P2, N=7, Terminated, Northwestern University | Trial completion date: Jul 2030 --> Apr 2026 | Active, not recruiting --> Terminated | Trial primary completion date: May 2026 --> Oct 2025; The study was closed due to accrual.

P2, N=28, Active, not recruiting, National Cancer Institute (NCI) | Recruiting --> Active, not recruiting | N=45 --> 28 | Trial completion date: Jul 2028 --> Jun 2029 | Trial primary completion date: Apr 2028 --> May 2026

P2, N=64, Completed, University of Sydney | Active, not recruiting --> Completed

BRAF inhibitors such as encorafenib are ineffective due to MAPK pathway reactivation driven by BRAF dimerization...dHuR abrogated BRAF expression by inducing its exon 18 skipping, and demonstrated superior suppression of BRAF-mutant CRC tumours including those gaining resistance to BRAF inhibitors. Finally, we performed kinome library CRISPR screening and revealed that inactivation of EGFR or MEK enhanced dHuR cytotoxicity, thus establishing a combinatorial strategy to treat patients with refractory BRAF-mutant CRC.

P2, N=26, Active, not recruiting, University Health Network, Toronto | Trial completion date: Dec 2025 --> Dec 2026 | Trial primary completion date: Dec 2025 --> Dec 2026

P2, N=10, Active, not recruiting, UNICANCER | Trial completion date: Mar 2026 --> Mar 2027

P2, N=7, Active, not recruiting, Northwestern University | Recruiting --> Active, not recruiting | N=43 --> 7 | Trial primary completion date: Jul 2028 --> May 2026

P2, N=86, Active, not recruiting, National Cancer Institute (NCI) | Trial completion date: Sep 2026 --> Jun 2027 | Trial primary completion date: Sep 2026 --> Feb 2026

The cytotoxic effects of three MAPK pathway inhibitors (selumetinib, vemurafenib, dabrafenib) were assessed in ATC cell lines and xenograft models via viability assays and 18F-FDG PET/CT. Furthermore, MAPK pathway inhibitors increased radioiodine uptake in ATC cells. The MAPK pathway inhibitors enhance NIS function through two mechanisms: upregulation of NIS expression and increased ARF4-mediated NIS membrane transport.

Our results highlight that both hypoxia and therapeutic pressure modulate tumor progression in a complex, context-dependent manner.

Notably, δ-TT restored responsiveness to vemurafenib, indicating a synergistic interaction in resistant melanoma cells. Overall, these findings provide mechanistic evidence supporting a potential role for δ-TT as a modulator of drug response and support further investigation of δ-TT-based combination strategies to overcome therapeutic resistance in melanoma.

In contrast, compounds 16, 17, and 22 displayed marked cellular activity despite limited B-RAF inhibition, indicating potential contributions from alternative kinases or yet unidentified off-target mechanisms. The large DSF Tm shifts observed established the poorly exploited pyrimido[4,5-d]pyrimidines as interesting ATP mimetic scaffolds for kinase inhibitor development.