Solitomab, an epithelial cell adhesion molecule/CD3 bispecific antibody (BiTE), is highly active against primary chemotherapy‐resistant ovarian cancer cell lines in vitro and fresh tumor cells ex vivo

Abstract

Background Solitomab is a novel bispecific single-chain antibody which targets EpCAM on tumor cells and also contains a CD3 binding region. We evaluated in vitro activity of solitomab against primary chemo-resistant epithelial ovarian carcinoma cell lines as well as malignant cells in ascites. Methods EpCAM expression was evaluated by flow cytometry in 5 primary ovarian cancer cell lines and 42 fresh ovarian tumor cell cultures from ascites of patients with mainly advanced or recurrent chemo-resistant disease. The potential activity of solitomab against EpCAM + tumor cells was evaluated by flow-cytometry, proliferation and 4-hr chromium-release cell-mediated cytotoxicity assays. Results Expression of EpCAM was detected by flow cytometry in approximately 80% of fresh ovarian tumors and primary ovarian tumor cell lines tested. EpCAM + chemo-resistant cell lines were found resistant to NK or T-cell-mediated killing after exposure to peripheral blood lymphocytes (PBL) in 4-hour chromium-release assays (mean killing ± SEM, 3.6 ± 0.7% after incubation of EpCAM + cell lines with control BiTE). In contrast, after incubation with solitomab, EpCAM + chemo-resistant cells became highly sensitive to T cell cytotoxicity (mean killing ± SEM of 28.2 ± 2.05%; P < 0.0001) by PBL. Ex vivo incubation of autologous tumor associated lymphocytes (TAL) with EpCAM expressing malignant cells in ascites with solitomab, resulted in a significant increase in T-cell activation markers, and a reduction in number of viable ovarian tumor cells in ascites (P < 0.001). Conclusions Solitomab may represent a novel, potentially effective agent for treatment of chemo-resistant ovarian cancer overexpressing EpCAM.

Polymerase ε (POLE) ultra-mutated tumors induce robust tumor-specific CD4+ T cell responses in endometrial cancer patients

“…Importantly, a high load of somatic mutations has been recently associated with a survival benefit from immune checkpoint abrogation in human tumors [15]. These data combined with our findings and the recent discovery that POLE mutated tumors display prominent immune infiltrate in vivo [19], suggest but not prove that POLE ultra-mutated tumors, similar to melanoma and lung cancer patients with high mutation burden, may potentially strongly benefit from the use of novel immunotherapeutic approaches based on blocking immune check-points antibodies (i.e., anti-CTLA4-ipilimumab, anti-PD1-nivolumab, Bristol Meyers Squibb, Wallingford, CT). Additional studies will be necessary to validate this hypothesis.…”

“…All assays were carried out in triplicate wells. In additional experiments tumor-lysate stimulated CD4+ T cells or unstimulated PBL from POLE mutated vs POLE wild type patients were stained with carboxyfluorescein succinimidyl ester (CFSE) (CellTrace CFSE Cell Proliferation Kit, Invitrogen, Carlsbad, CA) at a working concentration of 10 micromolar as previously described [19] in the absence of IL2. The CFSE labeled cells were plated and cultured in the presence of tumor lysate-pulsed or PHA-activated peripheral blood lymphocytes lysate-pulsed autologous DC or LCL for 5 to 6 days.…”

Immunotherapy of hepatocellular carcinoma using chimeric antigen receptors and bispecific antibodies

“…In addition to liver cancers, anti- EpCAM bispecific antibodies have been tested against some other tumors [9, 33, 36, 37, 87, 88, 97, 98]. Ex vivo, incubation of autologous tumor-associated lymphocytes with EpCAM(+) cancer cells in the presence of Solitomab led to activation and proliferation of effector cells and diminished the number of target cells including uterine serous papillary carcinoma [9], and Uterine and ovarian carcinosarcomas [33, 37]. Furthermore, intraperitoneal administration of catumaxomab, an IgG-based antibody with monovalent specificity against EpCAM and CD3 (fig 2C), led to regression of breast cancer-induced liver metastases [87].…”

Leveraging immunotherapy for the treatment of gynecologic cancers in the era of precision medicine

“…This strategy has been demonstrated to be effective in xenograft models of human colorectal and ovarian cancer [33]. More recently, in preclinical models of ovarian carcinoma, a novel EpCAM-CD3 BiTE solitomab has demonstrated significant activity against human ovarian tumor cells in vitro and ex vivo [34, 35]. …”