EGFR Monoclonal Antibody Research Articles

Afatinib and Necitumumab in EGFR-Mutant Non-Small Cell Lung Cancer with Acquired Resistance to EGFR Tyrosine Kinase Inhibitors

IntroductionAlthough tyrosine kinase inhibitors (TKIs) are effective against non-small cell lung cancer (NSCLC) harboring sensitizing epidermal growth factor receptor (EGFR) gene mutations, acquired resistance is inevitable. Preclinical studies suggest combining EGFR TKI and monoclonal antibody therapies may have activity in EGFR-mutated NSCLC that has progressed on TKI therapy alone. Therefore, we prospectively evaluated afatinib plus necitumumab in patients with EGFR-mutated NSCLC. MethodsThis was a phase I dose-escalation, dose-expansion trial assessing the safety and efficacy of afatinib plus necitumumab. Patients had advanced or metastatic EGFR-mutated NSCLC with progression after: (1) first-generation TKI if T790M-negative; (2) subsequent line third-generation TKI if T790M-positive; or (3) third-generation TKI in the first-line setting. Dose-escalation followed a 3+3 design. The primary endpoint of dose-expansion was objective response rate (ORR). ResultsA total of 22 patients with EGFR-mutated NSCLC were enrolled. The maximum tolerated dose (MTD) was afatinib 40 mg oral daily plus necitumumab 600 mg intravenous on days 1 and 15 every 28 days. There were no Grade 4-5 adverse events observed, and seven patients (32%) experienced Grade 3 treatment-related adverse events (3 rash; 1 each oral mucositis, diarrhea, headache, and ventricular arrhythmia and tachycardia). In the entire cohort, there were no responses observed, the median progression-free survival (PFS) was 1.8 months, and the disease control rate (DCR) was 36% but varied between subgroups. ConclusionsAfatinib plus necitumumab was safe but showed limited activity in patients with EGFR-mutated NSCLC. Biomarker studies may identify patient subgroups that are more likely to benefit.

MO40-3 Impact of acquired RAS, BRAF and PIK3CA mutation at 8 weeks on the efficacy of anti- EGFR monoclonal antibodies in mCRC

MO40-3 Impact of acquired RAS, BRAF and PIK3CA mutation at 8 weeks on the efficacy of anti- EGFR monoclonal antibodies in mCRC

EGFR-directed antibodies promote HER2 ADC internalization and efficacy.

Trastuzumab deruxtecan (T-DXd) is a human epidermal growth factor receptor 2 (HER2)-targeting antibody drug conjugate that has remarkable activity in HER2-positive cancers. However, the degree of benefit of T-DXd is not uniform among solid tumors even with high levels of HER2. Despite high HER2 expression, the HER2/T-DXd complex may not always undergo internalization and payload release dependent on the receptor's conformation and context. We hypothesize that epidermal growth factor receptor (EGFR), a dimerization partner of HER2, can modulate HER2 trafficking through endocytic pathways and affect T-DXd uptake. We demonstrate that elevated EGFR expression levels can promote EGFR/HER2 heterodimer formation and suppress T-DXd internalization and efficacy. Knockdown of EGFR expression or pharmacologic stimulation of EGFR endocytosis with EGFR monoclonal antibodies restores T-DXd trafficking and antitumor activity in EGFR-overexpressing cancers invivo. Our results reveal EGFR overexpression to be a potential mechanism of resistance to T-DXd, which can be overcome by combination therapy strategies targeting EGFR.

Photoimmunotheranostics of epithelioid sarcoma by targeting CD44 or EGFR

Epithelioid sarcoma (ES) is a rare soft tissue neoplasm with high recurrence rates. Wide surgical resection remains the only potential curative treatment. ES presents most commonly on the fingers, hands and forearm, making light-based cancer cell-targeted therapies such as near-infrared photoimmunotherapy (NIR-PIT) that is target-specific, but with limited penetration depth, suitable for ES treatment. We established that CD44 and EGFR were overexpressed in ES patient samples and in the VA-ES-BJ human ES cell line. NIR-PIT of VA-ES-BJ cells using antibody photosensitizer conjugates, prepared by conjugating a CD44 or EGFR monoclonal antibody to the photosensitizer IR700, confirmed that NIR-PIT with both conjugates resulted in cell death. Neither treatment with NIR light alone nor treatment with the conjugates but without NIR light were effective. CD44-IR700-PIT resulted in greater cell death than EGFR-IR700-PIT, consistent with the increased expression of CD44 by VA-ES-BJ cells. In tumors, EGFR-IR700 exhibited a higher tumor-to-normal ratio, as determined by in vivo fluorescence imaging, and a higher anti-tumor growth effect, compared to CD44-IR700. No antitumor effect of the EGFR antibody or the photosensitizer conjugate alone was observed in vivo. Our data support evaluating the use of EGFR-IR700-PIT in the management of ES for detecting and eliminating ES cells in surgical margins, and in the treatment of superficial recurrent tumors.

Sequential RAS mutations evaluation in cell-free DNA of patients with tissue RAS wild-type metastatic colorectal cancer: the PERSEIDA (Cohort 2) study

PurposeRAS (KRAS/NRAS) mutational status on a tumor biopsy is mandatory to guide the best treatment in metastatic colorectal cancer (mCRC). Determining the RAS mutational status by tumor-tissue biopsy is essential in guiding the optimal treatment decision for mCRC. RAS mutations are negative predictive factors for the use of EGFR monoclonal antibodies. Cell-free DNA (cfDNA) analysis enables minimally invasive monitoring of tumor evolution.Methods/patientsPERSEIDA was an observational, prospective study assessing cfDNA RAS, BRAF and EGFR mutations (using Idylla™) in first-line mCRC, RAS wild-type (baseline tumor-tissue biopsy) patients (cohort 2). Plasma samples were collected before first-line treatment, after 20 ± 2 weeks, and at disease progression.Results117 patients were included (103 received panitumumab + chemotherapy as first-line treatment). At baseline, 7 (6.8%) patients had RAS mutations, 4 (3.9%) BRAF mutations and no EGFR mutations were detected (cfDNA, panitumumab + chemotherapy subpopulation [panitumumab + Ch]). The baseline RAS mutational status concordance between tissue and liquid biopsies was 94.0% (93.2%, panitumumab + Ch). At 20 weeks, only one patient in the study (included in the panitumumab + Ch) had an emerging cfDNA RAS mutation. No emerging BRAF or EGFR mutations were reported. At disease progression, 6 patients had emergent mutations not present at baseline (RAS conversion rate: 13.3% [6/45]; 15.0% [6/40], panitumumab + Ch).ConclusionsThe concordance rate between liquid and solid biopsies at baseline was very high, as previously reported, while our results suggest a considerable emergence of RAS mutations during disease progression. Thus, the dynamics of the genomic landscape in ctDNA may provide relevant information for the management of mCRC patients.

Preparation of a Zirconium-89 Labeled Clickable DOTA Complex and Its Antibody Conjugate.

Desferrioxamine B (DFO) is the clinical standard chelator for preparing zirconium-89 labeled antibodies. In the current study, the stabilities of a zirconium-89 labeled panitumumab (PAN; Vectibix®) with three different chelators (DFO, DFO*, and DOTA) were compared. PAN is an anti-HER1/EGFR monoclonal antibody approved by the FDA for the treatment of HER1-expressing colorectal cancers and was used as the model antibody for this study. DFO/DFO* conjugates of PAN were directly radiolabeled with zirconium-89 at room temperature to produce [89Zr]Zr-DFO/DFO*-PAN conjugates following a well-established procedure. A zirconium-89 labeled DOTA-PAN conjugate was prepared by an indirect radiolabeling method. A cyclooctyne-linked DOTA chelator (BCN-DOTA-GA) was first radiolabeled with zirconium-89 at 90 °C under a two-step basic pH adjustment method followed by conjugation with PAN-tetrazene at 37 °C to produce a labeled conjugate, BCN-[89Zr]Zr-DOTA-GA-PAN. High reproducibility of the radiolabeling was observed via this two-step basic pH adjustment. The overall radiochemical yield was 40-50% (n = 12, decay uncorrected) with a radiochemical purity of >95% in 2 h synthesis time. All three conjugates were stable in whole human serum for up to 7 days at 37 °C. The kinetic inertness of the conjugates was assessed against the EDTA challenge. BCN-[89Zr]Zr-DOTA-GA-PAN exhibited excellent inertness followed by [89Zr]Zr-DFO*-PAN. [89Zr]Zr-DFO-PAN displayed the lowest level of inertness.

Abstract LB056: IBI334, a novel ADCC-enhanced B7-H3/EGFR bispecific antibody, demonstrated potent pre-clinical efficacy in solid tumors

Abstract Many solid tumors, such as colorectal cancer (CRC) and lung cancer, are dependent on epidermal growth factor receptor (EGFR) pathway for tumor growth. Antibodies that inhibit EGFR signaling, such as Cetuximab, show clinical efficacy but are associated with on-target toxicities that potentially limit the drug efficacy. To enhance the EGFR signaling inhibition and reduce on-target toxicities, we performed bioinformatics analysis for EGFR/TAA co-expression. We found that B7-H3, a member of the B7 family of immune checkpoint proteins, is broadly expressed in many solid tumors and their expression correlates with EGFR expression in multiple cancers, including lung cancer, head and neck cancer, pancreatic cancer and esophageal cancer. Using Innovent’s proprietary Innobody platform, we developed a bispecific antibody, IBI334, against B7-H3 and EGFR. IBI334 has an EGFR arm for signal blockage and is coupled with a fine-tuned B7-H3 arm with optimal affinity and binding domain. With the aid of B7-H3, IBI334 showed enhanced EGFR signal inhibition than Zalutumumab (EGFR mAb) and Amivantamab (c-met/EGFR bsAb). In addition, IBI334 is afucosylated to enhance its antibody-mediated cell cytotoxicity (ADCC) effects as compared to wild type antibody. IBI334 showed significantly better in vivo efficacy than Amivantamab in NCI-H358 (bronchioalveolar carcinoma with KRAS-G12C mutation), NCI-H292 (lymph node metastasis of a pulmonary mucoepidermoid carcinoma), SK-MES1 (lung cancer) and SK-MES1-LTC (lung cancer with EGFR L858R, T790M and C797S mutations) xenograft models and comparable efficacy in NCI-H322-EGFRexon20ins (lung cancer) model. Cetuximab, an EGFR monoclonal antibody, had high on-target toxicity with 50% early mortalities in cynomolgus monkeys at 120/75 mg/kg/week. With the careful design of B7-H3/EGFR bispecific antibody, IBI334 ameliorated the on-target toxicities and showed only slight hardening of the skin at the injection site at 120 mg/kg/week. As a result, IBI334 has a large therapeutic window of >200 folds. In conclusion, IBI334 is a potent B7-H3/EGFR bispecific antibody with broad application in many EGFR-driven solid tumors. The large therapeutic window enables safe and effective cancer treatment at high exposure levels. Citation Format: Jian Guan, Shuaixiang Zhou, Weiwei Wu, Tianyu Zhu, Lei Cao, Ming Wu, Ninghuan Li, Fenggen Fu, Zhengguan Liao, Shuming Lin, Zeyu Liu, Mengjia Zhu, Nana Luo, Ying Zhang, Tiong Sun Chia, Bingliang Chen, Kaijie He. IBI334, a novel ADCC-enhanced B7-H3/EGFR bispecific antibody, demonstrated potent pre-clinical efficacy in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB056.

Abstract 4553: DXC004A, a novel EGFR antibody-tubulysin analog conjugate demonstrated potential to broaden therapeutic opportunities for non-small cell lung cancer

Abstract EGFR is a member of the epidermal growth factor receptor (HER) family, and the over-expression of EGFR plays an important role in the growth and progression of various tumors, including non-small cell lung cancer. Monoclonal EGFR antibodies, such as cetuximab and panitumumab, have proven efficacy in various types of cancer. However, treatment with the anti-EGFR agents can be associated with toxicities of the skin, nails, hair, and eyes. Nimotuzumab (Nimo) is the first humanized monoclonal antibody targeting EGFR and has been granted approval for use in squamous cell carcinoma of head and neck (SCCHN), glioma and nasopharyngeal cancer in different countries. In contrast to cetuximab, Nimotuzumab is distinguished by achieving higher or similar complete remission rate (CRR) or overall remission rate (ORR) of the primary tumor in clinical applications but much less toxicity, resulting in a better safety profile, which has been attributed to its about 10-fold lower affinity. Paclitaxel combined with cisplatin is the first-line chemotherapy regimen for non-small cell lung cancer. A phase 2 clinical trial has confirmed that Nimotuzumab combined with concurrent chemoradiation therapy (radiation concurrent with docetaxel and cisplatin, CCRT) was well tolerated for locally advanced squamous cell lung cancer. However, the combination strategy of Nimo-CCRT has only demonstrated similar OS and PFS to those in the CCRT group. DXC004A is an ADC drug targeting EGFR, in which a Nimotuzumab derivative and a Tubulysin B analog is conjugated by a functional linker. DXC004A is in phase I clinical trial and has demonstrated clinical activity in advanced non-small cell lung cancers and good tolerability. In vitro and in vivo results had confirmed that DXC004A monotherapy had better anti-tumor activity than the combination of Nimotuzumab and Tubulysin analog in HCC827 cell lines with high EGFR expression. Meanwhile, a single injection of low-dose DXC004 (2.5 mg/kg) in HCC827 xenograft model showed very good durable anti-tumor effect. Moreover, the combination of DXC004A with Cisplatin exhibited significantly better activities than that of Nimo-CCRT combination, DXC004A or cisplatin alone, in vitro and in vivo, which might solve the predicament of poor efficacy of Nimo-CCRT combination therapy. This synergy results suggested that DXC004A plus cisplatin would possibly be a new adjuvant therapy for non-small cell lung cancer in further clinical studies. Citation Format: Xiaobo Cai, Min Cao, Huihui Guo, Qingliang Yang, Yongxiang Chen, Xiangfei Kong, Yong Du, Zhicang Ye, Zhixiang Guo, Lingli Zhang, Lu Bai, Junxiang Jia, Yunxia Zheng, Wei Zheng, Jun Zheng, Wenjun Li, Yuanyuan Huang, Zhongliang Fan, Binbin Chen, Meng Dai, Robert Y. Zhao. DXC004A, a novel EGFR antibody-tubulysin analog conjugate demonstrated potential to broaden therapeutic opportunities for non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4553.

Fluoropyrimidine type, patient age, tumour sidedness and mutation status as determinants of benefit in patients with metastatic colorectal cancer treated with EGFR monoclonal antibodies: individual patient data pooled analysis of randomised trials from the ARCAD database

BackgroundKRAS mutations in metastatic colorectal cancer (mCRC) are used as predictive biomarkers to select therapy with EGFR monoclonal antibodies (mAbs). Other factors may be significant determinants of benefit.MethodsIndividual patient data from randomised trials with a head-to-head comparison between EGFR mAb versus no EGFR mAb (chemotherapy alone or best supportive care) in mCRC, across all lines of therapy, were pooled. Overall survival (OS) and progression-free survival (PFS) were compared between groups. Treatment effects within the predefined KRAS biomarker subsets were estimated by adjusted hazard ratio (HRadj) and 95% confidence interval (CI). EGFR mAb efficacy was measured within the KRAS wild-type subgroup according to BRAF and NRAS mutation status. In both KRAS wild-type and mutant subgroups, additional factors that could impact EGFR mAb efficacy were explored including the type of chemotherapy, line of therapy, age, sex, tumour sidedness and site of metastasis.Results5675 patients from 8 studies were included, all with known mCRC KRAS mutation status. OS (HRadj 0.90, 95% CI 0.84–0.98, p = 0.01) and PFS benefit (HRadj 0.73, 95% CI 0.68–0.79, p < 0.001) from EGFR mAbs was observed in the KRAS wild-type group. PFS benefit was seen in patients treated with fluorouracil (HRadj 0.75, 95% CI 0.68–0.82) but not with capecitabine-containing regimens (HRadj 1.04, 95% CI 0.86–1.26) (pinteraction = 0.002). Sidedness also interacted with EGFR mAb efficacy, with survival benefit restricted to left-sided disease (pinteraction = 0.038). PFS benefits differed according to age, with benefits greater in those under 70 (pinteraction = 0.001). The survival benefit was not demonstrated in those patients with mutations found in the KRAS, NRAS or BRAF genes. The presence of liver metastases interacted with EGFR mAb efficacy in patients with KRAS mutant mCRC (pinteraction = 0.004).ConclusionThe benefit provided by EGFR mAbs in KRAS WT mCRC is associated with left-sided primary tumour location, younger patient age and absence of NRAS or BRAF mutations. Survival benefit is observed with fluorouracil but not capecitabine. Exploratory results support further research in KRAS mutant mCRC without liver metastases.

Tumor genomics and sidedness to predict outcomes in metastatic colorectal cancer (mCRC).

207 Background: Tumor sidedness is a prognostic factor and predictive parameter for EGFR monoclonal antibody (mAb) treatment in mCRC. Sidedness is believed to be a surrogate for genomic differences. This study aimed to evaluate genomics vs. tumor sidedness in anticipating outcomes in mCRC. Methods: We included patients (pts) with microsatellite stable mCRC tested by Foundation Medicine tissue comprehensive genomic profiling assay. Patient data was obtained by the US-based de-identified Flatiron Health-Foundation Medicine real-world clinico-genomic database (FH-FMI CGDB), originating from approximately 280 US cancer clinics (1/2011–3/2023). Genomic alterations (GA) in 324 genes were compared between right and left side tumors using Fisher’s exact test, adjusted for multiple comparisons. Real-world progression-free survival (rwPFS) and overall survival (rwOS) were compared by Cox proportional hazard models adjusted for prognostic features in pts receiving 1st line chemotherapy (chemo) + EGFR mAb or bevacizumab (bev). Multivariable analyses including prognostic features, sidedness and GA were performed. Comparisons of the explanatory power of genomics vs. sidedness were performed by the likelihood ratio test (LRT). Results: 3845mCRC pts (2584 left and 1261 right) were included. GA in APC, TP53, ARID1A, and FBXW7 were more prevalent in left side, while GA in BRAF, KRAS, AMER1A, PIK3CA, RNF43, BCOR, PTEN, SMAD4, MAP2K1, and BCOR in right side. 2109 pts received chemo + EGFR mAb or bev. Multivariable analyses identified BRAF, KRAS, MAP2K1, and APC as independently associated with outcomes. Pts were classified as having GA in RAS pathway (RASalt: KRAS/NRAS, BRAF, or MAP2K1), APC (APCalt), both RAS pathway and APC (APC/RASalt), and none. RASalt group had less favorable outcomes while APCalt group had more favorable outcomes, regardless of treatment received and sidedness. LRT indicated that when genomics was added to the sidedness evaluation, there was an improvement in outcome prediction (p&lt;0.001), but not when sidedness was added to genomics. Conclusions: Tumor genomics better explains differences in outcomes than sidedness in 1st line treatment in mCRC. [Table: see text]

FOXP3 expression in esophageal squamous cell carcinoma : Implications for cetuximab sensitivity and therapeutic strategies.

Investigating the impact of FOXP3 (transcription factor forkhead box P3) expression on the biological behavior of esophageal squamous cell carcinoma (ESCC) and its influence on the sensitivity of ESCC cells towards cetuximab-targeted (an EGFR monoclonal antibody inhibitor) therapy. Aspecifically designed recombinant FOXP3 shRNA plasmid was synthesized to target the human FOXP3 gene, and the plasmid was transfected into TE12 cells using aliposome method. Multiple assays were conducted to evaluate the effect of FOXP3 expression on ESCC cells and their response to cetuximab treatment. Proliferation activity and cetuximab sensitivity of ESCC cells were measured using the CCK‑8 assay. The invasion ability of cells was assessed using an in vitro invasion assay. Furthermore, the efficacy of cetuximab in treating ESCC was analyzed using atumorigenesis assay in nude mice. Silencing the FOXP3 gene in the TE12 cell line (shFOXP3 group) resulted in asignificant reduction in FOXP3 mRNA and protein expression (p = 0.013). The shFOXP3 group exhibited slowed cell growth (p = 0.035), decreased invasion rate (p = 0.031), and increased sensitivity to cetuximab treatment (p = 0.039) compared to the control group (shNC group). In the in vivo tumorigenesis assay, the shFOXP3 group demonstrated asignificant reduction in tumor volume and lung metastasis rate following cetuximab treatment (p = 0.028 and 0.007, respectively). High FOXP3 expression promotes the proliferation and migration of ESCC cells, while negatively affecting their sensitivity to cetuximab-targeted therapy. Consequently, targeting FOXP3 shows potential therapeutic implications for enhancing the effectiveness of cetuximab treatment in ESCC patients.

EGFR Suppression Inhibits the Sphere Formation of MCF7 Cells Overexpressing EGFR.

The epidermal growth factor receptor (EGFR) is an oncogenic tyrosine kinase that is involved in tumor initiation and progression, making EGFR inhibitors and monoclonal antibodies to this receptor essential for anti-tumor therapy. We have previously shown that EGFR transgene expression in the human breast adenocarcinoma cell line MCF7 (MCF7-EGFR) stimulates the 3D spheroid-like growth. The primary focus of our present work was to investigate whether EGFR inhibition could affect the assembly of spheroids or lead to the destruction of pre-existing spheroids. We compared the effects of anti-EGFR siRNA, the anti-EGFR monoclonal antibody cetuximab, and the tyrosine kinase inhibitor AG1478 on dissociated and spheroid MCF7-EGFR cells. MCF7-EGFR cells were found to have a 2.5-fold higher sensitivity towards the cytotoxic effects of cetuximab and AG1478 compared with the parental MCF7 cell line. The suppression of EGFR mRNA with siRNA was found to reduce the sphere formation, whereas treating the pre-existing spheroids had no such effect. Treatment of dissociated spheroids with cetuximab and AG1478 was also found to inhibit the MCF7-EGFR sphere formation. We suggest that EGFR expression is important, at least, during the spheroid formation stage. The transition of a MCF7wt adherent cell culture to MCF7-EGFR spheroids was accompanied by a considerable increase in N-cadherin adhesion proteins. The level of N-cadherin decreased when MCF7-EGFR cells were treated with siRNA and cetuximab. Thus, we have demonstrated that N-cadherin is involved in the EGFR-dependent formation of MCF7-EGFR spheroids. Accordingly, MCF7-EGFR spheroids can be considered a suitable model for studying aggressive hormone-positive breast tumors.

EGFR inhibitor erlotinib plus monoclonal antibody versus erlotinib alone for first-line treatment of advanced non-small cell lung carcinoma: A systematic review and meta-analysis.

Immuno-combination therapy is emerging as an effective treatment for advanced non-small cell lung carcinoma (NSCLC). However, compared to monotherapy, such as monoclonal antibodies or kinase inhibitors, whether combination therapy can enhance antitumor efficacy or alleviate side effects remains unclear. A systematic literature search was undertaken using the PubMed, Embase, Web of Science and Cochrane Central Register of Controlled Trials databases to identify eligible studies concentrating on treatment with erlotinib or erlotinib plus monoclonal antibodies in NSCLC patients published between January 2017 and June 2022. The primary outcomes included progression-free survival (PFS), overall survival (OS), response rate (RR) and treatment-related adverse events (AEs). Seven independent randomized, controlled clinical trials including 1513 patients were obtained for the final analysis. Erlotinib plus monoclonal antibodies was significantly associated with the improvement of PFS (hazards ratio [HR], 0.60; 95% CI 0.53-0.69; z=7.59, P<0.01) and with moderate performance regarding OS (HR, 0.81; 95% CI 0.58-1.13; z=1.23, P=0.22) and RR (odds ratio [OR], 1.25; 95% CI 0.98-1.59; z=1.80, P=0.07), irrespective of EGFR mutation status. In the safety evaluation, erlotinib plus monoclonal antibodies had a markedly higher occurrence of adverse events (AEs) of Clavien grade 3 or higher (OR, 3.32; 95% CI 2.66-4.15; z=10.64, P<0.01). Compared with erlotinib alone, combination therapy (erlotinib plus monoclonal antibodies) was associated with significantly improved PFS in NSCLC therapy, accompanied by increased treatment-related AEs. Our systematic review protocol was registered in the PROSPERO international register of systematic reviews (CRD42022347667).

Abstract IA07: Molecular characterization of acquired resistance to KRASG12C-EGFR inhibition in colorectal cancer

Abstract Until recently, efforts to pharmacologically target KRAS have been unsuccessful due to its small binding pocket, high affinity for GTP, and redundant mechanisms of posttranslational processing. The development of allele specific KRAS G12C inhibitors that trap KRAS in the inactive, GDP-bound, state led to a paradigm change and clinical responses in 30% of non-small cell lung cancer (NSCLC) patients harboring KRAS G12C mutations. KRAS G12C inhibitors, such as sotorasib and adagrasib, have rapidly moved through clinical development and are poised to transform care of patients with KRAS G12C mutant cancers, in particular NSCLC. However, these agents are not as effective in colorectal cancers (CRC) with KRAS G12C mutation. We have previously shown that the activity of these drugs in KRAS G12C CRC is limited because activation of epidermal growth factor receptor (EGFR) reactivates ERK signaling therefore combinatorial KRAS G12C and EGFR inhibition more effectively targets KRAS G12C CRC. Early trial data provide clinical support for this observation as anti EGFR monoclonal antibodies combined with sotorasib or adagrasib double the overall response to single agents in KRAS G12C mutant CRC patients. Based on these data, these KRAS G12C and EGFR antibody combination treatments are being evaluated in registrational, phase 3 trials. Nonetheless, patients treated with these agents, alone or in combination, eventually acquire secondary resistance. Several studies have characterized resistance to KRAS G12C monotherapy, in this work, we sought to determine the mechanisms of acquired resistance to concomitant KRAS and EGFR inhibition in CRC. In cell lines, patient-derived xenograft, and patient samples, a heterogeneous pattern of putative resistance alterations expected primarily to prevent inhibition of ERK signaling by drug can be detected at progression. Serial analysis of patient blood samples during treatment demonstrates that most of these alterations are detected at a low frequency that does not increase substantially and sometimes disappears over time, with the exception of KRAS G12C amplification which rises in step with tumor marker levels and clinical progression. Here we show that a CRC cell line that acquired resistance to sotorasib-cetuximab combination through KRAS G12C amplification undergoes oncogene-induced senescence upon drug withdrawal. Senescence markers were detected in a tissue biopsy from a patient at relapse after treatment stop, and amplified KRAS G12C signal in circulating DNA from relapsed patients rapidly recedes after treatment interruption. These data indicate that while most resistance-associated alterations to KRAS-EGFR coinhibition remain subclonal, affecting a small population of cells, KRAS G12C amplification is a recurrent resistance mechanism that drives a higher portion of resistance over time and provides a potential therapeutic vulnerability, whereby therapies that target the senescence response at drug withdrawal may overcome resistance to KRAS G12C-EGFR inhibition. Citation Format: Sandra Misale. Molecular characterization of acquired resistance to KRASG12C-EGFR inhibition in colorectal cancer [abstract]. In: Proceedings of the AACR Special Conference: Targeting RAS; 2023 Mar 5-8; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Res 2023;21(5_Suppl):Abstract nr IA07.

Current State and Future Directions of EGFR-Directed Therapy in Head and Neck Cancer.

Epidermal growth factor receptor (EGFR) is commonly overexpressed in many head and neck squamous cell carcinomas (HNSCC). With the success of EGFR inhibition in other cancer types, there was optimism for efficacy in HNSCC. Unfortunately, the clinical outcomes of EGFR-directed therapy have not provided overwhelming benefit. In the curative-intent setting, cisplatin has proven superior over cetuximab, an EGFR monoclonal antibody, in multiple large trials, and cisplatin should continue to be the treatment of choice when administered with definitive or adjuvant radiation. For cisplatin-ineligible patients, we prefer carboplatin-based treatment over cetuximab. We reserve cetuximab for a small group of patients who are eligible for radiation and systemic treatment but have contraindications to any platinum therapy. The role of EGFR inhibitors in the recurrent/metastatic setting is more robust. Although supplanted by immunotherapy as front-line treatment, cetuximab remains a meaningful second-line option for patients who have progressed on immune checkpoint inhibitors. Overall, EGFR-directed therapies have been of modest value in the treatment of both locally advanced and metastatic HNSCC. The future of EGFR-directed therapies will likely develop from exploring combination therapies, especially with immunotherapy. Early evidence suggests synergistic effects allowing for a more robust immune response, which holds promise for novel regimens in the treatment of HNSCC.

Abstract 5135: Standardized off-the-shelf engineered NK cell therapy with improved ADCC properties to treat malignancies

Abstract In the treatment of solid tumors, chimeric antigen receptor(CAR)-engineered NK (CAR-NK) cells have distinct advantages over CAR-T cells, such as a lack graft-versus-host disease in allogenic setting to make “off the shelf” medicine; much safer because they are less likely to cause cytokine storms; and NK cells have their own activated receptors that recognize tumor surface antigens and thus have a natural ability to kill a wide range of tumors. In addition, NK cells are the main performers of antibody-dependent cell-mediated cytotoxicity (ADCC), which binds to the Fc-terminus of antibodies through their surface Fc receptor CD16A, thereby killing antibody-targeted tumor cells. Enhancing the ADCC action of NK cells themselves enhances the therapeutic efficacy of monoclonal antibodies targeting tumor surface antigens and is therefore of great importance in the treatment of tumors, especially solid tumors. We screened two optimal structures among nine different Fc chimeric receptors, and NK cells overexpressing these two receptors killed K562 and Daudi six times more intensely than normal NK cells when combined with rituximab, while the killing ability was comparable to that of normal NK without rituximab, indicating that NK cells expressing chimeric Fc receptors have stronger ADCC effects. Moreover, these NK cells can kill target cells in multiple rounds. In vivo experiments in mice demonstrated that NK cells expressing chimeric Fc receptors in combination with EGFR monoclonal antibodies had a stronger inhibitory effect on tumor growth than monoclonal antibodies or NK cells alone. Here we provide a novel broad “off the shelf” NK cells that can significantly enhance the killing ability of hematological and solid tumors in combination with different monoclonal antibodies. Citation Format: Yanan Lin, Shengbang Zhang, Jie Ran, Can Song, Shengcang Zhu, Hui Shi, Ping Guo, Shengjiang Tan, Yuchun Gu, Lida Wu. Standardized off-the-shelf engineered NK cell therapy with improved ADCC properties to treat malignancies. [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 5135.

Genomic alterations associated with resistance to EGFR monoclonal antibodies (mAb) in real-world patients with metastatic colorectal cancer (mCRC).

52 Background: mCRC patients with RAS and BRAF mutant tumors do not benefit from treatment with EGFR mAb. However, some RAS/BRAF wild-type patients do not benefit from EGFR mAbs. We sought to investigate additional primary and acquired biomarkers of resistance to EGFR mAb in mCRC. We hypothesized (1) alterations in pre-specified genes of known biological but unconfirmed clinical significance are associated with less favorable outcomes in patients treated with EGFR mAb; (2) these alterations are acquired during treatment and are associated with the time of exposure to these drugs. Methods: We included mCRC patients with RAS/ BRAF wild-type tumors receiving EGFR mAb (cetuximab or panitumumab) in 1st line (1L, n = 248) or in 2L+ of therapy (n = 2,118). This study used the US-based de-identified Flatiron Health-Foundation Medicine real-world mCRC clinico-genomic database, originating from ~280 US cancer clinics between 01/2011 and 04/2022. Pre-specified genes included PIK3CA, PTEN, MAP2K1, and RTKs. Real-world progression-free survival (rwPFS) and overall survival (rwOS) were compared between patients +/- alterations by Cox models, adjusted for a risk score generated from known clinical prognostic features. Alterations were compared between patients with biopsies collected before and after starting treatment with EGFR mAb by chi-square, adjusted for multiple comparisons. The association between the amount of time on drug exposure and alterations was evaluated by linear regression. Results: Patients with RTK/ MAP2K1 alterations (n = 38, 15.3%) had less favorable outcomes (PFS HR 1.83, 95% CI 1.27-2.65, p = 0.001/ OS HR 1.59, 95% CI 1.00-2.51, p = 0.048). The same trend was observed for patients with PIK3CA/ PTEN alterations (n = 31, 12.5%, PFS HR 1.35, 95% CI 0.89-2.03, p = 0.155/ OS HR 1.75, 95% CI 1.08 -2.85, p = 0.024) and ERBB2amp (n = 21, 8.5%, PFS HR 1.52, 95% CI 0.93-2.5, p = 0.096/ OS HR 1.33, 95% CI 0.71-2.5, p = 0.373). Compared to biopsies obtained before (n = 1,834), those obtained after treatment initiation were enriched for RTK alterations (n = 284, +9%, p = 0.001), especially for METamp (+3%, p = 0.04). Compared to unexposed patients, patients exposed to EGFR inhibitors had higher odds (p &lt; 0.001) of developing RTK alterations (OR: 1.84, 95% CI 1.54-2.19; OR 3.33, 95% CI 2.60-4.24; and OR 2.28, 95% CI 1.56-3.26 for 0-12, 12-24, and 24+ months of exposure, respectively). Additional analyses will be presented. Conclusions: RAS/RAF WT mCRC patients with baseline alterations in RTK genes have less favorable outcomes on EGFR inhibitors (intrinsic resistance), and post-EGFR mAb samples (acquired resistance) converge around RTK and MAPK alterations, particularly MET, in real-world data.

A Sensitive Surface-Plasmon-Resonance (SPR)-Immunosensor Based on Multilayers of Graphene Oxide and Gold Nanoparticles for Epidermal Growth Factor Receptor Detection

In the last two decades, the use of biosensors, especially in medical sciences, has received increasing attention. In this study, we presented a novel surface-plasmon-resonance (SPR)-based optical biosensor that can be applied for the sensitive detection of epidermal growth factor receptor (EGFR). For the construction of this immunosensor, an anti-human EGFR monoclonal antibody (anti-EGFR mAb) was immobilized on a modified glassy slide with gold nanoparticles (AuNPs) followed by four layers of graphene oxide [(GO)4]. The fabricated sensor consisting of (EGFR/AbEGFR/(GO)4/AuNPs/glassy slide) was evaluated by spectroscopy. Following the attachment of the target protein with Ab (EGFR/Ab/(GO)4/AuNPs/glassy slide), the SPR signal of AuNPs is recorded and used as an analytical signal for quantifying EGFR. The relationship between EGFR concentration and relative absorbance is linear within the range of 0–100 pg/mL, with a detection limit of 0.65 pg/mL. The immunosensor performed well in terms of sensitivity, selectivity, stability, and reproducibility, and it was shown to be appropriate for measuring EGFR directly in human blood samples.

Radiotherapy Plus Temozolomide With or Without Nimotuzumab Against the Newly Diagnosed EGFR-Positive Glioblastoma: A Retrospective Cohort Study.

Glioblastoma (GBM) has a poor prognosis, and patients with epidermal growth factor receptor (EGFR) amplification have an even worse prognosis. Nimotuzumab is an EGFR monoclonal antibody thought to play a significant role in the treatment of GBM. This paper presents a retrospective cohort study that evaluates the clinical efficacy and safety of nimotuzumab in GBM. A total of 56 newly diagnosed patients with EGFR-positive GBM were included in our study. The patients were divided into radiotherapy (RT) + temozolomide (TMZ) + nimotuzumab (39 patients) and RT + TMZ (17 patients) groups based on whether or not nimotuzumab was added during RT. Progression-free survival (PFS), overall survival (OS), and toxicities were assessed. The median follow-up time was 27.9 months (95% confidence interval [CI], 25.1-30.8). The median PFS was 12.4 months (95% CI, 7.8-17.0) and 8.2 months (95% CI, 6.1-10.3) in the 2 groups, respectively, P = .052. The median OS was 27.3 months (95% CI, 19.0-35.6) and 16.7 months (95% CI, 11.1-22.2), respectively, P = .018. In patients with unmethylated O6-methylguanine-DNA methyltransferase (MGMT) promoter, the PFS and OS were significantly better in patients treated with nimotuzumab than in those without nimotuzumab (median PFS: 19.3 vs 6.7 months, P = .001; median OS: 20.2 vs 13.8 months, P = .026). During the treatment period, no statistically significant difference in toxicity was noted between the 2 groups. Our retrospective cohort study suggests the efficacy of Nimotuzumab combined with concurrent RT with TMZ in patients with newly diagnosed EGFR-positive GBM, and specifically those with unmethylated MGMT promoter. Further prospective studies are warranted to validate our findings. Besides, nimotuzumab demonstrated good safety and tolerability.

390P Impact of age on treatment strategies in RAS/BRAF wild-type metastatic colorectal cancer (mCRC): A prespecified subgroup analysis of the GERCOR-PRODIGE STRATEGIC-1 phase III study

Nearly half of patients (pts) with CRC are over 70 years old in clinical practice. STRATEGIC-1 compared FOLFIRI-cetuximab followed by mFOLFOX6-bevacizumab (Arm A) to OPTIMOX-bevacizumab followed by FOLFIRI-bevacizumab and EGFR monoclonal antibody +/- irinotecan (Arm B) in pts with previously untreated RAS/BRAF wild-type unresectable mCRC. To elucidate the impact of age on treatment efficacy, we evaluated duration of disease control (DDC) and overall survival (OS). A subgroup analysis of pts ≥70 years old was preplaned. Pts were divided into two age groups, <70 and ≥70 years, at the time of diagnosis. DDC and OS were expressed by the Kaplan-Meier method and compared by log-rank testing and Cox regression. In the general population (N=263), 187 pts (71%) and 76 pts (29%) were <70 and ≥70 years old, respectively. In Arm A (N=131) and in Arm B (N=132), 35 pts (27%) and 41 pts (31%) were ≥70 years old, respectively. Subgroup analysis showed that age had similar prognostic value in terms of DDC (22.0 months in younger vs 25.3 months in elderly [HR=0.91, 0.66-1.25; P=0.553]) and OS (36.5 months vs 34.9 months [HR=1.08, 0.78-1.48; P=0.648], respectively). Although OS was significantly improved in Arm A (HR=1.45, 1.02-2.08; P=0.039) in <70 pts, median OS was better in Arm B in ≥70 pts (42.1 vs 33.7 months; but statistically non-significant [P=0.161]). The effect of age on the treatment efficacy is shown in Table.Table: 390PPts <70 yearsPts ≥70 yearsArm AArm BHR (95%CI)PArm AArm BHR (95%CI)PNo.96913541DDC, median (months)22.820.91.05 (0.75-1.48)0.76422.528.90.83 (0.48-1.42)0.483OS, median (months)42.631.71.45 (1.02-2.08)0.03933.742.10.90 (0.53-1.53)0.161 Open table in a new tab These results confirm the polychemotherapy regimens efficiency associated to targeted therapies despite of the age, but elderly were underrepresented in trial compared to real life. The best choice of first-line chemotherapy in older pts remains unclear. The COLAGE GERCOR study, assessing the quality of life in elderly treated by FOLFOX-bevacizumab vs the standard first-line treatment (capecitabine-bevacizumab), and further studies are needed to better target elderly with mCRC.