Research into cancer treatment has been mainly focused on developing therapies to directly target cancer cells. Over the past decade, extensive studies have revealed critical roles of the tumour microenvironment (TME) in cancer initiation, progression, and drug resistance. Notably, cancer-associated fibroblasts (CAFs) have emerged as one of the primary contributors in shaping TME, creating a favourable environment for cancer development. Many preclinical studies have identified promising targets on CAFs, demonstrating remarkable efficacy of some CAF-targeted treatments in preclinical models. Encouraged by these compelling findings, therapeutic strategies have now advanced into clinical evaluation. We aim to provide a comprehensive review of relevant subjects on CAFs, including CAF-related markers and targets, their multifaceted roles, and current landscape of ongoing clinical trials. This knowledge can guide future research on CAFs and advocate for clinical investigations targeting CAFs.

Cancer cachexia is a common condition in many cancer patients, particularly those with advanced disease. Cancer cachexia patients are generally less tolerant to chemotherapies and radiotherapies, largely limiting their treatment options. While the search for treatments of this condition are ongoing, standards for the efficacy of treatments have yet to be developed. Current diagnostic criteria for cancer cachexia are primarily based on loss of body mass and muscle function. However, these criteria are rather limiting, and in time, when weight loss is noticeable, it may be too late for treatment. Consequently, biomarkers for cancer cachexia would be valuable adjuncts to current diagnostic criteria, and for assessing potential treatments. Using high throughput methods such as “omics approaches”, a plethora of potential biomarkers have been identified. This article reviews and summarizes current studies of biomarkers for cancer cachexia.

Selective antibody targeted delivery of α particle emitting actinium-225 to tumors has significant therapeutic potential. This work highlights the design and synthesis of a new bifunctional macrocyclic diazacrown ether chelator, H₂MacropaSqOEt, that can be conjugated to antibodies and forms stable complexes with actinium-225. The macrocyclic diazacrown ether chelator incorporates a linker comprised of a short polyethylene glycol fragment and a squaramide ester that allows selective reaction with lysine residues on antibodies to form stable vinylogous amide linkages. This new H₂MacropaSqOEt chelator was used to modify a monoclonal antibody, girentuximab (hG250), that binds to carbonic anhydrase IX, an enzyme that is overexpressed on the surface of cancers such as clear cell renal cell carcinoma. This new antibody conjugate (H₂MacropaSq-hG250) had an average chelator to antibody ratio of 4 : 1 and retained high affinity for carbonic anhydrase IX. H₂MacropaSq-hG250 was radiolabeled quantitatively with [²²⁵Ac]Ac^III within one minute at room temperature with micromolar concentrations of antibody and the radioactive complex is stable in human serum for >7 days. Evaluation of [²²⁵Ac]Ac(MacropaSq-hG250) in a mouse xenograft model, that overexpresses carbonic anhydrase IX, demonstrated a highly significant therapeutic response. It is likely that H₂MacropaSqOEt could be used to modify other antibodies providing a readily adaptable platform for other actinium-225 based therapeutics.

Background: Developing therapies for cancer cachexia has not been successful to date, in part due to the challenges of achieving robust quantitative measures as a readout of patient treatment. Hence, identifying biomarkers to assess the outcomes of treatments for cancer cachexia is of great interest and important for accelerating future clinical trials. Methods: We established a novel xenograft model for cancer cachexia with a cachectic human PC3* cell line, which was responsive to anti-Fn14 mAb treatment. Using RNA-seq and secretomic analysis, genes differentially expressed in cachectic and non-cachectic tumors were identified and validated by digital droplet PCR (ddPCR). Correlation analysis was performed to investigate their impact on survival in cancer patients. Results: A total of 46 genes were highly expressed in cachectic PC3* tumors, which were downregulated by anti-Fn14 mAb treatment. High expression of the top 10 candidates was correlated with low survival and high cachexia risk in different cancer types. Elevated levels of LCN2 were observed in serum samples from cachectic patients compared with non-cachectic cancer patients. Conclusion: The top 10 candidates identified in this study are candidates as potential biomarkers for cancer cachexia. The diagnostic value of LCN2 in detecting cancer cachexia is confirmed in patient samples.

The Eph receptor tyrosine kinase EphA3 is over-expressed in a range of tumours, most commonly in the tumour microenvironment (TME), including in immunosuppressive cancer-associated fibroblasts (CAFs). In contrast, normal homeostatic tissues show little or no expression of EphA3, making it an attractive therapeutic target. We previously developed a humanized EphA3 antibody (Ifabotuzumab) which was tested in preclinical models and in phase I clinical trials, showing tumour specificity and biological activity. To improve its efficacy, we have tested novel antibody-drug conjugates (ADCs) of Ifabotuzumab with the microtubule disruptor monomethyl auristatin E (MMAE), the Topoisomerase I inhibitor deruxtecan (DXd), and the DNA binding cytotoxin pyrrolobenzodiazepine dimer (PBD), using cleavable linkers and site-specific ‘AJICAP’ peptide-mediated conjugation. In vitro analysis showed retention of specific binding of Ifabotuzumab-ADCs to EphA3 and specific, dose-dependent killing of EphA3-expressing cells. Ifabotuzumab-PBD showed the highest in-vitro potency and was alone effective against EphA3-expressing cancer-associated fibroblasts. Treatment of mice bearing EphA3-expressing tumour xenografts with all Ifabotuzumab-ADCs decreased tumour growth and increased survival, again with Ifabotuzumab-PBD the most efficacious. Ifabotuzumab-PBD was also able to inhibit growth of tumours that express EphA3 only in stromal cells in the TME, using syngeneic tumour models in immunocompetent mice. Notably, combination with the immune-checkpoint inhibitor anti-PD1 increased CD8+ T cells in tumours, and improved tumour inhibition, compared to anti-PD1 alone. This data indicates that Ifabotuzumab-ADCs have potential as novel specific anti-tumour agents capable of targeting the TME in solid tumours.