212Pb-Labeled Antibody 225.28 Targeted to Chondroitin Sulfate Proteoglycan 4 for Triple-Negative Breast Cancer Therapy in Mouse Models

Abstract

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with a poor prognosis. There is a clinical need for effective, targeted therapy strategies that destroy both differentiated TNBC cells and TNBC cancer initiating cells (CICs), as the latter are implicated in the metastasis and recurrence of TNBC. Chondroitin sulfate proteoglycan 4 (CSPG4) is overexpressed on differentiated tumor cells and CICs obtained from TNBC patient specimens, suggesting that CSPG4 may be a clinically relevant target for the imaging and therapy of TNBC. The purpose of this study was to determine whether α-particle radioimmunotherapy (RIT) targeting TNBC cells using the CSPG4-specific monoclonal antibody (mAb) 225.28 as a carrier was effective at eliminating TNBC tumors in preclinical models. To this end, mAb 225.28 labeled with 212Pb (212Pb-225.28) as a source of α-particles for RIT was used for in vitro Scatchard assays and clonogenic survival assays with human TNBC cells (SUM159 and 2LMP) grown as adherent cells or non-adherent CIC-enriched mammospheres. Immune-deficient mice bearing orthotopic SUM159 or 2LMP xenografts were injected i.v. with the targeted (225.28) or irrelevant isotype-matched control (F3-C25) mAbs, labeled with 99mTc, 125I, or 212Pb for in vivo imaging, biodistribution, or tumor growth inhibition studies. 212Pb-225.28 bound to adherent SUM159 and 2LMP cells and to CICs from SUM159 and 2LMP mammospheres with a mean affinity of 0.5 nM. Nearly ten times more binding sites per cell were present on SUM159 cells and CICs compared with 2LMP cells. 212Pb-225.28 was six to seven times more effective than 212Pb-F3-C25 at inhibiting SUM159 cell and CIC clonogenic survival (p < 0.05). Radiolabeled mAb 225.28 showed significantly higher uptake than radiolabeled mAb F3-C25 in SUM159 and 2LMP xenografts (p < 0.05), and the uptake of 212Pb-225.28 in TNBC xenografts was correlated with target epitope expression. 212Pb-225.28 caused dose-dependent growth inhibition of SUM159 xenografts; 0.30 MBq 212Pb-225.28 was significantly more effective than 0.33 MBq 212Pb-F3-C25 at inhibiting tumor growth (p < 0.01). These results suggest that CSPG4-specific 212Pb-225.28 is a useful reagent for RIT of CSPG4-expressing tumors, including metastatic TNBC.

Targeted alpha therapy for chronic lymphocytic leukaemia and non-Hodgkin’s lymphoma with the anti-CD37 radioimmunoconjugate 212Pb-NNV003

“…injected in mice. The uptake of 212 Pb-NNV003 in liver and kidneys is consistent with results from other studies [24,37], while the accumulation in spleen of 212 Pb-NNV003 is lower than has been measured for another 212 Pb labelled antibody [24]. The accumulation of 212 Pb-NNV003 reached maximum after 24 h, resulting in an absorbed dose of 9.1 and 6.2 in the Daudi and MEC-2 tumours, respectively.…”

“…The anti-tumour efficacy of 212 Pb has been demonstrated in preclinical studies; in several animal models of peritoneal cancer [16][17][18][19][20][21][22], prostate cancer, melanoma, pancreatic cancer and breast cancer [23][24][25][26]. It has also been applied in a pre-targeting setting [27,28].…”

In vivo safety profile of a CSPG4-directed IgE antibody in an immunocompetent rat model

“…Here, the comparable distribution of CSPG4 in human and rat normal tissues renders this system a useful platform for proof-of-concept studies on the safety and toxicology of different biological and immune therapies targeting CSPG4, including those based on the 225.28 clone, the efficacy of which has been extensively described against different solid tumors and in several formulations. [52][53][54][55] By remodeling the tumor microenvironment and harnessing anti-tumor surveillance by immune effector cells such as macrophages, IgE antibodies may overcome tumor-induced immunomodulating forces that restrict the effectiveness of IgGs in tumor-targeted antibody therapy. 15,19,20,56 On the other hand, the faster clearance of IgEs compared to IgGs could represent a challenge in terms of tumor penetration and pharmacokinetic properties and should be further investigated.…”

Targeted Alpha Therapy: Progress in Radionuclide Production, Radiochemistry, and Applications

“…212 Pb-labeled 376.96 monoclonal antibodies were used in mice bearing pancreatic cancer Panc039 xenografts, exhibiting significant uptake and tumor growth inhibition compared to an existing [ 212 Pb]Pb-F3-C25 compound [ 90 ]. 212 Pb-labeled 225.28 antibodies were used in immune-deficient mice bearing SUM159 and 2LMP human triple-negative breast cancer cells, showing high cell uptake and effective inhibition of tumor growth for CSPG4-expressing tumors [ 78 ]. Recently, a variety of low molecular weight ligands were developed and labeled with 212 Pb, and investigated in PSMA(+) PC3 PIP and PSMA(−) PC3 flu flank xenografts.…”