ESMO Magnitude of Clinical Benefit Scale (MCBS): An evaluation of systemic treatment trials for soft tissue sarcomas (STS).

Abstract

11553 Background: Patients with STS have poor prognosis in the metastatic setting. Although some treatment options are associated with improved outcomes, such as progression-free (PFS) or overall survival (OS), the overall magnitude of clinical benefit can be unclear. The ESMO MCBS is a validated and reproducible tool developed to quantify the clinical benefit of treatments evaluated in trials ( www.esmo.org/guidelines/esmo-mcbs ). Herein, we report the application of ESMO MCBS to systemic treatment trials involving metastatic STS patients. Methods: A systematic search of Medline, Embase and Cochrane databases for adult phase II and III trials in advanced STS (01/1998 to 12/2020) was carried out. Gastrointestinal stromal tumor trials were excluded. Outcomes, including but not limited to OS, PFS, objective response rate (ORR), toxicity and quality of life (QoL) data were extracted and analyzed. Studies with outcomes that met the criteria for ESMO MCBS v1.1 were evaluated to generate a score of 1 to 5 (score of ≥ 4: substantial benefit). MCBS scoring of each study was performed by at least 2 co-authors for consensus. Results: Among 3454 abstracts screened, a total of 140 Phase II and 28 phase IIII trials were identified. A total of 41 studies fulfilled the criteria for ESMO MCBS scoring. These include 5 phase III studies, as well as 9 randomized and 27 single-arm phase II trials. Fifteen studies involved specific histology, while remaining 26 studies were of all STS subtypes. Chemotherapy, alone or in combination was evaluated in 29 trials, while molecular-targeted agents (MTA) and immune checkpoint inhibitors (IO) were evaluated in 11 and 3 studies, respectively (Table). The median MCBS score was 2 (range 1-4), regardless of drug class or combination. Only 3 studies, all randomized in design, had a MCBS score of 4. All three trials were in the 2nd line setting or beyond, where there is no standard control treatment. None of the trials, irrespective of drug class had a score of 5 and no study showed evidence of significant improvement in QoL. The observed MCBS scores were low, partly because the trials evaluated mainly comprise single-arm studies without QoL assessments, restricting to a maximum MCBS score of 3. Conclusions: Most systemic therapy trials in advanced STS did not confer substantial clinical benefit when evaluated using MCBS. Although randomized phase 3 trials remain the gold standard of treatment evaluation, clinical benefit evaluation of STS trials using tools such as MCBS may be useful. Incorporation of QoL evaluation, even in single-arm studies should be prioritized in metastatic STS trials.[Table: see text]