Immunotherapy through the Lens of Non-Small Cell Lung Cancer.

Immunotherapy has revolutionised anti-cancer treatment in solid organ malignancies. Specifically, the discovery of CTLA-4 followed by PD-1 in the early 2000s led to the practice-changing clinical development of immune checkpoint inhibitors (ICI). Patients with lung cancer, including both small cell (SCLC) and non-small cell lung cancer (NSCLC), benefit from the most commonly used form of immunotherapy in immune checkpoint inhibitors (ICI), resulting in increased survival and quality of life. In NSCLC, the benefit of ICIs has now extended from advanced NSCLC to earlier stages of disease, resulting in durable benefits and the even the emergence of the word 'cure' in long term responders. However, not all patients respond to immunotherapy, and few patients achieve long-term survival. Patients may also develop immune-related toxicity, a small percentage of which is associated with significant mortality and morbidity. This review article highlights the various types of immunotherapeutic strategies, their modes of action, and the practice-changing clinical trials that have led to the widespread use of immunotherapy, with a focus on ICIs in NSCLC and the current challenges associated with advancing the field of immunotherapy.

Histone Deacetylase 6 Inhibition Exploits Selective Metabolic Vulnerabilities in LKB1 Mutant, KRAS Driven NSCLC.

INTRODUCTION: In KRAS-mutant NSCLC, co-occurring alterations in LKB1 confer a negative prognosis compared with other mutations such as TP53. LKB1 is a tumor suppressor that coordinates several signaling pathways in response to energetic stress. Our recent work on pharmacologic and genetic inhibition of histone deacetylase 6 (HDAC6) revealed the impaired activity of numerous enzymes involved in glycolysis. On the basis of these previous findings, we explored the therapeutic window for HDAC6 inhibition in metabolically-active KRAS-mutant lung tumors. METHODS: Using cell lines derived from mouse autochthonous tumors bearing the KRAS/LKB1 (KL) and KRAS/TP53 mutant genotypes to control for confounding germline and somatic mutations in human models, we characterize the metabolic phenotypes at baseline and in response to HDAC6 inhibition. The impact of HDAC6 inhibition was measured on cancer cell growth in vitro and on tumor growth in vivo. RESULTS: Surprisingly, KL-mutant cells revealed reduced levels of redox-sensitive cofactors at baseline. This is associated with increased sensitivity to pharmacologic HDAC6 inhibition with ACY-1215 and blunted ability to increase compensatory metabolism and buffer oxidative stress. Seeking synergistic metabolic combination treatments, we found enhanced cell killing and antitumor efficacy with glutaminase inhibition in KL lung cancer models in vitro and in vivo. CONCLUSIONS: Exploring the differential metabolism of KL and KRAS/TP53-mutant NSCLC, we identified decreased metabolic reserve in KL-mutant tumors. HDAC6 inhibition exploited a therapeutic window in KL NSCLC on the basis of a diminished ability to compensate for impaired glycolysis, nominating a novel strategy for the treatment of KRAS-mutant NSCLC with co-occurring LKB1 mutations.