von Karstedt, Silvia - A 05

PDAC is amongst the deadliest cancer entities and it is expected to become the second leading cause of cancer-related deaths within this decade^1–3. This poor prognosis is caused by absence of specific early symptoms and primary resistance to chemotherapy highlighting an urgent need to improve our understanding of PDAC tumour biology. One of the key features of PDAC is the high incidence (90%) of activating mutations in the proto-oncogene and small GTPase KRAS. Activating point mutations in KRAS result in attenuation of the intrinsic GTPase activity of KRAS thereby locking it in a constitutively activated state promoting many cancerous traits including cell death resistance, proliferation and migration^4–6. Clinically, KRAS^G12C, ^G12D and ^G12V activating point mutations are found most frequently, with KRAS^G12D being most prevalent in PDAC. 

We have previously shown that oncogenic KRAS is known to promote resistance against apoptosis⁴ and ferroptosis^7,8 but seems explicitly sensitive to necroptosis due to a state we termed “necroptotic priming”⁹. Apart from this potential vulnerability, recent years have seen the clinical development of KRAS^G12C and KRAS^G12D inhibitors^10–12. While these studies are promising, they also revealed that acquired resistance to KRAS^G12C inhibition was largely driven by other mutant forms of KRAS previously undetected¹³. Here, we propose using a genetically engineered mouse model with stochastic expression of KRAS^G12D,^G12V or ^G12C we developed to i) model acquired resistance to KRAS^G12D-targeted therapy with the possibility of outgrowth of other KRAS mutant variants and ii) understand mechanistic underpinnings of this process. Through fulfilment of this program, we anticipate identification of trajectories of KRAS^G12D targeted therapy escape in PDAC and thereby novel strategies for treatment.

While PDAC is projected to become the second leading cause of cancer-related deaths within this decade, patient outlook has not improved since the 1970ies. Thereby, PDAC is still amongst the few cancers with an almost identical rate of incidence and mortality. This marks PDAC as one of the cancers with unmet needs warranting the urgent requirement for novel therapeutic strategies. Here, we propose to leverage state-of the-art clinically tested KRAS^G12D-targeted therapy in a novel mouse model to determine routes of therapy escape via alternative KRAS mutations. Therapeutic approaches identified will be combined with immunotherapy.

• In vivo dynamics of KRAS clonal competition under targeted therapy: 
  Treatment of Oncoprism;Pdx1-Cre and tamoxifen-inducible Pdx1-CreER mice with the KRASG12D inhibitor RMC9895 to monitor tumour response, KRASG12D/G12V/G12C clonal shifts, and relapse. Compare transcriptomes of KRAS clones before and after KRASG12D inhibition after sorting.
   
• Temporal control and relapse assessment:
  Induce KRAS expression at defined stages using tamoxifen-inducible Pdx1-CreER, monitor tumour development over time, and assess immediate response versus delayed regrowth after KRASG12D inhibition to identify which alternative KRAS mutants expand during acquired resistance.
   
• In vitro mechanistic studies: 
  Generate pancreatic organoids for in vitro evaluation of selective/pan-KRAS inhibitors and cell-death vulnerabilities (necroptosis, ferroptosis) in treatment-naïve and resistant settings.

For more information, please check the von Karstedt Lab.

• Center for Molecular Medicine Cologne (CMMC)
• Department of translational Genomics - von Karstedt Lab
• Department of Translational Genomics
• CECAD Cologne
• CECAD lab webpage
• CRC 1310: Predictability in Evolution: How cell death shapes tumor evolution during carcinogenesis
• CRC 1399: Mechanisms of Drug Sensitivity and Resistance in Small Cell Lung Cancer: Immu-editing via programmed cell death in SCLC
• CRC 1403: Cell Death in Immunity, Inflammation and Disease: Inflammatory signalling in ferroptotic cell death
• CRC 1530: Elucidation and targeting of pathogenic mechanisms in B cell malignancies
• SPP 2306: Ferroptosis: from Molecular Basics to Clinical Applications
• BMBF funded collaborative center InCa