Abstract Background About 10% of NSCLCs are mutated in KRAS and impaired in STK11/LKB1 , a genetic background associated with poor prognosis, caused by an increase in metastatic burden and resistance to standard therapy. LKB1 is a protein involved in a number of biological processes and is particularly important for its role in the regulation of cell metabolism. LKB1 alterations lead to protein loss that causes mitochondria and metabolic dysfunction that makes cells unable to respond to metabolic stress. Different studies have shown how it is possible to interfere with cancer metabolism using metformin and caloric restriction (CR) and both modify the tumor microenvironment (TME), stimulating the switch from “cold” to “hot”. Given the poor therapeutic response of KRAS mut / LKB1 mut patients, and the role of LKB1 in cell metabolism, we examined whether the addition of metformin and CR enhanced the response to chemo or chemo-immunotherapy in LKB1 impaired tumors. Methods Mouse cell lines were derived from lung nodules of transgenic mice carrying KRAS G12D with either functional LKB1 (KRAS G12D /LKB1 wt ) or mutated LKB1 (KRAS G12D /LKB1 mut ). Once stabilized in vitro, these cell lines were inoculated subcutaneously and intramuscularly into immunocompetent mice. Additionally, a patient-derived xenograft (PDX) model was established by directly implanting tumor fragments from patient into immunocompromised mice. The mice bearing these tumor models were subjected to treatment with chemotherapy or chemo-immunotherapy, both as standalone regimens and in combination with metformin and CR. Results Our preclinical results indicate that in NSCLC KRAS mut / LKB1 mut tumors, metformin and CR do enhance the response to chemo and chemo-immunotherapy, inducing a metabolic stress condition that these tumors are not able to overcome. Analysis of immune infiltrating cells did not bring to light any strong correlation between the TME immune-modulation and the tumor response to metformin and CR. Conclusion Our in vitro and in vivo preliminary studies confirm our hypothesis that the addition of metformin and CR is able to improve the antitumor activity of chemo and chemoimmunotherapy in LKB1 impaired tumors, exploiting their inability to overcome metabolic stress.
Abstract Introduction: Lung cancer is one of the leading cause of cancer death worldwide, with an estimate incidence of about 2 million new cases per year. Among all lung cancers, non-small-cell lung cancer (NSCLC) is the most frequent (nearly 85%) with a 5-year survival of about 25% when all stages are considered.NSCLCs are frequently mutated in KRAS or STK11/LKB1 and co-mutation is often reported. Considering the key role of STK11/LKB1 in controlling cell metabolism, we hypothesized that NSCLC harboring mutations in this gene could be vulnerable to metabolic stresses. Different studies in the last years have highlighted how is possible to interfere with cancer metabolism using metformin and caloric restriction.Our work aimed at investigating the role of metabolic stress in determining response to chemotherapy and immunotherapy in LKB1 mutated NSCLC model. Methods: For isolation of cell lines with the genetic backgrounds, nodules from lungs of KRASG12D/LKB1wt and KRASG12D/LKB1mut transgenic mice were used. Stabilized cell lines were then inoculated intramuscularly in immunocompetent mice and treated with chemotherapy alone (cisplatin) or in combination with metformin and caloric restriction. Caloric restriction consisted of 36 hours of fasting every week for three weeks. Metformin was administered daily for the entire experiment while cisplatin was given once a week for three weeks. Results: We started our in vivo experiments comparing the response of the tumors characterized by the mutation in KRASG12D or the co-mutation KRASG12D/LKB1mut. The results indicate that the addition of metformin and caloric restriction improve the activity of cisplatin in both tumors but a stronger effect was detected in tumors presenting the deletion of LKB1. In fact, only in the latter group, the effect of the combination lasted beyond the end of the treatment slowing down the tumor growth. The different combinations were well tolerated. Molecular analysis on tumor samples run in parallel are in progress. Conclusion: Our in vivo preliminary studies confirm our hypothesis that the addition of the caloric restriction and metformin is able to improve the antitumor activity of the cisplatin without increasing the treatment toxicity in tumors characterized by the co-mutations of KRASG12D/LKB1mut. Further investigations are ongoing on the role of metabolic stress in addition to the immunotherapy (using anti PD-1 antibody as immunocheckpoint inhibitor). Citation Format: Gloriana Ndembe, Mirko Marabese, Ilenia Intini, Alessandra Fabbri, Massimo Moro, Mario Occhipinti, Elisa Sottotetti, Giuseppe Lo Russo, Monica Ganzinelli, Massimo Broggini. The effect of metabolic alterations on chemo-immunotherapy response in non-small-cell lung cancer model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2380.
LKB1 (liver kinase B1) is a master regulator of several processes such as metabolism, proliferation, cell polarity and immunity. About one third of non-small cell lung cancers (NSCLCs) present LKB1 alterations, which almost invariably lead to protein loss, resulting in the absence of a potential druggable target. In addition, LKB1-null tumors are very aggressive and resistant to chemotherapy, targeted therapies and immune checkpoint inhibitors (ICIs). In this review, we report and comment strategies that exploit peculiar co-vulnerabilities to effectively treat this subgroup of NSCLCs. LKB1 loss leads to an enhanced metabolic avidity, and treatments inducing metabolic stress were successful in inhibiting tumor growth in several preclinical models. Biguanides, by compromising mitochondria and reducing systemic glucose availability, and the glutaminase inhibitor telaglenastat (CB-839), inhibiting glutamate production and reducing carbon intermediates essential for TCA cycle progression, have provided the most interesting results and entered different clinical trials enrolling also LKB1-null NSCLC patients. Nutrient deprivation has been investigated as an alternative therapeutic intervention, giving rise to interesting results exploitable to design specific dietetic regimens able to counteract cancer progression. Other strategies aimed at targeting LKB1-null NSCLCs exploit its pivotal role in modulating cell proliferation and cell invasion. Several inhibitors of LKB1 downstream proteins, such as mTOR, MEK, ERK and SRK/FAK, resulted specifically active on LKB1 -mutated preclinical models and, being molecules already in clinical experimentation, could be soon proposed as a specific therapy for these patients. In particular, the rational use in combination of these inhibitors represents a very promising strategy to prevent the activation of collateral pathways and possibly avoid the potential emergence of resistance to these drugs. LKB1-null phenotype has been correlated to ICIs resistance but several studies have already proposed the mechanisms involved and potential interventions. Interestingly, emerging data highlighted that LKB1 alterations represent positive determinants to the new KRAS specific inhibitors response in KRAS co-mutated NSCLCs. In conclusion, the absence of the target did not block the development of treatments able to hit LKB1 -mutated NSCLCs acting on several fronts. This will give patients a concrete chance to finally benefit from an effective therapy.
