⁹⁹mTc-HYNIC-MPG: a novel SPECT probe for targeting mutated EGFR

Targeting oncogenic kinases: Insights on FDA approved tyrosine kinase inhibitors

Protein kinases play pivotal roles in various biological functions, influencing cell differentiation, promoting survival, and regulating the cell cycle. The disruption of protein kinase activity is intricately linked to pathways in tumor development. This manuscript explores the transformative impact of protein kinase inhibitors on cancer therapy, particularly their efficacy in cases driven by targeted mutations. Focusing on key tyrosine kinase inhibitors (TKIs) like Bcr-Abl, Epidermal Growth Factor Receptor (EGFR), and Vascular Endothelial Growth Factor Receptor (VEGFR), it targets critical kinase families in cancer progression. Clinical trial details of these TKIs offer insights into their therapeutic potentials. Learning from FDA-approved kinase inhibitors, the review dissects trends in kinase drug development since imatinib's paradigm-shifting approval in 2001. TKIs have evolved into pivotal drugs, extending beyond oncology. Ongoing clinical trials explore novel kinase targets, revealing the vast potential within the human kinome. The manuscript provides a detailed analysis of advancements until 2022, discussing the roles of specific oncogenic protein kinases in cancer development and carcinogenesis. Our exploration on PubMed for relevant and significant TKIs undergoing pre-FDA approval phase III clinical trials enriches the discussion with valuable findings. While kinase inhibitors exhibit lower toxicity than traditional chemotherapy in cancer treatment, challenges like resistance and side effects emphasize the necessity of understanding resistance mechanisms, prompting the development of novel inhibitors like osimertinib targeting specific mutant proteins. The review advocates thorough research on effective combination therapies, highlighting the future development of more selective RTKIs to optimize patient-specific cancer treatment and reduce adverse events.

Design, synthesis and biological evaluation of small molecule fluorescent probes targeting EGFR for tumor detection and treatment

The epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor that plays a crucial role in cell differentiation and tumor progression, and its overexpression is closely associated with the development and metastasis of multiple cancers. The development of a fluorescent probe capable of targeting EGFR while simultaneously integrating diagnostic and therapeutic functions could have a profound impact on the treatment of related cancers. In this study, we developed a series of EGFR-targeting probes that consisted of an environment-sensitive 1,8-naphthalimide fluorophore, a linker unit and a targeting unit (gefitinib), using a coupling strategy. The synthesized probes were first evaluated for their spectroscopic properties and cytotoxicities against different cell lines, which were selected based on their intrinsic EGFR expression levels. Remarkably, among the probes tested, GP1 showed outstanding environmental sensitivity and exhibited a specific response to tumor cells that overexpress EGFR. Furthermore, the representative probe GP1 was evaluated for its EGFR-specific targeting ability in live-cell fluorescence imaging and in vivo xenograft imaging, as well as its in vivo anti-tumor activity. The results showed that the probe GP1 had excellent EGFR-specific targeting ability, exhibited competitive replacement behavior towards the EGFR inhibitor gefitinib, and demonstrated potent anti-tumor effects in a CT-26 tumor-bearing mouse model. Overall, as a turn-on EGFR targeting fluorescent ligand, GP1 holds immense promise as a valuable tool for tumor detection and treatment.

Evaluation of 99mTc-HYNIC-MPG as a novel SPECT radiotracer to detect EGFR-activating mutations in NSCLC

Tyrosine kinase inhibitors (EGFR-TKIs) targeting the epidermal growth factor receptor (EGFR) have been used in non-small cell lung carcinoma (NSCLC) for years with promising results, in particular in patients with activating mutations in the EGFR kinase domain (exon 19 E746-A750 deletion or exon 21 L858R point mutation). However, despite their great success in the clinic, a significant number of patients do not respond to EGFR-TKIs, such as those carrying the L858R/T790M mutation or EGFR wild type. Thus, detecting the EGFR mutation status before EGFR-TKIs therapy is essential to ensure its efficacy. In this study, we report a novel SPECT tracer 99mTc-HYNIC-MPG that binds specifically to activating mutant EGFR and which could therefore be used to noninvasively select patients sensitive to EGFR-TKIs. We evaluated the capacity of 99mTc-HYNIC-MPG in detecting EGFR-activating mutations both in vitro and in vivo using four human NSCLC cell lines (PC9, H1975, H358 and H520). 99mTc-HYNIC-MPG had significantly higher accumulation in PC9 tumor cells when compared to H1975, H358 and H520 tumors cells, which may be due to the activating mutations (exon 19 deletion) in EGFR tyrosine kinase domain in PC9 cells. Thus, 99mTc-HYNIC-MPG SPECT imaging may be used to identify NSCLC tumors with a potential high response rate to EGFR-TKIs.