anti-HER2 Antibody Research Articles

Novel Therapies and Strategies to Overcome Resistance to Anti-HER2-Targeted Drugs.

Simple SummaryDrug resistance is the “Achilles’ heel” in current oncology. In this sense, the clinical management of HER2 breast carcinomas (tumors with overexpression/amplification of the ErbB2/HER2 oncogene) is still a challenge. Although a variety of anti-HER2 therapies (anti-HER2 antibodies, antibody–drug conjugates, and tyrosine kinase inhibitors) are available for these patients, the frequent appearance of innate and acquired tumor resistance to these treatments creates an urgent need to develop new and more effective therapeutic approaches. In this review, we discuss the most relevant clinical and pre-clinical advances in therapeutic strategies aimed at overcoming drug resistance in HER2 breast cancer patients in different stages of the disease.The prognosis and quality of life of HER2 breast cancer patients have significantly improved due to the crucial clinical benefit of various anti-HER2 targeted therapies. However, HER2 tumors can possess or develop several resistance mechanisms to these treatments, thus leaving patients with a limited set of additional therapeutic options. Fortunately, to overcome this problem, in recent years, multiple different and complementary approaches have been developed (such as antibody–drug conjugates (ADCs)) that are in clinical or preclinical stages. In this review, we focus on emerging strategies other than on ADCs that are either aimed at directly target the HER2 receptor (i.e., novel tyrosine kinase inhibitors) or subsequent intracellular signaling (e.g., PI3K/AKT/mTOR, CDK4/6 inhibitors, etc.), as well as on innovative approaches designed to attack other potential tumor weaknesses (such as immunotherapy, autophagy blockade, or targeting of other genes within the HER2 amplicon). Moreover, relevant technical advances such as anti-HER2 nanotherapies and immunotoxins are also discussed. In brief, this review summarizes the impact of novel therapeutic approaches on current and future clinical management of aggressive HER2 breast tumors.

Population pharmacokinetics of zanidatamab, an anti-HER2 biparatopic antibody, in patients with advanced or metastatic cancer.

To characterize the pharmacokinetics (PK) of zanidatamab including evaluation of the impact of intrinsic and extrinsic patient factors. To investigate alternative dosing regimens to improve caregiver convenience and reduce zanidatamab wastage. Serum zanidatamab concentrations were obtained from 305 patients with advanced or metastatic breast cancer, gastroesophageal adenocarcinoma (GEA), biliary tract cancer, and other HER2-expressing cancers from four ongoing phase I and II clinical trials. Zanidatamab PK were described using population methods. The exposure of alternative dosing regimens and the impact of dose delay was estimated by model simulation. A two-compartment model with parallel linear and nonlinear clearance from the central compartment adequately described zanidatamab PK. At the recommended dose regimens of 20mg/kg Q2W and 30mg/kg Q3W, zanidatamab clearance was primarily linear at steady state. At steady state, 30mg/kg Q3W zanidatamab returns within 10% of the steady state trough after 2 subsequent doses following either a 1-week or 2-week dose delay. Statistically significant covariates included in the final model were body weight, sex, albumin, GEA cancer type, baseline tumor size, and presence of post-baseline anti-drug antibodies, all of which resulted in less than 30% impact on exposure. Model simulation predicts weight-based and two-tiered flat dosing will result in similar exposure and variability. The identified significant covariates were not considered clinically meaningful. Both weight-based (30mg/kg Q3W) and two-tiered flat dosing (1800/2400mg Q3W, 70kg threshold) strategies are expected to provide similar exposures of zanidatamab.

Cost-effectiveness analysis of trastuzumab deruxtecan versus trastuzumab emtansine for HER2-positive breast cancer.

Background: The DESTINY-Breast03 clinical trial demonstrated that trastuzumab deruxtecan (T-DXd) outperformed trastuzumab emtansine (T-DM1) in progression-free survival (PFS) in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (mBC). Considering the excessive cost of antibody-drug conjugates, the clinical value of T-DXd must be assessed by both its efficacy and cost. We compared the cost-effectiveness of T-DXd and T-DM1 for patients with HER2-positive mBC pretreated with anti-HER2 antibodies and a taxane from the perspectives of the United States (US) and China. Methods: A comprehensive Markov model based on the DESTINY-Breast03 phase III randomized clinical trial was used to compared the cost and effectiveness of T-DXd and T-DM1 for HER2-positive mBC. Data on direct medical cost and utilities were collected from published literatures. The recorded data included the costs, quality-adjusted life-year (QALY), incremental cost-effectiveness ratio (ICER) and incremental net-health benefit (INHB). Sensitivity analysis was conducted to measure the potential uncertainty due to parameter variability. Additional subgroup cost-effectiveness analysis was performed. Results: Treatment of HER2-positive mBC with T-DXd gained 0.73 QALYs compared with T-DM1 strategy. The incremental cost was $59,942 in the US, with an ICER of $ 82,112/QALY and an INHB of 0.33 QALYs, respectively. In China, the incremental cost of T-DXd versus T-DM1 was $222,680, with an ICER of $305,041/QALY and a negative INHB of -5.18 QALYs. At willingness-to-pay (WTP) threshold of $150,000/QALY in the US and $37,653/QALY in China, the probability of T-DXd as the dominant option was 77.5 and 0.1%, respectively. The unit price of T-DXd greatly influenced the results according to one-way sensitivity analysis. To meet the 50% or 90% chance of being cost-effective, the estimated cost of T-DXd would need to be less than $17.24/mg and $12.06/mg in China, respectively. Conclusion: T-DXd is more cost-effective than T-DM1 for patients with HER2-positive mBC in the US, but not in China at current drug prices.

Targeted immunotherapy against distinct cancer-associated fibroblasts overcomes treatment resistance in refractory HER2+ breast tumors

About 50% of human epidermal growth factor receptor 2 (HER2)+ breast cancer patients do not benefit from HER2-targeted therapy and almost 20% of them relapse after treatment. Here, we conduct a detailed analysis of two independent cohorts of HER2+ breast cancer patients treated with trastuzumab to elucidate the mechanisms of resistance to anti-HER2 monoclonal antibodies. In addition, we develop a fully humanized immunocompetent model of HER2+ breast cancer recapitulating ex vivo the biological processes that associate with patients’ response to treatment. Thanks to these two approaches, we uncover a population of TGF-beta-activated cancer-associated fibroblasts (CAF) specific from tumors resistant to therapy. The presence of this cellular subset related to previously described myofibroblastic (CAF-S1) and podoplanin+ CAF subtypes in breast cancer associates with low IL2 activity. Correspondingly, we find that stroma-targeted stimulation of IL2 pathway in unresponsive tumors restores trastuzumab anti-cancer efficiency. Overall, our study underscores the therapeutic potential of exploiting the tumor microenvironment to identify and overcome mechanisms of resistance to anti-cancer treatment.

Trends in anti-HER2 drugs consumption and influencing factors.

BackgroundHuman epidermal growth factor receptor 2 (HER2) inhibitors have been approved to treat various cancers with HER2 amplification. The Chinese government has made great efforts to improve the availability and affordability of these drugs. This study aimed to analyze the trends in anti-HER2 drug consumptions in Nanjing from 2012 to 2021, and explore influencing factors.MethodsData about use of anti-HER2 drugs in 2012–2021 were extracted from Jiangsu Medicine Information Institute. Six types of anti-HER2 drugs were included. Drug consumption was expressed as defined daily doses (DDDs) and expenditure. Time series analysis was adopted to find trends in consumption, while interrupted time series was used in analyzing the impact of policy on consumption. The correlation between DDDs and defined daily cost (DDC) was analyzed by Pearson's correlation test.ResultsThe DDC, DDDs, and expenditure of anti-HER2 drugs changed little from 2012 to 2016. The DDC decreased intermittently, while the DDDs and expenditure of these drugs grew continuously from 2017 to 2021. The anti-HER2 monoclonal antibodies contributed to the majority of total consumption in 2012–2019. The DDDs of anti-HER2 tyrosine kinase inhibitors surpassed the DDDs of monoclonal antibodies in 2020–2021. Trastuzumab was the predominantly prescribed drug in 2012–2019, but the DDDs of pyrotinib surpassed the DDDs of trastuzumab in 2020–2021. The ln value of DDC or self-paid DDC of trastuzumab was negatively correlated with the ln value of its DDDs. The national health insurance coverage (NHIC) and national drug price negotiation policy about anti-HER2 drugs were initiated in 2017. Low-price generics and biosimilar of trastuzumab came into the market in 2020 and 2021, separately. Interrupted time series analysis showed that the DDDs increased significantly after the implementation of NHIC, price negotiation or generic drug replacement.ConclusionThe consumption of anti-HER2 drugs has significantly increased and their DDC has decreased after the implementation of NHIC, price negotiation, or low-price generic drug replacement since 2017. Further efforts are needed to translate the high consumption into clinical benefits.

PIK3CA Mutation is Associated with Poor Response to HER2-Targeted Therapy in Breast Cancer Patients.

Mutations in the PIK3CA gene occur frequently in breast cancer patients. Activating PIK3CA mutations confer resistance to human epidermal growth factor receptor 2 (HER2)-targeted treatments. In this study, we investigated whether PIK3CA mutations were correlated with treatment response or duration in patients with HER2-positive (HER2+) breast cancer. We retrospectively reviewed the clinical information of patients with HER2+ breast cancer who received HER2-targeted therapy for early-stage or metastatic cancers. The pathologic complete response (pCR), progression-free survival (PFS), and overall survival were compared between patients with wild-type PIK3CA (PIK3CAw) and those with mutated PIK3CA (PIK3CAm). Next-generation sequencing was combined with examination of PFS associated with anti-HER2 monoclonal antibody (mAb) treatment. Data from 90 patients with HER2+ breast cancer were analyzed. Overall, 34 (37.8%) patients had pathogenic PIK3CA mutations. The pCR rate of the PIK3CAm group was lower than that of the PIK3CAw group among patients who received neoadjuvant chemotherapy for early-stage cancer. In the metastatic setting, the PIK3CAm group showed a significantly shorter mean PFS (mPFS) with first-line anti-HER2 mAb. The mPFS of second-line T-DM1 was lower in the PIK3CAm group than that in the PIK3CAw group. Sequencing revealed differences in the mutational landscape between PIK3CAm and PIK3CAw tumors. Patients with HER2+ breast cancer with activating PIK3CA mutations had lower pCR rates and shorter PFS with palliative HER2-targeted therapy than those with wild-type PIK3CA. Precise targeted-therapy is needed to improve survival of patients with HER2+/PIK3CAm breast cancer.

1190TiP Pharmacokinetics, efficacy, and safety of patritumab deruxtecan (HER3-DXd) in EGFR inhibitor-resistant, EGFR-mutated (EGFRm) non-small cell lung cancer (NSCLC)

Patients (pts) with advanced EGFRm NSCLC have limited treatment options after progression with an EGFR tyrosine kinase inhibitor (TKI) and platinum-based chemotherapy (PBC). HER3, a member of the human epidermal growth factor receptor family, is expressed across a variety of solid tumors and in most EGFRm NSCLC. HER3 overexpression has been associated with poor clinical outcomes, including metastatic progression and decreased relapse-free survival. HER3-DXd is a novel antibody-drug conjugate composed of a human anti-HER3 monoclonal antibody (patritumab) linked to a topoisomerase I inhibitor payload via a stable tetrapeptide-based, tumor-selective, cleavable linker.

1195TiP HERTHENA-Lung02: A randomized phase III study of patritumab deruxtecan vs platinum-based chemotherapy in locally advanced or metastatic EGFR-mutated NSCLC after progression with a third-generation EGFR TKI

Standard therapies for patients (pts) with epidermal growth factor receptor–mutated (EGFRm) non-small cell lung cancer (NSCLC) that has progressed after treatment with third-generation (3rd-gen) EGFR tyrosine kinase inhibitors (TKIs) offer only a limited benefit. Human epidermal growth factor receptor 3 (HER3) is often expressed in primary NSCLC tumors, and HER3 expression is commonly observed in patients with EGFR mutations. HER3-DXd is a novel antibody-drug conjugate composed of a human anti-HER3 monoclonal antibody (patritumab) linked to a topoisomerase I inhibitor payload via a tetrapeptide-based cleavable linker.

15P The analgesic compound palmitoylethanolamide reduces inflammation in human cardiomyocytes and vascular endothelial cells exposed to doxorubicin and anti-HER2 monoclonal antibody through PPAR-α and NLRP3-related pathways

Palmitoylethanolamide (PEA) is an endogenous fatty acid mediator that is synthetized from membrane phospholipids by N-acyl phosphatidylethanolamine phospholipase D. It is a new analgesic drug with anti-inflammatory effects through the induction of PPAR-related pathways. We aimed to assess whether palmitoylethanolamide co-incubated during doxorubicin and trastuzumab, reduces anticancer drugs-related cardiotoxicity in cellular models.

Development and validation of an ELISA method for quantification of the anti-HER3 antibody HMBD-001 in human serum.

Background: HMBD-001 is an IgG1 humanized monoclonal antibody specifically targeting HER3, a receptor highly expressed on cancer cells in certain tumors. A bioanalytical method was required to quantify HMBD-001 in human serum, with high selectivity and without interference from HER3. Methods and results: A bridging ELISA using an anti-idiotypic monoclonal capture and detection was developed and validated for quantitative measurement of HMBD-001 in human serum. The assay is sensitive, with alower limit of quantification of 250ng/ml, has a broad dynamic range of 250-7000ng/mlHMBD-001, and exhibits excellent precision and overall accuracy. Conclusion: We have developed and validated a sensitive and selective method for measuring HMBD-001 in human serum. This assay is now being used in a clinical trial setting.

93P An AI-driven computational biomarker from H&E slides recovers cases with low levels of HER2 from immunohistochemically HER2-negative breast cancers

Novel anti-HER2 antibody drug conjugates (ADCs) have shown efficacy in breast cancers (BCs) expressing low levels of HER2 (i.e., IHC 1+/2+). A subset of BCs classified as HER2 0 by current IHC methods may express HER2 protein. We sought to define whether BCs expressing HER2 could be accurately detected by deep learning (DL) methods applied to H&E whole slide images (WSIs), using a combination of IHC and HER2 mRNA expression as ‘gold standard’.

Proposal to distinguish HER2-low from HER2-normal breast cancer by in situ hybridisation

Aims‘HER2-low’ breast cancer is an emerging issue as the clinical trials for anti-HER2 antibody–drug conjugates (trastuzumab deruxtecan) are making progress. A reliable method to identify HER2-low cancers is needed. This...

Margetuximab with retifanlimab as first-line therapy in HER2+/PD-L1+ unresectable or metastatic gastroesophageal adenocarcinoma: MAHOGANY cohort A

BackgroundHuman epidermal growth factor receptor 2 (HER2)-positive metastatic gastric and gastroesophageal adenocarcinoma (GEA) is globally treated with chemotherapy plus trastuzumab. Novel therapeutic strategies strive to not only optimize efficacy, but also limit toxicities. In MAHOGANY cohort A, margetuximab, an Fc-engineered, anti-HER2 monoclonal antibody (mAb) was combined with retifanlimab, an anti-programmed cell death protein 1 mAb, in the first-line HER2-positive/programmed death-ligand 1 (PD-L1)-positive GEA.Patients and methodsMAHOGANY cohort A part 1 is a single-arm trial to evaluate margetuximab plus retifanlimab in patients with HER2 immunohistochemistry 3+, PD-L1-positive (combined positive score ≥1%), and non-microsatellite instability-high tumors. Primary objectives for cohort A were safety/tolerability and the confirmed objective response rate (ORR).ResultsAs of 3 August 2021, 43 patients were enrolled and received margetuximab/retifanlimab. Nine grade 3 treatment-related adverse events (TRAEs) were reported in eight (18.6%) patients and eight serious TRAEs in seven (16.3%) patients. There were no grade 4/5 TRAEs. Three patients discontinued margetuximab/retifanlimab because of immune-related adverse events. The ORR by independent assessment was 53% [21/40 (95% confidence interval (CI) 36.1-68.5)], with a median duration of response of 10.3 months (95% CI 4.6-not evaluable); disease control rate was 73% [29/40 (95% CI 56.1-85.4)]. The study sponsor discontinued the study in advance of the planned enrollment when it became apparent that the study design would no longer meet the requirements for drug approval because of recent advances in the treatment of GEA.ConclusionsThe chemotherapy-free regimen of combined margetuximab/retifanlimab as first-line treatment in double biomarker-selected patients demonstrated a favorable toxicity profile compared with historical outcomes using chemotherapy plus trastuzumab. The ORR observed in this study compares favorably versus ORR observed with other chemotherapy-free approaches.

Novel 2,6,9-Trisubstituted Purines as Potent CDK Inhibitors Alleviating Trastuzumab-Resistance of HER2-Positive Breast Cancers.

HER2-positive (HER2+) breast cancer is defined by HER2 oncogene amplification on chromosome 17q12 and accounts for 15–20% population of breast-cancer patients. Therapeutic anti-HER2 antibody such as trastuzumab is used as the first-line therapy for HER2-positive breast cancers. However, more than 50% of the patients respond poorly to trastuzumab, illustrating that novel therapy is warranted to overcome the resistance. We previously reported that in the majority of HER2+ breast-cancer patients, CDK12 is co-amplified on 17q12 and involved in developing tumors and trastuzumab resistance, proposing CDK12 as a potential drug target for HER2+ breast cancers. Here, we designed and synthesized novel 2,6,9-trisubstituted purines as potent CDK12 inhibitors showing strong, equipotent antiproliferative activity against trastuzumab-sensitive HER2+ SK-Br3 cells and trastuzumab-resistant HER2+ HCC1954 cells (GI50 values < 50 nM) both of which express a high level of CDK12. Two potent analogue 30d and 30e at 40, 200 nM greatly downregulated the levels of cyclinK and Pol II p-CTD (Ser2), as well as the expression of CDK12 downstream genes (IRS1 and WNT1) in a dose-dependent manner. We also observed structure-property relationship for a subset of potent analogues, and found that 30e is highly stable in liver microsomes with lack of CYP inhibition. In addition, 30d exhibited a synergy with trastuzumab in the both cells, suggesting that our inhibitors could be applied to alleviate trastuzumab-resistance of HER2+ breast cancers and escalate the efficacy of trastuzumab as well. Our study may provide insight into developing a novel therapy for HER2+ breast cancers.

HER2-Displaying M13 Bacteriophages induce Therapeutic Immunity against Breast Cancer.

Simple SummaryThe high incidence and death rates of breast cancer make the development of new therapies an urgent need. The introduction into the clinic of the anti-HER2 monoclonal antibody trastuzumab considerably improved the overall survival and time-to-disease progression of patients with HER2-positive breast cancer. However, many patients do not benefit from it because of resistance to therapy. Cancer vaccines, by inducing into the patient an anti-cancer specific immunity, might represent an alternative immunotherapeutic approach, but despite promises, so far no anti-HER2 cancer vaccine has been approved for human use. In this study, we propose therapeutic phage-based vaccines, against HER2 and its aggressive isoform Δ16HER2, able to elicit a protective immunity and potentially capable of preventing relapse in HER2-positive breast cancer patients, even in those who develop trastuzumab resistance.The advent of trastuzumab has significantly improved the prognosis of HER2-positive (HER2+) breast cancer patients; nevertheless, drug resistance limits its clinical benefit. Anti-HER2 active immunotherapy represents an attractive alternative strategy, but effective immunization needs to overcome the patient’s immune tolerance against the self-HER2. Phage display technology, taking advantage of phage intrinsic immunogenicity, permits one to generate effective cancer vaccines able to break immune tolerance to self-antigens. In this study, we demonstrate that both preventive and therapeutic vaccination with M13 bacteriophages, displaying the extracellular (EC) and transmembrane (TM) domains of human HER2 or its Δ16HER2 splice variant on their surface (ECTM and Δ16ECTM phages), delayed mammary tumor onset and reduced tumor growth rate and multiplicity in ∆16HER2 transgenic mice, which are tolerant to human ∆16HER2. This antitumor protection correlated with anti-HER2 antibody production. The molecular mechanisms underlying the anticancer effect of vaccine-elicited anti-HER2 antibodies were analyzed in vitro against BT-474 human breast cancer cells, sensitive or resistant to trastuzumab. Immunoglobulins (IgG) purified from immune sera reduced cell viability mainly by impairing ERK phosphorylation and reactivating retinoblastoma protein function in both trastuzumab-sensitive and -resistant BT-474 cells. In conclusion, we demonstrated that phage-based HER2 vaccines impair mammary cancer onset and progression, opening new perspectives for HER2+ breast cancer treatment.

AVB-S6-500, a receptor tyrosine kinase AXL inhibitor, improves the therapeutic efficacy of trastuzumab in uterine serous cancers (278)

<b>Objectives:</b> To determine whether inhibition of <i>GAS6</i>/<i>AXL</i> can improve efficacy to the humanized anti-HER2 monoclonal antibody trastuzumab by decreasing uterine serous cancer cell invasion and cell survival <i>in vitro</i> and tumor burden <i>in vivo</i>. <b>Methods:</b> We treated three uterine serous cancer cell lines (ARK1, ARK2, PUC198) that expressed <i>Her2/neu</i> and <i>AXL</i> receptors with AVB500 (Aravive Biologics, Houston, TX) in combination with Trastuzumab. Clonogenic proliferation assays were performed after three days of treatment, and relative cell viability was calculated using GraphPad Prism. Next, using a Matrigel invasion assay, we examined the invasive capacity of the ARK1 and ARK2 cell lines after 24 hours of treatment with vehicle, AVB500 alone, Trastuzumab alone, or combination Trastuzumab and AVB500. We also performed proximity ligation and IF colocalization assays to show that <i>Her2/neu</i> and <i>AXL</i> receptors form a complex that results in the transphosphorylation and activation of the <i>AXL</i>. We performed <i>in vivo</i> studies using nod-SCID mice injected with 1 x 10⁷ ARK1 and ARK2 cells intraperitoneally, followed by treatment with vehicle control, AVB alone, or Trastuzumab alone or in combination with AVB500 for 35 days and 21 days, respectively. <b>Results:</b> In uterine serous (ARK 2 and PUC 198) cells, there was a significant reduction in cell proliferation when treated with combination Trastuzumab and AVB500 compared to the Trastuzumab-alone group (0.155nm vs 0.202nm, p=0.015; 0.290 vs 0.015, p=0.0044) in ARK 2 and PUC 198 cell lines, respectively. We also observed a reduction in the number of invading tumor cells when cells were treated with combination Trastuzumab and AVB500 versus Trastuzumab alone (3.9 vs 17.7 invading tumor cells/hpf, p=0.0001; 3.2 vs 17.8 invading tumor cells/hpf, p=0.0004) in ARK 1 and ARK 2 cell lines, respectively. Furthermore, the proximity ligation and co-localization assays demonstrated the physical closeness of <i>AXL</i> and <i>HER2</i> receptors in ARK2 cells that could account for the co-regulation of these receptors. Finally, we found that mice treated with Trastuzumab plus AVB -500 developed significantly less tumor burden than mice treated with Trastuzumab alone (0.032 g vs 0.083 g, <i>p</i>= 0.024) in the ARK1 xenograft model and (0.142g vs 0.443 g, <i>p</i>= 0.0015) in the ARK2 xenograft model. <b>Conclusions:</b> The <i>GAS6</i>/<i>AXL</i> inhibitor, AVB-500, potentiated the effect of Trastuzumab to decrease uterine serous cancer cell proliferation and invasion <i>in vitro</i> and tumor burden <i>in vivo</i>. Co-localization of <i>AXL</i> and <i>HER2</i> receptors was seen in both uterine serous cancer cell lines. Our data suggest that the addition of AVB-S6-500 increased the therapeutic efficacy of Trastuzumab therapy in uterine serous cancers. Additional therapeutic and mechanistic experiments are ongoing.

A phase 2, multicenter, open-label study evaluating trastuzumab deruxtecan (T-DXd) for the treatment of select human epidermal growth factor receptor 2 (HER2)-expressing solid tumors (DESTINY-PanTumor02) (296)

<b>Objectives:</b> Human epidermal growth factor receptor 2 (HER2) is an established therapeutic target in both breast and gastric cancer. However, HER2-targeting therapies are not approved beyond these malignancies despite a high prevalence of HER2 expression across cancers of epithelial origin. Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate consisting of an anti-HER2 antibody, a cleavable tetrapeptide-based linker, and a topoisomerase I inhibitor payload. In a cohort of pretreated patients with multiple HER2-expressing tumors, T-DXd demonstrated promising antitumor activity, with an investigator-assessed confirmed objective response rate of 40.9% (9 of 22 patients) and median progression-free survival of 11.1 months (95% CI: 5.4-20.5 months; Tsurutani J, et al. <i>Cancer Discov</i>. 2020;10:688-701). Here we describe the phase II DESTINY-PanTumor02 trial evaluating T-DXd in patients with select HER2-expressing solid tumors. <b>Methods:</b> DESTINY-PanTumor02 (NCT04482309) is an open-label, multi-center, multi-cohort, phase II study evaluating T-DXd for the treatment of patients with select HER2-expressing locally advanced, unresectable, or metastatic tumors. The study will consist of seven cohorts of patients (<i>n</i>≈40 each) with urothelial bladder, biliary tract, cervical, endometrial, ovarian, pancreatic, or rare tumors (tumors excluding those in the other cohorts and breast, gastric, colorectal, and non-small cell lung cancer). Patients are required to have disease progression following ≥1 prior systemic treatment for advanced or metastatic disease or have no satisfactory alternative treatment options. Prior HER2-targeting therapy is allowed. The primary endpoint is investigator-assessed confirmed objective response rate per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Secondary endpoints include duration of response, disease control rate, progression-free survival (all per investigator assessment according to RECIST 1.1), overall survival, safety, pharmacokinetics, and immunogenicity. Previously presented at the ESMO Congress 2021, FPN:1869 TiP, Meric-Bernstam, et al. - Reused with permission.

In Vivo and In Vitro Efficacy of Enhertu in Uterine Serous Carcinoma (047)

Objectives: Uterine serous carcinoma (USC) is an aggressive subtype of epithelial endometrial cancer, comprising approximately 40% of endometrial cancer-related deaths. HER2 overexpression is detected in about 35% of patients with USC. Enhertu is a novel humanized monoclonal anti-HER2 antibody (trastuzumab) linked to the topoisomerase I inhibitor payload deruxtecan by a cleavable linker. Enhertu is FDA-approved for HER2-expressing metastatic breast and gastric cancers; however, its efficacy has not been tested in endometrial cancer. The objective of this study was to study the in vitro and in vivo efficacy of Enhertu in USC. Methods: HER2 expression was analyzed with flow cytometry in primary USC cell lines: ARK2, ARK4, ARK7, and ARK20. Cell lines were treated with 0.05, 0.010, 0.025, 0.05, 0.2 μg/ml of Enhertu or Control antibody-drug conjugate (Control ADC). The inhibitory concentration 50 (IC50) was assessed by counting the viable cells using a flow cytometer. Apoptosis and necrosis were assessed with Annexin V and propidium iodide (PI) staining. GFP-expressing ARK4 (ARK4-GFP) cells were co-cultured with ARK2 cells for the bystander effect assay. For in vivo experiments, eight million ARK2 cells were injected subcutaneously into SCID mice. Animals were randomized to intravenous injection of PBS (n=5), control ADC (4 mg/kg, n=6) or Enhertu (4 mg/kg, n=5) treatment. Kruskal Wallis, Friedman, and Log Rank tests were used for statistical analysis. Graphical Abstract View Large Image Figure Viewer Download Hi-res image Graphical Abstract View Large Image Figure Viewer Download Hi-res image Conclusions: Enhertu showed significant preclinical efficacy against HER2 overexpressing uterine serous carcinoma cell lines. Further clinical trials in USC are warranted. Objectives: Uterine serous carcinoma (USC) is an aggressive subtype of epithelial endometrial cancer, comprising approximately 40% of endometrial cancer-related deaths. HER2 overexpression is detected in about 35% of patients with USC. Enhertu is a novel humanized monoclonal anti-HER2 antibody (trastuzumab) linked to the topoisomerase I inhibitor payload deruxtecan by a cleavable linker. Enhertu is FDA-approved for HER2-expressing metastatic breast and gastric cancers; however, its efficacy has not been tested in endometrial cancer. The objective of this study was to study the in vitro and in vivo efficacy of Enhertu in USC. Methods: HER2 expression was analyzed with flow cytometry in primary USC cell lines: ARK2, ARK4, ARK7, and ARK20. Cell lines were treated with 0.05, 0.010, 0.025, 0.05, 0.2 μg/ml of Enhertu or Control antibody-drug conjugate (Control ADC). The inhibitory concentration 50 (IC50) was assessed by counting the viable cells using a flow cytometer. Apoptosis and necrosis were assessed with Annexin V and propidium iodide (PI) staining. GFP-expressing ARK4 (ARK4-GFP) cells were co-cultured with ARK2 cells for the bystander effect assay. For in vivo experiments, eight million ARK2 cells were injected subcutaneously into SCID mice. Animals were randomized to intravenous injection of PBS (n=5), control ADC (4 mg/kg, n=6) or Enhertu (4 mg/kg, n=5) treatment. Kruskal Wallis, Friedman, and Log Rank tests were used for statistical analysis. Conclusions: Enhertu showed significant preclinical efficacy against HER2 overexpressing uterine serous carcinoma cell lines. Further clinical trials in USC are warranted.

AlGaN/GaN HEMT Based Biosensor for Detection of the HER2 Antigen Spiked in Human Serum

This work reports the development of a gallium nitride-based high electronic mobility transistor (GaN HEMT)-based biosensor to detect human epidermal growth factor receptor-2 (HER2) antigen in spiked human serum. The platform devices have been fabricated with a source to drain distance, gate length, and unit gate width of 25, 3, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100 ~\mu \text{m}$ </tex-math></inline-formula> , respectively. The cysteine methyl ester (CME)-based chemistry has been utilized to immobilize the antiHER2 antibody on the sensing region of the sensor. The formation of the CME layer was confirmed through Raman spectroscopy, which shows a peak around a wavelength of 262 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> . The antibody immobilization on the gold surface has been confirmed through enzyme-linked immunosorbent assay (ELISA). The sensor has been electrically characterized before and after each step of the functionalization process. The sensor shows a significant change in the drain current of 0.95 and 1.7 mA at a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{{\mathrm {ds}}} $ </tex-math></inline-formula> of +5 V for 50- and 200-ng/ml concentration of HER2 in spiked human serum. A minor change in the drain current of the sensor, when tested with a nonspecific antigen, suggested the high specificity of the sensor for HER2. The sensor has been tested for a broad range concentration of HER2 antigen from 0.7 pg/ml to 200 ng/ml.

IFI16-dependent STING signaling is a crucial regulator of anti-HER2 immune response in HER2+ breast cancer

Relapse to anti-HER2 monoclonal antibody (mAb) therapies, such as trastuzumab in HER2+ breast cancer (BC), is associated with residual disease progression due to resistance to therapy. Here, we identify interferon-γ inducible protein 16 (IFI16)-dependent STING signaling as a significant determinant of trastuzumab responses in HER2+ BC. We show that down-regulation of immune-regulated genes (IRG) is specifically associated with poor survival of HER2+, but not other BC subtypes. Among IRG, IFI16 is identified as a direct target of EZH2, the underexpression of which leads to deficient STING activation and downstream CXCL10/11 expression in response to trastuzumab treatment. Dual inhibition of EZH2 and histone deacetylase (HDAC) significantly activates IFI16-dependent immune responses to trastuzumab. Notably, a combination of a novel histone methylation inhibitor with an HDAC inhibitor induces complete tumor eradication and long-term T cell memory in a HER2+ BC mouse model. Our findings demonstrate an epigenetic regulatory mechanism suppressing the expression of the IFI16-CXCL10/11 signaling pathway that provides a survival advantage to HER2+ BC to confer resistance to trastuzumab treatment.