Abstract 3123: Targeting SHP2 and RAS MAPK pathway in neuroblastoma

Abstract

Abstract Introduction: Neuroblastoma (NB), the most common pediatric extra-cranial solid tumor, recurs in >50% of patients who present with metastases. Strategies to treat relapsed NB, which is often fatal, include targeting relapse-specific signaling pathways. Recently, sequencing studies have revealed that 78% of mutations detected in relapse samples are predicted to activate the RAS-MAPK pathway, suggesting there may be opportunities to pharmacologically target this pathway to treat recurrent NB. Experimental Design: Our lab previously reported that the PTPN11-encoded tyrosine phosphatase SHP2 is an activator of the RAS pathway, and pharmacologic inhibition of SHP2 inhibited glioblastoma growth in vivo. To determine whether inhibiting SHP2 in NB would impact tumor growth we treated a panel of NB cells with diverse genetic backgrounds, including mutations in NRAS, with different SHP2 inhibitors (SHP099 and II-B08) alone and in combination with additional drugs that target RAS-MAPK signaling. Results: In comparison to NB cell lines harboring endogenous NRAS mutations (NRASmt), cells with NRAS wild-type (NRASwt) were more sensitive to SHP2 inhibitors. In addition, NRASwt cells engineered to overexpress NRASmt were more resistant to SHP099 than cells with endogenous or overexpressed NRASwt, as demonstrated by higher levels of proliferation, increased survival, and diminished apoptosis. Furthermore, SHP099 effectively inhibited SHP2 in both NRASwt and NRASmt cells, but only failed to inactivate the downstream RAS effector ERK1/2 in NRASmt cells, suggesting that SHP099 treatment alone is ineffective in cells harboring NRAS mutations. To determine whether SHP099 resistance in NRASmt cells could be overcome with combination strategies, sensitive and resistant NB cells were treated with SHP2 inhibitors alone or in combination with other RAS-MAPK pathway inhibitors (vemurafenib, trametinib and ulixertinib). Interestingly, in comparison to SHP099 or II-B08 alone, all three combinations significantly reduced survival and IC50 values in both NRASwt and NRASmt cells. Using the Bliss independence model we determined all three combinations were synergistic. Conclusions: Our studies demonstrate that NRAS mutations are associated with resistance to SHP2 inhibitors, and that in certain tumors, based on the genetic status of RAS-MAPK-SHP2 signaling components, combinations of drugs targeting this pathway could be effective strategies for relapsed NB. Citation Format: Ivette Valencia-Sama, Teresa Adderley, Lynn Kee, Gabriella Christopher, Yoshihito Kano, Michael Ohh, Meredith Irwin. Targeting SHP2 and RAS MAPK pathway in neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3123.