恶性肿瘤的主要治疗仍然是手术切除患病组织。肿瘤边缘是否存在残留病变组织是术后预后和复发的最强预测因子。因此,依靠外科医生在视觉上实时明确区分患病组织和健康组织的能力是至关重要的。近红外-I(NIRI)荧光发射靶向生物分子构建体,如抗癌抗体-荧光团缀合物,即西妥昔单抗-IRDye®800CW(CTB-IRDye®800CW),由于与在标准白光照明(WLI)手术技术或非靶向性荧光团下使用肉眼相比,可以改善肿瘤组织的直接可视化,因此FDA批准用于病变组织的荧光引导切除的临床试验。不幸的是,虽然有用,CTB-IRDye®800CW提供了有限的(i)病变组织的识别和(ii)肿瘤边缘的勾画,因为免疫缀合物由于其光谱/光物理曲线与前/临床设置的固定光学窗口不一致而产生次优的肿瘤背景比(TBR)。因此,CTB-IRDye®800CW与如果TBR由于其他原因而较高相比更倾向于提供不完全切除。为了帮助准确识别深层病变组织,光声(PA)层析成像与CTB-IRDye®800CW一起实施,以实现可导致更高TBR的PA信号。然而,在临床试验实践中,使用IRDye®800CW进行PA成像也会产生低于标准的TBR,因为它提供低PA信号。为了克服这些限制,我们开发了NIRDye812,这是IRDye®800CW的结构修饰拓扑等效物,赋予其产生比等效CTB-缀合物和荧光团IRDye®800CW本身更高的TBR和更好的PA信号的能力,分别。要做到这一点,我们用硫原子取代了内消旋位置的氧原子。CTB-NIRDye812显示出在796nm处的红移吸收波长和在820nm处的峰值NIR-I荧光发射波长,这与商业预/临床NIR-I荧光成像仪器内的预安装固定发射滤光片的固定窗口更好地吻合。总的来说,与体内CTB-IRDye®800CW相比,CTB-NIRDye812的TBR增加了约2倍。此外,NIRDye812显示的PA信号比IRDye®800CW高60%。总的来说,我们实现了我们的目标,即通过对其电子核心进行细微的修饰来改善IRDye®800CW的光谱/光物理和PA特性,从而使其CTB免疫缀合物可能由于其几乎相同的结构而被FDA指定为快速或突破性的指定。显示出大大提高的功效。
The primary treatment for malignant tumors remains to be surgical removal of the diseased tissue. The presence or absence of residual diseased tissue at the tumor margin is the strongest predictor of postoperative prognosis and recurrence. Accordingly, reliance on the ability of surgeons to visually distinguish diseased tissue from healthy tissue unambiguously in real time is crucial. Near infrared-I (NIRI) fluorescence-emitting targeting biomolecular constructs such as anticancer antibody-fluorophore conjugates, namely cetuximab-IRDye® 800CW (CTB-IRDye® 800CW), are FDA-approved for clinical trial usage in the fluorescence-guided resection of diseased tissue due to affording improved direct visualization of tumor tissue when compared to the use of either the unaided eye under standard white light illumination (WLI) surgical techniques or non-targeting fluorophores. Unfortunately, though helpful, CTB-IRDye® 800CW affords limited (i) identification of diseased tissue and (ii) tumor margin delineation, because the
immunoconjugate generates suboptimal tumor-to-background ratios (TBRs) as a result of its spectral/photophysical profiles poorly aligning with the fixed optical windows of pre-/clinical setups. As such, CTB-IRDye® 800CW is more prone to affording incomplete resection compared to if TBRs were higher due to otherwise. To aid in accurately identifying deep-seated diseased tissue, photoacoustic (PA) tomography has been implemented alongside CTB-IRDye® 800CW to achieve PA signals that could result in higher TBRs. However, in clinical trial practice, using IRDye® 800CW for PA imaging also yields subpar TBRs due to it affording low PA signals. To overcome such limitations, we developed NIRDye 812, a structurally-modified topological equivalent of IRDye® 800CW, to confer it the capability to yield both higher TBRs and superior PA signal than that of the equivalent CTB-conjugate and fluorophore IRDye® 800CW itself, respectively. To do so, we substituted the oxygen atom at its meso-position with a sulfur atom. CTB-NIRDye 812 demonstrated a red-shifted absorption wavelength at 796 nm and a peak NIR-I fluorescence emission wavelength at 820 nm, which better dovetails with the fixed windows of preinstalled fixed emission filters within commercial pre-/clinical NIR-I fluorescence imaging instruments. Overall, CTB-NIRDye 812 provided a ∼ 2-fold increase in TBRs compared to those of CTB-IRDye® 800CW in vivo. Also, NIRDye 812 displayed an ∼60% higher PA signal than that of IRDye® 800CW. Collectively, we achieved our goal of improving upon the spectral/photophysical and PA properties of IRDye® 800CW via introducing a subtle modification to its electronic core such that its CTB
immunoconjugate could potentially allow for fast track or breakthrough designation by the FDA due to its near-identical structure displaying considerably improved efficacy.