Here is a scenario I want you to sit with for a moment.
A 67-year-old man with metastatic castration-resistant prostate cancer. He’s been through enzalutamide and docetaxel. His PSA has been climbing for four months. His most recent CT shows stable bone lesions, nothing new viscerally. He’s ECOG 1. He’s still working part-time. He’s motivated and engaged in his care.
Has he been referred for a PSMA-PET? Has anyone in his care team mentioned 177Lu-PSMA therapy?
In community oncology settings across Appalachia, the answer to both questions is too often no, not because his providers don’t care, but because the referral triggers and eligibility criteria for theranostic therapies haven’t been clearly communicated outside of academic nuclear medicine circles. That patient is sitting in waiting rooms across this corridor right now. Some of them will eventually make it to a theranostics program. Many won’t.
This post is a plain-language walkthrough of who qualifies for the two FDA-approved Lu-177 therapies (Pluvicto (177Lu-PSMA-617) for prostate cancer and Lutathera (177Lu-DOTATATE) for neuroendocrine tumors) written specifically for the oncologists, urologists, and endocrinologists who are making referral decisions in community settings.
I’m not going to reproduce the full prescribing information. I’m going to tell you what the threshold actually looks like in clinical practice, what the common misconceptions are, and what the red flags are that should pause a referral rather than block it.
Pluvicto 177Lu-PSMA-617 — Metastatic Castration-Resistant Prostate Cancer
Pluvicto received FDA approval in March 2022 based on the VISION trial, which enrolled patients with PSMA-positive metastatic castration-resistant prostate cancer who had progressed on both ARSI and taxane-based chemotherapy. The data showed significantly prolonged radiographic progression-free survival and overall survival compared to standard of care.
Let’s go through the eligibility picture systematically.
Core inclusion criteria
| Criterion | What this means in practice |
|---|---|
| Metastatic CRPC | Confirmed metastatic disease plus castrate serum testosterone (<50 ng/dL) with evidence of progression despite ADT. Document a recent testosterone level and PSA trend in your referral. |
| Prior ARSI therapy | At least one androgen receptor signaling inhibitor: enzalutamide, apalutamide, darolutamide, or abiraterone. The patient must have progressed on it typically, not simply discontinued due to side effects without evidence of response failure. Document the agent, duration, and reason for stopping. |
| Prior taxane therapy | As of March 28, 2025, lutetium Lu 177 vipivotide tetraxetan (Pluvicto; Novartis Pharmaceuticals Corporation) received FDA label expansion for use in adults with PSMA-positive metastatic castration-resistant prostate cancer after androgen receptor pathway inhibitor therapy when deferral of taxane-based chemotherapy is clinically appropriate. It is still common for our patients to have at least one taxane-based regimen (docetaxel or cabazitaxel), OR documented ineligibility for taxane chemotherapy before starting. |
| PSMA-positive disease | PSMA-PET/CT using 68Ga-PSMA-11 or 18F-DCFPyL (Pylarify) showing at least one PSMA-positive lesion. High and uniform PSMA expression across all sites is ideal. The imaging confirms the therapy has a biological target before committing to treatment. |
| No PSMA-negative lesions | The VISION trial excluded patients with any metastatic lesion that was PSMA-negative on PET. In practice, discuss mixed-expression findings directly with the theranostics team rather than assuming the patient is excluded as many patients with mixed disease scenarios are treated. |
| Adequate organ function | Renal: CrCl ≥30 mL/min. Hematologic: ANC ≥1,500/μL, platelets ≥100,000/μL, Hgb ≥8 g/dL. Hepatic: bilirubin ≤1.5×ULN. Include a current CBC and CMP with your referral. |
| ECOG PS 0–2 | Patients with ECOG 3–4 require careful individualized discussion. The therapy is not well-tolerated in significantly debilitated patients and the risk-benefit profile shifts considerably. |
The misconceptions that hold up referrals
The single most common one I hear: “My patient has already been through chemo — they’ve been through enough.” This gets the eligibility criteria exactly backwards. Prior taxane therapy was an intiial prerequisite, not a reason to stop. The trial enrolled patients precisely because they had already progressed on the standard lines. Most patients still are treated post-chemo and tolerate the treatment well.
The second: “My patient’s PSA is too high / his disease is too advanced.” PSA level is not an exclusion criterion. Extensive metastatic burden is not an exclusion criterion. Organ function and performance status matter; PSA doesn’t have a cutoff. This is also something we see routinely in the clinic: patients with very high PSA values (>500) that excellent response to therapy.
The third: “He’s already on his next agent — it’s too late.” Treatment sequencing is a nuanced discussion that requires the entire treatment team, not a reason to skip the referral entirely. If the patient meets the other criteria, speak with your local treatment facility to discuss any questions about timing.
What to watch for — relative cautions, not hard stops
- Significant pre-existing xerostomia or salivary gland disease. PSMA is expressed on salivary glands and dry mouth is the most common toxicity for that organ. This doesn't exclude the patient from therapy, but is worth flagging and would be something monitored by the treatment team throughout the course of therapy.
- Prior extensive pelvic or spine radiation can affect marrow reserve and may influence dosimetry decisions.
- Active second malignancy should be assessed on a case-by-case basis with theranostics team. Clinically we have had a number of patient with secondary malignancies that were less urgent than the primary metastatic prostate cancer risk. Response of prostate disease to therapy can enable better targeted treatment of the second cancer.
- Severe renal impairment: CrCl below 30 mL/min is a hard stop; 30–50 mL/min will be monitored closely but is not exclusionary.
Lutathera 177Lu-DOTATATE — Somatostatin Receptor-Positive GEP-NETs
Lutathera was approved in January 2018 based on the NETTER-1 trial and has been a standard-of-care option for somatostatin receptor-positive GEP-NETs for several years. If you treat patients with carcinoid syndrome, pancreatic NETs, or other GEP-NETs and you’re not currently thinking about PRRT referral, this section is for you.
The NETTER-2 trial, published in 2024, extended the evidence base to newly diagnosed advanced grade 2–3 GEP-NETs, shifting PRRT earlier in the treatment algorithm than the original NETTER-1 data suggested.
Core inclusion criteria
| Criterion | What this means in practice |
|---|---|
| SSTR-positive disease | Confirmed somatostatin receptor expression on functional imaging (68Ga-DOTATATE, 68Ga-DOTATOC, or 68Ga-DOTATOC PET/CT, or Octreoscan). If your patient has had a positive octreotide scan or DOTATATE-based PET, that’s the eligibility signal. |
| GEP-NET histology | Gastroenteropancreatic neuroendocrine tumor: midgut, hindgut, foregut, pancreatic, or other GI origin. The original NETTER-1 approval was specifically for midgut NETs; subsequent data has extended to other GEP-NET sites. |
| Grade 1–3, well-differentiated | Grade 1 or 2 (Ki-67 <20%) is the established sweet spot. NETTER-2 extended evidence to grade 2–3 (Ki-67 up to 55%). High-grade neuroendocrine carcinomas (Ki-67 >55%, poorly differentiated) are generally not candidates as SSTR expression is typically low and biology is unfavorable. |
| Inoperable or metastatic | Locally unresectable or metastatic. Patients with resectable disease should have surgical options evaluated first; PRRT is not first-line for resectable tumors. |
| Progression on or ineligibility for SSA | NETTER-1 required progression on first-line long-acting somatostatin analogues (octreotide LAR or lanreotide). NETTER-2 enrolled patients earlier: SSA-naive patients with high-grade or high-burden disease may now have a pathway. Discuss individual cases with your theranostics team. |
| Adequate organ function | Renal: CrCl ≥40 mL/min (note: higher threshold than Pluvicto due to renal handling of DOTATATE). Hematologic: ANC ≥1,500, platelets ≥100,000, Hgb ≥8 g/dL. Extensive hepatic metastasis burden matters and significant liver replacement can compromise both function and dosimetry but isn't typically fully exclusionary. |
| ECOG PS 0–2 | Same standard as Pluvicto. Patients with poor functional status require individualized assessment. |
A practical point about SSTR imaging
If your patient has carcinoid syndrome or a known or suspected GEP-NET and hasn’t had SSTR imaging, that’s the first step. If they had an Octreoscan years ago, consider whether a DOTA-TATE PET/CT would be more appropriate now. PET/CT has significantly better sensitivity and spatial resolution, and it’s now widely available. The PET result will be what the theranostics team uses to confirm eligibility.
SSTR expression intensity on imaging also matters prognostically for PRRT response. Strong uptake across all sites is the favorable picture. Heterogeneous or low-level uptake warrants a more careful eligibility discussion, but again, is typically not exclusionary.
The misconceptions that hold up referrals
The most common one I hear for NETs: “My patient is stable on octreotide, why would we change anything?” Stability on SSA doesn’t mean PRRT isn’t indicated. NETTER-2 data specifically supports offering PRRT to patients with advanced disease earlier than we previously thought, regardless of SSA response status. Stable doesn’t mean optimal. Clinically, we often see patients perform better when PRRT is used in conjunction with SSA treatments.
The second: “The disease is too indolent, we can watch and wait.” For grade 1 midgut NETs with low burden, watchful waiting can be appropriate. For grade 2 or 3 disease, or for patients with significant symptom burden from carcinoid syndrome, the risk-benefit calculation changes. The referral conversation should be happening with the theranostics team.
The third: “I’m not sure if it’s a GEP-NET or a lung NET, does that matter?” Yes, technically, the original NETTER-1 approval was GEP-NET specific. Bronchopulmonary NETs with SSTR-positive disease have been treated off-label with growing evidence. This is exactly the kind of case to discuss with a nuclear medicine specialist rather than assume is excluded. We have clinically had success with several off-label uses, including SSTR+ neuroblastomas that were not surgically resectable and patients were not candidates for chemotherapy.
The fourth: “My patient was already treated with a 177Lu therapy in the past?” This can make a difference, however, we are routinely re-treating patients whose disease has started to progress following PRRT. As long as the patient tolerated the therapy well and meets the standard inclusion criteria, it is worth having the referral discussion with your local theranostics team.
Side-by-Side: At a Glance
For providers who may refer patients for both therapies, here is a quick reference summary.
| Pluvicto (177Lu-PSMA-617) | Lutathera (177Lu-DOTATATE) | |
|---|---|---|
| Indication | mCRPC | GEP-NETs (SSTR+) |
| Key diagnostic | PSMA-PET/CT | DOTA-TATE PET/CT or Octreoscan |
| Prior therapy | ARPI + taxane (or taxane-ineligible) or ARPI and taxane can be delayed | Progression on SSA (or high-grade/high-burden per NETTER-2) |
| Renal threshold | CrCl ≥30 mL/min | CrCl ≥40 mL/min |
| Performance status | ECOG 0–2 | ECOG 0–2 |
| Grade restriction | N/A | Well-differentiated grades 1–3 (Ki-67 <55%) |
| Approval year | 2022 | 2018 |
| Key trials | VISION / PSMA-FORE | NETTER-1 / NETTER-2 |
When to Pull the Trigger on a Referral
The eligibility criteria above are the formal framework. In practice the referral decision often comes down to a simpler question: has this patient progressed past the standard lines and do we have evidence of target expression?
For prostate cancer: if the patient has been through at least one ARPI and at least one taxane (or is taxane-ineligible or taxane can be delayed), has rising PSA or radiographic progression, and is functional enough to tolerate a multi-cycle outpatient treatment, order the PSMA-PET/CT if not already done and place the referral. The theranostics team will handle the detailed eligibility review and discuss with your team.
For NETs: if the patient has SSTR-positive imaging, progressive or symptomatic disease on SSA, and grade 1–2 (or grade 3 well-differentiated) histology, the referral conversation should happen. NETTER-2 data means that waiting for overt progression is no longer the default posture for high-burden or higher-grade disease.
What to include in your referral
- Diagnosis, staging, and current disease status
- Full treatment history with dates, agents, and reason for discontinuation
- Most recent relevant imaging: PSMA-PET for prostate; SSTR PET or Octreoscan for NET (direct DICOM access preferred; report alone is the minimum and typically acceptable)
- Current labs: CBC, CMP, creatinine clearance, testosterone (prostate), and PT-INR for PRRT patients
- PSA trend (prostate) or chromogranin A / 5-HIAA trend (NET) over 3–6 months
- Performance status and relevant comorbidities
- Your clinical question of: “Is this patient a candidate for Lu-177 therapy?” is typically sufficient to start the consultation with your local theranostics team.
Referring Provider’s Quick-Reference: Lu-177 Eligibility Criteria
A one-page at-a-glance reference covering inclusion and exclusion criteria for both Pluvicto and Lutathera — formatted for your clinic or referral folder.
Download the one-pagerARC’s regional workshops include dedicated sessions on theranostics eligibility and the referral pathway, designed specifically for community-based oncologists, urologists, and endocrinologists. If you want to work through cases like the one at the top of this post with nuclear medicine specialists in the room, that’s what we’re building. Workshop details at arctheranostics.org.
Have you had a patient recently who you think may have been a theranostics candidate but didn’t get referred? What stopped the conversation — imaging access, the referral pathway, or something else?
About ARC: The Appalachian Radiotheranostics Coalition is a regional education initiative funded through an SNMMI Mars Shot grant, focused on expanding theranostics access across the Knoxville-to-Roanoke corridor. arctheranostics.org
Key references: VISION trial (Sartor et al., NEJM 2021); NETTER-1 trial (Strosberg et al., NEJM 2017); NETTER-2 trial (Singh et al., The Lancet 2024); Fizazi et al., Lancet Oncol 2023. This post is for educational purposes only and does not constitute medical advice. Verify current FDA-approved prescribing information before clinical application.
