Cost effectiveness of tyrosine kinase inhibitor therapy in metastatic gastrointestinal stromal tumors

KIT exon 11 and PDGFRA exon 18 gene mutations in gastric GIST: proposal of a short panel for predicting therapeutic response

Background

GIST is the most common mesenchymal tumor of gastrointestinal tract and is more frequent in stomach. Its main mutations affect KIT and PDGFRA genes. Full genetic analysis panels are currently used to study mutations in GIST and other tumors. Considering that in gastric GIST KIT gene mutations in exon 11 are sensitive to IM whereas PDGFRΑ gene mutations in exon 18 (D842V) are resistant to the same drug, the aim of this study is to focus on these two molecular targets as a short alternative panel for predicting therapeutic response in gastric GIST which might optimize resources.

Methods

The genotypes of 38 cases of primary GIST were determined by performing bidirectional DNA sequencing.

Results

Exon 11 of KIT gene showed mutations in 65.3% and the exon 18 of PDGFRA gene showed 9% of cases. So it was possible to determine a subgroup of tumors which presented mutations in KIT exon 11 and PDGFRA exon 18.

Conclusion

Considering all of the foregoing analyzed globally, the application of short panel has impact on the cost and time of release of results to the physician, allowing a rapid approach to patients eligible for treatment with the target therapy.

The economic impact of cytoreductive surgery and tyrosine kinase inhibitor therapy in the treatment of advanced gastrointestinal stromal tumours: a Markov chain decision analysis

PURPOSE

The current first-line treatment for patients with recurrent or metastatic gastrointestinal stromal tumours (GIST) is management with tyrosine kinase inhibition (TKI). There is an undefined role for surgery in the management of these patients. This study uses a cost analysis to examine the economic impact of treating patients with TKI in combination with surgery at different time-points in their treatment trajectories.

METHODS

A Markov chain decision analysis was modelled over a 2-year time horizon to determine costs associated with surgery in combination with imatinib mesylate (IM) or sunitinib malate (SU) in seven scenarios varied by TKI agent, dose and disease status (stable versus localised progressive disease). Rates of disease progression, surgical morbidity, mortality and adverse drug reactions were extracted from the existing literature. Deterministic sensitivity analyses were performed to examine changes in cost due to variations in key variables.

RESULTS

The least-costly scenario was to perform no surgery. The most costly scenario was to perform surgery on patients with localised progressive disease on IM 800 mg. The overall range of costs clustered within approximately $47,000 (USD). Variations in surgical cost, surgical mortality and cost of IM demonstrated thresholds for changing the least-costly scenario within plausible tested ranges.

CONCLUSION

Costs of surgical intervention at different time-points within the treatment course of patients with advanced GIST fluctuate within a relatively narrow range, suggesting that costs arise primarily from the administration of TKI. The decision to pursue cytoreductive surgery should not be based on cost alone. Future studies should incorporate health-state utilities when available.

Efficacy and economic value of adjuvant imatinib for gastrointestinal stromal tumors

OBJECTIVE

This article presents the clinical effectiveness and cost-effectiveness of the use of adjuvant imatinib mesylate for treating patients with localized primary gastrointestinal stromal tumors (GISTs) and discusses the impact of prolonged treatment with adjuvant imatinib on health care costs.

METHODS

A systematic review of the medical literature was conducted to explore recently reported clinical trials demonstrating the clinical benefit of adjuvant imatinib in GISTs, along with analyses discussing the economic impact of adjuvant imatinib.

RESULTS

Two phase III trials have demonstrated a significant clinical benefit of adjuvant imatinib treatment in GIST patients at risk of recurrence after tumor resection. Guidelines now suggest adjuvant treatment for at least 3 years in patients at high risk of recurrence. Despite this clinical effectiveness, prolonged use of adjuvant imatinib can lead to an increase in the risk for adverse events and to increased costs for both patients and health care systems. However, the increased cost is partially offset by cost reductions associated with delayed or avoided GIST recurrences. Three years of adjuvant treatment in high-risk patients was concluded to be cost-effective. Therefore, the careful selection of patients who are most likely to benefit from treatment can lead to improved clinical outcomes and significant cost savings.

CONCLUSION

Although introducing adjuvant imatinib has an economic impact on health plans, this effect seems to be limited. Several analyses have demonstrated that adjuvant imatinib is more cost-effective for treating localized primary GISTs than surgery alone. In addition, 3 years of adjuvant imatinib is more cost-effective than 1 year of adjuvant therapy.

Vandetanib for the treatment of metastatic medullary thyroid cancer

Medullary thyroid cancer (MTC) represents an aggressive form of thyroid malignancy. Some may occur spontaneously or can be associated with Multiple Endocrine Neoplasia syndromes, or Familial Medullary Thyroid Cancer syndrome. In these patients, the protooncogene RET (rearranged during transfection) is mutated. In patients who have unresectable or metastatic disease, the long term prognosis is poor. New treatments for this disease have focused on the use of targeted agents that inhibit the receptor tyrosine kinase of RET. One of these treatments, Vandetanib (Caprelsa, Astra Zeneca), recently has received approval from the Food and Drug Administration for the treatment of patients with progressive locally advanced and/or metastatic disease. This review highlights the studies that led to the drug's approval, and discusses on the potential financial costs of treatment and side effects of this therapy. The main clinical studies evaluating Vandetanib for the treatment of other solid tumors will also be reviewed.