89Zr-cetuximab PET imaging in patients with advanced colorectal cancer.
ABSTRACT: Monoclonal antibodies (mAbs) against the epidermal growth factor receptor (EGFR) are used in the treatment of advanced colorectal cancer (mCRC). Approximately 50% of patients benefit despite patient selection for RAS wild type (wt) tumors. Based on the hypothesis that tumor targeting is required for clinical benefit of anti-EGFR treatment, biodistribution and tumor uptake of (89)Zr-cetuximab by Positron Emission Tomography (PET), combining the sensitivity of PET with the specificity of cetuximab for EGFR was evaluated. Ten patients with wt K-RAS mCRC received 37 ± 1 MBq (89)Zr-cetuximab directly (<2 h) after the first therapeutic dose of cetuximab. PET-scans were performed from 1 hour to 10 days post injection (p.i.). Biodistribution was determined for blood and organs. Uptake in tumor lesions was quantified by Standardized Uptake Value (SUV) and related to response. In 6 of 10 patients (89)Zr-cetuximab uptake in tumor lesions was detected. Four of 6 patients with (89)Zr-cetuximab uptake had clinical benefit, while progressive disease was observed in 3 of 4 patients without (89)Zr-cetuximab uptake. Taken together, tumor uptake of 89Zr-cetuximab can be visualized by PET imaging. The strong relation between uptake and response warrants further clinical validation as an innovative selection method for cetuximab treatment in patients with wt RAS mCRC.
Project description:PURPOSE:One-third of patients with RAS wild-type mCRC do not benefit from anti-EGFR monoclonal antibodies. This might be a result of variable pharmacokinetics and insufficient tumor targeting. We evaluated cetuximab tumor accumulation on [89Zr]Zr-cetuximab PET/CT as a potential predictive biomarker and determinant for an escalating dosing strategy. PATIENTS AND METHODS:PET/CT imaging of [89Zr]Zr-cetuximab (37 MBq/10 mg) after a therapeutic pre-dose (500 mg/m2 ? 2 h) cetuximab was performed at the start of treatment. Patients without visual tumor uptake underwent dose escalation and a subsequent [89Zr]Zr-cetuximab PET/CT. Treatment benefit was defined as stable disease or response on CT scan evaluation after 8 weeks. RESULTS:Visual tumor uptake on [89Zr]Zr-cetuximab PET/CT was observed in 66% of 35 patients. There was no relationship between PET positivity and treatment benefit (52% versus 80% for PET-negative, P = 0.16), progression-free survival (3.6 versus 5.7 months, P = 0.15), or overall survival (7.1 versus 9.4 months, P = 0.29). However, in 67% of PET-negative patients, cetuximab dose escalation (750-1250 mg/m2) was applied, potentially influencing outcome in this group. None of the second [89Zr]Zr-cetuximab PET/CT was positive. Eighty percent of patients without visual tumor uptake had treatment benefit, making [89Zr]Zr-cetuximab PET/CT unsuitable as a predictive biomarker. Tumor SUVpeak did not correlate to changes in tumor size on CT (P = 0.23), treatment benefit, nor progression-free survival. Cetuximab pharmacokinetics were not related to treatment benefit. BRAF mutations, right-sidedness, and low sEGFR were correlated with intrinsic resistance to cetuximab. CONCLUSION:Tumor uptake on [89Zr]Zr-cetuximab PET/CT failed to predict treatment benefit in patients with RAS wild-type mCRC receiving cetuximab monotherapy. BRAF mutations, right-sidedness, and low sEGFR correlated with intrinsic resistance to cetuximab.
Project description:The aim of our study was to investigate whether microRNAs (miRNAs) could serve as predictive biomarkers to anti-EGFR therapy (cetuximab, panitumumab) in patients with RAS wild-type (wt-RAS) metastatic colorectal cancer (mCRC). Historical cohort of 93 patients with mCRC (2006-2009) was included and further divided into exploratory and validation cohorts. MiRNAs expression profiling was performed on the exploratory cohort of 41 wt-KRAS mCRC patients treated with cetuximab to identify miRNAs associated with time to progression (TTP). The validation was performed on two independent cohorts: 28 patients of wt-RAS mCRC treated with cetuximab and 24 patients of wt-RAS mCRC treated with panitumumab. We identified 9 miRNAs with significantly different expression between responders and non-responders to cetuximab therapy (P ? 0.01). These 9 miRNAs were further evaluated in two independent cohorts of patients and miR-31-3p (P < 0.001) and miR-31-5p (P < 0.001) were successfully confirmed as strongly associated with TTP in wt-RAS mCRC patients treated with cetuximab but not panitumumab. When evaluated on the complete cohort of cetuximab patients (N = 69), miR-31-3p (HR, 5.10; 95% CI, 2.52-10.32; P < 0.001) and miR-31-5p (HR, 4.80; 95% CI, 2.50-9.24; P < 0.001) were correlated with TTP on the comparable level of significance. There was no difference in miR-31-5p/3p expression levels in RAS mutated and wild-type tumor samples. MiR-31-5p/3p are promising predictive biomarkers of cetuximab response in wt-RAS mCRC patients.
Project description:BACKGROUND:At least 50% of triple negative breast cancer (TNBC) overexpress the epidermal growth factor receptor, EGFR, which paved the way for clinical trials investigating its blockade. Outcomes remained dismal stemming from mechanisms of resistance particularly the nuclear cycling of EGFR, which is enhanced by Src activation. Attenuation of Src reversed nuclear translocation, restoring EGFR to the cell surface. Herein, we hypothesize that changes in cellular distribution of EGFR upon Src inhibition with dasatinib can be annotated through the EGFR immunopositron emission tomography (immunoPET) radiotracer, [89Zr]Zr-cetuximab. METHODS:Nuclear and non-nuclear EGFR levels of dasatinib-treated vs. untreated MDA-MB-231 and MDA-MB-468 cells were analyzed via immunoblots. Both treated and untreated cells were exposed to [89Zr]Zr-cetuximab to assess binding at 4?°C and 37?°C. EGFR-positive MDA-MB-231, MDA-MB-468, and a patient-derived xenograft were treated with dasatinib or vehicle followed by cetuximab PET imaging to compare EGFR levels. After imaging, the treated mice were separated into two groups: one cohort continued with dasatinib with the addition of cetuximab while the other cohort received dasatinib alone. Correlations between the radiotracer uptake vs. changes in tumor growth and EGFR expression from immunoblots were analyzed. RESULTS:Treated cells displayed higher binding of [89Zr]Zr-cetuximab to the cell membrane at 4?°C and with greater internalized activity at 37?°C vs. untreated cells. In all tumor models, higher accumulation of the radiotracer in dasatinib-treated groups was observed compared to untreated tumors. Treated tumors displayed significantly decreased pSrc (Y416) with retained total Src levels compared to control. In MDA-MB-468 and PDX tumors, the analysis of cetuximab PET vs. changes in tumor volume showed an inverse relationship where high tracer uptake in the tumor demonstrated minimal tumor volume progression. Furthermore, combined cetuximab and dasatinib treatment showed better tumor regression compared to control and dasatinib-only-treated groups. No benefit was achieved in MDA-MB-231 xenografts with the addition of cetuximab, likely due to its KRAS-mutated status. CONCLUSIONS:Cetuximab PET can monitor effects of dasatinib on EGFR cellular distribution and potentially inform treatment response in wild-type KRAS TNBC.
Project description:PURPOSE Combining cetuximab with chemotherapy provides clinical benefit to 60% of the patients with RAS wild-type (RAS-wt) metastatic colorectal cancer (mCRC). This pilot study investigated the efficacy of cetuximab-based chemotherapy in a sample of patients (40%) with RAS mutation (RAS-mt) in their primary tumor whose circulating tumor DNA (ctDNA) was RAS-wt. MATERIALS AND METHODS The occurrence of Kirsten rat sarcoma viral oncogene homolog (KRAS), neuroblastoma rat sarcoma viral oncogene homolog (NRAS), V-raf murine sarcoma viral oncogene homolog B1 (BRAF), and PI3KCA mutations was determined in ctDNA by using a new ultrasensitive analysis based on mass spectrometry detection. All consenting patients with confirmed RAS-mt mCRC had disease progression on previous chemotherapy that contained no anti–epidermal growth factor receptor (EGFR). The patients with RAS-wt ctDNA received cetuximab + fluorouracil, leucovorin, and irinotecan (FOLFIRI), whereas those with RAS-mt ctDNA were treated with the oncologist’s choice of therapy. RESULTS Of 16 registered patients, 11 were male and five female. They were age 48 to 81 years, and they had unresectable metastatic adenocarcinoma from the colon (n = 11) or rectum (n = 5), with a median of two metastatic sites. They had received a median number of three previous chemotherapy protocols. Plasma genotyping identified RAS-mt in seven patients (44%) and RAS-wt in nine patients (56%). In the patients with wt ctDNA, objective tumor response rate was 50.0%, including one complete response and four partial responses after a median number of 6 courses of cetuximab + FOLFIRI (range, 1 to 16 courses). Two of the nine patients had stable disease, and two had progressive disease. No grade 3 to 4 toxicities were encountered. One-year survival rates were 60.0% for the patients with RAS-wt ctDNA and 17.9% for those with RAS-mt ctDNA. Median overall survival times were not reached and 4.7 months, respectively. CONCLUSION Patients with RAS-mt mCRC whose plasma biopsies contained RAS-wt could benefit from cetuximab-based therapy, a hypothesis to be tested in a prospective randomized trial.
Project description:Metastatic breast cancer is incurable. The goal of this study was to develop a positron emission tomography (PET)/near-infrared fluorescent (NIRF) probe for imaging CD105 expression in breast cancer experimental lung metastasis. TRC105, a chimeric anti-CD105 antibody, was dual-labeled with a NIRF dye (IRDye 800CW) and (89)Zr to yield (89)Zr-Df-TRC105-800CW. Luciferase-transfected 4T1 murine breast cancer cells were injected intravenously into female mice to establish the tumor model. Bioluminescence imaging (BLI) was carried out to noninvasively monitor the lung tumor burden. PET imaging revealed that 4T1 lung tumor uptake of (89)Zr-Df-TRC105-800CW was 8.7 ± 1.4, 10.9 ± 0.5, and 9.7 ± 1.1% ID/g at 4, 24, and 48 h postinjection (n = 4), with excellent tumor contrast. Biodistribution studies, blocking, control studies with (89)Zr-Df-cetuximab-800CW, ex vivo BLI/PET/NIRF imaging, and histology all confirmed CD105 specificity of the tracer. Broad clinical potential of TRC105-based agents was shown in many tumor types, which also enabled early detection of small metastasis and intraoperative guidance for tumor removal.
Project description:The anti-epidermal growth factor receptor (EGFR) monoclonal antibody cetuximab in combination with chemotherapy is a standard of care in the first-line treatment of RAS wild-type (wt) metastatic colorectal cancer (mCRC) and has demonstrated efficacy in later lines. Progressive disease (PD) occurs when tumours develop resistance to a therapy, although controversy remains about whether PD on a combination of chemotherapy and targeted agents implies resistance to both components. Here, we propose that some patients may gain additional clinical benefit from the reuse of cetuximab after having PD on regimens including cetuximab in an earlier treatment line. We conducted a non-systematic literature search in PubMed and reviewed published and ongoing clinical trials, focusing on later-line cetuximab reuse in patients with mCRC. Evidence from multiple studies suggests that cetuximab can be an efficacious and tolerable treatment when continued or when fit patients with mCRC are retreated with it after a break from anti-EGFR therapy. Furthermore, on the basis of available preclinical and clinical evidence, we propose that longitudinal monitoring of RAS status may identify patients suitable for such a strategy. Patients who experience progression on cetuximab plus chemotherapy but have maintained RAS wt tumour status may benefit from continuation of cetuximab with a chemotherapy backbone switch because they have probably developed resistance to the chemotherapeutic agents rather than the biologic component of the regimen. Conversely, patients whose disease progresses on cetuximab-based therapy due to drug-selected clonal expansion of RAS-mutant tumour cells may regain sensitivity to cetuximab following a defined break from anti-EGFR therapy. Looking to the future, we propose that RAS status determination at disease progression by liquid, needle or excisional biopsy may identify patients eligible for cetuximab continuation and rechallenge. With this approach, treatment benefit can be extended, adding to established continuum-of-care strategies in patients with mCRC.
Project description:We evaluated the ability of the PET imaging agent (89)Zr-trastuzumab to delineate HER2-positive gastric cancer and to monitor the pharmacodynamic effects of the epidermal growth factor receptor (EGFR)/human epidermal growth factor receptor 2 (HER2) tyrosine kinase inhibitor afatinib.Using (89)Zr-trastuzumab, (18)F-FDG, or 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT PET), we imaged HER2-positive NCI-N87 and HER2-negative MKN74 gastric cancer xenografts in mice. Next, we examined the pharmacodynamic effects of afatinib in NCI-N87 xenografts using (89)Zr-trastuzumab and (18)F-FDG PET and comparing imaging results to changes in tumor size and in protein expression as monitored by Western blot and histologic studies.Although (18)F-FDG uptake in NCI-N87 tumors did not change, a decrease in (89)Zr-trastuzumab uptake was observed in the afatinib-treated versus control groups (3.0 ± 0.0 percentage injected dose per gram (%ID/g) vs. 21.0 ± 3.4 %ID/g, respectively; P < 0.05). (89)Zr-trastuzumab PET results corresponded with tumor reduction, apoptosis, and downregulation of HER2 observed on treatment with afatinib. Downregulation of total HER2, phosphorylated (p)-HER2, and p-EGFR occurred within 24 h of the first dose of afatinib, with a sustained effect over 21 d of treatment.Afatinib demonstrated antitumor activity in HER2-positive gastric cancer in vivo. (89)Zr-trastuzumab PET specifically delineated HER2-positive gastric cancer and can be used to measure the pharmacodynamic effects of afatinib.
Project description:BACKGROUND:In the management of patients with RAS wild-type metastatic colorectal cancer (mCRC), anti-epidermal growth factor receptor (EGFR) therapies have demonstrated a clinical benefit, with longer survival. However, the correlation between the emergence of circulating RAS mutations and secondary resistance to anti-EGFR therapies requires further elucidation. In this study, we aim to examine evolutionary changes in RAS mutations through liquid biopsy in patients with mCRC during and after anti-EGFR therapy. METHODS:A total of 120 patients diagnosed with RAS wild-type mCRC will be enrolled in this study. Patients will receive a cetuximab-based infusional 5-fluorouracil regimen as first-line treatment. Cetuximab-based treatment is expected to continue until disease progression, intolerable toxic effects, or withdrawal of consent. Blood samples from enrolled patients will be collected before and then every 3?months during cetuximab-based treatment and also at disease progression. These blood samples will be evaluated for RAS resistance mutations by using the MassARRAY platform. The primary endpoint is the percentage of RAS mutations detected in circulating DNA from patients during cetuximab treatment. The correlation between the tumor response and survival outcomes of these patients and the emergence of circulating RAS mutations will be further analyzed. DISCUSSION:Liquid biopsy is a powerful technology that can represent tumor heterogeneity in a relatively noninvasive manner. Because RAS mutations play a major role in resistance to anti-EGFR therapy for mCRC, examining evolutionary changes in these mutations during such treatment through liquid biopsy would be useful. After comprehensively analyzing the emergence of circulating RAS mutations and its clinical relevance in this study, our results should provide practical guidance on anti-EGFR therapy for mCRC. TRIAL REGISTRATION:The date of trial registration ( NCT03401957 ) in this study was January 17, 2018.
Project description:Biomarkers predicting treatment response to the monoclonal antibody cetuximab in locally advanced head and neck squamous cell carcinomas (LAHNSCC) are lacking. We hypothesize that tumor accessibility is an important factor in treatment success of the EGFR targeting drug. We quantified uptake of cetuximab labeled with Zirconium-89 (89Zr) using PET/CT imaging.Seventeen patients with stage III-IV LAHNSCC received a loading dose unlabeled cetuximab, followed by 10 mg 54.5±9.6 MBq 89Zr-cetuximab. PET/CT images were acquired either 3 and 6 or 4 and 7 days post-injection. 89Zr-cetuximab uptake was quantified using standardized uptake value (SUV) and tumor-to-background ratio (TBR), and correlated to EGFR immunohistochemistry. TBR was compared between scan days to determine optimal timing.Uptake of 89Zr-cetuximab varied between patients (day 6-7: SUVpeak range 2.5-6.2). TBR increased significantly (49±28%, p < 0.01) between first (1.1±0.3) and second scan (1.7±0.6). Between groups with a low and high EGFR expression a significant difference in SUVmean (2.1 versus 3.0) and SUVpeak (3.2 versus 4.7) was found, however, not in TBR. Data is available at www.cancerdata.org (DOI: 10.17195/candat.2016.11.1).In conclusion, 89Zr-cetuximab PET imaging shows large inter-patient variety in LAHNSCC and provides additional information over FDG-PET and EGFR expression. Validation of the predictive value is recommended with scans acquired 6-7 days post-injection.
Project description:Anti-HER1 monoclonal antibody (mAb), panitumumab (Vectibix) is a fully human mAb approved by the FDA for the treatment of epidermal growth factor receptor (EGFR, HER1)-expressing colorectal cancers. By combining the targeted specificity of panitumumab with the quantitative in vivo imaging capabilities of PET, we evaluated the potential of (89)Zr-DFO-panitumumab PET/CT imaging and performed non-invasive, in vivo imaging of HER1 expression and estimated human dosimetry.Panitumumab was radiolabeled with (89)Zr using a derivative of desferrioxamine (DFO-Bz-NCS) and with (111)In using CHX-A" DTPA as bifunctional chelators. Comparative biodistribution/dosimetry of both radiotracers was performed in non-tumor bearing athymic nude mice (n=2 females and n=2 males) over 1-week following i.v. injection of either using (89)Zr-DFO-panitumumab or (111)In-CHX-A"-DTPA-panitumumab. Micro-PET/CT imaging of female athymic nude mice bearing human breast cancer tumors (n=5 per tumor group) with variable HER1-expression very low (BT-474), moderate (MDA-MB-231), and very high (MDA-MB-468) was performed at over 1 week following i.v. injection of (89)Zr-DFO-panitumumab.Radiochemical yield and purity of (89)Zr-Panitumumab was >70% and >98% respectively with specific activity 150 ± 10 MBq/mg of panitumumab in a ~4 hr synthesis time. Biodistribution of (111)In-CHX-A" DTPA -panitumumab and (89)Zr-DFO-panitumumab in athymic non-tumor bearing nude mice displayed similar percent injected dose per gram of tissue with prominent accumulation of both tracers in the lymph nodes, a known clearance mechanism of panitumumab. Also exhibited was prolonged blood pool with no evidence of targeted accumulation in any organ. Human radiation dose estimates showed similar biodistributions with estimated human effective doses of 0.578 and 0.183 mSv/MBq for (89)Zr-DFO-panitumumab and (111)In-CHX-A"-DTPA-panitumumab, respectively. Given the potential quantitative and image quality advantages of PET, imaging of tumor bearing mice was only performed using (89)Zr-DFO-panitumumab. Immuno-PET imaging of (89)Zr-DFO-panitumumab in mice bearing breast cancer xenograft tumors with variable HER1 expression showed high tumor uptake (SUV >7) in the MDA-MB-468 high HER1-expressing mice and a strong correlation between HER1-expression level and tumor uptake (R(2)= 0.857, P < .001).(89)Zr-DFO-panitumumab can prepared with high radiochemical purity and specific activity. (89)Zr-DFO-panitumumab microPET/CT showed uptake corresponding to HER-1 expression. Due to poor clearance, initial dosimetry estimates suggest that only a low dose (89)Zr-DFO-panitumumab shows favorable human dosimetry; however due to high tumor uptake, the use of (89)Zr-DFO-panitumumab is expected to be clinically feasible.