Atypical Response Patterns in Patients Treated With Nivolumab

Area of Science:

• Oncology
• Immunotherapy
• Radiology

Background:

• Programmed cell death protein-1 (PD-1) inhibitors like nivolumab are used in cancer treatment.
• Assessing treatment response is critical for patient management and clinical decision-making.

Purpose of the Study:

• To determine the frequency of atypical response patterns in oncology patients treated with nivolumab.
• To identify different types of atypical responses to PD-1 inhibitor therapy.

Main Methods:

• Retrospective analysis of 254 patients treated with nivolumab from January 2013 to August 2017.
• Blinded reader assessment of treatment response, categorizing responses into four patterns.
• Atypical response patterns included specific increases in the sum of the longest dimension (SLD) or new lesion development.

Main Results:

• Among 166 patients with clinical benefit, 20% exhibited atypical response patterns (Patterns 2, 3, or 4).
• Classic pseudoprogression (Pattern 3) was rare (1%), while new lesions (Pattern 4) occurred in 10%.
• Atypical responses were more frequent in patients receiving nivolumab and ipilimumab combination therapy (27%).

Conclusions:

• Atypical response patterns are observed in a significant proportion (20%) of patients benefiting from nivolumab.
• Delayed responses, potentially up to 24 months, can occur.
• Radiologists must recognize these atypical patterns to prevent misinterpretation of treatment efficacy.