Radiological patterns of tumour progression in patients treated with a combination of immune checkpoint blockers and antiangiogenic drugs.

Background: Immune checkpoint blockers (ICBs) in combination with antiangiogenic drugs showed synergistic efficacy in several tumour types. New patterns of progression have recently been defined upon treatment with ICB alone including atypical responses such as pseudoprogression (PsPD), dissociated response and hyperprogressive disease (HPD). This study aimed to describe the patterns of response observed in patients treated with combination ICB with antiangiogenic drugs.

Methods: We conducted a monocentric retrospective analysis of patients (pts) enrolled in phase I trials at Gustave Roussy assessing the combination of ICB and antiangiogenic drugs. Radiological CT scans were centrally reviewed by a senior radiologist according to iRECIST criteria including progressive disease (PD), partial response (PR) and stable disease (SD). HPD was defined as a progression at the first evaluation with a delta tumour growth rate exceeding 50%. PsPD was defined as initial progression followed by stabilisation or decrease of tumour size, DisR as a concomitant size decrease in some tumour lesions and size increase in others. Both PsPD and DisR are defined as atypical responses. Overall response rate included PR and complete response (CR) and disease control rate included PR, CR and SD.

Results: Between December 2016 and June 2020, 111 pts were included. The median follow up was 12.8 months (11.3-15.1). The most common tumour types were lung and pleura (20%), kidney (18%) and bladder (17%). The overall response rate and disease control rate were 21.6% (n = 24) and 59% (n = 65), respectively. Twenty-one patients (19%) experienced PD as the best response. PsPD, DisR and HPD were observed in 4 (3.6%), 11 (9.9%) and 7 (6.3%) pts, respectively. DisR and PsPD were associated with longer iProgression Free Survival (median: 6.9 and 18.9 months, respectively) and iOverall Survival (median: 28.4 and 31.1 months, respectively) than a median of SD in immune progression-free survival (median: 4.2 months) and immune overall survival (median: 12.7 months).

Conclusion: Patients treated with ICBs and antiangiogenic agents display atypical responses. Survival might be longer in patients with DisR responses and PsPD disease than patients with HPD, PD and SD.