Summary
Current evidence for KRAS G12D inhibitors in pancreatic ductal adenocarcinoma (PDAC) is primarily preclinical or derived from early-phase clinical data, with no published phase III efficacy results for G12D-specific agents yet. Preclinical models indicate that MRTX1133 induces deep tumor regressions but faces acquired resistance via Kras amplification and mesenchymal transition [2]. The pan-RAS inhibitor daraxonrasib demonstrated a doubling of median overall survival (13.2 vs 6.6 months) in the phase III RASolute-302 trial for metastatic PDAC, establishing a new standard in the second-line setting [5]. Early clinical data for selective G12D inhibitors including RNK08594, GFH375, and DN022150 are encouraging but remain preliminary [4].
Evidence
**Preclinical Efficacy of MRTX1133**: In KPC mouse models, the KRASG12D inhibitor MRTX1133 yielded deep tumor regressions; however, resistance emerged accompanied by amplifications of Kras, Yap1, Myc, Cdk6, and Abcb1a/b [2]. Combination with chemotherapy improved tumor control in these models [2].
**Resistance Mechanisms**: Resistance to KRASG12D inhibition is associated with epithelial-to-mesenchymal transition, PI3K-AKT-mTOR signaling, and reactivation of the unfolded protein response (UPR) via the MEK/ERK pathway [2][3]. Mesenchimal and basal-like cell states showed increased response to KRAS inhibition compared to classical states in preclinical models [2].
**Combination Strategies**: Nimotuzumab synergized with HRS-4642 (a novel KRASG12D inhibitor) to reverse resistance mediated by MEK/ERK/UPR axis reactivation in vitro and in vivo [3]. Horizontal combinations of HRS-4642 with adebrelimab or a Nectin-4-targeted ADC are being evaluated [5].
**Clinical Trial Landscape**: Early clinical data for KRASG12D-selective inhibitors RNK08594, GFH375, and DN022150 were presented at ASCO 2026, suggesting potential utility in PDAC [4]. Acquired resistance to HRS-4642 was observed in clinical trial NCT06520488 [3].
**Pan-RAS Inhibition (RASolute-302)**: The phase III RASolute-302 trial evaluated daraxonrasib (RMC-6236) in second-line metastatic PDAC, reporting a median overall survival of 13.2 months versus 6.6 months for chemotherapy [5].
**Mutation Context**: KRAS G12D is the most common mutation in PDAC (44%), whereas G12C occurs in only 2%-3% [6]. Sotorasib and adagrasib are effective for G12C but not G12D [6].
Caveats
The efficacy data for specific KRAS G12D inhibitors (e.g., MRTX1133, HRS-4642) is largely limited to preclinical models or early-phase clinical observations; no phase III results are published for these agents in PDAC. The RASolute-302 trial supports daraxonrasib, a pan-RAS inhibitor, rather than a G12D-specific agent. Resistance mechanisms are heterogeneous and rapidly emerging, limiting the durability of single-agent KRAS inhibition [2]. Clinical sequencing and combination strategies remain under investigation to overcome these resistance pathways.