High HER2 Expression Research Articles

Prevalence of low HER2 expression in breast cancer patients: An Indian experience.

e12543 Background: With the recent advent of trastuzumab deruxtecan and encouraging results of the DESTINY-Breast-04 trial, low HER2 expression has emerged as a clinically significant therapeutic biomarker. The prevalence of low HER2 expression is unexplored in Indian population. Methods: This is a single center ambispective observational study conducted over a period of 4 years (1st January 2019 to 31st January 2023) at Dr. B.R.A, I.R.C.H, All India Institute of Medical Sciences (AIIMS), New Delhi, India. Consecutive female breast cancer patients registered during the study period with available clinical-pathological details were eligible for study inclusion. The primary objective of the study was to assess the prevalence of HER2 low breast cancer. HER2 low was defined as having HER expression by immunohistochemistry (IHC) of 1+ or 2+ with no amplification of the HER2gene detected with a fluorescent in situ hybridization (FISH) assay. Patients were divided into three categories: HER-2 high (IHC3+, IHC2+/FISH+), HER-2 low (IHC 1+, IHC2+/FISH-), and HER2-0 (HER2 negative, IHC:0). Staging description of the cases were done as per anatomic TNM classification according to AJCC 7th edition. Results: A total of 2200 female breast cancer were registered during the study period, of which 1932 patients had available clinical-pathological details. Among 1932 patients, 600 patients (31%) had high HER2 expression and remaining 1332 patients had HER2 low/HER2-0 expression. Of the 1332 cases, the median age was 49 years (range 18–91 years). The stage distribution was stage I, 94 (7.06%); stage II, 409 (30.70%); stage III, 528 (39.64%); and stage IV, 301 (22.59%). Eight hundred patients (60.06%) were hormone positive, and 532 (39.94%) cases were hormone negative. The prevalence of HER2 low expression was 798 (59.9%). It was observed in 640 (80%) of hormone positive cases and 158 (29.69%) hormone-negative cases (p < 0.001). Rest 534 cases were HER2 0 [160 cases (20%) were hormone positive, and 374 cases (70.31%) were hormone negative]. Conclusions: This is the first study from India to document the prevalence of low HER2 expression in female breast cancers. We observed the prevalence to be around 60 % in our population, which is more in hormone receptor-positive breast cancer. The estimated prevalence is higher than that observed in Western population, and it underscores the need to systematically categorize these patients for therapeutic decision making at presentation.

Deep multi-omic analyses to identify targetable pathways in desmoplastic small round cell tumor (DSRCT) with opportunities for clinical intervention.

e22006 Background: DSRCT is an extremely rare and highly aggressive soft-tissue sarcoma affecting adolescents and young adults with male predominance. The 5-year overall survival is < 25% despite intensive multi-modality treatment including aggressive surgical resection, radiotherapy, chemotherapy, and targeted therapy. Therefore, more effective and innovative therapeutic options are urgently needed. Recent advances in genomic, epigenomic, proteomic, and immune profiling have uncovered a large number of therapeutic targets that are transforming the field of cancer medicine. This study aimed to identify novel targetable pathways in DSRCT using a deep multi-omics-based platform. Methods: Three patients with biopsy proven metastatic DSRCT were enrolled under an IRB-approved observational study within the “Serial Measurements of Molecular and Architectural Responses to Therapy” (SMMART) program at OHSU. Biopsies taken at enrollment were analyzed with targeted DNA sequencing, whole transcriptome sequencing, immunohistochemistry (IHC), NanoString GeoMx digital spatial profiling (DSP) multiplexed proteomics, single cell cyclic immunofluorescence (Cyc-IF), and reverse phase protein array (RPPA). Results: Multiple clinically relevant targets were identified, including HER2, androgen receptor (AR), elevated DNA damage response, and MAPK and mTOR signaling pathways. All three DSRCTs expressed HER2: clinical IHC identified HER2 low (1+) to HER2 equivocal (2+) expression; DSP analysis showed high HER2 and phospho-HER2 expression; and HER2 RNA expression was elevated compared to the TCGA sarcoma cohort. Two of the three patients displayed high AR protein expression, assessed by clinical IHC (90-100% positive cells) and DSP (top quartile compared to a 20 mixed-subtype breast cancer cohort). Strong evidence of DNA damage response was demonstrated at both RNA and protein levels, and RPPA revealed high PARP1, PAR, p-ATM, p-RPA32, and RAD51. Within cell signaling pathways, one DSRCT exhibited high total and phospho-ERK1/2 protein across all clinical and exploratory assays, while another patient displayed evidence of elevated mTOR pathway signaling by RPPA. Conclusions: Overall, this multi-omic analysis provided new insights into possible therapeutic targets for this rare and difficult to treat sarcoma subtype. Results from this study will be further validated in vivo using patient-derived xenograft (PDX) models, providing support for development of multiple early phase trials.

Molecular and clinical correlates of HER3 expression highlights its potential role as a therapeutic target in melanoma

Overexpression of the epidermal growth factor receptor family member HER3 (erbB3) has been implicated in several types of cancer and recently drugs targeting HER3 have shown promising clinical activity. In melanoma, HER3 overexpression has been linked to both metastasis formation and resistance to drug therapy in cell culture models. Here, we sought to characterise the expression of HER3 in 187 melanoma biopsies (149 cutaneous, 38 mucosal) using immunohistochemistry, as well as to analyse the association between HER3 expression and molecular, clinical and pathological variables. A subset of the cutaneous melanoma specimens was taken prior to treatment with immune checkpoint blockade therapy (pre-ICB) (n=79). HER3 expression (≥1+) was observed in 136 of 187 samples (∼73%). HER3 expression was found to be markedly lower in the mucosal melanomas, with 17 of the 38 tumours (∼45%) demonstrating no HER3 expression. In cutaneous melanomas, there was a negative association between HER3 expression and mutational load, a positive association with NRAS mutational status, and a trend of negative association with PD-L1 expression. In the pre-ICB cohort, an association was found between high HER3 expression (≥2+) and overall survival after anti-PD-1-based immunotherapy. Overall, our results indicate that HER3 is a promising therapeutic avenue in cutaneous melanoma worthy of further clinical evaluation.

Engineering a HER2-CAR-NK Cell Secreting Soluble Programmed Cell Death Protein with Superior Antitumor Efficacy

A new therapy strategy for relapsing patients who have received trastuzumab treatment urgently needs to be explored. HER2-specific chimeric antigen receptor (CAR)-expressing NK cells are being rapidly developed for solid tumor therapy, as they have many advantages over HER2-CAR-T cells. Endogenous soluble PD-1 (sPD-1) from the PD-1 extracellular domain blocks PD-1/PD-L1 interaction to promote cancer immunology. Herein, we engineered a new HER2-CAR-NK cell that co-expresses sPD-1 (designed as sPD-1-CAR-NK cells) and assessed its cytotoxic activities toward various cancer cells, activation of immunity and sPD-1 release in vitro and in mouse models bearing breast cancer cells with high HER2 expression, with or without trastuzumab resistance. We demonstrated that sPD-1-CAR-NK cells were able to release bioactive sPD-1, thereby enhancing the cytolytic activities of HER2-CAR-NK cells against HER2 and PD-L1 highly expressing target cells accompanied by increases in the secretion of perforin, granzyme B and IFN-γ. In vivo, sPD-1-CAR-NK cells had superior immunological anticancer efficacy compared to HER2-CAR-NK cells, and they had advantages over HER2-CAR-NK cells in the intraperitoneal injection of sPD-1. Moreover, the infiltration and activation of NK and T cells into tumor tissue were increased in mice with sPD-1-CAR-NK cells. There was no significant change in the body temperature, organ tissue and body weight in all groups except for the group with the PD-1 injection. Together, these data indicate that HER2-specific sPD-1-CAR-NK cells can transport sPD-1 into cancer tissues with high HER2 expression, further improving the efficacy of HER-CAR-NK cells without obvious side effects. sPD-1-CAR-NK is a promising cytotherapeutic agent for patients bearing HER2-positive breast cancer, including those with trastuzumab resistance.

Abstract 6337: Tri-specific CD3 x HER2 x HER2 antibodies in 1:2 format recognizing two different epitopes on HER2 demonstrate selective activity on human cancer cells with high HER2 expression

Abstract Human epidermal growth factor receptor 2 (HER2) is a membrane tyrosine kinase that was found to be amplified and overexpressed in various human cancers including breast cancer. Monoclonal antibodies targeting HER2 such as trastuzumab and pertuzumab provide good therapeutic benefits in patients with high HER2 expression tumors, however, not all patients respond to the treatment, and many suffer recurrence. There is still a large unmet need for targeted therapies to treat HER2 high expression tumors. T cell engaging antibodies that direct T cells to kill cancer cells by simultaneously binding to CD3 on T cells and tumor-associated antigens (TAA) on cancer cells have emerged as a promising new approach. Such therapeutics are potent, but safe use of them depends on selectivity of the TAA engaged. Though HER2 is highly overexpressed in ~ 20% of breast cancer, expression of HER2 is not restricted to cancer cells and present at low level in normal tissues. The capability of selectively targeting cancer cells over HER2 low expressing normal tissues is critical to the safety of CD3 x HER2 antibodies. It is noteworthy to mention that unlike antibody-drug conjugate (ADC) therapeutics, CD3 x HER2 antibodies might not be a good approach to target HER2 low/neg expression tumors due to the difference in mechanism of action. CMG6A19 is a 150 kD IgG-like tri-specific CD3 x HER2 x HER2 T cell-engaging antibody generated on Chimagen’s TRIAD platform. It is capable of simultaneously recognizing and binding to two different epitopes on HER2 proteins. Multiple human cell lines with different levels of HER2 expression were used as targets in the antibody-mediated hPBMC killing assays in vitro and in vivo, among which SK-BR-3, KPL-4 and BT474 have high HER2 expression as seen in HER2 positive cancers, HT55 and JIMT1 have medium level of HER2 expression, and PC3 and MCF7 have HER2 expression level that is close to in normal tissues. Conventional 1:1 IgG-like CD3 x HER2 bispecific antibodies were used as control. Results showed that CMG6A19 demonstrated higher tumor inhibition effect compared to control antibodies in SK-BR-3/KPL-4/BT474 models, meanwhile remarkably weaker effect in PC3/MCF7 models suggesting better safety in HER2 low expressing tissues. This selectivity of reactivity towards HER2 high expressing cells is likely due to the unique orientation of the antibody which allows better T cell activation when antigen abundance is high. Preliminary preclinical study in cynomolgus monkeys suggested that the antibody was well tolerated in monkeys at the dosage of 20 mpk and had a half-life that is comparable to conventional antibodies. CD3 x HER2 x HER2 tri-specific antibodies selectively showed potent anti-tumor activity on HER2 high expressing cells and good safety on HER2 low expressing cells. Current findings warrant further development in human. Citation Format: Jie Zhang, Xiaoqing Wang, Zhenhao Zhou. Tri-specific CD3 x HER2 x HER2 antibodies in 1:2 format recognizing two different epitopes on HER2 demonstrate selective activity on human cancer cells with high HER2 expression. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6337.

Abstract HER2-09: HER2-09 Multiomics Profiling Characterizes Distinct HER2-low Breast Cancer Subgroups in the East Asian Population

Abstract Background: The emergence of anti-HER2 antibody–drug conjugates (ADCs) gave rise to the concept of HER2-low breast cancer (BC). HER2-low BC, which refers to a subgroup of HER2-negative BC with relatively higher HER2 expression (defined as 1+ or 2+ by immunohistochemistry (IHC) staining, without ERBB2 amplification), represents a rather large part of all BCs. However, the molecular nature and internal heterogeneity of HER2-low breast cancer remain obscure, and little is known about the ethnic differences of HER2-low BC. These limitations prevent us from a more precise patient selection and better drug combination strategies in the era of ADCs. To provide a comprehensive and intensive landscape of HER2-low BCs, we characterized HER2-low BCs both clinically and molecularly, which may help clinicians to achieve a more precise clinical management of these patients. Patients and methods: We established a HER2-low BC cohort (N=441) in early-stage Chinese patients and included HER2-0 (N=114) and HER2-positive (N=181) tumors as auxiliary cohorts to characterize HER2-low breast cancers both clinically and molecularly. Whole-exome sequencing, copy number variation assays, RNA sequencing and isobaric quantitative proteomics were conducted to obtain multiomics data. We compared the clinicopathological and molecular features between HER2-low tumors and other HER2 status subgroups stratified and not stratified hormone receptor (HR) status to clarify the distinctness of HER2-low BCs. And we analyzed the internal heterogeneity and ethnic difference of HER2-low BCs by characterizing a distinct subgroup of patients with unique driving mechanisms. Results: HER2-low BCs showed different molecular manifestations from HER2-0 BCs in different HR subgroups. In the HR-negative subgroup, HER2-low BCs consisted of more non-basal-like subtypes than HER2-0 tumors (40.0% vs. 9.1%, P = 0.002), which was an East Asian-specific phenomenon absent in Western cohorts. Also, HR-negative HER2-low BCs showed significant internal molecular heterogeneity, of which basal-like tumors closely mimicked HER2-0 BCs, whereas non-basal-like tumors were similar to HER2-positive BCs. These non-basal-like tumors were mostly categorized as HER2-enriched and luminal androgen receptor (LAR) subtypes. These molecularly distinct tumors might be driven by frequent mutation in PIK3CA and overexpression of FGFR4 and PTK6, which may also serve as therapeutic targets. These results have also been proved in a triple negative breast cancer cohort we reported previously. In contrast, in the HR-positive subgroup, HER2-low BCs showed no large-scale molecular difference from HER2-0 BCs or internal heterogeneity. However, HER2-low patients showed significantly better distant metastasis-free survival than HER2-0 patients (P = 0.029), which might be attributed to the lower loss/deletion levels of 17q11.12 and 17q21.31 in HER2-low breast cancers, in which genes including NF1 and BRCA1 are located. Conclusions: We reported the largest single-center multiomics HER2-low BC cohort in East Asian hitherto, and revealed its molecular nature, internal heterogeneity and ethnic difference. Compared with HR-positive diseases, HER2-low BCs in the HR-negative subgroup were more likely to be a molecularly distinct entity from HER2-0 tumors. Furthermore, HR-negative HER2-low BC also accommodates higher internal heterogeneity, which was ethnicity-specific in our East Asian cohort and may infer a different treatment response. Our work emphasized the need of a more precise stratification within HER2-low BCs and across ethnic groups, which has also been inferred by the results in the subgroup analysis of DESTINY-Breast04 trial. Citation Format: Lei-Jie Dai, Ding Ma, Yi Xiao, Xi Jin, Song-Yang Wu, Ya-Xin Zhao, Han Wang, Wen-Tao Yang, Yi-Zhou Jiang, Zhi-Ming Shao. HER2-09 Multiomics Profiling Characterizes Distinct HER2-low Breast Cancer Subgroups in the East Asian Population [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr HER2-09.

Abstract HER2-13: HER2-13 Proficiency assessment of HER2-low breast cancer scoring with the Ventana PATHWAY 4B5 and Dako HercepTest HER2 assays and the impact of pathologist training

Abstract Background: Based on the results of the DESTINY-Breast04 study, the HER2-targeted antibody-drug conjugate trastuzumab deruxtecan (T-DXd) and the Ventana PATHWAY 4B5 companion diagnostic were recently approved by the US Food and Drug Administrated for the treatment and identification of patients with HER2-low (IHC2+/ISH- or IHC1+) (Modi et al. N Engl J Med 2022). The efficacy of T-DXd in HER2-low mBC highlights the need to distinguish lower ranges of HER2 IHC expression, which has been reported to be more challenging than scoring high HER2 expression (Fernandez et al. JAMA Oncol 2022). Here we report on current real-world HER2-low interpretation proficiency and the impact of training for participating pathologists in HER2-low scoring. Methods: Pathologists from laboratories across the US, EU, Japan, Australia, and Brazil were invited to use a digital pathology platform (Pathotrainer) to interpret HER2 digital images using ASCO/CAP 2018 scoring criteria. Two whole-slide imaging sample sets of representative study cases were compiled for Ventana PATHWAY 4B5 or Dako HercepTest (HcT) stained tumors. Another sample set (n = 25) was developed for a 4 hour virtual training session based on the ASCO/CAP 2018 guideline with some practical considerations. A steering committee (SC) of 8 pathology experts was formed to guide the study. Pathologists’ score was compared with a reference score as determined by independent review of 3 experts in HER2 pathology. Paired study cases (n = 14) considered challenging due to difficult-to-interpret staining patterns were reevaluated by the SC members. Concordance and efficacy of training were measured by Cohen’s weighted kappa (κ) coefficient, overall rater agreement (ORA), and receiver operating characteristic curve statistics. The primary endpoint was real-world concordance and ORA. The secondary endpoints were post-training concordance and ORA and correct identification of HER2 IHC 0 and HER2-low. Results: Pre-training baseline or real-world scores were taken by 77 pathologists in 14 countries (n = 49 for 4B5, n = 28 for HcT) and 74 pathologists completed post-training scores (n = 48 for 4B5, n = 26 for HcT). HER2 scoring proficiency of pathologists was high for both assays when assessed on ASCO/CAP binary HER2-negative and -positive status, irrespective of training (4B5: κ = 0.96, ORA =98.9.%; HcT: κ = 0.84, ORA = 94.3%) Concordance per ORA for the new 3-tier classification (HER2 IHC 0 vs HER2-low [IHC 2+/ISH- or IHC 1+] vs HER2-positive [IHC 3+ or IHC 2+/ISH+]) was greater than 80% for both assays at baseline and after training (see Table). In a subgroup analysis assessing training effect for 4B5 assay, concordance rates for HER2 IHC 0 were 74.6% at baseline and 89.2% after training (P < 0.001), and for HER2-low, NPA was 80.6% before and 91.1% after training (P < 0.001); there were no statistically significant changes after training for HcT (data not shown). Conclusions: Results from this real-world global study demonstrate that overall score concordance with a new category of HER2-low was above the 80% ORA benchmark for both 4B5 and HcT and is higher than previously reported (Fernandez et al. JAMA Oncol 2022). These data demonstrate pathologists’ ability to achieve an acceptable level of accuracy for identifying HER2 IHC 0 and HER2-low patients even after short-term training; however, additional training techniques and experience are needed to further improve accuracy. Acknowledgment Judy Yu, a former AstraZeneca employee, provided expertise and technical insights to support the study. Editorial Acknowledgment Under guidance of the authors, assistance in medical writing and editorial support was provided by Toinette Labuschagné, MSc, of ApotheCom, and was funded by Daiichi Sankyo. Funding This study was funded by Daiichi Sankyo and AstraZeneca. Table. Summary of Pathologist Concordance and Interobserver Variability Citation Format: Josef Rüschoff, Alexander Penner, Ian O. Ellis, M. Elizabeth H. Hammond, Annette Lebeau, Robert Y. Osamura, Frédérique Penault-Llorca, Federico Rojo, Neil Atkey, Andreas H. Scheel, Corrado D´Arrigo, Hans-Ulrich Schildhaus, Akira Moh, Chirag Desai, Giuseppe Viale. HER2-13 Proficiency assessment of HER2-low breast cancer scoring with the Ventana PATHWAY 4B5 and Dako HercepTest HER2 assays and the impact of pathologist training [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr HER2-13.

Co-expression of PD-L1 and oncogenic receptor tyrosine kinases HER2 and cMET is low in metastatic urothelial carcinoma.

533 Background: Activation of HER2 and cMET signaling has been implicated in the pathogenesis of urothelial carcinoma subsets, and the use of anti-PD-(L)1 agents is well established in this disease. Novel therapeutic combinations targeting both immune checkpoints and the cMET or HER2 pathways are currently under investigation in metastatic urothelial carcinoma (mUC). Co-expression of these molecular targets has not been characterized in mUC. We hypothesized that the rate of PD-L1 co-expression with cMET and HER2 may be low. Therefore, we sought to define tumor protein co-expression of PD-L1, HER2 and cMET in a cohort of mUC patients. Methods: Patients with mUC were identified from an institutional database. FFPE tumor specimens from metastatic sites and available paired primary tumors underwent immunohistochemical staining for PD-L1 (SP-142), cMET, and HER2 expression. High expression was defined using the following thresholds: PD-L1: >=5% of infiltrated immune cells; cMET: >=50% of tumor cells; HER2: score=3+ (complete membrane staining that is intense and >10% of tumor cells). Simple and Weighted Cohen’s kappa Statistics (κ) were utilized to assess the agreement in expression and co-expression between paired primary and metastatic samples. Cohen’s interpretation of the κ results is provided. Results: Specimens from 143 mUC patients were analyzed, including 79 with available paired primary tumors. In primary tumors (N=79), high expression of PD-L1, cMET, and HER2 was observed in 15.2%, 34.2%, and 12.7%, respectively. In metastatic samples (N=143), high expression of PD-L1, cMET and HER2 was detected in 9.8%, 41.3%, and 9.8%, respectively. Expression agreement rates between primary and metastatic specimens (n=79) were PD-L1: 79.7% (κ=0.09, slight agreement), cMET: 69.6% (κ=0.35, fair agreement), HER2: 84.8% (κ=0.17, slight agreement) and were driven by high prevalence of low expression. High PD-L1/cMET co-expression was observed in only 5.1% (n = 4) of primary and 4.9% (n =7) of metastatic specimens. High co-expression of PD-L1/HER2 occurred in only 3.8% (n=3) of primary samples and in no metastatic samples. The overall co-expression agreement rate between paired primary and metastatic samples was 55.7% (κ = 0.22, fair agreement) for PD-L1/cMET and 67.1% (κ = 0.06, slight agreement) for PD-L1/HER2. Importantly, however, agreements rates for high co-expression between primary and metastatic samples were very low (2.5% for PD-L1/cMET and 0% for PD-L1/HER2). Conclusions: Tumor co-expression of high cMET or HER2 and PD-L1 is low in this cohort of metastatic urothelial carcinoma patients. Furthermore, agreement of high co-expression between primary and metastatic sites is rare. These results suggest that investigational strategies combining immune checkpoint inhibition with either cMET or HER2 targeted agents in mUC may have limited synergistic activity.

Novel HER2-Targeted Peptide for NIR-II Imaging of Tumor.

Molecular targets serve a crucial role in drug development. Herein, we discovered a novel peptide that can specifically target the human epidermal growth factor receptor 2 (HER2) and thus named it Herceptide. In our study, Herceptide was conjugated to the near-infrared fluorescent dye indocyanine green (ICG) to obtain a probe, ICG-Herceptide. Importantly, specific binding to HER2 was revealed by molecular docking, surface plasmon resonance analysis, and competition assays. The probe showed high binding affinity (KD = 1.03 nM) and fast binding property (kon = 0.44 min-1). In vivo near-infrared window two (NIR-II, 1000-1700 nm) imaging in HER2-overexpressed SKOV3 tumor-bearing mice demonstrated a high tumor-to-normal tissue signal ratio (T/N = 7.3) at 8 h postinjection. In the blocking study, ICG-Herceptide coinjected with Herceptide only showed a weak tumor signal. In other HER2 high-expression tumors, such as non-small-cell lung cancer A549 and gastric cancer MKN45, the tumor-to-normal tissue signal ratios (T/N) were 4.1 and 4.7, respectively. In contrast, HER2 low-expression tumor MDAMB231 shows no imaging contrast between the tumor and normal tissues. Furthermore, tumor resection was successfully performed under the guidance of the ICG-Herceptide-based NIR-II imaging in subcutaneous SKOV3 mice models. The biocompatibility study indicated that the probe had no observable toxicity to cells and tissues. Overall, these results demonstrate that ICG-Herceptide is a promising optical probe for the diagnosis and localization of HER2-overexpressing tumors. Moreover, Herceptide is a novel HER2-targeting peptide and can be further used for developing theranostic agents.

Distinct Clinicopathological Features and Prognostic Values of High-, Low-, or Non-Expressing HER2 Status in Colorectal Cancer.

The encouraging effects of HER2-ADC in patients with HER2-low expression cancers indicated the classical classifications based on positive and negative HER2 might no longer be suitable. However, the biology and prognosis of colorectal cancer patients with different HER2 expression status were still not clear. This is a multi-center retrospective study that included patients with histologically confirmed colorectal cancer and determined HER2 status who received radical surgical resection. HER2 immunohistochemistry (IHC) 1+ and IHC 2+ groups were combined and defined as a HER2-low group because of the concordance of clinicopathological characteristics. As compared with the HER2-high group, both the HER2-zero and the HER2-low group had less tumor with perineural invasion (14.3%, 13.1% vs. 31.6%, p = 0.001 and p < 0.001), less stage III disease (41.8%, 39.9% vs. 56.1%, p = 0.044 and p = 0.022), more RAS/BRAF mutation (52.1%, 49.9% vs. 19.5%, p < 0.001 and p < 0.001) and better disease-free survival (DFS) (3y-DFS rate of 78.7%, 82.4% vs. 59.3%, p < 0.001 and p < 0.001). Multivariate analysis and propensity score matching also revealed that HER2-high expression was an independent prognostic factor of DFS. In conclusion, our study revealed that HER2-low colorectal cancer tumors are close to HER2-zero tumors, but different from HER2-high tumors. The routine examination of HER2 IHC is needed in early-stage colorectal cancer.

Abstract B027: PIK3CA hotspot mutations as biomarkers for prognosis and treatment prediction in low-risk postmenopausal breast cancer patients

Abstract The PIK3CA gene, encoding the p110α catalytic subunit of PI 3-kinase (PI3K), is mutated in more than 30% of breast cancers. Most mutations concentrate to the hotspots E542K and E545K and H1047R and are associated with hyperactivation of the phosphatidylinositol 3′-kinase/Akt pathway in vitro. The estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) (ER+/HER2-) breast cancers stand for more than 40% of the PIK3CA mutations where these constitute a new therapeutic target for endocrine-treatment resistant advanced breast cancers. Although PIK3CA is an oncogene, its mutations are associated with good prognosis. Here, we explored the prognostic and predictive role of PIK3CA hotspot mutations for low-risk postmenopausal breast cancer patients randomized to receive tamoxifen vs. no systemic treatment, followed for over 25 years and with extensive clinical records. Mutation analysis was performed using formalin-fixed paraffin-embedded tumors with digital droplet PCR (ddPCR). PIK3CA mutations were present in 35,6% of patients, predominantly within the ER+/HER2- subtype (49,8%) compared with the HER2+ and TNBC subtypes. The most frequent mutation found in all patients was H1047R (18%) followed by E545K (14%) and E542K (6%). Significant associations were found between all hotspot mutations and low grade, positive progesterone receptor (PR) expression, HER2 negative status, low Ki-67 (proliferation marker), and high expression score of a PIK3CA-mutation-associated gene module. Moreover, PIK3CA mutations were often found in patients with ultralow risk to develop distant recurrences according to the 70-gene signature. All PIK3CA mutations were coupled with longer distant recurrence-free interval (DRFI) in all patients in univariate and multivariable analysis after adjusting for tumor size, receptor status (ER, PR, HER2), tumor grade, Ki-67 and tamoxifen: HR multivariable (95% CI)=0.53 (0.28-0.98). In agreement with our previous results, PIK3CA mutations indicated good prognosis for patients with highly proliferative tumors (Ki-67>15%): H.R multivariable (95% CI)=0.15 (0.03-0.69) and high risk by the 70-gene signature: HR multivariable (95% CI)=0.14 (0.03-0.61) but not for low proliferative tumors (Ki-67<15%). In fact, PIK3CA mutations indicated adverse prognosis within those patients with ultralow risk where the registered survival was 100% in presence of the PIK3CA wild type genotype. PIK3CA mutations did not have predictive value for tamoxifen. In conclusion, PIK3CA mutations predominate within the ER+/HER2- subtype, are coupled with good clinical markers and longer DRFI in all patients and especially among aggressive tumors but not in ultralow risk patients. Further investigation will be needed to decipher the role of PIK3CA in patients with ultralow risk or indolent tumors who may present long-term relapses and specially benefit from PI3K inhibition. Citation Format: Carolin Jönsson, Zeinab Alkashaf, Josefine Sandström, Annelie Johansson, Tommy Fornander, Linda S. Lindström, Gizeh Perez Tenorio. PIK3CA hotspot mutations as biomarkers for prognosis and treatment prediction in low-risk postmenopausal breast cancer patients [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B027.

Her2 expression can predict the survival of patients with salivary duct carcinoma

Salivary duct carcinoma (SDC) is a high-grade malignant tumor that mainly develops in the salivary glands, and SDC patients have a 5-year survival rate of less than 50%. Thirteen SDC patients (11 male and 2 female, average age 67.2 years) with primary salivary gland carcinoma who received primary treatment in our department from 2005 to 2016. Although markers such as androgen receptors and gross cystic disease fluid protein-15 are effective in diagnosing SDC, there are no effective tumor-specific markers for prognosis prediction. Therefore, we investigated the expressions of human epidermal growth factor receptor 2 (Her2), Ki-67, EGFR, p16, P53 and PD-L1, and examined their prognostic effect. Multivariate analysis showed that high Her2 expression was an exacerbating prognostic factor. In the future, the use of molecular-targeted drugs and immune checkpoint inhibitors for salivary gland malignancies may become more frequent. Her2 expression could be used as a predictor of prognosis.

High SURF4 expression is associated with poor prognosis of breast cancer.

SURF4 has been suggested as an oncogene in cancer. However, the role of SURF4 in breast cancer has not been demonstrated yet. The data were obtained from TCGA database and 1104 patients were analyzed using bioinformatics analysis. SURF4 is significantly (P < 0.001) highly expressed in tumor. High expression of SURF4 was observed in T4, infiltrating ductal carcinoma, ER negative, PR negative, and HER2 positive, female, patients without lymph node metastasis, HER2 overexpression type, and deceased patients. As for characteristics correlated with high expression of SURF4, gender, histological type, molecular subtype, ER, PR, HER2, and vital status exhibited significant differences. The age (HR: 2.317, P < 0.001), stage (HR: 2.090, P < 0.001), and SURF4 expression (HR: 1.958, P = 0.005) exhibited independent prognostic value for overall survival (OS). Patients with high SURF4 expression, higher age, equivocal HER2, higher stages, or positive margin status had shorter OS. The stage (HR: 1.579, P < 0.001), and margin status (HR: 1.463, P = 0.006) exhibited independent prognostic value for relapse-free survival of breast cancer. High expression of SURF4 was first found in breast cancer. High SURF4 expression was observed in breast cancer tissue and cell. SURF4 promoted the proliferation and migration of 4T1 cells. SURF4 may be a biomarker in diagnosis and prognosis of breast cancer.

Biologic Evaluation of a Heterodimeric HER2-Albumin Targeted Affibody Molecule Produced by Chemo-Enzymatic Peptide Synthesis.

Targeted molecular radiation therapy is a promising emerging treatment modality in oncology, and peptide synthesis may shorten the time to reach the clinical stage. In this study, we have explored Chemo-Enzymatic Peptide Synthesis, or CEPS, as a new means of producing a therapeutic HER2 targeted Affibody® molecule, comprising a C-terminal albumin binding domain (ABD) for half-life extension and a total length of 108 amino acids. In addition, a DOTA moiety could be incorporated at N-terminus directly during the synthesis step and subsequently utilized for site-specific radiolabeling with the therapeutic radionuclide 177Lu. Retained thermodynamic stability as well as retained binding to both HER2 and albumin was verified. Furthermore, HER2 binding specificity of the radiolabeled Affibody molecule was confirmed by an in vitro saturation assay showing a significantly higher cell-bound activity of SKOV-3 (high HER2 expression) compared with BxPC3 (low HER2 expression), both in the presence and absence of HSA. In vivo evaluation in mice bearing HER2 expressing xenografts also showed specific tumor targeting as well as extended time in circulation and reduced kidney uptake compared with a HER2 targeted Affibody molecule without the ABD moiety. To conclude, we have demonstrated that CEPS can be used for production of Affibody-fusion molecules with retained in vitro and in vivo functionality.

Comparative Preclinical Evaluation of Peptide-Based Chelators for the Labeling of DARPin G3 with 99mTc for Radionuclide Imaging of HER2 Expression in Cancer.

Non-invasive radionuclide imaging of human epidermal growth factor receptor type 2 (HER2) expression in breast, gastroesophageal, and ovarian cancers may stratify patients for treatment using HER2-targeted therapeutics. Designed ankyrin repeat proteins (DARPins) are a promising type of targeting probe for radionuclide imaging. In clinical studies, the DARPin [99mTc]Tc-(HE)3-G3 labeled using a peptide-based chelator His-Glu-His-Glu-His-Glu ((HE)3), provided clear imaging of HER2 expressing breast cancer 2-4 h after injection. The goal of this study was to evaluate if the use of cysteine-containing peptide-based chelators Glu-Glu-Glu-Cys (E3C), Gly-Gly-Gly-Cys (G3C), and Gly-Gly-Gly-Ser-Cys connected via a (Gly-Gly-Gly-Ser)3-linker (designated as G3-(G3S)3C) would further improve the contrast of imaging using 99mTc-labeled derivatives of G3. The labeling of the new variants of G3 provided a radiochemical yield of over 95%. Labeled G3 variants bound specifically to human HER2-expressing cancer cell lines with affinities in the range of 1.9-5 nM. Biodistribution of [99mTc]Tc-G3-G3C, [99mTc]Tc-G3-(G3S)3C, and [99mTc]Tc-G3-E3C in mice was compared with the biodistribution of [99mTc]Tc-(HE)3-G3. It was found that the novel variants provide specific accumulation in HER2-expressing human xenografts and enable discrimination between tumors with high and low HER2 expression. However, [99mTc]Tc-(HE)3-G3 provided better contrast between tumors and the most frequent metastatic sites of HER2-expressing cancers and is therefore more suitable for clinical applications.

135O A multi-center phase Ib/II study of RC48-ADC combined with tislelizumab as neoadjuvant treatment in patients with HER2 positive locally advanced MIBC

Bladder cancer with HER2 high expression is related to pathological malignancy and poor prognosis. The standard care for muscle-invasive bladder cancer (MIBC) is neoadjuvant chemotherapy (NAC) followed by radical cystectomy. For HER2 positive MIBC, the efficacy of cisplatin- based NAC are unsatisfied. This study aims to evaluate the safety and efficacy of RC48-ADC, an anti-HER2 antibody conjugation, and tislelizumab as a novel neoadjuvant treatment in this population.

1246P Multicenter phase Ib/II study of second-line varlitinib and paclitaxel in patients with EGFR/HER2 co-expressing advanced gastric cancer (K-MASTER-13)

Varlitinib is a small-molecule inhibitor of the tyrosine kinases EGFR, HER2, and HER4. We present a phase Ib/II study to evaluate the safety and efficacy of varlitinib in combination with weekly paclitaxel in EGFR/HER2 co-expressing advanced gastric cancer (AGC) patients. (KCT0003583). AGC patients who had failed 1st line fluoropyrimidine-containing chemotherapy, with evidence of both EGFR and HER2 overexpression by IHC (≥1+), were enrolled. Varlitinib [Dose 1: 300 mg BID, Dose -1: 300mg intermittent dose] and paclitaxel (80 mg/m2 D1,8,15) were investigated every 4 weeks. After determining the DLT and RP2D in phase Ib, phase II part was conducted to evaluate the anti-tumor activity with a primary endpoint of PFS. In the phase Ib study, 9 subjects were enrolled at the dose 1 level of varlitinib 300mg, of which 6 patients were evaluable for safety per protocol. Among the 6 evaluable patients, there was 1 DLT of Grade 4 AST/ALT elevation. The RP2D was varlitinib 300mg once daily combined with paclitaxel (80mg/m2 on days 1, 8, and 15). The median follow-up duration of 9.3 months [95% confidence interval (CI), 6.1-12.5]. Among 27 patients treated with RP2D including 5 subjects from Phase Ib, median PFS and OS were 4.1 (95% CI, 2.4-4.9 months) and 7.9 months (95% CI, 3.3-12.5 months), respectively. Among 16 patients with measurable disease and administered with RP2D, confirmed response and disease control was observed in 5 patients (ORR=31.3%) and 14 patients (DCR=87.5%), respectively. No definite association between EGFR or HER2 high expression and the efficacy of varlitinib and paclitaxel could be determined. Most common any grade of adverse events (AEs) were neutropenia (51.8% and 22.2% of Grade 3), diarrhea (27.3%), and AST/ALT elevation (22.2% and 11.1% of Grade 3). No treatment related death or unexpected AEs resulting in treatment cessation were observed with the RP2D. Varlitinib combined with paclitaxel revealed manageable toxicities and antitumor activity in patients with EGFR/HER2 co-expressing AGC who progressed after first-line chemotherapy. Updated outcomes for ongoing patients and biomarker analysis will be presented.

Comparative Study on Clinicopathological Characteristics of Breast Cancer in Vietnam and Italy

Background: In Vietnam and Italy, breast cancer (BC) occurs in women more frequently than any other cancer. Vietnam has a substantially lower incidence of breast cancer than Italy, but a higher mortality rate. Most Vietnamese patients present to the hospital with severe tumors at the late stages of diagnosis. The purpose of this study was to compare clinicopathologic features, biomarkers, and subtypes of BC between Vietnamese women and Italian ones. Methods: The sample was collected from all Vietnamese patients undergoing surgery with the diagnosis of primary invasive breast carcinoma in Hue Central Hospital as well as Hue University Hospital in Vietnam during 1 year from April 2016 to April 2017, and from the same category of women in Sassari University Hospital, Italy during the year 2016. The study parameters in both groups consisted of age at diagnosis, tumor size, histologic grade, histologic type, axillary node status, stages of diagnosis, biomarkers (Estrogen Receptor - ER, Progesterone Receptor - PR, Ki-67 cell proliferation marker - Ki-67, Human epidermal growth factor receptor 2 - HER2), and molecular subtypes of BC. Results: 323 patients were collected in total (235 from Sassari, Italy, and 88 from Thua Thien - Hue province, Vietnam). Vietnamese patients were diagnosed at a younger age than Italian patients, at just 52.5 on average, while the figure for Italian was 62. The Vietnamese BC patients also had a bigger tumor in size, higher grade, more axillary node positivity as well as a later stage of disease in comparison with Italian ones. The proportion of ER-positive was higher in the Italian group than that in Vietnam (88.1 vs 55.7%). The high Ki-67 expression prevalence was significantly higher in Vietnamese patients compared with Italian (81.8 vs 45.1%). The HER2-positive rate in Vietnam was 33%, higher than that in Italy (8.1%). Histologic grade and cell proliferation index Ki-67 were significantly correlated with HER2 positivity in both groups. Conclusions: Vietnamese patients demonstrated more aggressive tumor features and worse prognostic biomarkers than Italian patients. The prevalence of HER2 positive and high Ki-67 expression in Vietnamese patients was considerably higher than in Italian patients. The remarkable differences in clinicopathological characteristics between the two populations suggest the diversity of biological tumor, ethnicity, and environment as well as the effectiveness of the screening program.

Improvement of specific aiming of X-ray radiotherapy on HER2-overexpressing cancerous cell lines by targeted delivery of silver nanoparticle

Human epidermal growth factor receptor 2 (HER2) as a member of epidermal growth factor receptor (EGFR) family is expressed in various kinds of malignant cells at a level higher than normal cells. Therefore, HER2 could be consider as a target for specific chemotherapy and selective ablation of cancerous cells. ZHER2 affibody as an engineered peptide with great affinity for HER2 receptor could be employed for specific targeting of cancer cells with high HER2 expression level. On the other hand, X-ray radiotherapy is one of the most prevalent approaches in cancer therapy and nanoparticles with high atomic number could enhance its efficiency. As an outcome, targeted delivery of these nanoparticles can increase intensity and focus of X-ray radiation on cancerous cells. In the current in vitro study, silver nanoparticles (AgNPs) in conjugations with ZHER2 affibody were investigated for enhancement of X-ray radiation therapy of HER2-positive cancerous cells originated from various kinds of malignancies. Cell lines with high expression of HER2 (SK-BR-3, HN-5, SK-OV-3) and also MCF-7 cell line with normal expression of HER2 were irradiated with X-ray in the presence of various concentrations of AgNPs or AgNP-ZHER2 conjugates. Morphology and size of prepared AgNPs and AgNP-ZHER2 were examined by atomic force microscopy (AFM) and dynamic light scattering (DLS). Success of conjugation was confirmed by UV–Vis spectroscopy and viability of treated cells was assessed by MTT assay. Our results showed that while sensitivity of four examined cell lines to AgNPs, AgNP-ZHER2, and X-ray radiation is different, but presence of AgNP-ZHER2 conjugate could significantly enhance efficiency of X-ray radiation in ablation of HER2-overexpressed cells at in vitro conditions.

Clinicopathological prognostic factors for gallbladder carcinoma: a retrospective study.

BackgroundGallbladder carcinoma (GBC) is an uncommon neoplasm with poor long-term survival. Worldwide the incidence rates vary according to geographic area. The multifactorial aetiology and the rarity of the disease limits the studies to improve outcomes in patients, since the treatment remains mostly surgical. The aim of this study was to identify clinicopathological prognostic factors for survival in patients with GBC submitted to surgery in our institution—a tertiary centre in Portugal. Also, to assess the expression of possible biomarkers (HER2, CD44 and ALDH1) in GBC, as well as the frequency of microsatellite instability (MSI) tumours.MethodsClinicopathological characteristics of 41 consecutive patients that underwent surgical resection for GBC (2008–2019) at our hospital were retrospectively reviewed. Clinicopathological factors were assessed and an immunohistochemical (IHC) analysis was done. Microsatellite stability (MSS) was considered if there was maintenance of nuclear expression of MLH1, MSH2, MSH6 and PMS2. Human epidermal growth factor receptor 2 (HER2) expression was evaluated according to the rules applied for gastric cancer and expression of CD44 and ALH1 was evaluated in order to detect cancer stem cells (CSC). Survival analysis was conducted using Kaplan-Meier and Cox regression was used to find prognostic factors.ResultsIncidence of GBC in our cohort of patients was 0.45%, most commonly affecting females. Median overall survival (OS) was 23 months with a 39.6% 5-year survival rate. Stage > II [hazard ratios (HR) =8.58; P=0.007], lymphovascular invasion (LVI) (HR =4.06; P=0.045) and hepatic resection (HR =0.288; P=0.034) independently influenced survival. HER2 positivity and high expression of CD44 or ADLH1 did not show significant influence in survival (P=0.649, P=0.868 and P=0.914, respectively), although HER2 and ALDH1 positive patients showed a tendency to a shorter OS, compared to negative patients. We found no relation between these biomarkers expression and disease stage. All analysed samples had MSS.ConclusionsGBC patients with a worse prognosis can be identified. The overexpression of HER2 could select patients for targeted therapy and prompt tissue sampling in unresectable patients.