Targeting galectin-3 with a high-affinity antibody for inhibition of high-grade serous ovarian cancer and other MUC16/CA-125-expressing malignancies

Abstract

The lectin, galectin-3 (Gal3), has been implicated in a variety of inflammatory and oncogenic processes, including tumor growth, invasion, and metastasis. The interactions of Gal3 and MUC16 represent a potential targetable pathway for the treatment of MUC16-expressing malignancies. We found that the silencing of Gal3 in MUC16-expressing breast and ovarian cancer cells in vitro inhibited tumor cell invasion and led to attenuated tumor growth in murine models. We therefore developed an inhibitory murine monoclonal anti–Gal3 carbohydrate-binding domain antibody, 14D11, which bound human and mouse Gal3 but did not bind human Galectins-1, -7, -8 or -9. Competition studies and a docking model suggest that the 14D11 antibody competes with lactose for the carbohydrate binding pocket of Gal3. In MUC16-expressing cancer cells, 14D11 treatment blocked AKT and ERK1/2 phosphorylation, and led to inhibition of cancer cell Matrigel invasion. Finally, in experimental animal tumor models, 14D11 treatment led to prolongation of overall survival in animals bearing flank tumors, and retarded lung specific metastatic growth by MUC16 expressing breast cancer cells. Our results provide evidence that antibody based Gal3 blockade may be a viable therapeutic strategy in patients with MUC16-expressing tumors, supporting further development of human blocking antibodies against Gal3 as potential cancer therapeutics.

ImmunoPET of Ovarian and Pancreatic Cancer with AR9.6, a Novel MUC16-Targeted Therapeutic Antibody

“…The therapeutic mechanism of muAR9.6 distinguishes it from other MUC16-targeted antibodies, including those reported from our laboratories (10,13,15,16,24,25,31,32). Motivated by its novelty, we set out to validate the in vitro cell binding of muAR9.6 and explore the in vivo behavior of a 89 Zr-labeled variant of the antibody in preclinical tumor models.…”

“…However, Reinartz et al have shown that SKOV3 cells have very low levels of MUC16 transcript (mRNA), and though they reported no binding of anti-CA125 antibodies to SKOV3 cells, Felder et al reported marginal binding of OC125-like MUC16-binding antibodies to SKOV3 cells via flow cytometry. Plausibly, alternative splicing or post-translational modifications may be causing the AR9.6 epitope to be expressed on SKOV3 cells, leading to marginal binding to this cell line that is otherwise considered MUC16-negative (14,32). In our hands, using muAR9.6 as the primary antibody for Western blotting of SKOV3 cell lysate revealed binding of the antibody to a low molecular weight band observed in the other MUC16-positive cell lines such as OVCAR3, Capan-2, S2-2028 and T3M-4 (Figure S3).…”

Targeting interactions between the Galectin-3 intrinsically disordered and structured domains based on long time-scale accelerated molecular dynamics

“…Studies to inhibit Galectin-3 classically focused on blocking the binding of carbohydrate substrates to the recognition domain. Reagents that are based on such a mechanism of action include carbohydrate mimetics (14), peptides that bind to the CRD (42), and, recently, function blocking antibodies (60). However, because the NTD-CTD interaction appears to be essential for the extracellular activity of Galectin-3, the inhibition of this interaction may afford an alternative approach.…”

“…Although studies to inhibit Galectin-3 classically focused on blocking the binding of carbohydrate substrates to the recognition domain ( 14), ( 42), (58), galactomannins (59) and PTX008, a calixarene (50) may also target the NTD-CRD interaction. PTX008 contacts V202, K210, V211 and A216 located in the F-face of the CRD, which are also contacted by peptide-3 in our study.…”

Galectins in Cancer and the Microenvironment: Functional Roles, Therapeutic Developments, and Perspectives

“…Neutralizing antibodies are commonly used to block protein functions. Stasenko et al showed that invasion and proliferation were suppressed in high-grade serous ovarian cancer, and showed improved overall survival, in response to treatment with an anti-Gal-3 antibody [ 158 ]. Evidence shows that neutralizing antibodies may partially suppress the inhibition of lactose treatment [ 159 ].…”