PURPOSE:The Belgian Precision initiative aims to implement tumor-agnostic next-generation sequencing (NGS) in patients with advanced cancer and expand genotype-matching drug availability. The present investigator-driven trial aimed to study the efficacy of afatinib in patients with advanced solid tumors harboring an activating HER2, EGFR, or HER3 mutation. PATIENTS AND METHODS:This open-label phase II trial has three cohorts: HER2-, EGFR-, and HER3-mutated previously treated solid tumors. The primary end point was objective response rate (ORR). For each cohort, a Simon two-stage design was used. Observation of ≥2 responses in the first 10 patients prompted a further 19 to be included. Secondary end points were disease control rate (DCR), duration of response (DOR), progression-free survival, overall survival, and safety. RESULTS:A total of 45 patients were included, with a median age of 62 years. For the HER2 cohort (n = 30), ORR was 3.3% (one partial response) and DCR was 23.3%. In the EGFR cohort, a total of seven patients were included, resulting in an ORR in 2/7 (28.6%) patients, with a DOR of 6.6 and 15.4 months. In the HER3 cohort, a total of eight patients were included, but none demonstrated an objective response. Safety data were consistent with the known safety profile of afatinib. CONCLUSION:The present phase II study, investigating afatinib in HER2-, EGFR-, orHER3-mutant pretreated solid tumors did not reach its primary end point in the HER2 cohort. Neither the EGFR nor the HER3 cohort reached full accrual, but clinically meaningful responses were observed in two EGFR-mutated patients. Further exploration of HER targeting in solid tumors is warranted.

Background Molecular diagnostics in oncology is shifting from targeted NGS panels to comprehensive genomic profiling (CGP), which detects a broader range of alterations and expands access to clinical trials and therapies. Method This study assessed the added value of CGP compared with current Belgian practice using local NGS panels covering a minimally required set of genes set by cancer type. We prospectively recruited 1000 patients with metastatic or locally advanced cancer across 13 Belgian hospitals. Tumor tissue or liquid biopsies were analyzed with FoundationOne CDx assays. The added value over reimbursed local NGS panels was measured by additional treatments recommendations issued by the national molecular tumor board (nMTB). Results CGP was successful in 93% of patients. Among patients tested with both local NGS and CGP, 48% received at least one additional nMTB recommendations based on CGP. Overall, CGP more than doubled targeted therapy recommendations compared with local NGS panels, with nMTB providing recommendations for 61% of patients. Of the evaluable patients (n=586), 23% received the nMTB recommended therapy. Non-adherence was due to treatment unavailability (25%), rapid clinical deterioration (24%), patient choice (17%), or physician decision (15%). Among those treated according to nMTB recommendations, the majority participated in clinical trials (48%), followed by standard of care treatments (35%) and off-label therapies (16%). Conclusions The GeNeo study demonstrated that CGP provides added clinical value by significantly increasing the detection of actionable alterations and targeted therapy recommendations compared with small reimbursed local NGS panels.

The Belgian Approach for Local Laboratory Extensive Tumor Testing (BALLETT) study assessed the feasibility of using comprehensive genomic profiling (CGP) in clinical decision-making for patients with advanced cancers. This multi-center study enrolled 872 patients from 12 Belgian hospitals. CGP was performed on tumor tissues using a standardized CGP panel (523 genes) across nine laboratories with success in 93% of patients and a median turnaround time of 29 days. Actionable genomic markers were identified in 81% of patients, substantially higher than the 21% using nationally reimbursed, small panels. A national molecular tumor board (nMTB) recommended treatments for 69% of patients, with 23% receiving matched therapies. Reasons for non-compliance were highly variable across clinical sites. Overall, BALLETT demonstrates the feasibility of implementing decentralized CGP and its potential to identify actionable targets in most patients with advanced cancers. BALLETT reinforces CGP’s utility and emphasizes the importance of collaboration, standardization, and addressing implementation challenges.

Human epidermal growth factor receptor 2 (HER2) status is used for decision-making in breast carcinoma treatment. The status is obtained through immunohistochemistry or in situ hybridization. These two methods have the disadvantage of necessitating tissue sampling, which is prone to error due to tumor heterogeneity or interobserver variability. Whole-body imaging might be a solution to map HER2 expression throughout the body. Methods: Twenty patients with locally advanced or metastatic breast carcinoma (5 HER2-positive and 15 HER2-negative patients) were included in this phase II trial to assess the repeatability of uptake quantification and the extended safety of the [68Ga]Ga-NOTA-anti-HER2 single-domain antibody (sdAb). The tracer was injected, followed by a PET/CT scan at 90 min. Within 8 d, the procedure was repeated. Blood samples were taken for antidrug antibody (ADA) assessment and liquid biopsies. On available tissues, immunohistochemistry, in situ hybridization, and mass spectrometry were performed to determine the correlation of HER2 status with uptake values measured on PET. If relevant preexisting [18F]FDG PET/CT images were available (performed as standard of care), a comparison was made. Results: With a repeatability coefficient of 21.8%, this imaging technique was repeatable. No clear correlation between PET/CT uptake values and pathology could be established, as even patients with low levels of HER2 expression showed moderate to high uptake. Comparison with [18F]FDG PET/CT in 16 patients demonstrated that in 7 patients, [68Ga]Ga-NOTA-anti-HER2 shows interlesional heterogeneity within the same patient, and [18F]FDG uptake did not show the same heterogeneous uptake in all patients. In some patients, the extent of disease was clearer with the [68Ga]Ga-NOTA-anti-HER2-sdAb. Sixteen adverse events were reported but all without a clear relationship to the tracer. Three patients with preexisting ADAs did not show adverse reactions. No new ADAs developed. Conclusion: [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT imaging shows similar repeatability to [18F]FDG. It is safe for clinical use. There is tracer uptake in cancer lesions, even in patients previously determined to be HER2-low or -negative. The tracer shows potential in the assessment of interlesional heterogeneity of HER2 expression. In a subset of patients, [68Ga]Ga-NOTA-anti-HER2-sdAb uptake was seen in lesions with no or low [18F]FDG uptake. These findings support further clinical development of [68Ga]Ga-NOTA-anti-HER2-sdAb as a PET/CT tracer in breast cancer patients.

Background Among the 10% of pancreatic cancers that occur in a familial context, around a third carry a pathogenic variant in a cancer predisposition gene. Genetic studies of pancreatic cancer predisposition are limited by high mortality rates amongst index patients and other affected family members. The genetic risk for pancreatic cancer is often shared with breast cancer susceptibility genes, most notably BRCA2, PALB2, ATM and BRCA1. Therefore, we hypothesized that additional shared genetic etiologies might be uncovered by studying families presenting with both breast and pancreatic cancer. Methods Focusing on a multigene panel of 276 DNA Damage Repair (DDR) genes, we performed next-generation sequencing in a cohort of 41 families with at least three breast cancer cases and one pancreatic cancer. When the index patient with pancreatic cancer was deceased, close relatives (first or second-degree) affected with breast cancer were tested (39 families). Results We identified 27 variants of uncertain significance in DDR genes. A splice site variant (c.1605 + 2T > A) in the RAD17 gene stood out, as a likely loss of function variant. RAD17 is a checkpoint protein that recruits the MRN (MRE11-RAD50-NBS1) complex to initiate DNA signaling, leading to DNA double-strand break repair. Conclusion Within families with breast and pancreatic cancer, we identified RAD17 as a novel candidate predisposition gene. Further genetic studies are warranted to better understand the potential pathogenic effect of RAD17 variants and in other DDR genes.

The increasing complexity of advanced-stage cancer management, coupled with the growing availability of targeted therapies, necessitates innovative approaches to treatment decision-making. The Belgian Approach for Local Laboratory Extensive Tumor Testing (BALLETT) study evaluated the feasibility and impact of implementing comprehensive genomic profiling (CGP) across multiple laboratories and integrating genomic data into clinical decision-making for patients with advanced cancers. This prospective, multi-center study enrolled 872 patients with advanced solid tumors across 12 Belgian hospitals. CGP was performed using a standardized next-generation sequencing panel across nine laboratories, with results reviewed by a national molecular tumor board (nMTB) for treatment recommendations. CGP was successfully performed in 93% of sequenced patients (756/814), with a median turnaround time from inclusion to nMTB report of 29 days. Actionable genomic markers were identified in 81% of patients, substantially higher than the estimated 23% if restricting to nationally reimbursed panels. The nMTB provided treatment recommendations for 69% of patients with successful CGP. Of those with recommendation uptake data available (n = 454), 23% received the matched treatment. Reasons for non-implementation included physician’s choice (27%), trial not conducted at an acceptable distance (21%), and rapid clinical deterioration (12%). CGP also revealed potential germline variants in 15% of cases, prompting recommendations for genetic counseling. The BALLETT study demonstrates the feasibility of implementing standardized CGP across multiple laboratories and its potential to identify actionable targets in a majority of patients with advanced cancers. However, the translation of genomic findings into clinical practice faces challenges, including drug access and the need for improved decision-support tools. These findings underscore the importance of addressing implementation barriers to fully realize the potential of precision oncology in routine clinical care.

The Belgian Precision initiative aims to maximize the implementation of tumor-agnostic NGS in patients with advanced cancer and enhance access to molecularly-guided treatment options (MGTOs). Academic tumor-agnostic basket phase 2 studies are part of this initiative. The current investigator-driven trial aimed to investigate olaparib efficacy in advanced cancers with a pathogenic or likely pathogenic mutation (germline or somatic) in a gene that plays a role in homologous recombination (HR). Open-label multi-cohort phase 2 study that examines the efficacy of olaparib in patients with an HR gene mutation in their tumor and failed SoC. Patients with a somatic or germline mutation in the same gene define a cohort. For each cohort, a Simon minimax two-stage design was used. If a response was observed in the first 13 patients, 14 additional patients were included (type I error rate of 5% and a power of 80% when the true response rate is 20%). Here, we report the results on four completed cohorts: patients with a BRCA1, BRCA2, CHEK2 or ATM mutation. The overall objective response rate across different tumor types was 11% in the BRCA1 (N=27) and 21% in the BRCA2 (N=27) mutated cohorts. Partial responses were seen in pancreatic cancer, gallbladder cancer, endocrine carcinoma of the pancreas and parathyroid cancer. One patient with a BRCA2 germline mutated colon cancer has an ongoing CR with 19+ months on treatment. mPFS in responding patients is 14+ months (5-34+ months). The clinical benefit rate was 63% in the BRCA1 and 46% in the BRCA2 mutated cohorts. No clinical activity was observed in the ATM (N=13) and CHEK2 (N=14) cohorts. Safety data were consistent with the known profile of olaparib. Olaparib showed efficacy in different cancer types harboring somatic or germline mutations in the BRCA1/2 genes but not in ATM and CHEK2. Patients with any cancer type harboring BRCA1/2 mutations should have access to olaparib with real-world documentation of efficacy in a retrospective register.

BRAF V600E is the key oncogenic driver mutation in hairy cell leukemia (HCL). We report the efficacy and safety of dabrafenib plus trametinib in patients with relapsed/refractory BRAF V600E mutation-positive HCL. This open-label, phase 2 study enrolled patients with BRAF V600E mutation-positive HCL refractory to first-line treatment with a purine analog or relapsed after >= 2 prior lines of treatment. Patients received dabrafenib 150 mg twice daily plus trametinib 2 mg once daily until disease progression, unacceptable toxicity, or death. The primary endpoint was investigator-assessed objective response rate (ORR) per criteria adapted from National Comprehensive Cancer Network-Consensus Resolution guidelines. Secondary endpoints included duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Fifty-five patients with BRAF V600E mutation-positive HCL were enrolled. The investigator-assessed ORR was 89.0% (95% confidence interval, 77.8%-95.9%); 65.5% of patients had a complete response (without minimal residual disease [MRD]: 9.1% [negative immunohistochemistry of bone marrow {BM} biopsy], 12.7% [negative BM aspirate flow cytometry {FC}], 16.4% [negative immunohistochemistry and/or FC results]; with MRD, 49.1%), and 23.6% had a partial response. The 24-month DOR was 97.7% with 24-month PFS and OS rates of 94.4% and 94.5%, respectively. The most common treatment-related adverse events were pyrexia (58.2%), chills (47.3%), and hyperglycemia (40.0%). Dabrafenib plus trametinib demonstrated durable responses with a manageable safety profile consistent with previous observations in other indications and should be considered as a rituximab-free therapeutic option for patients with relapsed/refractory BRAF V600E mutation-positive HCL. This trial is registered at www.clinicaltrials.gov as #NCT02034110.

Tyrosine kinase inhibitors (TKI) targeting the epidermal growth factor receptor (EGFR) have significantly prolonged survival in EGFR-mutant non-small cell lung cancer patients. However, the development of resistance mechanisms prohibits the curative potential of EGFR TKIs. Combination therapies emerge as a valuable approach to preventing or delaying disease progression. Here, we investigated the combined inhibition of polo-like kinase 1 (PLK1) and EGFR in TKI-sensitive EGFR-mutant NSCLC cells. The pharmacological inhibition of PLK1 destabilized EGFR levels and sensitized NSCLC cells to Osimertinib through induction of apoptosis. In addition, we found that c-Cbl, a ubiquitin ligase of EGFR, is a direct phosphorylation target of PLK1 and PLK1 impacts the stability of c-Cbl in a kinase-dependent manner. In conclusion, we describe a novel interaction between mutant EGFR and PLK1 that may be exploited in the clinic. Co-targeting PLK1 and EGFR may improve and prolong the clinical response to EGFR TKI in patients with an EGFR-mutated NSCLC.

The Belgian Precision initiative aims to implement tumor-agnostic NGS in advanced cancer patients (pts) and enhance access to genotype-matching drugs. The current study aimed to investigate the efficacy of afatinib in advanced pre-treated solid cancers with an EGFR (excluding non-small cell lung cancer (NSCLC)), HER2 or HER3 mutation. Open-label phase 2 study including 3 cohorts for previously treated advanced cancers: EGFR, HER2 and HER3 mutated. The primary endpoint for each cohort was objective response rate (ORR). Response assessment was performed every 8 weeks. For each cohort, a Simon two-stage design was used. The null hypothesis that the true ORR is 10%, was tested against a one-sided alternative that the true ORR is 30%. If two or more ORR were observed in the first ten pts, 19 additional pts were included (type I error 5% and power 80%) Secondary endpoints were disease control rate (DCR), duration of response (DOR), progression-free survival (PFS), overall survival (OS) and safety. A total of 45 pts were included in the trial with median age 62 years. The EGFR cohort comprised 7 pts: 2 pancreas, 1 head and neck, 1 breast, 1 endocrine tumor, 1 cervix and 1 kidney. The HER2 cohort comprised 30 pts: 11 NSCLC, 8 breast, 3 cervix, 2 colorectal, 2 head and neck, 1 bladder, 1 kidney, 1 liver and 1 pancreas. The HER3 cohort comprised 8 pts: 2 breast, 2 pancreas, 1 colorectal, 1 head and neck, 1 esophagus and 1 stomach. ORR and DCR were respectively 28.6% and 42.9% in the EGFR cohort, 3% and 49% in the HER2 cohort and 0% and 62.5% in the HER3 cohort. Partial responses were observed in a HER2-mutated NSCLC (1/11) with a DOR of 8.5 months, an EGFR-mutated breast cancer (1/1) with a DOR of 6.6 months and an EGFR-mutated pancreas cancer (1/2) with a DOR of 15.4 months. PFS and OS data will be presented at the meeting Safety data were consistent with the known safety profile of afatinib. Although three pts demonstrated a clinical meaningful benefit, afatinib did not result in a significant ORR improvement in the HER2 cohort, which completed accrual. Recruitment was hampered by a lack of systematic agnostic NGS sequencing and the COVID epidemic. Broader and more systematic agnostic NGS would enable further exploration of HER inhibition in solid tumors

Supplementary Table 1 - PDF file 57K, Supplementary Table 1. Details of platinum sensitivity and best response to olaparib and post-PARPi chemotherapy of the six patients whose tumor samples were analyzed by massively parallel sequencing. (NE: not evaluable)

Background: The Belgian Precision initiative aims to maximize the implementation of tumor-agnostic next-generation sequencing in patients with advanced cancer and enhance access to molecularly guided treatment options. Academic tumor-agnostic basket phase II studies are part of this initiative. The current investigator-driven trial aimed to investigate the efficacy of olaparib in advanced cancers with a (likely) pathogenic mutation (germline or somatic) in a gene that plays a role in homologous recombination (HR). Patients and methods: This open-label, multi-cohort, phase II study examines the efficacy of olaparib in patients with an HR gene mutation in their tumor and disease progression on standard of care.Patients with a somatic or germline mutation in the same gene define a cohort. For each cohort, a Simon minimax two-stage design was used. If a response was observed in the first 13 patients, 14 additional patients were included. Here, we report the results on four completed cohorts: patients with a BRCA1, BRCA2, CHEK2 or ATM mutation.Results: The overall objective response rate across different tumor types was 11% in the BRCA1-mutated (n = 27) and 21% in the BRCA2-mutated (n = 27) cohorts. Partial responses were seen in pancreatic cancer, gallbladder cancer, endocrine carcinoma of the pancreas and parathyroid cancer. One patient with a BRCA2 germline-mutated colon cancer has an ongoing complete response with 19+ months on treatment. Median progression-free survival in responding patients was 14+ months (5-34+ months). The clinical benefit rate was 63% in the BRCA1-mutated and 46% in the BRCA2-mutated cohorts. No clinical activity was observed in the ATM (n = 13) and CHEK2 (n = 14) cohorts.Conclusion: Olaparib showed efficacy in different cancer types harboring somatic or germline mutations in the BRCA1/2 genes but not in ATM and CHEK2. Patients with any cancer type harboring BRCA1/2 mutations should have access to olaparib.

Summary In 2018 the last active German hard coal mines have been abandoned and transitioned into the postmining phase. In the postmining phase, mine water pumping, necessary during active mining, becomes technically and economically unnecessary and unprofitable. As a consequence, the controlled process of mine water rebound to predefined levels increases the pore fluid pressure of subsurface rocks and changes the local stress field. As a result, faults may be (re-)activated inducing ground movements and microseismicity. This study presents an interdisciplinary approach consisting of geology, geomechanics, gas technology, geodesy, and geophysics in order to provide a process understanding how subsurface and surface are geomechanically coupled in the eastern Ruhr hard coal mining area, western Germany. Thus, mine workings and favourably oriented fractures represent the major pathways for mine water. This in accordance with CO2, 222Rn, and O2 anomalies detected along a fault. Rock matrices, however, are tight (mean porosity <1 %, mean permeability <1 mD). Furthermore, ground subsidence and microseismic events (–0.8 to 2.6 MLV) are spatially and temporally correlated with the mine water rebound and mine workings, but unrelated to tectonic faults. The applicability of these findings to other hard coal mining areas (e.g. Saarland, Ibbenbüren) will be tested.

Several targeted therapies are available through reimbursed organ-specific next-generation sequencing (NGS). Agnostic comprehensive genomic profiling (CGP) covering all classes of genomic alterations could improve access to molecularly-guided therapies (MGTs). PRECISION is an initiative launched by the Belgian Society of Medical Oncology (ESMO Open. 2022 Aug;7(4):100524). In the prospective GeNeo trial, CGP (FoundationOne CDx or Heme) was centrally done on tumor samples for patients with advanced solid tumors (NCT04641676). In parallel, organ-directed NGS panel testing was mandatory if reimbursed. Patients with no tissue sample were enrolled with a liquid biopsy. Results were discussed at a national molecular tumor board (MTB). Reasons for non-initiation of the recommended treatment were recorded. Clinical and genomic data are stored in the PRECISION database, with prospective follow-up up to 2 years. From October 2020 to April 2022, 1000 patients were enrolled at 13 sites. CGP results were available for 937 (843 tissue and 94 liquid biopsies) patients, out of which 918 were discussed at the MTB. The largest cohorts were breast (n=137), colorectal (n=128) and rare cancers (n=100). Turnaround-time from sample received to MTB recommendation was ≤ 28 days for 45% of cases and ≤ 37 days for 80%. 576 patients (63%) received at least one recommendation for CGP-based therapy. Cohorts with most treatment recommendations (>75% of cases) were bladder, biliary tract, skin and thyroid cancers. 72% of 469 patients who also had an organ-directed NGS test received at least one additional treatment recommendation based on CGP testing. Among the patients who received at least one MTB recommendation, 123 (21%) were treated accordingly. Reasons for non-compliance include patient ineligibility (26%), physician decision (23%) and treatment unavailability (22%). Follow-up continues. Tumor-agnostic CGP provides more treatment options to patients with advanced solid tumors when compared to organ-directed NGS panel testing. The national MTB provides recommendations within a clinically relevant timeframe and enhances the uptake of MGTs.

Treatment of advanced stage epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) is often complicated by the occurrence of acquired resistance, which emphasizes the need for improved treatment options. Based on a previously reported structure-activity relationship (SAR) study of Spautin-1, which resulted in the discovery of 10a, the search for more potent analogues was envisaged through optimization of the amine substituent. Our search led to the discovery of analogue 15b, harbouring the 2-[4-(4-fluoro-phenoxy)-phenyl]ethylamine substituent, among other potent and original analogues, with nanomolar activity towards EGFR-mutant NSCLC cells. Moreover, this compound 15b showed good selectivity for cancer cells over healthy lung epithelial cells and provides additive effects with food and drug administration (FDA) approved EGFR-tyrosine kinase inhibitors (TKIs), as proven by the co-administration of 15b with Afatinib. Altogether, we report promising lead compounds which show the potential to improve current treatment options.

BACKGROUND/AIM:Immunotherapy with PD-1/PDL1 blocking monoclonal antibodies has improved survival compared to the standard-of-care chemotherapy for several malignancies at different stages of these malignancies. Due to several reasons, many cancer patients in medical need have no access to these drugs. In this study, we aimed to investigate whether a low dose of nivolumab could also lead to a therapeutic response.PATIENTS AND METHODS:Patients with advanced cancer were treated with a flat low dose of 10 mg of nivolumab IV every two weeks at no drug cost.RESULTS:Disease control was noted in nine of the 18 patients. Two patients achieved complete remission, two had prolonged partial remission, and five had stable disease, of these only two experienced adverse events.CONCLUSION:A flat low dose of nivolumab may have clinical activity and is a cheap therapeutic option in patients in medical need for whom standard-dose immune checkpoint inhibitors are not accessible for any reason.

Background: Human epidermal growth factor receptor 2 (HER2) status is an important predictive biomarker in breast cancer (BC). Tumor heterogeneity has been described, with changes in HER2 expression levels between lesions and over the disease course. HER2 expression is assessed on tissue biopsies, at primary diagnosis and in metastatic lesions. A whole-body imaging technique such as PET/CT could help understand expression levels in different lesions. A 68Ga-labeled single domain antibody (sdAb) targeting the HER2 receptor has been developed and proven safe (Keyaerts et al., 2016). Imaging is performed at 90 min post-injection (pi). We report results of a phase II trial to assess the repeatability of the technique in 20 patients and the correlation of tracer uptake with HER2 tissue expression of the lesions present at the time of imaging. Methods: Twenty patients (pts) with a locally advanced or metastatic BC with at least one lesion of minimum 12 mm were included. Pts were injected intravenously with a typical protein mass of 100 µg and a radioactive dose ranging from 98-168 MBq 68GaNOTA-anti-HER2 sdAb. PET/CT images were obtained at 90 min pi. A second tracer injection followed by PET/CT was done with a maximal interval of 8 days. To assess repeatability, up to 5 lesions per pt were selected, with no more than 2 in a single organ. Peak Standard Uptake Values (SUVpeak) of the lesions were measured on both scans and compared with a t-test and Bland-Altman Plots. Images were compared to other available medical or imaging data and interpreted considering the subject’s disease course. Serum and plasma samples were collected before injection and between 60 and 365 days pi and stored for future detection of anti-drug antibodies (ADA) and liquid biopsies analysis for the presence of HER2 amplification. Tissue samples were assessed by central labs using mass spectrometry, immunohistochemistry and in fluorescence situ hybridization. Results: Twenty women with BC (6 HER2+, 14 HER2-) with a mean age of 58.6 y (37-81) were included. Three pts were scanned only once (2 due to withdrawal of consent, 1 due to covid pandemic). Repeatability of the technique was visually scored as excellent. For quantification, 50 lesions were compared on both scans in 17 pts without significant differences between the two measurements (p=0.40). The repeatability coefficient (RC) was 38.2%. The mean absolute percentage difference (MAPD) was 13.6%, comparable to repeat values reported for 18F-FDG. In 3 out of 6 HER2-positive (HER2+) patients, lesions showed high uptake, even better visible than using 18F-FDG in 2 of them. In 2 HER2+ subjects with a negative scan, lesions were confirmed to be true negatives: one patient did not relapse from BC but had tuberculosis; the other was confirmed to have a radiopneumonitis after radiotherapy and no relapse. In 1 HER2+ patient, the uptake was unexpectedly low. However, the HER2 status was also not reconfirmed in the metastatic setting for this subject. In 1 HER2-negative patient, the tumor HER2 status was changed from negative to positive based on a subsequent image-guided biopsy performed in this study. High tracer uptake was also seen in many of the patients presenting with HER2-low BC (IHC 1+ or 2+), indicating the potential of the tracer to detect low-level HER2 expression. Additional correlation to centrally performed tissue and blood analysis is ongoing. Conclusion: 68GaNOTA-Anti-HER2 PET/CT shows high uptake in HER2-expressing BC lesions but also in HER2-low lesions. The technique shows good repeatability and, in some cases, even better sensitivity than 18F-FDG PET/CT. Specificity was confirmed in relapse-free lesions such as tuberculosis and radiopneumonitis. Its sensitivity makes it a promising technique to assess HER2+ and HER2-low lesions in BC patients. Citation Format: Odrade Gondry, Catarina Xavier, Wim Waelput, Omar Al Dabssi, Marian Vanhoeij, Sandrine Aspeslagh, Sofie Joris, Christel Fontaine, Guy Verfaillie, Jacques De Grève, Katrien Glorieus, Ine Luyten, Frederik Vandenbroucke, Sophie Bourgeois, Laurens Raes, Sheeno Thyparambil, Nick Devoogdt, Ilse Vaneycken, Julie Cousaert, Vicky Caveliers, Hendrik Everaert, Tony Lahoutte, Marleen Keyaerts. Assessment of repeatability and uptake quantification of 68GaNOTA-anti-HER2 sdAb PET/CT in patients with locally advanced or metastatic breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-02-05.

Non-small cell lung cancer (NSCLC) patients harboring activating mutations in epidermal growth factor receptor (EGFR) are sensitive to therapy with EGFR tyrosine kinase inhibitors (TKI). Despite remarkable clinical responses using EGFR TKI, surviving drug tolerant cells serve as a reservoir from which drug resistant tumors may emerge. This study addresses the need for improved efficacy of EGFR TKI by identifying targets involved in functional drug tolerance against them. To this aim, a high-throughput siRNA kinome screen was performed using two EGFR TKI-sensitive EGFR-mutant NSCLC cell lines in the presence/absence of the second-generation EGFR TKI afatinib. From the screen, Serine/Threonine/Tyrosine Kinase 1 (STYK1) was identified as a target that when downregulated potentiates the effects of EGFR inhibition in vitro . We found that chemical inhibition of EGFR combined with the siRNA-mediated knockdown of STYK1 led to a significant decrease in cancer cell viability and anchorage-independent cell growth. Further, we show that STYK1 selectively interacts with mutant EGFR and that the interaction is disrupted upon EGFR inhibition. Finally, we identified fibroblast growth factor 1 (FGF1) as a downstream effector of STYK1 in NSCLC cells. Accordingly, downregulation of STYK1 counteracted the afatinib-induced upregulation of FGF1. Altogether, we unveil STYK1 as a valuable target to repress the pool of surviving drug tolerant cells arising upon EGFR inhibition. Co-targeting of EGFR and STYK1 could lead to a better overall outcome for NSCLC patients.