ESTRO meets Asia 2024 - Abstract Book

S35

Invited Speaker

ESTRO meets Asia 2024

The PACIFIC trial is the first phase III trial that showed adjuvant durvalumab improved both progression-free survival (PFS) and overall survival (OS) after concurrent chemoradiation for unresectable stage III non-small cell lung cancers (NSCLC). The recently reported interim results of ADRIATIC trial also showed adjuvant durvalumab improved survival (PFS and OS) after concurrent chemoradiotherapy for limited stage small cell lung cancers (SCLC). However, the risk of pneumonia and radiation pneumonitis is increased in patients receiving IO. In esophageal carcinoma, Checkmate 577 study showed that patient who did not achieve pathological complete remission after neoadjuvant chemoradiation had significant improvement in PFS with adjuvant nivolumab after surgery. These studies showed that IO as consolidative treatment after concurrent chemoradiotherapy to control loco-regional disease is effective in reducing relapse and improving survival. However, these studies include all comers, predictive biomarkers to select patient who will benefit from such expansive, prolonged treatment are required. This is highlighted by the recent report of the LAURA trial which showed that adjuvant osimertinib improved PFS after chemoradiotherapy for unresectable EGFR mutated NSCLC. It is expected that adjuvant treatment will be guided by biomarkers in the future. On the other hand, neoadjuvant use of chemotherapy and IO followed by surgery in resectable NSCLC have been shown to achieve higher complete pathological response rate and better event-free survival compared with neoadjuvant chemotherapy. The use of neoadjuvant chemotherapy and IO achieved complete pathological response of 17.2-25.3% in different trials. Thus it is an effective downstaging strategy and may be considered in unresectable NSCLC also. The standard treatment for loco-regionally advanced head and neck cancers (HNSCC) is concurrent chemoradiation. KEYNOTE 412 is a randomized controlled trial comparing pembrolizumab or placebo in combination with chemoradiation for locally advanced HNSCC. Pembrolizumab/placebo was started 1 week before chemoradiation, concurrent with chemoradiation and as adjuvant treatment for total 1 year. Pembrolizumab and chemoradiation did not improve event-free survival compared with chemoradiation. This is a molecularly unselected population. The clinical benefit of pembrolizumab appears to increase with PD-L1 expression, suggesting that PD-L1 may be a useful biomarker. Further trials would evaluate sequential treatment or PD-L1 selected population. Extensive irradiation, especially in combination with chemotherapy can induce immunosuppression. In contrast, stereotactic body radiotherapy (SBRT) has been suggested to more likely induce immune response. The combination of SBRT with immunotherapy has been explored in different diseases. Preliminary results showed high complete pathological response after SBRT and immunotherapy in head and neck cancers. High conversion rate was achieved in unresectable HCC with combination of transarterial chemoembolization, SBRT and immunotherapy.

Thus, the correct sequence of combination of IO with RT may depend on the disease type, timing of IO after RT, molecular subtype and radiation technique.

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How to treat rectal cancer in 2024?

Karin Haustermans

Radiation Oncology, UZ KULeuven, Leuven, Belgium

Abstract

Over the last decade, there has been a huge evolution in how we treat rectal cancer today. The results of several phase 3 trials were reported. Based on these, the treatment of locally advanced rectal cancers was intensified where chemotherapy is now given in addition to (chemo)radiotherapy before total mesorectal excision (TME). We call this