LK-1: an investigational therapy targeting hCG-β in metastatic breast, bladder, ovarian, and cervical cancers.

Human chorionic gonadotropin beta (hCG-β), while primarily recognized for its role in pregnancy, has also been implicated in poor prognosis for cancer patients over the past several decades. Targeting dysregulated hCG-β production by cancer cells may prove an effective way to combat tumor growth. We propose that targeting hCG-β production using antisense phosphorodiamidate morpholino oligomers (PMO) technology could provide a precise and effective strategy for lowering hCG-β levels. This method may offer enhanced specificity and the ability to modulate hCG-β expression directly at the mRNA transcript level. Here, we tested multiple PMO sequences targeted against hCG-β mRNA transcripts at various regions to ensure optimal sequence specificity and effective knockdown. We used cell viability assays, pregnancy test strips, and ELISA assays to determine knockdown by each PMO sequence to initially screen PMO sequences for identifying the most effective candidates. Of the sequences evaluated using ELISA, one demonstrated demonstrated effective knockdown at 0.5 µM and three at 1 µM. The remaining sequences required high PMO concentrations to observe a phenotype, and some did not produce measurable hCG knockdown under the conditions tested. Across nineteen PMO sequences tested in eight different cell lines, seven consistently reduced cell viability at 2-4 µM, whereas the remaining sequences showed variable or minimal effects. From the initial screen we identified the best PMO sequence, termed LK-1, for further analysis. We demonstrated that LK-1 is effective at significantly reducing hCG-β expression as measured both by western blot and ELISA assays. LK-1 treatment also showed significant reduction in cancer cell viability, reduce clonogenicity in colony formation assays, increased tumor cell death, and reduced invasion via wound healing assay in several cancer cell lines. We also showed that LK-1 is effective at reducing tumor formation in 3D spheroids. Combined, these findings suggest that targeting hCG-β production with morpholino-based therapy may represent a promising approach for cancers expressing this protein.