Cinacalcet for hypercalcemia caused by pulmonary squamous cell carcinoma producing parathyroid hormone-related Peptide

Cinacalcet increases renal calcium excretion in PTHrP-mediated hypercalcemia: a case report

BACKGROUND

In the acute setting, PTH-independent hypercalcemia is typically treated with anti-resorptive agents such as zoledronic acid or denosumab. When these agents are no longer able to control hypercalcemia, several case reports have shown the utility of cinacalcet. However, it is not known if cinacalcet can be effective in patients naïve to anti-resorptive therapy or how cinacalcet ameliorates the hypercalcemia.

CASE PRESENTATION

A 47-year-old male with a history of alcohol-induced cirrhosis was admitted for left cheek bleeding and swelling from an infiltrative squamous cell carcinoma of the oral cavity. On admission, he was found to have an elevated albumin-corrected serum calcium of 13.6 mg/dL, a serum phosphorus of 2.2 mg/dL and an intact PTH of 6 pg/mL (normal 18-90) with a PTHrP of 8.1 pmol/L (normal < 4.3), consistent with PTHrP-dependent hypercalcemia. Aggressive intravenous saline hydration and subcutaneous salmon calcitonin were initiated, but his serum calcium remained elevated. Given tooth extractions scheduled for the next day and possible irradiation to the jaw in the near future, alternatives to antiresorptive therapy were sought. Cinacalcet was initiated at 30 mg twice daily then increased to 60 mg twice daily the following day. The albumin-corrected serum calcium level decreased from 13.2 to 10.9 mg/dL within 48 h. The fractional excretion of calcium increased from 3.7 to 7.0%.

CONCLUSIONS

This case demonstrates the utility of cinacalcet for the treatment of PTHrP-mediated hypercalcemia without prior anti-resorptive therapy via increased renal clearance of calcium.

Refractory paraneoplastic hypercalcaemia responding to cinacalcet

A woman in her late 70s presented with an increased frequency of micturition, suprapubic pain and weight loss. She was found to be having advanced cancer of the urinary bladder, coupled with bilateral hydronephrosis.Whilst undergoing surgical intervention for the latter, she was incidentally found to be having hypercalcaemia. This was found to be paraneoplastic in nature, possibly due to elevated parathyroid hormone related peptide with no evidence of bone metastasis. The histology of the resected tumour revealed squamous and sarcomatoid differentiation. Her hypercalcaemia initially responded to intravenous fluids, and later on zolendronate,but the problem recurred again, with the response to a repeat dose of zolendronate and even denosumab being unsatisfactory. As a last resort cinacalcet was started, and although there was a good response to it, our patient sadly died a few weeks later.We believe our case to be the first case of hypercalcaemia associated with isolated bladder cancer which showed a successful response to cinacalcet.

Hypercalcemia: A Review

IMPORTANCE

Hypercalcemia affects approximately 1% of the worldwide population. Mild hypercalcemia, defined as total calcium of less than 12 mg/dL (<3 mmol/L) or ionized calcium of 5.6 to 8.0 mg/dL (1.4-2 mmol/L), is usually asymptomatic but may be associated with constitutional symptoms such as fatigue and constipation in approximately 20% of people. Hypercalcemia that is severe, defined as total calcium of 14 mg/dL or greater (>3.5 mmol/L) or ionized calcium of 10 mg/dL or greater (≥2.5 mmol/L) or that develops rapidly over days to weeks, can cause nausea, vomiting, dehydration, confusion, somnolence, and coma.

OBSERVATIONS

Approximately 90% of people with hypercalcemia have primary hyperparathyroidism (PHPT) or malignancy. Additional causes of hypercalcemia include granulomatous disease such as sarcoidosis, endocrinopathies such as thyroid disease, immobilization, genetic disorders, and medications such as thiazide diuretics and supplements such as calcium, vitamin D, or vitamin A. Hypercalcemia has been associated with sodium-glucose cotransporter 2 protein inhibitors, immune checkpoint inhibitors, denosumab discontinuation, SARS-CoV-2, ketogenic diets, and extreme exercise, but these account for less than 1% of causes. Serum intact parathyroid hormone (PTH), the most important initial test to evaluate hypercalcemia, distinguishes PTH-dependent from PTH-independent causes. In a patient with hypercalcemia, an elevated or normal PTH concentration is consistent with PHPT, while a suppressed PTH level (<20 pg/mL depending on assay) indicates another cause. Mild hypercalcemia usually does not need acute intervention. If due to PHPT, parathyroidectomy may be considered depending on age, serum calcium level, and kidney or skeletal involvement. In patients older than 50 years with serum calcium levels less than 1 mg above the upper normal limit and no evidence of skeletal or kidney disease, observation may be appropriate. Initial therapy of symptomatic or severe hypercalcemia consists of hydration and intravenous bisphosphonates, such as zoledronic acid or pamidronate. In patients with kidney failure, denosumab and dialysis may be indicated. Glucocorticoids may be used as primary treatment when hypercalcemia is due to excessive intestinal calcium absorption (vitamin D intoxication, granulomatous disorders, some lymphomas). Treatment reduces serum calcium and improves symptoms, at least transiently. The underlying cause of hypercalcemia should be identified and treated. The prognosis for asymptomatic PHPT is excellent with either medical or surgical management. Hypercalcemia of malignancy is associated with poor survival.

CONCLUSIONS AND RELEVANCE

Mild hypercalcemia is typically asymptomatic, while severe hypercalcemia is associated with nausea, vomiting, dehydration, confusion, somnolence, and coma. Asymptomatic hypercalcemia due to primary hyperparathyroidism is managed with parathyroidectomy or observation with monitoring, while severe hypercalcemia is typically treated with hydration and intravenous bisphosphonates.

Treatment of malignancy-associated hypercalcemia with cinacalcet: a paradigm shift

Palliation of symptoms related to malignancy-associated hypercalcemia (MAH) is essential and clinically meaningful for patients, given the continued poor prognosis, with high morbidity and mortality associated with this disease process. Historically, agents have been temporizing, having no impact on patient morbidity nor survival. We suggest that cinacalcet can be an efficacious agent to be taken orally, reducing patients' time in the hospital/clinic settings. It is well-tolerated and maintains serum calcium levels in the normal range, while targeted cancer treatments can be employed. This has a direct, major impact on morbidity. Maintaining eucalcemia can increase quality of life, while allowing targeted therapies time to improve survival. Given that our case (and others) showed calcium reduction in MAH, there is promising evidence that cinacalcet can be more widely employed in this setting. Future consideration should be given to studies addressing the efficacy of cinacalcet in calcium normalization, improvement of quality of life, and impact on survival in patients with MAH. Though the exact mechanism of action for cinacalcet's reduction in calcium in this setting is not currently known, we can still afford patients the possible benefit from it.

Cinacalcet for the Treatment of Humoral Hypercalcemia of Malignancy: An Introductory Case Report with a Pathophysiologic and Therapeutic Review

Hypercalcemia is an ominous development in the course of malignancy associated with a mean survival of only several months. A majority of cases of hypercalcemia are related to humoral hypercalcemia of malignancy (HHM), where hypercalcemia is caused by increased levels of circulating parathyroid hormone-related protein (PTHrP). Mainstay treatments in the management of HHM are intravenous fluids, intravenous bisphosphonates, and subcutaneous denosumab, although hypercalcemia oftentimes recurs despite these efforts. We present a case of advanced non-small cell lung cancer with PTHrP-mediated hypercalcemia that proved resistant to standard therapy. A trial of oral cinacalcet was initiated and improved calcium levels for 2 months despite a progressive rise in PTHrP and prior to subsequent disease progression. Based on the current body of literature, we propose that this calcium-lowering effect of cinacalcet occurs due to a potential effect on renal calcium excretion.

Malignant melanoma with indiscoverable skin manifestations presenting with paresis and refractory hypercalcemia: A case report

RATIONALE

Malignant melanoma with indiscoverable skin manifestations is unusual and refractory hypercalcemia with high metabolic signal of the rectum as initial manifestation is very rare.

PATIENT CONCERNS

We present a case that presented with paresis, nausea, and vomiting.

DIAGNOSES

Malignant melanoma with spinal metastasis.

INTERVENTIONS AND OUTCOMES

The patient underwent posterior decompression, partial tumor resection, bone cement reconstruction, and internal fixation. The patient's hypercalcemia was controlled and muscle strength was partially recovered. The immunohistochemical stainings showed Melan-A (+), HMB45 (+), s-100 (+), Vimentin (+), and AE1/AE3 (-).

LESSONS

We emphasize the necessity of screening potential existence of neoplasms for the patients with hypercalcemia. Surgical treatment is still necessary for patients with spinal metastasis.

Supportive therapy in gastroenteropancreatic neuroendocrine tumors: Often forgotten but important

Neuroendocrine tumors (NETs) are a group of rare and heterogeneous malignancies that can develop in various organs. A significant number of gastroenteropancreatic neuroendocrine tumours (GEP-NETs) is functionally active and presents with symptoms related to the secretion of biologically active substances, leading to the development of distinct clinical syndromes. There are various therapeutic approaches for GEP-NETs, including curative surgery, palliative surgery, local-ablative and loco-regional therapies as well as systemic therapeutic options including peptide receptor radionuclide therapy, cytotoxic therapy, and molecularly targeted therapies. Specific supportive therapy of patients with NETs includes management or prevention of hormone-related clinical syndromes and paraneoplastic states. Supportive therapy plays a key role in NET treatment. Supportive therapy includes debulking surgery and interventional radiologic techniques to reduce tumour bulk or load, as well as systemic medical treatment options to manage or prevent hypersecretion syndromes and treatment-related side effects. Supportive therapies are a type of of comprehensive treatment addressing the patient as a whole person throughout the process of NET treatment. Therefore, supportive therapy also encompasses psychosocial support, expert nursing, nutritional support and management of cancer related pain.

Use of cinacalcet and sunitinib to treat hypercalcaemia due to a pancreatic neuroendocrine tumor

Neuroendocrine tumors (NETs) can secrete hormones, including ectopic secretions, but they have been rarely associated with malignant hypercalcemia. A 52-year-old man with a history of diabetes mellitus was diagnosed with a pancreatic tumor. A pancreatic biopsy confirmed a well-differentiated pancreatic NET (pNET). The patient subsequently developed liver metastasis and hypercalcemia with high 1,25 OH vitamin D and suppressed parathyroid hormone (PTH) levels. Hypercalcemia was refractory to chemotherapy, intravenous saline fluids, diuretics, calcitonin and zoledronate. Cinacalcet administration (120 mg/day) resulted in a significant calcium reduction. Hypocalcemia was observed when sunitinib was added three months later and cinacalcet was stopped. Subsequently, the calcium and PTH levels normalized. After six months, we observed 20% shrinkage of the pancreatic tumor and necrosis of a liver metastasis. Cinacalcet is an allosteric activator of the calcium receptor agonist, and it is used for severe hypercalcemia in patients with primary (benign and malignant) hyperparathyroidism. In this patient, cinacalcet demonstrated a calcium lowering effect, normalized hypophosphatemia, and improved the clinical condition of the patient. The mechanism through which cinacalcet improved PTH-rp mediated hypercalcemia is still unclear, but studies have suggested that a potential mechanism is the activation of calcitonin secretion. Sunitinib is an oral multi-targeted tyrosine kinase inhibitor used to treat advanced pNETs. The hypocalcemic effects of sunitinib have not been previously described in a patient with pNET. Here, we report for the first time the successful combination of cinacalcet and sunitinib in the treatment of a pNET patient presenting with malignant hypercalcemia.

Denosumab Therapy for Refractory Hypercalcemia Secondary to Squamous Cell Carcinoma of Skin in Epidermolysis Bullosa

Hypercalcemia secondary to malignancy is rare in children and the majority is caused by tumor-produced parathyroid hormone-related protein (PTHrP). We report a case of hypercalcemia refractory to bisphosphonate and corticosteroid therapy, but responsive to denosumab. A 17-year-old boy with epidermolysis bullosa (EB) and advanced squamous cell carcinoma (SCC) of the left leg was referred with severe hypercalcemia (serum calcium, 4.2 mmol/L). The serum parathyroid hormone (PTH) was 0.7 pmol/L (1.1 - 6.9 pmol/L). The hypercalcemia was initially managed with hyperhydration, prednisolone and pamidronate. Following two infusions of pamidronate (1 mg/kg/dose), serum calcium fell to 2.87 mmol/L. However the hypercalcemia relapsed within a week (serum calcium, 3.61 mmol/L) needing aggressive management with intravenous fluids, prednisolone and two further doses of pamidronate. The serum calcium fell to 2.58 mmol/L over the first 4 days, but rose to 3.39 mmol/L 3 days later. As the hypercalcemia was refractory to bisphosphonate treatment, a trial dose of subcutaneous denosumab (60 mg) was administered following which the calcium fell to 2.86 mmol/L within 24 h and normocalcemia was sustained 4 days later. We report a case of refractory hypercalcemia secondary to malignant SCC, which responded well to denosumab therapy. To our knowledge, this is the first case of hypercalcemia of malignancy in an adolescent managed with denosumab.

Cinacalcet attenuates hypercalcemia observed in mice bearing either Rice H-500 Leydig cell or C26-DCT colon tumors

Excessive secretion of parathyroid hormone-related protein (PTHrP) by tumors stimulates bone resorption and increases renal tubular reabsorption of calcium, resulting in hypercalcemia of malignancy. We investigated the ability of cinacalcet, an allosteric modulator of the calcium-sensing receptor, to attenuate hypercalcemia by assessing its effects on blood ionized calcium, serum PTHrP, and calcium-sensing receptor mRNA in mice bearing either Rice H-500 Leydig cell or C26-DCT colon tumors. Cinacalcet effectively decreased hypercalcemia in a dose- and enantiomer-dependent manner; furthermore, cinacalcet normalized phosphorus levels, but did not affect serum PTHrP. Ribonuclease protection assay results demonstrated presence of PTHrP receptor, but not calcium-sensing receptor mRNA in C26-DCT tumors. The mechanism by which cinacalcet lowered serum calcium was investigated in parathyroidectomized rats (i.e., without PTH) made hypercalcemic by PTHrP. Cinacalcet attenuated PTHrP-mediated elevations in blood ionized calcium, which were accompanied by increased plasma calcitonin. Taken together these results suggest that the cinacalcet-mediated decrease in serum calcium is not the result of a direct effect on tumor cells, but rather is the result of increased calcitonin release. In summary, cinacalcet effectively reduced tumor-mediated hypercalcemia and corrected hypophosphatemia in mice. Further investigation of cinacalcet for treatment of hypercalcemia of malignancy is warranted.