Cachexia, cytokines, and caution: lessons from tocilizumab in advanced pancreatic ductal adenocarcinoma

Introduction

Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease, and although chemotherapeutic combinations have modestly improved survival (median ~11 months), most patients still succumb to their disease (1). Cachexia adds greatly to the burden of disease for the vast majority of patients with PDAC (2) and has been found to lead to worse outcomes (3). Cachexia is an underexplored aspect of PDAC management.

This randomized open-label phase II trial (ClinicalTrials.gov identifier: NCT02767557) aimed to compare the efficacy of gemcitabine (Gem)/nab-paclitaxel (Nab) with or without the anti-interleukin-6 (IL-6) receptor antibody tocilizumab (Toc) for advanced PDAC (4). The study was conducted in Denmark and Norway. A total of 147 patients with treatment naïve PDAC were treated with Gem 1,000 mg/m² and Nab 125 mg/m² on days 1, 8, and 15, and Toc 8 mg/kg on day 1 for each 28-day cycle. The primary endpoint was the overall survival (OS) rate at 6 months (OS6). Secondary endpoints were progression-free survival (PFS), overall response rate (ORR), and safety. Exploratory endpoints were cachexia, quality of life, and assessing the cachexia-promoting protein, growth differentiation factor 15 (GDF15), as a biomarker.

The study did not meet its primary endpoint of OS6. OS6 was 68.6% for the Gem/Nab/Toc group and 62.0% for the Gem/Nab group (P=0.409). No differences in median OS, PFS, or ORR were observed. There was a significant trend towards improved survival in the treatment group at 18 months (27.1% vs. 7%). There was a greater number of grade 3 or higher treatment-related adverse events (TrAEs) in the experimental group (88.1% for Gem/Nab/Toc and 63.4% for Gem/Nab). Two treatment-related deaths occurred in the Gem/Nab/Toc group, and one death due to septic shock occurred in the Gem/Nab group. The most common grade 3–4 TrAEs were neutropenia (55.3%), thrombocytopenia (40.8%), infection (19.7%), elevated alanine aminotransferase (18.4%), and diarrhea (17.1%) in the Gem/Nab/Toc group, and infection (21.1%), fatigue (18.3%), and neutropenia (16.9%) in the Gem/Nab group.

The addition of Toc did, however, modestly decrease both the incidence and severity of muscle wasting, signaling a possible anti-cachexia effect of neutralizing IL-6 signaling. Incidence of muscle loss was 43.48% on Gem/Nab/Toc vs. 73.52% on Gem/Nab at 2 months and 41.82% vs. 68.75% at 4 months. Gem/Nab/Toc significantly decreased muscle loss vs. Gem/Nab, with median change +0.101% vs. −3.43% at 2 months and +0.704% vs. −3.35% at 4 months. This finding was independent of GDF15. Global health status worsened in fewer patients in the Gem/Nab/Toc group at week 24 (39% vs. 46%).

Strengths and limitations

This study has several key strengths. The topic of cachexia in PDAC is an important area to be addressed. The Toc arm showed significant preservation of muscle mass, suggestive of a clinically meaningful benefit in addressing cancer-associated muscle wasting. Global health status was improved for patients with this approach. It is unclear how this effect correlates with other clinically meaningful outcomes, however, such as treatment tolerance or patient-reported quality of life. These findings do open the door for future clinical trials investigating the role of Toc in tackling cachexia, a long-neglected aspect of cancer burden, to determine if this novel approach may translate into improved outcomes for patients with PDAC.

This was a well-designed, prospective, multi-center trial that randomized patients prior to treatment initiation. This randomization approach reduced potential selection bias. It is notable that OS6 was chosen as the primary endpoint for this study. While OS is considered the gold standard for assessing treatment effectiveness in oncology clinical trials, it often requires a long follow-up period. OS6, as a shorter-term measure of survival, can serve as a surrogate endpoint to assess the impact of new therapies, especially in aggressive diseases like PDAC, where patients have short survival times. Patients in a first-line trial may, however, receive additional treatments after their initial therapy. This can affect the OS and make it difficult to attribute the observed survival benefit to the studied intervention, particularly within a short timeframe like 6 months.

The OS of 8 months for the Gem/Nab control group was modestly lower than what has traditionally been seen in trials in this setting, such as the MPACT clinical trial, where the median OS was 8.7 months for patients receiving Gem/Nab (5). In MPACT, 12-month OS was 35% vs. 28.2% in the current study. The eligibility criteria for this clinical trial included adequate representation of clinicopathologic features seen in patients with PDAC, including known poor prognostic features such as higher Karnofsky performance status, age <65 years, and presence of liver metastases (6), with representation comparable to the MPACT study. Given the randomized nature of the study, the efficacy results of the control arm were in line with what we observe in a real-world setting (7). It was interesting to note that while the study did not meet its primary endpoint (6-month OS), the study reported 18-month OS rates of 27.1% vs. 7.0% (P=0.001), favoring the Toc arm. Although this finding suggests a potential long-term benefit signal for a subset of patients, this is a post-hoc observation, derived from a small sample and unadjusted for multiplicity.

It was reassuring that the number of grade 3–4 infections was similar between arms, as this is a known side effect of Toc and is an obvious concern for those receiving chemotherapy (19.7% in the Gem/Nab/Toc group and 21.1% in the Gem/Nab group). However, the difference in grade 3 or higher TrAEs between the experimental and control arms was not unsignificant (88.1% for Gem/Nab/Toc and 63.4% for Gem/Nab). This significant difference in rates of high-grade toxicity experienced by patients ultimately weighs against choosing this treatment regimen for unselected patients with PDAC. The significance of high-grade toxicity for patients weighs heavier than modest metabolic improvements of undetermined clinical significance, including lack of a significant survival advantage.

Clinical implications and future directions

This study highlights the role of IL-6 receptor blockade in reducing cancer cachexia, but did not meet its primary endpoint of 6-month OS. There was a significantly higher rate of toxicity in the experimental arm. This study did show possible signals of improving long-term survival for a subset of patients at 18 months. It can be questioned whether the significant trend in survival gain at 18 months was due to random variation vs. the anti-inflammatory effects of Toc itself vs. the reduction in cachexia experienced by patients due to Toc, and further research is needed to determine this. Future research may also assess if Toc can be effectively used to target cachexia in PDAC in earlier stages of the disease to improve surgical and long-term outcomes. Alternatively, it is considering refined dosing to balance safety and efficacy to lessen the rate of high-grade toxicity. For now, the clinical applications of Toc in PDAC remain unclear.

OS6 as a surrogate endpoint has increasingly been used in clinical trials and is most helpful in trials where survival is limited, such as in PDAC, and should be considered for use in future PDAC trials, especially in later lines of therapy.

To advance the development of IL-6 pathway inhibitors like Toc in pancreatic cancer—particularly in the context of systemic inflammation and cachexia—it is essential that future clinical trials incorporate specific biomarkers and translational endpoints. These will help stratify patients, monitor target engagement, and better understand the mechanistic underpinnings of therapeutic response and resistance. A primary focus should be on evaluating baseline levels of IL-6, both in its free and soluble receptor-bound forms, to identify patients with high IL-6 activity who may benefit most from IL-6 blockade. In parallel, commonly available systemic inflammatory markers such as C-reactive protein, serum albumin, and the modified Glasgow Prognostic Score can serve as indicators of systemic inflammation over the course of therapy. However, these should be complemented by more pathway-specific biomarkers—such as phosphorylation of signal transducer and activator of transcription 3 (STAT3) in tumor tissue. This would confirm that IL-6 signaling is being effectively suppressed at the tissue level, particularly within the tumor microenvironment. To determine whether structural preservation of muscle mass translates into meaningful benefit, trials should incorporate physical performance measures such as grip strength, gait speed, the timed up-and-go test, and the 6-minute walk test. These metrics are more clinically meaningful than muscle mass measurements alone. A more mechanistic understanding of cachexia will require tracking circulating levels of known mediators, including GDF15. Although GDF15 was not altered in the current trial, measuring it and other mediators will help delineate which pathways are affected by IL-6 inhibition and which remain active. Lastly, trials should include validated patient-reported outcome measures that assess fatigue, appetite, physical functioning, and symptom burden. Since cachexia has a profound impact on patients’ quality of life, these endpoints may reflect therapeutic benefit even in the absence of radiographic tumor shrinkage.

Conclusions

This is a well-designed, hypothesis-generating study highlighting the potential role of IL-6 receptor blockade in preventing cancer cachexia and possibly signaling improving long-term survival for a subset of patients. However, it did not meet its primary endpoint of OS6, brought additional toxicity, and lacked improvements in response rate or PFS. Metabolic improvements must be weighed against toxicity, particularly without a significant survival advantage. Future studies can leverage these signal-generating findings to determine the role of Toc as an anti-cachexia precision tool, identify predictive biomarkers to select patients most likely to derive durable benefit, explore earlier integration of Toc or refined dosing to balance efficacy and safety as well as confirm long-term survival trends in a larger, controlled setting.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, AME Clinical Trials Review. The article has undergone external peer review.

Peer Review File: Available at https://actr.amegroups.com/article/view/10.21037/actr-25-92/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://actr.amegroups.com/article/view/10.21037/actr-25-92/coif). The authors have no conflicts of interest to declare.

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