Peptide-drug conjugates (PDCs) have emerged as a promising modality in precision oncology, enabling targeted delivery of cytotoxic payloads while minimizing off-target toxicity. The integration of covalent warheads, such as those based on sulfur(VI) fluoride exchange (SuFEx) chemistry, enhances drug-target residence time and tumor accumulation. However, existing screening methods for covalent peptide (CP) libraries require post-translational warhead conjugation, limiting throughput. Here, we present an integrated mRNA display platform that incorporates covalent warheads during ribosomal synthesis, enabling efficient screening of ultra-diverse covalent macrocyclic peptide libraries (>10¹³ variants). This approach, using site-specific incorporation of N-chloroacetyl-d-phenylalanine and fluorosulfate-l-tyrosine, accelerated the discovery of irreversibly binding (K _i = 3.58 μmol/L) Nectin-4-targeting peptide CP-N1-N₃ via proximity-triggered SuFEx. The peptide was further conjugated to cytotoxic payloads, yielding the covalent PDC CP-N1-MMAE with potent cytotoxicity (IC₅₀ ≈ 43 nmol/L) against MDA-MB-468 cells. This platform establishes a new paradigm for precision covalent drug discovery.

Objective:To summarize the clinical features, treatments and prognoses of aggressive natural killer cell leukemia (ANKL) in children.Methods:Clinical data and follow-up results were retrospectively reviewed for one hospitalized case of ANKL in June 2019.Through a literature search, the relevant items were retrieved from the databases of China National Knowledge Infrastructure, WanFang and PubMed using the Chinese and English keywords of "aggressive natural killer cell leukemia" and "children" up to December 2021.Results:This 8-year-old girl was diagnosed with ANKL by flow cytometric immunophenotype and immunohistochemical stain.Fever was the initial manifestation accompanied by sallow complexion, fatigue, enlargement of liver, spleen and lymph node and hematopenia of three lines.Allogeneic hematopoietic stem cell transplantation (allo-HSCT) was performed after chemotherapy.As of April 2022, the child stayed in a disease-free survival state after follow-ups for over 2 years.The literature search finally yielded 7 eligible Chinese and 10 English reports with a total of 17 pediatric ANKLs.In this group, there were fever (n=15), rash (n=1), perineal mass (n=1) and diarrhea, vomiting and other digestive tract symptoms (n=1). Six cases were misdiagnosed during an early stage of disease.4 cases received chemotherapy alone, 3 cases received chemotherapy regimen for acute lymphoblastic leukemia, 1 child died and one death occurred after received chemotherapy regimen of "cisplatin + vincristine + doxorubicin + ifosfamide". Allo-HSCT was performed in 5 patients after remission with chemotherapy and one child died from multiple organ failure at 9 months after allo-HSCT.Nine cases gave up treatment.Conclusions:ANKL has a rapid disease progression, diverse clinical manifestations, easy misdiagnosis and poor prognosis.For suspected ANKL cases, clinicians perform multiple bone perforations at multiple sites and immunophenotype by flow cytometry as soon as possible to confirm the diagnosis.Currently allo-HSCT offers a long-term survival of ANKL patients.