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Background: The obesity epidemic is rapidly increasing in the USA and obese women are at a higher likelihood of developing triple negative breast cancer (TNBC). Several studies implicated the importance of the breast microenvironment on the aggressive cancer biology especially obese microenvironment. However, the underlying mechanism(s) by which obesity contributes to the progression of TNBC remains unclear. The objective of this study is to test a novel concept that obesity upregulates leukemia inhibitory factor receptor (LIFR) oncogenic signaling in TNBC and test whether LIFR inhibition blocks TNBC progression. Methods: Established TNBC cell lines were co-cultured with human primary adipocytes or incubated with adipocyte conditioned medium or with high glucose (HG) followed by treatment with LIFR inhibitor EC359. The effect of adiposity on TNBC cells was determined using cell viability, colony formation, and invasion assays. Mechanistic studies were performed using CRISPR/Cas9 KO of LIFR, Western blotting, RT-qPCR, and reporter gene assays. Utility of LIFR inhibitor EC359 was tested using xenografts, and patient derived organoid (PDO) models. Results: Treatment of TNBC cells with adipose conditions or HG increased the proliferation and invasion of TNBC cells. Western blot and RT-qPCR analyses confirmed that increased expression of LIFR correlated with enhanced downstream LIFR signaling such as STAT3 and subsequent activation of STAT3 target genes. CRISPR KO of LIFR or treatment of TNBC cells with EC359 significantly reduced the cell viability, colony formation and invasion under adipose conditions. Western blotting results showed that co-culture with adipocytes significantly enhanced LIFR downstream signaling in TNBC model cells and is effectively blocked by LIFR KO or EC359 treatment. Further, EC359 treatment blocked the adipose environment mediated growth of organoids. Importantly, co-implantation of adipocytes significantly enhanced TNBC xenograft tumor growth, however treatment with EC359 significantly attenuated adipocyte induced TNBC progression. Conclusions: Collectively, these results suggest that adiposity contributes to increased TNBC cell growth via upregulation of the LIF/LIFR pathway. The LIF/LIFR axis represents a potential therapeutic target for adiposity driven TNBC and the LIFR inhibitor EC359 could be used as a new therapeutic agent to treat obesity associated TNBC. Citation Format: Suryavathi Viswanadhapalli, Uday P Pratap, Behnam Ebrahimi, Logan Blankenship, Jaitri Joshi, Zexuan Liu, Kristin A Altwegg, Xiaonan Li, Gangadhara R Sareddy, Bindu Santhamma, Swapna Konda, Manjeet Rao, Edward Kost, Rajeshwar R Tekmal, Hareesh B Nair, Ratna K Vadlamudi. Leukemia inhibitory factor receptor inhibition reduces obesity driven progression of triple negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-10-01.

Methotrexate/6-mercaptopurine maintenance therapy improves acute lymphoblastic leukemia (ALL) outcome. Cytotoxicity is mediated by DNA incorporation of thioguanine nucleotides (DNA-TG). We investigated the association of DNA-TG to relapse risk in 1 910 children and young adults with non-high risk ALL. In a cohort-stratified Cox regression analysis adjusted for sex, age, and white cell count at diagnosis, the relapse-specific hazard ratio (HRa) per 100 fmol/μg increase in weighted mean DNA-TG (wmDNA-TG) was 0.87 (95% CI 0.78-0.97; p = 0.013) in the 839 patients who were minimal residual disease (MRD) positive at end of induction therapy (EOI), whereas this was not the case in EOI MRD-negative patients (p = 0.76). Validation analysis excluding the previously published Nordic NOPHO ALL2008 pediatric cohort yielded a HRa of 0.92 (95% CI 0.82-1.03; p = 0.15) per 100 fmol/μg increase in wmDNA-TG in EOI MRD-positive patients. If also excluding the United Kingdom cohort, in which samples were taken non-randomly in selected patients, the HRa for the EOI MRD-positive patients was 0.82 (95% CI 0.68-0.99; p = 0.044) per 100 fmol/μg increase in wmDNA-TG. The importance of DNA-TG as a biomarker for maintenance therapy intensity calls for novel strategies to increase DNA-TG, although its clinical value may vary by protocol backbone.