Biodegradable Polymeric Nanoparticles for Therapeutic Cancer Treatments

Purpose: Biodegradable polymeric nanoparticles have great potential to improve cancer therapy by enabling targeted delivery, triggered release, and reduced off-target toxicity. This review addresses how such nanocarriers can be engineered to overcome systemic, organ-level, and cellular barriers and to target cancer cells, tumour vasculature, and immune cells for anticancer therapy.

Hypothesis: This is a review article and does not test a single formal hypothesis. Its central premise is that biodegradable polymeric nanoparticles can be rationally engineered — through polymer chemistry, stimuli-responsive design, and active/passive targeting — to safely and effectively deliver diverse anticancer agents to the tumour microenvironment and immune system, thereby improving therapeutic efficacy and reducing adverse effects.

Aims: Review biodegradable polymeric nanoparticle formulations for cancer drug delivery. - Describe natural and synthetic biodegradable polymers used as nanocarriers. - Explain stimuli-responsive strategies for intracellular, extracellular, and externally triggered release. - Discuss targeting approaches: passive EPR, active ligand-mediated targeting, anti-angiogenesis, and immunoengineering. - Summarise selected clinical trial results for biodegradable polymeric nanomedicines in cancer.

Delivery system: Nanoparticle formulations: Solid nanoparticles, core–shell nanoparticles, polymeric micelles, and polyplexes. - Natural polymers: Chitosan, dextran, alginate, gelatin, poly(L-lysine) (PLL). - Synthetic polymers: PLA, PLGA, PCL, cyclodextrin-based polymers, poly(β-amino esters) (PBAEs), chain-shattering polymers, and functional polyester libraries. - Payloads: Small-molecule chemotherapeutics (DOX, paclitaxel, docetaxel, cisplatin, camptothecin, combretastatin), nucleic acids (siRNA, miRNA, mRNA, pDNA), peptides/proteins (NuBCP-9, Bcl-2 peptide), and immunomodulatory agents. - Targeting ligands: Folate, transferrin, hyaluronic acid (CD44), RGD peptides, prostate-specific membrane antigen (PSMA) ligands. - Stimuli-responsive triggers: pH, redox/glutathione, temperature, enzymes, light/NIR, ultrasound, magnetic field. - Immunoengineering platforms: Cancer vaccines, artificial antigen-presenting cells (aAPCs), checkpoint blockade delivery, and in situ CAR T-cell programming.

Approach: Review of in vitro and in vivo preclinical literature and selected clinical trials. Model systems include numerous cancer cell lines (e.g., glioblastoma, prostate, melanoma, ovarian, breast, lung) and mouse tumour models. Clinical data are summarised for CALAA-01, BIND-014, NC-6004, CRLX101, and NK105. No new primary experiments are reported.

Key methods: Nanoparticle characterisation: Size, charge, stability, and cargo loading/release. - Cellular studies: Uptake, endosomal escape, transfection/gene silencing, cytotoxicity. - In vivo studies: Tumour accumulation, biodistribution, tumour growth inhibition, survival. - Clinical endpoints: Safety, toxicity, pharmacokinetics, overall response rate, stable disease.

Key results: PBAE nanoparticles delivered DNA encoding CAR to T cells in vivo; reprogrammed T cells expressed CAR for weeks, causing tumour regression and prolonged survival in a mouse leukaemia model. - PLA nanoparticles delivering NuBCP-9 peptide to solid tumours in mice caused complete tumour regression and 100% survival. - Chitosan nanoparticles loaded with Gal-1 siRNA reduced Gal-1 expression by 50% in glioblastoma in vivo. - Clinical trial results: - CALAA-01 (cyclodextrin, transferrin-targeted siRNA): safe with minimal liver/kidney toxicity; best response was stable disease in one melanoma patient for 4 months. - BIND-014 (PSMA-targeted PLGA/docetaxel): phase I; 6 of 52 patients responded, one complete response; 12% overall response rate. - NC-6004 (PEG-poly(amino acid) micelle/cisplatin): phase I; dose-limiting toxicity increased 34-fold; stable disease >4 weeks in 7 of 17 patients. - CRLX101 (cyclodextrin-camptothecin): phase II; measurable tumour reduction in 74% of 22 patients with platinum-resistant ovarian cancer; 16% response rate by RECIST. - NK105 (PEG-polyaspartate/paclitaxel micelle): phase I MTD 15 times higher than free paclitaxel; phase II 25% overall response rate (2 complete, 12 partial responses). - Stimuli-responsive systems demonstrated triggered release via pH, redox, temperature, enzymes, light, ultrasound, and magnetic field; PLGA/black phosphorus quantum dot photothermal therapy caused tumours in mice to shrink and regress.

Interpretation: Biodegradable polymeric nanocarriers have shown great promise to increase the efficacy and safety of cancer therapies by enabling customised delivery of small molecules, biologics, and nucleic acids. Their degradation under physiological conditions, combined with environmental and external trigger responsiveness, allows spatial and temporal control of drug release. The authors argue that further development could bring new combinations and multimodal treatments to the clinic, especially in anti-angiogenic therapy and cancer immunotherapy.

Limitations: This is a review, not a primary study; no new experimental data or meta-analysis. - Most discussed systems remain preclinical; clinical data are limited to a small number of formulations. - Long-term safety, immunogenicity, scalable manufacturing, and regulatory issues are not fully addressed. - Clinical responses are modest in several trials, and passive targeting still plays a major role even with active targeting ligands. - No large-animal validation or detailed toxicity across diverse patient populations is presented.