Advancements in assay design, detection techniques, signal transduction and enhancement strategies using smart nanomaterials.

Advanced inoperable triple-negative breast cancer (TNBC) comprises aggressive tumors with a modest pathological response to neoadjuvant chemotherapy. The concomitant use of chemoradiotherapy improves the pathological response rates. However, the dose-dependent systemic toxicity of clinical radiosensitizers with poor circulation half-life and limited passive bioavailability limits their clinical utility. We address these challenges by rationally designing a stealth and tumor microenvironment responsive nano-conjugate platform for the ultrasound-mediated on-demand spatio-temporal delivery of plant flavonoid curcumin as a combinatorial regimen with clinically approved paclitaxel for the neoadjuvant chemoradiotherapy of locally advanced triple-negative breast cancer (TNBC). Interestingly, the focused application of ultrasound at the orthotopic TNBC xenograft of NOD-SCID mice facilitated the immediate infiltration of nano-conjugates at the tumor interstitium, and conferred in vivo safety over marketed paclitaxel formulation. In addition, curcumin significantly potentiated the in vivo chemoradiotherapeutic efficacy of paclitaxel upon loading into nano-conjugates. This gets further enhanced by the concurrent pulse of ultrasound, as confirmed by PET-CT imaging, along with a significant improvement in the mice survival. The quadrapeutic apoptotic effect by the combination of paclitaxel, curcumin, radiation, and ultrasound, along with a reduction in the tumor microvessel density and cell proliferation marker, confers the broad chemo-radiotherapeutic potential of this regimen for radio-responsive solid tumors, as well as metastatic niches.

New treatments are needed to improve survival in children with rhabdomyosarcoma (RMS). Nicotinamide adenine dinucleotide (NAD+) biosynthesis, regulated by the enzymes nicotinic acid phosphoribosyltransferase (NAPRT) and nicotinamide phosphoribosyltransferase (NAMPT), represents a metabolic vulnerability due to high NAD+ turnover in cancers. Although NAMPT inhibitors (NAMPTi) show preclinical promise, clinical translation has been limited by toxicity and the lack of predictive biomarkers. In this study, we evaluated NAPRT expression in RMS and its potential as an actionable biomarker to guide NAMPTi therapy. NAPRT promoter methylation, transcript levels, and protein expression were assessed in RMS cells, patient-derived xenografts (PDX), and primary tumors (n = 109) from the Children’s Oncology Group. In vitro sensitivity to NAMPTi was tested in isogenic RMS cell lines, examining the role of NAPRT expression in mediating cytotoxicity and the ability of nicotinic acid (NA) to rescue viability. In vivo efficacy was assessed using cell-derived, NAPRT-isogenic, and orthotopic PDX models. NAPRT promoter hypermethylation was found in a subset of RMS models and patient samples. Immunohistochemistry showed loss of NAPRT protein in 30% to 40% of tumors, defined as <1% tumor cell staining. Methylation modestly correlated with protein expression. NAPRT-deficient cells were highly sensitive to NAMPTi, driven by NAD+ depletion and not reversible with NA. In vivo, NAMPTi induced significant tumor regression, which was not abrogated with NA administration in NAPRT-deficient models. NAPRT loss occurs in a subset of RMS and may offer a biomarker-driven strategy to expand the therapeutic window of NAMPTi. Further research is needed to understand NAPRT regulation and optimize biomarker assays in future clinical trials.

Supplementary Figure 5. Induction of apoptosis in RMS models with OT-82 treatment