ECE2021 Audio Eposter Presentations Pituitary and Neuroendocrinology (113 abstracts)
1Aberdeen Royal Infirmary, Department of Endocrinology, Aberdeen, United Kingdom; 2WelcomeMRC Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge Endocrine Molecular Imaging Group, Cambridge, United Kingdom
Background/methods
Patients with uncontrolled acromegaly or receiving high cost medical therapy despite initial treatment, usually transsphenoidal surgery (TSS), were considered for a ¹¹C-methionine PET-CT scan (11C-Met PET-CT). This imaging technique may identify a target for TSS or radiotherapy when MRI appearances are inconclusive1. In preparation, four patients on long-term SSA were taken off treatment 3 months prior to the scan. Due to issues with the cyclotron, 2 scans had to be deferred (increasing the duration of the treatment pause). We reintroduced SSA therapy in all 4 patients and noticed an improvement in biochemical response.
Results
Patient | 1 | 2 | 3 | 4 |
Primary therapy | Medical | TSS | TSS | TSS |
Treatment prior to 11C-Met PET-CT | Octreotide LAR 20 mg 6-weekly |
Octreotide LAR 10mg 4-weekly |
Lanreotide ATG 120 mg 4-weekly |
Lanreotide ATG 120 mg 4-weekly |
IGF1ΧULN¥ at diagnosis (year) | 1.8 (1999) | 6.1 (2011) | 4.6 (2012) | 2.1 (1994) |
Duration of SSA treatment (years) | 18 | 1 | 4 | 23 |
IGF1ΧULN¥ at treatment pause | 1.07 | 1.14 | 0.78 | 1.41 |
Duration of treatment pause (months) |
8 | 6 | 4 | 8 |
IGF1ΧULN¥ prior to treatment restart | 1.5 | 1.13 | 1.0 | 1.33 |
Duration of treatment post SSA restart (years) | 3 | 2 | 3 | 3 |
Latest IGF1ΧULN¥ | 0.87 | 0.98 | 1.06* | 0.8 |
11C-Met PET-CT outcome | Awaiting Surgery | Deferred | No surgical target | Deferred |
Current treatment | Octreotide LAR 20 mg 6-weekly |
Octreotide LAR 10 mg 6-weekly |
Lanreotide ATG 120 mg 12 weekly* | Lanreotide ATG 120 mg 4-weekly |
¥ Upper limit of normal; * Dose frequency increased from 12 weekly to 10 weekly (patient living abroad and had requested reduced dosing frequency)
Discussion
Tachyphylaxis is defined as a diminishing response to successive doses of a medication, rendering it less effective. SSA therapy is not anticipated to demonstrate tachyphylaxis in acromegaly2, although there has been one report of partial tachyphylaxis3. Our four patients appear to have experienced a resensitisation to SSA therapy following a short treatment pause as evidenced by improved biochemical control; despite two of them having a reduced dosing frequency. The possibility of a treatment pause improving the sensitivity and biochemical control following reintroduction of SSA therapy has been reported in polycystic liver disease4.
References
1. Koulouri O et al. European Journal of Endocrinology (2016).
2. Lamberts SWJ et al. European Journal of Endocrinology (2019).
3. Wahid ST et al, European Journal of Endocrinology (2002).
4. René M et al, Therapeutic Advances in Gastroenterology (2018).