The complex liaison between cachexia and tumor burden (Review)

Low-dose orthotopic cancer implantation permits measurement of longitudinal functional changes associated with cachexia

Progressive functional decline is a key element of cancer-associated cachexia. Major barriers to translating preclinical therapies into the clinic include lack of cancer models that accurately mimic functional decline, which develops over time, and use of nonspecific measures, like grip strength, as surrogates for physical function. In this study, we aimed to extend the survival and longevity of a cancer model, to investigate cachexia-related function at the basic science level. Survival extension studies were performed by testing multiple cell lines, dilutions, and vehicle-types in orthotopic implantation of K-rasLSL.G12D/+; Trp53R172H/+; Pdx-1-Cre (KPC)-derived cells. One hundred twenty-eight animals in this new model were assessed for cachexia syndrome phenotype using a battery of anatomical, biochemical, and behavioral techniques. We extended the survival of the KPC orthotopic model to 8-9 wk postimplantation using a relatively low 100-cell dose of DT10022 KPC cells (P < 0.001). In this low-dose orthotopic (LO) model, progressive muscle wasting was detected in parallel to systemic inflammation; skeletal muscle atrophy at the fiber level was detected as early as 3 wk postimplantation compared with controls (P < 0.001). Gait speed in LO animals declined as early as 2 wk postimplantation, whereas grip strength change was a late event. Principal component and regression analyses revealed distinct cachectic and noncachectic animal populations, which we leveraged to show that the gait speed decline was specific to cachexia (P < 0.01), whereas grip strength decline was not (P = 0.19). Gait speed represents an accurate surrogate for cachexia-related physical function as opposed to grip strength.NEW & NOTEWORTHY Previous studies of cancer-induced cachexia have been confounded by the relatively rapid death of animal subjects. Using a lower dose of cancer cells in combination with a battery of behavioral, structural, histological, and biochemical techniques, we show that gait speed is actually the best indicator of functional decline due to cachexia. Future studies are required to define the underlying physiological basis of these findings.

A novel SLC3A2-targeting antibody-drug conjugate exerts potent antitumor efficacy in head and neck squamous cell cancer

The development of innovative therapeutic strategies for head and neck squamous cell carcinoma (HNSCC) is a critical medical requirement. Antibody-drug conjugates (ADC) targeting tumor-specific surface antigens have demonstrated clinical effectiveness in treating hematologic and solid malignancies. Our investigation revealed high expression levels of SLC3A2 in HNSCC tissue and cell lines. This study aimed to develop a novel anti-SLC3A2 ADC and assess its antitumor effects on HNSCC both in vitro and in vivo. This study developed a potent anti-SLC3A2 ADC (19G4-MMAE) and systematically investigated its drug delivery potential and antitumor efficacy in preclinical models. This study revealed that 19G4-MMAE exhibited specific binding to SLC3A2 and effectively targeted lysosomes. Moreover, 19G4-MMAE induced a significant accumulation of reactive oxygen species (ROS) and apoptosis in SLC3A2-positive HNSCC cells. The compound demonstrated potent antitumor effects derived from MMAE against SLC3A2-expressing HNSCC in preclinical models, displaying a favorable safety profile. These findings suggest that targeting SLC3A2 with an anti-SLC3A2 ADC could be a promising therapeutic approach for treating HNSCC patients.

Histopathologic Features of Mucosal Head and Neck Cancer Cachexia

Objective

Determine the histopathologic features that correlate with head and neck cancer (HNC) cachexia.

Methods

A single-institution, retrospective study was performed on adults with HPV-negative, mucosal squamous cell carcinoma of the aerodigestive tract undergoing resection and free flap reconstruction from 2014 to 2019. Patients with distant metastases were excluded. Demographics, comorbidities, preoperative nutrition, and surgical pathology reports were collected. Comparisons of histopathologic features and cachexia severity were made.

Results

The study included 222 predominantly male (64.9%) patients aged 61.3 ± 11.8 years. Cachexia was identified in 57.2% patients, and 18.5% were severe (≥15% weight loss). No differences in demographics were identified between the groups. Compared to control, patients with severe cachexia had lower serum hemoglobin (p=0.048) and albumin (p < 0.001), larger tumor diameter (p < 0.001), greater depth of invasion (p < 0.001), and elevated proportions of pT4 disease (p < 0.001), pN2-N3 disease (p=0.001), lymphovascular invasion (p=0.009), and extranodal extension (p=0.014). Multivariate logistic regression identified tumor size (OR [95% CI] = 1.36 [1.08-1.73]), oral cavity tumor (OR [95% CI] = 0.30 [0.11-0.84]), and nodal burden (OR [95% CI] = 1.16 [0.98-1.38]) as significant histopathologic contributors of cancer cachexia.

Conclusions

Larger, more invasive tumors with nodal metastases and aggressive histologic features are associated with greater cachexia severity in mucosal HNC.

Gait speed is a biomarker of cancer-associated cachexia decline and recovery

Background

Progressive functional decline is a key element of cancer-associated cachexia. No therapies have successfully translated to the clinic due to an inability to measure and improve physical function in cachectic patients. Major barriers to translating pre-clinical therapies to the clinic include lack of cancer models that accurately mimic functional decline and use of non-specific outcome measures of function, like grip strength. New approaches are needed to investigate cachexia-related function at both the basic and clinical science levels.

Methods

Survival extension studies were performed by testing multiple cell lines, dilutions, and vehicle-types in orthotopic implantation of K-ras LSL.G12D/+ ; Trp53 R172H/+ ; Pdx-1-Cre (KPC) derived cells. 128 animals in this new model were then assessed for muscle wasting, inflammation, and functional decline using a battery of biochemical, physiologic, and behavioral techniques. In parallel, we analyzed a 156-subject cohort of cancer patients with a range of cachexia severity, and who required rehabilitation, to determine the relationship between gait speed via six-minute walk test (6MWT), grip strength (hGS), and functional independence measures (FIM). Cachectic patients were identified using the Weight Loss Grading Scale (WLGS), Fearon consensus criteria, and the Prognostic Nutritional Index (PNI).

Results

Using a 100-cell dose of DT10022 KPC cells, we extended the survival of the KPC orthotopic model to 8-9 weeks post-implantation compared to higher doses used (p<0.001). In this Low-dose Orthotopic (LO) model, both progressive skeletal and cardiac muscle wasting were detected in parallel to systemic inflammation; skeletal muscle atrophy at the fiber level was detected as early as 3 weeks post-implantation compared to controls (p<0.001). Gait speed in LO animals declined as early 2 week post-implantation whereas grip strength change was a late event and related to end of life. Principle component analysis (PCA) revealed distinct cachectic and non-cachectic animal populations, which we leveraged to show that gait speed decline was specific to cachexia (p<0.01) while grip strength decline was not (p=0.19). These data paralleled our observations in cancer patients with cachexia who required rehabilitation. In cachectic patients (identified by WLGS, Fearon criteria, or PNI, change in 6MWT correlated with motor FIM score changes while hGS did not (r 2 =0.18, p<0.001). This relationship between 6MWT and FIM in cachectic patients was further confirmed through multivariate regression (r 2 =0.30, p<0.001) controlling for age and cancer burden.

Conclusion

Outcome measures linked to gait are better associated with cachexia related function and preferred for future pre-clinical and clinical cachexia studies.

Progressive development of melanoma-induced cachexia differentially impacts organ systems in mice

Cachexia is a systemic wasting syndrome that increases cancer-associated mortality. How cachexia progressively and differentially impacts distinct tissues is largely unknown. Here, we find that the heart and skeletal muscle undergo wasting at early stages and are the tissues transcriptionally most impacted by cachexia. We also identify general and organ-specific transcriptional changes that indicate functional derangement by cachexia even in tissues that do not undergo wasting, such as the brain. Secreted factors constitute a top category of cancer-regulated genes in host tissues, and these changes include upregulation of the angiotensin-converting enzyme (ACE). ACE inhibition with the drug lisinopril improves muscle force and partially impedes cachexia-induced transcriptional changes, although wasting is not prevented, suggesting that cancer-induced host-secreted factors can regulate tissue function during cachexia. Altogether, by defining prevalent and temporal and tissue-specific responses to cachexia, this resource highlights biomarkers and possible targets for general and tissue-tailored anti-cachexia therapies.

Impact of cancer cachexia on respiratory muscle function and the therapeutic potential of exercise

Cancer cachexia is defined as a multi-factorial syndrome characterised by an ongoing loss of skeletal muscle mass and progressive functional impairment, estimated to affect 50-80% of patients and responsible for 20% of cancer deaths. Elevations in the morbidity and mortality rates of cachectic cancer patients has been linked to respiratory failure due to atrophy and dysfunction of the ventilatory muscles. Despite this, there is a distinct scarcity of research investigating the structural and functional condition of the respiratory musculature in cancer, with the majority of studies exclusively focusing on limb muscle. Treatment strategies are largely ineffective in mitigating the cachectic state. It is now widely accepted that an efficacious intervention will likely combine elements of pharmacology, nutrition and exercise. However, of these approaches, exercise has received comparatively little attention. Therefore, it is unlikely to be implemented optimally, whether in isolation or combination. In consideration of these limitations, the current review describes the mechanistic basis of cancer cachexia and subsequently explores the available respiratory- and exercise-focused literature within this context. The molecular basis of cachexia is thoroughly reviewed. The pivotal role of inflammatory mediators is described. Unravelling the mechanisms of exercise-induced support of muscle via antioxidant and anti-inflammatory effects in addition to promoting efficient energy metabolism via increased mitochondrial biogenesis, mitochondrial function and muscle glucose uptake provide avenues for interventional studies. Currently available pre-clinical mouse models including novel transgenic animals provide a platform for the development of multi-modal therapeutic strategies to protect respiratory muscles in people with cancer.

The myokine Fibcd1 is an endogenous determinant of myofiber size and mitigates cancer-induced myofiber atrophy

Decline in skeletal muscle cell size (myofiber atrophy) is a key feature of cancer-induced wasting (cachexia). In particular, atrophy of the diaphragm, the major muscle responsible for breathing, is an important determinant of cancer-associated mortality. However, therapeutic options are limited. Here, we have used Drosophila transgenic screening to identify muscle-secreted factors (myokines) that act as paracrine regulators of myofiber growth. Subsequent testing in mouse myotubes revealed that mouse Fibcd1 is an evolutionary-conserved myokine that preserves myofiber size via ERK signaling. Local administration of recombinant Fibcd1 (rFibcd1) ameliorates cachexia-induced myofiber atrophy in the diaphragm of mice bearing patient-derived melanoma xenografts and LLC carcinomas. Moreover, rFibcd1 impedes cachexia-associated transcriptional changes in the diaphragm. Fibcd1-induced signaling appears to be muscle selective because rFibcd1 increases ERK activity in myotubes but not in several cancer cell lines tested. We propose that rFibcd1 may help reinstate myofiber size in the diaphragm of patients with cancer cachexia.

Computed tomography with segmentation and quantification of individual organs in a D. melanogaster tumor model

Drosophila melanogaster tumor models are growing in popularity, driven by the high degree of genetic as well as functional conservation to humans. The most common method to measure the effects of a tumor on distant organs of a human cancer patient is to use computed tomography (CT), often used in diagnosing cachexia, a debilitating cancer-induced syndrome most visibly characterized by loss of muscle mass. Successful application of high resolution micro-CT scanning of D. melanogaster was recently reported and we here present the segmentation of all visible larval organs at several stages of tumor development. We previously showed the strong expected reduction in muscle mass as the tumor develops, and we here report a surprisingly strong reduction also in gut and Malpighian tubules (kidney) volume. Time-point of tumor development was found to have a stronger correlation to cachectic organ volume loss than tumor volume, giving support to the previously proposed idea that tumor size does not directly determine degree of cachexia.

Anticachectic regulator analysis reveals Perp-dependent antitumorigenic properties of 3-methyladenine in pancreatic cancer

Approximately 80% of pancreatic cancer patients suffer from cachexia, and one-third die due to cachexia-related complications such as respiratory failure and cardiac arrest. Although there has been considerable research into cachexia mechanisms and interventions, there are, to date, no FDA-approved therapies. A major contributing factor for the lack of therapy options could be the failure of animal models to accurately recapitulate the human condition. In this study, we generated an aged model of pancreatic cancer cachexia to compare cachexia progression in young versus aged tumor-bearing mice. Comparative skeletal muscle transcriptome analyses identified 3-methyladenine (3-MA) as a candidate antiwasting compound. In vitro analyses confirmed antiwasting capacity, while in vivo analysis revealed potent antitumor effects. Transcriptome analyses of 3-MA-treated tumor cells implicated Perp as a 3-MA target gene. We subsequently (a) observed significantly higher expression of Perp in cancer cell lines compared with control cells, (b) noted a survival disadvantage associated with elevated Perp, and (c) found that 3-MA-associated Perp reduction inhibited tumor cell growth. Finally, we have provided in vivo evidence that survival benefits conferred by 3-MA administration are independent of its effect on tumor progression. Taken together, we report a mechanism linking 3-MA to Perp inhibition, and we further implicate Perp as a tumor-promoting factor in pancreatic cancer.

Integrative evaluation of primary and metastatic lesion spectrum to guide anti-PD-L1 therapy of non-small cell lung cancer: results from two randomized studies

Objectives: Clinical benefits of immune-checkpoint blockade (ICB) versus standard chemotherapy have been established in unselected non-small cell lung cancer (NSCLC). However, the response to ICB therapy among patients is heterogeneous in clinical practice. Materials and Methods: We retrospectively assessed the predicitive effect of the primary and metastatic lesion spectrum (baseline sum of the longest diameters [SLD], number of metastatic sites and specific organ metastases) on the efficacy of atezolizumab over docetaxel in OAK and POPLAR trial cohorts. A decision model, termed DSO (Diameter-Site-Organ), based on the spectrum was developed and validated for guiding ICB. Results: Higher SLD (>38 mm) and more metastatic sites (≥2) were characterized with pronounced overall survival (OS) benefits from atezolizumab versus docetaxel. Specifically, adrenal gland and brain metastases were identified as favorable predictors of atezolizumab treatment. The DSO model was developed in the discovery cohort to integrate the directive effect of the primary and metastatic lesion spectrum. Remarkably, a general pattern of enhanced efficacy of atezolizumab versus docetaxel was observed along with the increase of the DSO score. For patients with DSO score > 0, atezolizumab yielded a significantly prolonged OS than docetaxel, whereas OS was generally similar between two treatments in patients with DSO score ≤ 0. Equivalent findings were also seen in the internal and external validation cohorts. Conclusions: The response to anti-PD-L1 therapy among patients varied with the primary and metastatic lesion spectrum. The DSO-based system might provide promising medication guidance for ICB treatment in NSCLC patients.

Withaferin A and Ovarian Cancer Antagonistically Regulate Skeletal Muscle Mass

Cachexia is a complex wasting syndrome that overwhelmingly affects the majority of late-stage cancer patients. Additionally, there are currently no efficacious therapeutic agents to treat the muscle atrophy induced by the cancer. While several preclinical studies have investigated the molecular signals orchestrating cachexia, very little information exists pertaining to ovarian cancer and the associated cachexia. Work from our lab has recently demonstrated that the steroidal lactone Withaferin A (WFA) is capable of attenuating the atrophying effects of ovarian cancer in a preclinical mouse model. However, it remained to be determined whether WFA's effect was in response to its anti-tumorigenic properties, or if it was capable of targeting skeletal muscle directly. The purpose of this study was to uncover whether WFA was capable of regulating muscle mass under tumor-free and tumor-bearing conditions. Treatment with WFA led to an improvement in functional muscle strength and mass under tumor-bearing and naïve conditions. WFA and ovarian cancer were observed to act antagonistically upon critical skeletal muscle regulatory systems, notably myogenic progenitors and proteolytic degradation pathways. Our results demonstrated for the first time that, while WFA has anti-tumorigenic properties, it also exerts hypertrophying effects on skeletal muscle mass, suggesting that it could be an anti-cachectic agent in the settings of ovarian cancer.

Reduced lung cancer burden by selective immunomodulators elicits improvements in muscle proteolysis and strength in cachectic mice

Identification of to what extent tumor burden influences muscle mass independently of specific treatments for cancer-cachexia remains to be elucidated. We hypothesized that reduced tumor burden by selective treatment of tumor with immunomodulators may exert beneficial effects on muscle wasting and function in mice. Body and muscle weight, grip strength, physical activity, muscle morphometry, apoptotic nuclei, troponin-I systemic levels, interleukin-6, proteolytic markers, and tyrosine release, and apoptosis markers were determined in diaphragm and gastrocnemius muscles of lung cancer (LP07 adenocarcinoma cells) mice (BALB/c) treated with monoclonal antibodies (mAbs), against immune check-points and pathways (CD-137, cytotoxic T-lymphocyte associated protein-4, programed cell death-1, and CD-19; N = 10/group). Nontreated lung cancer cachectic mice were the controls. T and B cell numbers and macrophages were counted in tumors of both mouse groups. Compared to nontreated cachectic mice, in the mAbs-treated animals, T cells increased, no differences in B cells or macrophages, the variables final body weight, body weight and grip strength gains significantly improved. In diaphragm and gastrocnemius of mAbs-treated cachectic mice, number of apoptotic nuclei, tyrosine release, proteolysis, and apoptosis markers significantly decreased compared to nontreated cachectic mice. Systemic levels of troponin-I significantly decreased in treated cachectic mice compared to nontreated animals. We conclude that reduced tumor burden as a result of selective treatment of the lung cancer cells with immunomodulators elicits per se beneficial effects on muscle mass loss through attenuation of several biological mechanisms that lead to increased protein breakdown and apoptosis, which translated into significant improvements in limb muscle strength but not in physical activity parameters.

Metabolism within the tumor microenvironment and its implication on cancer progression: An ongoing therapeutic target

Since reprogramming energy metabolism is considered a new hallmark of cancer, tumor metabolism is again in the spotlight of cancer research. Many studies have been carried out and many possible therapies have been developed in the last years. However, tumor cells are not alone. A series of extracellular components and stromal cells, such as endothelial cells, cancer-associated fibroblasts, tumor-associated macrophages, and tumor-infiltrating T cells, surround tumor cells in the so-called tumor microenvironment (TME). Metabolic features of these cells are being studied in deep in order to find relationships between metabolism within the TME and tumor progression. Moreover, it cannot be forgotten that tumor growth is able to modulate host metabolism and homeostasis, so that TME is not the whole story. Importantly, the metabolic switch in cancer is just a consequence of the flexibility and adaptability of metabolism and should not be surprising. Treatments of cancer patients with combined therapies including antitumor agents with those targeting stromal cell metabolism, antiangiogenic drugs, and/or immunotherapy are being developed as promising therapeutics.

Local and Systemic Cytokine Profiling for Pancreatic Ductal Adenocarcinoma to Study Cancer Cachexia in an Era of Precision Medicine

Cancer cachexia is a debilitating condition seen frequently in patients with pancreatic ductal adenocarcinoma (PDAC). The underlying mechanisms driving cancer cachexia are not fully understood but are related, at least in part, to the immune response to the tumor both locally and systemically. We hypothesize that there are unique differences in cytokine levels in the tumor microenvironment and systemic circulation between PDAC tumors and that these varying profiles affect the degree of cancer cachexia observed. Patient demographics, operative factors, oncologic factors, and perioperative data were collected for the two patients in the patient derived xenograft (PDX) model. Human pancreatic cancer PDX were created by implanting fresh surgical pancreatic cancer tissues directly into immunodeficient mice. At PDX end point, mouse tumor, spleen and muscle tissues were collected and weighed, muscle atrophy related gene expression measured, and tumor and splenic soluble proteins were analyzed. PDX models were created from surgically resected patients who presented with different degrees of cachexia. Tumor free body weight and triceps surae weight differed significantly between the PDX models and control (P < 0.05). Both PDX groups had increased atrophy related gene expression in muscle compared to control (FoxO1, Socs3, STAT3, Acvr2b, Atrogin-1, MuRF1; P < 0.05). Significant differences were noted in splenic soluble protein concentrations in 14 of 15 detected proteins in tumor bearing mice when compared to controls. Eight splenic soluble proteins were significantly different between PDX groups (P < 0.05). Tumor soluble proteins were significantly different between the two PDX groups in 15 of 24 detected proteins (P < 0.05). PDX models preserve the cachectic heterogeneity found in patients and are associated with unique cytokine profiles in both the spleen and tumor between different PDX. These data support the use of PDX as a strategy to study soluble cachexia protein markers and also further efforts to elucidate which cytokines are most related to cachexia in order to provide potential targets for immunotherapy.

Cachexia, and not obesity, prior to pancreatic cancer diagnosis worsens survival and is negated by chemotherapy

Background

Although advanced pancreatic ductal adenocarcinoma (PDAC) is characterized by progressive weight loss and nutritional deterioration, the effect of cancer cachexia and body mass index (BMI) at diagnosis on survival remains unclear.

Methods

We retrospectively evaluated a prospectively collected internal cancer registry of PDAC cases from 2006-2014 at the Kaiser Permanente Medical Center. Cancer cachexia was defined as weight loss greater than 5% over the 6 months prior to diagnosis. Multivariate cox proportional hazards regression was used to assess the influence of cachexia on survival. To evaluate effect measure modification of this relationship, we performed additional analyses stratified by race, BMI class, stage, receipt of surgery and receipt of chemotherapy. We tested for heterogeneity by fitting models with an interaction term for cachexia and the modifying variable.

Results

Of the 977 patients, 611 (63%) were identified with cachexia. Cachexia in PDAC patients was prevalent across all stages of disease and BMI classes. Patients with cachexia had lower survival (median 4.3 months, IQR 1.7-10.0) compared to those without cachexia (median 5.2 months, IQR 2.0-10.6), log-rank P=0.03. In this analysis BMI at diagnosis was not associated with survival. In the multivariate Cox regression, cachexia was independently associated with decreased overall survival (HR 1.24, CI: 1.06-1.45, P=0.01). However, the effect of cachexia on survival outcomes was modified by receipt of chemotherapy. Cachectic patients who did not receive chemotherapy had a 40% increase in risk of death compared to non-cachectic patients (HR 1.40, CI: 1.12-1.75), while those receiving chemotherapy were unaffected by cachexia (HR 1.04, CI: 0.82-1.32, P_interaction=0.01).

Conclusions

In the largest cohort of pancreatic cancer patients examined to date, cachexia and not obesity is independently associated with worse survival in PDA and its effect is negated by systemic chemotherapy.

An analysis of the types of recently published research in the field of cachexia

Introduction Cachexia is a common complication of many and varied chronic disease processes, yet it has received very little attention as an area of clinical research effort until recently. We sought to survey the contemporary literature on published research into cachexia to define where it is being published and the proportion of output classified into the main types of research output. Methods I searched the PubMed listings under the topic research term "cachexia" and related terms for articles published in the calendar years of 2015 and 2016, regardless of language. Searches were conducted and relevant papers extracted by two observers, and disagreements were resolved by consensus. Results There were 954 publications, 370 of which were review articles or commentaries, 254 clinical observations or non-randomised trials, 246 original basic science reports and only 26 were randomised controlled trials. These articles were published in 478 separate journals but with 36% of them being published in a core set of 23 journals. The H-index of these papers was 25 and there were 147 papers with 10 or more citations. Of the top 100 cited papers, 25% were published in five journals. Of the top cited papers, 48% were review articles, 18% were original basic science, and 7% were randomised clinical trials. Discussion This analysis shows a steady but modest increase in publications concerning cachexia with a strong pipeline of basic science research but still a relative lack of randomised clinical trials, with none exceeding 1000 patients. Research in cachexia is still in its infancy, but the solid basic science effort offers hope that translation into randomised controlled clinical trials may eventually lead to effective therapies for this troubling and complex clinical disease process.