Lutetium-177 PRRT for metastatic well-differentiated neuroendocrine tumour.

Patient oncology history.

Failed first-line somatostatin analogue therapy.

Before being considered for Lu-177 PRRT, the patient had been treated with standard first-line systemic therapy for well-differentiated neuroendocrine tumours — injectable Sandostatin-LAR (long-acting octreotide). This is the standard somatostatin analogue used to control symptoms and slow disease progression in NETs.

In the PRRT eligibility assessment, the absence of symptom relief and the documented progression on Sandostatin established the indication for radioligand therapy as the next-line treatment.

Clinical assessment before PRRT.

At the time of presentation for Lu-177 PRRT consideration, the patient's clinical picture comprised:

• Abdominal pain — persistent for 6 months and unresponsive to Sandostatin therapy
• Chromogranin A level of 353 — the primary biochemical marker for neuroendocrine tumour burden (substantially elevated)
• Progressive disease — on prior somatostatin analogue therapy, fulfilling the clinical criterion for second-line PRRT

Pre-therapy Ga-68 DOTANOC PET-CT imaging was performed to confirm somatostatin receptor expression on the tumour (a prerequisite for PRRT eligibility) and to establish a baseline against which treatment response could be measured.

Treatment protocol.

The patient received Lu-177 PRRT following our department's standard PRRT protocol. The protocol specifies the radiopharmaceutical, the dose schedule, the administration route, and the renal protection measures required (the kidneys are the dose-limiting organ in PRRT due to renal radioligand uptake).

Each cycle was preceded by intravenous saline hydration (renal protection protocol) to minimise nephrotoxicity risk from radioligand uptake in the kidneys. Each infusion was well-tolerated with no immediate complications. The patient continued to tolerate the treatment well across all three cycles without any post-infusion complications. The 3-month inter-cycle interval allowed time for assessment of response and recovery of marrow function between doses.

Upon completion of therapy, the patient was discharged in a stable condition with background radiation levels within normal limits — consistent with AERB radiation safety standards for outpatient PRRT.

Chromogranin A response.

The primary biochemical marker for neuroendocrine tumour response — serum Chromogranin A (CgA) — demonstrated a substantial decline over the course of the 3-cycle therapy programme:

The substantial CgA decline reflects significant tumour burden reduction across the metastatic disease. Chromogranin A response is a recognised clinical surrogate for PRRT efficacy, used alongside imaging response to assess treatment outcome. In this patient, the biochemical response correlated with both imaging response and clinical symptom resolution.

Imaging before & after.

Treatment response was assessed with interim and end-of-treatment Ga-68 DOTANOC PET-CT. The interim response scan demonstrated approximately 42% reduction in tumour volume — a substantial morphological response that supported continuation of the therapy course.

The imaging response correlates with the biochemical CgA response — both reflect substantial reduction in tumour burden. Ga-68 DOTANOC is our standard PET tracer for both pre-treatment eligibility (confirming somatostatin receptor expression) and post-treatment response assessment, allowing direct comparison of the same molecular target before and after therapy.

Symptomatic response.

Beyond the biochemical and imaging response, the patient experienced clinically meaningful improvement in his presenting symptoms and overall quality of life:

Upon completion of therapy, the patient was discharged in a stable condition with background radiation levels within normal limits. The combination of symptom relief, biochemical response (CgA decline), and imaging response (42% tumour volume reduction) represents a comprehensive response across all the standard PRRT efficacy endpoints.

What this case illustrates.

This case demonstrates the clinical role of Lu-177 PRRT as second-line therapy in patients with well-differentiated neuroendocrine tumours who have progressed on standard somatostatin analogue therapy. The international guidance for NET treatment positions PRRT as a valuable next-line option in exactly this clinical scenario — somatostatin receptor-positive disease that has demonstrated resistance to somatostatin analogue monotherapy.

Three clinical observations stand out from this case:

• The patient's relatively young age (35 years) and good performance status at the time of PRRT initiation contributed to excellent tolerance of the therapy across all three cycles — consistent with our experience that patients in good baseline condition tolerate radioligand therapy well
• The concordance between biochemical response (CgA 353→132), imaging response (42% volume reduction), and symptomatic response (complete pain relief) reflects a comprehensive treatment effect across all standard efficacy measures — not just a single endpoint
• The 3-month inter-cycle interval allows time for marrow recovery and response assessment between doses, which is our department's standard protocol and aligns with international PRRT delivery practice

This case does not establish a universal outcome — individual response to PRRT varies based on tumour grade, somatostatin receptor expression level, prior treatment, and many other factors. However, it does illustrate that good outcomes can be achieved in patients who have failed first-line somatostatin analogue therapy, and that the team has experience delivering this approach with documented response across biochemical, imaging, and clinical endpoints.

Backed by peer-reviewed research.

Beyond standard intravenous PRRT delivery, Dr. Parul Thakral and our team published peer-reviewed research in the British Journal of Radiology exploring intra-arterial delivery of Lu-177 DOTATATE — a technique that can deliver substantially higher radiation doses to liver-dominant NET metastases while sparing healthy tissue. This pioneering research expands the toolkit available for patients with disease patterns that may benefit from non-standard PRRT delivery:

For patients whose neuroendocrine tumour metastases are concentrated mostly in the liver, intra-arterial Lu-DOTATATE may be considered as an alternative to standard intravenous PRRT at our centre. This option is discussed on a case-by-case basis as part of treatment planning.