Many immunotherapy papers introduce Antibody-Drug Conjugates (ADCs) as an emerging modality of immunotherapy, and the following is one example:
Marin-Acevedo, Julian A et al. “Cancer immunotherapy beyond immune checkpoint inhibitors.” Journal of hematology & oncology vol. 11,1 8. 12 Jan. 2018, DOI: 10.1186/s13045-017-0552-6
However, I find it difficult to understand why ADCs are regarded as 'immunotherapy'. If cancer-killing effect is achieved by the cytotoxin (payload) in ADC, isn't it just a targeted therapy (small-molecule therapy like Sunitinib or Sorafenib) with elaborate carriers?
Or, does the antibody part in ADC actually have therapeutic effects as well? Are they more than just carriers? If so, are there any papers which discuss this? I do not have a biology or immunology background so I may be missing a lot in terms of immunological mechanisms, I'd appreciate any insights or opinions.