Cetuximab-mediated tumor regression depends on innate and adaptive immune responses.

Epidermal growth factor receptor (EGFR) over-signaling leads to more aggressive tumor growth. The antitumor effect of Cetuximab, an anti-EGFR antibody, depends on oncogenic-signal blockade leading to tumor cell apoptosis and antibody dependent cell-mediated cytotoxicity (ADCC). However, whether adaptive immunity plays a role in Cetuximab-mediated tumor inhibition is unclear, as current xenograft models lack adaptive immunity and human-EGFR-dependent mouse tumor cell lines are unavailable. Using a newly developed xenograft model with reconstituted immune cells, we demonstrate that the Cetuximab effect becomes more pronounced and reduces the EGFR(+) human tumor burden when adaptive immunity is present. To further study this in a mouse tumor model, we created a novel EGFR(+) mouse tumor cell line and demonstrated that Cetuximab-induced tumor regression depends on both innate and adaptive immunity components, including CD8(+) T cells, MyD88, and FcγR. To test whether strong innate signals inside tumor tissues amplifies the Cetuximab-mediated therapeutic effect, Cetuximab was conjugated to CpG. This conjugate is more potent than Cetuximab alone for complete tumor regression and resistance to tumor rechallenge. Furthermore, Cetuximab-CpG conjugates can activate tumor-reactive T cells for tumor regression by increasing dendritic cell (DC) cross-presentation. Therefore, this study establishes new models to evaluate immune responses induced by antibody-based treatment, defines molecular mechanisms, and provides new tumor-regression strategies.

A Randomized, Single-Dose, Parallel-Controlled Phase 1 Clinical Comparison of an Omalizumab Biosimilar Candidate with Reference Omalizumab in Healthy Chinese Male Volunteers.

This study evaluated the bioequivalence of omalizumab, a humanized monoclonal antibody against immunoglobulin-E (IgE), with one of its biosimilar candidates. The study was designed as a randomized, double-blind, parallel-controlled trial. A total of subjects who met the inclusion criteria and did not meet the exclusion criteria were dynamically randomly assigned to receive the test drug or the reference drug with a single subcutaneous injection of 150 mg by the minimization method. The test group and the reference group had similar demographic characteristics and baseline characteristics of total IgE. The 90% confidence interval of the geometric average ratio of the area under the serum concentration-time curve from the time 0 to the time of last quantifiable concentration, the area under the serum concentration curve from time 0 to infinity, and the maximum observed serum concentration between the 2 groups were within 80%-125%, showing bioequivalence. The changing trend of total and free IgE in the 2 groups was similar after administration, proving the pharmacodynamic similarity. The 2 groups had no significant difference in the positive rate of antidrug antibodies, and the total positive rate of neutralizing antibodies was 0. The incidence of treatment-emergent adverse events and treatment-related adverse events were similar between the 2 groups, with no serious adverse events. This study shows that the test drug had similar pharmacokinetics, immunogenicity, and safety to the reference omalizumab in healthy male subjects.

A Randomized, Double-Blind, Parallel-Group Phase I Study Comparing the Pharmacokinetics, Safety, and Immunogenicity of CMAB015, a Candidate Secukinumab Biosimilar, with Its Reference Product Cosentyx® in Healthy Chinese Male Subjects.

Purpose: Secukinumab, a monoclonal antibody targeting interleukin (IL)-17A, is approved for the treatment of psoriasis, psoriatic arthritis, ankylosing spondylitis, non-radiographic axial spondyloarthritis, enthesitis-related arthritis, and hidradenitis suppurativa. This study compared the pharmacokinetics (PK), safety, and immunogenicity of CMAB015, a candidate secukinumab biosimilar, with the reference product secukinumab (Cosentyx®) in healthy Chinese male subjects. Patients and methods: This double-blind, parallel-group study randomized healthy Chinese male subjects (N=130) to receive either a single dose of 150 mg CMAB015 or secukinumab subcutaneously. Primary study endpoints were PK parameters such as the maximum concentration (Cmax) and area under the curve from zero to infinity (AUC0-inf), while safety and immunogenicity were secondary endpoints. Results: The 90% confidence intervals (CIs) of the geometric mean ratios (GMRs) of Cmax and AUC0-inf for CMAB015 to secukinumab were all within the bioequivalence limits (80.00-125.00%). Other PK parameters were comparable between the groups. The safety profile of CMAB015 was similar to that of secukinumab, with no serious adverse events related to treatment. The incidence of TEAEs was slightly higher in the CMAB015 group, but these events were mild to moderate in severity and did not lead to any withdrawals from the study. Immunogenicity analysis revealed low rates of anti-drug antibody (ADA) positivity, with similar rates between CMAB015 and secukinumab. Conclusion: This study demonstrated equivalent PK, comparable safety, and immunogenicity of CMAB015 to secukinumab in healthy Chinese male subjects. These findings support further clinical evaluation of CMAB015 as a secukinumab biosimilar. Trial Registration: The trial was registered on Clinicaltrials.gov (Identifier No. NCT05734482) and Chinadrugtrials.org.cn (Identifier No. CTR20230105).

Population Pharmacokinetics of CMAB008 (an Infliximab Biosimilar) and Remicade® in Healthy Subjects and Patients with Moderately to Severely Active Rheumatoid Arthritis.

INTRODUCTION: CMAB008 is a monoclonal antibody developed as a biosimilar to infliximab (Remicade®, Janssen). The pharmacokinetic characteristics of CMAB008 and Remicade® in healthy subjects and patients with moderately to severely active rheumatoid arthritis (RA) were investigated using a population modeling approach, and the pharmacokinetic similarity of CMAB008 to Remicade® was assessed. METHODS: The population pharmacokinetic model was developed on the basis of intensive pharmacokinetic data from a phase 1 study in healthy male subjects and combined intensive and sparse pharmacokinetic data from a phase 3 study in patients with RA. RESULTS: A two-compartment model with first-order elimination adequately described CMAB008 and Remicade® concentration data in healthy subjects and patients with RA. The analysis of covariates identified anti-drug antibody (ADA), neutralizing antibody (NAB), real-time body weight (BWT), and real-time albumin (ALB) as significant covariates on clearance, and BWT was also a significant covariate for the central volume of distribution. The treatment type (CMAB008 versus Remicade®) and the study population (healthy subjects versus patients with RA) were not identified as significant covariates on the pharmacokinetics of infliximab, demonstrating pharmacokinetic similarity between CMAB008 and Remicade® in both study populations. The effect of BWT and ALB changes on exposures to infliximab was within the acceptable range, suggesting that the 3 mg/kg regimen is appropriate in clinical practice for patients with RA and BTW and ALB distribution within the range evaluated in the current analysis. CONCLUSIONS: The pharmacokinetic characteristics were similar between CMAB008 and Remicade® in healthy subjects and patients with RA. CMAB008 can be considered bioequivalent to Remicade®. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifiers NCT04779892, NCT03478111.

Pharmacokinetics, Pharmacodynamics, Safety and Immunogenicity of CMAB807, a New Denosumab Biosimilar, in Healthy Chinese Subjects.

Objective: Pharmacokinetics (PK), pharmacodynamics (PD), safety and immunogenicity studies were conducted to evaluate the bioequivalence of CMAB807, a biosimilar to denosumab (Prolia®), which is the only approved RANKL inhibitor for the treatment of osteoporosis. Methods: In this randomized, double-blind, single-dose phase I study, 132 healthy Chinese male subjects received a subcutaneous injection of 60 mg of CMAB807 or denosumab at a 1:1 ratio. The PK, PD, safety and immunogenicity results were assessed prior to and up to 126 days after administration. Results: The PK profiles of CMAB807 and denosumab were similar. The geometric mean ratios of the maximum concentration (Cmax), AUC0-t and AUCo-∞ were 102.41, 104.15 and 103.89%, respectively, and the 90% confidence interval was observed to be within 80.00-125.00%, which indicated the bioequivalence of CMAB807 and denosumab. The PD profiles of the two groups were also comparable. The production of the C-terminal cross-linking telopeptide of type I collagen (CTX1) was inhibited by up to 85% for 10 days, and this inhibition was sustained for up to 126 days in both the CMAB807 and denosumab groups. No subjects in the CMAB807 group, three subjects in the denosumab group before administration, and two subjects in the denosumab group after administration were positive for anti-drug antibody (ADA). Adverse events (AEs) were observed in 98.5% of subjects in both groups. The most common AE recorded was increased parathyroid hormone (PTH) levels, with incidences of 92.4 and 95.5% in the CMAB807 and denosumab groups, respectively. No clinically meaningful differences were observed in safety and immunogenicity between CMAB807 and denosumab. Conclusion: CMAB807 represents a new potential treatment option for patients with osteoporosis. Clinical Trial Registration: https://clinicaltrials.gov (Registration No. NCT03925051), http://www.chinadrugtrial/org.cn/index.html (Registration No. CTR20190800).

Development and characterization of a novel anti-IgE monoclonal antibody.

IgE is the central macromolecular mediator responsible for the progression of allergic reactions. Omalizumab (Xolair) is a humanized monoclonal anti-IgE antibody directed at the FcepsilonRI-binding domain of human IgE, which represents a novel therapeutic approach in the management of asthma. In this study, we developed a monoclonal antibody (7A5) against human IgE via hybridoma technique. Our data showed that 7A5 could inhibit free IgE molecules to bind to receptors without affecting IgE already bound to cellular receptors. Importantly, 7A5 was able to inhibit IgE-induced histamine release of basophilic leukemia cells. Next, the phage display peptide library technology was employed to select peptides binding to 7A5 and a striking peptide sequence motif was recovered, which is homologous to the sequence (391)KQR(393) within the Cepsilon3 domain of IgE-Fc, Our results further indicated that 7A5 specifically bound to the synthesized peptide "(388)KEEKQRN(394)" containing the (391)KQR(393) motif in IgE-Fc. The epitope of 7A5 was found to be spatially close to the FcepsilonRI-binding site, suggesting that 7A5 binding to IgE might block IgE binding to receptors via steric hindrance. The anti-IgE monoclonal antibody 7A5 may have the potential to be developed as a therapeutic agent for the treatment of allergic diseases.

A BTLA-mediated bait and switch strategy permits Listeria expansion in CD8α(+) DCs to promote long-term T cell responses.

Listeria monocytogenes infected CD8α(+) DCs in the spleen are essential for CD8(+) T cell generation. CD8α(+) DCs are also necessary for Listeria expansion and dissemination within the host. The mechanisms that regulate CD8α(+) DCs to allow Listeria expansion are unclear. We find that activating the B and T lymphocyte attenuator (BTLA), a coinhibitory receptor for T cells, suppresses, while blocking BTLA enhances, both the primary and memory CD8 T cell responses against Listeria. Btla(-/-) mice have lower effector and memory CD8(+) T cells while paradoxically also being more resistant to Listeria. Although bacterial entry into Btla(-/-) CD8α(+) DCs is unaffected, Listeria fails to expand within these cells. BTLA signaling limits Fas/FasL-mediated suppression of Listeria expansion within CD8α(+) DCs to more effectively alert adaptive immune cells. This study uncovers a BTLA-mediated strategy used by the host that permits Listeria proliferation to enable increasing T cell responses for long-term protection.

Targeting the tumor microenvironment with interferon-ß bridges innate and adaptive immune responses.

Antibodies (Abs) that preferentially target oncogenic receptors have been increasingly used for cancer therapy, but tumors often acquire intrinsic Ab resistance after prolonged and costly treatment. Herein we armed the Ab with IFNß and observed that it is more potent than the first generation of Ab for controlling Ab-resistant tumors. This strategy controls Ab resistance by rebridging suppressed innate and adaptive immunity in the tumor microenvironment. Mechanistically, Ab-IFNß therapy primarily and directly targets intratumoral dendritic cells, which reactivate CTL by increasing antigen cross-presentation within the tumor microenvironment. Additionally, blocking PD-L1, which is induced by Ab-IFNß treatment, overcomes treatment-acquired resistance and completely eradicates established tumors. This study establishes a next-generation Ab-based immunotherapy that targets and eradicates established Ab-resistant tumors.

The ErbB2-targeting antibody trastuzumab and the small-molecule SRC inhibitor saracatinib synergistically inhibit ErbB2-overexpressing gastric cancer.

The anti-ErbB2 antibody trastuzumab has shown significant clinical benefits in ErbB2-overexpressing breast and gastric cancer, but resistance to the drug is common. Here, we investigated the antitumor activity of the combination of trastuzumab and the SRC inhibitor saracatinib in ErbB2-overexpressing trastuzumab-resistant gastric cancer. The ErbB2-overexpressing human gastric cancer cell line NCI-N87 was treated with trastuzumab to obtain the trastuzumab-resistant cell line NCI-N87R. The NCI-N87R cell line showed a marked increase in SRC activity and ErbB signaling compared with the NCI-N87 cell line. Our data demonstrated that trastuzumab plus saracatinib was much more potent than either agent alone in reducing the phosphorylation of ErbB3 and AKT in both NCI-N87 and NCI-N87R gastric cancer cell lines. Trastuzumab and saracatinib synergistically inhibited the in vitro growth of NCI-N87 and NCI-N87R cell lines. Further data showed that combination therapy of trastuzumab with saracatinib resulted in a significant benefit over either agent alone in both NCI-N87 and NCI-N87R xenograft models, suggesting its potential use for treating ErbB2-overexpressing gastric cancer.

Bispecific antibody to ErbB2 overcomes trastuzumab resistance through comprehensive blockade of ErbB2 heterodimerization.

The anti-ErbB2 antibody trastuzumab has shown significant clinical benefits in metastatic breast cancer. However, resistance to trastuzumab is common. Heterodimerization between ErbB2 and other ErbBs may redundantly trigger cell proliferation signals and confer trastuzumab resistance. Here, we developed a bispecific anti-ErbB2 antibody using trastuzumab and pertuzumab, another ErbB2-specific humanized antibody that binds to a distinct epitope from trastuzumab. This bispecific antibody, denoted as TPL, retained the full binding activities of both parental antibodies and exhibited pharmacokinetic properties similar to those of a conventional immunoglobulin G molecule. Unexpectedly, TPL showed superior ErbB2 heterodimerization-blocking activity over the combination of both parental monoclonal antibodies, possibly through steric hindrance and/or inducing ErbB2 conformational change. Further data indicated that TPL potently abrogated ErbB2 signaling in trastuzumab-resistant breast cancer cell lines. In addition, we showed that TPL was far more effective than trastuzumab plus pertuzumab in inhibiting the growth of trastuzumab-resistant breast cancer cell lines, both in vitro and in vivo. Importantly, TPL treatment eradicated established trastuzumab-resistant tumors in tumor-bearing nude mice. Our results suggest that trastuzumab-resistant breast tumors remain dependent on ErbB2 signaling and that comprehensive blockade of ErbB2 heterodimerization may be an effective therapeutic avenue. The unique potential of TPL to overcome trastuzumab resistance warrants its consideration as a promising treatment in the clinic.

Development and characterization of a fully functional small anti-HER2 antibody.

The penetrating of monoclonal antibodies (mAbs) into solid tumor may be hampered by their large size. The antibody mimetics, composed of two complementarity-determining regions (CDRs) through a cognate framework region (FR), have been demonstrated to have the capacity to penetrate tumors superior to its parental intact IgG. In this study, we used CDR and FR sequences from the humanized anti-HER2 monoclonal antibody trastuzumab to design four antibody mimetics. Then these antibody mimetics were fused to human IgG Fc to generate mimetics-Fc small antibodies. One of the four mimetics-Fc antibodies binds well to HER2-overexpressing SK-BR3 cells and effectively inhibits the binding of trastuzumab. This mimetics-Fc, denoted as HMTI-Fc, was shown to be effective in mediating antibody-dependent cellular cytotoxicity and exhibit an antiproliferative effect in SK-BR3 cells. To our knowledge, the HMTI-Fc antibody shown here is the smallest fully functional antibody and may have a potential for treatment of cancer.