NANOSTRUCTURED LIPID CARRIER CO-ENCAPSULATING PACLITAXEL AND BETA-CARYOPHYLLENE FOR BREAST CANCER TREATMENT AND MANAGEMENT OF CANCER-ASSOCIATED PAIN

Paclitaxel (PTX) remains one of the most effective chemotherapeutic agents for breast

cancer treatment. However, its clinical use is limited by poor aqueous solubility,

systemic toxicity, and the development of drug resistance. Nanostructured lipid

carriers (NLC) represent an attractive drug delivery platform capable of improving drug

bioavailability while reducing adverse effects. β-caryophyllene (BCP), a natural

sesquiterpene and selective CB2 receptor agonist, exhibits anti-inflammatory,

analgesic, and antitumor properties, making it a promising candidate for anticancer

therapy. An optimized NLC formulation co-encapsulating PTX and BCP (NLC-BCP-

PTX) was developed using myristyl myristate, capryc/caprilic triglyceride and Pluronic

F-68. Characterization comprised DLS, NTA, TEM/Cryo-EM analyses plus

encapsulation efficiency (%EE) and in vitro release studies. Cytotoxicity was evaluated

by MTT assay in murine (4T1) and human (MCF-7 and MDA-MB-231) breast cancer

cell lineages. Therapeutic efficacy was further investigated in an orthotopic 4T1-breast

cancer model through tumor growth, survival, and mechanical nociceptive threshold

assessment, using the electronic von Frey test. NLC-BCP-PTX showed mean particle

sizes of 173 nm, low polydispersity index (0.153), negative zeta potentials, particle

concentration of ca. 10¹³ particle/mL, and high %EE for PTX (99.9%) and BCP

(99.8%). TEM/Cryo-EM confirmed the homogeneous spherical morphology of the NLC

that provided sustained release over 24 h, for both compounds. The cytotoxic activity

of the formulation towards control fibroblasts was lower, but not against tumor cells in

which it was comparable to that of commercial PTX. In vivo, treatment with NLC-BCP-

PTX was associated with improved survival and modulation of mechanical nociceptive

responses after repeated administrations. These findings demonstrate the feasibility

of co-encapsulating PTX and BCP in NLC and support further investigation of this

formulation for the treatment of breast cancer.