Functionalized Triblock Copolymer Vectors for the Treatment of Acute Lymphoblastic Leukemia

Nanotechnology-based diagnostics and therapeutics in acute lymphoblastic leukemia: a systematic review of preclinical studies

Background: Leukemia is a malignant disease that threatens human health and life. Nano-delivery systems improve drug solubility, bioavailability, and blood circulation time, and release drugs selectively at desired sites using targeting or sensing strategies. As drug carriers, they could improve therapeutic outcomes while reducing systemic toxicity. They have also shown promise in improving leukemia detection and diagnosis. The study aimed to assess the potential of nanotechnology-based diagnostics and therapeutics in preclinical human acute lymphoblastic leukemia (h-ALL). Methods: We performed a systematic search through April 2022. Articles written in English reporting the toxicity, efficacy, and safety of nanotechnology-based drugs (in the aspect of treatment) and specificity, limit of detection (LOD), or sensitivity (in the aspect of the detection field) in preclinical h-ALL were included. The study was performed according to PRISMA instructions. The methodological quality was assessed using the QualSyst tool. Results: A total of 63 original articles evaluating nanotechnology-based therapeutics and 35 original studies evaluating nanotechnology-based diagnostics were included in this review. As therapeutics in ALL, nanomaterials offer controlled release, targeting or sensing ligands, targeted gene therapy, photodynamic therapy and photothermic therapy, and reversal of multidrug-resistant ALL. A narrative synthesis of studies revealed that nanoparticles improve the ratio of efficacy to the toxicity of anti-leukemic drugs. They have also been developed as a vehicle for biomolecules (such as antibodies) that can help detect and monitor leukemic biomarkers. Therefore, nanomaterials can help with early diagnostics and personalized treatment of ALL. Conclusion: This review discussed nanotechnology-based preclinical strategies to achieve ALL diagnosis and therapy advancement. This involves modern drug delivery apparatuses and detection devices for prompt and targeted disease diagnostics. Nonetheless, we are yet in the experimental phase and investigational stage in the field of nanomedicine, with many features remained to be discovered as well as numerous problems to be solved.

The Emerging Potential of Parthenolide Nanoformulations in Tumor Therapy

Plant-derived sesquiterpene lactones are promising natural sources for the discovery of anti-cancer drugs. As an extensively studied sesquiterpene lactone, the tumor suppression effect of parthenolide (PTL) has been clarified by targeting a number of prominent signaling pathways and key protein regulators in carcinogenesis. Notably, PTL was also the first small molecule reported to eradicate cancer stem cells. Nevertheless, the clinical application of PTL as an antitumor agent remains limited, owing to some disadvantages such as low water solubility and poor bioavailability. Thus, nanomedicine has attracted much interest because of its great potential for transporting poorly soluble drugs to desired body sites. In view of the significant advantages over their free small-molecule counterparts, nanoparticle delivery systems appear to be a potential solution for addressing the delivery of hydrophobic drugs, including PTL. In this review, we summarized the key anticancer mechanisms underlined by PTL as well as engineered PTL nanoparticles synthesized to date. Therefore, PTL nanoformulations could be an alternative strategy to maximize the therapeutic value of PTL.

CD38-Directed Vincristine Nanotherapy for Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Although intensive chemotherapy greatly improved the survival rate, it is often accompanied by severe and lifelong side effects as a result of weak ALL selectivity. The intensive and poorly selective chemotherapy is also detrimental to patients' immune system. There is an urgent need to develop more selective and less toxic chemotherapy for ALL. Here, we report daratumumab-polymersome-vincristine (DP-VCR) as a CD38-directed nanotherapy for ALL. DP-VCR showed selective uptake in CD38-positive 697 and Nalm-6-Luc ALL cells and potent anti-ALL activity with an IC₅₀ as low as 0.06 nM VCR, which was 13.7-fold more potent than free VCR. In contrast, no toxicity to human peripheral blood mononuclear cells was detected for DP-VCR even at 108.3 nM VCR. The apoptotic assays confirmed a high selectivity of DP-VCR to CD38-positive ALL cells. DP-VCR exhibited superior treatment of both 697 and Nalm-6-Luc orthotopic ALL models to all controls, as revealed by significant survival benefit and marked reduction of leukemia burden in bone marrow, blood, spleen, and liver. Importantly, DP-VCR induced few side effects. DP-VCR emerges as a safe and potent nanotherapy for CD38-positive ALL.

Non-toxic polymer nanovectors for improved delivery of dexamethasone

Dexamethasone (Dex) is a highly insoluble front-line drug used in cancer therapy. Data from clinical trials indicates that the pharmacokinetics of Dex vary considerably between patients and prolonging drug exposure rather than increasing absolute dose may improve efficacy. Non-toxic, fully biodegradable Dex loaded nanovectors (NV) were formulated, via simple direct hydration within 10 min, as a vehicle to extend exposure and distribution in vivo. Dex-NV were just as effective as the free drug against primary human leukemia cells in vitro and in vivo. Importantly, high levels of DMSO solvent were not required in the NV formulations. Broad distribution of NV was seen rapidly following inoculation into mice. NV accumulated in major organs, including bone marrow and brain, known sanctuary sites for ALL. The study describes a non-toxic, more easily scalable system for improving Dex solubility for use in cancer and can be applied to other medical conditions associated with inflammation.

Biodegradable, Drug-Loaded Nanovectors via Direct Hydration as a New Platform for Cancer Therapeutics

The stabilization and transport of low-solubility drugs, by encapsulation in nanoscopic delivery vectors (nanovectors), is a key paradigm in nanomedicine. However, the problems of carrier toxicity, specificity, and producibility create a bottleneck in the development of new nanomedical technologies. Copolymeric nanoparticles are an excellent platform for nanovector engineering due to their structural versatility; however, conventional fabrication processes rely upon harmful chemicals that necessitate purification. In engineering a more robust (copolymeric) nanovector platform, it is necessary to reconsider the entire process from copolymer synthesis through self-assembly and functionalization. To this end, a process is developed whereby biodegradable copolymers of poly(ethylene glycol)-block-poly(trimethylene carbonate), synthesized via organocatalyzed ring-opening polymerization, undergo assembly into highly uniform, drug-loaded micelles without the use of harmful solvents or the need for purification. The direct hydration methodology, employing oligo(ethylene glycol) as a nontoxic dispersant, facilitates rapid preparation of pristine, drug-loaded nanovectors that require no further processing. This method is robust, fast, and scalable. Utilizing parthenolide, an exciting candidate for treatment of acute lymphoblastic leukemia (ALL), discrete nanovectors are generated that show strikingly low carrier toxicity and high levels of specific therapeutic efficacy against primary ALL cells (as compared to normal hematopoietic cells).

Investigating chemoresistance to improve sensitivity of childhood T-cell acute lymphoblastic leukemia to parthenolide

Current therapies for childhood T-cell acute lymphoblastic leukemia have increased survival rates to above 85% in developed countries. Unfortunately, some patients fail to respond to therapy and many suffer from serious side effects, highlighting the need to investigate other agents to treat this disease. Parthenolide, a nuclear factor kappa (κ)B inhibitor and reactive oxygen species inducer, has been shown to have excellent anti-cancer activity in pediatric leukemia xenografts, with minimal effects on normal hemopoietic cells. However, some leukemia initiating cell populations remain resistant to parthenolide. This study examined mechanisms for this resistance, including protective effects conferred by bone marrow stromal components. T-cell acute leukemia cells co-cultured with mesenchymal stem cells demonstrated significantly enhanced survival against parthenolide (73±11%) compared to cells treated without mesenchymal stem cell support (11±9%). Direct cell contact between mesenchymal cells and leukemia cells was not required to afford protection from parthenolide. Mesenchymal stem cells released thiols and protected leukemia cells from reactive oxygen species stress, which is associated with parthenolide cytotoxicity. Blocking cystine uptake by mesenchymal stem cells, using a small molecule inhibitor, prevented thiol release and significantly reduced leukemia cell resistance to parthenolide. These data indicate it may be possible to achieve greater toxicity to childhood T-cell acute lymphoblastic leukemia by combining parthenolide with inhibitors of cystine uptake.

α,ω-Diphenylalanine-End-Capping of PEG-PPG-PEG Polymers Changes the Micelle Morphology and Enhances Stability of the Thermogel

Pluronics F127 (P, PEG-PPG-PEG triblock copolymer) was coupled with diphenylalanine (FF) to prepare FF-end-capped Pluronics (FFPFF). With increasing temperature from 10 to 60 °C, the FFPFF self-assembled to vesicles in water. The unimer-to-vesicle transition accompanies endothermic enthalpy of 53.9 kcal/mol. Aqueous P and FFPFF solutions exhibited thermogelation in 15.0-24.0 wt %. The gel phase of FFPFF was stable up to 90 °C, whereas that of P turned into a sol again at 55-86 °C, indicating that end-capping with FF improved the gel stability against heat. In addition, the carboxylic acids of the FF end-groups can form coordination bonds with metal ions, and the gel modulus at 37 °C increased from 15-21 KPa (P) to 20-25 KPa (FFPFF) to 24-28 KPa (FFPFF-Zn), and the duration of gel against water-erosion increased from 24 h (P) to 60 h (FFPFF-Zn), leading to a useful biomaterial for sustained drug delivery. The FFPFF-Zn gels implanted in the rats' subcutaneous layer induced a mild inflammatory responses. Contrary to the previous end-capping of Pluronics by poly(lactic acid), polycarprolactone, carboxylic acid, and so on that weakened the gel stability, the diphenylalanine end-capping strengthened the stability of Pluronics gel against heat and water-erosion. This paper suggests that the control of polymer nanoassemblies directed by FF end-groups improves the mechanical properties and stability of the resulting thermogel and, thus, provides a useful drug delivery carrier with prolonged durability.