BPX-701: TCR Product Candidate Entering Clinic in AML & MDS

We have begun dosing patients in a Phase 1 clinical trial, BP-011, with our high-affinity T cell receptor (TCR) BPX-701. The drug candidate incorporates the CaspaCIDe® safety switch and is designed to target malignant cells expressing the preferentially-expressed antigen in melanoma, or PRAME. Initial planned indications include refractory or relapsed acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), with an additional study planned for metastatic uveal melanoma.

While adoptive T cell therapies, such as TCR therapy, have yielded high objective response rates in blood cancers, serious and sometimes fatal side effects have arisen as a result of the treatment. In solid tumors, the behavior of TCR therapy is even more unpredictable. We believe that our safety switch technology can address these concerns by enabling physicians to activate cell death in the donor T cells should they become toxic.

In preclinical studies, PRAME-specific clones showed high reactivity against a panel of PRAME positive tumor cell lines, metastatic melanoma, sarcomas and neuroblastoma tissues, and no reactivity against normal cell types, with the exception of low reactivity against kidney epithelial cells and intermediate reactivity against mature dendritic cells. In vitro study data showed that BPX-701 demonstrated strong affinity to panels of cancer cells presenting PRAME peptides and low affinity to non-tumor cells, as well as complete elimination of BPX-701 cells in response to rimiducid.