Treatment Monitoring of Immunotherapy and Targeted Therapy Using 18F-FET PET in Patients with Melanoma and Lung Cancer Brain Metastases: Initial Experiences.

We investigated the value of O-(2-18F-fluoroethyl)-l-tyrosine (18F-FET) PET for treatment monitoring of immune checkpoint inhibition (ICI) or targeted therapy (TT) alone or in combination with radiotherapy in patients with brain metastasis (BM) since contrast-enhanced MRI often remains inconclusive. Methods: We retrospectively identified 40 patients with 107 BMs secondary to melanoma (n = 29 with 75 BMs) or non-small cell lung cancer (n = 11 with 32 BMs) treated with ICI or TT who had 18F-FET PET (n = 60 scans) for treatment monitoring from 2015 to 2019. Most patients (n = 37; 92.5%) had radiotherapy during the course of the disease. In 27 patients, 18F-FET PET was used to differentiate treatment-related changes from BM relapse after ICI or TT. In 13 patients, 18F-FET PET was performed for response assessment to ICI or TT using baseline and follow-up scans (median time between scans, 4.2 mo). In all lesions, static and dynamic 18F-FET PET parameters were obtained (i.e., mean tumor-to-brain ratios [TBR], time-to-peak values). Diagnostic accuracies of PET parameters were evaluated by receiver-operating-characteristic analyses using the clinical follow-up or neuropathologic findings as a reference. Results: A TBR threshold of 1.95 differentiated BM relapse from treatment-related changes with an accuracy of 85% (P = 0.003). Metabolic responders to ICI or TT on 18F-FET PET had a significantly longer stable follow-up (threshold of TBR reduction relative to baseline, ≥10%; accuracy, 82%; P = 0.004). Furthermore, at follow-up, time to peak in metabolic responders increased significantly (P = 0.019). Conclusion:18F-FET PET may add valuable information for treatment monitoring in BM patients treated with ICI or TT.

Genetic Heterogeneity of MET-Aberrant NSCLC and Its Impact on the Outcome of Immunotherapy.

INTRODUCTION: Robust data on the outcome of MET-aberrant NSCLC with nontargeted therapies are limited, especially in consideration of the heterogeneity of MET-amplified tumors (METamp). METHODS: A total of 337 tumor specimens of patients with MET-altered Union for International Cancer Control stage IIIB/IV NSCLC were analyzed using next-generation sequencing, fluorescence in situ hybridization, and immunohistochemistry. The evaluation focused on the type of MET aberration, co-occurring mutations, programmed death-ligand 1 expression, and overall survival (OS). RESULTS: METamp tumors (n = 278) had a high frequency of co-occurring mutations (>80% for all amplification levels), whereas 57.6% of the 59 patients with MET gene and exon 14 (METex14) tumors had no additional mutations. In the METamp tumors, with increasing gene copy number (GCN), the frequency of inactivating TP53 mutations increased (GCN < 4: 58.2%; GCN ≥ 10: 76.5%), whereas the frequency of KRAS mutations decreased (GCN < 4: 43.2%; GCN ≥ 10: 11.8%). A total of 10.1% of all the METamp tumors with a GCN ≥ 10 had a significant worse OS (4.0 mo; 95% CI: 1.9-6.0) compared with the tumors with GCN < 10 (12.0 mo; 95% confidence interval [CI]: 9.4-14.6). In the METamp NSCLC, OS with immune checkpoint inhibitor (ICI) therapy was significantly better compared with chemotherapy with 19.0 months (95% CI: 15.8-22.2) versus 8.0 months (95% CI: 5.8-10.2, p < 0.0001). No significant difference in median OS was found between ICI therapy and chemotherapy in the patients with METex14 (p = 0.147). CONCLUSIONS: METex14, METamp GCN ≥ 10, and METamp GCN < 10 represent the subgroups of MET-dysregulated NSCLC with distinct molecular and clinical features. The patients with METex14 do not seem to benefit from immunotherapy in contrast to the patients with METamp, which is of particular relevance for the prognostically poor METamp GCN ≥ 10 subgroup.

Co-occurrence of targetable mutations in Non-small cell lung cancer (NSCLC) patients harboring MAP2K1 mutations.

BACKGROUND: MAP2K1 mutations are rare in non-small cell lung cancer (NSCLC) and considered to be mutually exclusive from known driver mutations. Activation of the MEK1-cascade is considered pivotal in resistance to targeted therapy approaches, and MAP2K1 K57 N mutation could be linked to resistance in preclinical models. We set out this study to detect MAP2K1 mutations and potentially targetable co-mutations using a molecular multiplex approach. METHODS: Between 2012 and 2018, we routinely analyzed 14.512 NSCLC patients with two next-generation sequencing (NGS) panels. In a subset of patients, fluorescence in-situ hybridization was performed to detect rearrangements or amplifications. We assessed clinical parameters and co-occurring mutations and compared treatment outcomes of different forms of systemic therapy. RESULTS: We identified 66 (0.5%) patients with MAP2K1 mutations. Both adenocarcinoma (n = 62) and squamous cell carcinoma (n = 4) histology. The presence of the mutations was linked to smoking, and transversions were more common than transitions. K57 N was the most frequent MAP2K1 mutation (n = 25). Additional mutations were found in 57 patients (86.4%). Mutations of TP53 were detected in 33 patients, followed by KEAP1 mutations in 28.1%. 24 patients (36.4%) had either MAP2K1-only or a co-occurring aberration considered targetable, including EGFR mutations, a BRAF V600E mutation and ROS1 rearrangements. Outcome analyses revealed a trend toward benefit from pemetrexed treatment. CONCLUSION: Our analysis shows that MAP2K1-mutated NSCLC patients might frequently present with potentially targetable aberrations. Their role in providing resistance in these subtypes and the possible therapeutic opportunities justify further analyses of this rare NSCLC subgroup.

Sorafenib and everolimus in patients with advanced solid tumors and KRAS-mutated NSCLC: A phase I trial with early pharmacodynamic FDG-PET assessment.

BACKGROUND: Treatment of patients with solid tumors and KRAS mutations remains disappointing. One option is the combined inhibition of pathways involved in RAF-MEK-ERK and PI3K-AKT-mTOR. METHODS: Patients with relapsed solid tumors were treated with escalating doses of everolimus (E) 2.5-10.0 mg/d in a 14-day run-in phase followed by combination therapy with sorafenib (S) 800 mg/d from day 15. KRAS mutational status was assessed retrospectively in the escalation phase. Extension phase included KRAS-mutated non-small-cell lung cancer (NSCLC) only. Pharmacokinetic analyses were accompanied by pharmacodynamics assessment of E by FDG-PET. Efficacy was assessed by CT scans every 6 weeks of combination. RESULTS: Of 31 evaluable patients, 15 had KRAS mutation, 4 patients were negative for KRAS mutation, and the KRAS status remained unknown in 12 patients. Dose-limiting toxicity (DLT) was not reached. The maximum tolerated dose (MTD) was defined as 7.5 mg/d E + 800 mg/d S due to toxicities at previous dose level (10 mg/d E + 800 mg/d S) including leucopenia/thrombopenia III° and pneumonia III° occurring after the DLT interval. The metabolic response rate in FDG-PET was 17% on day 5 and 20% on day 14. No patient reached partial response in CT scan. Median progression free survival (PFS) and overall survival (OS) were 3.25 and 5.85 months, respectively. CONCLUSIONS: Treatment of patients with relapsed solid tumors with 7.5 mg/d E and 800 mg/d S is safe and feasible. Early metabolic response in FDG-PET was not confirmed in CT scan several weeks later. The combination of S and E is obviously not sufficient to induce durable responses in patients with KRAS-mutant solid tumors.

Acquired KRAS mutation and loss of low-level MET amplification after durable response to crizotinib in a patient with lung adenocarcinoma.

OBJECTIVES: Resistance to tyrosine kinase inhibitor (TKI) therapy occurs inevitably in lung cancer patients with targetable genetic alterations. MET amplification has found to be an oncogenic driver in lung cancer with several reports showing response to MET TKI especially in cases with high-level amplification. MATERIALS AND METHODS: We report the case of a patient with lung adenocarcinoma harbouring low-level MET amplification and strong MET expression who was treated with crizotinib. RESULTS: The patient developed a durable response to crizotinib. A KRAS mutation and loss of MET amplification was found in a new lesion at time of progression as a potential mechanism of acquired resistance. CONCLUSION: MET amplification is a continuous biomarker with responses to MET TKI observed even in patients with low-level amplification. KRAS mutations may act as a resistance mechanism to MET inhibition in MET dependent lung cancer.

Safety and Efficacy of Crizotinib in Patients With Advanced or Metastatic ROS1-Rearranged Lung Cancer (EUCROSS): A European Phase II Clinical Trial.

INTRODUCTION: ROS1 rearrangements are found in 1% of lung cancer patients. Therapeutic efficacy of crizotinib in this subset has been shown in early phase trials in the United States and East Asia. Here we present data on efficacy and safety of a prospective phase II trial evaluating crizotinib in European ROS1-positive patients (EUCROSS). PATIENTS AND METHODS: The trial was a multicenter, single-arm phase II trial (Clinicaltrial.gov identifier: NCT02183870). Key eligibility criteria included patients who were 18 years of age or older with advanced/metastatic lung cancer and centrally confirmed ROS1-rearranged lung cancer (fluorescence-in situ hybridization). Treatment included 250 mg crizotinib twice daily. The primary endpoint was investigator-assessed objective response rate (ORR) (Response Evaluation Criteria in Solid Tumors, version 1.1). Key secondary endpoints were progression-free survival (PFS), overall survival, efficacy by independent radiologic review, safety, health-related quality of life, and molecular characterization of tumor tissue. RESULTS: Thirty-four patients received treatment. Four patients were excluded from efficacy analysis. Investigator ORR was 70% (95% confidence interval [CI]: 51-85; 21 of 30 patients) and median PFS was 20.0 months (95% CI: 10.1-not reached). Two patients with ROS1 wild-type sequences assessed by DNA sequencing had progression as best response. CD74-ROS1-positive patients had a trend towards a higher ORR and longer median PFS. TP53-co-mutant patients had a significantly shorter median PFS than wild-type patients (7.0 months, 95% CI: 1.7-20.0 versus 24.1 months, 95% CI: 10.1-not reached; p = 0.022). Treatment-related adverse events were documented in 33 of 34 patients (97%). CONCLUSIONS: Crizotinib is highly effective and safe in patients with ROS1-rearranged lung cancer. ROS1-/TP53-co-aberrant patients had a significantly worse outcome compared to TP53 wild-type patients.

K-ras Mutation Subtypes in NSCLC and Associated Co-occuring Mutations in Other Oncogenic Pathways.

INTRODUCTION: Although KRAS mutations in NSCLC have been considered mutually exclusive driver mutations for a long time, there is now growing evidence that KRAS-mutated NSCLC represents a genetically heterogeneous subgroup. We sought to determine genetic heterogeneity with respect to cancer-related co-mutations and their correlation with different KRAS mutation subtypes. METHODS: Diagnostic samples from 4507 patients with NSCLC were analyzed by next-generation sequencing by using a panel of 14 genes and, in a subset of patients, fluorescence in situ hybridization. Next-generation sequencing with an extended panel of 14 additional genes was performed in 101 patients. Molecular data were correlated with clinical data. Whole-exome sequencing was performed in two patients. RESULTS: We identified 1078 patients with KRAS mutations, of whom 53.5% had at least one additional mutation. Different KRAS mutation subtypes showed different patterns of co-occurring mutations. Besides mutations in tumor protein p53 gene (TP53) (39.4%), serine/threonine kinase 11 gene (STK11) (19.8%), kelch like ECH associated protein 1 gene (KEAP1) (12.9%), and ATM serine/threonine kinase gene (ATM) (11.9%), as well as MNNG HOS Transforming gene (MET) amplifications (15.4%) and erb-b2 receptor tyrosine kinase 2 gene (ERBB2) amplifications (13.8%, exclusively in G12C), we found rare co-occurrence of targetable mutations in EGFR (1.2%) and BRAF (1.2%). Whole-exome sequencing of two patients with co-occurring phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha gene (PIK3CA) mutation revealed clonality of mutated KRAS in one patient and subclonality in the second, suggesting different evolutionary backgrounds. CONCLUSION: KRAS-mutated NSCLC represents a genetically heterogeneous subgroup with a high frequency of co-occurring mutations in cancer-associated pathways, partly associated with distinct KRAS mutation subtypes. This diversity might have implications for understanding the variability of treatment outcome in KRAS-mutated NSCLC and for future trial design.