BeyondSpring Inc. announced data from a poster presentation at the ESMO Congress 2022 being held September 9-13, 2022, in Paris, France. The poster includes a new analysis from the Phase 2/3 PROTECTIVE-1 (NCT03102606) and PROTECTIVE-2 (NCT03294577) trials. The data provides evidence of protection of bone marrow granulocyte-monocyte progenitor (GMP) stem cells within 24 hours after chemotherapy based on an evaluation of peripheral immature and mature neutrophil counts.
Peripheral blood counts for mature (segmented) and immature neutrophils, white blood cells (WBCs), red blood cells (RBCs) and platelets were obtained from LabCorp. The blood counts were analyzed before and 24 hours after chemo administration without (control; N=198) or with plinabulin (N=298). The absolute neutrophil count (ANC) with and without plinabulin was comparable at pre-dose C1D1 (p=0.96) but was significantly higher at 24 hours post-chemo dose with plinabulin vs.
control (p<0.0001). At 24 hours post-chemo dose, the mean ANC had increased by 3.2 x 109/L with plinabulin (p<0.0001) whereas the mean ANC had decreased by 0.55 x 109/L with the control (p=0.018) due to the myelosuppressive effect of TAC chemotherapy. Pre-dose (C1D1), the proportion of patients with a GMP-derived immature cell count value >0 was approximately 0 for both the plinabulin and control arms. At 24 hours post-chemo, the number of patients with an immature neutrophil count >0 had significantly increased with plinabulin but not with the control.
The proportion of patients with immature cells from all other WBCs and RBCs was approximately 0 at pre- or post-chemo dose with or without plinabulin. Plinabulin, BeyondSpring's lead asset, is a selective immunomodulating microtubule-binding agent, which is a potent antigen presenting cell (APC) inducer that is being developed as an anticancer agent. Plinabulin triggers the release of the immune defense protein, GEF-H1, which leads to two distinct effects: first is a durable anti-cancer benefit due to the maturation of dendritic cells resulting in the activation of tumor antigen-specific T-cells to target cancer cells and the second is a CIN prevention benefit.
Plinabulin has single agent anti-cancer activity in a number of cancers including small cell lung cancer (SCLC) and multiple myeloma (MM). Plinabulin also exerts early-onset of action in the prevention of chemotherapy-induced neutropenia (CIN) by boosting the number of hematopoietic stem/progenitor cells (HSPCs).