Evaluation of switching SSAs on GI-NET progression - experience at an academic medical center

MD Sara Young; MD Matthew Reilley; MD Paul Kunk; MD Muneeb Rehman; Jennifer Hofmann; Le MD PharmD, Tri

doi:10.1530/endoabs.108.C6

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Endocrine Abstracts (2024) 108 C6 | DOI: 10.1530/endoabs.108.C6

NANETS2024 17th Annual Multidisciplinary NET Medical Symposium NANETS 2024 Clinical - Chemo/SSA/Biologics (19 abstracts)

Evaluation of switching SSAs on GI-NET progression – experience at an academic medical center

Sara Young MD , Matthew Reilley MD , Paul Kunk MD , Muneeb Rehman MD , Jennifer Hofmann & PharmD & Tri Le MD

Author affiliations

University of Virginia, VA

Background: Long-acting somatostatin analogs (SSAs), available as lanreotide and octreotide LAR, are the standard of care first-line therapy for metastatic gastrointestinal well-differentiated neuroendocrine tumors (GI-NETs). On initial progression, we have noted a practice of switching patients to the alternate long-acting SSA as second-line therapy. With the availability of several FDA-approved second-line therapies, including PRRT, we sought to evaluate the efficacy of this practice, which is not well supported by available literature.

Methods: Our single-center retrospective study evaluated adult patients with metastatic GI-NETs treated with alternating SSAs on first progression from January 2007 to December 2023. Clinical course and disease characteristics were assessed through chart review. After transitioning to the alternate SSA, disease progression was defined as radiographic evidence of progressive disease or serologic marker increase/clinical symptoms worsening, requiring a change in therapy.

Results: Among 37 patients identified with alternating SSAs, the median age at first SSA initiation was 61.0 years old (IQR 50.0-65.0). SSAs were commonly transitioned due to disease progression (54.1%), medication intolerance (16.2%), symptom control (16.2%), and medication logistical issues, including administration difficulties (13.5%). Although 20 patients progressed, only 19 were available for evaluation due to loss of follow-up. In the 19 patients who transitioned SSAs due to disease progression, all patients were initially on octreotide LAR before transitioning to lanreotide. After transitioning to a second SSA, the median overall survival was 97 days (95% CI, 73-147). Progression was due to imaging progression in 84.2% of patients and serologic/clinical progression in 8.1%.

Table 1. Demographic and clinical characteristics of SSA transitions
	NET Patients (n = 37)
Median age, years (IQR)	61.0 (50.0-65.0)
Male, n (%)	20 (54.1)
Primary site, n (%)
Small bowel	11 (29.7)
Pancreas	5 (13.5)
Colon/Rectum	5 (13.5)
Other/unknown	16 (43.2)
WHO Differentiation, n (%)
Grade 1	7 (18.9)
Grade 2	2 (5.4)
Grade 3	0 (0)
Unknown	28 (75.7)

Conclusions: This real-world cohort demonstrates the limited activity of switching SSAs in patients with progressive disease following first-line treatment with SSAs in the metastatic GI-NET population. This practice has been noted in our region, and we sought to evaluate its efficacy in this limited retrospective study. Switching SSAs on progression is not well supported by previous literature, and with the availability of several FDA-approved second-line therapies, our study does not support its use.

ABSTRACT ID28566