Creating MHC-restricted neoantigens with covalent inhibitors that can be targeted by immune therapy

Intracellular oncoproteins can be inhibited with targeted therapy, but responses are not durable. Immune therapies can be curative, but most oncogene-driven tumors are unresponsive to these agents. Fragments of intracellular oncoproteins can act as neoantigens presented by the major histocompatibility complex (MHC) but recognizing minimal differences between oncoproteins and their normal counterparts is challenging. We have established a platform technology that exploits hapten-peptide conjugates generated by covalent inhibitors to create distinct neoantigens that selectively mark cancer cells. Using the FDA-approved covalent inhibitors sotorasib and osimertinib, we developed “HapImmuneTM” antibodies that bind to drug-peptide conjugate/MHC complexes but not to the free drugs. A HapImmuneTM-based bispecific T cell engager selectively and potently kills sotorasib-resistant lung cancer cells upon sotorasib treatment. Notably, it is effective against KRASG12C mutant cells with different HLA supertypes, HLA-A*02 and A*03/11, suggesting loosening of MHC restriction. Our strategy creates targetable neoantigens by design, unifying targeted and immune therapies.

Cancer Discov CD-22-1074


Combined Inhibition of SHP2 and CXCR1/2 Promotes Anti-Tumor T Cell Response in NSCLC


Clinical trials of SHP2 inhibitors (SHP2i) alone and in various combinations are ongoing for multiple tumors with over-activation of the RAS/ERK pathway. SHP2 plays critical roles in normal cell signaling; hence, SHP2is could influence the tumor microenvironment. We found that SHP2i treatment depleted alveolar and M2-like macrophages and promoted B and T lymphocyte infiltration in Kras- and Egfr-mutant non-small cell lung cancer (NSCLC). However, treatment also increased intratumor gMDSCs via tumor-intrinsic, NF-kB-dependent production of CXCR2 ligands. Other RAS/ERK pathway inhibitors also induced CXCR2 ligands and gMDSC influx in mice, and CXCR2 ligands were induced in tumors from patients on KRASG12C-inhibitor trials. Combined SHP2(SHP099)/CXCR1/2(SX682) inhibition depleted a specific cluster of S100a8/9high gMDSCs, generated Klrg1+ CD8+ effector T cells with a strong cytotoxic phenotype but expressing the checkpoint receptor NKG2A, and enhanced survival in Kras-and Egfr-mutant models. Our results argue for testing RAS/ERK pathway/CXCR1/2/NKG2A inhibitor combinations in NSCLC patients.


Our study shows that inhibiting the SHP2/RAS/ERK pathway triggers NF-kB-dependent up-regulation of CXCR2 ligands and recruitment of S100A8high gMDSCs, which suppress T cells in NSCLC. Combining SHP2 and CXCR2 inhibitors blocks this gMDSC immigration, resulting in enhanced Th1 polarization, induction of CD8+ KLRG1+ effector T cells with high cytotoxic activity and improved survival in multiple NSCLC models.

SHP2 Inhibition Abrogates Adaptive Resistance to KRASG12C-Inhibition and Remodels the Tumor Microenvironment of KRAS-Mutant Tumors


KRAS is the most frequently mutated oncogene in human cancer, and KRAS inhibition has been a longtime therapeutic goal. Recently, inhibitors (G12C-Is) that bind KRASG12C-GDP and react with Cys-12 were developed. Using new affinity reagents to monitor KRASG12C activation and inhibitor engagement, we found that, reflecting its action upstream of SOS1/2, SHP2 inhibitors (SHP2-Is) increased KRAS-GDP occupancy, enhancing G12C-I efficacy. SHP2-Is abrogated feedback signaling by multiple RTKs and blocked adaptive resistance to G12C-Is in vitro, in xenografts, and in syngeneic KRASG12Cmutant pancreatic ductal adenocarcinoma (PDAC) and non-small cell lung cancer (NSCLC) models. Biochemical analysis revealed enhanced suppression of ERK-, MYC-, anti-apoptotic-, and cell-cycle genes, and increased pro-apoptotic gene expression in tumors from combination-treated mice. SHP2-I/G12C-I also evoked favorable changes in the immune microenvironment, decreasing myeloid suppressor cells, increasing CD8+ T cells, and sensitizing tumors to PD-1 blockade. Experiments using cells expressing inhibitor-resistant SHP2 showed that SHP2 inhibition in PDAC cells is required for tumor regression and remodeling of the immune microenvironment, but also revealed direct inhibitory effects on angiogenesis resulting in decreased tumor vascularity. Our results demonstrate that SHP2-I/G12C-I combinations confer a substantial survival benefit in PDAC and NSCLC and identify additional combination strategies for enhancing the efficacy of G12C-Is.

[preprint posted on bioRxiv 2020 May 31]

SHP2 Inhibition Prevents Adaptive Resistance to MEK Inhibitors in Multiple Cancer Models

The RAS/ERK MAP kinase pathway is aberrantly activated in a large percentage of human cancers, and promotes malignant behavior.  Inhibitors of MEK, one of the key intermediates in this pathway, have had limited utility in the clinic, often due to the rapid development of “intrinsic resistance.”  Intrinsic resistance is due to up regulation of multiple growth factor receptors and their ligands, and previous work by the lab and by others has shown that is required for RAS activation by these receptors.  Here we found that combining MEK and SHP2 inhibitors shows broad efficacy against a wide range of malignancies, and also that SHP2 inhibitors as single agents can antagonize certain types of RAS mutations (fast cycling mutants).

SHP2 Inhibition Prevents Adaptive Resistance to MEK Inhibitors in Multiple Cancer Models.
Cancer Discov. 2018 Oct;8(10):1237-1249.



Vitamin C in Stem Cell Reprogramming and Cancer

Mutations of one copy of TET2, whose protein product promotes DNA (and RNA) hydroxymethylation (and eventually, DNA and RNA de-methylation, are commonly associated with myelodyspastic syndromes (MDS) and acute myeloid leukemia, among other hematopoietic neoplasms. Previous work had suggested that Vitamin C, an essential co-factor of TET2, can promote TET2 activation as well.  We found that high dose vitamin C, acting via residual TET2 and TET3, had potent anti-neoplastic effects in mouse and human models of MDS/AML. Molecular analysis confirmed that this treatment promotes demethylation of key leukemia-associated genes, including base excision repair genes. The latter result suggested that PARP inhibitors might further increase Vitamin C efficacy, which we also demonstrated.

Vitamin C in Stem Cell Reprogramming and Cancer
Trends Cell Biol. 2018 Sep;28(9):698-708.