Camptothecin Research Articles

Characterization of camptothecin biosynthesis in endophytic fungus from Camptotheca acuminate.

Lysosome-targeted theranostics: Integration of real-time fluorescence imaging and controlled drug delivery via Zn(II)-Schiff Base complexes.

Camptothecin (CPT) is a natural alkaloid with potent antiproliferative activity, mediated by the inhibition of Topoisomerase I (Topo I), an essential enzyme for deoxyribonucleic acid (DNA) replication. However, its clinical application has been limited by low solubility and the instability of the lactone ring under physiological conditions, both of which decrease its efficacy. Semi-synthetic analogs such as irinotecan (CPT-11) and topotecan (TPT) have been developed and approved for the treatment of various types of cancer; however, challenges related to drug resistance and side effects continue to arise. Therefore, nanomedicine and nanoparticle-based delivery systems, including nanoemulsions, liposomes, and antibody–drug conjugates (ADCs), emerge as promising strategies to improve the stability, bioavailability, and effectiveness of CPT, despite significant challenges such as scalability, pharmacokinetic variability, and regulatory requirements. This review discusses recent advances in CPT, its analogs, and these delivery platforms, highlighting its potential to optimize cancer therapy and reduce toxicity while outlining translational challenges such as scalability, pharmacokinetic variability, and regulatory requirements.

Background: Photostability assessment is a critical component in the development of drug products, particularly for antibody–drug conjugates (ADCs) containing light-sensitive small molecules such as camptothecin (CPT) and its derivatives. ADCs conjugated with CPT derivative payloads often require extensive formulation and drug product development to ensure product stability due to their unique light-induced degradation pathways. In this study, we assessed the photostability of two ADC molecules with a CPT derivative payload (deruxtecan, DXd). Methods: Following light exposure, the stability of ADCs was assessed by examining critical quality attributes, such as aggregation and photodegradation products of the antibody, payload, and formulation excipients, using advanced liquid chromatography and mass spectrometry techniques. Results: Our results revealed key degradation pathways, including the formation of high-molecular-weight (HMW) species, payload degradation, and post-translational modifications (PTMs) on amino acid residues in the antibodies. Additionally, the DXd payload amplified the photosensitivity of the formulation solution, leading to histidine degradation in the formulation buffer and subsequent pH changes. To enhance the stability of ADCs for manufacturing and therapeutic use, we developed a robust formulation by systematic buffer screening and a targeted evaluation of selected antioxidant excipients. Further investigations into light conditions revealed that DXd ADCs are particularly sensitive to short-wavelength light. When evaluating the container closure system, it was demonstrated that using amber vials is a viable option for protecting against light-induced degradation. Conclusions: This report outlines a comprehensive strategy to address photo instability in DXd ADC drug product development, focusing on formulation optimization, controlled manufacturing light settings, and the option of using protective containers to ensure product stability.

Lipid nanoparticSle (LNP) represents the most advanced mRNA delivery platform for the development of effective cancer therapeutics. Nevertheless, conventional LNP-mRNA systems are hindered by inadequate endosomal release capability and a lack of synergistic integration with complementary therapeutic approaches. Herein, a reactive oxygen species (ROS)-responsive prodrug-doped LNP (LNP-Pro) that can enhance mRNA delivery efficacy and enable synergistic anti-tumor therapy is reported. A camptothecin (CPT)-based prodrug, conjugated to a PEG-containing block polymer via a ROS-cleavable linker, is successfully incorporated into clinically approved LNP formulations shown in a report. It shows that LNP-Pro can respond to the elevated ROS microenvironment in tumor cells, displaying superior delivery capacity in tumor cells relative to normal cells. Furthermore, LNP-Pro exhibits significantly enhanced mRNA delivery efficacy compared to conventional formulations. In vitro and in vivo studies confirm that LNP-Pro loaded with therapeutic mRNA synergizes with CPT chemotherapeutic to induce tumor cell apoptosis, achieving significant tumor growth inhibition in a murine model with excellent biocompatibility. Thus, this strategy integrates stimulus-responsive prodrugs with LNP systems, providing a versatile platform for mRNA-based cancer therapy.

A dynamic protein corona substitution strategy for activatable imaging-guided synergistic theranostics in triple-negative breast cancer

Controlled self-organization of amphiphilic phospholipid camptothecin (CPT) conjugates (named PCCs) selectively forms supramolecular nanotubes with varying lengths and polydispersity. Our study elucidates the underlying mechanisms governing PCC assembly, demonstrating that π-π stacking interactions derived from the planar, conjugated structure of CPT play a pivotal role in nanotube formation. Precise modulation of the hydrophobic characteristics of PCC linkers enables fine-tuning of π-stacking strength, thereby controlling the length of the nanotubes, ranging from the nano- to micro-scale. With exceptionally high drug-loading efficiencies (43.9% to 52.3%) and stimulus-responsive release properties, the optimized PCC nanotubes exhibit tumor-selective cytotoxicity of 20- to 50-fold greater potency against tumor cells compared to normal cells. Furthermore, PCC nanotubes of intermediate length (0.3-0.5µm) display prolonged circulation times than conventional liposomes, resulting in enhanced tumor-targeting and therapeutic efficacy.

Combined use of different drugs and therapy modes has been effective in improving tumor therapy efficiency and reducing side effects. However, synergistic anticancer efficiency and highly responsive drug release still remain challenging. Herein, we found that camptothecin (CPT), doxycycline (DOXY), and IR780 exhibit a synergistic anticancer effect on CT26 colorectal cancer cells. Thereafter, a redox dual-responsive CPT/DOXY hybrid dimer, CPT-SeSe-DOXY, was synthesized via the -SeSe- linkage. As a control, CPT-SS-DOXY was also synthesized. Both dimers were able to self-assemble with IR780 and DSPE-PEG-iRGD into multifunctional, stimuli-responsive, aqueous-dispersible, and spherical nanoparticles (NPs) with diameters of 83-87 nm. The C-SeSe-D/I/RGD NPs showed significantly stronger responsiveness to glutathione, H2O2, and near-infrared (NIR) lasers, reflected by dramatically higher responsive drug release ratios and stronger generation of 1O2 upon NIR laser irradiation, than the C-SS-D/I/RGD NPs. They can be highly taken up by CT26 cells, while hardly taken up by normal colorectal cells. In addition, they exhibited a very efficacious killing property against CT26 cells. The cell viability with C-SeSe-D/I/RGD NPs (with NIR laser) at 4.0 μg·mL-1 equivalent CPT at hypoxic conditions reached as low as ∼7.8%. The treatment can induce strong mitochondrial depolarization, ATP depletion, reactive oxygen species (ROS) generation, and therefore high cell apoptosis, even in hypoxic cultures. They can highly accumulate in tumors and lead to as high as 90.8% tumor growth inhibition under an NIR laser. Collectively, the C-SeSe-D/I/RGD NPs possess sensitive multistimuli-responsive capabilities and efficacious chemo/photothermal/photodynamic combined tumor therapy, exhibiting great potential in clinical applications.

A light-controlled dextran nano-immunomodulator amplifies immunogenic cell death for cancer immunotherapy.

Smart co-delivery of Erlotinib and Camptothecin using silica-coated gold nanorods functionalized with recombinant anti-bone morphogenetic protein receptor type I (BMPR-AI).

Preparation of mitochondria-targeted camptothecin derivatives for the imaging and antiproliferation of colorectal cancer.

Efficient NMR spectroscopy approach for the determination of the relative configuration of Δ5,6Δ11,12-jatrophane diterpenes and their chemotherapy sensitization activities.

Deuterium substitution at the intolerable site as a strategy to mitigate the toxicity of camptothecin derivatives.

Synthesis and characterization of multifunctional mesoporous silica nanoparticles with dual targeting and dual-mode imaging for cancer therapy.

Camptothecin (CPT) is a potent topoisomerase I inhibitor with promising anticancer potential. However, its poor solubility and stability present major obstacles in pharmaceutical formulations. Rutin, a plant-derived quercetin glycoside, also exhibits anticancer activity but suffers from limited solubility. This study explores a novel combination of CPT and Rutin in a liposomal drug delivery system. To enhance CPT solubility and encapsulation, hydroxypropyl-β-cyclodextrin (HPβCD) complexation was employed. High-performance liquid chromatography (HPLC) with UV detection was used for analysis. The CPT-HPβCD complex was prepared via different methods and characterized by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FTIR) Spectroscopy, and Nuclear Magnetic Resonance (NMR). Liposomes loaded with Rutin and CPT-HPβCD were formulated and evaluated for size, charge, encapsulation efficiency, and in vitro release. Results showed that the solubility of CPT was significantly increased from 1.09µM to a range of (1.68-8.5) µM using different concentrations of HPβCD. Characterization proved the formation of the complex and the kneading method of preparation was found to be superior to other methods like solvent evaporation with an encapsulation efficiency of 64.6 ± 2.5%. The prepared Liposomes showed particle size around 20 nm with negative charge and 60 % cumulative release of rutin from the liposomes was achieved and CPT up to 60% compared to 10 % from the formula 1 (without complexation) with controlled release pattern.

Endophytic microorganisms (EMs) residing in medicinal plants form a promising resource of anticancer compounds such as camptothecin (CPT). Given the increasing therapeutic demand for CPT, its sustainable production is of high significance. This study has investigated the EMs isolated from different parts of Ophiorrhiza mungos for the CPT biosynthetic potential. Preliminary screening of EMs for the CPT synthesis was carried out by HPLC analysis of culture extracts, and the HPLC-positive extracts were further confirmed via LC-MS/MS. From a total of 175 EMs screened in the study, 17 strains (14 bacterial and 3 fungal) were found to be CPT producing, with most of them being sourced from the root tissues. Among the bacterial strains, Alcaligenes faecalis subsp. phenolicus S18 exhibited the highest CPT yield (1294.52 μg/L) followed by Bacillus tequilensis (309.02 μg/L). From the fungal strains, Aspergillus sp., S109, S42, and S111 yielded CPT of 22.07, 18.98, and 13.26 μg/L, respectively. Overall, CPT yield among the bacterial producers ranged from 1294.52 to 5.16 μg/L, predominantly from the Bacillus, Acinetobacter, Alcaligenes, and Pseudomonas genera. This study provides the first report on the CPT production by A. faecalis and Aspergillus sp. isolated from O. mungos, and also the first documentation of CPT synthesis in Stenotrophomonas, Fictibacillus, Acinetobacter, and Pseudomonas genera. These findings highlight the potential of novel microbial sources as high-yielding, reliable, and cost-effective alternatives to support commercial CPT production.

To protect the genome from the formation of DNA breaks by nucleases involved in DNA repair, cells have evolved multiple levels of regulatory strategies. One key regulator of nuclease activity is the scaffold protein SLX4, which plays important roles in repairing DNA damage induced by mitomycin C (MMC) and camptothecin (CPT) as well as in the resolution of stalled replication forks. Since SLX4 regulates the activity of nucleases such as SLX1, MUS81, and XPF, whose uncontrolled activity could jeopardize genome integrity, the protein level and localization of SLX4 must be tightly regulated. Here, we show that the ubiquitin E3 ligase RNF4 is associated with SLX4 and is responsible for the ubiquitin-dependent proteasomal degradation of excessive SLX4 under normal conditions. Conversely, promyelocytic leukemia nuclear bodies (PML NBs) promote SLX4 stability. In PML NBs, the stability of SLX4 is maintained by the deubiquitinase USP7, managing the amount of SLX4 necessary for a rapid response to DNA damage. These findings suggest that SLX4 and its associate nucleases are confined within PML NBs and that the optimal protein level of SLX4 is maintained by the coordinated activities of RNF4 and USP7. Our findings provide insight into how cells effectively control the potentially harmful activities of nucleases in the absence of DNA damage by a spatial regulatory mechanism.

The blocking interaction between p53 and its negative regulator MDM2 is an engaging therapeutic strategy for antitumor drug development, and there are several drug candidates of p53-MDM2 inhibitors in clinical trials. In the present study, novel drug conjugates of p53-MDM2 inhibitors and topoisomerase I (TOP1) inhibitors have been designed based on bioinformatics analysis results of ten tumor tissues. Among them, ZM484 showed potent antiproliferative activity against three cell lines HCT116, SJSA-1, and A549, with the strongest p53-MDM2 and TOP1 inhibitory activity. Additionally, the treatment of compound ZM484 significantly reduced the tumor growth of HCT116 in BALB/c nude mice mode. Furthermore, our data highlighted the superior stability and good pharmacokinetic properties of compound ZM484. Using LC-MS analysis, we identified that compound ZM484 is capable of effectively releasing camptothecin (CPT) and the potent p53-MDM2 inhibitor 8a upon coincubation with DTT. Therefore, compound ZM484 could be a potential drug-conjugate candidate for the treatment of colorectal cancer.

Herpes simplex virus type 1 (HSV-1) is a double-stranded DNA virus that infects most of the human population. We previously found that cellular topoisomerase I (TOP1) associates with the HSV-1 genome throughout infection. TOP1 relieves topological stress on DNA to enable and regulate transcription, DNA replication, and DNA repair. We hypothesized that TOP1 contributes to these key viral processes because HSV-1 does not encode a topoisomerase. We found that TOP1 inhibition with camptothecin (CPT) or β-Lapachone results in a significant reduction in viral yield. The effects of CPT are reversible and occur in a dose-dependent manner, independent of strain and cell type. CPT treatment results in a decrease in viral gene expression and DNA replication, with replication defects observed at all concentrations tested. Defects in viral gene expression are not restricted to a specific gene class. However, the timing and extent of the observed defects are dose dependent. We also demonstrate that if CPT is added to cells after the onset of viral DNA replication, subsequent rounds of replication are inhibited, indicating that the replication defect observed is not simply the result of prior steps in the infectious cycle being blocked. Together, these results demonstrate that CPT is a potent inhibitor of HSV-1 infection, supporting the hypothesis that TOP1 is active on HSV-1 genomes during infection.IMPORTANCEHSV-1 is a common human pathogen. It utilizes both viral and cellular factors to facilitate infection. We previously characterized the proteins that associate with HSV-1 DNA throughout infection. One of these proteins, which has been largely unexplored in the context of HSV-1 infection, is TOP1. TOP1 functions to relieve topological stress to regulate transcription, DNA replication, and other processes that involve DNA cleavage and unwinding. Our findings support a role for TOP1 in HSV-1 DNA replication and gene expression and highlight the potential to target TOP1 activity or interactions for antiviral therapy.

Topoisomerase I (Top1) alleviates DNA supercoiling during replication and transcription, but its catalytic cycle can be hijacked by chemotherapeutic agents such as camptothecin (CPT), stabilizing Top1-DNA covalent complexes (Top1cc) that threaten genome integrity. Efficient resolution of these trapped intermediates is crucial to prevent replication stress, DNA breaks, and cell death. Poly (ADP-ribose) polymerase 1 (PARP1) is a key sensor of Top1cc, facilitating repair by recruiting tyrosyl-DNA phosphodiesterase 1 (TDP1) and modifying chromatin to promote lesion accessibility. Beyond this canonical pathway, emerging evidence highlights PARP1-independent mechanisms such as endo nucleolytic cleavage, proteolytic degradation of Top1 and replication-associated processing. Intriguingly, PARP1 appears to act as a molecular switch between TDP1 and the endonuclease pathway for the repair of Top1cc. This review highlights mechanisms of PARP1-dependent and -independent Top1cc repair pathways, their interplay and redundancy, and how their targeting can enhance Top1-based cancer therapies and overcome resistance.