Therapeutic Targeting of Golgi Phosphoprotein 2 (GOLPH2) with Armed Antibodies: A Preclinical Study of Anti-GOLPH2 Antibody Drug Conjugates in Lung and Colorectal Cancer Models of Patient Derived Xenografts (PDX).

BACKGROUND: Golgi phosphoprotein 2 (GOLPH2) has been shown to be involved in chronic inflammatory processes and carcinogenesis. GOLPH2 is prominently overexpressed in hepatocellular carcinoma, melanoma, glioblastoma, prostate, lung, and colorectal cancer. With a low and tightly regulated expression in non-malignant tissues, GOLPH2 has been proposed as an attractive target for cancer therapy. However, GOLPH2 is predominantly located intracellularly and when situated outside of the cell it is proteolytically cleaved and shed from the cell surface. Until now, GOLPH2 has been regarded as an "undruggable" target. OBJECTIVE: We sought to create antibodies that specifically bind to GOLPH2 overexpressing tumor cells. PATIENTS AND METHODS: Antibodies binding to membranous GOLPH2 despite shedding of the protein were generated from a scFV library screening. These antibodies target the part of GOLPH2 that remains at the cell surface after proteolytic cleavage. These antibodies were then tested in vitro and in vivo. RESULTS: Two candidates (G2-1 and G2-2) showed target specific binding in vitro. Utilizing a tumor array (n = 128 tumors) with G2-2 and a reference antibody, a GOLPH2 expression scoring system was established. Rapid internalization of the antibodies was noted so this was exploited to deliver a toxic payload of pyrrolobenzodiazepine (PBD). In two patient-derived xenograft (PDX)-models, colorectal and lung cancer, the G2-2 antibody drug conjugate (ADC) displayed high efficacy with significant tumor responses (P = 0.001; P = 0.013) and improved survival (P = 0.0001; P = 0.0011) compared with controls. CONCLUSIONS: Treatment with GOLPH2-directed antibodies induces durable responses in colorectal and lung cancer models. With a robust companion assay for GOLPH2 positivity at hand our findings prepare for the translation into a clinical trial.

A pooled analysis of sequential therapies with sorafenib and sunitinib in metastatic renal cell carcinoma.

OBJECTIVE: To evaluate the optimal sequence for the receptor tyrosine kinase inhibitors (rTKIs) sorafenib and sunitinib in metastatic renal cell cancer. METHODS: We performed a retrospective analysis of patients who had received sequential therapy with both rTKIs and integrated these results into a pooled analysis of available data from other publications. Differences in median progression-free survival (PFS) for first- (PFS1) and second-line treatment (PFS2), and for the combined PFS (PFS1 plus PFS2) were examined using weighted linear regression. RESULTS: In the pooled analysis encompassing 853 patients, the median combined PFS for first-line sunitinib and 2nd-line sorafenib (SuSo) was 12.1 months compared with 15.4 months for the reverse sequence (SoSu; 95% CI for difference 1.45-5.12, p = 0.0013). Regarding first-line treatment, no significant difference in PFS1 was noted regardless of which drug was initially used (0.62 months average increase on sorafenib, 95% CI for difference -1.01 to 2.26, p = 0.43). In second-line treatment, sunitinib showed a significantly longer PFS2 than sorafenib (average increase 2.66 months, 95% CI 1.02-4.3, p = 0.003). CONCLUSION: The SoSu sequence translates into a longer combined PFS compared to the SuSo sequence. Predominantly the superiority of sunitinib regarding PFS2 contributed to the longer combined PFS in sequential use.

Targeted therapeutic approach for an anaplastic thyroid cancer in vitro and in vivo.

Anaplastic thyroid carcinoma (ATC) is among the most aggressive human malignancies, being responsible for the majority of thyroid cancer-related deaths. Despite multimodal therapy including surgery, chemotherapy, and radiotherapy, the outcome of ATC is poor. The human ATC cell line MB1, derived from tumor tissue of a 57-year-old man with thyroid cancer and pronounced neutrophilia, was established from surgically excised tumor tissue. The karyotype of the cell line shows many chromosomal abnormalities. Preclinical investigations have shown antitumor activity and effectiveness of the BRAF kinase inhibitor Sorafenib and the proteasome inhibitor Bortezomib. After establishment of the MB1 cell line these agents were applied in vitro and, showing activity in a cell culture model, were also used for in vivo treatment. Sorafenib had some clinical effect, namely normalization of leucocytosis, but had no sustained impact on subsequent tumor growth and development of distant metastasis. Molecular diagnostics of the tumor demonstrated no BRAF mutations in exons 11 and 15 concordant with a rather modest effect of Sorafenib on MB1 cell growth. Clinical benefit was seen with subsequent bortezomib therapy inducing a temporary halt to lymph node growth and a progression-free interval of 7 weeks. Our observations together with previous data from preclinical models could serve as a rationale for selecting those patients suffering from ATC most likely to benefit from targeted therapy. A prospective controlled randomized trial integrating kinase and proteasome inhibitors into a therapeutic regime for ATC is warranted.