Response Efficacy of PD-1 and PD-L1 Inhibitors in Salivary Gland Cancers: A Systematic Review and Meta Analysis

Zahra Babamohamadi ¹ Amirreza Taherkhani ¹ Ali Yousefzadeh ² Ali Moradi ³ Marziyeh Heidari ⁴ Zahra Sadat Hoseini Nasab ⁵ Seyedeh Mona Haghi ⁶ Ayda Afkhami ² Mohaddeseh Belbasi ⁷ Masoud Noroozi ^8* Niloofar Deravi ^1*

• ¹ Shahid Beheshti University of Medical Sciences, Tehran, Iran
• ² Tabriz University of Medical Sciences, Tabriz, Iran
• ³ Centre for Translational Medicine, Semmelweis University, Budapest, Hungary
• ⁴ Hormozgan University of Medical Sciences, Bandar Abbas, Hormozgān, Iran
• ⁵ Mashhad University of Medical Sciences, Mashhad, Razavi Khorasan, Iran
• ⁶ School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
• ⁷ Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Zanjan, Iran
• ⁸ Department of Biomedical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Isfahan, Iran

Background: Salivary gland carcinoma (SGC) is an infrequent malignancy characterized by various pathological subtypes. Immune checkpoint inhibitors (ICIs) have emerged as promising therapeutic strategies for several cancers. Evidence suggests that ICIs may be effective against rare neoplasms, including SGC. This meta-analysis evaluated the efficacy of PD-1 and PD-L1 inhibitors in treating salivary gland cancers.Method: A thorough search was conducted in PubMed, Scopus, and Google Scholar databases up to February 24, 2024. Related articles were extracted titles, abstract and full text were screened. The quality of the included articles were asses. The data was extracted, and the hens were analyzed. The research protocol of this systematic review and meta-analysis was registered on the Prospero website.Result: Altogether, a total of 5 cohort studies and 3 randomized controlled trials (RCT) with a total of 532 populations were included in these meta-analyses . These studies were conducted in the USA, Japan, France, and China. The average age of patients was between 53-67 years. Our analyses showed an increase in progression-free survival in cohort studies and RCTs, the pulled effect is 1.12 (95% CI 1-1.25) and 1.14 (95% CI 1.07-1.20), respectively, in patients with SGC who received PD-1 and PD-L1 inhibitors.This meta-analysis suggests that PD-1 and PD-L1 inhibitors in patients with salivary gland cancer can significantly increase progression-free survival of SGC. Due to the high heterogeneity of the studies, further largest RCTs are required to prove the association.