of pembrolizumab therapy as the fourth-line therapy for colorectal cancer and multiple lymph node recurrence with high-frequency microsatellite instability(MSI-High). The patient was a 75-year-old woman diagnosed with ascending colon cancer(pT4aN2bM0, Stage Ⅲc)and underwent laparoscopic right hemicolectomy, D3 dissection, and functional end-to-end anastomosis after inserting a self-expandable metallic stent. Postoperative adjuvant chemotherapy was performed, and the patient was followed. Postoperative 1 year 8 months, lymph node recurrence was indicated, and FOLFOX plus panitumumab therapy was introduced. FOLFIRI plus ramucirumab therapy and FTD/TPI were introduced as the second-line and third-line treatments, respectively; however, recurrent lymph nodes were further exacerbated and showed treatment resistance. Lymph node biopsy confirmed MSI-High, and pembrolizumab therapy was initiated as the fourth-line treatment. After the therapy, the lymph nodes reduced markedly. The patient remains undergoing chemotherapy without any adverse events.

First Clinical Results of Fluorescence Lifetime-enhanced Tumor Imaging Using Receptor-targeted Fluorescent Probes

PURPOSE

Fluorescence molecular imaging, using cancer-targeted near infrared (NIR) fluorescent probes, offers the promise of accurate tumor delineation during surgeries and the detection of cancer specific molecular expression in vivo. However, nonspecific probe accumulation in normal tissue results in poor tumor fluorescence contrast, precluding widespread clinical adoption of novel imaging agents. Here we present the first clinical evidence that fluorescence lifetime (FLT) imaging can provide tumor specificity at the cellular level in patients systemically injected with panitumumab-IRDye800CW, an EGFR-targeted NIR fluorescent probe.

EXPERIMENTAL DESIGN

We performed wide-field and microscopic FLT imaging of resection specimens from patients injected with panitumumab-IRDye800CW under an FDA directed clinical trial.

RESULTS

We show that the FLT within EGFR-overexpressing cancer cells is significantly longer than the FLT of normal tissue, providing high sensitivity (>98%) and specificity (>98%) for tumor versus normal tissue classification, despite the presence of significant nonspecific probe accumulation. We further show microscopic evidence that the mean tissue FLT is spatially correlated (r > 0.85) with tumor-specific EGFR expression in tissue and is consistent across multiple patients. These tumor cell-specific FLT changes can be detected through thick biological tissue, allowing highly specific tumor detection and noninvasive monitoring of tumor EFGR expression in vivo.

CONCLUSIONS

Our data indicate that FLT imaging is a promising approach for enhancing tumor contrast using an antibody-targeted NIR probe with a proven safety profile in humans, suggesting a strong potential for clinical applications in image guided surgery, cancer diagnostics, and staging.

First-Line Biological Agents Plus Chemotherapy in Older Patients with Metastatic Colorectal Cancer: A Retrospective Pooled Analysis

BACKGROUND

Biologicals, in combination with chemotherapy, are recommended as first-line treatment of metastatic colorectal cancer (mCRC); however, evidence guiding the appropriate management of older patients with mCRC is limited.

OBJECTIVE

This study was undertaken to compare the efficacy and safety outcomes in older versus younger patients with mCRC who received first-line biological therapy.

METHODS

This retrospective analysis used pooled data from five trials undertaken by the Spanish Cooperative Group for the Treatment of Digestive Tumours. All were studies of adults with advanced CRC who received first-line treatment with chemotherapy plus bevacizumab, cetuximab or panitumumab, stratified by age (≥ 65 vs. < 65 years). Endpoints included progression-free survival (PFS), overall survival (OS), overall response rate (ORR) and safety.

RESULTS

In total, 999 patients from five studies were included in the analysis: 480 (48%) were aged ≥ 65 years, and 519 (52%) were aged < 65 years. Median PFS did not differ significantly between patients aged ≥ 65 and < 65 years (9.9 vs. 9.4 months; hazard ratio [HR] 1.01; 95% confidence interval [CI] 0.88-1.17). Median OS was significantly shorter in older than in younger patients (21.3 vs. 25.0 months; HR 1.21; 95% CI 1.04-1.41). There was no significant difference between older and younger patients in ORR (59 vs. 62%). Patients aged ≥ 65 years experienced significantly more treatment-related grade 3 or higher adverse events (61.67%) than did patients aged < 65 years (45.86%).

CONCLUSIONS

Biologicals plus chemotherapy is an effective first-line treatment option for selected patients aged ≥ 65 years with mCRC and has a manageable safety profile and efficacy comparable to that observed in younger patients.

Clinical and molecular characteristics and treatment outcomes of advanced right-colon, left-colon and rectal cancers: data from 1180 patients in a phase III trial of panitumumab with an extended biomarker panel

BACKGROUND

Primary tumour location (PTL) is being adopted by clinicians to guide treatment decisions in metastatic colorectal cancer (mCRC). Here we test PTL as a predictive marker for panitumumab efficacy, and examine its relationship with an extended biomarker profile. We also examine rectal tumours as a separate location.

PATIENTS AND METHODS

mCRC patients from the second-line PICCOLO trial of irinotecan versus irinotecan/panitumumab (IrPan). PTL was classified as right-PTL, left-PTL or rectal-PTL. PTL was assessed as a predictive biomarker for IrPan effect in RAS-wild-type (RAS-wt) patients (compared with irinotecan alone), then tested for independence alongside an extended biomarker profile (BRAF, epiregulin/amphiregulin (EREG/AREG) and HER3 mRNA expression).

RESULTS

PTL data were available for 1180 patients (98.5%), of whom 558 were RAS-wt. High HER3 expression was independently predictive of panitumumab overall survival improvement, but PTL and EREG/AREG were not. IrPan progression-free survival (PFS) improvement compared with irinotecan was seen in left-PTL [hazard ratio (HR) = 0.61, P = 0.002) but not right-PTL (HR = 0.98, P = 0.90) (interaction P = 0.05; RAS/BRAF-wt interaction P = 0.10), or in rectal-PTL (HR = 0.82, P = 0.20) (interaction P = 0.14 compared with left-PTL; RAS/BRAF-wt interaction P = 0.04). Patients with right-PTL and high EREG/AREG or HER3 expression, had IrPan PFS improvement (high EREG/AREG HR = 0.20, P = 0.04; high HER3 HR = 0.33, P = 0.10) compared with irinotecan. Similar effect was seen for rectal-PTL patients (high EREG/AREG HR = 0.44, P = 0.03; high HER3 HR = 0.34, P = 0.05).

CONCLUSIONS

RAS-wt patients with left-PTL are more likely to have panitumumab PFS advantage than those with right-PTL or rectal-PTL. However, an extended biomarker panel demonstrated significant heterogeneity in panitumumab PFS effect within a tumour location. AREG/EREG and HER3 mRNA expression identifies patients with right-PTL or rectal-PTL who achieve similar PFS effect with panitumumab as left-colon patients. Testing could provide a more reliable basis for clinical decision making. Further validation and development of these biomarkers is required to optimise routine patient care.

CLINICAL TRIAL REGISTRATION

ISRCTN identifier: ISRCTN93248876.

Efficacy and Safety of Modified FOLFOXIRI+α in the Treatment of Advanced and Recurrent Colorectal Cancer: A Single-center Experience

Objective In the treatment of advanced and recurrent colorectal cancer (ARCC), FOLFOXIRI regimens have been proven to be significantly superior to FOLFIRI in terms of the progression-free survival (PFS), response rate (RR), and overall survival (OS). Furthermore, the Tribe trial showed that the RR and PFS rates in patients who received bevacizumab (Bmab) +FOLFOXIRI were superior to those in patients treated with Bmab+FOLFIRI. A phase III trial of panitumumab (Pmab) +FOLFOXIRI is currently ongoing. A modified FOLFOXIRI regimen is also widely used to reduce adverse events. In our department, we introduced modified FOLFOXIRI+α (mFOLFOXIRI+α) in 2015. The present study reviewed the efficacy and safety of mFOLFOXIRI+α. Methods Eligible patients were retrospectively reviewed, and their results were compared to those of patients treated with other regimens (OTHERS) (n=134) to demonstrate the efficacy of this treatment. Patients: Between February 2015 and November 2018, 12 patients with ARCC (male/female=6/6; average age, 60.7 years old) received mFOLFOXIRI+α (Bmab: 10, Pmab: 1, alone: 1). Results The median PFS in the mFOLFOXIRI+α and OTHERS groups was 565 and 322 days, respectively (p=0.0544). The RR in the mFOLFOXIRI+α and OTHERS groups was 66.7% and 31.3%, respectively (p=0.0135). The conversion rate (Conv R) in the mFOLFOXIRI+α and OTHERS groups was 50.0% and 12.7%, respectively (p=0.0007). While 58% of patients treated with FOLFOXIRI+α developed grade ≥3 leukopenia, the incidence of febrile neutropenia (FN) was only 17%. In all patients with symptoms due to the tumor burden, the symptoms subsided with mFOLFOXIRI+α treatment. Conclusion Based on the RR, Conv R, and symptom palliation ability, mFOLFOXIRI+α was suggested to be a viable candidate for first-line treatment for patients with ARCC, especially those with a high tumor burden.

[Long-Term Effectiveness of Chemotherapy Containing mFOLFOX6 plus Panitumumab and 5-FU/l-LV plus Panitumumab after Primary Tumor Resection in a Case of Ascending Colon Carcinoma and Multiple Hepatic Metastases]

The patient was a 79-year-old man. He had ascending colon carcinoma and multiple hepatic metastases, and right hemicolectomy( D2)was performed in June 2012(SE, N1, P0, M1[H3], Stage Ⅳ). After surgery, 8 courses of mFOLFOX6 plus panitumumab biweekly, then, 5-FU/l-LV biweekly and panitumumab every 4 weeks were administered because he had wild- type KRAS. Before chemotherapy, his serum CEA level was 122 ng/mL, but the value decreased rapidly to a normal level after 7months. The hepatic metastases also decreased, and the lesion was only slightly observed on CT after 7months. Five years after the surgery, images and his CEA level are both normal, and the effectiveness is maintained. Even for right colon cancer, anti-EGFR antibodies might be effective if RAS is wild-type.

Eligibility of real-world patients with chemo-refractory, K-RAS wild-type, metastatic colorectal cancer for palliative intent regorafenib monotherapy

The CORRECT trial demonstrated survival benefits with regorafenib monotherapy in patients with treatment-refractory, metastatic colorectal cancer (mCRC). However, the trial's stringent eligibility criteria for regorafenib may limit its external validity. We aimed to examine treatment attrition rates and eligibility for regorafenib in routine practice. We identified patients at the British Columbia Cancer Agency diagnosed with mCRC who demonstrated disease progression or intolerable toxicity on 2 or more lines of systemic therapy. During the study timeframe, panitumumab and cetuximab were only used in the chemo-refractory setting. Data on clinicopathologic variables and patient outcomes were ascertained and analyzed. Eligibility was determined using the CORRECT trial criteria. A total of 391 patients were identified, among whom only 39% were eligible for regorafenib: 35% in the panitumumab group and 51% in the cetuximab group. The main reasons for ineligibility in all patients were Eastern Cooperative Oncology Group Performance Status (ECOG PS) > 1 (69%), an elevated total bilirubin (21%), and thromboembolic events in the past 6 months (10%). No difference in eligibility for regorafenib was observed between patients previously receiving panitumumab or cetuximab (P = 0.914; 95% CI 0.550-1.951). Kaplan-Meier analyses showed that regorafenib-eligible compared to regorafenib-ineligible patients had an increased median overall survival of 5.3 versus 2.1 months, respectively (P < 0.001). However, Cox proportional hazard analyses showed that only ECOG PS rather than trial eligibility was correlated with outcomes. The strict eligibility criteria disqualify most patients with treatment-refractory mCRC for regorafenib therapy. Future trials should broaden the eligibility criteria to improve external validity.

Anti-EGFR Therapy in Small Bowel Adenocarcinoma

Small bowel adenocarcinoma is a rare disease occurring 50–100‐fold less often than colorectal cancer. This commentary describes similarities and differences between the two diseases and related results of recent clinical trials.

FOLFOX plus anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) is an effective first-line treatment for patients with RAS-wild left-sided metastatic colorectal cancer: A meta-analysis

BACKGROUND

The efficacy of oxaliplatin-based chemotherapy combined with anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) remains controversial in metastatic colorectal cancer (mCRC). This meta-analysis aims to estimate the effect of adding panitumumab or cetuximab to oxaliplatin-based chemotherapy in RAS wild type mCRC patients for the first-line treatment. The primary tumor location is also considered into this meta-analysis.

METHODS

RCT studies were identified by a search of MEDLINE, EMBASE, Cochrane library to October 2017, supplemented by manually retrieving ASCO, ESMO conference abstracts. The pooled hazard ratio (HR) for progression-free survival (PFS) and overall survival (OS), and pooled odds ratios (OR) for the overall response rate (ORR) were calculated by Review Manager 5.3.

RESULTS

The results indicated that the addition of anti-EGFR mAbs to FOLFOX regimen in RAS wild-type mCRC patients for the first-line treatment resulted in considerable improvements in PFS (HR = 0.70; 95% confidence interval [CI]: 0.59-0.82; P < .0001), OS (HR = 0.79; 95%CI: 0.67-0.92; P = .003), and ORR (OR = 2.56; 95% CI: 1.77-3.70; P < .00001) compared with chemotherapy alone. However, in RAS/BRAF wild patients, no significant differences were observed when anti-EGFR mAb was added to FLOX or XELOX regimen compared with chemotherapy alone with regard to OS and PFS, whereas FOLFOX+anti-EGFR mAb showed a marked superior OS and PFS (OS, HR = 0.77; 95% CI: 0.61-0.98; P = .03; PFS, HR = 0.68; 95% CI: 0.57-0.82; P < .00001). A meta-analysis including TAILOR and PRIME study suggests that primary tumor location (PTL) predicted a survival benefit when adding the EGFR antibody to FOLFOX regimen in RAS-wild mCRC patients (OS, HR for left-sided: 0.71; 95% CI: 0.59-0.85; P = .0002 and HR for right-sided: 0.90; 95% CI: 0.65-1.25; P = .53). However, the HR for PFS and ORR still suggests a benefit from the addition of anti-EGFR mAb in right-sided mCRC patients.

CONCLUSION

So these results suggest anti-EGFR mAb and oxaliplatin are good partners in the FOLFOX regimen. The addition of EGFR antibody to FOLFOX markedly improved efficacy in RAS-wild patients with left-sided mCRC. In RAS/BRAF-wild patients, the efficacy is similar. For patients with right-sided tumor, a benefit showing a trendency in favor of anti-EGFR mAb can still seen. The molecular characteristics behind the tumor location need to be more explored urgently.

Colorectal cancer spheroid biobanks: multi-level approaches to drug sensitivity studies

Biobanking of molecularly characterized colorectal cancer stem cells (CSCs) generated from individual patients and growing as spheroids in defined serum-free media offer a fast, feasible, and multi-level approach for the screening of targeted therapies and drug resistance molecular studies. By combining in vitro and in vivo analyses of cetuximab efficacy with genetic data on an ongoing collection of stem cell-enriched spheroids, we describe the identification and preliminary characterization of microsatellite stable (MSS) CSCs that, despite the presence of the KRAS (G12D) mutation, display epidermal growth factor (EGF)-dependent growth and are strongly inhibited by anti-EGF-receptor (EGFR) treatment. In parallel, we detected an increased resistance to anti-EGFR therapy of microsatellite instable (MSI) CSC lines irrespective of KRAS mutational status. MSI CSC lines carried mutations in genes coding for proteins with a role in RAS and calcium signaling, highlighting the role of a genomically unstable context in determining anti-EGFR resistance. Altogether, these results argue for a multifactorial origin of anti-EGFR resistance that emerges as the effect of multiple events targeting direct and indirect regulators of the EGFR pathway. An improved understanding of key molecular determinants of sensitivity/resistance to EGFR inhibition will be instrumental to optimize the clinical efficacy of anti-EGFR agents, representing a further step towards personalized treatments.

Panitumumab-Conjugated and Platinum-Cored pH-Sensitive Apoferritin Nanocages for Colorectal Cancer-Targeted Therapy

Apoferritin (AF) is a natural nontoxic iron carrier and has a natural hollow structure that can be used to deliver small molecules. The surface of AF has many amine functional groups that can be modified to create targeted ligands. We loaded oxaliplatin onto AF, which was then used as a template to conjugate with panitumumab via a polyethylene glycol linker. The oxaliplatin-loaded AF conjugated with panitumumab (AFPO) was designed to specifically target cell lines expressing epidermal growth factor receptor (EGFR). AFPO efficiently released oxaliplatin and suppressed tumor cell growth. Furthermore, the novel AFPO nanocages showed significant inhibition and greater accumulation in tumor models with high EGFR expression in vivo. Our study revealed that combining panitumumab and oxaliplatin into one formulation (AFPO nanocage) could be a promising shortcut in clinical applications.

The PANDA study: a randomized phase II study of first-line FOLFOX plus panitumumab versus 5FU plus panitumumab in RAS and BRAF wild-type elderly metastatic colorectal cancer patients

BACKGROUND

Few data are available regarding the treatment of metastatic colorectal cancer elderly patients with anti-EGFR agents in combination with chemotherapy. FOLFOX plus panitumumab is a standard first-line option for RAS wild-type metastatic colorectal cancer. Slight adjustments in chemo-dosage are commonly applied in clinical practice to elderly patients, but those modified schedules have never been prospectively tested. Clinical definition of elderly (≥70 years old) patients that may deserve a more or less intensive combination therapy is still debated. Several geriatric screening tools have been developed to predict survival and risk of toxicity from treatment. Among those, the G8 screening tool has been tested in cancer patients showing the strongest prognostic value for overall survival, while the CRASH score can stratify patients according to an estimated risk of treatment-related toxicities.

METHODS

The PANDA study is a prospective, open-label, multicenter, randomized phase II trial of first-line therapy with panitumumab in combination with dose-adjusted FOLFOX or with 5-fluorouracil monotherapy, in previously untreated elderly patients (≥70 years) with RAS and BRAF wild-type unresectable metastatic colorectal cancer. RAS and BRAF analyses are centralized. Geriatric assessment by means of G8 and CRASH score is planned at baseline and G8 will be re-evaluated at disease progression. The primary endpoint is duration of progression-free survival in both arms. Secondary endpoints include prospective evaluation of the prognostic role of G8 score and the correlation of CRASH risk categories with toxicity.

DISCUSSION

The PANDA study aims at exploring safety and efficacy of panitumumab in combination with FOLFOX or with 5FU/LV in elderly patients affected by RAS and BRAF wild-type metastatic colorectal cancer, to identify the most promising treatment strategy in this setting. Additionally, this is the first trial in which the prognostic role of the G8 score will be prospectively evaluated. Results of this study will drive further experimental developments for one or both combinations.

TRIAL REGISTRATION

PANDA is registered at Clinicaltrials.gov : NCT02904031 , July 11, 2016. PANDA is registered at EudraCT-No.: 2015-003888-10, September 3, 2015.

Different Toxicity of Cetuximab and Panitumumab in Metastatic Colorectal Cancer Treatment: A Systematic Review and Meta-Analysis

BACKGROUND

Over the last few years only one large randomized phase III study has tried to prospectively assess the safety of cetuximab and panitumumab in a head-to-head comparison. Despite the similar overall toxicity profile, cetuximab and panitumumab retain peculiar safety characteristics that deserve to be deeply investigated.

METHODS

We conducted a systematic review for randomized trials in PubMed, the Cochrane Central Register of Controlled Trials, SCOPUS, Web of Science, and EMBASE using the terms ("cetuximab" or "panitumumab") AND ("colorectal cancer" OR "colorectal carcinoma"). Data of adverse events were aggregated to obtain pooled incidence rates of prespecified adverse events. Incidence of skin toxicities was the primary outcome. A χ2 test was used for comparisons of proportions and an odds ratio (OR) was calculated for comparison.

RESULTS

A total of 38 studies were included for analysis. Cetuximab was associated with fewer G3-4 skin toxicities (OR = 0.62, 95% CI 0.53-0.62; p < 0.001), slightly more frequent G3-4 acne-like rash (OR = 1.24, 95% CI 1.04-1.48; p = 0.04), and paronychia (OR 1.36, 95% CI 1.1-1.7), but fewer cases of skin fissures (OR = 0.64, 95% CI 0.44-0.93; p = 0.02) and pruritus (OR = 0.45, 95% CI 0.35-0.58; p < 0.001) than PANI.

CONCLUSIONS

In conclusion, this meta-analysis shows that cetuximab- and panitumumab-based chemotherapy have different toxicity profiles in terms of the rate of severe adverse events.

Evaluation of short-term effectiveness of eight targeted agents combined with chemotherapy for treating esophageal-gastric junction adenocarcinoma: A network meta-analysis

This study aimed to evaluate the short-term effectiveness of eight targeted agents (ramucirumab, bevacizumab, rilotumumab, panitumumab, cetuximab, trebananib, trastuzumab, matuzumab) plus chemotherapy in esophageal-gastric junction adenocarcinoma (EGJA) by a network meta-analysis (NMA). PubMed, Embase, and Cochrane Library databases were systematically retrieved for randomized clinical trials (RCTs) concerning targeted agents plus chemotherapy in the treatment of EGJA. This NMA combined both direct and indirect evidence to evaluate odds ratio (OR) and to draw the surface under the cumulative ranking curve (SUCRA). In total 11 RCTs with 3649 EGJA patients (1907 patients treated with targeted agents plus chemotherapy were regarded as the case group, and 1742 patients with placebo plus chemotherapy were assigned into the control group) were enrolled in this study. Targeted agents in terms of stable disease (SD), partial response (PR), disease control rate (DCR), and overall response ratio (ORR) with the SUCRA values of 0.838, 0.807, 0.934, and 0.793, respectively. Cetuximab and trastuzumab, with the SUCRA values of 0.884 and 0.758, came on top as the best outcomes for treating EGJA in terms of progressive disease (PD) and complete response (CR). Cluster analysis results indicated that ramucirumab plus chemotherapy might be the optimal treatment for EGJA. Our findings indicated that ramucirumab plus chemotherapy might be the optimal treatment for EGJA amongst the nine treatment regimens, which provided clinical guidance for clinicians in the treatment of EGJA.

Anti epidermal growth factor receptor therapy in small bowel adenocarcinoma: Case report and literature review

RATIONALE

Small bowel adenocarcinoma (SBA) is an uncommon gastrointestinal cancer, thus limited data about treatment for advanced disease are available. The lack of specific guidelines has justified the use of therapeutic protocols usually applied in advanced colorectal cancer. Few and preliminary data have suggested possible clinical benefit from the use of target therapy such as bevacizumab and cetuximab.

PATIENT CONCERNS

We present the case of a young woman who was admitted to the emergency department for acute abdominal pain, nausea, and vomiting related to a jejunal stenosis.

DIAGNOSES

An enteroscopy with jejunal biopsy showed poorly differentiated cancerous cells suggestive for primary intestinal cancer. There were no signs of metastatic disease at radiological evaluation. A jejunal resection was subsequently carried out and the diagnosis of mucinous adenocarcinoma of the jejunum was confirmed.

INTERVENTIONS

The computed tomography scan performed 1 month after surgery showed metastatic disease. Therefore, the patient received combined protocols of chemotherapy and either bevacizumab or the anti-epidermal growth factor receptor (EGFR) panitumumab.

OUTCOMES

A partial response (PR) was achieved with Folfox plus panitumumab and a maintenance therapy with panitumumab is being conducted with a mild toxicity and a progression free survival of 19 months since the beginning of panitumumab.

LESSONS

This is, to the best of our knowledge, the first report in the literature of a patient with SBA who has benefitted from panitumumab with an overall survival of 83 months.

Protein biomarkers predictive for response to anti-EGFR treatment in RAS wild-type metastatic colorectal carcinoma

BACKGROUND

Metastatic colorectal cancer (mCRC) patients with mutant KRAS or NRAS are ineligible for anti-epidermal growth factor receptor (anti-EGFR) therapy, as RAS mutations activate downstream pathways independently of EGFR and induce primary resistance. However, even among RAS wild-type (WT) patients, only a fraction responds to anti-EGFR therapy, suggesting that other mechanisms of resistance exist. We hypothesise that different (epi)genetic alterations can lead to primary anti-EGFR resistance and that the crucial end point is the activation of protein signalling pathways.

METHODS

We analysed the expression and activation of proteins involved in cell signalling, using reverse phase protein arrays, on a multicentre French cohort of RAS WT mCRC treated with anti-EGFR treatment.

RESULTS

We identify activated EGFR and HER3 as protein biomarkers predictive for better overall survival. Active EGFR signalling and downstream PI3K, but not MAPK, pathway activation are associated with response to anti-EGFR treatment. Left-sided mCRC displays active ErbB2/3 and Wnt pathways and a better response to anti-EGFR therapy compared to right-sided mCRC.

CONCLUSIONS

We identify active EGFR and PI3K signalling as a key factor for response to anti-EGFR treatment in mCRC and highlight the importance of developing these biomarkers in clinical practice for the selection of RAS WT mCRC patients that would benefit from anti-EGFR treatment.

[A Case of Cecal Cancer with Para-Aortic Lymph Node Metastasis and Peritoneum Dissemination Treated with Curative Resection after mFOLFOX6 plus Panitumumab Chemotherapy]

A 67-year-old woman was diagnosed with cecal cancer, para-aortic lymph node metastasis, peritoneum dissemination, and left breast cancer. We administered mFOLFOX6 plus panitumumab for cecal cancer and an aromatase inhibitor for her breast cancer. She received 7 courses of systemic chemotherapy and showed a partial response. She additionally received 5 courses of mFOLFOX6 plus panitumumab. We performed ileocecal resection, sigmoidectomy, right oophorectomy, dissection of the para-aortic lymph nodes, and peritoneal dissemination. The histopathological findings revealed adenocarcinoma, ypT3, ypN0, ycM0, ypStage II (therapeutic effect Grade 2). One month later, she underwent an enforced left breast segmental resection and sentinel lymph node biopsy(0/2). The results of the pathological examination indicated no residual cancers (therapeutic effect Grade 3). The patient is now in good health and was administered S-1 as an outpatient.

Neutral evolution of drug resistant colorectal cancer cell populations is independent of their KRAS status

Emergence of tumor resistance to an anti-cancer therapy directed against a putative target raises several questions including: (1) do mutations in the target/pathway confer resistance? (2) Are these mutations pre-existing? (3) What is the relative fitness of cells with/without the mutation? We addressed these questions in patients with metastatic colorectal cancer (mCRC). We conducted an exhaustive review of published data to establish a median doubling time for CRCs and stained a cohort of CRCs to document mitotic indices. We analyzed published data and our own data to calculate rates of growth (g) and regression (d, decay) of tumors in patients with CRC correlating these results with the detection of circulating MT-KRAS DNA. Additionally we estimated mathematically the caloric burden of such tumors using data on mitotic and apoptotic indices. We conclude outgrowth of cells harboring intrinsic or acquired MT-KRAS cannot explain resistance to anti-EGFR (epidermal growth factor receptor) antibodies. Rates of tumor growth with panitumumab are unaffected by presence/absence of MT-KRAS. While MT-KRAS cells may be resistant to anti-EGFR antibodies, WT-KRAS cells also rapidly bypass this blockade suggesting inherent resistance mechanisms are responsible and a neutral evolution model is most appropriate. Using the above clinical data on tumor doubling times and mitotic and apoptotic indices we estimated the caloric intake required to support tumor growth and suggest it may explain in part cancer-associated cachexia.

[Anti-EGFR Antibody Combination Chemotherapy Was Effective against Locally Advanced Ascending Colon Cancer as Well as a Recurrent Lesion - A Case Report]

Here we report a case in which a locally advanced ascending colon cancer was successfully treated with anti-EGFR immunotherapy combined with chemotherapy and curative resection, and recurrent cancer was treated with the same chemotherapy. A 71-year-old man was diagnosed with ascending colon cancer in our department. No distant metastasis was observed, but curative resection was considered impossible because of extensive local cancer invasion. Because a genetic analysis revealed the presence of the wild-type KRAS gene, 6 courses of mFOLFOX6 plus cetuximab were administered. A cPR was obtained and curative resection was performed. The final diagnosis was ypT3N1M0, ypStage III a colon cancer, and chemotherapy improved the cancer stage to Grade 1b. Six courses of FOLFOX6 were then administered, followed by observation. After 2 years 6 months, a tumor of approximately 5 cm in size was noted in the right buttock using surveillance CT and was diagnosed as recurrent colon cancer. We considered further curative resection difficult and therefore 6 courses of mFOLFOX6 plus panitumumab were administered, a cPR was obtained, and right hip tumor extirpation surgery was performed. These results suggest that chemotherapy combined with anti-EGFR antibody immunotherapy is effective in treating recurrent colon cancer.

Targeted Therapies in the Treatment of Colorectal Cancers

Background:

In solid organ malignancies, no tumor type has seen a greater impact from the development of novel targeted therapies in 2004 than metastatic colorectal cancer.

Methods:

We review the current progress to date with the use of monoclonal antibodies in colorectal cancer and look at newer therapies under investigation.

Results:

Two monoclonal antibodies received Food and Drug Administration approval in early 2004, both for the indication of advanced, metastatic colorectal cancer. A large, randomized, placebo-controlled study demonstrated that the addition of a monoclonal antibody to vascular endothelial growth factor, bevacizumab, led to a statistically significant improvement in overall survival, with tolerable additional toxicity. Chimeric monoclonal antibody therapy directed at the epidermal growth factor receptor was associated with radiographic responses in a significant minority of patients with irinotecan-refractory colon cancer in a randomized phase II study of patients with irinotecan-refractory disease.

Conclusions:

These dramatic successes have led to further clinical studies of targeted therapy in colorectal cancer, making it one of the most promising areas of cancer research.

Real-time monitoring of microdistribution of antibody-photon absorber conjugates during photoimmunotherapy in vivo

Photoimmunotherapy (PIT) is an emerging low side effect cancer therapy based on a monoclonal antibody (mAb) conjugated with a near-infrared (NIR) phthalocyanine dye IRDye 700DX. IR700 is fluorescent, can be used as an imaging agent, and also is phototoxic. It induces rapid cell death after exposure to NIR light. PIT induces highly selective cancer cell death, while leaving most of tumor blood vessels unharmed, leading to an effect called super-enhanced permeability and retention (SUPR). SUPR significantly improves the effectiveness of the anticancer drug. Currently, the therapeutic effects of PIT are monitored using the IR700 fluorescent signal based on macroscopic fluorescence reflectance imagery. This technique, however, lacks the resolution and depth information to reveal the intratumor heterogeneity of mAb-IR700 distribution. We applied a minimally invasive two-channel fluorescence fiber imaging system by combining the traditional fluorescence imaging microscope with two imaging fiber bundles (~0.85mm). This method monitored mAb-IR700 distribution and therapeutic effects during PIT at different intratumor locations (e.g., tumor surface vs. deep tumor) in situ and in real time simultaneously. This enabled evaluation of the therapeutic effects in vivo and treatment regimens. The average IR700 fluorescence intensity recovery after PIT to the tumor surface is 91.50%, while it is 100.63% in deep tumors. To verify the results, two-photon microscopy combined with a microprism was also used to record the mAb-IR700 distribution and fluorescence intensity of green fluorescent protein (GFP) at different tumor depths during PIT. After PIT treatment, there was significantly higher IR700 fluorescence recovery in deep tumor than in the tumor surface. This phenomenon can be explained by increased vascular permeability immediately after NIR-PIT. Fluorescence intensity of GFP at the tumor surface decreased significantly more compared to that of deep tumor and in controls (no PIT).

Final analysis of the randomised PEAK trial: overall survival and tumour responses during first-line treatment with mFOLFOX6 plus either panitumumab or bevacizumab in patients with metastatic colorectal carcinoma

PURPOSE

To report planned final overall (OS) and progression-free survival (PFS) analyses from the phase II PEAK trial (NCT00819780).

METHODS

Patients with previously untreated, KRAS exon 2 wild-type (WT) metastatic colorectal cancer (mCRC) were randomised to mFOLFOX6 plus panitumumab or bevacizumab. The primary endpoint was PFS; secondary endpoints included OS, objective response rate, duration of response (DoR), time to response, resection and safety. Treatment effect by tumour RAS status was a prespecified objective. Exploratory analyses included early tumour shrinkage (ETS) and depth of response (DpR).

RESULTS

One hundred seventy patients had RAS WT and 156 had RAS WT/BRAF WT mCRC. Median PFS was longer for panitumumab versus bevacizumab in the RAS WT (12.8 vs 10.1 months; hazard ratio (HR) = 0.68 [95% confidence intervals (CI) = 0.48-0.96]; p = 0.029) and RAS WT/BRAF WT (13.1 vs 10.1 months; HR = 0.61 [95% CI = 0.42-0.88]; p = 0.0075) populations. Median OS (68% OS events) for panitumumab versus bevacizumab was 36.9 versus 28.9 months (HR = 0.76 [95% CI = 0.53-1.11]; p = 0.15) and 41.3 versus 28.9 months (HR = 0.70 [95% CI = 0.48-1.04]; p = 0.08), in the RAS WT and RAS WT/BRAF WT populations, respectively. Median DoR (11.4 vs 9.0 months; HR = 0.59 [95% CI = 0.39-0.88]; p = 0.011) and DpR (65.0 vs 46.3%; p = 0.0018) were improved in the panitumumab group. More panitumumab patients experienced ≥30% ETS at week 8 (64 vs 45%; p = 0.052); ETS was associated with improved PFS/OS. No new safety signals occurred.

CONCLUSIONS

First-line panitumumab + mFOLFOX6 increases PFS versus bevacizumab + mFOLFOX6 in patients with RAS WT mCRC.

BRAF Mutations as Predictive Biomarker for Response to Anti-EGFR Monoclonal Antibodies

Recently, the American Society of Clinical Oncology (ASCO) and the European Society for Medical Oncology (ESMO) recommended that patients with epidermal growth factor receptor (EGFR)-expressing metastatic colorectal cancer could be treated with anti-EGFR monoclonal antibodies (mAbs) cetuximab and panitumumab only in absence of Rat-Sarcoma (RAS) mutations. In addition to the previously established biomarker Kirsten rat sarcoma viral oncogene homolog (KRAS) exon 2, cumulative evidence also shows that patients whose tumors harbor KRAS exons 3 or 4 and neuroblastoma rat-sarcoma viral oncogene homolog (NRAS) exons 2, 3, and 4 mutations are found unlikely to benefit from anti-EGFR treatment.In line with the resistance of RAS mutated (mt) tumors, treatment response in BRAFmt tumors may also be altered given their important role in the EGFR signaling pathway. However, BRAF is not recommended as predictive biomarker yet because the evidence for the impact of BRAF mutations on treatment outcome is considered insufficient.This article summarizes the evidence for the impact of BRAF mutations on treatment outcome of anti-EGFR mAbs. Based on a review of literature, eight meta-analyses were included that consistently show that patients with BRAF mutations have a lack of treatment benefit of anti-EGFR mAbs. After discussing the quality and quantity of available evidence, we conclude that evidence is stronger than suggested by ESMO and ASCO. Additionally, we highlight that the quality of evidence for BRAF is even higher than for extended RAS as a biomarker. We therefore advise ESMO and ASCO to reconsider BRAF status as a predictive biomarker for response.

IMPLICATIONS FOR PRACTICE

In metastatic colorectal cancer (mCRC), therapy with anti-epidermal growth factor receptor (EGFR) monoclonal antibodies cetuximab and panitumumab is indicated in absence of RAS mutations. Cumulative evidence shows that patients with BRAF mutations, who comprise 10% of the mCRC population, do not benefit from anti-EGFR-antibody treatment. Although guidelines state that evidence for BRAF as a predictive marker is insufficient, we highlight that the quality and quantity of evidence is higher than suggested. We therefore encourage the use of BRAF as a predictive marker in order to exclude patients from therapy for whom limited treatment benefit is expected.

Multicenter Phase II Study of Panitumumab in Platinum Pretreated, Advanced Head and Neck Squamous Cell Cancer

Lessons Learned.

Panitumumab shows activity in terms of disease control rate and preventing disease progression but not for tumor shrinkage in head and neck squamous cell cancer for second‐line treatment. Epidermal growth factor receptor (EGFR) copy number gain, a property of tumor cells that theoretically could identify patients more likely to experience disease response, was common among patients having disease control.

Our trial, given the lower toxicity with an every‐2‐week schedule, provides guidance for future trials, for example, in combinations of immune therapies and anti‐EGFR‐antibodies.

Background.

The objective of this study was to investigate the efficacy and safety of panitumumab (anti‐epidermal growth factor receptor [EGFR] antibody) given as a single agent in platinum‐pretreated head and neck squamous cell cancer (HNSCC).

Methods.

Patients with advanced HNSCC previously treated with platinum‐containing therapy were included. Panitumumab was administered intravenously every 2 weeks at a dose of 6 mg/kg. Primary endpoint was overall response rate (ORR) according to Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1; secondary endpoints were progression‐free survival (PFS) and safety. A Simon's two‐step design was chosen; 4 partial remissions (PR) in the first 32 patients were required for continuing to step two. An exploratory biomarker analysis was performed.

Results.

Thirty‐three patients were enrolled. Two patients obtained a PR for an ORR of 6%, and 15 (45%) showed stable disease (SD) for at least 2 months, resulting in a 51% disease control rate. Median PFS was 2.6 months (95% confidence interval [CI]: 1.7–3.7), while median OS was 9.7 months (95% CI: 6.3–17.2). The most frequent adverse drug reactions were cutaneous rash (64%) and hypomagnesemia (55%). Overall, 30% of patients experienced grade 3/4 adverse events. No infusion‐related reactions occurred. EGFR copy number gain (CNG) was more frequent in patients who benefitted from panitumumab. Two uncommon KRAS mutations (G48E, T50I) and 3 canonical PIK3CA mutations (all E545K) were detected. High‐risk HPV16 was found in 10 patients and EGFR CNG in 13 treated patients. EGFR CNG seems to be more frequent in individuals with at least SD compared with patients with progressive disease (59% vs. 30%). PFS for patients with EGFR CNG was 4.6 months (95% CI: 1.0–9.2 months) and 1.9 months (95% CI: 1.0–3.2 months) for patients without CNG (p = .02).

Conclusion.

Panitumumab monotherapy in pretreated HNSCC patients was well tolerated but moderately active. We observed a considerable disease control rate. Future strategies with this agent comprise right patient selection through the identification of reliable biomarkers and gene signatures predicting response and, considering good tolerability and convenience, combination strategies with novel agents and immune therapeutic agents.

Cost-effectiveness analysis in the Spanish setting of the PEAK trial of panitumumab plus mFOLFOX6 compared with bevacizumab plus mFOLFOX6 for first-line treatment of patients with wild-type RAS metastatic colorectal cancer

OBJECTIVE

To assess the cost-effectiveness of panitumumab in combination with mFOLFOX6 (oxaliplatin, 5-fluorouracil, and leucovorin) vs bevacizumab in combination with mFOLFOX6 as first-line treatment of patients with wild-type RAS metastatic colorectal cancer (mCRC) in Spain.

METHODS

A semi-Markov model was developed including the following health states: Progression free; Progressive disease: Treat with best supportive care; Progressive disease: Treat with subsequent active therapy; Attempted resection of metastases; Disease free after metastases resection; Progressive disease: after resection and relapse; and Death. Parametric survival analyses of patient-level progression free survival and overall survival data from the PEAK Phase II clinical trial were used to estimate health state transitions. Additional data from the PEAK trial were considered for the dose and duration of therapy, the use of subsequent therapy, the occurrence of adverse events, and the incidence and probability of time to metastasis resection. Utility weightings were calculated from patient-level data from panitumumab trials evaluating first-, second-, and third-line treatments. The study was performed from the Spanish National Health System (NHS) perspective including only direct costs. A life-time horizon was applied. Probabilistic sensitivity analyses and scenario sensitivity analyses were performed to assess the robustness of the model.

RESULTS

Based on the PEAK trial, which demonstrated greater efficacy of panitumumab vs bevacizumab, both in combination with mFOLFOX6 first-line in wild-type RAS mCRC patients, the estimated incremental cost per life-year gained was €16,567 and the estimated incremental cost per quality-adjusted life year gained was €22,794. The sensitivity analyses showed the model was robust to alternative parameters and assumptions.

LIMITATIONS

The analysis was based on a simulation model and, therefore, the results should be interpreted cautiously.

CONCLUSIONS

Based on the PEAK Phase II clinical trial and taking into account Spanish costs, the results of the analysis showed that first-line treatment of mCRC with panitumumab + mFOLFOX6 could be considered a cost-effective option compared with bevacizumab + mFOLFOX6 for the Spanish NHS.

Left Versus Right: Does Location Matter for Refractory Metastatic Colorectal Cancer Patients in Phase 1 Clinical Trials?

PURPOSE

Location of the primary tumor is prognostic and predictive of efficacy with VEGF-inhibitors (I) versus EGFR-I given first-line to metastatic colorectal cancer (mCRC) patients. However, little is known regarding the effect of location on prognosis and prediction in refractory mCRC. We assessed the efficacy of VEGF-I and EGFR-I in regards to location of the primary tumor in patients with refractory mCRC enrolled in early phase studies.

METHODS

A historical cohort analysis of mCRC patients, including 44 phase I trials our institution, from March 2004 to September 2012. Median Progression free survival (mPFS) and overall survival (mOS) were estimated from Kaplan-Meier curves and groups were statistically compared with the log-rank test.

RESULTS

One hundred thirty-nine patients with a median age 59 (33-81). 73.9% received 3+ lines of therapy. All KRAS wild-type patients had received prior EGFR-I.

LOCATION

right 20.9%, left 61.9%, and transverse 4.3%. For survival analysis, transverse CRC were included with right. Of the 112 patients, mOS was left (N = 80) 6.6 months versus right (N = 32) 5.9 months, P = 0.18. mPFS was left (n = 86) 2.0 months versus right (N = 35) 2.0 months, P = 0.76. In subgroup analysis, survival was significant for KRAS wild-type patients with left-sided mCRC had mOS of 6.2 months with other agents versus 9.4 months with EGFR-I (P = 0.03).

CONCLUSIONS

In phase 1 clinical trials, although location alone was not prognostic in heavily pretreated patients, left-sided mCRC had improved survival with EGFR-I. Despite progression on EGFR-I, left-sided KRAS wild mCRC patients should be considered for phase 1 studies of agents targeting growth factor pathways.

Cost-effectiveness of cetuximab and panitumumab for chemotherapy-refractory metastatic colorectal cancer

Background

Cetuximab and panitumumab are monoclonal antibodies targeting the epidermal growth factor receptor. Both drugs are active against RAS wild type metastatic colorectal cancer after chemotherapy failure, with similar efficacy and toxicity profiles. However, their cost and limited survival benefits may compromise incorporation in the Brazilian public healthcare system, the Unified Heath System (Sistema Único de Saúde) (SUS).

Methods

A cost-effectiveness analysis was conducted using a Markov model from the Brazilian Public health perspective and a lifetime horizon in patients with RAS -wt mCRC. Transition probabilities and mortality rates were extracted from randomized studies. Treatment costs were obtained from price tables regulated by the Brazilian Health Ministry. The World Health Organization recommendation of three times GDP per capita was used to define the cost-effectiveness threshold.

Results

The use of cetuximab or panitumumab for chemotherapy-refractory mCRC patients resulted in 0.22 additional life-years relative to BSC, with incremental cost-effectiveness ratios (ICERs) of $58,240 and $52,772 per LY, respectively. That exceeds the pre-specified threshold for cost-effectiveness. Acquisition of biological agents was the major driver of increased costs.

Conclusions

Our economic evaluation demonstrates that both cetuximab and panitumumab are not a cost-effective approach in RAS-wt mCRC patients. Discussion about drug price should be prioritized to enable incorporation of these monoclonal antibodies in the SUS.

Brigatinib combined with anti-EGFR antibody overcomes osimertinib resistance in EGFR-mutated non-small-cell lung cancer

Osimertinib has been demonstrated to overcome the epidermal growth factor receptor (EGFR)-T790M, the most relevant acquired resistance to first-generation EGFR-tyrosine kinase inhibitors (EGFR-TKIs). However, the C797S mutation, which impairs the covalent binding between the cysteine residue at position 797 of EGFR and osimertinib, induces resistance to osimertinib. Currently, there are no effective therapeutic strategies to overcome the C797S/T790M/activating-mutation (triple-mutation)-mediated EGFR-TKI resistance. In the present study, we identify brigatinib to be effective against triple-mutation-harbouring cells in vitro and in vivo. Our original computational simulation demonstrates that brigatinib fits into the ATP-binding pocket of triple-mutant EGFR. The structure-activity relationship analysis reveals the key component in brigatinib to inhibit the triple-mutant EGFR. The efficacy of brigatinib is enhanced markedly by combination with anti-EGFR antibody because of the decrease of surface and total EGFR expression. Thus, the combination therapy of brigatinib with anti-EGFR antibody is a powerful candidate to overcome triple-mutant EGFR.

New Guideline on Managing Colorectal Cancer

A multidisciplinary panel of experts has issued guidelines that consolidate current evidence on testing for molecular biomarkers in colorectal cancer. The guidelines aim to standardize molecular testing for patients with colorectal cancer and help clinicians identify patients most likely to benefit from targeted treatments.