Highlight

1.ClearMOA

1) The B7H3 protein (encoded from the CD276 gene) is a checkpoint molecule that is highly expressed in solid tumors, with reportedly limited expression in normal tissues. Overexpression of B7H3 is correlated with tumor progression, metastasis, and poor clinical outcome across a variety of malignancies.

2) Monoclonal antibodies targeting B7H3 cause limited toxicity and have demonstrated some anti-tumor activity in clinical trials. Anti-B7H3 ADC can get better anti-tumor effect than anti-B7H3 mAb.

2. Antibodiesspecific binding to human B7H3 protein

Both anti-B7H3 is strong in binding to human B7H3. And anti-B7H3 #2’s affinity to mouse B7H3 is 100-fold weaker than Human B7H3.

3. High selectivity and affinity

1) Both anti-B7H3’s cell-based affinity binding of 1-2 digit nano-molar was observed across cell lines. And No non-specific binding was observed on a target-negative cell line.

2) No non-specific binding to other family members

4. Induced strong B7H3 internalization on tumor cells.

5. Anti-B7H3 ADC showed strong potency in target-expressing cell lines, but weak potency in target-negative cell line, comparable to the isotype control ADC.

6. Good thermostability

Research progress：

1. Anti-B7H3 #2 (MMAE) ADC showed strong potency in target-expressing cell lines. Potency on a target-negative cell line was minimal and comparable to the isotype control ADC.

2. Camptothecin ADCs: DAR8 conjugation was achieved. Both, Anti-B7H3 #1 and #2, showed some differential potency as Camptothecin ADCs over isotype control ADC in Calu-6 and HEC-251 cells.