An allosteric pan-TEAD inhibitor blocks oncogenic YAP/TAZ signaling and overcomes KRAS G12C inhibitor resistance.

The Hippo pathway is a key growth control pathway that is conserved across species. The downstream effectors of the Hippo pathway, YAP (Yes-associated protein) and TAZ (transcriptional coactivator with PDZ-binding motif), are frequently activated in cancers to drive proliferation and survival. Based on the premise that sustained interactions between YAP/TAZ and TEADs (transcriptional enhanced associate domain) are central to their transcriptional activities, we discovered a potent small-molecule inhibitor (SMI), GNE-7883, that allosterically blocks the interactions between YAP/TAZ and all human TEAD paralogs through binding to the TEAD lipid pocket. GNE-7883 effectively reduces chromatin accessibility specifically at TEAD motifs, suppresses cell proliferation in a variety of cell line models and achieves strong antitumor efficacy in vivo. Furthermore, we uncovered that GNE-7883 effectively overcomes both intrinsic and acquired resistance to KRAS (Kirsten rat sarcoma viral oncogene homolog) G12C inhibitors in diverse preclinical models through the inhibition of YAP/TAZ activation. Taken together, this work demonstrates the activities of TEAD SMIs in YAP/TAZ-dependent cancers and highlights their potential broad applications in precision oncology and therapy resistance.

Stabilizing a Tubulysin Antibody-Drug Conjugate To Enable Activity Against Multidrug-Resistant Tumors.

The tubulysins are promising anticancer cytotoxic agents due to the clinical validation of their mechanism of action (microtubule inhibition) and their particular activity against multidrug-resistant tumor cells. Yet their high potency and subsequent systemic toxicity make them prime candidates for targeted therapy, particularly in the form of antibody-drug conjugates (ADCs). Here we report a strategy to prepare stable and bioreversible conjugates of tubulysins to antibodies without loss of activity. A peptide trigger along with a quaternary ammonium salt linker connection to the tertiary amine of tubulysin provided ADCs that were potent in vitro. However, we observed metabolism of a critical acetate ester of the drug in vivo, resulting in diminished conjugate activity. We were able to circumvent this metabolic liability with the judicious choice of a propyl ether replacement. This modified tubulysin ADC was stable and effective against multidrug-resistant lymphoma cell lines and tumors.

Distinct apoptotic signaling characteristics of the anti-CD40 monoclonal antibody dacetuzumab and rituximab produce enhanced antitumor activity in non-Hodgkin lymphoma.

PURPOSE: Individually targeting B-cell antigens with monoclonal antibody therapeutics has improved the treatment of non-Hodgkin lymphoma (NHL). We examined if the antitumor activity of rituximab, CD20-specific antibody, could be improved by simultaneously targeting CD40 with the humanized monoclonal antibody dacetuzumab (SGN-40). EXPERIMENTAL DESIGN: Dacetuzumab was dosed with rituximab to determine the in vivo activity of this combination in a subcutaneous Ramos xenograft model of non-Hodgkin lymphoma (NHL). The effect of dacetuzumab on rituximab antibody-dependent cell mediated-cytotoxicity (ADCC), antiproliferative, and apoptotic activities were evaluated in vitro using NHL cell lines. Western blotting and flow cytometry were used to contrast the signaling pathways activated by dacetuzumab and rituximab in NHL cells. RESULTS: The dacetuzumab-rituximab combination had significantly improved antitumor activity over the equivalent dose of rituximab in the Ramos xenograft model (P = 0.0021). Dacetuzumab did not augment rituximab-mediated ADCC activity; however, these antibodies were additive to synergistic in cell-proliferation assays and produced increased apoptosis in combination. Rituximab signaling downregulated BCL-6 oncoprotein in a cell line-specific manner, whereas dacetuzumab strongly downregulated BCL-6 in each cell line. Dacetuzumab induced expression of the proapoptotic proteins TAp63 and Fas, whereas rituximab did not affect basal expression of either protein. Finally, rituximab partially blocked dacetuzumab-mediated upregulation of the prosurvival protein BCL-x(L). CONCLUSIONS: Targeting CD40 with dacetuzumab enhanced the antitumor activity of rituximab in cell line and xenograft NHL models. The distinct but complementary apoptotic signal transduction profiles of dacetuzumab and rituximab are an important mechanism behind the improved activity of this combination.

CD40 pathway activation status predicts response to CD40 therapy in diffuse large B cell lymphoma.

The primary function of B cells, critical components of the adaptive immune response, is to produce antibodies against foreign antigens, as well as to perform isotype class switching, which changes the heavy chain of an antibody so that it can interact with different repertoires of effector cells. CD40 is a member of the tumor necrosis factor superfamily of cell surface receptors that transmits survival signals to B cells. In contrast, in B cell cancers, stimulation of CD40 signaling results in a heterogeneous response in which cells can sometimes undergo cell death in response to treatment, depending on the system studied. We found an association between sensitivity to CD40 stimulation and mutation of the tumor suppressor p53 in a panel of non-Hodgkin's lymphoma cell lines. Consistent with p53's tumor suppressor role, we found that higher levels of intrinsic DNA damage and increased proliferation rates, as well as higher levels of BCL6, a transcriptional repressor proto-oncogene, were associated with sensitivity to CD40 stimulation. In addition, CD40 treatment-resistant cell lines were sensitized to CD40 stimulation after the introduction of DNA-damaging agents. Using gene expression analysis, we also showed that resistant cell lines exhibited a preexisting activated CD40 pathway and that an mRNA expression signature comprising CD40 target genes predicted sensitivity and resistance to CD40-activating agents in cell lines and mouse xenograft models. Finally, the gene signature predicted tumor shrinkage and progression-free survival in patients with diffuse large B cell lymphoma treated with dacetuzumab, a monoclonal antibody with partial CD40 agonist activity. These data show that CD40 pathway activation status may be useful in predicting the antitumor activity of CD40-stimulating therapeutic drugs.