Mobocertinib in Patients with EGFR Exon 20 Insertion-Positive Non-Small Cell Lung Cancer (MOON): An International Real-World Safety and Efficacy Analysis

EGFR exon 20 (EGFR Ex20) insertion mutations in non-small cell lung cancer (NSCLC) are insensitive to traditional EGFR tyrosine kinase inhibitors (TKIs). Mobocertinib is the only approved TKI specifically designed to target EGFR Ex20. We performed an international, real-world safety and efficacy analysis on patients with EGFR Ex20-positive NSCLC enrolled in a mobocertinib early access program. We explored the mechanisms of resistance by analyzing postprogression biopsies, as well as cross-resistance to amivantamab. Data from 86 patients with a median age of 67 years and a median of two prior lines of treatment were analyzed. Treatment-related adverse events (TRAEs) occurred in 95% of patients. Grade ≥3 TRAEs were reported in 38% of patients and included diarrhea (22%) and rash (8%). In 17% of patients, therapy was permanently discontinued, and two patients died due to TRAEs. Women were seven times more likely to discontinue treatment than men. In the overall cohort, the objective response rate to mobocertinib was 34% (95% CI, 24-45). The response rate in treatment-naïve patients was 27% (95% CI, 8-58). The median progression-free and overall survival was 5 months (95% CI, 3.5-6.5) and 12 months (95% CI, 6.8-17.2), respectively. The intracranial response rate was limited (13%), and one-third of disease progression cases involved the brain. Mobocertinib also showed antitumor activity following EGFR Ex20-specific therapy and vice versa. Potential mechanisms of resistance to mobocertinib included amplifications in MET, PIK3CA, and NRAS. Mobocertinib demonstrated meaningful efficacy in a real-world setting but was associated with considerable gastrointestinal and cutaneous toxicity.

NIPA (Nuclear Interaction Partner of ALK) Is Crucial for Effective NPM-ALK Mediated Lymphomagenesis

The NPM-ALK fusion kinase is expressed in 60% of systemic anaplastic large-cell lymphomas (ALCL). A Nuclear Interaction Partner of ALK (NIPA) was identified as a binding partner of NPM-ALK. To identify the precise role of NIPA for NPM-ALK-driven lymphomagenesis, we investigated various NPM-ALK+ cell lines and mouse models. Nipa deletion in primary mouse embryonic fibroblasts resulted in reduced transformation ability and colony formation upon NPM-ALK expression. Downregulating NIPA in murine NPM-ALK+ Ba/F3 and human ALCL cells decreased their proliferation ability and demonstrated synergistic effects of ALK inhibition and NIPA knockdown. Comprehensive in vivo analyses using short- and long-latency transplantation mouse models with NPM-ALK+ bone marrow (BM) revealed that Nipa deletion inhibited NPM-ALK-induced tumorigenesis with prolonged survival and reduced spleen colonies. To avoid off-target effects, we combined Nipa deletion and NPM-ALK expression exclusively in T cells using a lineage-restricted murine ALCL-like model resembling human disease: control mice died from neoplastic T-cell infiltration, whereas mice transplanted with Lck-CreTG/wtNipaflox/flox NPM-ALK+ BM showed significantly prolonged survival. Immunophenotypic analyses indicated a characteristic ALCL-like phenotype in all recipients but revealed fewer “stem-cell-like” features of Nipa-deficient lymphomas compared to controls. Our results identify NIPA as a crucial player in effective NPM-ALK-driven ALCL-like disease in clinically relevant murine and cell-based models.

Treatment outcome of atypical EGFR mutations in the German National Network Genomic Medicine Lung Cancer (nNGM)

BACKGROUND

Atypical EGFR mutations occur in 10-30% of NSCLC patients with EGFR mutations and their sensitivity to classical EGFR-tyrosine kinase inhibitors (TKI) is highly heterogeneous. Patients harboring one group of uncommon, recurrent EGFR mutations (G719X, S768I, L861Q) respond to EGFR-TKI. Exon 20 insertions are mostly insensitive to EGFR-TKI but display sensitivity to exon 20 inhibitors. Clinical outcome data of patients with very rare point and compound mutations upon systemic treatments are still sparse to date.

PATIENTS AND METHODS

In this retrospective, multi-center study of the national Network Genomic Medicine (nNGM) in Germany, 856 NSCLC cases with atypical EGFR mutations including co-occuring mutations were reported from 12 centers. Clinical follow-up data after treatment with different EGFR-TKI, chemotherapy and immune checkpoint inhibitors were available from 260 patients. Response to treatment was analyzed in three major groups: (1) uncommon mutations (G719X, S7681, L861Q and combinations), (2) exon 20 insertions and (3) very rare EGFR mutations (very rare single point mutations, compound mutations, exon 18 deletions, exon 19 insertions).

RESULTS

Our study comprises the largest thus far reported real-world cohort of very rare EGFR single point and compound mutations treated with different systemic treatments. We validated higher efficacy of EGFR-TKI in comparison to chemotherapy in group 1 (uncommon), while most exon 20 insertions (group 2) were not EGFR-TKI responsive. In addition, we found TKI sensitivity of very rare point mutations (group 3) and of complex EGFR mutations containing exon 19 deletions or L858R mutations independent of the combination partner. Notably, treatment responses in group 3 (very rare) were highly heterogeneous. Co-occurring TP53 mutations exerted a non-significant trend for a detrimental effect on outcome in EGFR-TKI treated patients in groups 2 and 3 but not in group 1.

CONCLUSIONS

Based on our findings we propose a novel nNGM classification of uncommon EGFR mutations.

Treatment outcome and functional characterization of uncommon EGFR mutations in the German National Network Genomic Medicine Lung Cancer (nNGM)

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Background: The nNGM centralizes molecular diagnostics, treatment recommendations and follow-up reporting in NSCLC in Germany. Uncommon EGFR mutations pose a clinical challenge because they comprise a heterogenous group and analyses of treatment outcome are still scarce. Here, we analyzed follow-up data of patients with rare EGFR mutations and performed functional characterization of recurrent mutations with unknown function. Methods: This multicenter, retrospective analysis of uncommon EGFR mutations (excluding L858R-, T790M mutations and exon 19 deletions) includes stage IV patients with NSCLC from 12 nNGM centers. We categorized EGFR-mutations into 3 groups: uncommon EGFR mutations with known driver function, for instance E709X, G719X, S768I and L861Q (group 1), exon 20 insertions (group 2) and all other very rare mutations (group 3). Functional characterization of unknown mutations was performed by insertion mutagenesis in Ba/F3 cells and monitoring of growth factor-independent proliferation. Results: In total, 834 cases with uncommon EGFR mutations were reported. Follow-up data after EGFR-TKI (Erlotinib, Gefitinib, Afatinib and Osimertinib), chemotherapy and/or mono-PD(L)1 blockade was available for 252 patients. Mean progression free survival (mPFS) on EGFR-TKIs vs. chemotherapy was 6.6 months vs. 5.0 months (HR 0.54, 95%CI 0.35 to 0.81, P =.003) in group 1 (n = 84), and 6.7 months vs. 3.4 months (HR 0.66, 95%CI 0.47 to 0.92, P =.015) in group 3 (n = 104). Mono-anti-PD(L1) blockade was not superior to chemotherapy (group 1, mPFS 3.0 months, HR 1.32, 95% 0.55 – 3.15, P =.535 and group3, mPFS 4.3 months, HR 1.02, 95% CI 0.64 – 1.62, P = 0.951). Exon 20 insertions (group 2, n = 63) did not benefit from EGFR-TKIs or anti-PD(L1) blockade vs. chemotherapy. Overall survival (OS) analysis (n = 218) following chemotherapy (56%) or EGFR-TKI treatment (44%) showed median OS (mOS) of 18.0 months vs. 13.9 months in patients treated with EGFR-TKI and chemotherapy, respectively in group 1 (HR 0.97, 95%CI 0.54 to 1.75, P =.929). In group 3 patients treated with EGFR-TKI and chemotherapy had a mOS of 35.4 months vs. 12.0 months, respectively (HR 0.59, 95%CI 0.35 to 1.01, P =.056). In the Ba/F3 system we could identify 8 recurrent driver and 12 non-driver mutations with a clinically applicable assay turnaround time of 4 weeks to inform clinical decision-making in the future. Conclusions: This real-world dataset confirms that patients with group 1(uncommon) EGFR mutations benefit from EGFR-TKIs and indicates that mono-anti PD(L)1 blockade is not superior to chemotherapy. Furthermore, patients with very rare EGFR mutations (group 3) also experienced a PFS benefit from EGFR-TKI compared to chemotherapy while immune therapy was not beneficial.