You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Immunogenicity assays for antibody-drug conjugates: case study with ado-trastuzumab emtansine. Background: Antibody-drug conjugates (ADCs) such as Kadcyla™ (ado-trastuzumab emtansine [T-DM1]) present covalently bound cytotoxic drugs, which may influence their immunogenicity potential compared with antibody therapies. Therefore, ADCs require assay strategies that allow measurement of responses to all the molecular components. Results: The immunogenicity strategy for T-DM1 used a risk-based, tiered approach that included screening and titration to detect antitherapeutic antibodies; confirmation of positive responses; and characterization to assess whether the immune response is primarily to the antibody or to the linker-drug and/or new epitopes in trastuzumab resulting from conjugation. Conclusion: The tiered immunogenicity assay strategy for T-DM1 allowed detection of antitherapeutic antibodies to all components of the ADC in multiple nonclinical and clinical studies. Characterization strategies implemented in clinical studies provided additional insights into the specificity of the immune response.
{"Chemical": ["DM1"]}