Incidence, risk factors and clinical outcome of venous thromboembolism in non-small cell lung cancer patients receiving immune checkpoint inhibition

Lung Cancer Related Thrombosis (LCART): Focus on Immune Checkpoint Blockade

Cancer-associated thrombosis (CAT) is a common complication in lung cancer patients. Lung cancer confers an increased risk of thrombosis compared to other solid malignancies across all stages of the disease. Newer treatment agents, including checkpoint immunotherapy and targeted agents, may further increase the risk of CAT. Different risk-assessment models, such as the Khorana Risk Score, and newer approaches that incorporate genetic risk factors have been used in lung cancer patients to evaluate the risk of thrombosis. The management of CAT is based on the results of large prospective trials, which show similar benefits to low-molecular-weight heparins (LMWHs) and direct oral anticoagulants (DOACs) in ambulatory patients. The anticoagulation agent and duration of therapy should be personalized according to lung cancer stage and histology, the presence of driver mutations and use of antineoplastic therapy, including recent curative lung surgery, chemotherapy or immunotherapy. Treatment options should be evaluated in the context of the COVID-19 pandemic, which has been shown to impact the thrombotic risk in cancer patients. This review focuses on the epidemiology, pathophysiology, risk factors, novel predictive scores and management of CAT in patients with active lung cancer, with a focus on immune checkpoint inhibitors.

Venous thromboembolism incidence and risk factors associated with immune checkpoint inhibitors among patients with advanced non-small cell lung cancer

BACKGROUND

Venous thromboembolism (VTE) is a significant cause of morbidity and mortality in patients with lung cancer. Systemic therapies, such as chemotherapy (chemo), are associated with increased risk of VTE. Immune checkpoint inhibitors (ICIs) are a new standard of care for the treatment of lung cancer, but their association with VTE is not fully understood. We evaluated the incidence of VTE and risk factors for patients with advanced non-small cell lung cancer (aNSCLC) treated with first-line ICI-based, chemo-based, or ICI+chemo regimens.

METHODS

This retrospective cohort study used HealthCore Integrated Research Environment - Oncology data, an integrated database of administrative claims, coupled with clinical data from a cancer-care quality program. Patients with first-line treatment of stage IV non-small cell lung cancer from July 2014 to August 2020 were grouped based on three treatment types: ICI-based, chemo-based, or ICI+chemo. Patients with VTE before initiation of systemic treatment were excluded. Newly diagnosed VTE events were identified via inpatient and outpatient diagnosis codes. Cox proportional hazards models were used to investigate the factors associated with VTE risk.

RESULTS

Among 2299 eligible patients (ICI-based, n=605; chemo-based, n=1092; ICI+chemo, n=602) with a median follow-up of 9.1 months, the VTE incidence rates (95% CI) per 100 person-years were 17.8 (95% CI 16.0 to 19.5) overall, 13.5 (95% CI 10.6 to 16.5) for ICI-based, 18.0 (95% CI 15.5 to 20.5) for chemo-based, and 22.4 (95% CI 20.2 to 24.5) for ICI+chemo. The 6-month cumulative incidence of VTE was 8.1% for ICI-based, 10.9% for chemo-based, and 12.8% for ICI+chemo. Pulmonary embolism was most common, accounting for 63% of the VTE events. After controlling for baseline patient characteristics, the risk of VTE was 26% lower for ICI-based regimens than for chemo-based regimens (HR 0.74, p=0.03). There was no meaningful difference in the risk between ICI+chemo and chemo-based regimens (HR 1.12, p=0.36). Previous radiation and severe obesity (body mass index ≥40) were associated with VTE.

CONCLUSIONS

VTE incidence rate per 100 person-years was common across regimens in patients with aNSCLC, but numerically lower for patients receiving ICI-based regimens compared with those receiving chemo-based and ICI+chemo regimens. VTE is a common complication of lung cancer, and there is a continued need for awareness of VTE as a comorbidity in this population.

Risk of Thromboembolic Events in Cancer Patients Treated with Immune Checkpoint Inhibitors: A Meta-analysis of Randomized Controlled Trials

BACKGROUND

 The association between immune checkpoint inhibitors (ICIs) and thromboembolic events (TEEs) remains controversial.

OBJECTIVE

 The goal of this study was to assess the risk of major TEEs associated with ICIs.

METHODS

 We explored ICI-related TEEs in randomized controlled trials available in ClinicalTrials.gov and electronic databases up to June 30, 2021. Meta-analysis was performed by using Peto odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

 A total of 61 studies were included. Patients treated with ICIs had a similar risk of venous thromboembolism (VTE) but a significantly increased risk of arterial thromboembolism (ATE) (Peto OR: 1.58 [95% CI: 1.21-2.06]) compared with non-ICI regimens. Stratified by different regimens, only PD-L1 (programmed cell death ligand 1) inhibitors showed a significant increase in ATE (Peto OR: 2.07 [95% CI: 1.26-3.38]). The incidence of VTE was higher in PD-1/PD-L1 inhibitor and CTLA-4 (cytotoxic T lymphocyte antigen 4) inhibitor combination therapies compared with monotherapies (Peto OR: 2.23 [95% CI: 1.47-3.37]). Stratified by tumor, for pulmonary embolism (PE) and cerebral ATE, the statistically significant results were only seen in lung cancer patients (Peto OR: 1.42 [95% CI: 1.02-1.97]; Peto OR: 2.10 [1.07-4.12]), and for myocardial infarction, the statistically significant result was only seen in other tumor types (Peto OR: 2.66 [95% CI: 1.68-4.20], p < 0.0001).

CONCLUSION

 There was no significant increase in the overall risk of VTE in patients treated with ICIs; however, special attention should be given to the risk of VTE in PD-1/PD-L1 inhibitor and CTLA-4 inhibitor combination therapy and PE in lung cancer patients. PD-L1 inhibitors were associated with a significant increase in ATE.

Old is new again: emergence of thromboembolic complications in cancer patients on immunotherapy

Cancer immunotherapy has emerged as one of the most important new treatments for cancer in many years, moving rapidly to front-line therapy for several cancers. Cancer immunotherapy is based on treatment with immune checkpoint inhibitors (ICI), which are monoclonal antibodies directed toward immunoregulatory proteins including PD-1, PD-L1 and CTLA-4. ICI inhibit interactions between these proteins and their ligands, disabling physiologic immune regulatory networks and enhancing anti-tumor immunity. However, since the immune response cannot be directed specifically to the tumor, ICI are associated with immune-related adverse events (irAEs) resulting from immune-mediated attack of normal tissues. We and others have reported a high incidence of thrombosis in patients treated with ICI, which may approach 20%. Given the rapidly increasing use of ICIs, it is clear that ICI-Associated Thrombosis (IAT) is a major emerging clinical problem. However, there is a remarkable knowledge gap concerning mechanisms of IAT. IAT may be a composite irAE resulting from activation of blood and vascular cells, leading to thromboinflammation. Cancer itself is an inflammatory disorder, and inducing further inflammation through ICI administration may stimulate procoagulant activity by multiple cell types. Moreover, some blood and vascular cells express ICI target proteins. Here, we review the results of several studies describing the clinical manifestations of IAT, as well as our recent studies demonstrating that elevated levels of myeloid derived suppressor cells and inflammatory cytokines may serve as biomarkers of IAT. It is hoped that the concepts reviewed here may stimulate further research into this important clinical problem.