Trastuzumab immunogenicity development in patients' sera and in laboratory animals

Pulmonary Pharmacokinetics of Antibody and Antibody Fragments Following Systemic and Local Administration in Mice

Objective: This study aimed to investigate the effect of molecular size on the pulmonary pharmacokinetics (PK) of proteins following systemic and local administration in wild-type mice. Methods: A non-cross-reactive antibody trastuzumab, and F(ab')2, Fab, and scFv fragments of this antibody were used for the investigation. Proteins were injected intravenously or via intratracheal instillation, and PK was measured in plasma, lungs, trachea, bronchi, and bronchoalveolar lavage (BAL) using ELISA. Concentrations in BAL were urea normalized. Results: Following systemic administration, the biodistribution coefficient (BC) for lungs, trachea, bronchi, and BAL was 11%, 11%, 15%, and 2% for the antibody; 15%, 7%, 13%, and 8% for F(ab')2; 25%, 17%, 28%, and 46% for Fab; and 14%, 1%, 2%, and 50% for scFv. The antibody exposure in BAL was ~50-fold lower than plasma and ~5-7-fold lower than lung tissues. A tissue-dependent BC vs. molecular size relationship was observed, where distribution in tissues was the highest for Fab (50 kDa), and scFv demonstrated the highest distribution in the BAL. PK data generated following local administration were quite variable; however, local dosing resulted in BAL exposures that were 10-100-fold higher than those achieved after systemic dosing for all proteins. The BAL antibody concentrations were 100-1000-fold higher than plasma concentrations initially, which normalized by day 14. For most proteins, local dosing resulted in higher lung concentrations than trachea and bronchi, opposite to what was observed after systemic dosing. Conclusions: The PK data presented here provide an unprecedented quantitative insight into the effect of molecular size on the pulmonary disposition of proteins following systemic and local administration.

Safety profile of trastuzumab originator vs biosimilars: a systematic review and meta-analysis of randomized clinical trials

PURPOSE

In the last decade trastuzumab biosimilars became more and more frequent. Among their uses, from several years, they have been available in Europe for the treatment of HER2-positive metastatic breast cancer, as an alternative to Herceptin®.

METHODS/PATIENTS

This meta-analysis aimed to analyze the available literature with particular focus on phase 3 randomized clinical trials (RCTs) comparing adverse events between trastuzumab biosimilar and originator. A systematic review was conducted in Pubmed and Scopus to include all phase 3 RCTs related to trastuzumab in patients with HER2-positive breast cancer and published up to July 31, 2023. Of the 508 records identified, 14 articles were meta-analyzed for safety information, including serious treatment emergent adverse events, death-related adverse events, neutropenia, leukopenia, infections, increased ALT, increased AST, anti-drug antibody, and neutralizing antibody.

RESULTS

Included patients had an early breast cancer (N=2,877) or a metastatic breast cancer (N=2,603). No significant difference in death-related adverse events was found for trastuzumab biosimilar and originator when evaluated for an early breast cancer in the neoadjuvant phase (Risk Ratio [RR], 1.30; 95% confidence interval [CI], 0.47-3.59; I2 = 0%; p = 0.57) and overall (RR, 0.43; 95%CI, 0.11-1.66; I2 = 20%; p = 0.26), and for metastatic breast cancer (RR, 0.61; 95%CI, 0.30-1.26; I2 = 0%; p = 0.85).

CONCLUSIONS

No difference was also observed for all other safety outcomes as in accordance with clinical studies necessary for the registration and approval of a biosimilar at a European level.

Bone-Specific Enhancement of Antibody Therapy for Breast Cancer Metastasis to Bone

Despite the rapid evolution of therapeutic antibodies, their clinical efficacy in the treatment of bone tumors is hampered due to the inadequate pharmacokinetics and poor bone tissue accessibility of these large macromolecules. Here, we show that engineering therapeutic antibodies with bone-homing peptide sequences dramatically enhances their concentrations in the bone metastatic niche, resulting in significantly reduced survival and progression of breast cancer bone metastases. To enhance the bone tumor-targeting ability of engineered antibodies, we introduced varying numbers of bone-homing peptides into permissive sites of the anti-HER2 antibody, trastuzumab. Compared to the unmodified antibody, the engineered antibodies have similar pharmacokinetics and in vitro cytotoxic activity, but exhibit improved bone tumor distribution in vivo. Accordingly, in xenograft models of breast cancer metastasis to bone sites, engineered antibodies with enhanced bone specificity exhibit increased inhibition of both initial bone metastases and secondary multiorgan metastases. Furthermore, this engineering strategy is also applied to prepare bone-targeting antibody-drug conjugates with enhanced therapeutic efficacy. These results demonstrate that adding bone-specific targeting to antibody therapy results in robust bone tumor delivery efficacy. This provides a powerful strategy to overcome the poor accessibility of antibodies to the bone tumors and the consequential resistance to the therapy.

Tetravalent SARS-CoV-2 Neutralizing Antibodies Show Enhanced Potency and Resistance to Escape Mutations

Neutralizing antibodies (nAbs) hold promise as therapeutics against COVID-19. Here, we describe protein engineering and modular design principles that have led to the development of synthetic bivalent and tetravalent nAbs against SARS-CoV-2. The best nAb targets the host receptor binding site of the viral S-protein and tetravalent versions block entry with a potency exceeding bivalent nAbs by an order of magnitude. Structural studies show that both the bivalent and tetravalent nAbs can make multivalent interactions with a single S-protein trimer, consistent with the avidity and potency of these molecules. Significantly, we show that the tetravalent nAbs show increased tolerance to potential virus escape mutants and an emerging variant of concern. Bivalent and tetravalent nAbs can be produced at large-scale and are as stable and specific as approved antibody drugs. Our results provide a general framework for enhancing antiviral therapies against COVID-19 and related viral threats, and our strategy can be applied to virtually any antibody drug.