BiVictriX Therapeutics plc announced positive in vivo data from a toxicity evaluation study with BVX001, BiVictriX's lead programme, compared to gemtuzumab ozogamicin (GO). GO, marketed as Mylotarg™, is the only approved antibody drug conjugate (ADC) indicated for the treatment of acute myeloid leukaemia (AML).One of the significant toxicities of GO is the reduction in normal neutrophil counts in patients with AML. Neutrophils are a form of immune cell and a reduction in the number of these cells heightens the risk of developing potential fatal severe infections and sepsis, a major concern in patients with AML.

BVX001 was reported to be well-tolerated and showed a highly favorable safety profile across two doses of BVX001 (0.3 mg/kg and 3 mg/kg), compared with the reported maximum tolerated dose of GO1 (0.3 mg/kg) in a CD34-boosted humanised murine model. The results showed that: The proportion of healthy human CD33+ myeloid cells in the bone marrow was significantly lower with GO compared to BVX001 at both an equivalent dose to GO (0.3mg/kg) and a 10-fold higher dose (3mg/kg), at seven- and fourteen-days post-injection. The total number of healthy neutrophils and total healthy leukocytes, types of specialised immune cells, were significantly lower with GO compared to the equivalent dose of BVX001, at fourteen days post-injection.

The total number of healthy human CD33+ cells was significantly lower with GO compared to the vehicle control seven days post-injection. These results model commonly reported toxicities of GO in clinical practice. Other observed effects with GO included a non-statistical lower level of healthy early bone marrow progenitor cells at day fourteen post injection, compared to both doses of BVX001.

A non-statistical higher proportion of CD7+ cells among CD3+ T cells in blood at day three post injection was reported with GO, compared to BVX001 and the control vehicle. This announcement follows the identification of a development lead for BiVictriX's BVX001 programme asannounced on 7 December 2022, together with the Company's previously shared in vivo efficacy data for this programme. The Company is now focused on delivering additional in vivo efficacy data to further strengthen the preclinical data package for BVX001, as the Company looks to progress this molecule towards the clinic.

The results from this in vivo toxicity evaluation study will be submitted for publication and will be presented at an upcoming scientific conference.