1385P - Uncovering resistance mechanisms and vulnerabilities of KEAP1 mutated lung adenocarcinoma

Background

Despite improvements in therapy, lung adenocarcinoma (LUAD) mortality remains high, with fewer than 20% of patients surviving after 5 years. Therefore, overcoming resistance to the already existing therapies and identifying new strategies remains a high priority. Approximately 20% of Kirsten rat sarcoma viral oncogene homolog (KRAS) mutant LUAD carry loss-of-function (LOF) KEAP1 mutations, which confer the worst prognosis of all LUAD subtypes as patients do not respond to standard of care, radiation, immunotherapy, chemotherapy or covalent KRAS^G12C inhibitors.

Methods

Here, we used two (2D) and three-dimensions (3D) in vitro cultures and in vivo pre-clinical models to uncover resistance mechanisms and also vulnerabilities of KEAP1-mutant LUAD.

Results

We found that, although Keap1 loss did not lead to growth differences in 2D cultures, in 3D its loss led to increased spheroids’ size (p<0.001) and higher EdU staining. Importantly, similar patterns were seen with the pharmacological inhibition of Keap1 by KI696 and rescued by the knockout of NRF2. In addition, we observed an increased expression of NRF2 targets, NQO1 (p<0.01) and HO1 (p<0.001), in Keap1-knockout spheroids compared to those cultured in two-dimensions, suggesting a greater requirement of NRF2 pathway in the 3D system. We also explored how Keap1-mutated tumors respond to KRAS inhibitors (Kras^G12Di). Keap1-low/NRF2-high tumors were significantly less sensitive to the newly developed Kras^G12D inhibitor, MRTX1133 (Mirati Therapeutics), measured by both tumor size (p<0.05) and tumor weight at end point (p=0.01). RNAseq of lung spheroids treated with MRTX1133 are being performed to bring to light how the loss of Keap1 is able to support survival upon the treatment with Kras^G12D inhibitors.

Conclusions

Taken together these findings will contribute to the understanding of resistance mechanisms and will give us insights of therapeutic strategies to determine the best-individualized treatments.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Fernando Simabuco and Thales Papagiannakopoulos.

Funding

The São Paulo Research Foundation.

Disclosure

All authors have declared no conflicts of interest.