EGFR mutation testing and treatment decisions in patients progressing on first- or second-generation epidermal growth factor receptor tyrosine kinase inhibitors.

BACKGROUND: The objective of this study was to investigate real-world EGFR mutation testing in patients with metastatic non-small cell lung cancer (NSCLC) upon progression on first-/second-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKI), and subsequent treatments received. METHODS: Flatiron Health electronic health records-derived database was used to identify adult patients with metastatic NSCLC treated with first-/second-generation EGFR-TKI from 11/2015-09/2017, with start of first EGFR-TKI defined as the index date. Patients were stratified by receipt of EGFR-TKI as first-line (1 L) or later-line (2 L+) treatment. Mutation testing and subsequent therapies following first-/second-generation EGFR-TKI were described. RESULTS: Overall, 782 patients (1 L = 435; 2 L+ =347) were included. Median age was 69.0 years, 63.6% were female, 56.3% were white, 87.1% were treated in community-based practices, and 30.1% of patients died during the study period; median follow-up was 309.0 days. Among the 294 (1 L = 160; 2L+ =134) patients who received subsequent therapies, treatments included chemotherapy only (1 L = 15.6%; 2L+ =21.6%), immunotherapy only (1 L = 13.8%; 2 L+ =41.0%), and targeted therapies (1 L = 70.0%; 2 L+ =36.6%). Specifically, 40 (25.0%) 1 L patients and 7 (5.2%) 2 L+ patients received osimertinib as subsequent therapy. Before the start of subsequent therapy, EGFR T790M resistance mutation testing was performed in 88 (29.9%) patients (1 L = 63 [39.4%]; 2 L+ =25 [18.7%]). Of these patients, 25 (28.4%) were T790M positive, among whom 24 (96.0%) received osimertinib. CONCLUSIONS: A third of patients received subsequent therapies on disease progression; only 30% of these were tested for EGFR-TKI resistance mutation, prior to receiving subsequent therapies. These results highlight the importance of choosing treatments in the 1 L setting that optimize benefits for patients with EGFR-mutated NSCLC.

Patient preferences for attributes of tyrosine kinase inhibitor treatments for EGFR mutation-positive non-small-cell lung cancer.

Aim: EGFR-tyrosine kinase inhibitors (TKIs) vary in efficacy, side effects (SEs) and dosing regimen. We explored EGFR-TKI treatment attribute preferences in EGFR mutation-positive metastatic non-small-cell lung cancer. Materials & methods: Patients completed a survey utilizing preference elicitation methods: direct elicitation of four EGFR-TKI profiles describing progression-free survival (PFS), severe SE risk, administration; discrete choice experiment involving 12 choice tasks. Results: 90 participated. The preferred profile (selected 89% of times) had the longest PFS (18 months) and the lowest severe SE risk (5%). Patients would need compensation with ≥three-times longer PFS for severe SEs. Patients would accept ≤7 months PFS reduction for oral treatments versus intravenous. Conclusion: Patients preferred longer PFS but were willing to accept reduced PFS for more favorable SEs and dosing convenience.

Structure and activation mechanism of the CHK2 DNA damage checkpoint kinase.

The CHK2 protein kinase is an important transducer of DNA damage checkpoint signals, and its mutation contributes to hereditary and sporadic cancer. CHK2 activation is triggered by the phosphorylation of Thr68 by the DNA damage-activated ATM kinase. This leads to transient CHK2 dimerization, in part through intermolecular phosphoThr68-FHA domain interactions. Dimerization promotes kinase activation through activation-loop autophosphorylation, but the mechanism of this process has not been clear. The dimeric crystal structure of CHK2, described here, in conjunction with biochemical and mutational data reveals that productive CHK2 dimerization additionally involves intermolecular FHA-kinase domain and FHA-FHA interactions. Ile157, mutated in the Li-Fraumeni cancer-predisposition syndrome, plays a central role in the FHA-kinase domain interface, explaining the lack of dimerization and autophosphorylation of this mutant. In the dimer, the kinase active sites face each other in close proximity, indicating that dimerization may also serve to optimally position the kinase active sites for efficient activation loop transphosphorylation.

Inhibition of fibroblast growth factor receptor 3-dependent lung adenocarcinoma with a human monoclonal antibody.

Activating mutations in fibroblast growth factor receptor 3 (FGFR3) have been identified in multiple types of human cancer and in congenital birth defects. In human lung cancer, fibroblast growth factor 9 (FGF9), a high-affinity ligand for FGFR3, is overexpressed in 10% of primary resected non-small cell lung cancer (NSCLC) specimens. Furthermore, in a mouse model where FGF9 can be induced in lung epithelial cells, epithelial proliferation and ensuing tumorigenesis is dependent on FGFR3. To develop new customized therapies for cancers that are dependent on FGFR3 activation, we have used this mouse model to evaluate a human monoclonal antibody (D11) with specificity for the extracellular ligand-binding domain of FGFR3, that recognizes both human and mouse forms of the receptor. Here, we show that D11 effectively inhibits signaling through FGFR3 in vitro, inhibits the growth of FGFR3-dependent FGF9-induced lung adenocarcinoma in mice, and reduces tumor-associated morbidity. Given the potency of FGF9 in this mouse model and the absolute requirement for signaling through FGFR3, this study validates the D11 antibody as a potentially useful and effective reagent for treating human cancers or other pathologies that are dependent on activation of FGFR3.