GPC-100, a novel CXCR4 antagonist, improves in vivo hematopoietic cell mobilization when combined with propranolol

Autologous Stem Cell Transplant (ASCT) is increasingly used to treat hematological malignancies. A key requisite for ASCT is mobilization of hematopoietic stem cells into peripheral blood, where they are collected by apheresis and stored for later transplantation. However, success is often hindered by poor mobilization due to factors including prior treatments. The combination of G-CSF and GPC-100, a small molecule antagonist of CXCR4, showed potential in a multiple myeloma clinical trial for sufficient and rapid collection of CD34+ stem cells, compared to the historical results from the standards of care, G-CSF alone or G-CSF with plerixafor, also a CXCR4 antagonist. In the present study, we show that GPC-100 has high affinity towards the chemokine receptor CXCR4, and it potently inhibits B-arrestin recruitment, calcium flux and cell migration mediated by its ligand CXCL12. Proximity Ligation Assay revealed that in native cell systems with endogenous receptor expressions, CXCR4 co-localizes with the beta-2 adrenergic receptor (B2AR). Co-treatment with CXCL12 and the B2AR agonist epinephrine synergistically increase B-arrestin recruitment to CXCR4 and calcium flux. This increase is blocked by the co-treatment with GPC-100 and propranolol, a non-selective beta-adrenergic blocker, indicating a functional synergy. In mice, GPC-100 mobilized more white blood cells into peripheral blood compared to plerixafor. GPC-100 induced mobilization was further amplified by propranolol pretreatment and was comparable to mobilization by G-CSF. Addition of propranolol to the G-CSF and GPC-100 combination resulted in greater stem cell mobilization than the G-CSF and plerixafor combination. Together, our studies suggest that the combination of GPC-100 and propranolol is a novel strategy for stem cell mobilization and support the current clinical trial in multiple myeloma registered as NCT05561751 at www.clinicaltrials.gov.

PLOS One DOI: 10.1371/journal.pone.0287863

自体造血干细胞移植（Autologous Stem Cell Transplant, ASCT）正日益广泛地应用于血液系统恶性肿瘤的治疗。ASCT的核心环节是将造血干细胞动员至外周血，随后通过单采术采集并储存，以供后续移植使用。然而，包括既往治疗在内的多种因素常导致动员效果不佳，进而阻碍移植成功。与标准治疗方案（单用粒细胞集落刺激因子（Granulocyte Colony-Stimulating Factor, G-CSF）或G-CSF联合C-X-C趋化因子受体4（CXCR4）拮抗剂普乐沙福（plerixafor））的既往研究结果相比，G-CSF联合GPC-100（一种CXCR4小分子拮抗剂）的方案在多发性骨髓瘤（multiple myeloma）临床试验中展现出可高效、快速采集CD34阳性干细胞的潜力。
本研究证实，GPC-100对C-X-C趋化因子受体4（CXCR4）具有高亲和力，可有效抑制其配体CXCL12介导的β抑制蛋白招募、钙流反应及细胞迁移。邻近连接分析法（Proximity Ligation Assay, PLA）结果显示，在内源性受体表达的天然细胞系统中，CXCR4与β2肾上腺素能受体（β2AR）存在共定位现象。CXCL12与β2AR激动剂肾上腺素联合处理可协同增强CXCR4介导的β抑制蛋白招募与钙流反应，而该协同效应可被GPC-100与非选择性β肾上腺素能阻断剂普萘洛尔（propranolol）联合处理阻断，提示二者存在功能协同作用。
在小鼠模型中，与普乐沙福相比，GPC-100可动员更多白细胞进入外周血。普萘洛尔预处理可进一步增强GPC-100诱导的动员效果，且该效果与粒细胞集落刺激因子（G-CSF）介导的动员水平相当。将普萘洛尔加入G-CSF与GPC-100联合方案后，其干细胞动员效果优于G-CSF联合普乐沙福方案。
综上，本研究表明GPC-100联合普萘洛尔是一种新型干细胞动员策略，并为当前注册于www.clinicaltrials.gov、编号为NCT05561751的多发性骨髓瘤临床试验提供了实验依据。
《公共科学图书馆·综合》（PLOS One）DOI：10.1371/journal.pone.0287863