A Comparison of Di- and Trinuclear Platinum Complexes Interacting with Glycosaminoglycans for Targeted Chemotherapy.

Heparan sulfate proteoglycans (HSPGs) and their associated proteins aid in tumor progression through modulation of biological events such as cell invasion, angiogenesis, metastasis, and immunological responses. Metalloshielding of the anionic heparan sulfate (HS) chains by cationic polynuclear platinum complexes (PPCs) prevents the HS from interacting with HS-associated proteins and thus diminishes the critical functions of HSPG. Studies herein exploring the PPC-HS interactions demonstrated that a series of PPCs varying in charge, nuclearity, distance between Pt centers, and hydrogen-bonding ability influence HS affinity. We report that the polyamine-linked complexes have high HS affinity and display excellent in vivo activity against breast cancer metastases and those arising in the bone and liver compared to carboplatin. Overall, the PPC-HS niche offers an attractive approach for targeting HSPG-expressing tumor cells.

Exploitation of Sulfated Glycosaminoglycan Status for Precision Medicine of Triplatin in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is a subtype of breast cancer lacking targetable biomarkers. TNBC is known to be most aggressive and when metastatic is often drug-resistant and uncurable. Biomarkers predicting response to therapy improve treatment decisions and allow personalized approaches for patients with TNBC. This study explores sulfated glycosaminoglycan (sGAG) levels as a predictor of TNBC response to platinum therapy. sGAG levels were quantified in three distinct TNBC tumor models, including cell line-derived, patient-derived xenograft (PDX) tumors, and isogenic models deficient in sGAG biosynthesis. The in vivo antitumor efficacy of Triplatin, a sGAG-directed platinum agent, was compared in these models with the clinical platinum agent, carboplatin. We determined that >40% of TNBC PDX tissue microarray samples have high levels of sGAGs. The in vivo accumulation of Triplatin in tumors as well as antitumor efficacy of Triplatin positively correlated with sGAG levels on tumor cells, whereas carboplatin followed the opposite trend. In carboplatin-resistant tumor models expressing high levels of sGAGs, Triplatin decreased primary tumor growth, reduced lung metastases, and inhibited metastatic growth in lungs, liver, and ovaries. sGAG levels served as a predictor of Triplatin sensitivity in TNBC. Triplatin may be particularly beneficial in treating patients with chemotherapy-resistant tumors who have evidence of residual disease after standard neoadjuvant chemotherapy. More effective neoadjuvant and adjuvant treatment will likely improve clinical outcome of TNBC.

Conformational Modulation of Iduronic Acid-Containing Sulfated Glycosaminoglycans by a Polynuclear Platinum Compound and Implications for Development of Antimetastatic Platinum Drugs.

1 H NMR spectroscopic studies on the 1:1 adduct of the pentasaccharide Fondaparinux (FPX) and the substitution-inert polynuclear platinum complex TriplatinNC show significant modulation of geometry around the glycosidic linkages of the FPX constituent monosaccharides. FPX is a valid model for the highly sulfated cell signalling molecule heparan sulfate (HS). The conformational ratio of the 1 C4 :2 S0 forms of the FPX residue IdoA(2S) is altered from ca. 35:65 (free FPX) to ca. 75:25 in the adduct; the first demonstration of a small molecule affecting conformational changes on a HS oligosaccharide. Functional consequences of such binding are suggested to be inhibition of HS cleavage in MDA-MB-231 triple-negative breast cancer (TNBC) cells. We further describe inhibition of metastasis by TriplatinNC in the TNBC 4T1 syngeneic tumour model. Our work provides insight into a novel approach for design of platinum drugs (and coordination compounds in general) with intrinsic anti-metastatic potential.