COTI-2

Cells expressing ABCC1 displayed significant resistance to thiosemicarbazones (Dp44mT, COTI-2, DpC) in both their metal-free and metal-bound forms. Vesicular transport assays further demonstrated that ABCC1 actively transports the Fe-GSH complex, formed under physiological glutathione levels, indicating its role in regulating the labile iron pool and reducing intracellular iron toxicity. These findings underscore the importance of transporter-chelator interactions in shaping drug resistance and sensitivity and highlight the intricate roles of ABC transporters in modulating chelator activity.

We report the synthesis and biological evaluation of disulfide-based prochelators featuring a 2-pyridyl-hydrazone motif and resulting in a tridentate (S,N,N) donor set as found in several antiproliferative chelators (e.g., Triapine, Dp44mT, DpC, COTI-2). Accordingly, the preformed iron complex FePH3 also leads to apoptosis and iron dysregulation, and its toxicity is enhanced when the antioxidant capacity of the cells is impaired. The incorporation of the 2-pyridyl-hydrazone motif in disulfide-based prochelators therefore combines iron sequestration with pro-oxidant effects that could enhance the pharmacological profile of this chelation approach for cancer applications.

TNBC cell lines harbouring frameshift and stop TP53 mutations exhibited reduced SOCE, lower CACNA1D expression, and resistance to thapsigargin-induced apoptosis compared to wild-type cells. This study identifies a novel link between TP53 mutation type and calcium signalling in TNBC. Reactivating mutant p53 with COTI-2 restores calcium-mediated apoptosis, supporting combination strategies targeting both TP53 dysfunction and calcium signalling.

Importantly, in contrast to the Fe(III) complexes of the clinically trialed thiosemicarbazones Triapine, COTI-2, and DpC, the Fe(III) complexes of PPTP4c4mT and PPTP4c4mSe did not induce detrimental oxy-myoglobin oxidation. This latter effect probably promoted their antiproliferative activity. Both ligands down-regulated multiple key receptors that display inter-receptor cooperation that leads to aggressive and resistant breast cancer.

PDOs maintained the histological and genetic characteristics of original cancer tissues. PDOs biobank opens up new perspectives for studying cancer cell biology and personalized medicine as a preclinical study platform.

The PPP4pT:Fe(III) complexes attenuated oxy-myoglobin oxidation significantly more than the clinically trialed thiosemicarbazones, Triapine, COTI-2, and DpC, or earlier thiosemicarbazone series. Incorporation of phenyl- and styryl-substituents led to steric blockade, preventing approach of the PPP4pT:Fe(III) complexes to the heme plane and its oxidation. The 1:1 Cu(II):PPP4pT complexes were inert to transmetalation and did not induce oxy-myoglobin oxidation.

Proteasome-mediated degradation was determined using the proteasome, inhibitor MG-132, while MYC half-life was measured using pulse chase experiments in the presence of cycloheximide. Co-treatment with COTI-2 and the MYC inhibitor, MYCi975 resulted in synergistic growth inhibition in all 4 mutant p53 cell lines investigated. The dual ability of COTI-2 to reactivate mutant p53 and degrade MYC should enable this compound to have broad application as an anticancer drug.

COTI-2 activity correlated with nitrogen mustard, cisplatin and gemcitabine, doxorubicin and selumetinib, with a trend for APR-246 with doxorubicin. Cisplatin synergy is consistent with P53's role in DNA damage. Different mechanisms of action may underlie disease specificity and offer better disease targeting.

Furthermore, their activities against drug-resistant cancer cells was investigated in comparison to COTI-2 and Triapine. These data revealed that, besides zinc, also iron and copper ions need to be considered to play a role in the mode of action and resistance development of these thiosemicarbazones. Moreover, we identified COTI-NMe as an interesting new drug candidate with improved anticancer activity and resistance profile.

Several such reactivating drugs are currently undergoing evaluation in clinical trials, including eprenetapopt (APR-246), COTI-2, arsenic trioxide and PC14586. With all of these ongoing trials, we should soon know if targeting mutant p53 can be used for cancer treatment. If any of these trials show clinical efficacy, it may be a transformative development for the treatment of patients with cancer since mutant p53 is so prevalent in this disease.

First, compounds targeting degradation or direct inhibition of WT p53, such as PM2, RITA, nutlin-3 and CH1iB, achieve p53 reactivation by affecting p53 inhibitors such as MDM2 and MDMX/4 or by preventing the breakdown of p53 by inhibiting the proteasomal complex. Second, compounds that directly affect mutated p53 by binding it and restoring the WT conformation and transcriptional activity (PRIMA-1, APR-246, COTI-2, CP-31398). Third, treatments that specifically affect HPV cancer cells by targeting the viral enzymes E6/E7 which are responsible for the breakdown of p53 such as Ad-E6/E7-As and bortezomib. In this review, we describe and discuss p53 regulation and its targeting in combination with existing therapies for HNSCC through a new classification of such cancers based on p53 mutation status and HPV infection.