Modified response evaluation criteria in solid tumors: A better response evaluation criteria for patients with non-squamous non-small cell lung cancer after bevacizumab treatment.

AIM: Cavitation of lesions is common in non-squamous non-small cell lung cancer (non-squamous-NSCLC) patients treated with vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFRIs). However, traditional response evaluation criteria in solid tumors (RECIST) do not take cavitation into consideration and may no longer be accurate for potentially reflecting the real clinical efficacy of anti-vessel growth therapy. Here, we aimed to optimize the traditional RECIST version 1.1 by adding cavitation into the evaluation criteria. METHODS: We performed a post-hoc radiologic review of 517 patients in a phase III clinical trial of bevacizumab biosimilar (SIBP04) combined with chemotherapy for the treatment of non-squamous NSCLC. Tumor responses were assessed by RECIST1.1 and mRECIST criteria (modified RECIST, a novel alternate method where the longest diameter of the cavity was subtracted from the overall longest diameter of that lesion to measure target lesions), respectively, and correlated with clinical outcomes. RESULTS: Cavitations of pulmonary lesions were seen in nine (2%) patients at baseline, and 97 (19%) during treatment. The use of mRECIST resulted in an alteration of the response category. For patients with post-therapy cavitation, the objective response rate was 56% using RECIST1.1 and 67% by mRECIST. In addition, the survival rates between partial response, stable disease, and progressive disease when the mRECIST was applied were significantly different (p < 0.05), while RECIST1.1 failed to show survival differences (p = 0.218). CONCLUSION: For patients with post-therapy cavitation, mRECIST exhibited higher predictability of survival than RECIST1.1. Response assessment might be improved by incorporating cavitation into assessment, potentially altering outcomes of key clinical efficacy parameters.

TFAB002s, novel CD20-targeting T cell-dependent bispecific Fab-FabCH3 antibodies, exhibit potent antitumor efficacy against malignant B-cell lymphoma.

B-cell lymphoma, clinically, comprises a heterogeneous group of malignancies that encompass various subtypes. CD20 is an optimal target for therapeutic antibodies in B-cell lymphoma immunotherapy since approximately 90% of B-cell malignancies typically exhibit CD20 expression on their surface, while its presence is limited in normal tissues. In this study, we have developed a series of novel non-IgG-like T cell-dependent bispecific antibodies by constructing Fab-FabCH3, referred to as Tandem Antigen-binding Fragment 002 (TFAB002), which specifically target CD20 for the treatment of malignant B-cell lymphoma. TFAB002s display strong binding affinity with CD20 and moderate binding affinity with CD3, thereby triggering target-specific T-cell activation, cytokine release, and tumor cell lysis in vitro. Furthermore, TFAB002s exhibit potent cytotoxicity against B-cell malignancies that express varying levels of CD20. Besides, the TFAB002s show potent pharmacodynamic activity in vivo in the WIL2-S cells CDX mouse model. Collectively, these results underscore the potential of TFAB002s as a highly promising therapeutic approach for selectively depleting CD20-positive B cells, thereby warranting further clinical evaluation as a viable treatment option for CD20-expressing B-cell malignancies.

Outcome benefits of bevacizumab biosimilar (SIBP04) combined with carboplatin and paclitaxel in advanced non-squamous non-small-cell lung cancer patients with EGFR mutation: subgroup analysis of a prospective, randomized phase III clinical trial.

PURPOSE: SIBP04 is a bevacizumab biosimilar, and bevacizumab combined with carboplatin and paclitaxel in advanced non-squamous non-small-cell lung cancer (nsqNSCLC) has been recommended as the first-line treatment choice. However, the efforts of bevacizumab combined with carboplatin and paclitaxel for nsqNSCLC patients with EGFR mutation remained unclear. Here we report an EGFR mutation subgroup analysis of a prospective, randomized phase III clinical trial (NCT05318443). METHODS: In this randomized, double-blind, multi-center, parallel controlled, phase III clinical trial, locally advanced, metastatic NSCLC patients were enrolled, and EGFR expression was examined and considered as a stratification factor. All patients received 4 to 6 cycles of paclitaxel and carboplatin plus SIBP04 or bevacizumab 15 mg/kg intravenously followed by SIBP04 15 mg/kg maintenance until intolerable toxicity, disease progression or death. Patients with EGFR mutation and wild-type were assessed for progression-free survival (PFS) and overall survival (OS). RESULTS: EGFR expression was examined in 398 NSCLC patients (142 with EGFR mutation, 256 with EGFR wild type). PFS in EGFR mutation patients was significantly longer than EGFR wild-type patients (10.91 vs. 7.82 months; HR = 0.692, 95% CI 0.519-0.921, P = 0.011). The median OS in patients with EGFR mutation was not reached while that of EGFR wild-type group was 17.54 months (HR = 0.398, 95% CI 0.275-0.575, P < 0.001). However, there were no significant differences in objective response rate (61.97% vs. 55.86%, P = 0.237) or disease control rate (90.14% vs. 89.84%, P = 0.925). CONCLUSION: Bevacizumab combined with chemotherapy significantly prolonged the PFS and OS of advanced nsqNSCLC patients with EGFR mutation.

Neutralization mechanism of a human antibody with pan-coronavirus reactivity including SARS-CoV-2.

Frequent outbreaks of coronaviruses underscore the need for antivirals and vaccines that can counter a broad range of coronavirus types. We isolated a human antibody named 76E1 from a COVID-19 convalescent patient, and report that it has broad-range neutralizing activity against multiple α- and ß-coronaviruses, including the SARS-CoV-2 variants. 76E1 also binds its epitope in peptides from γ- and δ-coronaviruses. 76E1 cross-protects against SARS-CoV-2 and HCoV-OC43 infection in both prophylactic and therapeutic murine animal models. Structural and functional studies revealed that 76E1 targets a unique epitope within the spike protein that comprises the highly conserved S2' site and the fusion peptide. The epitope that 76E1 binds is partially buried in the structure of the SARS-CoV-2 spike trimer in the prefusion state, but is exposed when the spike protein binds to ACE2. This observation suggests that 76E1 binds to the epitope at an intermediate state of the spike trimer during the transition from the prefusion to the postfusion state, thereby blocking membrane fusion and viral entry. We hope that the identification of this crucial epitope, which can be recognized by 76E1, will guide epitope-based design of next-generation pan-coronavirus vaccines and antivirals.

Comprehensive mapping of binding hot spots of SARS-CoV-2 RBD-specific neutralizing antibodies for tracking immune escape variants.

BACKGROUND: The receptor-binding domain (RBD) variants of SARS-CoV-2 could impair antibody-mediated neutralization of the virus by host immunity; thus, prospective surveillance of antibody escape mutants and understanding the evolution of RBD are urgently needed. METHODS: Using the single B cell cloning technology, we isolated and characterized 93 RBD-specific antibodies from the memory B cells of four COVID-19 convalescent individuals in the early stage of the pandemic. Then, global RBD alanine scanning with a panel of 19 selected neutralizing antibodies (NAbs), including several broadly reactive NAbs, was performed. Furthermore, we assessed the impact of single natural mutation or co-mutations of concern at key positions of RBD on the neutralization escape and ACE2 binding function by recombinant proteins and pseudoviruses. RESULTS: Thirty-three amino acid positions within four independent antigenic sites (1 to 4) of RBD were identified as valuable indicators of antigenic changes in the RBD. The comprehensive escape mutation map not only confirms the widely circulating strains carrying important immune escape RBD mutations such as K417N, E484K, and L452R, but also facilitates the discovery of new immune escape-enabling mutations such as F486L, N450K, F490S, and R346S. Of note, these escape mutations could not affect the ACE2 binding affinity of RBD, among which L452R even enhanced binding. Furthermore, we showed that RBD co-mutations K417N, E484K, and N501Y present in B.1.351 appear more resistant to NAbs and human convalescent plasma from the early stage of the pandemic, possibly due to an additive effect. Conversely, double mutations E484Q and L452R present in B.1.617.1 variant show partial antibody evasion with no evidence for an additive effect. CONCLUSIONS: Our study provides a global view of the determinants for neutralizing antibody recognition, antigenic conservation, and RBD conformation. The in-depth escape maps may have value for prospective surveillance of SARS-CoV-2 immune escape variants. Special attention should be paid to the accumulation of co-mutations at distinct major antigenic sites. Finally, the new broadly reactive NAbs described here represent new potential opportunities for the prevention and treatment of COVID-19.

Key residues of the receptor binding motif in the spike protein of SARS-CoV-2 that interact with ACE2 and neutralizing antibodies.

Coronavirus disease 2019 (COVID-19), caused by the novel human coronavirus SARS-CoV-2, is currently a major threat to public health worldwide. The viral spike protein binds the host receptor angiotensin-converting enzyme 2 (ACE2) via the receptor-binding domain (RBD), and thus is believed to be a major target to block viral entry. Both SARS-CoV-2 and SARS-CoV share this mechanism. Here we functionally analyzed the key amino acid residues located within receptor binding motif of RBD that may interact with human ACE2 and available neutralizing antibodies. The in vivo experiments showed that immunization with either the SARS-CoV RBD or SARS-CoV-2 RBD was able to induce strong clade-specific neutralizing antibodies in mice; however, the cross-neutralizing activity was much weaker, indicating that there are distinct antigenic features in the RBDs of the two viruses. This finding was confirmed with the available neutralizing monoclonal antibodies against SARS-CoV or SARS-CoV-2. It is worth noting that a newly developed SARS-CoV-2 human antibody, HA001, was able to neutralize SARS-CoV-2, but failed to recognize SARS-CoV. Moreover, the potential epitope residues of HA001 were identified as A475 and F486 in the SARS-CoV-2 RBD, representing new binding sites for neutralizing antibodies. Overall, our study has revealed the presence of different key epitopes between SARS-CoV and SARS-CoV-2, which indicates the necessity to develop new prophylactic vaccine and antibody drugs for specific control of the COVID-19 pandemic although the available agents obtained from the SARS-CoV study are unneglectable.