NRG1 Fusions Research Articles

Genomic and Transcriptional Profiling of Chinese Melanoma Patients Enhanced Potentially Druggable Targets: A Multicenter Study

In contrast to Caucasian melanoma, which has been extensively studied, there are few studies on melanoma in Asian populations. Sporadic studies reported that only 40% of Asian melanoma patients could be druggable, which was much lower than that in Caucasians. More studies are required to refine this conclusion. Chinese melanoma patients (n = 469) were sequentially sequenced by DNA-NGS and RNA-NGS. The genomic alterations were determined, and potentially actionable targets were investigated. Patients with potential druggable targets were identified in 75% of Chinese melanoma patients by DNA-NGS based on OncoKB, which was much higher than in a previous Asian study. NRG1 fusions were first identified in melanoma. In addition, up to 11.7% (7/60) of patients in the undruggable group could be recognized as actionable by including RNA-NGS analysis. By comparing the fusion detection rate between DNA-NGS and RNA-NGS, all available samples after DNA-NGS detection were further verified by RNA-NGS. The use of RNA-NGS enhanced the proportion of druggable fusions from 2.56% to 17.27%. In total, the use of RNA-NGS increased the druggable proportion from 75% to 78%. In this study, we systemically analyzed the actionable landscape of melanoma in the largest Asian cohort. In addition, we first demonstrated how DNA and RNA sequential sequencing is essential in bringing clinical benefits to more patients with melanoma.

Profiling of gene fusion involving targetable genes in Chinese gastric cancer.

BACKGROUNDApproximately half of all new cases of gastric cancer (GC) and related deaths occur in China. More than 80% of patients with GC are diagnosed at an advanced stage, which results in poor prognosis. Although HER2-directed therapy and immune checkpoint inhibitors have been somewhat successful, new drugs are still needed for the treatment of GC. Notably, several gene fusion-targeted drugs have been approved by the United States Food and Drug Administration for solid tumors, including GC, such as larotrectinib for NTRK fusion-positive cancers and zenocutuzumab for NRG1 fusion-positive cancers. However, gene fusions involving targetable genes have not been well characterized in Chinese patients with GC.AIMTo identify the profile of fusions involving targetable genes in Chinese patients with GC using clinical specimens and determine the distribution of patients with gene fusion variants among the molecular subtypes of GC.METHODSWe retrospectively analyzed gene fusion events in tumor tissue samples from 954 Chinese patients with GC. Clinicopathological characteristics were obtained from their medical records. Genetic alterations, such as single nucleotide variants, indels, amplifications, and gene fusions, were identified using a targeted sequencing panel containing 825 genes. Fusions were validated by fluorescence in situ hybridization (FISH) using break-apart probes. The microsatellite instability (MSI) status was evaluated using MSIsensor from the targeted sequencing panel data. Tumor mutational burden (TMB) was calculated using the total number of nonsynonymous mutations divided by the total genomic targeted region. Chi-square analysis was used to determine the enrichment of gene fusions associated with the molecular subtypes of GC.RESULTSWe found that 1.68% (16/954) of patients harbored 20 fusion events involving targetable genes. RARA fusions (n = 5) were the most common, followed by FGFR2, BRAF, MET, FGFR3, RET, ALK, EGFR, NTRK2, and NRG1 fusions. Two of the RARA fusions, EML4-ALK (E6:E20) and EGFR-SEPTIN14 (E7:E10), have been identified in other tumors but not in GC. Surprisingly, 18 gene fusion events were previously not reported in any cancer types. Twelve of the eighteen novel gene fusions included complete exons encoding functional domains of targetable genes, such as the tyrosine kinase domain of receptor tyrosine kinases and the DNA- and ligand-binding domains of RARA. Consistent with the results of detection using the targeted sequencing fusion panel, the results of FISH (fluorescence in situ hybridization) confirmed the rearrangement of FGFR2 and BRAF in tumors from patients 04 and 09, respectively. Genetic analysis indicated that the fusion genes were significantly enriched in patients with ERBB2 amplification (P = 0.02); however, there were no significant differences between fusion-positive and fusion-negative patients in age, sex, MSI status, and TMB.CONCLUSIONWe characterized the landscape of fusions involving targetable genes in a Chinese GC cohort and found that 1.68% of patients with GC harbor potential targetable gene fusions, which were enriched in patients with ERBB2 amplification. Gene fusion detection may provide a potential treatment strategy for patients with GC with disease progression following standard therapy.

Plain language summary of NRG1 fusions in cancer: current knowledge and treatment with afatinib and other drugs

This plain language summary reports the findings of a recent review of NRG1 fusion-positive tumors. A gene fusion occurs when two genes join to create a new gene. This rearrangement of DNA can change the processes within normal cells and lead to cancer. One of these gene fusions involves the NRG1 gene. NRG1 fusions have been reported in several types of cancers. These are known as NRG1 fusion-positive cancers. One drug that has been studied in people with NRG1 fusion-positive cancer is called afatinib. People with several cancer types have received afatinib in clinical trials, and some people have responded to afatinib. Further studies are required to understand how effective afatinib and other treatments are for NRG1 fusion-positive cancer.

Abstract 1182: Molecular landscape and ErbB family signaling in NRG fusion NSCLC: Therapeutic implications for pan-ErbB family inhibitors

Abstract NRG1 gene fusions are rare clinically actionable somatic alterations identified in 0.1% - 0.2% of all tumors. Currently, there are no approved targeted therapies for patients with NRG1 fusion-positive cancer. Previous studies have demonstrated that NRG1 fusions signal through ErbB/HER family members and that HER2 inhibition has anti-tumor activity in NRG1 fusion driven cancers. However, NRG1 binds HER4 in addition to HER3, and the role of individual HER proteins and NRG1 fusion partners have not been fully elucidated. We hypothesized that HER2 and HER4 signaling may have important roles in NRG1 fusion driven cancers, and pan-HER targeting therapies may be more effective for NRG1 fusion positive cancers than HER2-specific inhibitors alone. To test this hypothesis, we investigated the frequency of the NRG1 fusions across cBioPortal and AACR project GENIE datasets and MD Anderson’s GEMINI databases and found that the incidence of NRG1 fusions in all tumor types was 0.1%. NRG1 fusions were observed in 3.3% of patients with cervical cancers and in 1.8% of breast cancers and 1.3% of non-small cell lung cancers. The most common fusion partner was CD74 (9%) and the second most common fusion partner was SLC3A2 (4%). To determine the role of ErbB signaling in NRG1-fusion positive cancers, we engineered Ba/F3 cells to express various ErbB/HER family members and the most common NRG1 fusion partners. Then, we evaluated different strategies of targeting NRG1-fusion positive cell lines using drugs that predominantly target EGFR, HER2, EGFR/HER2, dimerization, or drugs that are pan-HER inhibitors. In Ba/F3 cells, poziotinib, a pan-HER TKI, showed potent activity against cells harboring NRG1 fusions, with IC50 values of 0.19 - 0.36 nM and relative IC50 values (IC50 value of NRG1 fusion/IC50 value of WT EGFR) of 0.04 – 0.07. TKIs targeting predominately EGFR/HER2 (afatinib, dacomitinib and neratinib) we observed modest activity with IC50 values of 6.8 – 42 nM and relative IC50 values of 0.11 – 0.68. The IC50 values of HER2-specific TKIs (58 – 122 nM) were higher than EGFR/HER2 targeting TKIs, but the relative IC50 values (0.005 – 0.015) were lower than poziotinib. Among antibodies, targeting HER2 dimerization with pertuzumab had better single agent activity (IC50 values of 95 – 156 μg/ml) than trastuzumab which had no in vitro activity. Lastly, an additive effect was seen when trastuzumab was used in combination with pertuzumab, with IC50 values of 0.79 – 1.0 μg/ml, and poziotinib with trastuzumab and pertuzumab further potentiated activity. Taken together, these data suggest that pan-HER inhibition with agents such as poziotinib alone and in combination with inhibition of dimerization appears more effective than selective EGFR/HER2 inhibition and highlights the potential of combining agents with multiple mechanisms of HER family targeting. This pan-HER strategy merits further investigation in the clinic. Citation Format: Hibiki Udagawa, Jacqulyne P. Robichaux, Yasir Y. Elamin, Junqin He, Monique B. Nilsson, John V. Heymach. Molecular landscape and ErbB family signaling in NRG fusion NSCLC: Therapeutic implications for pan-ErbB family inhibitors [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 1182.

Abstract 1254: Actionable fusions detected by RNA-seq co-occur with PD-L1 expression and driver mutations in solid tumors patients

Abstract Background: Incorporating gene fusions into a comprehensive profile is critical not only because very effective therapies targeting oncogenic fusion proteins exist but they may also negate the response to therapy of an actionable SNV and InDel mutations. We examined the co-occurrence of actionable gene fusions detected by RNA-seq with actionable SNVs/InDels and with the immunotherapy response biomarker, PD-L1. Methods: In 2021, 5341 FFPE samples were analyzed by our clinical laboratory using a novel hybridization-based RNA sequencing assay. DNA (SNV/Indels) mutations were detected with a clinical grade NGS assay and PD-L1 protein expression was determined by IHC using an appropriate LDT or FDA approved assay. De-identified data were analyzed following an approved IRB protocol. Results: Of the 5341 patients tested for gene fusions only 0.7% were profiled with a comprehensive fusion detection panel for 250 clinically relevant fusion genes. Conversely, 67% of all patients were tested only for NTRK gene fusions. The prevalence of the following most relevant fusions was: ALK=3.16% (in particular EML4-ALK), NTRKs=0.85%, FGFR2=5.60%, RET=1.34% and ROS1=1.05%. Among NTRK fusions, NTRK3 was detected in 52.9% of the positive cases; in particular, dominant fusions are ETV6-NTRK3 (26%) and EML4-NTRK3 (20%). In the 163 fusion positive cases, 37 cases had available DNA mutation testing and PD-L1 expression testing. These patients presented 24 different actionable fusions, including ALK (2), FGFR1/2 (5), NTRK 1/2/3 (10), NRG1 (3), RET (3), and ROS1 (3) fusions. Interestingly, while 73% (27/37) of those tumors were PD-L1 positive, similar to the 75% found on the fusion negative samples, PD-L1 was positive in 88% (15/17) of the lung samples with pathogenic mutations from this subset. This was strikingly higher than the 45% (192/424) found in the fusion negative cohort. Finally, excluding TP53 mutations, NTRK fusions frequently co-occurred with RNF43, FBXW7, TERT promoter, and ARID1A pathogenic mutations. FGFR fusions co-occurred with BAP1, PBRM1, or KRAS mutations, which correlates with the fact that both FGFR2 fusions and swi/snf alterations are enriched in intrahepatic cholangiocarcinoma, where the FGFR fusions were detected. RET fusions co-occurred with ARID1A and TERT. ROS1 fusions co-occurred with SMARCA4 and KRAS pathogenic mutations simultaneously. NRG1 fusions co-occurred with ARID1A and FBXW7 mutations. EML4-ALK fusions co-occurred with FGFR2 and KMT2D variants of unknown significance. Conclusion: Actionable cancer-driving gene fusions were detected by RNA-sequencing and co-occurred with other biomarkers that can guide the selection of therapies, such as immune checkpoint inhibitors (ICI) and olaparib. The data suggest that gene fusion testing is an important addition to the genomic profiling for therapy selection in solid tumors. Citation Format: Miyoung Shin, Paris Petersen, Steven Lau-Rivera, Segun Jung, Sally Agersborg, Jacyln Hechtman, Fernando Lopez-Diaz, Vincent Funari. Actionable fusions detected by RNA-seq co-occur with PD-L1 expression and driver mutations in solid tumors patients [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 1254.

Abstract 78: Detection of gene fusions and exon skipping events in lung FFPE samples with Oncomine Precision Assay on Ion Torrent Genexus࣪ System

Abstract Introduction: Gene fusions and exon skipping events play an important oncogenic role in non-small cell lung cancer (NSCLC). Here we employed the Oncomine Precision Assay (OPA) for sequencing of 998 clinical research FFPE (Formalin-Fixed Paraffin-Embedded) lung samples using the Genexus࣪ integrated sequencing platform. The RNA assay strategy is aimed at providing a wide scope for studying known oncogenic fusions and exon skip variants, as well as a method for detection of novel fusion combinations and detection of fusions in a partner agnostic manner. We summarize the findings that include detected samples with oncogenic fusions in tyrosine kinase genes ALK, RET, ROS1 as well as MET exon14 skipping, and demonstrate the novel fusion detection capabilities of the panel. Methods: The Oncomine Precision Assay panel developed using the Ion AmpliSeq HD technology for use on both tissue and liquid biopsy samples to detect fusions with high sensitivity in low input RNA. The panel features 981 known fusion isoforms in 16 oncogenic drivers as well as assays for exon skipping and deletion in MET and EGFR. The amplicons are strategically designed around known fusion breakpoints and generate reads only if the variant is present. Results are assessed bioinformatically with a framework that includes detailed genomic annotations of the fusion breakpoint, and generates interpretable fusion calls and report in the Genxus࣪ software. In addition, the panel contains an algorithm for novel fusion detection, and 78 exon-junction amplicons for partner agnostic fusion detection in ALK, RET, NTRK1,2,3 and FGFR1,2,3 with an exon tiling expression imbalance assay. We used the Genexus࣪ instrument to sequence 998 unique lung FFPE samples and analyzed the results with the Genexus࣪ fusion analysis workflow. Results: A total of 998 unique lung FFPEs were sequenced, of which 906 (91%) resulted with >5000 aligned reads and at least 5 of the 7 RNA expression controls at the assay threshold. A total of 25 samples with ALK fusions were detected by either the targeted fusions or the expression imbalance assays. In addition, we detected 10 samples with RET fusions, 4 with FGFR3 fusions, 3 with ROS1 fusions, and additional single observations of NRG1, RSPO3 and FGFR1 fusions. Exon 14 skipping in MET was detected in 14 samples, of which we were able to detect a likely splice site variant SNV or indel at, or near the boundaries of exon 14, with the DNA assays of the panel. These variants were observed in a mutually exclusive set of 59 total samples (6.5% of the samples). Conclusions: We used the OPA panel for fusions and intragenic rearrangements that retains the simple workflow and fast turn-around time of previous Oncomine fusion, and demonstrated known and novel fusion detection as well exon skip variant detection capabilities in a research cohort of lung FFPE samples. For research use only. Not for use in diagnostic procedures. Citation Format: Amir Marcovitz, Jeoffrey Schageman, Jian Gu, Stephen Wunsch, David Chi, Paul D. williams, Scott P. Myrand, Fiona C. Hyland, Seth Sadis, Kelli S. Bramlett. Detection of gene fusions and exon skipping events in lung FFPE samples with Oncomine Precision Assay on Ion Torrent Genexus࣪ System [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 78.

Analysis of genomic alterations in pan-cancer from a large real-world Chinese population.

10568 Background: Effective targeted therapy sorely depends on comprehensive and precise genomic profiling. Besides, single nucleotide variations (SNVs) and InDels, gene fusions, as drivers and therapeutic targets of great importance, are not yet well characterized in Chinese patients. Methods: Formalin-fixed, paraffin-embedded (FFPE) tumor tissues from 1,384 pan-cancer patients were collected and sequenced using next-generation sequencing (NGS) targeting 40 cancer genes including SNV, fusion and assessing copy number variation (CNV) (AmoyDx HANDLE Classic Panel). qPCR and fluorescence in situ hybridization (FISH) were further applied to verify NGS detected fusion genes. Results: 1,384 patients were recruited including 890 lung cancers, 272 colorectal cancers, 174 gastric cancers, and 48 endometrial cancers. The prevalence of fusion genes (5.49%), including ALK-fusion (2.67%), ROS1-fusion (0.94%), RET-fusion (0.72%), NRG1-fusion (0.29%), and NTRK-fusion (0.07%), was nearly double the frequency of previously reported data from East Asians. Prevalence of fusion genes varied in different types of cancers. For instance, ALK (3.7%), ROS1 (1.5%), RET (1.0%) and NRG1 (0.2%) fusions were largely found in patients with non-small cell lung cancer (NSCLC), and were rarely detected in other cancer types. Further analysis of genomic alterations in fusion-positive patients revealed that, TP53 (21%) was the most frequently co-occurred mutated gene with ALK fusion, while RET fusions and ROS1 fusions were rarely accompanied by other mutated genes. In addition, two patients with RBPMS- NRG1 fusion were accompanied by BRAF and RB1 mutations, whereas no co-occurred mutation was found in patients with other partners of NRG1. Patients with inconsistent results of RNA-based NGS and FISH validation fusions are still being followed for treatment and survival, updated data will be available at the time of the presentation. Conclusions: Genomic alterations in real-world Chinese populations have specific characteristics, especially fusion genes. Further characterization of these variants is essential for clinics to guide appropriate targeted therapies.

The landscape of NRG1 fusions based on NGS in Chinese solid tumor patients.

e15073 Background: Neuregulin 1 gene ( NRG1) fusions are oncogenic in various tumor types and represent an emerging potential therapeutic target. In the previous reports, NRG1 fusions are overall rare (0.12%) in the Western population, being seen most frequently in NSCLCs. The incidence of NRG1 fusions in a variety of solid tumors based on NGS has been explored limitedly in Chinese patients. Methods: FFPE samples and matched peripheral blood were collected for NGS based 450 cancer genes panel assay and RNA panel assay.Somatic variants were analyzed following CAP/CLIA-certificated workflows, including Single Nucleotide Variant (SNV), Copy Number Variation (CNV), large insertion and deletions (Lindel) and gene rearrangements. Results: A total of 47 patients harboring NRG1 fusions and four of them were detected in RNA level. Non-small cell lung cancer (NSCLC) was the most common cancer type with the incidence of 0.19% (25/13089). The followed cancer types were bone sarcoma, breast carcinoma, pancreatic adenocarcinoma and colorectal carcinoma with the frequency of 0.30% (3/973), 0.16% (3/1850), 0.14% (3/2098) and 0.07% (3/4344) respectively. CD74 (10.1%), SLC34A2 (10.1%) and WRN (4.3%) represented the most common NRG1 fusion partners, other known partners contained CDH1, HMBOX1, ADAM5 and UNC5D. In total, 76.6% of the partners were novel partners, and the most common break points of NRG1 were intron5 and intron1. The 47 NRG1 fusion patients evenly distributed in female (49%) and male (51%), and 44.7% were at advanced stage (stage ≥ III). The median age was 57 years old (range, 8-86 years old) and the median TMB was 3.3 muts/Mb (range, 0-30.5). TP53 (48.9%), CDKN2A (14.9%) and ERBB2/FGFR1/MUC16/SMAD4 (12.8%) were the most common co-occurred mutated gene. In the alterations of ERBB2, 50% were amplifications and 2 patients were breast carcinoma. Only one patient showed ALK fusion and one showed FGFR1 fusion. Among all patients, 8.5% included p.G12X mutation of KRAS and 10.6% included alterations of EGFR with two L858R and two 19del mutations. Conclusions: This study revealed NRG1 fusions in approximately 0.19% of Chinese NSCLC tumor pts and presented the frequency of same common tumors. Also the genomic and clinical feature were analysed. NGS panel sequencing and OrigiFus algorithm showed the advantage of detecting NRG1 fusion and providing structure information of partners which could potentially guide more precise treatment options.

Efficacy and safety of zenocutuzumab, a HER2 x HER3 bispecific antibody, across advanced NRG1 fusion (NRG1+) cancers.

105 Background: NRG1 fusions are rare oncogenic drivers that have been identified in a variety of solid tumors. These proteins bind HER3, leading to HER2/HER3 heterodimerization and oncogenic transformation. Zenocutuzumab (MCLA-128; Zeno) is a Biclonics antibody that overcomes HER3 mediated NRG1 (or NRG1 fusion) signaling in tumor cells. Zeno docks on HER2, then binds to and blocks the NRG1 fusion-HER3 interaction and HER3 heterodimerization with HER2. Zeno is being evaluated in patients (pts) with NRG1+ cancer in the ongoing pivotal phase 2 part of the eNRGy study and early access program (EAP). Methods: Pts with NRG1 + solid tumors previously treated with or not candidates for standard therapy, aged ≥ 18 years, with ECOG PS ≤ 2, and measurable (RECIST 1.1) or evaluable disease, were enrolled. NRG1 fusions were determined by next generation sequencing (NGS) before enrollment. Zeno (750 mg IV Q2W) was administered until disease progression or unacceptable toxicity. Tumor imaging was conducted every 8 weeks. The primary endpoint is investigator (INV)-assessed objective response rate (ORR) and secondary endpoints include duration of response (DOR) and safety. Results: As of 12 Jan 2022, 99 pts with NRG1 + cancer (85 eNRGy, 14 EAP) were enrolled. Efficacy was assessed in 73 pts who received ≥ 1 dose of Zeno and who were enrolled as of 12 Jul 2021 to allow for the opportunity to have ≥ 6 months (mo) follow-up and met the criteria for the primary efficacy population. Median age was 59 y (range 22–84), 58% were female, 47%/53% pts had ECOG PS 0/1. Tumor types were non-small cell lung cancer (NSCLC; 41 pts), pancreas cancer (18 pts), breast cancer (5 pts), cholangiocarcinoma (3 pts), colorectal cancer (2 pts), and 4 other tumor types (1 pt each), with a median 2 prior systemic therapies (range 0-9). The most frequent fusion partners were CD74 (27%), SLC3A2 (18%), and ATP1B1 (15%). Among the 71 pts with measurable disease, the INV-assessed confirmed ORR was 34% (90% CI, 25;44), including responses in NSCLC (35%; 14/40 pts), pancreas cancer (39%; 7/18 pts), breast cancer (2/4 pts), and cholangiocarcinoma (1/3 pts). Responses occurred at the first tumor assessment in 20/24 responders, and are ongoing in 13 pts. Treatment is ongoing in 22 pts (13 NSCLC, 6 pancreas, 3 other solid tumors). Median DOR was 9.1 mo (95% CI, 5.2-12.0). Kaplan-Meier estimate of DOR rate at 6 mo was 70%. Among the 208 pts treated with Zeno monotherapy across all dosing schedules in the phase 2 setting, for individual adverse events irrespective of causality, grade ≥ 3 events were reported in <5% of pts. Conclusions: Zeno demonstrated robust and durable efficacy in pts with advanced NRG1+ cancer regardless of tumor histology. A well tolerated safety profile of Zeno was observed. Clinical trial information: NCT02912949.

CRESTONE: Initial efficacy and safety of seribantumab in solid tumors harboring NRG1 fusions.

3006 Background: NRG1 fusions are rare oncogenic drivers found in ̃0.2% of all solid tumors. These fusions elicit ERBB3/HER3 overactivation to drive tumor growth and cancer cell survival. Currently there are no approved targeted therapies for NRG1 fusion-positive tumors. Furthermore, patients (pts) with tumors harboring NRG1 fusions have poor outcomes with standard therapies. Seribantumab is a fully human anti-HER3 IgG2 monoclonal antibody that suppressed tumor growth in NRG1 fusion-driven preclinical models. Here, we present initial clinical data from the CRESTONE study (NCT04383210). Methods: CRESTONE is a Phase 2, global, multicenter, open-label study of seribantumab in adult pts with locally advanced or metastatic solid tumors harboring NRG1 fusions. A dose ranging phase established the RP2D as a 3g once weekly (QW) intravenous dose administered until treatment discontinuation criteria are met. In the expansion phase, cohort 1 will enroll at least 55 pts who had received at least one prior therapy and are naïve to ERBB-targeted therapy. Exploratory cohorts 2 or 3 will enroll pts previously treated with ERBB-targeted therapies and/or tumors harboring additional molecular alterations. The primary endpoint is objective response rate (ORR) by independent central review per RECIST v1.1. Initial data from cohort 1 pts who received seribantumab 3g QW with investigator (INV)-assessed response per RECIST v1.1 are reported. Results: By JAN-13-2022, 12 pts have received seribantumab 3g QW in cohort 1. Median age was 65 years (range 44–76), 67% were female, and median number of prior therapies was 1 (range 1–5). 92% (11/12) of pts had non-small cell lung cancer (NSCLC); 5 different NRG1 fusion partners ( ATP1B1, CD74, ITG B1, SDC4, SLC3 A2) were reported by local next-generation sequencing tests. Among 10 pts evaluable for INV-assessed response, the confirmed ORR was 30%, and the disease control rate was 90% (1 complete response, 2 partial responses, 6 stable disease, 1 progressive disease). 58% (7/12) of pts remain on study treatment, including 2 pts with NSCLC who achieved objective responses with an ongoing duration of response of 6 and 8.5 months. Seribantumab 3g QW was well tolerated with no drug discontinuations or dose reductions. Across all cohorts (n = 29), the most frequently (≥20%) reported treatment-related adverse events (TRAEs) were diarrhea (38%), fatigue (34%), and rash (24%), all were grade 1 or 2. One grade 3 TRAE of vomiting occurred; there were no Grade 4 or 5 TRAEs. Efficacy analysis is ongoing and updated efficacy data from evaluable pts in cohort 1 will be presented. Conclusions: Initial data indicate seribantumab induced durable responses in advanced solid tumors harboring NRG1 fusions and has a favorable safety profile. These data support the continued evaluation of seribantumab in NRG1 fusion-positive solid tumors in the ongoing CRESTONE study. Clinical trial information: NCT04383210.

Clinical and molecular characterization of fusion genes in colorectal cancer.

e15568 Background: Next-generation sequencing (NGS) based molecular profiling technologies have revealed several oncogenic fusion genes that are actionable with small molecule inhibitors leading to practice change, particularly in lung cancer. The molecular and clinical characteristics of these gene fusions are not well defined in colorectal cancer patients (CRC). In this study, we aimed to define clinical and molecular characteristics of fusion genes in patients with CRC who underwent molecular profiling. Methods: Molecular characteristics of tissue confirmed 917 CRC patients were retrieved from the Moffit Cancer Center Clinical Genomics Action Committee database. Patients’ demographic and clinicopathological features and treatment history were collected from the database. All fusion genes were shown by hybridization-based NGS computational algorithms that determined cancer‐related genes, including single‐nucleotide variations, indels, microsatellite instability (MSI) status. Results: Among a total of 917 patients, 24 patients with CRC (2.6%) were found to have at least one fusion gene with a total number of 26 pathogenic fusions. The gene fusions are shown in Table. The most common, potentially targetable, fusion genes in our cohort were (1) RET fusions 0.5% (5/917), (2) ALK fusions 0.4% (4/917), (3) ROS1 fusions 0.2% (2/917), (4) NTRK1 fusion 0.1% (1/917), (5) NRG1 fusion 0.1% (1/917). Fusion genes were more common in MSI-H CRC (N = 27), and 3 (11.1%) patients with MSI-H CRC were found to have fusion genes [(RET (2) and NTRK(1)]. Fusion genes were present in both RAS wild-type (54%; 13/24) and RAS mutant (46%; 11/24) tumors. Most patients were older than 50 years (75%, 18/24) and had left-sided tumor (61.1%) tumor. Conclusions: Fusion genes are rare events in CRC. While fusion genes seem to be more prevalent in MSI-H CRC, RAS status does not correlate with the frequency of fusion genes. Actionable RET and ALK/ROS gene fusion are more common than NTRK fusion genes in this cohort of CRC patients.[Table: see text]

CD74-NRG1 Fusions Are Oncogenic In Vivo and Induce Therapeutically Tractable ERBB2:ERBB3 Heterodimerization.

NRG1 fusions are recurrent somatic genome alterations occurring across several tumor types, including invasive mucinous lung adenocarcinomas and pancreatic ductal adenocarcinomas and are potentially actionable genetic alterations in these cancers. We initially discovered CD74-NRG1 as the first NRG1 fusion in lung adenocarcinomas, and many additional fusion partners have since been identified. Here, we present the first CD74-NRG1 transgenic mouse model and provide evidence that ubiquitous expression of the CD74-NRG1 fusion protein in vivo leads to tumor development at high frequency. Furthermore, we show that ERBB2:ERBB3 heterodimerization is a mechanistic event in transformation by CD74-NRG1 binding physically to ERBB3 and that CD74-NRG1-expressing cells proliferate independent of supplemented NRG1 ligand. Thus, NRG1 gene fusions are recurrent driver oncogenes that cause oncogene dependency. Consistent with these findings, patients with NRG1 fusion-positive cancers respond to therapy targeting the ERBB2:ERBB3 receptors.

Zenocutuzumab, a HER2xHER3 Bispecific Antibody, Is Effective Therapy for Tumors Driven by NRG1 Gene Rearrangements.

NRG1 rearrangements encode chimeric ligands that activate the ERBB receptor tyrosine kinase family. Here we show that targeting HER2 and HER3 simultaneously with the bispecific antibody Zeno leads to durable clinical responses in patients with NRG1 fusion-positive cancers and is thus an effective therapeutic strategy. This article is highlighted in the In This Issue feature, p. 1171.

Multiomic characterization to reveal a distinct molecular landscape in young-onset pancreatic cancer.

594 Background: Young-onset pancreatic cancer (YOPC; < 50 years at diagnosis) has been associated with male preponderance, extensive smoking history, and a trend towards improved survival compared with average-onset pancreatic cancer (AOPC; ≥70 years). However, the genomic and transcriptomic correlates underlying these clinical differences are incompletely understood. Using a large matched genomic-transcriptomic next-generation sequencing (NGS) dataset, we sought to characterize the distinct molecular landscape associated with YOPC compared with AOPC. Methods: A total of 2430 pancreatic ductal adenocarcinoma NGS samples (YOPC n = 292; AOPC n = 2138) with matched whole-transcriptome (NovaSeq) and DNA (NextSeq, 592-gene or NovaSeq, whole-exome) sequencing data were analyzed (Caris Life Sciences, Phoenix, AZ). Immune deconvolution was performed using the QuantiSeq pipeline. Limited clinical data precluded stage- and treatment-stratified comparisons between cohorts. Overall survival (OS) was obtained from insurance claims, and Kaplan-Meier estimates were calculated for age- and molecularly-defined cohorts. Significance was determined as FDR-corrected P-values (Q) < 0.05. Results: Of 2430 PDAC patients undergoing NGS, YOPC patients (median age 46 years) were more likely to be male (65% vs. 52%; P < 0.001) and current smokers (32% vs. 11%; P = 0.02) compared with AOPC patients (median age 75 years). YOPC patients had higher proportions of mismatch repair-deficient (MMR)/MSI-H (2.8% vs. 0.8%, P = 0.001), BRCA2-mutant (4.7% vs 2.1%, P = 0.009), and PALB2-mutant (1.4% vs 0.5%, P = 0.04) tumors compared with AOPC patients, while tumors in AOPC patients had more frequent SMAD4 (20.1% vs. 14.7%, P = 0.03), RNF43 (6.3% vs. 2.5%, P = 0.012), CDKN2A (24.8% vs. 19.2%, P = 0.04), and SF3B1 (2.7% vs. 0.7%, P = 0.04) mutations. YOPC patients also demonstrated lower HLA-DPA1 homozygosity (55.2% vs. 64.1%, Q < 0.05) vs. AOPC patients. Notably, YOPC patients demonstrated significantly lower incidence of KRAS-mutant (81.3% vs. 90.9%, Q < 0.01) tumors compared with AOPC patients. In the KRAS-wildtype subset (n = 225), YOPC tumors were more likely to be driven by NRG1 and MET fusions, while BRAF fusions were exclusively observed in AOPC patients. Computationally inferred immune deconvolution revealed enrichment of NK cell (Q = 0.04) and M2 macrophages (Q = 0.01) populations in YOPC tumors. There was an association with improved OS in YOPC patients with KRAS-wildtype (median 22.4 [YOPC- KRASWT] vs. 15.1 [AOPC- KRASWT] months, P = 0.02) but not KRAS-mutant (P = 0.28), tumors compared with AOPC patients. Conclusions: In this large real-world multi-omic characterization of age-stratified molecular differences in PDAC, YOPC is associated with a distinct molecular landscape compared with AOPC. These data reveal molecular features of YOPC with prognostic and therapeutic implications.

Efficacy of Pemetrexed-Based Chemotherapy in Advanced NSCLC Chinese Patients with NRG1 Fusions by TNA Sequencing: A Multicenter Study

Efficacy of Pemetrexed-Based Chemotherapy in Advanced NSCLC Chinese Patients with NRG1 Fusions by TNA Sequencing: A Multicenter Study

Abstract P201: Zenocutuzumab is an effective HER2/HER3 Biclonics® antibody in cancers with NRG1 fusions

Abstract Neuregulin 1 (NRG1) fusion proteins are oncogenic drivers in multiple cancer types, including non-small cell lung cancer, pancreas adenocarcinoma, and other solid tumors. NRG1 fusion proteins bind to HER3 and signal through HER2/HER3 heterodimers, leading to oncogenic transformation. Zenocutuzumab is an HER2/HER3 humanized IgG1 bispecific antibody that specifically and potently blocks NRG1 fusion-driven signaling of the heterodimeric complex. Zenocutuzumab binds via its anti-HER2 monovalent Fab arm to domain I of HER2. Docking of zenocutuzumab in this position increases the effective affinity of the anti-HER3 Fab arm, which binds to domain 3, a critical epitope that blocks binding of the HER3 ligand NRG1. Consequently, zenocutuzumab displaces NRG1 binding to HER3, even at high ligand concentrations, keeping HER3 in an inactive state and blocking HER2/HER3 heterodimerization and NRG1-mediated signaling. The clinical efficacy and safety of zenocutuzumab were recently demonstrated in patients with NRG1 fusion-driven cancers who were enrolled in the ongoing global multicenter eNRGy study and a global early access program NCT02912949 (J Clin Oncol 39;15_suppl; abstract 3003). Treatment with zenocutuzumab led to rapid and major radiologic tumor regression and biomarker responses in heavily pretreated patients with multiple NRG1 fusion-positive cancers with several different N-terminal fusion partners. Zenocutuzumab has been enhanced for antibody-dependent cell-mediated cytotoxicity (ADCC) to recruit and bolster immune effector cells to aid in tumor elimination. Here we explored the different Fc-mediated immune effector functions of zenocutuzumab. In several cancer cell lines, zenocutuzumab induced Fc-mediated dose-dependent ADCC and antibody-dependent cellular phagocytosis. Insertion of ATP1B1-NRG1 and SLC3A2-NRG1 into immortalized pancreatic ductal epithelial cells (H6c7) led to activation of the HER3 oncogenic signaling pathways including AKT. The H6c7-SLC3A2-NRG1 cells formed tumors when implanted in the subcutaneous flank of immune compromised mice (after about 10 weeks). Furthermore, a dependency of the transformed cell on this oncogene for growth and survival was also observed. Zenocutuzumab effectively inhibited proliferation of these NRG1 fusion-expressing, transformed cells. In addition, proteomic analysis showed that zenocutuzumab inhibited the HER3 and AKT-related downstream signaling pathways. In conclusion, these data provide strong mechanistic evidence supporting the clinical efficacy of zenocutuzumab in patients with NRG1 fusion-driven cancers. Citation Format: Jan Gerlach, Igor Odintsov, Ron Schackmann, Marc Ladanyi, Jeroen Lammerts van Bueren, Romel Somwar, Cecile Geuijen. Zenocutuzumab is an effective HER2/HER3 Biclonics® antibody in cancers with NRG1 fusions [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 P201.

Oncogenic KRAS promotes growth of lung cancer cells expressing SLC3A2-NRG1 fusion via ADAM17-mediated shedding of NRG1.

We previously found the SLC3A2-NRG1 (S-N) fusion gene in a lung adenocarcinoma specimen without known driver mutations and validated this in 59 invasive mucinous adenocarcinoma (IMA) samples. Interestingly, KRAS mutation coexisted (62.5%) in 10 out of 16 NRG1 fusions. In this study, we examined the role of mutant KRAS in regulating the S-N fusion protein in KRAS mutant (H358) and wild-type (Calu-3) cells. KRAS mutation-mediated increase in MEK1/2 and ERK1/2 activity enhanced disintegrin and metalloproteinase (ADAM)17 activity, which increased the shedding of NRG1 from the S-N fusion protein. The cleavage of NRG1 also increased the phosphorylation of ERBB2-ERBB3 heterocomplex receptors and their downstream signalling pathways, including PI3K/Akt/mTOR, even under activated KRAS mutation signalling. The concurrence of S-N fusion and KRAS mutation synergistically increased cell proliferation, colony formation, tumour growth, and the cells' resistance to EGFR kinase inhibitors more than KRAS mutation alone. Targeted inhibition of MEK1/2, and ADAM17 significantly induced apoptosis singly and when combined with each mutation singly or with chemotherapy in both the concurrent KRAS mutant and S-N fusion xenograft and lung orthotopic models. Taken together, this is the first study to report that KRAS mutation increased NRG1 cleavage from the S-N fusion protein through ADAM17, thereby enhancing the Ras/Raf/MEK/ERK and ERBB/PI3K/Akt/mTOR pathways. Moreover, the coexistence of KRAS mutant and S-N fusion in lung tumours renders them vulnerable to MEK1/2 and/or ADAM17 inhibitors, at least in part, due to their dependency on the strong positive loop between KRAS mutation and S-N fusion.

Neuregulin 1 Gene (NRG1). A Potentially New Targetable Alteration for the Treatment of Lung Cancer.

Simple SummaryTreatment in oncology has and will keep evolving into an agnostic approach where therapies are guided more towards the identification and targeting of genetic abnormalities and less by organ of origin of the cancer, as has been done for decades. With every genetic abnormality being identified as a target, the pharmaceutical development of medications targeting these genes has grown, leading to better survival rates, quality of life and a bigger interest in finding new targets. Lung cancer is one of the best examples where targetable genetic abnormalities have led to substantial survival differences compared to patients undergoing empirical conventional chemotherapy. Translocations in the neuregulin 1 gene (NRG1) are one of many gene fusions that are becoming clinically significant, and it has the potential to become a targetable gene with ongoing clinical trials already in Europe and the US. This review aims to portray the importance and latest developments regarding this new fusion in lung cancer treatment.Oncogenic gene fusions are hybrid genes that result from structural DNA rearrangements, leading to unregulated cell proliferation by different mechanisms in a wide variety of cancer. This has led to the development of directed therapies to antagonize a variety of mechanisms that lead to cell growth or proliferation. Multiple oncogene fusions are currently targeted in lung cancer treatment, such as those involving ALK, RET, NTRK and ROS1 among many others. Neuregulin (NRG) gene fusion has been described in the development of normal tissue as well as in a variety of diseases, such as schizophrenia, Hirschsprung’s disease, atrial fibrillation and, most recently, the development of various types of solid tumors, such as renal, gastric, pancreatic, breast, colorectal and, more recently, lung cancer. The mechanism for this is that the NRG1 chimeric ligand leads to aberrant activation of ERBB2 signaling via PI3K-AKT and MAPK cellular cascades, leading to cell division and proliferation. Details regarding the incidence of these gene rearrangements are lacking. Limited case reports and case series have evaluated their clinicopathologic features and prognostic significance in the lung cancer population. Taking this into account, NRG1 could become a targetable alteration in selected patients. This review highlights how the knowledge of new molecular mechanisms of NRG1 fusion may help in gaining new insights into the molecular status of lung cancer patients and unveil a novel targetable molecular marker.

The potential targeted drugs for fusion genes including NRG1 in pancreatic cancer.

Pancreatic cancer (PC) remains an incurable disease with few treatment options Recently, promising targets have been identified and novel therapeutic drugs are currently under development in KRAS wild-type PC. It has been reported that KRAS wild-type PC has the genomic alterations such as oncogenic derivers and kinase fusions. NRG1 fusion, which encodes the neuregulin 1 and is the main ligands for ERRB3, has been identified in approximately half of younger patients with PC with KRAS wild-type tumors by RNA sequencing. There are several promising targeted therapies for NRG1 fusion-positive tumors, such as EGFR-tyrosine kinase inhibitor, HER3, HER2 antibodies. BRAF, NTRK, and ALK fusion are also potentially actionable alterations in KRAS wild-type PC and novel therapies targeting certain aberrations have shown activity in clinical trials.

Abstract 935: Preclinical activity of seribantumab in gastrointestinal cancers with NRG1 fusions

Abstract Background. Oncogenic rearrangements of the neuregulin 1 gene (NRG1) consist of a 5' partner fused to a 3' NRG1 sequence that retains the EGF-like domain, and are found in 0.2% of solid tumors including lung, breast and gastrointestinal (GI) cancers. Carcinomas of GI origin, including pancreatic and cholangiocarcinoma, represent around 20% of solid tumors harboring NRG1 fusions and there is no approved therapy for this group of cancers. The chimeric NRG1 oncoproteins bind to HER3/ERBB3 leading to trans-activation of other ERBB family members and trigger a signaling cascade that culminates in oncogenesis. Although targeting HER3 represents a rational therapeutic strategy for cancers harboring NRG1 fusions, this has remained relatively unexplored for NRG1 fusion-positive GI malignancies. In this study we investigated the efficacy of the anti-HER3 monoclonal antibody seribantumab in preclinical models of NRG1-driven GI cancers. Methods. We developed models of isogenic pancreatic cancer cells with NRG1 fusions by lentiviral-mediated cDNA expression of ATP1B1-NRG1 and SLC3A2-NRG1 fusions in immortalized pancreatic ductal cells (H6c7). Seribantumab efficacy was evaluated in isogenic cell lines and in patient-derived xenograft (PDX) models of pancreatic adenocarcinoma (CTG-0943, APP-NRG1 fusion) and intrahepatic cholangiocarcinoma (CH-07-0068, RBPMS-NRG1 fusion). Western blotting analysis was used to evaluate protein phosphorylation. Expression of NRG1 fusions was confirmed by RT-PCR and NGS. Results. Expression of NRG1 fusions in H6c7 cells resulted in enhanced phosphorylation of HER3 and AKT and increased sensitivity to afatinib, as compared to empty vector control cells (H6c7-EV). Treatment of H6c7-SLC3A2-NRG1 cells with seribantumab resulted in a dose-dependent inhibition of HER3 and AKT phosphorylation. Seribantumab treatment of H6c7-ATP1B1-NRG1 and H6c7-SLC3A2-NRG1 cells resulted in dose-dependent inhibition of cell growth with IC50 values of 0.05 and 0.2 µM, respectively. In contrast, growth of H6c7-EV cells was much less sensitive to seribantumab (IC50 > 1µM). Tumor growth inhibition was observed after administration of seribantumab to PDX mouse models of pancreatic adenocarcinoma and intrahepatic cholangiocarcinoma. While seribantumab (5 mg and 10 mg per dose, BIW) was equally effective to the clinical equivalent dose of afatinib (5 mg/kg QD) in the cholangiocarcinoma PDX model, the two doses of seribantumab were more effective than afatinib in the pancreatic cancer PDX model, causing tumor shrinkage of up to 55% (23-77% range). There was no shrinkage of afatinib-treated pancreatic PDX tumors. Our results here suggest that seribantumab is effective at reducing tumor growth in preclinical models of gastrointestinal cancers with NRG1 fusions. These data support the use of seribantumab to treat GI and other cancers with NRG1 fusions in the ongoing phase 2 CRESTONE study (NCT#04383210). Citation Format: Igor Odintsov, Allan J. Lui, Paul R. Bloom, Morana Vojnic, Shawn Leland, Marc Ladanyi, Romel Somwar. Preclinical activity of seribantumab in gastrointestinal cancers with NRG1 fusions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 935.