ETA2023 Poster Presentations Treatment 1 (9 abstracts)
Comparative effectiveness of selpercatinib vs standard treatment in patients with medullary thyroid cancer: An interpatient analysis from libretto-001
Lori Wirth 1 , Francis Worden 2 , John Morris 3 , Jacques Medioni 4 , Barbara Deschler-Baier 5 , Yimei Han 6 , Urpo Kiiskinen 6 , Min-Hua Jen 6 , Scott Barker 6 , Sylwia Szymczak 6 & Adrienne Gilligan 6
1Department of Medicine, Massachusetts General Hospital, Boston, MA, USA, Massachusetts General Hospital, Boston, United States; 2University of Michigan, Department of Internal Medicine, Medical Oncology, Ann Arbor, MI, United States; 3Mayo Clinic, Division of Endocrinology, Mayo Building, 18th Floor, Rochester, Mn, United States; 4European Hospital Georges Pompidou, Paris, France; 5CCC Mf, Würzburg, Germany; 6Eli Lilly and Company, Indianapolis, United States
Objective: Head-to-head data comparing selpercatinib, a highly selective and potent RE arranged during Transfection (RET) kinase inhibitor with CNS activity, to standard treatment of RET-altered medullary thyroid cancer (MTC; cabozantinib or vandetanib) is currently unavailable. This post-hoc comparative effectiveness analysis of data from the phase 1/2 LIBRETTO-001 trial compared investigator-assessed outcomes among patients with RET-mutated MTC treated with selpercatinib, but naïve to cabozantinib and/or vandetanib (selpercatinib arm), vs outcomes among patients previously treated with cabozantinib and/or vandetanib, who may have also received other systemic therapy including multikinase inhibitors (MKI) in first-line (1L) prior to trial enrollment (comparator arm).
Methods: Data obtained from case report forms in the LIBRETTO-001 trial (15 June 2021, data cutoff date) were assessed retrospectively. Patients aged ≥12 years, diagnosed with advanced or metastatic RET-mutated MTC, and Eastern Cooperative Oncology Group Performance Status score 0 to 2 were included. The index date was the date of initiation of selpercatinib treatment for the selpercatinib arm and the date of initiation of 1L MKI treatment for the comparator arm. Time to treatment discontinuation (TTD), time to next treatment or death (TTNT-D), and time to progression (TTP) were compared between the cohorts after propensity score-based matching (1:1 using baseline covariates) to estimate treatment effect. Kaplan-Meier analyses with log-rank test were performed for TTD, TTNT-D, and TTP, followed by Cox proportional hazards regression model to estimate relative efficacy, presented as hazard ratios (HR) and 95% confidence intervals (CI).
| Outcome in months | Selpercatinib arm, median (95% CI) (n =135) | Comparator arm, median (95% CI) (n =135) | HR (95% CI) | P-value |
| TTD | Not reached (NR, NR) | 14.0 (11.8, 16.7) | 0.13 (0.08, 0.20) | <0.0001 |
| TTNT-D | Not reached (NR, NR) | 16.1 (14.0, 18.8) | 0.03 (0.01, 0.08) | <0.0001 |
| TTP | Not reached (NR, NR) | 15.2 (12.6, 18.0) | 0.11 (0.06, 0.18) | <0.0001 |
| NR – Not Reached | ||||
Results: From the 277 total patients, 142 and 135 were included in the selpercatinib arm and comparator arm, respectively. Both the arms had 135 patients after matching. Overall, baseline patient characteristics were similar between the arms after matching, except for brain metastases (selpercatinib arm 2.2% vs comparator arm 7.4%; P < 0.05). The selpercatinib arm demonstrated significantly longer TTD (HR 0.13 [95% CI 0.08, 0.20]), TTNT-D (HR 0.03 [95% CI 0.01, 0.08]), and TTP (HR 0.11 [95% CI 0.06, 0.18]) than the comparator arm.
Conclusion: The current analysis suggests selpercatinib use is associated with improved outcomes and may be more efficacious compared to standard therapies for patients with advanced or metastatic RET-mutated MTC. Further information will be obtained from the ongoing phase 3 LIBRETTO-531 trial.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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