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Most EGFR exon 20 insertion (EGFRex20ins) driver mutations in non–small cell lung cancer (NSCLC) are insensitive to approved EGFR tyrosine kinase inhibitors (TKI). To address the limitations of existing therapies targeting EGFR-mutated NSCLC, mobocertinib (TAK-788), a novel irreversible EGFR TKI, was specifically designed to potently inhibit oncogenic variants containing activating EGFRex20ins mutations with selectivity over wild-type EGFR. The in vitro and in vivo activity of mobocertinib was evaluated in engineered and patient-derived models harboring diverse EGFRex20ins mutations. Mobocertinib inhibited viability of various EGFRex20ins-driven cell lines more potently than approved EGFR TKIs and demonstrated in vivo antitumor efficacy in patient-derived xenografts and murine orthotopic models. These findings support the ongoing clinical development of mobocertinib for the treatment of EGFRex20ins-mutated NSCLC.Significance:No oral EGFR-targeted therapies are approved for EGFR exon 20 insertion (EGFRex20ins) mutation-driven NSCLC. Mobocertinib is a novel small-molecule EGFR inhibitor specifically designed to target EGFRex20ins mutants. Preclinical data reported here support the clinical development of mobocertinib in patients with NSCLC with EGFR exon 20 insertion mutations.See related commentary by Pacheco, p. 1617.This article is highlighted in the In This Issue feature, p. 1601

Supplementary Tables (S1-6) and Figures (S1-6)

GSEA analysis of mobocertinib and T-DM1 treated tumors versus mobocertinib-only treated tumors Genes involved in "INTERFERON ALPHA RESPONSE", "INFLAMMATORY RESPONSE", "INTERFERON GAMMA RESPONSE", "IL2 STAT5 SIGNALING", "TNFA SIGNALING VIA NFKB" and "IL6 JAK STAT3 SIGNALING" pathways of HALLMARK gene sets.

No targeted treatments are currently approved for HER2 exon 20 insertion–mutant lung adenocarcinoma patients. Mobocertinib (TAK-788) is a potent irreversible tyrosine kinase inhibitor (TKI) designed to target human epidermal growth factor receptor 2 (HER2/ERBB2) exon 20 insertion mutations. However, the function of mobocertinib on HER2 exon 20 insertion–mutant lung cancer is still unclear. Here we conducted systematic characterization of preclinical models to understand the activity profile of mobocertinib against HER2 exon 20 insertions. In HER2 exon 20 insertion–mutant cell lines, the IC50 of mobocertinib was higher than poziotinib and comparable with or slightly lower than afatinib, neratinib, and pyrotinib. Mobocertinib had the lowest HER2 exon 20 insertion IC50/wild-type (WT) EGFR IC50 ratio, indicating that mobocertinib displayed the best selectivity profile in these models. Also, mobocertinib showed strong inhibitory activity in HER2 exon 20YVMA allograft and patient-derived xenograft models. In genetically engineered mouse models, HER2 exon 20G776>VC lung tumors exhibited a sustained complete response to mobocertinib, whereas HER2 exon 20YVMA tumors showed only partial and transient response. Combined treatment with a second antibody–drug conjugate (ADC) against HER2, ado-trastuzumab emtansine (T-DM1), synergized with mobocertinib in HER2 exon 20YVMA tumors. In addition to the tumor cell autonomous effect, sustained tumor growth control derived from M1 macrophage infiltration and CD4+ T-cell activation. These findings support the ongoing clinical development of mobocertinib (NCT02716116) and provide a rationale for future clinical evaluation of T-DM1 combinational therapy in HER2 exon 20YVMA insertion–mutant lung adenocarcinoma patients.Significance:This study elucidates the potent inhibitory activity of mobocertinib against HER2 exon 20 insertion–mutant lung cancer and the synergic effect of combined mobocertinib and T-DM1, providing a strong rationale for clinical investigation.

GSEA analysis of mobocertinib acquired resistant tumors versus response tumors Genes involved in "G2M CHECKPOINT", "MITOTIC SPINDLE" and "MTORC1 SIGNALING" pathways of HALLMARK gene sets.

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No targeted treatments are currently approved for HER2 exon 20 insertion–mutant lung adenocarcinoma patients. Mobocertinib (TAK-788) is a potent irreversible tyrosine kinase inhibitor (TKI) designed to target human epidermal growth factor receptor 2 (HER2/ERBB2) exon 20 insertion mutations. However, the function of mobocertinib on HER2 exon 20 insertion–mutant lung cancer is still unclear. Here we conducted systematic characterization of preclinical models to understand the activity profile of mobocertinib against HER2 exon 20 insertions. In HER2 exon 20 insertion–mutant cell lines, the IC50 of mobocertinib was higher than poziotinib and comparable with or slightly lower than afatinib, neratinib, and pyrotinib. Mobocertinib had the lowest HER2 exon 20 insertion IC50/wild-type (WT) EGFR IC50 ratio, indicating that mobocertinib displayed the best selectivity profile in these models. Also, mobocertinib showed strong inhibitory activity in HER2 exon 20YVMA allograft and patient-derived xenograft models. In genetically engineered mouse models, HER2 exon 20G776>VC lung tumors exhibited a sustained complete response to mobocertinib, whereas HER2 exon 20YVMA tumors showed only partial and transient response. Combined treatment with a second antibody–drug conjugate (ADC) against HER2, ado-trastuzumab emtansine (T-DM1), synergized with mobocertinib in HER2 exon 20YVMA tumors. In addition to the tumor cell autonomous effect, sustained tumor growth control derived from M1 macrophage infiltration and CD4+ T-cell activation. These findings support the ongoing clinical development of mobocertinib (NCT02716116) and provide a rationale for future clinical evaluation of T-DM1 combinational therapy in HER2 exon 20YVMA insertion–mutant lung adenocarcinoma patients. Significance: This study elucidates the potent inhibitory activity of mobocertinib against HER2 exon 20 insertion–mutant lung cancer and the synergic effect of combined mobocertinib and T-DM1, providing a strong rationale for clinical investigation.

No targeted treatments are currently approved for HER2 exon 20 insertion-mutant lung adenocarcinoma patients. Mobocertinib (TAK-788) is a potent irreversible tyrosine kinase inhibitor (TKI) designed to target human epidermal growth factor receptor 2 (HER2/ERBB2) exon 20 insertion mutations. However, the function of mobocertinib on HER2 exon 20 insertion-mutant lung cancer is still unclear. Here we conducted systematic characterization of pre-clinical models to understand the activity profile of mobocertinib against HER2 exon 20 insertions. In HER2 exon 20 insertion mutant cell lines, the IC(50) of mobocertinib was higher than poziotinib and comparable or slightly lower than afatinib, neratinib, and pyrotinib. Mobocertinib had the lowest HER2 exon 20 insertion IC(50) / WT EGFR IC(50) ratio, indicating that mobocertinib displayed the best selectivity profile in these models. Also, mobocertinib showed strong inhibitory activity in HER2 exon 20(YVMA) allograft and patient-derived xenograft models. In genetically engineered mouse models, HER2 exon 20(G776>VC) lung tumors exhibited a sustained complete response to mobocertinib, while HER2 exon 20(YVMA) tumors showed only partial and transient response. Combined treatment with a second antibody-drug conjugate (ADC) against HER2, ado-trastuzumab emtansine (T-DM1) synergized with mobocertinib in HER2 exon 20(YVMA) tumors. In addition to the tumor cell autonomous effect, sustained tumor growth control derived from M1 macrophage infiltration and CD4(+) T cell activation. These findings support the ongoing clinical development of mobocertinib (NCT02716116) and provide a rationale for future clinical evaluation of T-DM1 combinational therapy in HER2 exon 20(YVMA) insertion-mutant lung adenocarcinoma patients.

Characterizing in vivo cellular kinetics and biodistribution of chimeric antigen receptor T (CAR-T) cells is critical for toxicity assessment, nonclinical and clinical efficacy studies. To date, the standardized assay to characterize CAR-T cell distribution, expansion, contraction, and persistence profiles is not readily available. To overcome this limitation and increase comparability among studies, we have established a universal protocol for analysis. We established a duplexing ddPCR protocol for the CAR-T transgene and reference gene to normalize the genomic DNA input prepared from mouse blood and tissues. The high-throughput gDNA extraction method enabled highly reproducible gDNA extraction while eliminating labor-intensive steps. The investigational CAR-T cells were intravenously injected into immunodeficient mice bearing human colorectal cancer xenografts. The blood and tissue samples were collected to measure the cellular kinetics by ddPCR and flow cytometry. The standard curves were linear throughout the calibration range with acceptable intra- and inter-day precision and accuracy. The gDNA recovery study performed by spiking in the exo-gene plasmid DNA or CAR-T cells revealed that the recovery ranged from 60 to 100% in blood and tissue homogenates. The use of both units of copy/μg gDNA and copy/μL blood met the current regulatory requirement and allowed for a systematic understanding of CAR-T cell expansion and a direct comparison with the flow cytometry data. A standardized ddPCR assay, including automated gDNA extraction procedures, has been established for evaluating cellular kinetics and biodistribution in CAR-T cell therapies. Supplementary Information The online version contains supplementary material available at 10.1208/s12248-021-00560-6.

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Mouse syngeneic tumor models play a crucial role in the translationally oriented process of assessing the preclinical activity and mechanism of action of emerging novel immunotherapies and immunotherapy combinations. Recent advancements in fluorescent multiplex technology provide a potential opportunity to improve the evaluation and identification of specific subsets of mouse immune cells using a panel approach. This technology may provide the ability to complement more traditional means of immunophenotyping such as flow cytometry. We established Opal™ multiplex immunofluorescence (IF) assays for the evaluation of T-cells (CD4, CD8, CD25, FOXP3 and tumor marker) in mouse using a Leica Bond RX autostainer. Images were acquired by Vectra® Polaris™ multispectral scanner. HALO™ image analysis was used to assess identification, quantification, and spatial localization of the immune cell subsets within tumors. The multiplex IF assays were used to carry out baseline characterization of the T-cell panels in multiple syngeneic models (A20, CT26, 4T1, EMT6, B16F10, LLC1, Renca and MC38). Notably, integrated data from the Opal™ multiplex IF assay enabled characterization and validation of “hot vs. cold” tumors across multiple syngeneic models. In addition, using PAX5 as a tumor marker, the Opal™ multiplex IF assay T-cell panel was used to specifically evaluate A20 lymphoma tumors from BALB/c mice treated with TAK-981, an investigational, first-in-class small ubiquitin-like modifier (SUMO) inhibitor. Currently, TAK-981 is being evaluated in a first-in-human, Phase I trial (NCT03648372) in patients with relapsed/refractory lymphomas. In pre-clinical models, A20 tumors demonstrated a dose-dependent increase in cytotoxic T cell numbers in response to TAK-981, consistent with previously generated flow cytometry data in animal models and indicative of induction of an adaptive anti-tumor immune response by TAK-981. In conclusion, across a range of syngeneic mouse models, an Opal™ multiplex IF assay can successfully enable characterization of “hot vs. cold” tumors. In tumors derived from a specific syngeneic mouse model treated with a novel, first-in-class SUMO inhibitor, the Opal™ multiplex IF assay was also capable of recapitulating the characterization of the T-cell repertoire within the tumor microenvironment previously determined by flow cytometry. Together, this suggests multiplex IF can contribute to ongoing efforts driving early translational research in immuno-oncology. Citation Format: Omid Ghasemi, Agatha Zawadzka, Evan Luongo, Aimy Tse, Johara Chouitar, Cierra Casson, Michelle Ganno-Sherwood, Xingyue He, Patrick LeRoy, Kristina Xega, Stephan Grossman, Keli Song, Allison Berger, Katherine Galvin, Dennis Huszar, Vaishali Shinde. Establishment of automated multiplex immunofluorescence T-cell panel for baseline screening of syngeneic mouse models and evaluation of T-cell infiltration in A20 syngeneic tumors treated with TAK-981, a first-in-class SUMO inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-319.