Elevation Oncology, a clinical stage biopharmaceutical company focused on the development of precision medicines for patients with genomically defined cancers, announced today the presentation by its collaborators in the Marc Ladanyi lab at Memorial Sloan Kettering (MSK) of further preclinical data on the specific inhibition of NRG1 fusion-induced tumorigenesis and signaling by seribantumab, a HER3 monoclonal antibody, at the American Association of Cancer Research Virtual Annual Meeting 2021. These data in patient-derived xenograft (PDX) models of NRG1 fusion-positive pancreatic and cholangiocarcinoma build on earlier studies generated in lung and ovarian NRG1 fusion PDX models,, and further support the mechanistic rationale for the Phase 2 CRESTONE study for patients with solid tumors of any origin harboring an NRG1 gene fusion. The CRESTONE study is currently enrolling at sites across the United States.
"Here we observed that NRG1 fusions activated HER3 and downstream signaling mediators such as AKT in a pancreatic cell line," said Igor Odintsov, MD, Research Fellow at MSK and lead author of the poster presentation. "Treatment with seribantumab was able to inhibit phosphorylation of the activated HER3 and AKT in the same cell line, and subsequent treatment of an APP-NRG1 fusion-positive pancreatic PDX model with seribantumab robustly inhibited tumor growth at clinically achievable doses."
Regressions were observed in all mice treated with 10 mg/kg BIW seribantumab, equivalent to a clinical dose of 2.6 g seribantumab in humans by allometric scaling. As in prior analysis in lung and ovarian NRG1 fusion PDX models, the pan-ERBB inhibitor afatinib was used as an active control in this pancreatic PDX model. No regression was observed in pancreatic PDX tumors treated with afatinib at 5 mg/kg QD.
NRG1 fusions have been identified in a variety of solid tumors, including lung, pancreatic, gallbladder, breast, ovarian, colorectal, neuroendocrine, cholangiocarcinomas, and sarcomas. Current data suggest that NRG1 fusions are predominantly mutually exclusive with other known driver alterations and are therefore considered to be the primary driver of the tumor's growth and proliferation.
"The rarity of competing oncogenic drivers in tumors driven by an NRG1 fusion presents a strong biological rationale for use of a targeted anti-HER3 monotherapy approach across tumor types. This approach is reflected in the design of our Phase 2 CRESTONE study as a tumor-agnostic study of monotherapy seribantumab with pre-defined exclusion of patients whose tumors harbor multiple actionable driver alterations," said Shawn M. Leland, PharmD, RPh, Founder and Chief Executive Officer of Elevation Oncology "In rare instances when multiple actionable driver alterations are identified in the same tumor, we believe there may be a similar biological rationale for addressing each driver alteration through combinations of agents targeted to each individual alteration, rather than the traditional combinations with chemotherapy. We are excited to report early results from preclinical exploration of this hypothesis, and look forward to continued investigation of new treatment paradigms informed by comprehensive genomic profiling of tumors."
"We utilized an RBPMS-NRG1 fusion cholangiocarcinoma PDX model that also contained mutations in both ERBB4 and IDH1," continued Dr. Odintsov. "While treatment with monotherapy seribantumab or afatinib in this model produced mixed results, by applying a triple combination of seribantumab with afatinib to target the entire ERBB family, and AG-120 to target the IDH1 mutation, we were able to achieve regressions in the majority of tumors. This suggests that tumors harboring multiple oncogenic drivers may benefit from combination therapy that addresses the contribution of each genomic alteration in disease progression."
In totality, the data reported support the use of monotherapy seribantumab to treat GI and other cancers that are uniquely driven by an NRG1 fusion in the ongoing Phase 2 CRESTONE study.
