Stereotactic body radiotherapy combined with immunotherapy or targeted therapy: a screenshot from Italy on behalf of the Italian Association of Clinical Oncology and Radiotherapy (AIRO)

Aim: Despite the widespread use of immunotherapy (IO) and targeted therapy (TT) in clinical practice, data on toxicity in combination with SBRT are lacking, largely based on retrospective studies and case reports. The present survey, conducted within the AIRO Oligometastatic Study Group, was developed for radiation oncologists to investigate the current clinical practice in Italy regarding hypofractionated SBRT (defined as a dose/fraction ≥ 5 Gy) in cancer patients using IO and TT. Methods: The online survey, composed of 19 questions, was developed using the cloud-based platform SurveyMonkey® and was sent to all registered AIRO members using the association's mailing list and was administered online and in anonymous form. Results: Sixty-eight AIRO members from different Italian regions completed the proposed survey. 59% stated that there is sufficient knowledge within their institute regarding the potential interaction between SBRT and TT/IO. According to 76% of the pool, a multidisciplinary protocol is available in their institute. However, 50% of participants report that interdisciplinary consultation with a radiation oncologist did not always take place. Only 6% of the radiation oncologists stated that they lacked sufficient knowledge to adequately consider the treatment of these patients, while 81% of them felt confident in deciding whether or not to combine SBRT and IO/TT. The 26% and the 37% answered that TT and IO, respectively, should be stopped during RT administration. Regarding which drug types would be of concern when patients are referred for SBRT, the majority of the answers regarded ALK inhibitors (21%), BRAF inhibitors (25%), EGFR inhibitors (26%), immune checkpoint inhibitors (25%) and PARP inhibitors (25%). Only 5% did not consider any of these classes of drugs. Particularly, many radiation oncologists (19%) did not expect a real risk of tumor flare upon discontinuation of TT or IO. Conclusion: The findings from the present survey underscore significant variability in clinical practice regarding the combination of SBRT with IO and TT across Italy. Therefore, there is an urgent need for prospective clinical studies to evaluate the safety and efficacy of combining SBRT with IO/TT. These studies should aim to generate robust data that can inform the development of comprehensive, evidence-based guidelines.