This is a phase I/II basket study of solid tumors who received SG on days 1 and 8 of 21-day cycles until progression or toxicity. Patients were radiographically restaged every 8 weeks. This abstract describes the 45 patients who were treated with SG.
The median age was 67 and all patients had at least one prior line of systemic therapy. The majority of patients were men 41/45 and almost all patients (95%) had platinum-based chemotherapy previously. 38% of patients had been previously treated with a checkpoint inhibitor. This was a high risk population – 33/45 had visceral metastases, most commonly to the lung (15/45) and liver (27/45).
The median duration of follow up at the data cut-off was 15.7 months. Patients have had a median of 8 treatment cycles and 20% of patients have been treated for over one year. 5 patients remain on treatment, one of which was treated through progression and achieved a complete response.
The objective response rate was 31% overall, with 2/45 complete responses and 12 partial responses. In patients who had been previously treated with an immune checkpoint inhibitor, the ORR was 23% (4/17). The median duration of response was 12.6 months and 2 patients remain on therapy for over 2 years. The median overall survival was 18.9 months.
In terms of safety, the most common grade 3/4 adverse events were neutropenia (38%), anemia (11%), hypophosphatemia (11%), diarrhea (9%), fatigue (9%), and febrile neutropenia (7%). 5/45 patients discontinued treatment due to adverse events and no treatment-related deaths have been reported.
SG is a promising new agent for patients with metastatic UC who have progressed after one line of therapy. The median OS described in this small study compares favorably to other second-line UC trials and a single arm, open label, global phase II study is underway to further evaluate safety and efficacy.
Presented by: Scott T. Tagawa, MD, MS, Weill Cornell Medicine, Assistant Professor of Medicine and Urology and Assistant Attending Physician in the Division of Hematology and Medical Oncology.
Written By: Jason Zhu, MD. Fellow, Division of Hematology and Oncology, Duke University, Twitter: @TheRealJasonZhu at the 2019 American Society of Clinical Oncology Genitourinary Cancers Symposium, (ASCO GU) #GU19, February 14-16, 2019 - San Francisco, CA
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