Background: The transformed growth factor beta (TGF-β) signaling pathway is dysregulated in carcinogenesis. In NPC patients, upregulation of TGF-β pathway is correlated with disease stage or phenotype due to Epstein-Barr virus (EBV) infection. GFH018, a novel TGF-βRI inhibitor, can inhibit tumor growth through inhibiting the activity of TGF-βRI kinase to block the signal transduction of TGF-β and modulate the tumor immune microenvironment. Preclinical studies showed that GFH018 in combination with PD-1/PD-L1 monoclonal antibody can significantly inhibit tumor growth synergistically. Here we report the preliminary results of combining GFH018 and Toripalimab treating R/M NPC patients (pts). Methods: This is a phase Ib/II study to evaluate the safety and efficacy of the combination of GFH018 and Toripalimab in pts with advanced solid tumors. Patients with RM NPC were enrolled to receive GFH018 80mg twice a day (BID) 14-day-on/14-day-off in combination with Toripalimab 3mg/kg every two weeks. Tumor assessment was performed every 8 weeks per Response Evaluation Criteria in Solid Tumor (RECIST) 1.1. Results: As of 31 Dec 2022, 32 pts with R/M NPC who had progressed on at least one prior line therapy were enrolled. Sixteen (50%) had received ≥3 lines of prior therapies, and 19 (59.4%) had previously received immune checkpoint inhibitors (ICIs) and platinum-based chemotherapies. The median duration of study drug exposure was 7 weeks. Twenty-five pts (78.1%) experienced treatment-related adverse events (TRAEs) of any grades, and 11 pts (34.4%) had ≥ Grade 3. The most common TRAEs (occurring in ≥ 3 pts) were anaemia (n = 6, 18.8%), hyponatraemia (n = 6, 18.8%), rash (n = 6, 18.8%), fatigue (n = 4, 12.5%), white blood cell count decreased (n = 4, 12.5%), aspartate aminotransferase increased (n = 3, 9.4%), back pain (n = 3, 9.4%), decreased appetite (n = 3, 9.4%), hypokalaemia (n = 3, 9.4%), and hypothyroidism (n = 3, 9.4%). As of 18 Jan 2023, among the 27 pts with post-baseline tumor assessments, 8 achieved partial response (PR), and 5 stable disease (SD); the overall response rate (ORR) was 29.6%, and disease control rate (DCR) was 48.1%. Six PR and 2 SD were observed among the 12 pts without prior treatment of ICIs; the ORR was 50%, and DCR was 66.7%. Four pts discontinued treatment without any post-baseline tumor assessments due to AEs or withdrawal of consent, and 1 patient is premature for tumor assessment. Conclusions: GFH018 combined Toripalimab was well tolerated and demonstrated preliminary efficacy in pts with R/M NPC. Specifically, in pts who had not previously received ICIs, promising antitumor activity was observed supporting further investigation to this group of pts. Clinical trial information: NCT04914286.