Development and preclinical evaluation of cixutumumab drug conjugates in a model of insulin growth factor receptor I (IGF-1R) positive cancer

Overexpression of insulin growth factor receptor type 1 (IGF-1R) is observed in many cancers. Antibody drug conjugates (ADCs) with PEGylated maytansine (PEG6-DM1) show promise in vitro. We developed PEG6-DM1 ADCs with low and high drug to antibody ratios (DAR) using an anti-IGF-1R antibody cixutumumab (IMC-A12). Conjugates with low (cixutumumab-PEG6-DM1-Low) and high (cixutumumab-PEG6-DM1-High) DAR as 3.4 and 7.2, respectively, were generated. QC was performed by UV spectrophotometry, HPLC, bioanalyzer, and biolayer-interferometry. We compared the in vitro binding and internalization rates of the ADCs in IGF-1R-positive MCF-7/Her18 cells. We radiolabeled the ADCs with 111In and used microSPECT/CT imaging and ex vivo biodistribution to understand their in vivo behavior in MCF-7/Her18 xenograft mice. The therapeutic potential of the ADC was studied in vitro and in mouse xenograft. Internalization rates of all ADCs was high and increased over 48 h and EC50 was in the low nanomolar range. MicroSPECT/CT imaging and ex vivo biodistribution showed significantly lower tumor uptake of 111In-cixutumumab-PEG6-DM1-High compared to 111In-cixutumumab-PEG6-DM1-Low and 111In-cixutumumab. Cixutumumab-PEG6-DM1-Low significantly prolonged the survival of mice bearing MCF-7/Her18 xenograft compared with cixutumumab, cixutumumab-PEG6-DM1-High, or the PBS control group. Cixutumumab-PEG6-DM1-Low ADC was more effective. The study highlights the potential utility of cixutumumab-ADCs as theranostics against IGF-1R positive cancers.

Prospective biomarker validation trial evaluating the prognostic role of the combined expression of phospho-insulin growth factor receptor-1 and matrilysin in KRAS (exon 2) wild-type (WT) metastatic colorectal cancer (mCRC) patients treated with FOLFOX-6 plus panitumumab as first-line therapy [PULSE trial (GEMCAD 09-03)].

583 Background: Matrilysin can activate phospho-insulin growth factor receptor-1 (pIGF-1R) through IGFBP-3 degradation, releasing IGF-1. Matrilysin per se has shown poor prognosis in mCRC and the co-expression of matrilysin and pIGF-1R (double positivity, DP) correlates with poor prognosis in WT KRAS refractory patients (pts) treated with anti-EGFR in retrospective analyses. We performed a prospective clinical trial in WT KRAS (exon 2) pts, treated with FOLFOX plus panitumumab in first-line therapy to validate those findings. Methods: Positive cases were defined by immunohistochemistry as those with moderate or strong intensity (++/+++) and > 70% expression for both matrilysin and p-IGF-1R (antibody anti-pY1316). The primary end-point was progression-free survival (PFS). Seventy-eight pts and 56 events were required to have an 80% power to detect a difference in median PFS of 6 months (two-sided p< 0.05). Results: We screened 196 mCRC pts in 24 centers between Nov/2010 and Apr/2013 and 78 pts met inclusion criteria (42 non-DP and 36 DP). Median follow-up was 23 months. There were no differences in baseline characteristics [age, sex, liver metastases, lactate dehydrogenase (LDH) levels, performance status and BRAF mutational status] between both groups. There were no differences in the number of FOLFOX-6 and panitumumab cycles received. Cutaneous toxicity was more frequent in DP pts (p = 0.035). Response rate was 80.5% in non-DP and 72.2% in DP patients (p = 0.37). Median PFS (95% CI) was 7.4 months (95%CI 5.2-13.3) in non-DP and 9.6 months (95% CI 6.7-17.5, p = 0.15) in DP patients. Median overall survival was 19.8 months (11.5-26.3) in non-DP pts and 39.1 months (26-NE, p = 0.071) in DP pts. Adjusted HR for PFS was 0.68 (95% CI 0.41-1.12). Adjusted analysis for OS was 0.50 (95% CI 0.27-0.90). Conclusions: We found that co-expression of matrilysin and pIGF-1R is a novel strong prognostic biomarker of survival benefit in mCRC KRAS WT pts treated in first-line with FOLFOX-6 plus panitumumab. Clinical trial information: NCT01288339.

The Motile Breast Cancer Phenotype Roles of Proteoglycans/Glycosaminoglycans

The consecutive stages of cancer growth and dissemination are obligatorily perpetrated through specific interactions of the tumor cells with their microenvironment. Importantly, cell-associated and tumor microenvironment glycosaminoglycans (GAGs)/proteoglycan (PG) content and distribution are markedly altered during tumor pathogenesis and progression. GAGs and PGs perform multiple functions in specific stages of the metastatic cascade due to their defined structure and ability to interact with both ligands and receptors regulating cancer pathogenesis. Thus, GAGs/PGs may modulate downstream signaling of key cellular mediators including insulin growth factor receptor (IGFR), epidermal growth factor receptor (EGFR), estrogen receptors (ERs), or Wnt members. In the present review we will focus on breast cancer motility in correlation with their GAG/PG content and critically discuss mechanisms involved. Furthermore, new approaches involving GAGs/PGs as potential prognostic/diagnostic markers or as therapeutic agents for cancer-related pathologies are being proposed.