The ranked field for this dataset covers 100 assignees, with the leader holding 4,200 records and the top 5 combined holding 6,413 records, 25.0% of all 25,655 records in scope. Beyond the top 10 — which together hold 31.6% of records — the field thins quickly into a long tail of companies and institutions filing in the single digits to low hundreds. That combination of a short leader group and a wide open tail means a well-drafted new entrant is not automatically boxed out by incumbents.

Filing volume peaked in 2020 at 1,487 records and the last fully comparable years show a genuine decline, from 1,480 records in 2021 to 567 in 2024 — a 62% drop. However, publication lags filing by roughly 18 months, so 2025 and 2026 figures are necessarily incomplete and should not be read as continuing that decline. The honest read is that the field cooled from its 2020 high through 2024; anything after that is still filling in.

A61K (medicinal preparations) is the most common class, appearing on 65.5% of the 25,655 records in scope, followed by C07K (peptides & proteins) at 41.6% and A61P (therapeutic activity of compounds) at 33.1%. C12N (microorganisms & genetic engineering) covers 27.5% of records, with G01N, C12Q, C07D and C07H each appearing on well under 12%. Because records often carry several IPC codes, these percentages sum to more than 100% and should not be treated as mutually exclusive shares of the field.

US20240229143A1, filed by Iogenetics and published 2024-07-11, covers methods for maximising immune response to mutated tumour-specific proteins through dendritic cell or T-cell stimulation in vitro, or through administration of a neoantigen vaccine built from peptides or nucleic acids designed for binding affinity to a specific patient's MHC alleles. It sits downstream of the checkpoint-binding filings that dominate the most-cited list in this corpus, so it is more likely to constrain patient-specific neoantigen design work than general checkpoint-blockade approaches. Anyone working on MHC-affinity-tuned peptide design for cancer immunotherapy should read its claims in full rather than relying on the abstract.

The dense claim territory sits on A61K formulation language stacked with C07K protein/peptide composition claims and PD-1/PD-L1 binding — that is where most citation weight and filing volume concentrate. Adjacent branches such as patient-specific MHC-binding assays, non-viral delivery carriers for peptide vaccines, and combination checkpoint-plus-cell-response biomarker claims show comparatively thin density by comparison. A first claim in one of those branches has more room to be drafted broadly before running into prior art.