Phase I dose-escalation study of F14512, a polyamine-vectorized topoisomerase II inhibitor, in patients with platinum-refractory or resistant ovarian cancer

Polyamine-Drug Conjugates: Do They Boost Drug Activity?

Over the past two decades, the strategy of conjugating polyamine tails with bioactive molecules such as anticancer and antimicrobial agents, as well as antioxidant and neuroprotective scaffolds, has been widely exploited to enhance their pharmacological profile. Polyamine transport is elevated in many pathological conditions, suggesting that the polyamine portion could improve cellular and subcellular uptake of the conjugate via the polyamine transporter system. In this review, we have presented a glimpse on the polyamine conjugate scenario, classified by therapeutic area, of the last decade with the aim of highlighting achievements and fostering future developments.

c-MYC-Driven Polyamine Metabolism in Ovarian Cancer: From Pathogenesis to Early Detection and Therapy

c-MYC and its paralogues MYCN and MYCL are among the most frequently amplified and/or overexpressed oncoproteins in ovarian cancer. c-MYC plays a key role in promoting ovarian cancer initiation and progression. The polyamine pathway is a bona fide target of c-MYC signaling, and polyamine metabolism is strongly intertwined with ovarian malignancy. Targeting of the polyamine pathway via small molecule inhibitors has garnered considerable attention as a therapeutic strategy for ovarian cancer. Herein, we discuss the involvement of c-MYC signaling and that of its paralogues in promoting ovarian cancer tumorigenesis. We highlight the potential of targeting c-MYC-driven polyamine metabolism for the treatment of ovarian cancers and the utility of polyamine signatures in biofluids for early detection applications.

Symmetric lipophilic polyamines exhibiting antitumor activity

Unsymmetric lipophilic polyamine derivatives are considered as potential antitumor agents. Here, a series of novel symmetric lipophilic polyamines (LPAs) based on norspermine and triethylenetetramine (TETA) backbones bearing alkyl substituents with different lengths (from decyl to octadecyl) at C(1) atom of glycerol were synthesized. Performed screening of the cytotoxicity of novel compounds on the panel of tumor cell lines (MCF-7, KB-3-1, B16) and non-malignant fibroblasts hFF3 in vitro revealed a correlation between the length of the aliphatic moieties in LPAs and their toxic effects - LPAs with the shortest decyl substituent were found to exhibit the highest cytotoxicity. Furthermore, norspermine-based LPAs displayed somewhat more pronounced cytotoxicity compared with their TETA-based counterparts. Further mechanistic studies demonstrated that hit LPAs containing the norspermine backbone and tetradecyl or decyl substituents efficiently induced apoptosis in KB-3-1 cells. Moreover, decyl-bearing LPA inhibited motility and enhanced adhesiveness of murine B16 melanoma cells in vitro, showing promising antimetastatic potential. Thus, developed novel symmetric norspermine-based LPAs can be considered as promising anticancer chemotherapeutic candidates.

Suppression of oxidative phosphorylation and IDH2 sensitizes colorectal cancer to a naphthalimide derivative and mitoxantrone

Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. Oxidative phosphorylation (OXPHOS) has attracted a considerable attention in CRC. It is of great interest to explore novel therapies that inhibit OXPHOS for CRC treatment. Compound 6c is a novel naphthalimide derivative. However, the effects of 6c on CRC and the underlying mechanism are unclear. In this study, 6c suppressed CRC tumor growth and metastasis. RNA-seq data showed that 6c triggered the inhibition of OXPHOS and tricarboxylic acid cycle. 6c specifically inhibited mitochondrial complex III activity and the expression of isocitrate dehydrogenase 2 (IDH2), resulting in oxidative stress. Antioxidants reversed 6c-induced cell death, senescence, and autophagosomes formation. 6c inhibited autophagy flux; however, pretreatment with autophagy inhibitors resulted in the reduction of 6c-induced cytoplasmic vacuolization and proliferation inhibition. Moreover, combinatory treatment of 6c and mitoxantrone (MIT) showed stronger inhibitory effects on CRC compared with the single agent. Downregulation of IDH2 induced reactive oxygen species production, leading to MIT accumulation and autophagic cell death after co-treatment with 6c and MIT. In summary, our findings indicated 6c as a promising candidate for CRC treatment.

Synthesis and biological evaluation of chalcone-polyamine conjugates as novel vectorized agents in colorectal and prostate cancer chemotherapy

The aim of this study was to synthesize chalcone-polyamine conjugates in order to enhance bioavailability and selectivity of chalcone core towards cancer cells, using polyamine-based vectors. Indeed, it is well-known that polyamine transport system is upregulated in tumor cells. 3',4,4',5'-tetramethoxychalcone was selected as parent chalcone since it was found to be an efficient anti-proliferative agent on various cancer cells. A series of five chalcone-polyamine conjugates was obtained using the 4-bromopropyloxy-3',4',5'-trimethoxychalcone as a key intermediate. Chalcone core and polyamine tails were fused through an amine bond. These conjugates were found to possess a marked in vitro antiproliferative effect against colorectal (HT-29 and HCT-116) and prostate cancer (PC-3 and DU-145) cell lines. The most active conjugate (compound 8b) was then chosen for further biological evaluations to elucidate mechanisms responsible for its antiproliferative activity. Investigations on cell cycle distribution revealed that this conjugate can prevent the proliferation of human colorectal and prostate cancer cells by blocking the cell cycle at the G1 and G2 phase, respectively. Flow cytometry analysis revealed a sub-G1 peak, characteristic of apoptotic cell population and our inquiries highlighted apoptosis induction at early and later stages through several pro-apoptotic markers. Therefore, this chalcone-N1-spermidine conjugate could be considered as a promising agent for colon and prostatic cancer adjuvant therapy.

The Role of p53-Mediated Signaling in the Therapeutic Response of Colorectal Cancer to 9F, a Spermine-Modified Naphthalene Diimide Derivative

Colorectal cancer (CRC) is one of the most prevalent cancers due to its frequency and high rate of mortality. Polyamine-vectorized anticancer drugs possess multiple biological properties. Of these drugs, 9F has been shown to inhibit tumor growth and the metastasis of hepatocellular carcinoma. This current study aims to investigate the effects of 9F on CRC and determine its molecular mechanisms of action. Our findings demonstrate that 9F inhibits CRC cell growth by inducing apoptosis and cell cycle arrest, and suppresses migration, invasion and angiogenesis in vitro, resulting in the inhibition of tumor growth and metastasis in vivo. Based on RNA-seq data, further bioinformatic analyses suggest that 9F exerts its anticancer activities through p53 signaling, which is responsible for the altered expression of key regulators of the cell cycle, apoptosis, the epithelial-to-mesenchymal transition (EMT), and angiogenesis. In addition, 9F is more effective than amonafide against CRC. These results show that 9F can be considered as a potential strategy for CRC treatment.

Randomized, double-blind trial of F14512, a polyamine-vectorized anticancer drug, compared with etoposide phosphate, in dogs with naturally occurring lymphoma

Purpose: F14512 is an epipodophyllotoxin derivative from etoposide, combined with a spermine moiety introduced as a cell delivery vector. The objective of this study was to compare the safety and antitumor activity of F14512 and etoposide phosphate in dogs with spontaneous non-Hodgkin lymphoma (NHL) and to investigate the potential benefit of F14512 in P-glycoprotein (Pgp) overexpressing lymphomas.

Experimental Design: Forty-eight client-owned dogs with intermediate to high-grade NHL were enrolled into a randomized, double-blind trial of F14512 versus etoposide phosphate. Endpoints included safety and therapeutic efficacy.

Results: Twenty-five dogs were randomized to receive F14512 and 23 dogs to receive etoposide phosphate. All adverse events (AEs) were reversible, and no treatment-related death was reported. Hematologic AEs were more severe with F14512 and gastrointestinal AEs were more frequent with etoposide phosphate. F14512 exhibited similar response rate and progression-free survival (PFS) as etoposide phosphate in the global treated population. Subgroup analysis of dogs with Pgp-overexpressing NHL showed a significant improvement in PFS in dogs treated with F14512 compared with etoposide phosphate.

Conclusion: F14512 showed strong therapeutic efficacy against spontaneous NHL and exhibited a clinical benefice in Pgp-overexpressing lymphoma superior to etoposide phosphate. The results clearly justify the evaluation of F14512 in human clinical trials.

Topoisomerases and cancer chemotherapy: recent advances and unanswered questions

DNA topoisomerases are enzymes that catalyze changes in the torsional and flexural strain of DNA molecules. Earlier studies implicated these enzymes in a variety of processes in both prokaryotes and eukaryotes, including DNA replication, transcription, recombination, and chromosome segregation. Studies performed over the past 3 years have provided new insight into the roles of various topoisomerases in maintaining eukaryotic chromosome structure and facilitating the decatenation of daughter chromosomes at cell division. In addition, recent studies have demonstrated that the incorporation of ribonucleotides into DNA results in trapping of topoisomerase I (TOP1)–DNA covalent complexes during aborted ribonucleotide removal. Importantly, such trapped TOP1–DNA covalent complexes, formed either during ribonucleotide removal or as a consequence of drug action, activate several repair processes, including processes involving the recently described nuclear proteases SPARTAN and GCNA-1. A variety of new TOP1 inhibitors and formulations, including antibody–drug conjugates and PEGylated complexes, exert their anticancer effects by also trapping these TOP1–DNA covalent complexes. Here we review recent developments and identify further questions raised by these new findings.