Knowledge Hub · ¹⁷⁷Lu-FAPI
Pancreatic adenocarcinoma, soft-tissue sarcoma, FAP-positive epithelial cancers — these tumour types fall outside the SSTR2 and PSMA targeting landscape, and they are exactly the cancers with the densest stromal FAP expression. ¹⁷⁷Lu-FAPI is investigational, not a regulator-approved SoC, but the published pilot data, the dose-escalation studies and the upstream Lu-177 supply chain are all in place. This page walks what the evidence actually supports today.
Investigational use only
¹⁷⁷Lu-FAPI is not currently an FDA / EMA / CDSCO-approved standard-of-care indication. Clinical use in India requires hospital ethics committee approval and CDSCO investigational-use coverage. The content below summarises peer-reviewed evidence; treat it as evidence background for trial or research programmes, not as a treatment recommendation.
Why this matters
FAP biology
Fibroblast activation protein α (FAPα) is a serine protease expressed on cancer-associated fibroblasts (CAFs) — the stromal scaffolding around carcinomas. FAP is low or absent on most normal adult tissues, making it a relatively clean radionuclide-therapy target. Critically, FAP is expressed in tumours that lack SSTR2 (NET marker) and PSMA (prostate marker) — pancreatic, sarcoma, breast, head-and-neck — opening theranostic reach where DOTATATE and PSMA-617 see nothing.
Based on: Loktev A et al. A tumor-imaging method targeting cancer-associated fibroblasts. J Nucl Med 2018; 59:1423-1429.
Read source ↗FAPI variants
First-generation FAPI-04 (Heidelberg, 2018) had a short tumour-residence half-life — good for diagnostic PET, marginal for therapy. FAPI-46 added a longer-circulating linker, improving tumour dose by ~2-3× per cycle. Newer variants (FAP-2286 dimer, ⁹⁹ᵐTc-FAPI-46, peptide-conjugates) further extend residence time. ¹⁷⁷Lu-FAPI therapy today is almost entirely FAPI-46 or FAPI-04; FAP-2286 is in dose-finding.
Based on: Kratochwil C et al. ⁶⁸Ga-FAPI PET/CT: tracer uptake in 28 different kinds of cancer. J Nucl Med 2019; 60:801-805.
Read source ↗Pancreatic adenocarcinoma
Pancreatic ductal adenocarcinoma (PDAC) carries some of the densest FAP-positive stromal content of any solid tumour. The 5-year survival for advanced PDAC remains around 3 %. Early ¹⁷⁷Lu-FAPI cohorts have reported symptomatic improvement and biochemical response in pre-treated PDAC; cohort sizes are still small and median follow-up short. The clinical rationale — a stroma-directed therapy in a stroma-defined cancer — is strong; the evidence is early-phase, not registration-grade.
Based on: Kuyumcu S et al. Pilot ¹⁷⁷Lu-FAPI therapy in advanced cancers. Eur J Nucl Med Mol Imaging 2021; 48:1605-1612.
Read source ↗Soft-tissue sarcoma
Soft-tissue sarcomas display variable FAP expression on Ga-68 FAPI PET. Subgroups (liposarcoma, leiomyosarcoma, advanced GIST after imatinib failure) show high uptake. ¹⁷⁷Lu-FAPI dose-escalation studies report symptomatic responses in heavily pre-treated sarcoma patients, positioning the therapy as a stroma-directed option after standard chemotherapy lines exhaust.
Based on: Fendler WP et al. Safety and efficacy of ¹⁷⁷Lu-FAPI-46 radioligand therapy in patients with advanced sarcoma. J Nucl Med 2022.
Read source ↗Dosimetry profile
Compared to DOTATATE (~14-day tumour residence) and PSMA-617 (~2-day residence), FAPI peptides have substantially shorter tumour retention. The dose-escalation strategy compensates with higher activity per cycle, shorter cycle intervals, and pairing with linker chemistries that extend residence. Kidney is the dominant organ at risk; bone-marrow dose is generally well below cytopenia thresholds at current dose-finding activity levels.
Based on: Watabe T et al. Dosimetry of ¹⁷⁷Lu-FAPI-46 in patients with metastatic cancer. Eur J Nucl Med Mol Imaging 2023.
Read source ↗Indian regulatory framing
In India, ¹⁷⁷Lu-FAPI is not a routine clinical option. Use requires hospital ethics committee approval, CDSCO investigational-use coverage (Form CT-04 for clinical trials or institutional ethics-committee compassionate-use letter), AERB import licensing on the Lu-177 supply, and patient-level informed consent appropriate for off-protocol or research use. Saxsons supplies the radionuclide leg; the centre owns the ethics and CDSCO paperwork.
Based on: AERB Atomic Energy (Radiation Protection) Rules 2004; CDSCO New Drugs and Clinical Trials Rules 2019.
Read source ↗The Heidelberg foundational papers, FAPI-46 dose-finding studies, and the CDSCO + AERB framework for Indian investigational use.
Foundational paper introducing FAPI tracer chemistry from the Heidelberg group.
Pan-tumour Ga-68 FAPI PET uptake survey establishing the FAP-positive cancer landscape.
Early efficacy and safety of ¹⁷⁷Lu-FAPI-46 in advanced sarcoma cohorts.
Tumour and organ-at-risk dosimetry of ¹⁷⁷Lu-FAPI-46 in metastatic cancer cohorts.
Indian regulatory framework for investigational radiopharmaceutical use.