TROPHY-U-01, a phase II open-label study of sacituzumab govitecan in patients with metastatic urothelial carcinoma progressing after platinum-based chemotherapy and checkpoint inhibitors: updated safety and efficacy outcomes.

BACKGROUND: Sacituzumab govitecan (SG) is a Trop-2-directed antibody-drug conjugate containing cytotoxic SN-38, the active metabolite of irinotecan. SG received accelerated US Food and Drug Administration approval for locally advanced (LA) or metastatic urothelial carcinoma (mUC) previously treated with platinum-based chemotherapy and a checkpoint inhibitor, based on cohort 1 of the TROPHY-U-01 study. Mutations in the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene are associated with increased adverse events (AEs) with irinotecan-based therapies. Whether UGT1A1 status could impact SG toxicity and efficacy remains unclear. PATIENTS AND METHODS: TROPHY-U-01 (NCT03547973) is a multicohort, open-label, phase II registrational study. Cohort 1 includes patients with LA or mUC who progressed after platinum- and checkpoint inhibitor-based therapies. SG was administered at 10 mg/kg intravenously on days 1 and 8 of 21-day cycles. The primary endpoint was objective response rate (ORR) per central review; secondary endpoints included progression-free survival, overall survival, and safety. Post hoc safety analyses were exploratory with descriptive statistics. Updated analyses include longer follow-up. RESULTS: Cohort 1 included 113 patients. At a median follow-up of 10.5 months, ORR was 28% (95% CI 20.2% to 37.6%). Median progression-free survival and overall survival were 5.4 months (95% CI 3.5-6.9 months) and 10.9 months (95% CI 8.9-13.8 months), respectively. Occurrence of grade ≥3 treatment-related AEs and treatment-related discontinuation were consistent with prior reports. UGT1A1 status was wildtype (∗1|∗1) in 40%, heterozygous (∗1|∗28) in 42%, homozygous (∗28|∗28) in 12%, and missing in 6% of patients. In patients with ∗1|∗1, ∗1|∗28, and ∗28|∗28 genotypes, any grade treatment-related AEs occurred in 93%, 94%, and 100% of patients, respectively, and were managed similarly regardless of UGT1A1 status. CONCLUSIONS: With longer follow-up, the ORR remains high in patients with heavily pretreated LA or mUC. Safety data were consistent with the known SG toxicity profile. AE incidence varied across UGT1A1 subgroups; however, discontinuation rates remained relatively low for all groups.

Genomic characterization of human SEC14L1 splice variants within a 17q25 candidate tumor suppressor gene region and identification of an unrelated embedded expressed sequence tag.

Human SEC14L1 shows partial sequence homology to the budding yeast SEC14 protein and the Japanese flying squid retinal-binding protein and was previously generally localized to 17q25. We more precisely mapped SEC14L1 within a discrete region of 17q25 that likely harbors at least one putative breast and ovarian tumor suppressor gene. We determined that this gene consists of 18 exons ranging in size from 70 bp (exon 11) to 3088 bp (exon 17) and spanning at least 58 kb of DNA. Exon 17 contained a highly polymorphic variable number of tandem repeats (VNTR) and was present only in the larger ubiquitously expressed 5.5-kb transcript. The 3.0-kb ubiquitously expressed transcript included sequences at the beginning of exon 17 (designated exon 17a) and the end of exon 17 (designated exon 18), but lacked the internal 2439 bp of exon 17, including the VNTR. This alternative splicing resulted in a predicted protein of 719 residues from the smaller transcript with four more terminal amino acids than the 715 residue protein predicted from the larger transcript. EST H49244 spanned exon 11 of SEC14L1 and was specifically expressed in human peripheral blood leukocytes. One intragenic single nucleotide polymorphism (SNP) was confirmed. SEC14L1 contained the CRAL/TRIO domain also found in alpha-tocopherol transfer protein (TTPA) and cellular retinaldehyde-binding protein (CRALBP). As retinoids have been shown to inhibit the growth of breast cancer cells, loss of the proposed SEC14L1 retinal-binding function may contribute to breast tumorigenesis. As TTPA and CRALBP have been implicated in retinitis pigmentosa (RP), altered SEC14L1 expression may contribute to RP in previously unlinked families. Coding exon-specific PCR primers were designed to aid in future expression and mutational analyses.