Main Session
Sep 27
PQA 01 - Gastrointestinal Cancer and Central Nervous System

2066 - Re-Treatment with 177Lu-edotreotide in Patients with Progressive NETs: A SwissNET Registry Analysis

03:00pm - 04:00pm ET
Poster Hall - Exhibit Hall A
Screen: 27
POSTER

Presenter(s)

Julia Fricke, MD Headshot
Julia Fricke, MD - University Hospital Basel, Basel, Basel-Stad

J. G. Fricke1, G. Nicolas1, A. R. Siebenhüner2, R. M. Kaderli3, J. C. Refardt4, N. Schaefer5, R. Trepp6, S. Pilz7, B. D. Polack8, S. Spiegl9, A. Perren10, and E. Christ11; 1Department of Nuclear Medicine, University Hospital Basel, Basel, Switzerland, 2Clinic for Hematology and Oncology Hirslanden Zürich, Zürich, Switzerland, 3Department of Visceral Surgery and Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland, 4Erasmus University Rotterdam, Rotterdam, Netherlands, 5Lausanne University Hospital, Rue du Bugnon, Switzerland, 6Department of Diabetes, Endocrinology, Nutritional Medicine and Metabolism, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland, 7ITM Oncologics GmbH, Garching/Munich, Germany, 8ITM USA, Inc., Princeton, NJ, 97ITM Oncologics GmbH, Garching/Munich, Germany, 10Institute of Tissue Medicine and Pathology, University of Bern, Bern, Switzerland, 11University Hospital Basel, Endocrinology, Diabetology and Metabolism, ENETS Center of Excellence, Basel, Switzerland

Purpose/Objective(s):

Founded in 2008, the SwissNET registry is a continuous, systematic, prospective data collection from patients diagnosed with NETs in Switzerland who have consented to participation. This is the first study to evaluate the effectiveness of 177Lu-edotreotide in a real-world setting in patients with progressed NETs following initial treatment with 177Lu-edotreotide.

Materials/Methods:

This retrospective study included adults with metastatic, well-differentiated, SSTR-positive NETs who were treated with 177Lu-edotreotide re-treatment (Group A) or with a non-radiopharmaceutical systemic therapy (Group B) post-disease progression =12 months after the initial 177Lu-edotreotide treatment.

177Lu-edotreotide was prepared on-site as a magistral preparation as per Swiss national regulations. The primary endpoint was progression-free survival (PFS), defined as time from start of 177Lu-edotreotide re-treatment or systemic therapy to disease progression (defined as radiological progression [RECIST] or change of treatment modality) or death, whichever occurred first. Secondary endpoints included overall survival from the initial 177Lu-edotreotide treatment until death (OS), objective response rate (ORR; composite radiological, biochemical, and clinical assessment), disease control rate (DCR), and duration of disease control (DDC).

Results:

As of July 2024, 49 patients (mean age: 62.2±13.2 years; female: 53.1%) were included in the study, of which 37 and 12 were in Group A and Group B, respectively.

Primary tumor sites included GI-NET (49.0%), pancreatic NET (30.6%), unknown primary NET (14.3%), lung NET (4.1%) and other NET (2.0%). 34.7%, 55.1%, and 10.2% patients had tumor grades 1, 2 and 3, respectively. 89.6% had liver metastases. Functional NETs were 40.8% and non-functional were 57.1%.

Among patients with available response assessments in Group A (n=34), complete (CR) and partial responses (PR) were observed in 0 and 3 patients, respectively. In Group B (n=6), no patients achieved CR or PR. Median OS was 76 months in patients with functional NETs and not estimable (NE) in those with non-functional tumors in Group A, vs. 36.4 months and NE, respectively in Group B.

Conclusion:

Re-treatment with 177Lu-edotreotide in this small retrospective cohort demonstrated potential for positive efficacy outcomes in patients with progressive NETs after prior 177Lu-edotreotide therapy. Further studies are needed to strengthen the evidence.

Table 1: Treatment Data and Efficacy Results

Data

 Group A

 Group B
Median PFS, months (95% CI)

 12.5 (9.3-19.0)

 4.8 (1.6-8.5)
Median OS, months (95% CI)

 90.1 (71.5-NE)

 39.8 (28.8-NE)
ORR, % (95% CI)

 8.8 (1.9-23.7)

 0.0 (0.0-45.9)
DCR, % (95% CI)

 76.5 (58.8-89.3)

 50.0 (11.8-88.2)
Median DDC, months (95% CI)

 12.0 (6.7-23.6)

 5.2 (3.3-NE)
Median number of 177Lu-edotreotide cycles, weeks (min-max)

 2.0 (1.0-3.0)

Median interval between cycles, weeks (min-max)

 10.0 (5.2-19.9)

Median activity per cycle, GBq (min-max)

 7.3 (4.5-7.5)