Radiofrequency ablation for autonomously functioning nodules as treatment for hyperthyroidism: subgroup analysis of toxic adenoma and multinodular goitre and predictors for treatment success.

PURPOSE: Treatment of hyperthyroidism caused by autonomously functioning thyroid nodules (AFTN) with 131I often leads to undesirable hypothyroidism. Radiofrequency ablation (RFA) has emerged as a promising alternative. This retrospective analysis aimed to examine the efficacy of, and postprocedural hypothyroidism after, RFA for AFTN. METHODS: Patients with hyperthyroidism caused by AFTN and treated with RFA were included if follow-up of at least 1 year was available. Cure was defined as thyroid medication-free biochemical euthyroidism. To predict cure, patient and treatment factors were analysed. A distinction was made between solitary toxic adenoma (STA) and toxic multinodular goitre (TMG). RESULTS: Forty-eight patients (36 STA, 12 TMG) were included. One year post-RFA cure rate was 72% in STA versus 25% in TMG (p = 0.004). One patient developed hypothyroidism. In 11 patients that remained hyperthyroid, a second RFA was successful in 83% of STA and 40% of TMG patients. At last available follow-up, this amounted to a total cure rate of 81% in STA and 33% in TMG (p = 0.002). In STA, cured patients had a higher baseline TSH and a lower FT3 than non-cured patients (p = 0.026 and 0.031). Cure was observed in 91% of patients when > 2.1 kJ/mL was delivered during RFA, compared to 44% when less energy was administered. CONCLUSION: The efficacy of RFA was nearly 3 times higher in STA patients compared to TMG. Severity of hyperthyroidism and kJ/mL delivered during RFA predicts cure. Direct comparison to the current standard of care is needed to implement RFA in treatment of hyperthyroidism caused by AFTN.

Biology-guided precision medicine in rare cancers: Lessons from sarcomas and neuroendocrine tumours.

Rare cancers, which collectively account for almost 25 % of all malignancies, are poorly understood in terms of their aetiology and pathogenesis and are infrequently the focus of translational and clinical research to improve their diagnosis and treatment. Consequently, those affected have comparatively few treatment options, and their prognosis is worse than that of patients with more common entities. Here we review two relevant groups of rare cancers, bone and soft-tissue sarcomas and neuroendocrine tumours (NET), to illustrate recent efforts towards individualised, biology-guided clinical management to improve long-term outcomes. Specifically, we address how comprehensive, multi-layered molecular analyses, including the assessment of predisposing hereditary factors, and innovative imaging approaches can improve the diagnosis of these diseases, allow for better prognostic assessment, and provide new targets for pharmacologic and, in the case of NET, nuclear medicine interventions, whose clinical value must be determined in controlled trials optimally tailored to the particular patient population most likely to benefit. Furthermore, we describe the importance of multidisciplinary collaboration in dedicated reference centres for rare cancers and the increasingly acknowledged potential of networking across institutions at a national and international level. Finally, we illustrate the value of a learning health system based on the systematic collection and sharing of the biological and clinical profiles of patients with rare cancers to achieve continuous cross-fertilisation of scientific and clinical efforts, making the vision of stratified precision medicine in these long-overlooked diseases a reality.

Correction to: [89Zr]Zr-cetuximab PET/CT as biomarker for cetuximab monotherapy in patients with RAS wild-type advanced colorectal cancer.

Missing Electronic Supplementary Materials.

Imaging angiogenesis in patients with head and neck squamous cell carcinomas by [68Ga]Ga-DOTA-E-[c(RGDfK)]2 PET/CT.

PURPOSE: Angiogenesis plays an important role in the growth and metastatic spread of solid tumours and is characterised by the expression of integrins on the cell surface of endothelial cells. Radiolabelled RGD peptides specifically target angiogenesis-related αvß3 integrins, expressed on the activated endothelial cells of sprouting blood vessels. Here, we validated the feasibility of 68Ga[Ga]-DOTA-E-[c(RGDfK)]2 (68Ga-RGD) PET/CT to visualise angiogenesis in patients with oral squamous cell carcinoma (OSCC). METHODS: Ten patients with OSCC and scheduled for surgical resection including elective neck dissection received an intravenously administration of 68Ga-RGD (42 ± 8 µg; 214 ± 9 MBq). All patients subsequently underwent dynamic (n = 5) or static PET/CT imaging (n = 5) for 60 min or for 4 min/bed position at 30, 60 and 90 min after injection, respectively. Quantitative tracer uptake in tumour lesions was expressed as standardised uptake values (SUV). Additionally, tumour tissue was immunohistochemically stained for αvß3 integrin to assess the expression pattern. RESULTS: 68Ga-RGD tumour accumulation was observed in all patients. At 60 min post injection, tumour SUVmax ranged between 4.0 and 12.7. Tracer accumulation in tumour tissue plateaued at 10 min after injection. Uptake in background tissue did not change over time, resulting in tumour-to-muscle tissue of 6.4 ± 0.7 at 60 min post injection. CONCLUSIONS: 68Ga-RGD PET/CT of αvß3 integrin expression in OSCC patients is feasible with adequate tumour-to-background ratios. It will provide more insight in angiogenesis as a hallmark of the head and neck squamous cell carcinomas' tumour microenvironment. TRIAL REGISTRATION: https://eudract.ema.europa.eu no. 2015-000917-31.

[89Zr]Zr-cetuximab PET/CT as biomarker for cetuximab monotherapy in patients with RAS wild-type advanced colorectal cancer.

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.

Clinical predictors of escalating care in hepatic and renal cyst infection in autosomal dominant polycystic kidney and liver disease.

BACKGROUND: Cyst infection may occur in autosomal dominant polycystic kidney disease (ADPKD) and autosomal dominant polycystic liver disease (ADPLD). Antimicrobial agents often fail to control infection, leading to invasive action. We aimed to identify factors predicting escalation of care. METHODS: ADPKD and ADPLD patients were identified from local/national databases (2001-2013). Records were screened for patients meeting criteria for cyst infection (positive cyst aspirate and/or clinical findings). Factors that predict escalated care were identified with multivariate modified Poisson regression. RESULTS: We screened 1773 patients. A total of 77 patients with cyst infection (4.3%) were included for analysis (hepatic 36%; male 49%; age 54 ±; 13 years; ADPKD 95%; dialysis 9%, diabetes 18%, renal transplant 56%, eGFR [IQR 24-78] ml/min/1.73 m2 (excluding patients with a history of renal transplant or receiving dialysis)). A pathogen was identified in 71% of cases. Escherichia coli was the most common pathogen and accounted for 69% of cases. Initial treatment was limited to antibiotics in 87% of patients (n = 67), 40% included a fluoroquinolone. Ultimately, 48% of patients underwent some form of invasive action (escalation of care). Increasing white blood cell count (WBC) (RR 1.04 95%-CI 1.01-1.07, p = 0.008) was associated with escalating care, whereas an increase in time between transplant and infection (RR 0.92 95% CI 0.86-0.97, p = 0.005) and E. coli isolation (RR 0.55 95% CI 0.34-0.89, p = 0.02) were protective. CONCLUSION: High serum WBC, isolation of atypical pathogens and early infection after transplantation are factors that increase the risk of escalation of care in hepatic and renal cyst infection patients.

ESMO consensus guidelines for the management of patients with metastatic colorectal cancer.

Colorectal cancer (CRC) is one of the most common malignancies in Western countries. Over the last 20 years, and the last decade in particular, the clinical outcome for patients with metastatic CRC (mCRC) has improved greatly due not only to an increase in the number of patients being referred for and undergoing surgical resection of their localised metastatic disease but also to a more strategic approach to the delivery of systemic therapy and an expansion in the use of ablative techniques. This reflects the increase in the number of patients that are being managed within a multidisciplinary team environment and specialist cancer centres, and the emergence over the same time period not only of improved imaging techniques but also prognostic and predictive molecular markers. Treatment decisions for patients with mCRC must be evidence-based. Thus, these ESMO consensus guidelines have been developed based on the current available evidence to provide a series of evidence-based recommendations to assist in the treatment and management of patients with mCRC in this rapidly evolving treatment setting.

A systematic review on [(18)F]FLT-PET uptake as a measure of treatment response in cancer patients.

Imaging biomarkers have a potential to depict the hallmarks of cancers that characterise cancer cells as compared to normal cells. One pertinent example is 3'-deoxy-3'-(18)F-fluorothymidine positron emission tomography ([(18)F]FLT-PET), which allows non-invasive in vivo assessment of tumour proliferation. Most importantly, [(18)F]FLT does not seem to be accumulating in inflammatory processes, as seen in [(18)F]-fludeoxyglucose, the most commonly used PET tracer for assessment of cell metabolism. [(18)F]FLT could therefore provide additional information about the tumour biology before, during and after treatment. This systematic review focuses on the use of [(18)F]FLT-PET tumour uptake values as a measure of tumour response to therapeutic interventions. The clinical studies which evaluated the role of [(18)F]FLT-PET as a measure of tumour response to treatment are summarised and the evidence linking [(18)F]FLT-PET tumour uptake values with clinical outcome is evaluated.

Molecular imaging as a tool to investigate heterogeneity of advanced HER2-positive breast cancer and to predict patient outcome under trastuzumab emtansine (T-DM1): the ZEPHIR trial.

BACKGROUND: Only human epidermal growth factor receptor (HER)2 status determined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) has been validated to predict efficacy of HER2-targeting antibody-drug-conjugate trastuzumab emtansine (T-DM1). We propose molecular imaging to explore intra-/interpatient heterogeneity in HER2 mapping of metastatic disease and to identify patients unlikely to benefit from T-DM1. PATIENTS AND METHODS: HER2-positive mBC patients with IHC3+ or FISH ≥ 2.2 scheduled for T-DM1 underwent a pretreatment HER2-positron emission tomography (PET)/computed tomography (CT) with (89)Zr-trastuzumab. [(18)F]2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT was performed at baseline and before T-DM1 cycle 2. Patients were grouped into four HER2-PET/CT patterns according to the proportion of FDG-avid tumor load showing relevant (89)Zr-trastuzumab uptake (>blood pool activity): patterns A and B were considered positive (>50% or all of the tumor load 'positive'); patterns C and D were considered negative (>50% or all of the tumor load 'negative'). Early FDG-PET/CT was defined as nonresponding when >50% of the tumor load showed no significant reduction of FDG uptake (<15%). Negative (NPV) and positive predictive values (PPV) of HER2-PET/CT, early FDG response and their combination were assessed to predict morphological response (RECIST 1.1) after three T-DM1 cycles and time-to-treatment failure (TTF). RESULTS: In the 56 patients analyzed, 29% had negative HER2-PET/CT while intrapatient heterogeneity (patterns B and C) was found in 46% of patients. Compared with RECIST1.1, respective NPV/PPV for HER2-PET/CT were 88%/72% and 83%/96% for early FDG-PET/CT. Combining HER2-PET/CT and FDG-PET/CT accurately predicted morphological response (PPV and NPV: 100%) and discriminated patients with a median TTF of only 2.8 months [n = 12, 95% confidence interval (CI) 1.4-7.6] from those with a TTF of 15 months (n = 25, 95% CI 9.7-not calculable). CONCLUSIONS: Pretreatment imaging of HER2 targeting, combined with early metabolic response assessment holds great promise for improving the understanding of tumor heterogeneity in mBC and for selecting patients who will/will not benefit from T-DM1. CLINICALTRIALSGOV IDENTIFIER: NCT01565200.

PET and SPECT imaging of a radiolabeled minigastrin analogue conjugated with DOTA, NOTA, and NODAGA and labeled with (64)Cu, (68)Ga, and (111)In.

Cholecystokinin-2 (CCK-2) receptors, overexpressed in cancer types such as small cell lung cancers (SCLC) and medullary thyroid carcinomas (MTC), may serve as targets for peptide receptor radionuclide imaging. A variety of CCK and gastrin analogues has been developed, but a major drawback is metabolic instability or high kidney uptake. The minigastrin analogue PP-F11 has previously been shown to be a promising peptide for imaging of CCK-2 receptor positive tumors and was therefore further evaluated. The peptide was conjugated with one of the macrocyclic chelators DOTA, NOTA, or NODAGA. The peptide conjugates were then radiolabeled with either (68)Ga, (64)Cu, or (111)In. All (radio)labeled compounds were evaluated in vitro (IC50) and in vivo (biodistribution and PET/CT and SPECT/CT imaging). IC50 values were in the low nanomolar range for all compounds (0.79-1.51 nM). In the biodistribution studies, (68)Ga- and (111)In-labeled peptides showed higher tumor-to-background ratios than the (64)Cu-labeled compounds. All tested radiolabeled compounds clearly visualized the CCK2 receptor positive tumor in PET or SPECT imaging. The chelator did not seem to affect in vivo behavior of the peptide for (111)In- and (68)Ga-labeled peptides. In contrast, the biodistribution of the (64)Cu-labeled peptides showed high uptake in the liver and in other organs, most likely caused by high blood levels, probably due to dissociation of (64)Cu from the chelator and subsequent transchelation to proteins. Based on the present study, (68)Ga-DOTA-PP-F11 might be a promising radiopharmaceutical for PET/CT imaging of CCK2 receptor expressing tumors such as MTC and SCLC. Clinical studies are warranted to investigate the potential of this tracer.

Targeted radionuclide and fluorescence dual-modality imaging of cancer: preclinical advances and clinical translation.

In oncology, sensitive and reliable detection tumor tissue is crucial to prevent recurrences and to improve surgical outcome. Currently, extensive research is focused on the use of radionuclides as well as fluorophores to provide real-time guidance during surgery to aid the surgeon in the identification of malignant tissue. Particularly, dual-modality approaches combining radionuclide and near-infrared fluorescence (NIRF) imaging have shown promising results in preclinical studies. Radionuclide imaging allows sensitive intra-operative localization of tumor lesions using a gamma probe, whereas NIRF imaging allows more accurate real-time tumor delineation. Consequently, both radionuclide and NIRF imaging might complement each other, and dual-modality image-guided surgery may overcome limitations of the currently used single-modality imaging techniques. In this review, a comprehensive overview on recent preclinical advances in tumor-targeted radionuclide and fluorescence dual-modality imaging is provided. Subsequently, the clinical applicability of dual-modality image-guided surgery is discussed.

Cost-effectiveness of FDG-PET/CT for cytologically indeterminate thyroid nodules: a decision analytic approach.

CONTEXT: Patients with thyroid nodules of indeterminate cytology undergo diagnostic surgery according to current guidelines. In 75% of patients, the nodule is benign. In these patients, surgery was unnecessary and unbeneficial because complications may occur. Preoperative fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) was found to have a very high negative predictive value (96%) and might therefore avoid futile surgery, complications, and costs. In the United States, two molecular tests of cytology material are routinely used for this purpose. OBJECTIVE: Five-year cost-effectiveness for routine implementation of FDG-PET/CT was evaluated in adult patients with indeterminate fine-needle aspiration cytology and compared with surgery in all patients and both molecular tests. DESIGN: A Markov decision model was developed to synthesize the evidence on cost-effectiveness about the four alternative strategies. The model was probabilistically analyzed. One-way sensitivity analyses of deterministic input variables likely to influence outcome were performed. SETTING AND SUBJECTS: The model was representative for adult patients with cytologically indeterminate thyroid nodules. MAIN OUTCOME MEASURES: The discounted incremental net monetary benefit (iNMB), the efficiency decision rule containing outcomes as quality-adjusted life-years and (direct) medical cost, of implementation of FDG-PET/CT is displayed. RESULTS: Full implementation of FDG-PET/CT resulted in 40% surgery for benign nodules, compared with 75% in the conventional approach, without a difference in recurrence free and overall survival. The FDG-PET/CT modality is the more efficient technology, with a mean iNMB of €3684 compared with surgery in all. Also, compared with a gene expression classifier test and a molecular marker panel, the mean iNMB of FDG-PET/CT was €1030 and €3851, respectively, and consequently the more efficient alternative. CONCLUSION: Full implementation of preoperative FDG-PET/CT in patients with indeterminate thyroid nodules could prevent up to 47% of current unnecessary surgery leading to lower costs and a modest increase of health-related quality of life. Compared with an approach with diagnostic surgery in all patients and both molecular tests, it is the least expensive alternative with similar effectiveness as the gene-expression classifier.

Monitoring hypoxia and vasculature during bevacizumab treatment in a murine colorectal cancer model.

The purpose of this study was to assess the effect of bevacizumab on vasculature and hypoxia in a colorectal tumor model. Nude mice with subcutaneous LS174T tumors were treated with bevacizumab or saline. To assess tumor properties, separate groups of mice were imaged using (18) F-Fluoromisonidazole (FMISO) and (18) F-Fluorodeoxyglucose (FDG) positron emission tomography or magnetic resonance imaging before and 2, 6 and 10 days after the start of treatment. Tumors were harvested after imaging to determine hypoxia and vascular density immunohistochemically. The T2 * time increased significantly less in the bevacizumab group. FMISO uptake increased more over time in the control group. Vessel density significantly decreased in the bevacizumab-treated group. The Carbonic anhydrase 9 (CAIX) and glucose uptake transporter 1 (GLUT1) fractions were higher in bevacizumab-treated tumors. However, the hypoxic fraction showed no significant difference. Bevacizumab led to shorter T2 * times and higher GLUT1 and CAIX expression, suggesting an increase in hypoxia and a higher glycolytic rate. This could be a mechanism of resistance to bevacizumab. The increase in hypoxia, however, could not be demonstrated by pimonidazole/FMISO, possibly because distribution of these tracers is hampered by bevacizumab-induced effects on vascular permeability and perfusion.

Anti-CEA antibody fragments labeled with [(18)F]AlF for PET imaging of CEA-expressing tumors.

A facile and rapid method to label peptides with (18)F based on chelation of [(18)F]AlF has been developed recently. Since this method requires heating to 100 °C, it cannot be used to label heat-sensitive proteins. Here, we used a two-step procedure to prepare (18)F-labeled heat-labile proteins using the [(18)F]AlF method based on hot maleimide conjugation. 1,4,7-Triazacyclononae-1,4-diacetate (NODA) containing a methyl phenylacetic acid group (MPA) functionalized with N-(2-aminoethyl)maleimide (EM) was used as a ligand which was labeled with [(18)F]AlF and then conjugated to the humanized anti-CEA antibody derivatives hMN-14-Fab', hMN-14-(scFv)2 (diabody), and a Dock-and-Lock engineered dimeric fragment hMN-14 Fab-AD2 at room temperature. The in vivo tumor targeting characteristics of the (18)F-labeled antibody derivatives were determined by PET imaging of mice with s.c. xenografts. NODA-MPAEM was radiolabeled with [(18)F]AlF at a specific activity of 29-39 MBq/nmol and a labeling efficiency of 94 ± 2%. The labeling efficiencies of the maleimide conjugation ranged from 70% to 77%, resulting in [(18)F]AlF-labeled hMN14-Fab', hMN14-Fab-AD2, or hMN14-diabody with a specific activity of 15-17 MBq/nmol. The radiolabeled conjugates were purified by gel filtration. For biodistribution and microPET imaging, antibody fragments were injected intravenously into BALB/c nude mice with s.c. CEA-expressing LS174T xenografts (right flank) and CEA-negative SK-RC-52 xenografts (left flank). All [(18)F]AlF-labeled conjugates showed specific uptake in the LS174T xenografts with a maximal tumor uptake of 4.73% ID/g at 4 h after injection. Uptake in CEA-negative SK-RC-52 xenografts was significantly lower. Tumors were clearly visualized on microPET images. Using a [(18)F]AlF-labeled maleimide functionalized chelator, antibody fragments could be radiofluorinated within 4 h at high specific activity. Here, we translated this method to preclinical PET imaging studies and showed feasibility of [(18)F]AlF-fluorinated hMN-14-Fab', [(18)F]AlF-hMN-14-Fab-AD2, and [(18)F]AlF-hMN-14-diabody for microPET imaging of CEA-expressing colonic cancer.

18F-FLT PET changes during radiotherapy combined with cetuximab in head and neck squamous cell carcinoma patients.

AIM: Early treatment response of head and neck cancer to radiotherapy concomitant with cetuximab was monitored by repetitive PET imaging with the proliferation tracer 18F-FLT. PATIENTS, METHODS: Five head and neck cancer patients, treated with radiotherapy and concomitant cetuximab following cetuximab induction, received four 18F-FLT PET-CT scans before and during treatment. Changes in SUVpeak, SUVmean and CT- and PET-segmented gross tumour volumes were evaluated, as were correlations with immunohistochemical staining for Epidermal Growth Factor Receptor (EGFR) and Ki-67 (proliferation marker) in pre-treatment tumour biopsies. RESULTS: 18F-FLT PET measured tumor responses to the induction dose of cetuximab varied from 43% SUVpeak decrease to 47% increase. After start of radiotherapy 18F-FLT PET parameters decreased significantly in all patients. No associations were found between PET parameters and EGFR or Ki-67 expression levels. CONCLUSION: Proliferation of head and neck carcinomas shows a varying response to cetuximab induction, but consistently decreases after addition of radiotherapy.

Tumor-receptor imaging in breast cancer: a tool for patient selection and response monitoring.

Breast cancer is a heterogeneous disease that can be subdivided into different groups, based on gene expression profiles or clinicopathological characteristics such as estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) expression. The expression of these receptors has both prognostic and predictive value. To improve breast cancer treatment, accurate methods for patient selection and response monitoring are required. One way to achieve this is by using molecular imaging, which can be used to measure the expression and accessibility of tumor-associated antigens in vivo, without the need of invasive biopsies. This review will focus on tumor-receptor imaging for currently approved targeted therapies and discuss the potential role of molecular imaging in the development of new therapeutic agents in breast cancer. Progress has been made in radionuclide imaging of ER, PR, HER2 and epidermal growth factor receptor (EGFR) expression, which can be used for treatment selection and response prediction to endocrine and other targeted therapy. Moreover, clinical studies have shown the feasibility for molecular imaging of the angiogenic pathway exploiting the expression of antigens closely associated with angiogenesis, such as αvß3 and VEGF. As proof of concept has been established, further research should be directed towards validation of the imaging methods and the impact on patient management.

Development of an imaging-guided CEA-pretargeted radionuclide treatment of advanced colorectal cancer: first clinical results.

BACKGROUND: Radiolabelled antibody targeting of cancer is limited by slow blood clearance. Pretargeting with a non-radiolabelled bispecific monoclonal antibody (bsMAb) followed by a rapidly clearing radiolabelled hapten peptide improves tumour localisation. The primary goals of this first pretargeting study in patients with the anti-CEACAM5 × anti-hapten (HSG) bsMAb, TF2, and the radiolabelled hapten-peptide, IMP288, were to assess optimal pretargeting conditions and safety in patients with metastatic colorectal cancer (CRC). METHODS: Different dose schedules were studied in four cohorts of five patients: (1) shortening the interval between the bsMAb and peptide administration (5 days vs 1 day), (2) escalating the TF2 dose (from 75 to 150 mg), and (3) reducing the peptide dose (from 100 to 25 µg). After confirmation of tumour targeting by (111)In-IMP288, patients were treated with a bsMAb/(177)Lu-IMP288 cycle. RESULTS: Rapid and selective tumour targeting of the radiolabelled peptide was visualised within 1 h, with high tumour-to-tissue ratios (>20 at 24 h). Improved tumour targeting was achieved with a 1-day interval between the administration of the bsMAb and the peptide and with the 25-µg peptide dose. High (177)Lu-IMP288 doses (2.5-7.4 GBq) were well tolerated, with some manageable TF2 infusion reactions, and transient grades 3-4 thrombocytopaenia in 10% of the patients who received (177)Lu-IMP288. CONCLUSION: This phase I study demonstrates for the first time that pretargeting with bsMAb TF2 and radiolabelled IMP288 in patients with CEA-expressing CRC is feasible and safe. With this pretargeting method, tumours are specifically and rapidly targeted.