PRL3-zumab, a first-in-class humanized antibody for cancer therapy.

Novel, tumor-specific drugs are urgently needed for a breakthrough in cancer therapy. Herein, we generated a first-in-class humanized antibody (PRL3-zumab) against PRL-3, an intracellular tumor-associated phosphatase upregulated in multiple human cancers, for unconventional cancer immunotherapies. We focused on gastric cancer (GC), wherein elevated PRL-3 mRNA levels significantly correlated with shortened overall survival of GC patients. PRL-3 protein was overexpressed in 85% of fresh-frozen clinical gastric tumor samples examined but not in patient-matched normal gastric tissues. Using human GC cell lines, we demonstrated that PRL3-zumab specifically blocked PRL-3+, but not PRL-3-, orthotopic gastric tumors. In this setting, PRL3-zumab had better therapeutic efficacy as a monotherapy, rather than simultaneous combination with 5-fluorouracil or 5-fluorouracil alone. PRL3-zumab could also prevent PRL-3+ tumor recurrence. Mechanistically, we found that intracellular PRL-3 antigens could be externalized to become "extracellular oncotargets" that serve as bait for PRL3-zumab binding to potentially bridge and recruit immunocytes into tumor microenvironments for killing effects on cancer cells. In summary, our results document a comprehensive cancer therapeutic approach to specific antibody-targeted therapy against the PRL-3 oncotarget as a case study for developing antibodies against other intracellular targets in drug discovery.

HLA class I expression and its alteration by preoperative hyperthermo-chemoradiotherapy in patients with rectal cancer.

OBJECTIVE: Enhancing immunologic responses, including human leukocyte antigen (HLA) class I expression on tumor cells and recognition and elimination of tumor cells by tumor-specific cytotoxic T lymphocyte (CTL), is considered a novel concept of radiotherapy. The present study examined patients who underwent preoperative hyperthermo-chemoradiotherapy (HCRT) for locally advanced rectal cancer to assess the correlation between HLA class I expression and clinical outcome. MATERIALS AND METHODS: Seventy-eight patients with locally advanced rectal adenocarcinoma who received preoperative HCRT were enrolled. The median age of the patients was 64 years (range, 33-85 years) and 4, 18, and 56 patients had clinical stage I, II and III disease, respectively. Formalin-fixed and paraffin-embedded tissues excised before and after HCRT were subjected to immunohistochemical analysis with an anti-HLA class I-A, B, C antibody. HLA class I expression was graded according to tumor cell positivity. RESULTS: In pre-HCRT, the number of specimens categorized as Grade 0 and 1 were 19 (24%) and 58 (74%), respectively. Only 1 patient (1%) showed Grade 2 expression. However, 6 (8%), 27 (35%), 7 (9%), and 12 (15%) post-HCRT specimens were graded as Grade 0, 1, 2, and 3, respectively. There was a significant increase in HLA class I expression in post-HCRT specimens (p<0.01). However, neither pre- nor post-HCRT HLA class I expression affected overall survival and distant metastasis-free survival in clinical stage III patients. Univariate analysis revealed that Post-HCRT HLA class I expression showed a significant negative relationship with LC (p<0.05). Nevertheless, multivariate analysis showed that there was no correlation between HLA class I expression and clinical outcome. CONCLUSION: HCRT increased HLA class I expression in rectal cancer patients. However, multivariate analysis failed to show any correlation between the level of HLA class I expression and prognosis.