cRGD-Functionalized Nanohybrid Conjugates Codelivering Temozolomide and Rapamycin for Treating Glioblastoma Multiforme: <i>In Vitro</i> and <i>In Vivo</i> Evaluation

The conventional treatment of glioblastoma multiforme primarily uses Temozolomide as a chemoadjuvant alongside debulking surgery and radiotherapy; however, resistance, as well as tumor recurrence, remains a common outcome. Employing combination therapy to target multiple pathways while improving delivery with advanced systems has always been sought after. Herein, we report cRGD-functionalized hybrid polymeric nanoconjugates that could deliver Temozolomide (TMZ) and rapamycin (RAP) (cRGD-Hybrid TMZ/R NCs) as a dual payload. The cRGD-Hybrid TMZ/R NCs were thoroughly characterized, exhibiting a particle size and surface zeta potential of 141.83 nm (PDI 0.233) and -0.168 mV, respectively. The nanoconjugates carrying TMZ and RAP as dual payloads were initially screened for synergism by determining their combination index in C6 and U87MG glioma cells. Further, <i>in vitro</i> cell-based assays showed improved cellular uptake, cytotoxicity, and apoptotic potential of hybrid nanoconjugates. Thereafter, the cRGD-Hybrid TMZ/R NCs were evaluated in a C6-cell-induced syngeneic orthotropic glioma model in <i>Sprague-Dawley</i> rats, exhibiting an improved therapeutic outcome including, reduced hemispherical width (RH/LH) ratios, tumor burden, and improved survival rates compared to the free drug(s) counterpart. The histopathological evaluation indicated no major sign of toxicity in vital organs such as heart, lungs, liver, kidney, and spleen, affirming the biocompatibility of the developed cRGD-Hybrid TMZ/R nanoconjugates. In conclusion, amalgamating the cRGD cell-penetrating peptide with polymer hybrid nanoconjugates presents a better approach for delivering multiple payloads in the treatment of GBM.