A phase 2 trial combining afatinib with cetuximab in patients with EGFR exon 20 insertion-positive non-small cell lung cancer

BACKGROUND

Epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutations are the third most common EGFR mutations in patients with non-small cell lung cancer (NSCLC) and are associated with primary resistance to EGFR tyrosine kinase inhibitors (TKIs). There is evidence of activity of combining EGFR TKIs with monoclonal antibodies. This study reports on the efficacy and safety of afatinib in combination with cetuximab.

METHODS

In this single-arm phase 2 trial, patients with advanced NSCLC harboring an EGFR ex20ins mutation were treated with afatinib 40 mg once daily in combination with cetuximab 500 mg/m2 every 2 weeks. The primary end point was disease control rate (DCR) at 18 weeks of treatment.

RESULTS

Thirty-seven patients started treatment, with a median age of 65 years (range, 40-80 years), 78% female, and 95% White. The study achieved its primary end point with a DCR of 54% at 18 weeks, an overall response rate (ORR) of 43%, and a 32% confirmed ORR. Best responses were partial (n = 16), stable (n = 16), progressive disease (n = 2), or not evaluable (n = 3). Median progression-free survival was 5.5 months (95% CI, 3.7-8.3 months) and median overall survival was 16.8 months (95% CI, 10.7-25.8 months). The most common treatment-related adverse events (TRAEs) were diarrhea (70%), rash (65%), dry skin (59%), paronychia (54%), and erythema (43%). Grade 3 TRAEs were reported in 54% of all patients.

CONCLUSIONS

Combination treatment with afatinib and cetuximab demonstrated antitumor activity with a DCR of 54% at 18 weeks and a 32% confirmed ORR. Toxicity was significant, although manageable, after dose reduction.

Optimized whole-genome sequencing workflow for tumor diagnostics in routine pathology practice

Two decades after the genomics revolution, oncology is rapidly transforming into a genome-driven discipline, yet routine cancer diagnostics is still mainly microscopy based, except for tumor type-specific predictive molecular tests. Pathology laboratories struggle to quickly validate and adopt biomarkers identified by genomics studies of new targeted therapies. Consequently, clinical implementation of newly approved biomarkers suffers substantial delays, leading to unequal patient access to these therapies. Whole-genome sequencing (WGS) can successfully address these challenges by providing a stable molecular diagnostic platform that allows detection of a multitude of genomic alterations in a single cost-efficient assay and facilitating rapid implementation, as well as by the development of new genomic biomarkers. Recently, the Whole-genome sequencing Implementation in standard Diagnostics for Every cancer patient (WIDE) study demonstrated that WGS is a feasible and clinically valid technique in routine clinical practice with a turnaround time of 11 workdays. As a result, WGS was successfully implemented at the Netherlands Cancer Institute as part of routine diagnostics in January 2021. The success of implementing WGS has relied on adhering to a comprehensive protocol including recording patient information, sample collection, shipment and storage logistics, sequencing data interpretation and reporting, integration into clinical decision-making and data usage. This protocol describes the use of fresh-frozen samples that are necessary for WGS but can be challenging to implement in pathology laboratories accustomed to using formalin-fixed paraffin-embedded samples. In addition, the protocol outlines key considerations to guide uptake of WGS in routine clinical care in hospitals worldwide.

Clinical Relevance of High Plasma Trough Levels of the Kinase Inhibitors Crizotinib, Alectinib, Osimertinib, Dabrafenib, and Trametinib in NSCLC Patients

BACKGROUND

the study aims to evaluate whether high plasma trough levels of the kinase inhibitors (K.I.s) crizotinib, alectinib, osimertinib, dabrafenib, and trametinib were associated with a higher risk of toxicity in non-small-cell lung cancer patients.

METHODS

In this retrospective cohort study, patients with non-small-cell lung cancer treated with the selected K.I.s were included if at least one plasma trough level at steady state (C min,ss ) was available. Data were extracted from electronic medical records and laboratory databases. The high group for each K.I. was defined as 10% of patients with the highest first C min,ss . The remaining patients were placed in the non-high group. The frequency of dose-limiting toxicities (DLTs), defined as adverse events leading to dose reduction, dose interruption, or permanent discontinuation, was compared between the 2 groups.

RESULTS

A total of 542 patients were included in the different K.I. groups. A high C min,ss of crizotinib (n = 96), alectinib (n = 105), osimertinib (n = 227), dabrafenib (n = 52), and trametinib (n = 62) correlated with a C min,ss ≥490, ≥870, ≥405, ≥150, and ≥25 ng/mL, respectively. DLTs were more common in the alectinib high group than in the alectinib non-high group (64% vs. 29%, P = 0.036). Liver toxicity was observed in 4 (36%) patients in the high group and 5 (5%) patients in the non-high group ( P = 0.007). For other K.I.s, no significant differences were observed in the frequency of DLTs between the high and non-high groups.

CONCLUSIONS

For alectinib, high C min,ss was correlated with a higher risk of DLT. No differences in the frequency of DLTs were observed between the high and non-high groups for crizotinib, osimertinib, dabrafenib, and trametinib.

Blood platelet RNA profiles do not enable for nivolumab response prediction at baseline in patients with non-small cell lung cancer

BACKGROUND

Anti-PD-(L)1 immunotherapy has emerged as a promising treatment approach for non-small cell lung cancer (NSCLC), though the response rates remain low. Pre-treatment response prediction may improve patient allocation for immunotherapy. Blood platelets act as active immune-like cells, thereby constraining T-cell activity, propagating cancer metastasis, and adjusting their spliced mRNA content.

OBJECTIVE

We investigated whether platelet RNA profiles before start of nivolumab anti-PD1 immunotherapy may predict treatment responses.

METHODS

We performed RNA-sequencing of platelet RNA samples isolated from stage III-IV NSCLC patients before treatment with nivolumab. Treatment response was scored by the RECIST-criteria. Data were analyzed using a predefined thromboSeq analysis including a particle-swarm-enhanced support vector machine (PSO/SVM) classification algorithm.

RESULTS

We collected and processed a 286-samples cohort, separated into a training/evaluation and validation series and subjected those to training of the PSO/SVM-classification algorithm. We observed only low classification accuracy in the 107-samples validation series (area under the curve (AUC) training series: 0.73 (95% -CI: 0.63-0.84, n = 88 samples), AUC evaluation series: 0.64 (95% -CI: 0.51-0.76, n = 91 samples), AUC validation series: 0.58 (95% -CI: 0.45-0.70, n = 107 samples)), employing a five-RNAs biomarker panel.

CONCLUSIONS

We concluded that platelet RNA may have minimally discriminative capacity for anti-PD1 nivolumab response prediction, with which the current methodology is insufficient for diagnostic application.

A qualitative study on the healthcare experiences of adolescents and young adults (AYA) with an uncertain or poor cancer prognosis

PURPOSE

Treatment advancements have improved life expectancy for adolescents and young adults (AYAs) with an uncertain and/or poor cancer prognosis (UPCP) and change clinical practice. This improved survival requires a different approach and specific expertise to meet the needs of this group. The aim of this study is to explore the health care experiences of AYAs with a UPCP.

METHODS

We conducted a multicenter qualitative study using semi-structured interviews and elements of the grounded theory by Corbin and Strauss.

RESULTS

Interviews were conducted with 46 AYAs with a UPCP. They were on average 33.4 years old (age range 23-44), and most of them were woman (63%). Additionally, five AYAs with a UPCP participated as AYA research partners in two focus groups. They were on average 31.8 years old and four of them were woman. AYAs with a UPCP reported four pillars for a satisfied healthcare experience: (1) trust, (2) tailored communication, (3) holistic empathic open attitude, and (4) care being offered (pro-)actively. They reported both optimal and suboptimal experiences about distrust based on a delay in diagnostic trajectory, lack of tailored communication and discussion of sensitive topics, preference for a holistic approach, and struggles with finding the way to get additional healthcare support.

CONCLUSION

For AYAs with a UPCP, it is important that both age-specific issues and issues related to the UPCP are understood and addressed; however, this seems not yet optimally implemented in clinical practice. This emphasizes the importance of providing this patient group with tailored care incorporating both aspects. Healthcare professionals need to be supported with training and tools to understand the healthcare needs of AYAs with a UPCP. AYAs can be empowered to take more control over their own healthcare needs.

A comprehensive overview of the heterogeneity of EGFR exon 20 variants in NSCLC and (pre)clinical activity to currently available treatments

Activating EGFR mutations are commonly observed in non-small cell lung cancer (NSCLC). About 4-10 % of all activating epidermal growth factor receptor (EGFR) mutations are heterogenous in-frame deletion and/or insertion mutations clustering within exon 20 (EGFRex20+). NSCLC patients with EGFRex20+ mutations are treated as a single disease entity, irrespective of the type and location of the mutation. Here, we provide a comprehensive assessment of the literature reporting both in vitro and clinical drug sensitivity across different EGFRex20+ mutations. The activating A763_Y764insFQEA mutation has a better tumor response in comparison with mutations in the near- and far regions directly following the C-helix and should therefore be treated differently. For other EGFRex20+ mutations marked differences in treatment responses have been reported indicating the need for a classification beyond the exon-based classification. A further classification can be achieved using a structure-function modeling approach and experimental data using patient-derived cell lines. The detailed overview of TKI responses for each EGFRex20+ mutation can assist treating physicians to select the most optimal drug for individual NSCLC patients.

Chemotherapy for patients with EGFR-mutated NSCLC after progression on EGFR-TKI's: Exploration of efficacy of unselected treatment in a multicenter cohort study

OBJECTIVES

In patients with Epidermal Growth Factor Receptor (EGFR)-mutated non-small cell lung (NSCLC) chemotherapy remains standard of care after progression on EGFR-tyrosine kinase inhibitors (TKIs). With the development of anti-angiogenic agents and immune checkpoint inhibitors the landscape of systemic regimens has changed significantly. This cohort study aims to evaluate the efficacy of chemotherapy regimens after progression on EGFR-TKI in a European population.

MATERIAL AND METHODS

All consecutive patients treated with chemotherapy after progression on EGFR-TKI for EGFR-mutated NSCLC, were identified in two tertiary centers in the Netherlands. Data on best response, progression free survival (PFS) and overall survival (OS) were extracted from medical records.

RESULTS

In total, 171 lines of chemotherapy were identified: platinum/pemetrexed (PP, n = 95), carboplatin/paclitaxel/bevacizumab/atezolizumab (CPBA, n = 32), paclitaxel/bevacizumab (PB, n = 36) and carboplatin/paclitaxel/bevacizumab (CPB, n = 8). Of the 171 lines, 106 were given as first-line after EGFR-TKI. Median PFS did not differ significantly between the first-line regimens (p = 0.50), with the highest PFS in PP (5.2 months [95% CI 4.5-5.9]) and CPBA (5.9 months [95% CI 3.8-80]). The majority of the PB group (n = 32) received this regimen in a second- or later line with a median PFS of 4.9 months (95% CI 3.3-6.6). First-line regimens had a median OS of 15.3 months (95% CI 11.6-18.9) with no significant difference between regimens (p = 0.85).

CONCLUSION

After progression on EGFR-TKI, patients with EGFR-mutated NSCLC show substantial benefit on different chemotherapy regimens. In particular, favorable outcomes were seen in patients treated with PP and CPBA as first-line chemotherapy, and PB in further lines of chemotherapy.

Early response evaluation of PD-1 blockade in NSCLC patients through FDG-PET-CT and T cell profiling of tumor-draining lymph nodes

Better biomarkers for programmed death - (ligand) 1 (PD-(L)1) checkpoint blockade in non-small cell lung cancer (NSCLC) are needed. We explored the predictive value of early response evaluation using Fluor-18-deoxyglucose positron emission tomography and pre- and on-treatment flowcytometric T-cell profiling in peripheral blood and tumor-draining lymph nodes (TDLN). The on-treatment evaluation was performed 7-14 days after the start of PD-1 blockade in NSCLC patients. These data were related to (pathological) tumor response, progression-free survival, and overall survival (OS). We found that increases in total lesion glycolysis (TLG) had a strong reverse correlation with OS (r = -0.93, p = 0.022). Additionally, responders showed decreased progressors and increased Treg frequencies on-treatment. Frequencies of detectable PD-1-expressing CD8⁺ T cells decreased in responders but remained stable in progressors. This was especially found in the TDLN. Changes in activated Treg rates in TDLN were strongly but, due to low numbers of data points, non-significantly correlated with ΔTLG and reversely correlated with OS.

Tobacco Smoking-Related Mutational Signatures in Classifying Smoking-Associated and Nonsmoking-Associated NSCLC

INTRODUCTION

Patient-reported smoking history is frequently used as a stratification factor in NSCLC-directed clinical research. Nevertheless, this classification does not fully reflect the mutational processes in a tumor. Next-generation sequencing can identify mutational signatures associated with tobacco smoking, such as single-base signature 4 and indel-based signature 3. This provides an opportunity to redefine the classification of smoking- and nonsmoking-associated NSCLC on the basis of individual genomic tumor characteristics and could contribute to reducing the lung cancer stigma.

METHODS

Whole genome sequencing data and clinical records were obtained from three prospective cohorts of metastatic NSCLC (N = 316). Relative contributions and absolute counts of single-base signature 4 and indel-based signature 3 were combined with relative contributions of age-related signatures to divide the cohort into smoking-associated ("smoking high") and nonsmoking-associated ("smoking low") clusters.

RESULTS

The smoking high (n = 169) and smoking low (n = 147) clusters differed considerably in tumor mutational burden, signature contribution, and mutational landscape. This signature-based classification overlapped considerably with smoking history. Yet, 26% of patients with an active smoking history were included in the smoking low cluster, of which 52% harbored an EGFR/ALK/RET/ROS1 alteration, and 4% of patients without smoking history were included in the smoking high cluster. These discordant samples had similar genomic contexts to the rest of their respective cluster.

CONCLUSIONS

A substantial subset of metastatic NSCLC is differently classified into smoking- and nonsmoking-associated tumors on the basis of smoking-related mutational signatures than on the basis of smoking history. This signature-based classification more accurately classifies patients on the basis of genome-wide context and should therefore be considered as a stratification factor in clinical research.

Detection and localization of early- and late-stage cancers using platelet RNA

Cancer patients benefit from early tumor detection since treatment outcomes are more favorable for less advanced cancers. Platelets are involved in cancer progression and are considered a promising biosource for cancer detection, as they alter their RNA content upon local and systemic cues. We show that tumor-educated platelet (TEP) RNA-based blood tests enable the detection of 18 cancer types. With 99% specificity in asymptomatic controls, thromboSeq correctly detected the presence of cancer in two-thirds of 1,096 blood samples from stage I-IV cancer patients and in half of 352 stage I-III tumors. Symptomatic controls, including inflammatory and cardiovascular diseases, and benign tumors had increased false-positive test results with an average specificity of 78%. Moreover, thromboSeq determined the tumor site of origin in five different tumor types correctly in over 80% of the cancer patients. These results highlight the potential properties of TEP-derived RNA panels to supplement current approaches for blood-based cancer screening.

Feasibility of whole genome sequencing based tumor diagnostics in routine pathology practice

The current increase in number and diversity of targeted anticancer agents poses challenges to the logistics and timeliness of molecular diagnostics (MolDx), resulting in underdiagnosis and treatment. Whole‐genome sequencing (WGS) may provide a sustainable solution for addressing current as well as future diagnostic challenges. The present study therefore aimed to prospectively assess feasibility, validity, and value of WGS in routine clinical practice. WGS was conducted independently of, and in parallel with, standard of care (SOC) diagnostics on routinely obtained tumor samples from 1,200 consecutive patients with metastatic cancer. Results from both tests were compared and discussed in a dedicated tumor board. From 1,200 patients, 1,302 samples were obtained, of which 1,216 contained tumor cells. WGS was successful in 70% (854/1,216) of samples with a median turnaround time of 11 days. Low tumor purity (<20%) was the main reason for not completing WGS. WGS identified 99.2% and SOC MolDx 99.7% of the total of 896 biomarkers found in genomic regions covered by both tests. Actionable biomarkers were found in 603/848 patients (71%). Of the 936 associated therapy options identified by WGS, 343 were identified with SOC MolDx (36.6%). Biomarker‐based therapy was started in 147 patients. WGS revealed 49 not previously identified pathogenic germline variants. Fresh‐frozen, instead of formalin‐fixed and paraffin‐embedded, sample logistics were easily adopted as experienced by the professionals involved. WGS for patients with metastatic cancer is well feasible in routine clinical practice, successfully yielding comprehensive genomic profiling for the vast majority of patients. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

High dose osimertinib in patients with advanced stage EGFR exon 20 mutation-positive NSCLC: Results from the phase 2 multicenter POSITION20 trial

INTRODUCTION

Patients with life-threatening advanced non-small cell lung cancer (NSCLC) who harbor an exon 20 deletion and/or insertion mutation (EGFRex20 + ) have limited effective treatment options. The high dose 3rd generation tyrosine kinase inhibitor (TKI) osimertinib shows promising in vitro activity in EGFRex20 + NSCLC tumors.

METHODS

The POSITION20 is a single arm phase II, multicenter study investigating 160 mg osimertinib in patients with EGFRex20+, T790M negative NSCLC. We allowed patients to be treatment naïve and to have asymptomatic brain metastases. The primary endpoint was overall response rate (ORR). Secondary outcomes were duration of response (DoR), progression free survival (PFS), overall survival (OS), and treatment related adverse events (trAEs).

RESULTS

From June 2018 to October 2021, 25 patients were enrolled across five centers in the Netherlands. The median age was 70 years (range, 47-87), 20 patients (80%) were women, and the median number of previous lines of therapy was 1 (range, 0-3). The exon 20 mutations were clustered between A763 and L777. The most common exon 20 mutations were p.(N771_H773dup) (n = 3) and p.(A767_V769dup) (n = 3). The ORR was 28% (95% CI, 12-49%), including seven partial responses, with a median DoR of 5.3 months (range, 2.7-27.6). The median PFS was 6.8 months (95% CI, 4.6-9.1) and the median OS was 15.2 months (95% CI, 14.3-16.0). The most common trAEs were diarrhea (72%), dry skin (44%), and fatigue (44%). The primary reason for discontinuation was progressive disease in 14 patients (56%).

CONCLUSION

The POSITION20 study showed modest antitumor activity in patients with EGFRex20 + NSCLC treated with 160 mg osimertinib, with a confirmed ORR of 28% and acceptable toxicity.

Abstract LB078: Tumor genomics in patients (pts) with advanced epidermal growth factor receptor mutant (EGFRm) non-small cell lung cancer (NSCLC) whose disease has progressed on first-line (1L) osimertinib therapy in the Phase II ORCHARD study

Background/Purpose: Osimertinib, a third-generation, irreversible, EGFR tyrosine kinase inhibitor (TKI), is the preferred 1L treatment for pts with EGFRm NSCLC. Unfortunately, most of these pts will eventually develop treatment resistance. ORCHARD is an ongoing Phase II platform study (NCT03944772) enrolling pts with EGFRm NSCLC, whose tumors progressed on 1L osimertinib, to a treatment group based on their tumor molecular profile. This exploratory analysis aimed to further understand the genomic landscape of resistance detected in tumor samples from pts with EGFRm NSCLC post-1L osimertinib, and to evaluate the concordance of resistance mechanisms identified in plasma and tissue.

Methods: Pts enrolled on ORCHARD (with advanced EGFRm NSCLC) provided tissue/plasma samples after progression on 1L osimertinib. Samples were analyzed for resistance mechanisms and testing concordance using next generation sequencing (NGS) either centrally (tissue [Foundation Medicine]; plasma [Guardant Health]) or locally. Alterations were determined based on reported results from respective assay.

Results: In total, 195 tissue samples (21 local and 174 central NGS) and 69 plasma samples (central NGS) were collected. The 174 central tissue samples were used for the genomic profiling: MET amplification occurred in 24% (42/174) of tumors; EGFR amplifications in 36% (62/174). Secondary EGFR mutations (C797X, L718X) and BRAF fusions were less common, 7% (13/174) and 5% (9/174), respectively, while other potentially actionable genomic alterations were rare: ERBB2 amplified/mutated (2%), ALK fusion (2%), RET fusions (1%), KRAS mutation (1%), BRAF V600E (1%).In the concordance analysis, 69 samples of matched tumor and plasma were used. Concordance was high between tissue and plasma for point mutations, particularly for sensitizing (64 samples; 89% concordance) and uncommon (G719X, L861X, S768I; 5 samples; 100% concordance) EGFR resistance mutations. The majority of EGFR (21/38 samples) and MET (16/30) amplifications were detected via tissue only. For BRAF, concordance was low: 4/5 BRAF fusions were found in tissue only, 1/5 in plasma only; 5/5 BRAF V600E mutations could be identified in plasma but only one of these was also identified in tissue.

Conclusions: Genomic profiling of pts with disease progression after 1L osimertinib showed that the most common identifiable resistance mutations were consistent with previous studies, however MET, EGFR amplifications and BRAF fusions were identified at higher rates than expected. Tissue and plasma provided different but potentially complementary results for detecting mechanisms of resistance, with differing levels of concordance across the mutations; further study is required in this area. Further exploration of 1L osimertinib resistance is continuing in the ongoing ORCHARD study.

Citation Format: Ryan J. Hartmaier, Aleksandra Markovets, Byoung Chul Cho, Adrianus J. de Langen, Sarah B. Goldberg, Jonathan Goldman, Xiuning Le, Isamu Okamoto, Jonathan W. Riess, Jan Cosaert, Helena Yu, Zofia Piotrowska. Tumor genomics in patients (pts) with advanced epidermal growth factor receptor mutant (EGFRm) non-small cell lung cancer (NSCLC) whose disease has progressed on first-line (1L) osimertinib therapy in the Phase II ORCHARD study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB078.

Relationship between Biodistribution and Tracer Kinetics of 11C-Erlotinib, 18F-Afatinib and 11C-Osimertinib and Image Quality Evaluation Using Pharmacokinetic/Pharmacodynamic Analysis in Advanced Stage Non-Small Cell Lung Cancer Patients

Background: Patients with non-small cell lung cancer (NSCLC) driven by activating epidermal growth factor receptor (EGFR) mutations are best treated with therapies targeting EGFR, i.e., tyrosine kinase inhibitors (TKI). Radiolabeled EGFR-TKI and PET have been investigated to study EGFR-TKI kinetics and its potential role as biomarker of response in NSCLC patients with EGFR mutations (EGFRm). In this study we aimed to compare the biodistribution and kinetics of three different EGFR-TKI, i.e., 11C-erlotinib, 18F-afatinib and 11C-osimertinib. Methods: Data of three prospective studies and 1 ongoing study were re-analysed; data from thirteen patients (EGFRm) were included for 11C-erlotinib, seven patients for 18F-afatinib (EGFRm and EGFR wild type) and four patients for 11C-osimertinib (EGFRm). From dynamic and static scans, SUV and tumor-to-blood (TBR) values were derived for tumor, lung, spleen, liver, vertebra and, if possible, brain tissue. AUC values were calculated using dynamic time-activity-curves. Parent fraction, plasma-to-blood ratio and SUV values were derived from arterial blood data. Tumor-to-lung contrast was calculated, as well as (background) noise to assess image quality. Results: 11C-osimertinib showed the highest SUV and TBR (AUC) values in nearly all tissues. Spleen uptake was notably high for 11C-osimertinib and to a lesser extent for 18F-afatinib. For EGFRm, 11C-erlotinib and 18F-afatinib demonstrated the highest tumor-to-lung contrast, compared to an inverse contrast observed for 11C-osimertinib. Tumor-to-lung contrast and spleen uptake of the three TKI ranked accordingly to the expected lysosomal sequestration. Conclusion: Comparison of biodistribution and tracer kinetics showed that 11C-erlotinib and 18F-afatinib demonstrated the highest tumor-to-background contrast in EGFRm positive tumors. Image quality, based on contrast and noise analysis, was superior for 11C-erlotinib and 18F-afatinib (EGFRm) scans compared to 11C-osimertinib and 18F-afatinib (EGFR wild type) scans.

Hypofractionated radiotherapy combined with targeted therapy or immunotherapy: Dutch survey on current practice, knowledge and challenges

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Radiotherapy referral during targeted therapy or immunotherapy occurs regularly.

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There is a knowledge gap regarding the implications of combined therapy.

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There is no consensus on expected toxicity of combined therapy.

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Multidisciplinary protocols regarding combined therapy are often not available.

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The application of radiotherapy treatment adaptations varies widely when combined with different systemic treatments.

Introduction

With the introduction of tyrosine kinase inhibitors and systemic antibodies, including immune checkpoint inhibitors, the survival of advanced-stage cancer patients has improved for many tumor types. These patients are increasingly referred for radiotherapy, but it is unclear whether radiotherapy combined with these drugs is safe. No international guidelines exist on whether or how to combine these drugs with radiotherapy. Therefore, we investigated the current clinical practice in the Netherlands regarding hypofractionated radiotherapy in patients using targeted drugs and immunotherapy.

Materials and methods

We sent a survey to all 21 Dutch radiotherapy institutes. Dedicated radiation oncologists, medical oncologists and pulmonologists were asked to fill out the survey. The questions explored their familiarity with the combination of targeted drugs and immunotherapy with radiotherapy, the encountered clinical difficulties and factors influencing treatment decisions.

Results

The survey was filled out by 54 respondents from 19 different institutes. The median annual number of patients per radiation oncologist referred for radiotherapy when using targeted drugs or immunotherapy was 10 and 15, respectively. Despite this high number, only 11% of the radiation oncologists stated that they had sufficient information (resources) for adequate treatment decision making. Among all physicians, 44% stated that there was insufficient knowledge within their institute regarding this topic. Only 17% stated that there was a multidisciplinary protocol available. The application of radiotherapy treatment adaptations (technique, dose, fractionation, field size) varied widely. Generally, there seemed to be no consensus regarding the expected toxicity of combined drug-radiotherapy treatments and the expected risk of tumor flare upon temporary drug discontinuation.

Conclusion

There is no consensus amongst involved medical specialties on expected toxicity. Consequently, it is necessary to perform clinical studies examining the safety of combined drug-radiotherapy treatments, to add radiotherapy to phase I-III clinical trials for new drugs and to incorporate outcomes into multidisciplinary, evidence-based guidelines.

Real-World Approach for Molecular Analysis of Acquired EGFR Tyrosine Kinase Inhibitor Resistance Mechanisms in NSCLC

INTRODUCTION

With the approval of first-line osimertinib treatment in stage IV EGFR-mutated NSCLC, detection of resistance mechanisms will become increasingly important-and complex. Clear guidelines for analyses of these resistance mechanisms are currently lacking. Here, we provide our recommendations for optimal molecular diagnostics in the post-EGFR tyrosine kinase inhibitor (TKI) resistance setting.

METHODS

We compared molecular workup strategies from three hospitals of 161 first- or second-generation EGFR TKI-treated cases and 159 osimertinib-treated cases. Laboratories used combinations of DNA next-generation sequencing (NGS), RNA NGS, in situ hybridization (ISH), and immunohistochemistry (IHC).

RESULTS

Resistance mechanisms were identified in 72 first-generation TKI cases (51%) and 85 osimertinib cases (57%). RNA NGS, when performed, revealed fusions or exon-skipping events in 4% of early TKI cases and 10% of osimertinib cases. Of the 30 MET and HER2 amplifications, 10 were exclusively detected by ISH or IHC, and not detected by DNA NGS, mostly owing to low tumor cell percentage (<30%) and possibly tumor heterogeneity.

CONCLUSIONS

Our real-world data support a method for molecular diagnostics, consisting of a parallel combination of DNA NGS, RNA NGS, MET ISH, and either HER2 ISH or IHC. Combining RNA and DNA isolation into one step limits dropout rates. In case of financial or tissue limitations, a sequential approach is justifiable, in which RNA NGS is only performed in case no resistance mechanisms are identified. Yet, this is suboptimal as-although rare-multiple acquired resistance mechanisms may occur.

Abstract P230: A phase 1/2 study of BLU-945, a highly potent and selective inhibitor of epidermal growth factor receptor (EGFR) resistance mutations, in patients with EGFR-mutant non-small cell lung cancer (NSCLC)

BACKGROUND Activating EGFR mutations such as exon 19 deletion (ex19del) and L858R mutations, exon 19 insertions (ex19ins), and point mutations L861Q, G719X, and S768I are oncogenic drivers in lung adenocarcinoma, the most common NSCLC subtype. Although EGFR-targeted therapies, including first-, second-, and third-generation tyrosine kinase inhibitors (TKIs), have improved outcomes in patients (pts) with EGFR-mutant (EGFRm) NSCLC, resistance to these drugs is inevitable. BLU-945 is an investigational fourth-generation EGFR TKI designed to suppress both activating and on-target resistance EGFR mutations, such as C797S and T790M. Preclinical data showed BLU-945 has nanomolar potency against EGFRm/T790M double and EGFRm/T790M/C797S triple mutants with &gt;450-fold selectivity for these mutants over wild-type EGFR in biochemical and cellular assays, and demonstrated robust preclinical antitumor activity, including in intracranial tumors harboring these mutations, providing the therapeutic rationale for BLU-945 clinical development. METHODS BLU-945-1101 (NCT04862780) is an international, open-label, first-in-human, phase 1/2 study designed to evaluate safety, tolerability, and antitumor activity of BLU-945 in pts with EGFRm NSCLC. Key eligibility criteria include adults with pathologically confirmed metastatic NSCLC with an activating EGFR mutation per local assessment (including ex19del or L858R); Eastern Cooperative Oncology Group performance status 0–2; and previous treatment with ≥1 EGFR-targeted TKI. Pts with asymptomatic brain metastases and on stable doses of corticosteroids are eligible. Key exclusion criteria are any additional known primary driver alterations, including but not limited to pathologic aberrations of EGFR exon 20 (insertions), KRAS, BRAF V600E, NTRK1/2/3, HER2, ALK, ROS1, MET, or RET. Phase 1 primary endpoints are maximum tolerated dose, recommended phase 2 dose (RP2D), and safety. The phase 2 primary endpoint is overall response rate (ORR) by RECIST 1.1. Phase 1 secondary endpoints include ORR, duration of response (DOR), pharmacokinetics (PK), and pharmacodynamics (PD); phase 2 secondary endpoints include DOR, disease control rate (DCR), clinical benefit rate (CBR), progression free survival (PFS), overall survival (OS), time to intracranial progression and intracranial response rate, PK, PD, and safety. Phase 1 dose escalation (N≈60) will be conducted using Bayesian optimal interval design. In the phase 2 dose expansion (N≈61), pts will be enrolled into 3 groups based on mutation profile and treated at the RP2D: primary group 1 for pts with EGFR T790M and C797S (n≈37); exploratory group 2 for pts with EGFR T790M but not C797S (n≈12); exploratory group 3 for pts with EGFR C797S but not T790M (n≈12). Group 1 will use Simon’s 2-stage design to test the null hypothesis of ORR ≤20% against a 1-sided alternative of ≥40%. Pts may receive treatment until disease progression or unacceptable toxicity. Recruitment has started and approximately 30 sites will be open for enrollment across North America, Europe, and Asia.

Citation Format: David Spigel, Koichi Goto, D. Ross Camidge, Yasir Elamin, Adrianus J. de Langen, Natasha B. Leighl, Anna Minchom, Zofia Piotrowska, David Planchard, Karen Reckamp, Faris Albayya, Jennifer Green, Sean Kim, Melinda Louie-Gao, Renata Sawtell, Alena Zalutskaya, Byoung Chul Co. A phase 1/2 study of BLU-945, a highly potent and selective inhibitor of epidermal growth factor receptor (EGFR) resistance mutations, in patients with EGFR-mutant non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P230.

Limited evolution of the actionable metastatic cancer genome under therapeutic pressure

Genomic profiling is critical for the identification of treatment options for patients with metastatic cancer, but it remains unclear how frequently this procedure should be repeated during the course of the disease. To address this, we analyzed whole-genome sequencing (WGS) data of 250 biopsy pairs, longitudinally collected over the treatment course of 231 adult patients with a representative variety of metastatic solid malignancies. Within the biopsy interval (median, 6.4 months), patients received one or multiple lines of (mostly) standard-of-care (SOC) treatments, with all major treatment modalities being broadly represented. SOC biomarkers and biomarkers for clinical trial enrollment could be identified in 23% and 72% of biopsies, respectively. For SOC genomic biomarkers, we observed full concordance between the first and the second biopsy in 99% of pairs. Of the 219 biomarkers for clinical trial enrollment that were identified in the first biopsies, we recovered 94% in the follow-up biopsies. Furthermore, a second WGS analysis did not identify additional biomarkers for clinical trial enrollment in 91% of patients. More-frequent genomic evolution was observed when considering specific genes targeted by small-molecule inhibitors or hormonal therapies (21% and 22% of cases, respectively). Together, our data demonstrate that there is limited evolution of the actionable genome of treated metastases. A single WGS analysis of a metastatic biopsy is generally sufficient to identify SOC genomic biomarkers and to identify investigational treatment opportunities.

PD-L1 PET/CT imaging with radiolabeled durvalumab in patients with advanced stage non-small cell lung cancer

Background: Better biomarkers are needed to predict treatment outcome in NSCLC patients treated with anti PD-(L)1 checkpoint inhibitors. PD-L1 immunohistochemistry has limited predictive value, possibly due to tumor heterogeneity of PD-L1 expression. Noninvasive PD-L1 imaging using ⁸⁹Zr-durvalumab might provide a better reflection of tumor PD-L1 expression and can therefore support treatment decision making. Patients and Methods: NSCLC patients eligible for second line immunotherapy treatment were enrolled. Patients received two injections of ⁸⁹Zr-durvalumab; one without a preceding dose of unlabeled durvalumab ('tracer dose only') and one with a preceding dose of 750 mg durvalumab, directly prior to tracer injection. Up to four PET/CT scans were obtained after tracer injection. Post-imaging acquisition, patients were treated with 750mg durvalumab every two weeks. Tracer biodistribution and tumor uptake were visually assessed and quantified as standardized uptake value (SUV) and both imaging acquisitions were compared. Tumor tracer uptake was correlated with PD-L1 expression and clinical outcome, defined as treatment response to durvalumab treatment. Results: Thirteen patients were included and ten completed all scheduled PET scans. No tracer related adverse events were observed and all patients started durvalumab treatment. Biodistribution analysis showed ⁸⁹Zr-durvalumab accumulation in the blood pool, liver and spleen. Serial imaging showed that image acquisition 120 hours post injection delivered the best tumor to blood pool ratio. Most tumor lesions were visualized with the tracer-dose only versus the co-injection imaging acquisition (25% vs 13.5% of all lesions). Uptake heterogeneity was observed within (range SUVpeak 0.2 to 15.1) and between patients. Tumor uptake was higher in patients with treatment response or stable disease, compared to patients with disease progression according to RECIST 1.1. However, this difference was not statistically significant (median SUVpeak 4.9 vs 2.4, P = 0.06). SUVpeak correlated better with the combined tumor and immune cell PD-L1 score than with PD-L1 expression on tumor cells, although both were not statistically significant (P = 0.06 and P = 0.93, respectively). Conclusion: ⁸⁹Zr-durvalumab was safe without any tracer related adverse events and more tumor lesions were visualized using the tracer dose only imaging acquisition. ⁸⁹Zr-durvalumab tumor uptake was higher in patients with response to durvalumab treatment, but did not correlate with tumor PD-L1 IHC.

Multicenter Comparison of Molecular Tumor Boards in The Netherlands: Definition, Composition, Methods, and Targeted Therapy Recommendations

BACKGROUND

Molecular tumor boards (MTBs) provide rational, genomics-driven, patient-tailored treatment recommendations. Worldwide, MTBs differ in terms of scope, composition, methods, and recommendations. This study aimed to assess differences in methods and agreement in treatment recommendations among MTBs from tertiary cancer referral centers in The Netherlands.

MATERIALS AND METHODS

MTBs from all tertiary cancer referral centers in The Netherlands were invited to participate. A survey assessing scope, value, logistics, composition, decision-making method, reporting, and registration of the MTBs was completed through on-site interviews with members from each MTB. Targeted therapy recommendations were compared using 10 anonymized cases. Participating MTBs were asked to provide a treatment recommendation in accordance with their own methods. Agreement was based on which molecular alteration(s) was considered actionable with the next line of targeted therapy.

RESULTS

Interviews with 24 members of eight MTBs revealed that all participating MTBs focused on rare or complex mutational cancer profiles, operated independently of cancer type-specific multidisciplinary teams, and consisted of at least (thoracic and/or medical) oncologists, pathologists, and clinical scientists in molecular pathology. Differences were the types of cancer discussed and the methods used to achieve a recommendation. Nevertheless, agreement among MTB recommendations, based on identified actionable molecular alteration(s), was high for the 10 evaluated cases (86%).

CONCLUSION

MTBs associated with tertiary cancer referral centers in The Netherlands are similar in setup and reach a high agreement in recommendations for rare or complex mutational cancer profiles. We propose a "Dutch MTB model" for an optimal, collaborative, and nationally aligned MTB workflow.

IMPLICATIONS FOR PRACTICE

Interpretation of genomic analyses for optimal choice of target therapy for patients with cancer is becoming increasingly complex. A molecular tumor board (MTB) supports oncologists in rationalizing therapy options. However, there is no consensus on the most optimal setup for an MTB, which can affect the quality of recommendations. This study reveals that the eight MTBs associated with tertiary cancer referral centers in The Netherlands are similar in setup and reach a high agreement in recommendations for rare or complex mutational profiles. The Dutch MTB model is based on a collaborative and nationally aligned workflow with interinstitutional collaboration and data sharing.

First-in-human study of 89Zr-pembrolizumab PET/CT in patients with advanced stage non-small-cell lung cancer

Background: Tumor programmed-death ligand-1 (PD-L1) proportion score is the current method to select non-small-cell lung cancer (NSCLC) patients for single agent treatment with pembrolizumab, a programmed cell death-1 (PD-1) monoclonal antibody. However, not all patients respond to therapy. Better understanding of in vivo drug behavior may help to select patients that benefit most. Methods: NSCLC patients eligible for pembrolizumab monotherapy as first or later line therapy were enrolled. Patients received two injections of ⁸⁹Zr-pembrolizumab; one without a preceding dose of pembrolizumab and one with 200 mg pembrolizumab, directly prior to tracer injection. Up to four PET/CT scans were obtained after tracer injection. Post-imaging acquisition, patients were treated with 200 mg pembrolizumab, every three weeks. Tumor uptake and tracer biodistribution were visually assessed and quantified as standardized uptake value (SUV). Tumor tracer uptake was correlated with PD-1 and PD-L1 expression and response to pembrolizumab treatment. Results: Twelve NSCLC patients were included. One patient experienced grade 3 myalgia after tracer injection. ⁸⁹Zr-pembrolizumab was observed in the blood pool, liver and spleen. Tracer uptake was visualized in 47,2% of 72 tumor lesions measuring ≥20 mm long axis diameter, and substantial uptake heterogeneity was observed within and between patients. Uptake was higher in patients with response to pembrolizumab treatment (n = 3) compared to patients without a response (n = 9), although this was not statistically significant (median SUVpeak 11.4 vs 5.7, P = 0.066). No significant correlations were found with PD-L1 or PD-1 immunohistochemistry. Conclusion: ⁸⁹Zr-pembrolizumab injection was safe with only one grade 3 adverse event, possibly immune related, out of 12 patients. ⁸⁹Zr-pembrolizumab tumor uptake was higher in patients with response to pembrolizumab treatment, but did not correlate with PD-L1 or PD-1 immunohistochemistry.

Stage I non-small cell lung cancer: Treatment modalities, Dutch daily practice and future perspectives

OBJECTIVES

Several treatment modalities are available for patients with stage I non-small cell lung cancer (NSCLC). Over the past decade, these treatment modalities have been further investigated and might have changed current treatment regimens. In this review we present an overview of the treatment options, developments and future perspectives for stage I NSCLC. Furthermore, we describe the current use of these treatment modalities in the Netherlands.

MATERIALS AND METHODS

A bibliographical search was performed in PubMed and the Cochrane Library for publications concerning treatment modalities for stage I NSCLC. In addition, evidence-based guidelines of the European Society for Medical Oncology (ESMO) and the National Comprehensive Cancer Network (NCCN) were studied.

RESULTS

The guideline-recommended treatment for operable stage I NSCLC patients is a lobectomy with systematic lymph node dissection. Inoperable patients or those refusing surgery are offered stereotactic ablative radiotherapy (SABR). Percutaneous ablation, such as radiofrequency ablation, is a non-surgical minimally invasive technique offered to those who are ineligible for surgery or SABR. The role of systemic therapy is currently limited. However, the efficacy of immunotherapy is being investigated in clinical trials. In the Netherlands, an increasing use of SABR and a relative decrease in resection rates have been observed.

CONCLUSION

Surgery and SABR are currently the prevailing treatment modalities for stage I NSCLC patients. Despite optimization of treatment regimens, survival of patients with stage I NSCLC remains to be improved. Future studies are required to optimize treatment strategies, but also to investigate factors influencing treatment decision-making for patients with stage I NSCLC.

Phase I and Pharmacologic Study of Olaparib in Combination with High-dose Radiotherapy with and without Concurrent Cisplatin for Non-Small Cell Lung Cancer

PURPOSE

To identify an MTD of olaparib, a PARP inhibitor, in combination with loco-regional radiotherapy with/without cisplatin for the treatment of non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

Olaparib dose was escalated in two groups: radiotherapy (66 Gy/24 fractions in 2.75 Gy/fraction) with and without daily cisplatin (6 mg/m²), using time-to-event continual reassessment method with a 1-year dose-limiting toxicity (DLT) period. The highest dose level with a DLT probability <15% was defined as MTD. Poly ADP-ribose (PAR) inhibition and radiation-induced PAR-ribosylation (PARylation) were determined in peripheral blood mononuclear cells.

RESULTS

Twenty-eight patients with loco-regional or oligometastatic disease (39%) were treated: 11 at olaparib 25 mg twice daily and 17 at 25 mg once daily. The lowest dose level with cisplatin was above the MTD due to hematologic and late esophageal DLT. The MTD without cisplatin was olaparib 25 mg once daily. At a latency of 1-2.8 years, severe pulmonary adverse events (AE) were observed in 5 patients across all dose levels, resulting in 18% grade 5 pulmonary AEs. Exploratory analyses indicate an association with the radiation dose to the lungs. At the MTD, olaparib reduced PAR levels by more than 95% and abolished radiation-induced PARylation. Median follow-up of survivors was 4.1 years. Two-year loco-regional control was 84%, median overall survival in patients with locally advanced NSCLC was 28 months.

CONCLUSIONS

Combined mildly hypofractionated radiotherapy and low-dose daily cisplatin and olaparib was not tolerable due to esophageal and hematologic toxicity. Severe pulmonary toxicity was observed as well, even without cisplatin. More conformal radiotherapy schedules with improved pulmonary and esophageal sparing should be explored.

Quantification of PD-L1 Expression with 18F-BMS-986192 PET/CT in Patients with Advanced-Stage Non-Small Cell Lung Cancer

The aim of this work was to quantify the uptake of ¹⁸F-BMS-986192, a programmed cell death ligand 1 (PD-L1) adnectin PET tracer, in patients with non-small cell lung cancer. To this end, plasma input kinetic modeling of dynamic tumor uptake data with online arterial blood sampling was performed. In addition, the accuracy of simplified uptake metrics such as SUV was investigated. Methods: Data from a study with ¹⁸F-BMS-986192 in patients with advanced-stage non-small cell lung cancer eligible for nivolumab treatment were used if a dynamic scan was available and lesions were present in the field of view of the dynamic scan. After injection of ¹⁸F-BMS-986192, a 60-min dynamic PET/CT scan was started, followed by a 30-min whole-body PET/CT scan. Continuous arterial and discrete arterial and venous blood sampling were performed to determine a plasma input function. Tumor time-activity curves were fitted by several plasma input kinetic models. Simplified uptake parameters included tumor-to-blood ratio as well as several SUV measures. Results: Twenty-two tumors in 9 patients were analyzed. The arterial plasma input single-tissue reversible compartment model with fitted blood volume fraction seems to be the most preferred model as it best fitted 11 of 18 tumor time-activity curves. The distribution volume (V _T ) ranged from 0.4 to 4.8 mL⋅cm^-3 Similar values were obtained with an image-derived input function. From the simplified measures, SUV normalized for body weight at 50 and 67 min after injection correlated best with V _T , with an R ² of more than 0.9. Conclusion: A single-tissue reversible model can be used to quantify tumor uptake of the PD-L1 PET tracer ¹⁸F-BMS-986192. SUV at 60 min after injection, normalized for body weight, is an accurate simplified parameter for uptake assessment of baseline studies. To assess its predictive value for response evaluation during programmed cell death protein 1 or PD-L1 immune checkpoint inhibition, further validation of SUV against V _T based on an image-derived input function is recommended.

Effect of Pembrolizumab After Stereotactic Body Radiotherapy vs Pembrolizumab Alone on Tumor Response in Patients With Advanced Non-Small Cell Lung Cancer: Results of the PEMBRO-RT Phase 2 Randomized Clinical Trial

Importance

Many patients with advanced non-small cell lung cancer (NSCLC) receiving immunotherapy show primary resistance. High-dose radiotherapy can lead to increased tumor antigen release, improved antigen presentation, and T-cell infiltration. This radiotherapy may enhance the effects of checkpoint inhibition.

Objective

To assess whether stereotactic body radiotherapy on a single tumor site preceding pembrolizumab treatment enhances tumor response in patients with metastatic NSCLC.

Design, Setting, and Participants

Multicenter, randomized phase 2 study (PEMBRO-RT) of 92 patients with advanced NSCLC enrolled between July 1, 2015, and March 31, 2018, regardless of programmed death-ligand 1 (PD-L1) status. Data analysis was of the intention-to-treat population.

Interventions

Pembrolizumab (200 mg/kg every 3 weeks) either alone (control arm) or after radiotherapy (3 doses of 8 Gy) (experimental arm) to a single tumor site until confirmed radiographic progression, unacceptable toxic effects, investigator decision, patient withdrawal of consent, or a maximum of 24 months.

Main Outcomes and Measures

Improvement in overall response rate (ORR) at 12 weeks from 20% in the control arm to 50% in the experimental arm with P < .10.

Results

Of the 92 patients enrolled, 76 were randomized to the control arm (n = 40) or the experimental arm (n = 36). Of those, the median age was 62 years (range, 35-78 years), and 44 (58%) were men. The ORR at 12 weeks was 18% in the control arm vs 36% in the experimental arm (P = .07). Median progression-free survival was 1.9 months (95% CI, 1.7-6.9 months) vs 6.6 months (95% CI, 4.0-14.6 months) (hazard ratio, 0.71; 95% CI, 0.42-1.18; P = .19), and median overall survival was 7.6 months (95% CI, 6.0-13.9 months) vs 15.9 months (95% CI, 7.1 months to not reached) (hazard ratio, 0.66; 95% CI, 0.37-1.18; P = .16). Subgroup analyses showed the largest benefit from the addition of radiotherapy in patients with PD-L1-negative tumors. No increase in treatment-related toxic effects was observed in the experimental arm.

Conclusions and Relevance

Stereotactic body radiotherapy prior to pembrolizumab was well tolerated. Although a doubling of ORR was observed, the results did not meet the study's prespecified end point criteria for meaningful clinical benefit. Positive results were largely influenced by the PD-L1-negative subgroup, which had significantly improved progression-free survival and overall survival. These results suggest that a larger trial is necessary to determine whether radiotherapy may activate noninflamed NSCLC toward a more inflamed tumor microenvironment.

Trial Registration

ClinicalTrials.gov identifier: NCT02492568.

Genomic Profiling Identifies Outcome-Relevant Mechanisms of Innate and Acquired Resistance to Third-Generation Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Therapy in Lung Cancer

PURPOSE

Third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are effective in acquired resistance (AR) to early-generation EGFR TKIs in EGFR-mutant lung cancer. However, efficacy is marked by interindividual heterogeneity. We present the molecular profiles of pretreatment and post-treatment samples from patients treated with third-generation EGFR TKIs and their impact on treatment outcomes.

METHODS

Using the databases of two lung cancer networks and two lung cancer centers, we molecularly characterized 124 patients with EGFR p.T790M-positive AR to early-generation EGFR TKIs. In 56 patients, correlative analyses of third-generation EGFR TKI treatment outcomes and molecular characteristics were feasible. In addition, matched post-treatment biopsy samples were collected for 29 patients with progression to third-generation EGFR TKIs.

RESULTS

Co-occurring genetic aberrations were found in 74.4% of EGFR p.T790-positive samples (n = 124). Mutations in TP53 were the most frequent aberrations detected (44.5%; n = 53) and had no significant impact on third-generation EGFR TKI treatment. Mesenchymal-epithelial transition factor (MET) amplifications were found in 5% of samples (n = 6) and reduced efficacy of third-generation EGFR TKIs significantly (eg, median progression-free survival, 1.0 months; 95% CI, 0.37 to 1.72 v 8.2 months; 95% CI, 1.69 to 14.77 months; P ≤ .001). Genetic changes in the 29 samples with AR to third-generation EGFR TKIs were found in EGFR (eg, p.T790M loss, acquisition of p.C797S or p.G724S) or in other genes (eg, MET amplification, KRAS mutations).

CONCLUSION

Additional genetic aberrations are frequent in EGFR-mutant lung cancer and may mediate innate and AR to third-generation EGFR TKIs. MET amplification was strongly associated with primary treatment failure and was a common mechanism of AR to third-generation EGFR TKIs. Thus, combining EGFR inhibitors with TKIs targeting common mechanisms of resistance may delay AR.

Repeatability of [18F]FDG PET/CT total metabolic active tumour volume and total tumour burden in NSCLC patients

Background

Total metabolic active tumour volume (TMATV) and total tumour burden (TTB) are increasingly studied as prognostic and predictive factors in non-small cell lung cancer (NSCLC) patients. In this study, we investigated the repeatability of TMATV and TTB as function of uptake interval, positron emission tomography/computed tomography (PET/CT) image reconstruction settings, and lesion delineation method. We used six lesion delineation methods, four direct PET image-derived delineations and two based on a majority vote approach, i.e. intersection between two or more delineations (MV2) and between three or more delineations (MV3). To evaluate the accuracy of those methods, they were compared with a reference delineation obtained from the consensus of the segmentations performed by three experienced observers. Ten NSCLC patients underwent two baseline whole-body [¹⁸F]2-Fluoro-2-deoxy-2-D-glucose ([¹⁸F]FDG) PET/CT studies on separate days, within 3 days. Two scans were obtained on each day at 60 and 90 min post-injection to assess the influence of tracer uptake interval. PET/CT images were reconstructed following the European Association of Nuclear Medicine Research Ltd. (EARL) compliant settings and with point-spread-function (PSF) modelling. Repeatability between the measurements of each day was determined and the influence of uptake interval, reconstruction settings, and lesion delineation method was assessed using the generalized estimating equations model.

Results

Based on the Jaccard index with the reference delineation, the MV2 lesion delineation method was the most successful method for automated lesion segmentation. The best overall repeatability (lowest repeatability coefficient, RC) was found for TTB from 90 min of tracer uptake scans reconstructed with EARL compliant settings and delineated with 41% of lesion’s maximum SUV method (RC = 11%). In most cases, TMATV and TTB repeatability were not significantly affected by changes in tracer uptake time or reconstruction settings. However, some lesion delineation methods had significantly different repeatability when applied to the same images.

Conclusions

This study suggests that under some circumstances TMATV and TTB repeatability are significantly affected by the lesion delineation method used. Performing the delineation with a majority vote approach improves reliability and does not hamper repeatability, regardless of acquisition and reconstruction settings. It is therefore concluded that by using a majority vote based tumour segmentation approach, TMATV and TTB in NSCLC patients can be measured with high reliability and precision.

Electronic supplementary material

The online version of this article (10.1186/s13550-019-0481-1) contains supplementary material, which is available to authorized users.

Afatinib and Cetuximab in Four Patients With EGFR Exon 20 Insertion-Positive Advanced NSCLC

INTRODUCTION

EGFR exon 20 insertions comprise 4% to 9% of EGFR mutated NSCLC. Despite being an oncogenic driver, they are associated with primary resistance to EGFR tyrosine kinase inhibitors (TKIs). We hypothesized that dual EGFR blockade with afatinib, an irreversible EGFR TKI, and cetuximab, a monoclonal antibody against EGFR, could induce tumor responses.

METHODS

Four patients with EGFR exon 20 insertion-positive NSCLC were treated with afatinib 40 mg once daily and cetuximab 250 mg/m² to 500 mg/m² every 2 weeks.

RESULTS

All patients had stage IV adenocarcinoma of the lung harboring an EGFR exon 20 insertion mutation. Previous lines of treatment consisted of platinum doublet chemotherapy (n = 4) and EGFR TKI (n = 2). Three of four patients showed a partial response according to Response Evaluation Criteria in Solid Tumors (RECIST 1.1). Median progression-free survival was 5.4 months (95% confidence interval: 0.0 - 14.2 months; range 2.7 months - 17.6 months). Toxicity was manageable with appropriate skin management and dose reduction being required in two patients.

CONCLUSIONS

Dual EGFR blockade with afatinib and cetuximab may induce tumor responses in patients with EGFR exon 20 insertion-positive NSCLC.

Non-invasive tumor genotyping using radiogenomic biomarkers, a systematic review and oncology-wide pathway analysis

With targeted treatments playing an increasing role in oncology, the need arises for fast non-invasive genotyping in clinical practice. Radiogenomics is a rapidly evolving field of research aimed at identifying imaging biomarkers useful for non-invasive genotyping. Radiogenomic genotyping has the advantage that it can capture tumor heterogeneity, can be performed repeatedly for treatment monitoring, and can be performed in malignancies for which biopsy is not available. In this systematic review of 187 included articles, we compiled a database of radiogenomic associations and unraveled networks of imaging groups and gene pathways oncology-wide. Results indicated that ill-defined tumor margins and tumor heterogeneity can potentially be used as imaging biomarkers for 1p/19q codeletion in glioma, relevant for prognosis and disease profiling. In non-small cell lung cancer, FDG-PET uptake and CT-ground-glass-opacity features were associated with treatment-informing traits including EGFR-mutations and ALK-rearrangements. Oncology-wide gene pathway analysis revealed an association between contrast enhancement (imaging) and the targetable VEGF-signalling pathway. Although the need of independent validation remains a concern, radiogenomic biomarkers showed potential for prognosis prediction and targeted treatment selection. Quantitative imaging enhanced the potential of multiparametric radiogenomic models. A wealth of data has been compiled for guiding future research towards robust non-invasive genomic profiling.

Structural Alterations of MET Trigger Response to MET Kinase Inhibition in Lung Adenocarcinoma Patients

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PD-L1 IHC in NSCLC with a global and methodological perspective

In summary, the PD-L1 biomarker discussed here highlights the importance of understanding the practice of IHC. This can be used to the patients advantage, with appropriate usage. The currently available literature on PD-L1 IHC from a methodologic point of view has not shown that different assays are comparable. The route of laboratory developed test and commercial test validation is the same: challenging and complex. Executing this process along proper methodologic lines is needed to ensure that patients receive the most accurate and representative test outcomes.

Anaplastic lymphoma kinase inhibition in metastatic non-small cell lung cancer: clinical impact of alectinib

A subset of non-small cell lung cancer (NSCLC) tumors (5%) harbors an anaplastic lymphoma kinase (ALK) translocation that drives tumorigenesis. The clinically approved first-line treatment crizotinib specifically inhibits ALK and improves progression-free survival (PFS) in treated and untreated patients by 4 months compared to standard chemotherapy. While some patients relapse after crizotinib treatment due to resistance mutations in ALK, second-generation ALK inhibitors effectively induce tumor response and prolong PFS. Alectinib, a second-generation ALK inhibitor, has recently been approved for ALK-rearranged NSCLC after patients progressed on crizotinib. Alectinib is able to inhibit several crizotinib- and ceritinib-resistant ALK mutations in vitro. Furthermore, alectinib is a more potent tyrosine kinase inhibitor (TKI), with favorable safety profile, and has increased penetration into the central nervous system, inhibiting crizotinib-resistant brain metastases. The discovery of effective personalized therapies to combat ALK-rearranged NSCLC such as alectinib is an example of the importance of genomic profiling of NSCLC and provides an excellent template for future discoveries in managing these tumors.

Swarm Intelligence-Enhanced Detection of Non-Small-Cell Lung Cancer Using Tumor-Educated Platelets

Blood-based liquid biopsies, including tumor-educated blood platelets (TEPs), have emerged as promising biomarker sources for non-invasive detection of cancer. Here we demonstrate that particle-swarm optimization (PSO)-enhanced algorithms enable efficient selection of RNA biomarker panels from platelet RNA-sequencing libraries (n = 779). This resulted in accurate TEP-based detection of early- and late-stage non-small-cell lung cancer (n = 518 late-stage validation cohort, accuracy, 88%; AUC, 0.94; 95% CI, 0.92-0.96; p < 0.001; n = 106 early-stage validation cohort, accuracy, 81%; AUC, 0.89; 95% CI, 0.83-0.95; p < 0.001), independent of age of the individuals, smoking habits, whole-blood storage time, and various inflammatory conditions. PSO enabled selection of gene panels to diagnose cancer from TEPs, suggesting that swarm intelligence may also benefit the optimization of diagnostics readout of other liquid biopsy biosources.

Abstract LB-248: RNA-sequencing of tumor-educated platelets enables nivolumab immunotherapy response prediction

I: Studies have shown the activity of anti-PD(L)-1 therapies in patients with advanced non-small-cell lung cancer (NSCLC), however response rates are rather low (~20%). Therefore, there is an urgent need to identify biomarkers that predict patient outcome to immunotherapy (IT). Previously we have shown that RNA signatures of tumor-educated platelets (TEPs) may have predictive value for tumor type-specific diagnostics. Platelets are intimately involved in immune responses. We hypothesized that TEP RNA profiles have predictive value for IT response. M: We collected baseline platelet pellets, isolated from whole blood by differential centrifugation, from 389 stage IV NSCLC patients treated with Nivolumab (table 1). Tumor response was evaluated at 3 and 6 months and reported according to RECIST 1.1. Platelet pellets were subjected to total RNA isolation, SMARTer cDNA amplification, and libraries were sequenced on the HiSeq platform. Raw data (~20 M reads per sample) was mapped to the human genome, intron-spanning spliced RNA reads were selected for analysis. Gene panels were calculated by ANOVA statistics. R: Until now 64 samples were sequenced, 30 of patients with clinical benefit (PR or SD at six months; CB) and 34 of patients with no clinical benefit (PD; no CB). 40 randomly selected samples (20 CB, 20 no CB) were used for training of the support vector machine (SVM)-based therapy response classification algorithm. 24 samples were used for independent evaluation of the classifier. Hierarchical clustering of genes with p&lt;0.05 among these groups identified significant separation between CB and no CB (p&lt;0.001, Fisher’s exact test). The SVM nivolumab response prediction algorithm, predicted the remaining 24 samples with an accuracy of more than 85%, as opposed to at random classification (p&lt;0.01). D: TEP RNA profiles potentially enable liquid biopsy-based response prediction to IT. Large-scale validation is ongoing and up to date results of the NSCLC cohort will be presented.

Table 1.Patient CharacteristicsTotal CohortNumber of patients389Start of treatmentAugust 2015-november 2016Date lock1th of November, 2016Gender (Male)56%Age (med, range)64.5 years (29-83)Treatment lines1st line1%2nd line72%&gt;2nd line27%DiagnosisNon-Squamous68%Squamous26%Other6%ResponseClinical benefit27%Progressive54%Unknown19%PD-L1 expressionResults expected in april

Citation Format: Mirte Muller, Myron Best, Nik Sol, Anna-Larissa N. Niemeijer, Adrienne Vancura, Robert D. Schouten, Jeroen J.N. Hiltermann, Sjors G.J.G. In 't Veld, Daan van den Broek, Vincent van der Noort, Adrianus J. de Langen, Ed M.D. Schuuring, Thomas Wurdinger, Michel M. van den Heuvel. RNA-sequencing of tumor-educated platelets enables nivolumab immunotherapy response prediction [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-248. doi:10.1158/1538-7445.AM2017-LB-248

Nonsmall cell lung carcinoma: diagnostic difficulties in small biopsies and cytological specimens

The pathological and molecular classification of lung cancer has become substantially more complex over the past decade. For diagnostic purposes on small samples, additional stains are frequently required to distinguish between squamous cell carcinoma and adenocarcinoma. Subsequently, for advanced nonsquamous cell nonsmall cell lung carcinoma (NSCLC) patients, predictive analyses on epidermal growth factor receptor, anaplastic lymphoma kinase and ROS1 are required. In NSCLCs negative for these biomarkers, programmed death ligand-1 immunohistochemistry is performed. Small samples (biopsy and cytology) require “tissue” management, which is best achieved by the interaction of all physicians involved.

High PD-1 expression on regulatory and effector T-cells in lung cancer draining lymph nodes

The treatment of advanced nonsmall cell lung cancer (NSCLC) with PD-1/PD-L1 immune checkpoint inhibitors has improved clinical outcome for a proportion of patients. The current challenge is to find better biomarkers than PD-L1 immunohistochemistry (IHC) that will identify patients likely to benefit from this therapy. In this exploratory study we assessed the differences in T-cell subsets and PD-1 expression levels on T-cells in tumour-draining lymph nodes (TDLNs) and peripheral blood mononuclear cells (PBMCs). To evaluate this, flow cytometric analyses were performed on endobronchial ultrasound-guided (EBUS) fine-needle aspirates (FNA) from TDLNs of patients with NSCLC, and the results were compared to paired PBMC samples. For a select number of patients, we were also able to obtain cells from a non-TDLN (NTDLN) sample. Our data show that the frequency of PD-1⁺ CD4⁺ and CD8⁺ T-cells, as well as the PD-1 expression level on activated regulatory T (aT_reg) and CD4⁺ and CD8⁺ T-cells, are higher in TDLNs than in PBMCs and, in a small sub-analysis, NTDLNs. These elevated PD-1 expression levels in TDLNs may reflect tumour-specific T-cell priming and conditioning, and may serve as a predictive or early-response biomarker during PD-1 checkpoint blockade.

Therapeutic approach to treating patients with BRAF-mutant lung cancer: latest evidence and clinical implications

Lung adenocarcinoma is known for its high rate of somatic mutations and genomic rearrangements. The identification of epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements that sensitize tumors to specific drugs has changed the therapeutic approach and prognosis in these molecularly-defined subgroups. Several other key genetic alterations have been identified, of which BRAF mutations are found in 4% of non-small cell lung cancer (NSCLC) cases. Targeted drugs against BRAF and downstream MEK were recently approved for the treatment of BRAF-positive melanoma and have entered clinical evaluation in NSCLC. In this review we discuss the latest evidence on the treatment of BRAF-mutated NSCLC, including tumor biology, targeted treatment with BRAF and MEK inhibitors, therapeutic resistance and strategies to overcome resistance.

Outcomes of Hypofractionated High-Dose Radiotherapy in Poor-Risk Patients with "Ultracentral" Non-Small Cell Lung Cancer

INTRODUCTION

We defined "ultracentral" lung tumors as centrally located non-small cell lung cancers with planning target volumes overlapping the trachea or main bronchi. Increased toxicity has been reported after both conventional and stereotactic radiotherapy for such lesions. We studied outcomes after 12 fractions of 5 Gy (BED10 = 90 Gy, heterogeneous dose distribution) to ultracentral tumors in patients unfit for surgery or conventional chemoradiotherapy.

METHODS

Clinical outcomes and dosimetric details were analyzed in 47 consecutive patients with single primary or recurrent ultracentral non-small cell lung cancer treated between 2010 and 2015. Those irradiated previously or with metastasis to sites other than the brain and adrenal glands were excluded. Treatments were delivered using volumetric modulated arc therapy.

RESULTS

The median age was 77.5 years, 49% of patients had a World Health Organization performance score of 2 or higher, and the median planning target volume was 104.5cm(3) (range 17.7-508.5). At a median follow-up of 29.3 months, median overall survival was 15.9 months, and 3-year survival was 20.1%. No isolated local recurrences were observed. Grade 3 or higher toxicity was recorded in 38% of patients, with 21% scored as having a "possible" (n = 2) or "likely" (n = 8) treatment-related death between 5.2 and 18.2 months after treatment. Fatal pulmonary hemorrhage was observed in 15% of patients.

CONCLUSIONS

Unfit patients with ultracentral tumors who were treated using this scheme had a high local control and a median survival of 15.9 months. Despite manifestation of rates of a fatal lung bleeding comparable to those seen with conventional radiotherapy for endobronchial tumors, the overall rate of G5 toxicity is of potential concern. Additional work is needed to identify tumor and treatment factors related to hemorrhage.

Repeatability of 18F-FDG uptake measurements in tumors: a metaanalysis

PET with the glucose analog (18)F-FDG is increasingly used to monitor tumor response to therapy. To use quantitative measurements of tumor (18)F-FDG uptake for assessment of tumor response, the repeatability of this quantitative metabolic imaging method needs to be established. Therefore, we determined the repeatability of different standardized uptake value (SUV) measurements using the available data.

METHODS

A systematic literature search was performed to identify studies addressing (18)F-FDG repeatability in malignant tumors. The level of agreement between test and retest values of 2 PET uptake measures, maximum SUV (SUV(max)) and mean SUV (SUV(mean)), was assessed with the coefficient of repeatability using generalized linear mixed-effects models. In addition, the influence of tumor volume on repeatability was assessed. Principal component transformation was used to compare the reproducibility of the 2 different uptake measures.

RESULTS

Five cohorts were identified for this metaanalysis. For SUV(max) and SUV(mean), datasets of 86 and 102 patients, respectively, were available. Percentage repeatability is a function of the level of uptake. SUV(mean) had the best repeatability characteristics; for serial PET scans, a threshold of a combination of 20% as well as 1.2 SUV(mean) units was most appropriate. After adjusting for uptake rate, tumor volume had minimal influence on repeatability.

CONCLUSION

SUV(mean) had better repeatability performance than SUV(max). Both measures showed poor repeatability for lesions with low (18)F-FDG uptake. We recommend the evaluation of biologic effects in PET by reporting a combination of minimal relative and absolute changes to account for test-retest variability.

Effects of image characteristics on performance of tumor delineation methods: a test-retest assessment

PET can be used to monitor response during chemotherapy and assess biologic target volumes for radiotherapy. Previous simulation studies have shown that the performance of various automatic or semiautomatic tumor delineation methods depends on image characteristics. The purpose of this study was to assess test-retest variability of tumor delineation methods, with emphasis on the effects of several image characteristics (e.g., resolution and contrast).

METHODS

Baseline test-retest data from 19 non-small cell lung cancer patients were obtained using (18)F-FDG (n = 10) and 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) (n = 9). Images were reconstructed with varying spatial resolution and contrast. Six different types of tumor delineation methods, based on various thresholds or on a gradient, were applied to all datasets. Test-retest variability of metabolic volume and standardized uptake value (SUV) was determined.

RESULTS

For both tracers, size of metabolic volume and test-retest variability of both metabolic volume and SUV were affected by the image characteristics and tumor delineation method used. The median volume test-retest variability ranged from 8.3% to 23% and from 7.4% to 29% for (18)F-FDG and (18)F-FLT, respectively. For all image characteristics studied, larger differences (≤10-fold higher) were seen in test-retest variability of metabolic volume than in SUV.

CONCLUSION

Test-retest variability of both metabolic volume and SUV varied with tumor delineation method, radiotracer, and image characteristics. The results indicate that a careful optimization of imaging and delineation method parameters is needed when metabolic volume is used, for example, as a response assessment parameter.

Monitoring response to antiangiogenic therapy in non-small cell lung cancer using imaging markers derived from PET and dynamic contrast-enhanced MRI

With antiangiogenic agents, tumor shrinkage may be absent, despite survival benefit. The present study assessed the predictive value of molecular imaging for the identification of survival benefit during antiangiogenic treatment with bevacizumab and erlotinib in patients with advanced non-small cell lung cancer.

METHODS

Patients were evaluated using an imaging protocol including CT, 18F-FDG PET, H2(15)O PET, and dynamic contrast-enhanced MRI to derive measurements on tumor size, glucose metabolism, perfusion, and microvascular permeability. The percentage change in imaging parameters after 3 wk of treatment as compared with baseline was calculated and correlated with progression-free survival (PFS).

RESULTS

Forty-four patients were included, and 40 underwent CT and 18F-FDG PET at both time points. Complete datasets, containing all imaging modalities, were available for 14 patients. Bevacizumab and erlotinib treatment resulted in decreased metabolism, perfusion, and tumor size. A decrease in standardized uptake value or tumor perfusion of more than 20% at week 3 was associated with longer PFS (9.7 vs. 2.8 mo, P=0.01, and 12.5 vs. 2.9 mo, P=0.009, respectively). Whole-tumor Ktrans (the endothelial transfer constant) was not associated with PFS, but patients with an increase of more than 15% in the SD of tumor Ktrans values-that is, an increase in regions with low or high Ktrans values-after 3 wk had shorter PFS (2.3 vs. 7.0 mo, P=0.008). A partial response, according to the response evaluation criteria in solid tumors (RECIST), at week 3 was also associated with prolonged PFS (4.6 vs. 2.9 mo, P=0.017). However, 40% of patients with a partial response as their best RECIST response still had stable disease at week 3. In these cases tumor perfusion was already decreased and Ktrans heterogeneity showed no increase, indicating that the latter parameters seem to be more discriminative than RECIST at the 3-wk time point.

CONCLUSION

PET and dynamic contrast-enhanced MRI were able to identify patients who benefit from bevacizumab and erlotinib treatment. Molecular imaging seems to allow earlier response evaluation than CT.

Repeatability of metabolically active volume measurements with 18F-FDG and 18F-FLT PET in non-small cell lung cancer

In addition to tumor size measurements with CT, there is a need for quantitative measurements of metabolic active volumes, possibly adding to tracer uptake measurements in oncologic response evaluation with PET. The aim of this study was to evaluate the metabolic volume test-retest variability in (18)F-FDG and 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) PET studies for various commonly used volumes of interest (VOIs) and the dependence of that variability on lesion size and relative radiotracer uptake.

METHODS

Twenty non-small cell lung cancer patients were scanned twice with (18)F-FDG (n = 11) or (18)F-FLT (n = 9). VOIs were defined on images reconstructed with normalization- and attenuation-weighted ordered-subset expectation maximization using 4 isocontours (A41%, A50%, and A70% thresholds, adapted for local background, and 50% threshold, uncorrected for background). Statistical analysis comprised intraclass correlation coefficients and Bland-Altman analysis.

RESULTS

In the (18)F-FDG and (18)F-FLT groups, 34 and 20 lesions, respectively, were analyzed. Median volumes at the A50% threshold were 3.31 and 2.19 mL (interquartile range, 1.91-8.90 and 1.52-7.27 mL) for (18)F-FDG and (18)F-FLT, respectively. Intraclass correlation coefficients were greater than 0.9, with the exception of the A70%-based metabolic volumes for (18)F-FLT. For lesions greater than 4.2 mL, repeatability coefficients (RCs = 1.96 × SD) of the percentage difference ranged from 22% to 37% for (18)F-FDG and from 39% to 73% for (18)F-FLT, depending on the VOI method being used. Repeatability was better for larger tumors, but there was no dependence on absolute uptake (standardized uptake value).

CONCLUSION

Results indicate that changes of greater than 37% for (18)F-FDG and greater than 73% for (18)F-FLT (1.96 × SD) for lesions with A50% metabolic volumes greater than 4.2 mL represent a biologic effect. For smaller lesions (A50% VOI < 4.2 mL), an absolute change of 1.0 and 0.9 mL for (18)F-FDG and (18)F-FLT, respectively, is biologically relevant. Considering the balance between the success rate of automatic tumor delineation and repeatability of metabolic volume, a 50% threshold with correction for local background activity (A50%) seems optimal among the VOI methods evaluated.

Use of H2(15)O-PET and DCE-MRI to measure tumor blood flow

Positron emission tomography (PET) with H2(15)O and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) provide noninvasive measurements of tumor blood flow. Both tools offer the ability to monitor the direct target of antiangiogenic treatment, and their use is increasingly being studied in trials evaluating such drugs. Antiangiogenic therapy offers great potential and, to an increasing extent, benefit for oncological patients in a variety of palliative and curative settings. Because this type of targeted therapy frequently results in consolidation of the tumor mass instead of regression, monitoring treatment response with the standard volumetric approach (Response Evaluation Criteria in Solid Tumors) leads to underestimation of the response rate. Monitoring direct targets of anticancer therapy might be superior to indirect size changes. In addition, measures of tumor blood flow contribute to a better understanding of tumor biology. This review shows that DCE-MRI and H2(15)O-PET provide reliable measures of tumor perfusion, provided that a certain level of standardization is applied. Heterogeneity in scan acquisition and data analysis complicates the interpretation of study results. Also, limitations inherent to both techniques must be considered when interpreting DCE-MRI and H2(15)O-PET results. This review focuses on the technical and physiological aspects of both techniques and aims to provide the essential information necessary to critically evaluate the use of DCE-MRI and H2(15)O-PET in an oncological setting.