Hypocalcemia induced by tyrosine kinase inhibitors: targeted treatment with 'untargeted' side effects

Reporting of tumor lysis syndrome with targeted therapy for hepatic cancer in the FDA adverse events reporting system

BACKGROUND

Hepatic cancer is a common cancer in clinical practice. Current drug therapies for this condition include targeted therapy, chemotherapy, and immunotherapy. Tumor lysis syndrome (TLS) is the most serious complication of oncology treatment. According to the literature, several cases reported TLS occurred with targeted therapies for hepatic cancer.

METHODS

Reporting odds ratio and information component were used to measure the disproportionate signals for TLS associated with targeted therapies, using data from the FDA's Adverse Event Reporting System (FAERS). A stepwise sensitivity analysis was conducted to test the robustness of signals. Time-to-onset analysis was used to describe the latency of TLS events associated with targeted therapies. The Bradford Hill criteria were used to perform a global assessment of the evidence.

RESULTS

Sorafenib, lenvatinib, cabozantinib, and bevacizumab showed higher disproportionate signals for TLS than chemotherapy. The median number of days to TLS occurrence after drug therapy was 5.5, 6.5, and 6.5 days for sorafenib, lenvatinib, and bevacizumab, respectively.

CONCLUSIONS

There is a significant association between tumor lysis syndrome and targeted therapies for hepatic carcinoma, with particularly strong signals for sorafenib and lenvatinib. Clinicians should be aware of the potential for tumor lysis syndrome in targeted therapies for hepatic carcinoma.

Hypocalcemia During Lenvatinib Treatment for Advanced Thyroid Cancer: Clinical Features and Management in a Real-Life Setting

Background: Several toxicities are recorded during treatment of advanced thyroid cancer (TC) with antiangiogenic drugs, including lenvatinib (LEN). Hypocalcemia was reported in registration studies, but little data are available from real-life cohorts. The aim of our study was to describe the incidence, characteristics, and the management of hypocalcemia in patients on LEN treatment. Methods: This is a retrospective cohort study of consecutive patients with advanced TC, treated with LEN for at least six months at a single tertiary center in Italy. Phosphocalcic metabolism was evaluated during treatment. Results: We included 25 patients treated for a mean of 29 ± 19 months (range 6-68 months). Hypocalcemia occurred in 6 of the 25 patients (24% [95% confidence interval 9.36-45.13%]), being of grade ≥3 in 2 of the 25 patients (8%), and recurrent in 4 of 6 patients (67%). The median time to hypocalcemia onset was 3 months (range 0.5-13 months) from starting LEN. No differences were found between patients who developed or not hypocalcemia regarding either starting/mean dose of LEN or clinicopathological characteristics. During the hypocalcemic crisis, the 2 patients with grade ≥3 hypocalcemia had low magnesium and low or inappropriately normal parathormone (PTH) levels, while 2 of 3 patients with grade 2 hypocalcemia had a secondary hyperparathyroidism. Hypocalcemia was managed with calcium oral supplementation in most cases, although up to 10% of patients required intravenous calcium treatment and transient LEN withdrawal. Conclusions: In this relatively small cohort, we observed an incidence of hypocalcemia of 24%, which is higher than that reported in the registration trial (6.9%). Both PTH-dependent and PTH-independent mechanisms explained hypocalcemia in the present cohort. Monitoring of serum calcium levels is strongly advised during the first year of LEN treatment, as hypocalcemia may be severe. More research is needed to confirm our findings and inform possible risk factors for hypocalcemia in advanced TC patients treated with LEN.

Lenvatinib-induced hypocalcaemia due to transient primary hypoparathyroidism

CONTEXT

Radioiodine refractory differentiated thyroid cancer can be effectively treated with multi-tyrosine-kinase inhibitors (MKIs). Hypocalcaemia has been reported among the side effects of these drugs, but little is known about its pathophysiology and clinical relevance.

CASE REPORT

We report the case of a 78-years-old woman with an aggressive papillary thyroid cancer infiltrating perithyroidal structures. The extent of surgery was limited to hemithyroidectomy, RAI treatment could not be performed, and she started lenvatinib treatment. After 4 months of therapy, the patient accessed the Emergency Department for a grade III hypocalcaemia (corrected serum calcium: 6.6 mg/dL, n.v. 8.1-10.4 mg/dL), due to primary hypoparathyroidism (serum PTH: 12.6 ng/L, n.v. 13-64 ng/L). The patient was treated with intravenous calcium infusions and vitamin D supplementation. After discharge, the oral dose of carbonate calcium (CaCO₃) was of 6 g/day, and was titrated according to blood exams. Two weeks after discharge, while taking CaCO₃ at the dose of 3 g/day, the patient experienced symptomatic grade II hypercalcemia (corrected serum calcium: 11.6 mg/dL), associated to the spontaneous reprise of PTH secretion, and leading to oral calcium withdrawal. During the subsequent follow-up, the patient remained eucalcemic without calcium supplementation.

CONCLUSIONS

Though hypocalcaemia has been described as potential side effect of MKI treatment, this is the first report of a lenvatinib-induced primary hypoparathyroidism, in a patient with a documented normal parathyroid function after surgery. The periodical assessment of calcium-phosphorus metabolism is thus warranted to prevent this potentially lethal side effect, in both post-surgical hypoparathyroid and euparathyroid patients.