AJICAP-M: Traceless Affinity Peptide Mediated Conjugation Technology for Site-Selective Antibody-Drug Conjugate Synthesis

A traceless site-selective conjugation method, "AJICAP-M", was developed for native antibodies at sites using Fc-affinity peptides, focusing on Lys248 or Lys288. It produces antibody-drug conjugates (ADCs) with consistent drug-to-antibody ratios, enhanced stability, and simplified manufacturing. Comparative in vivo assessment demonstrated AJICAP-M's superior stability over traditional ADCs. This technology has been successfully applied to continuous-flow manufacturing, marking the first achievement in site-selective ADC production. This manuscript outlines AJICAP-M's methodology and its effectiveness in ADC production.

AJICAP Second Generation: Improved Chemical Site-Specific Conjugation Technology for Antibody-Drug Conjugate Production

The site-directed chemical conjugation of antibodies remains an area of great interest and active efforts within the antibody-drug conjugate (ADC) community. We previously reported a unique site modification using a class of immunoglobulin-G (IgG) Fc-affinity reagents to establish a versatile, streamlined, and site-selective conjugation of native antibodies to enhance the therapeutic index of the resultant ADCs. This methodology, termed "AJICAP", successfully modified Lys248 of native antibodies to produce site-specific ADC with a wider therapeutic index than the Food and Drug Administration-approved ADC, Kadcyla. However, the long reaction sequences, including the reduction-oxidation (redox) treatment, increased the aggregation level. In this manuscript, we aimed to present an updated Fc-affinity-mediated site-specific conjugation technology named "AJICAP second generation" without redox treatment utilizing a "one-pot" antibody modification reaction. The stability of Fc affinity reagents was improved owing to structural optimization, enabling the production of various ADCs without aggregation. In addition to Lys248 conjugation, Lys288 conjugated ADCs with homogeneous drug-to-antibody ratio of 2 were produced using different Fc affinity peptide reagent possessing a proper spacer linkage. These two conjugation technologies were used to produce over 20 ADCs from several combinations of antibodies and drug linkers. The in vivo profile of Lys248 and Lys288 conjugated ADCs was also compared. Furthermore, nontraditional ADC production, such as antibody-protein conjugates and antibody-oligonucleotide conjugates, were achieved. These results strongly indicate that this Fc affinity conjugation approach is a promising strategy for manufacturing site-specific antibody conjugates without antibody engineering.

[A case of metastatic ureteral tumor]

We report a case of metastatic ureteral tumor resulting from gastric cancer in a 56-year-old female. She had undergone distal gastrectomy for gastric cancer in our hospital 3 years earlier, on the histological diagnosis of poorly differentiated adenocarcinoma with absolute curative resection. In March, 1987, she visited our hospital complaining of microscopic hematuria and lumbago. Intravenous pyelography and left retrograde pyelography revealed the stenotic change of the left ureter and hydronephrosis. Endoscopic ureteral biopsy was performed, and the histological diagnosis was an inflammatory change of the ureter. But the hydronephrosis increased, so partial ureterectomy was performed. The histological examination confirmed adenocarcinoma in the left ureter resulting from gastric cancer. From the 340th postoperative day, she complained of general fatigue and vomiting, and gastroscopy revealed recurrent gastric cancer.