Clinical Activity and Pharmacokinetics (PK) of Cabozantinib (XL184) in Patients with Progressive Medullary Thyroid Carcinoma (MTC)

Cabozantinib for the treatment of solid tumors: a systematic review

Background:

Cabozantinib is approved, in various settings, for the treatment of renal cell carcinoma, medullary thyroid cancer, and hepatocellular carcinoma, and it has been investigated for the treatment of other cancers. With the available evidence and the real-world performance of cabozantinib compared with clinical trial data, we performed a systematic review of cabozantinib monotherapy as treatment for solid tumors in adults.

Methods:

This study was designed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses and registered with PROSPERO (CRD42020144680). We searched for clinical and observational studies of cabozantinib monotherapy for solid tumors using Embase, MEDLINE, and Cochrane databases (October 2020), and screened relevant congress abstracts. Eligible studies reported clinical or safety outcomes, or biomarker data. Small studies (n < 25) and studies of cabozantinib combination therapies were excluded. Quality was assessed using National Institute for Health and Care Excellence methodology, and study characteristics were described qualitatively.

Results:

Of 2888 citations, 114 were included (52 randomized studies, 29 observational studies, 32 nonrandomized phase I or II studies or pilot trials, and 1 analysis of data from a randomized study and a nonrandomized study). Beyond approved indications, other tumors studied were castration-resistant prostate cancer, urothelial carcinoma, Ewing sarcoma, osteosarcoma, uveal melanoma, non-small-cell lung cancer, Merkel cell carcinoma, glioblastoma, pheochromocytomas and paragangliomas, cholangiocarcinoma, gastrointestinal stromal tumor, colorectal cancer, salivary gland cancer, carcinoid and pancreatic neuroendocrine tumors, and breast, endometrial and ovarian cancers. The most common adverse events were hypertension, diarrhea, and fatigue.

Conclusion:

The identified evidence demonstrates the positive efficacy/effectiveness of cabozantinib monotherapy in various solid tumor types, with safety findings being consistent with those observed with other VEGFR-targeting tyrosine kinase inhibitors. When available, real-world findings were consistent with the data reported from clinical trials. A limitation of this review is the high proportion of abstracts; however, this allowed us to capture the most up-to-date findings.

Cabozantinib and vandetanib for unresectable locally advanced or metastatic medullary thyroid cancer: a systematic review and economic model

BACKGROUND

Medullary thyroid cancer (MTC) is a rare form of cancer that affects patients' health-related quality of life (HRQoL) and survival. Cabozantinib (Cometriq^®; Ipsen, Paris, France) and vandetanib (Caprelsa^®; Sanofi Genzyme, Cambridge, MA, USA) are currently the treatment modality of choice for treating unresectable progressive and symptomatic MTC.

OBJECTIVES

(1) To evaluate the clinical effectiveness and safety of cabozantinib and vandetanib. (2) To estimate the incremental cost-effectiveness of cabozantinib and vandetanib versus each other and best supportive care. (3) To identify key areas for primary research. (4) To estimate the overall cost of these treatments in England.

DATA SOURCES

Peer-reviewed publications (searched from inception to November 2016), European Public Assessment Reports and manufacturers' submissions.

REVIEW METHODS

A systematic review [including a network meta-analysis (NMA)] was conducted to evaluate the clinical effectiveness and safety of cabozantinib and vandetanib. The economic analysis included a review of existing analyses and the development of a de novo model.

RESULTS

The systematic review identified two placebo-controlled trials. The Efficacy of XL184 (Cabozantinib) in Advanced Medullary Thyroid Cancer (EXAM) trial evaluated the efficacy and safety of cabozantinib in patients with unresectable locally advanced, metastatic and progressive MTC. The ZETA trial evaluated the efficacy and safety of vandetanib in patients with unresectable locally advanced or metastatic MTC. Both drugs significantly improved progression-free survival (PFS) more than the placebo (p < 0.001). The NMA suggested that, within the symptomatic and progressive MTC population, the effects on PFS were similar (vandetanib vs. cabozantinib: hazard ratio 1.14, 95% credible interval 0.41 to 3.09). Neither trial demonstrated a significant overall survival benefit for cabozantinib or vandetanib versus placebo, although data from ZETA were subject to potential confounding. Both cabozantinib and vandetanib demonstrated significantly better objective response rates and calcitonin (CTN) and carcinoembryonic antigen (CEA) response rates than placebo. Both cabozantinib and vandetanib produced frequent adverse events, often leading to dose interruption or reduction. The assessment group model indicates that, within the EU-label population (symptomatic and progressive MTC), the incremental cost-effectiveness ratios (ICERs) for cabozantinib and vandetanib are > £138,000 per quality-adjusted life-year (QALY) gained. Within the restricted EU-label population (symptomatic and progressive MTC with CEA/CTN doubling times of ≤ 24 months), the ICER for vandetanib is expected to be > £66,000 per QALY gained. The maximum annual budget impact within the symptomatic and progressive population is estimated to be ≈£2.35M for cabozantinib and ≈£5.53M for vandetanib. The costs of vandetanib in the restricted EU-label population are expected to be lower.

LIMITATIONS

The intention-to-treat populations of the EXAM and ZETA trials are notably different. The analyses of ZETA subgroups may be subject to confounding as a result of differences in baseline characteristics and open-label vandetanib use. Attempts to statistically adjust for treatment switching were unsuccessful. No HRQoL evidence was identified for the MTC population.

CONCLUSIONS

The identified trials suggest that cabozantinib and vandetanib improve PFS more than the placebo; however, significant OS benefits were not demonstrated. The economic analyses indicate that within the EU-label population, the ICERs for cabozantinib and vandetanib are > £138,000 per QALY gained. Within the restricted EU-label population, the ICER for vandetanib is expected to be > £66,000 per QALY gained.

FUTURE RESEARCH PRIORITIES

(1) Primary research assessing the long-term effectiveness of cabozantinib and vandetanib within relevant subgroups. (2) Reanalyses of the ZETA trial to investigate the impact of adjusting for open-label vandetanib use using appropriate statistical methods. (3) Studies assessing the impact of MTC on HRQoL.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016050403.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.