Clinical factors influencing retreatment with anti-PD-(L)1 therapies after treatment in early-stage cancers: a modified Delphi consensus study

Anti-programmed death (ligand) 1 (anti-PD-(L)1) therapies were first introduced in the metastatic setting and have since been approved and reimbursed for treating early-stage cancers in the adjuvant, perioperative, and neoadjuvant settings in many cancer types. Current evidence supporting anti-PD(L)-1 retreatment after relapse with prior neoadjuvant and/or adjuvant anti-PD(L)1 therapy is limited and inconclusive. There is no guidance for clinicians on how and when to retreat with anti-PD-(L)1 therapies when anti-PD-(L)1 therapy was administered in the neoadjuvant and/or adjuvant setting. This study aimed to reach consensus on factors to guide decision-making regarding retreatment with anti-PD-(L)1 therapies after prior therapy with an anti-PD-(L)1 agent. This modified Delphi study consisted of a clinician survey across 10 countries followed by three real-time virtual Delphi panels involving clinical experts who had completed the survey. Clinical experts were experienced in using anti-PD-(L)1 treatments in early-stage cancers and/or as retreatment of patients with recurrences following early-stage treatment with anti-PD-(L)1 therapies. Of 28 clinicians providing survey responses, 20 participated in one of three Delphi panels. There was consensus that retreatment can be defined as 'repeated treatment with the same therapeutic class following relapse after or during neoadjuvant and/or adjuvant treatment.' All three panels agreed that decisions around retreatment should consider 'prior immune-related adverse events/toxicity,' 'time-related factors' (eg, time since completion of full treatment course and since discontinuation) and 'previous patient response' (often referred to by clinicians as tumor response, which may have reflected their experience with metastatic disease). Other factors identified as important included country-specific practices, treatment availability, and reimbursement. Generally, the clinical experts considered that retreatment could be considered from ≥3 to 6 months after stopping initial anti-PD-(L)1 treatment, or from ≥6 months after relapse/recurrence. In conclusion, clinicians across different regions recognized a role for retreating patients with anti-PD-(L)1 therapies after initial anti-PD-(L)1 treatment for early-stage cancers. Consensus was reached on some factors to consider regarding whether and when to retreat, although differences in clinical practice between countries/geographical regions made it difficult to achieve consensus for some more nuanced elements of retreatment. Further evidence could help better inform retreatment decisions.