RMC-7977

We propose that concurrent treatment with ONC201 may delay onset of resistance to RAS inhibitor therapy. ClpP activation by dordaviprone/ONC201 suppressed PDAC cell growth and overcame resistance to the RAS(ON) multi-selective inhibitor RMC-7977, providing support for investigating this combination as a potential combination treatment for KRAS-mutant pancreatic cancer.

Moreover, the results also uncover the dynamic process of stabilizer-mediated KRAS-CYPA stabilization and the mechanistic origin of the binding selectivity. This study provides essential molecular-level insights into RMC7977's function and offers a valuable computational framework for evaluating the stabilization effect of ligands targeting the KRAS-CYPA and other challenging PPI systems.

Recent advances in mutation-specific inhibitors (e.g., sotorasib for KRASG12C) have demonstrated clinical efficacy but face limitations in tumor types like PDAC, where KRASG12C mutations are rare. Broad-spectrum pan-RAS inhibitors (e.g., RMC-7977, RMC-6236, ADT-007/ADT-1004) now offer promise by targeting active GTP-bound or nucleotide-free RAS across isoforms and mutations...Challenges remain in achieving a therapeutic index due to RAS's role in normal tissue homeostasis, but tumor-specific drug accumulation and rapid normal tissue recovery may mitigate risks. Ongoing trials are evaluating combination strategies with immunotherapy and chemotherapy, positioning pan-RAS inhibitors as transformative agents for RAS-driven cancers.

Recently, RAS(ON) multi-selective inhibitors like RMC-7977, and the investigational agent daraxonrasib, were described that, in partnership with cyclophilin-A (CYPA), inhibit RAS[GTP] signaling...Moreover, two clinical case studies in patients with NRAS-mutated melanoma treated with daraxonrasib demonstrated clear anti-tumor activity in one patient, but progressive disease in another with co-occurring NRAS and MAP2K1 mutations at baseline. These findings support the potential for daraxonrasib in treatment of patients with NRAS-mutated melanoma, and reveal candidate mechanisms of monotherapy resistance, underscoring the need for combination therapies to improve outcomes.

Further, EGFR inhibitor erlotinib synergized with the RAS(ON) multi-selective inhibitor RMC-7977 in KRASQ61H-mutant PDAC cell lines and in cell lines with highly active EGFR by mitigating ERK rebound activity. KRASi-resistant cell lines featured sustained ERK/MAPK dependence despite decreased ERK activity. Together, these findings enhance the understanding of intrinsic and acquired resistance to KRASi and identify therapeutic vulnerabilities that can potentially be exploited for KRASi combination therapies in pancreatic cancer patients.

Here, we demonstrate that RMC-7977, a preclinical RAS(ON) multi-selective inhibitor representative of the investigational agent daraxonrasib (RMC-6236), was able to elicit potent antitumor immune responses across multiple NRAS-mutant melanoma models. Consistent with these preclinical data, objective clinical responses were observed in two NRAS-mutant melanoma patients treated with daraxonrasib in an ongoing Phase I/Ib clinical trial. Together, these data support the continued clinical evaluation of RAS(ON) multi-selective inhibitors for the treatment of NRAS-mutant melanoma.

Recently, RAS(ON) G12C-selective inhibitors, which bind to the active GTP-bound state of RAS, were described, and elironrasib is undergoing evaluation in multiple clinical trials...Two models reactivated RAS signaling, either via KRASG12C gene amplification or NRASG13R mutation, and were vulnerable to dual inhibition by RAS(ON) G12C-selective and RAS(ON) multi-selective inhibitors, RMC-4998 and RMC-7977...Finally, one model displayed epithelial-mesenchymal transition, loss of RAS dependance, and acquired reliance on cell cycle kinases and proteins associated with DNA damage response. This work highlights KRASG12C-selective inhibitor resistant states that parallel and complement clinical findings and demonstrate that a large subset could be overcome with a RAS(ON) multi-selective inhibitor as a standalone agent or in combination with other therapies.

In murine patient-derived xenograft models of RAS-mutant AML, RMC-7977 was well tolerated and significantly suppressed leukemic burden in combination with gilteritinib or venetoclax. Our findings strongly support clinical investigation of broad-spectrum RAS(ON) inhibition in AML to treat and potentially prevent drug resistance due to activated RAS signaling.

Inactivating oncogenic KRAS reduced serum IL6 and reverted fibroblast STAT3 phosphorylation in mouse lungs; loss of lung fibroblast STAT3 phosphorylation was similarly observed when mice were treated with the pan-RAS inhibitor RMC7977...In human metastasis samples, phosphorylated STAT3 in fibroblasts was similarly more abundant in the lungs than liver. Together, these data point to organ-specific mechanisms driving formation of the PMN and indicate that reprogramming of the microenvironment prior to metastasis might support early dissemination of pancreatic cancer.

Notably, the pan-RAS(ON) inhibitor RMC-7977 effectively reduced viability in NRAS -, KRAS -, and KIT -mutant AM cell lines. Finally, CRISPR screens revealed dependencies selectively essential in AM, including CRKL and SF3B4 , highlighting previously unrecognized vulnerabilities. Our findings emphasize the distinct biology of AM compared to other subtypes of melanoma, provide a valuable resource of models reflective of Latin American ancestry, and identify potential drivers and therapeutic targets.

Here, we deploy high-throughput CRISPR base editing screens to systematically map resistance mutations to three mechanistically distinct KRAS-targeted therapies, including KRAS-G12C(OFF) inhibitor (adagrasib), RAS(ON) G12C-selective tri-complex inhibitor (RMC-4998), and RAS(ON) multi-selective tri-complex inhibitor (RMC-7977). Notably, we identify a recurrent missense mutation in capicua ( Cic ), that promotes resistance to RMC-7977 in vitro and in vivo. Moreover, we show that targeting NFκB signaling in CIC-mutant cells can resensitize them to RAS pathway inhibition and overcome resistance.

We found that KRAS-mutant CRC cell lines were sensitive to the RAS(ON) multiselective RAS inhibitor RMC-7977, given that treatment resulted in RAS-RAF-MEK-ERK pathway inhibition; halted proliferation; and, in some cases, induced apoptosis...Our findings demonstrate the power of reporter-assisted screening together with single-cell analyses for dissecting the complex landscape of therapy resistance. The strategy offers opportunities to develop clinically relevant combinatorial treatments to counteract the emergence of resistant cancer cells.