Highly drug/target-tolerant neutralizing antibody (NAb) assay development through target-based drug depletion and drug-based NAb extraction for an anti-EGFR therapeutic monoclonal antibody

The reduction of immunogenicity is fundamental for the development of biobetter Erbitux, given that the development of an immune response reduces treatment efficacy and may lead to potential side effects. One of the requirements for the clinical research of a Erbitux biobetter candidate (CMAB009) is to develop a neutralizing antibody (NAb) assay, and sufficient drug and target tolerance for the assay is necessary. Here, we describe the development of a competitive ligand binding (CLB) assay for CMAB009 with high drug and target tolerance through target-based drug depletion and drug-based NAb extraction, the integrated experimental strategy was implemented to simultaneously mitigate drug interference and enhance target tolerance. Following troubleshooting and optimization, the NAb assay was validated for clinical sample analysis with the sensitivity of 92 ng/mL, drug tolerance of 70 μg/mL and target tolerance of 798 ng/mL. The innovative drug depletion and NAb extraction achieved though the combination of drug and target beads would enable the development of reliable NAb assays for many other therapeutics that overcome drug and its target interference for more precise and sensitive NAb assessment.

Study protocol: phase II study to evaluate the effect of cetuximab monotherapy after immunotherapy with PD-1 inhibitors in patients with head and neck squamous cell cancer

Background

Immunotherapy with programmed death receptor-1 (PD-1) inhibitors, as a single agent or in combination with chemotherapy, is the standard first-line treatment for recurrent or metastatic head and neck squamous cell cancer (R/M HNSCC). Unfortunately, there is no established second-line treatment for the many patients who fail immunotherapy. Cetuximab is the only targeted therapy approved in HNSCC but historically has a low response rate of 13%.

Objectives

We hypothesize that cetuximab monotherapy following an immune checkpoint inhibitor (ICI) will lead to increased efficacy due to a potential synergistic effect on the antitumor immune response, as a result of activation effects of both treatments on innate and adaptative immune responses. To the authors' knowledge, this is the only ongoing prospective clinical study that evaluates the combination of cetuximab and ICIs administered sequentially.

Methods and analysis

In this non-randomized, open-label, phase II trial, 30 patients with R/M HNSCC who have previously failed or could not tolerate a PD-1 inhibitor as a single agent or in combination with chemotherapy will subsequently be treated with cetuximab monotherapy. Outcomes of interest include overall response rate, duration of response, progression-free survival, overall survival, and treatment toxicity, as well as treatment outcome measured by a patient-reported outcome questionnaire. Saliva and blood will be collected for correlative studies to investigate the immune response status at the end of therapy with an ICI and the effect of cetuximab on the antitumor immune response. The results will be correlated with the response to cetuximab and the time window between the last administration of an ICI and the loading dose of cetuximab. The clinical study is actively recruiting.

Ethics

This study was approved by the Wake Forest Comprehensive Cancer Center Institutional Review Board: IRB00065239.

Clinical trial registration

This study is registered on ClinicalTrials.gov: NCT04375384.

Theranostic potential of self-luminescent branched polyethyleneimine-coated superparamagnetic iron oxide nanoparticles

Polyethylenimine (PEI), which is frequently used for polyplex formation and effective gene transfection, is rarely recognized as a luminescent polymer. Therefore, it is usually tagged with an organic fluorophore to be optically tracked. Recently, we developed branched PEI (bPEI) superparamagnetic iron oxide nanoparticles (SPION@bPEI) with blue luminescence 1200 times stronger than that of bPEI without a traditional fluorophore, due to partial PEI oxidation during the synthesis. Here, we demonstrate in vitro dye-free optical imaging and successful gene transfection with luminescent SPION@bPEI, which was further modified for receptor-mediated delivery of the cargo selectively to cancer cell lines overexpressing the epidermal growth factor receptor (EGFR). Pro-apoptotic polyinosinic-polycytidylic acid sodium (PIC) was delivered to HeLa cells with SPION@bPEI and caused a dramatic reduction in the cell viability at otherwise non-toxic nanoparticle concentrations, proving that bPEI coating is still an effective component for the delivery of an anionic cargo. Besides, a strong intracellular optical signal supports the optically traceable nature of these nanoparticles. SPION@bPEI nanoparticles were further conjugated with Erbitux (Erb), which is an anti-EGFR antibody for targeting EGFR-overexpressing cancer cell lines. SPION@bPEI-Erb was used for the delivery of a GFP plasmid wherein the transfection was confirmed by the luminescence of the expressed gene within the transfected cells. Poor GFP expression in MCF7, a slightly better expression in HeLa, and a significant enhancement in the transfection of HCT116 cells proved a selective uptake and hence the targeting ability of Erb-tagged nanoparticles. Altogether, this study proves luminescent, cationic, and small SPION@bPEI nanoparticles as strong candidates for imaging and gene therapy.

Cetuximab response in CRC patient-derived xenografts seems predicted by an expression based RAS pathway signature

Cetuximab is an approved treatment for metastatic colorectal carcinoma (mCRC) with codon 12/13-KRAS mutations, recently questioned for its validity, and alternative mutation-based biomarkers were proposed. We set out to investigate whether an expression signature can also predict response by utilizing a cetuximab mouse clinical trial (MCT) dataset on a cohort of 25 randomly selected EGFR⁺ CRC patient-derived xenografts (PDXs). While we found that the expression of EGFR and its ligands are not predictive of the cetuximab response, we tested a published RAS pathway signature, a 147-gene expression signature proposed to describe RAS pathway activity, against this MCT dataset. Interestingly, our study showed that the observed cetuximab activity has a strong correlation with the RAS pathway signature score, which was also demonstrated to have a certain degree of correlation with a historic clinical dataset. Altogether, the independent validations in unrelated datasets from independent cohort of CRCs strongly suggest that RAS pathway signature may be a relevant expression signature predictive of CRC response to cetuximab. Our data seem to suggest that an mRNA expressing signature may also be developed as a predictive biomarker for drug response, similarly to genetic mutations.

NSCLC harboring EGFR exon-20 insertions after the regulatory C-helix of kinase domain responds poorly to known EGFR inhibitors

Anecdote clinical observations hint that non-small cell lung cancer (NSCLC) with exon-20 insertions might respond poorly to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), contrasting to those with classic mutations. Lack of patient-derived experimental models has been a major hurdle for the discovery of new treatment for the diseases. We established two NSCLC-PDXs harboring two different exon-20 insertions, LU0387-adenocarcinoma (ADC) with a nine-base insertion at 2319 (H773-V774insNPH) and LU3075-squamous cell carcinoma (SCC) with a nine-base insertion at 2316 (P772-H773insDNP). Both insertions immediately follow the regulatory C-helix of the kinase domain. Contrary to the generally good responses to EGFR inhibitors observed in PDXs with classic mutations, both exon-20 insertions are largely resistant to cetuximab and TKIs in vivo, suggesting fundamental difference from the classic EGFR mutations, consistent with the poor response rate to TKI seen in anecdotal clinic reports. It is worth noting that although responses are generally poor, they differ between the two exon-20 mutants depending on the type of TKI. In vitro drug sensitivity assays using established primary cell lines from our two PDXs largely confirmed the in vivo data. Our data from patient-derived experimental models confirmed that exon-20 insertions in domain immediately following the C-helix confer poor response to all known EGFR inhibitors, and suggested that these models can be utilized to facilitate the discovery of new therapies targeting NSCLC harboring exon-20 insertions.

Antitumor effect and safety profile of systemically delivered oncolytic adenovirus complexed with EGFR-targeted PAMAM-based dendrimer in orthotopic lung tumor model

Adenovirus (Ad)-mediated cancer gene therapy has been proposed as a promising alternative to conventional therapy for cancer. However, success of systemically administered naked Ad has been limited due to the immunogenicity of Ad and the induction of hepatotoxicity caused by Ad's native tropism. In this study, we synthesized an epidermal growth factor receptor (EGFR)-specific therapeutic antibody (ErbB)-conjugated and PEGylated poly(amidoamine) (PAMAM) dendrimer (PPE) for complexation with Ad. Transduction of Ad was inhibited by complexation with PEGylated PAMAM (PP) dendrimer due to steric hindrance. However, PPE-complexed Ad selectively internalized into EGFR-positive cells with greater efficacy than either naked Ad or Ad complexed with PP. Systemically administered PPE-complexed oncolytic Ad elicited significantly reduced immunogenicity, nonspecific liver sequestration, and hepatotoxicity than naked Ad. Furthermore, PPE-complexed oncolytic Ad demonstrated prolonged blood retention time, enhanced intratumoral accumulation of Ad, and potent therapeutic efficacy in EGFR-positive orthotopic lung tumors in comparison with naked Ad. We conclude that ErbB-conjugated and PEGylated PAMAM dendrimer can efficiently mask Ad's capsid and retarget oncolytic Ad to be efficiently internalized into EGFR-positive tumor while attenuating toxicity induced by systemic administration of naked oncolytic Ad.

Comparative hyperthermia effects of silica-gold nanoshells with different surface coverage of gold clusters on epithelial tumor cells

Silica–gold nanoshell (SGNS), which is a silica core surrounded by a gold layer, was synthesized by seed-mediated coalescence of gold clusters in an electroless plating solution. SGNS variations with different surface coverage of gold clusters were prepared by adjusting the amounts of gold salts in the presence of formaldehyde-reducing agents. Fully covered SGNS (f-SGNS) with connected gold clusters exhibited stronger intensity and more redshift of plasmon bands located around 820 nm than those of partially covered SGNS (p-SGNS) with disconnected gold clusters. Upon irradiation with near-infrared light (30 W/cm², 700–800 nm), f-SGNS caused a larger hyperthermia effect, generating a large temperature change (ΔT =42°C), as compared to the relatively small temperature change (ΔT =24°C) caused by p-SGNS. The therapeutic antibody, Erbitux™ (ERB), was further conjugated to SGNS for specific tumor cell targeting. The f-ERB-SGNS showed excellent therapeutic efficacy based on the combined effect of both the therapeutic antibody and the full hyperthermia dose under near-infrared irradiation. Thus, SGNS with well-controlled surface morphology of gold shells may be applicable for near-infrared-induced hyperthermia therapy with tunable optical properties.

Changes of TCR repertoire diversity in colorectal cancer after Erbitux (cetuximab) in combination with chemotherapy

We have previous found a positive correlation between post-therapy TCR repertoire normalization and remission of colorectal cancer (CRC) patients following fluorouracil, leucovorin, and irinotecan (FOLFIRI) plus bevacizumab or Rh-endostatin therapy. To further define the TCR repertoire diversity changes following treatment in CRC patients, and confirm its potential prognostic value, the present study extended the sample size of follow-up and used an alternative therapy regime to investigate changes of TCR repertoires following Erbitux plus FOLFIRI therapy. Inclusion and exclusion criteria have been established to screen out 26 patients to receive Erbitux plus FOLFIRI therapy. Efficacy and toxicity assessment have been made for them after 3 months' treatment as well as the TCR repertoire diversity has been determined. A CDR3 complex scoring system was used to quantify the diversity of TCR repertoire. The results showing that the diversity of CD4(+) T cells in PR group was significantly higher than that of SD and PD groups, and the difference was enlargement after treatment. The diversity of CD8(+) T cells in PR group has no difference before and after treatment, but significant decrease in SD and PD group after treatment. In conclusion, analysis the diversity of T cell repertoire has an important prognosis value for CRC patients.

EGFR expression and survival in patients given cetuximab and chemoradiation for stage III non-small cell lung cancer: a secondary analysis of RTOG 0324

PURPOSE

We investigated whether expression of epidermal growth factor receptor (EGFR) was associated with survival and disease control in this secondary analysis of a phase II trial of cetuximab+chemoradiation for stage III non-small cell lung cancer.

METHODS

Patients received cetuximab weekly before and during radiation (63 Gy/35 fractions/7 weeks) with weekly carboplatin + paclitaxel. We analyzed EGFR expression by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) in pretreatment biopsy specimens and compared findings with overall and progression-free survival (OS, PFS) and time to progression (TTP).

RESULTS

Specimens for IHC and FISH were collected from 51 and 45 of 87 evaluable patients. Pretreatment characteristics did not differ for patients with (n = 51) or without (n= 36) EGFR IHC data, or with (n = 45) or without (n = 42) FISH data. However, patients without IHC data had worse OS (HR = 1.63, P = 0.05), worse PFS (HR = 1.88, P = 0.008), and worse TTP [HR = 1.99, P = 0.01] than those with IHC data. EGFR protein expression was not related to pretreatment characteristics or OS; FISH-positive disease was associated with better performance status but not with OS, PFS, or TTP.

CONCLUSIONS

Surprisingly, outcomes differed not by EGFR expression but by the availability of samples for analysis, underscoring the importance of obtaining biopsy samples in such trials.

Incidence of cetuximab-related infusion reactions in oncology patients treated at the University of North Carolina Cancer Hospital

PURPOSE

The primary purpose of this study was to determine the rate of infusion reactions to cetuximab in oncology patients treated at the University of North Carolina Cancer Hospital. Secondarily, we sought to evaluate predictors of grade 3-4 hypersensitivity, including geography.

METHODS

Data were collected by retrospective chart review for patients treated with cetuximab at the University of North Carolina Cancer Hospital between 15 November 2006 and 31 December 2010. Data were analyzed for occurrence of hypersensitivity reaction in 125 patients with various cancer types.

RESULTS

Of the 125 subjects, 31 (24.8%) experienced an infusion reaction of any grade. Of 125, 18 (14.4%) experienced a grade 3 or 4 reaction. The odds ratio for patients with an allergy history having a grade 3 or 4 reaction was 2.57 (95% CI 0.93 to 7.09, p = 0.07). Pretreatment with steroids was associated with absence of grade 3 or 4 reaction with an odds ratio of 0.21 (95% CI 0.05 to 0.83, p = 0.04). Mapping of reaction rates by county revealed higher rates in some of the more rural counties of North Carolina, however, statistical power was lacking.

CONCLUSIONS

Rates of hypersensitivity reaction at UNC are similar to rates seen in other areas of the southeastern United States and higher than in other regions of the United States and Europe. Rates of both hypersensitivity reactions and grade 3 to 4 hypersensitivity reactions have not substantially changed over time. Geography, allergy history, and perhaps smoking or cancer type may help predict who will react to cetuximab. Steroids should be strongly considered as premedication in addition to diphenhydramine.