Lenvatinib-induced hypocalcaemia due to transient primary hypoparathyroidism

Toceranib phosphate for treatment of hypercalcaemia of malignancy in two dogs with metastatic anal sac apocrine gland adenocarcinoma

CASE HISTORY

Two dogs, a 10-year-old male Siberian Husky cross and an 11-year-old male Cocker Spaniel were referred to a specialist veterinary hospital in Melbourne, Australia, for treatment of metastatic anal sac apocrine gland adenocarcinoma (ASAGAC) and concurrent hypercalcaemia (concentration of ionised calcium in serum > 1.5 mmol/L) of malignancy.

CLINICAL FINDINGS

Case 1 had a left anal sac mass approximately 5.5 cm in diameter, enlarged sub-lumbar lymph nodes palpable on rectal examination and a concentration of ionised calcium in serum of 2.45 (reference range 1.2-1.32) mmol/L. Soft tissue opacities suspicious for metastatic pulmonary nodules were observed on thoracic radiographs. CT of Case 2 revealed bilateral anal gland masses (left: 4.7 × 3.2 cm; right: 2.8 × 2.1 cm) and a large, ill-defined, intrapelvic mass (7.0 × 6.0 cm) encompassing the medial iliac and internal iliac lymph nodes and intimately associated with the aortic blood vessels. Cytology of fine-needle aspirates of the anal gland masses of both dogs was consistent with ASAGAC. The owners of both dogs declined surgical intervention and medical management with toceranib phosphate was initiated in the gross disease setting.

TREATMENT AND OUTCOME

Toceranib was initially administered at a dose of 2.5 mg/kg orally every other day in both dogs. Due to side effects from this medication, including hypocalcaemia, the dosing schedule was adjusted to Monday, Wednesday, and Friday with a dose range of 2.25-2.5 mg/kg. Both dogs remained alive, Case 1 after 519 days and Case 2 after 477 days, and were normocalcaemic at the time of writing. Both dogs experienced resolution of hypercalcaemia of malignancy while being treated with toceranib alone: hypercalcaemia was controlled for a total of 12 months in Case 1 and 15 months in Case 2. During treatment the anal sac mass of Case 1 remained approximately 5 cm in diameter and the sub-lumbar lymph node remained subjectively stable though no objective measurements were taken. Case 2's anal sac masses and intrapelvic lymph node mass subjectively reduced in size based on palpation.

CLINICAL RELEVANCE

This case series highlights two instances where toceranib monotherapy effectively managed hypercalcaemia of malignancy secondary to metastatic ASAGAC. Despite the presence of extensive macroscopic neoplastic disease, both dogs achieved durable control of hypercalcaemia with toceranib treatment.Abbreviations: ASAGAC: Anal sac apocrine gland adenocarcinoma; cRECIST: Canine response evaluation criteria in solid tumours; HHM: Humoral hypercalcaemia of malignancy; OST: Overall survival time; PFS: Progression-free survival; PTH: Parathyroid hormone; PTHrP: Parathyroid-related hormone peptide; RTK: Receptor tyrosine kinase; TKI: Tyrosine kinase inhibitor.

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.