Immunotherapy Tolerance in Older Adults With Cancer

Abstract

Immunotherapy has revolutionized cancer treatment, yet its application in older adults presents unique challenges and opportunities. Age-related changes in immunity, comorbidities, and polypharmacy can influence both the efficacy and tolerability of immunotherapeutic agents. This review synthesizes recent evidence and clinical guidelines on immunotherapy tolerance in the elderly, examining the epidemiology, pathophysiology, risk factors, clinical features, diagnostic considerations, management strategies, emerging therapies, and guideline recommendations to provide a comprehensive resource for healthcare professionals managing older adults with cancer.

Introduction

The advent of immunotherapy, notably immune checkpoint inhibitors (ICIs), has dramatically altered the oncologic landscape, offering hope for durable responses in various malignancies. However, the question of how older adults tolerate these therapies remains clinically significant. With a growing aging population and a rising incidence of cancer in this demographic, understanding the nuances of immunotherapy in older adults is essential for optimizing outcomes while minimizing harm.

Epidemiology / Disease Burden

Globally, cancer predominantly affects older adults, with over 60% of malignancies diagnosed in individuals aged 65 years and above. The increased life expectancy and demographic shift contribute to a substantial disease burden in geriatric populations. Immunotherapy use in this cohort is rising, but real-world data indicate that older adults remain underrepresented in pivotal clinical trials. This underrepresentation complicates risk-benefit assessments and the generalizability of trial results to routine clinical practice.

Pathophysiology

Immunosenescence—the gradual deterioration of the immune system with age—affects both innate and adaptive immunity. T-cell repertoire diversity declines, antigen-presenting cell function diminishes, and inflammatory profiles shift toward chronic low-grade inflammation (inflammaging). These alterations can affect both the antitumor potency and the immune-related adverse event (irAE) profile of immunotherapies. Additionally, age-associated organ dysfunction and altered pharmacokinetics may further impact drug metabolism and systemic exposure to immunotherapeutic agents.

Risk Factors

Older adults present with a spectrum of risk factors that may modulate immunotherapy tolerance. Key considerations include multimorbidity, frailty, decreased organ reserves, and polypharmacy, which can predispose to increased toxicity and drug-drug interactions. Geriatric syndromes, such as cognitive impairment and functional decline, may hinder prompt recognition and management of irAEs. Moreover, specific cancer types and preexisting autoimmune conditions may further elevate the risk of adverse outcomes during immunotherapy.

Clinical Features

The clinical manifestation of immunotherapy tolerance in older patients can be heterogeneous. While some tolerate ICIs comparably to younger adults, others may experience heightened susceptibility to irAEs, including dermatologic, gastrointestinal, hepatic, endocrine, and pulmonary toxicities. Older adults may also exhibit atypical presentations, such as delirium or nonspecific constitutional symptoms, complicating diagnosis and timely intervention. Early recognition of irAEs, with attention to geriatric-specific presentations, is crucial for effective management.

Diagnosis

Diagnosis of immunotherapy-related toxicity in older adults requires a high index of suspicion and a multidisciplinary approach. Comprehensive geriatric assessment (CGA) can aid in baseline evaluation and risk stratification. Laboratory monitoring, organ function assessment, and imaging studies should be tailored to the patient's comorbidities and performance status. Importantly, clinicians must distinguish irAEs from age-related comorbidities, disease progression, or concomitant medication effects, which often overlap in this population.

Treatment & Management

Management of immunotherapy in older adults necessitates individualized risk-benefit analyses. Dose adjustments of ICIs are generally not required based on age alone but may be considered in the context of organ dysfunction. Prompt identification and management of irAEs, including corticosteroid or immunosuppressive therapy, are critical. Supportive care, rehabilitation, and coordination with geriatricians can enhance tolerability. Polypharmacy review and deprescribing strategies are recommended to minimize drug-drug interactions and optimize therapeutic outcomes.

Recent Advances / Emerging Therapies

Recent studies have explored biomarkers for predicting immunotherapy response and toxicity, such as tumor mutational burden, PD-L1 expression, and immune gene signatures. Novel agents and combination regimens, including bispecific antibodies and personalized vaccines, are under investigation for their potential to improve efficacy with manageable toxicity profiles in older adults. Geriatric-specific clinical trials and real-world registries are providing much-needed data to inform patient-centered care in this evolving field.

Guideline Recommendations

International guidelines now emphasize the importance of CGA for all older adults considered for immunotherapy. The American Society of Clinical Oncology (ASCO) and the European Society for Medical Oncology (ESMO) recommend multidisciplinary evaluation, proactive irAE monitoring, and early intervention strategies. Shared decision-making, involving patients and caregivers, is encouraged to align therapeutic goals with patient preferences and quality of life considerations.

Conclusion

Immunotherapy represents a transformative option for older adults with cancer, but its successful implementation requires careful consideration of age-related physiological changes, comorbidities, and patient values. Recent evidence highlights that age alone should not preclude immunotherapy, but vigilant risk assessment and tailored management are essential. Ongoing research and guideline development will further refine strategies to maximize benefit and minimize harm, ensuring equitable access to life-extending therapies for the aging cancer population.