The approval of Amtagvi (lifileucel) in February 2024 for advanced melanoma after PD-1 progression is a landmark that tends to get overshadowed by CAR-T's higher profile. It shouldn't. TIL therapy โ taking tumor-infiltrating lymphocytes from a patient's own tumor, expanding them massively ex vivo, and reinfusing them after lymphodepletion โ works in solid tumors where CAR-T has largely failed. The C-144-01 pivotal trial showed 31.5% overall response rate in patients who had progressed through PD-1 inhibitors โ a population that essentially has no remaining immunotherapy options. The median duration of response was 11.9 months, with 42% of responses ongoing at data cutoff. These are not dramatic numbers by hematologic cancer standards, but in a tumor type defined by resistance to PD-1, they represent real clinical benefit. The question for 2026 is whether TIL therapy can extend beyond melanoma.
This article is for informational purposes only and does not constitute medical advice. TIL and NK cell therapies require specialized treatment centers. Current approvals are limited to specific indications. Consult your oncologist to assess eligibility for available therapies or trials.
Summary
Amtagvi (lifileucel, Iovance Biotherapeutics) is FDA-approved for unresectable or metastatic melanoma after PD-1 and BRAF-targeted therapy (if BRAF V600E+). C-144-01 ORR 31.5%, median DOR 11.9 months. NK cell therapy is in Phase 1/2 using cord blood-derived (FT516, FT538, Fate Therapeutics) and iPSC-derived platforms. The iPSC-derived approach enables genetic engineering of NK cells with enhanced persistence (IL-15 signaling), targeting (CD16 optimization for ADCC), and anti-exhaustion features. TIL therapy is now in trials for NSCLC (IOV-COM-202 โ lifileucel + pembrolizumab), cervical cancer, head and neck, and colorectal cancer. NK cell trials are active in AML, multiple myeloma, and solid tumors. Manufacturing timelines for TIL therapy are 3โ4 weeks; NK cell therapy from iPSC is off-the-shelf.
ClinicalMetric Analysis
- TIL therapy's complete responses, though infrequent, are durable in a way that distinguishes it from chemotherapy in post-PD-1 melanoma. In C-144-01, 4.4% of patients achieved complete response. That sounds modest. But complete responses in melanoma treated with TIL have historically shown remarkable durability โ early NCI data from Steve Rosenberg's group includes patients with CR in excess of 5 years after a single TIL infusion. The biology makes sense: a TIL product contains T cells that have already been educated against the patient's own tumor antigens inside the tumor microenvironment, and a fraction of those T cells become long-lived memory cells. The short-duration partial responses pull down the aggregate durability statistics, but the CRs may be representing a genuinely curative subset.
- NK cell therapy's lack of MHC restriction is a fundamental advantage that hasn't been fully exploited yet because persistence remains the primary limitation. T cells (including TIL and CAR-T) require MHC-peptide matching for target recognition, which is why allogeneic T-cell therapies cause GvHD. NK cells use MHC-independent killing via NKG2D, DNAM-1, and the missing-self mechanism (they preferentially kill cells that downregulate HLA โ a common tumor escape mechanism). This means NK cells can theoretically work off-the-shelf without HLA matching. The clinical limitation is that NK cells expand poorly in vivo and are typically cleared within 2โ4 weeks. iPSC-derived NK cells are now being engineered with IL-15 receptor ฮฒ chain expression (hnCD16, membrane-bound IL-21, CISH knockout) to extend persistence while maintaining anti-tumor activity. FT576, Fate's most advanced iPSC-NK product for myeloma, showed responses at 2+ months post-infusion โ a significant improvement over first-generation NK cell products.
- The biggest unresolved question for TIL expansion to solid tumors is whether surgically inaccessible or poorly infiltrated tumors can yield a functional TIL product. Melanoma is ideally suited for TIL therapy: it is highly immunogenic, frequently resectable with tumor-draining lymph nodes, and generates TIL populations with diverse neoantigen recognition. Tumors like pancreatic cancer, which are desmoplastic, cold, and poorly infiltrated, generate TIL products that are quantitatively and qualitatively inferior. NSCLC is somewhere in between โ immunogenic enough (especially in smokers with high mutational burden) to potentially yield functional TIL products, but with more variable infiltration than melanoma. The IOV-COM-202 trial's early TIL + pembrolizumab data in NSCLC will be informative about whether the melanoma success translates in a different tumor histology.
Amtagvi (Lifileucel): How It Works and What the Trial Showed
The lifileucel manufacturing process begins with surgical resection of a tumor fragment (ideally 1.5โ2 cmยณ of viable tumor). The tumor is enzymatically digested to produce single-cell suspensions; TIL populations are selected and undergo rapid expansion using OKT3 (anti-CD3 antibody) + high-dose IL-2 + irradiated feeder cells. The resulting product contains approximately 7.5 ร 10โน TIL. Before infusion, patients undergo lymphodepletion (cyclophosphamide + fludarabine) to eliminate regulatory T cells and create cytokine "space" for TIL expansion. High-dose IL-2 is administered post-infusion to support TIL persistence.
C-144-01 (NCT02360579): 73 patients with unresectable or metastatic melanoma who had received PD-1 inhibitor and BRAF inhibitor (if BRAF V600E+). ORR 31.5% (23/73 patients). Median DOR 11.9 months (range 1.7+ to 35.2+ months). At data cutoff, 42% of responses ongoing. CR: 3 patients (4.4%). Responses were assessed centrally by irRC criteria. No formal comparison arm (single-arm trial), but historical ORR with current standard of care options post-PD-1 is approximately 5โ15% for available chemotherapy or targeted therapy.
iPSC-Derived NK Cell Platforms: Fate Therapeutics and Beyond
Fate Therapeutics has built the most advanced iPSC-derived NK cell platform. Their process starts with a single iPSC master cell line that is gene-edited with multiple modifications before differentiation into NK cells: CD16 high-affinity Fc receptor (hnCD16) for enhanced ADCC with tumor-directed antibodies; IL-15/IL-15Rฮฑ fusion protein for autocrine cytokine support; CISH knockout to remove a negative regulator of cytokine signaling. The resulting iPSC-NK cells are differentiated in a defined protocol, cryopreserved, and deployed as an off-the-shelf product.
FT516 (targeting AML and NHL with anti-CD20 antibody combinations): Phase 1 data showing ORR of 23% as monotherapy and ~67% with rituximab in R/R NHL โ suggesting the ADCC mechanism works. FT538 (BCMA-targeting for myeloma): Phase 1 data with anti-BCMA antibody combination. FT576 (BCMA-targeting CAR construct added to the iPSC backbone): Phase 1/2 in myeloma, responses at 10+ weeks post-infusion โ meaningfully better persistence than first-generation NK products.
TIL Therapy Expansion Trials in 2026
Iovance Biotherapeutics has the most active TIL expansion program. IOV-COM-202 tests lifileucel in combination with pembrolizumab in NSCLC, head and neck, and bladder cancer โ first-line in some cohorts, post-PD-1 failure in others. Early data (6-month interim) in NSCLC showed ORR 33% in the second-line cohort โ encouraging but requiring larger follow-up. Iovance's cervical cancer program (IOV-SCC-01 and the TILVANCE-301 Phase 3) is in registration-directed trials. Cervical cancer is an interesting TIL target: it is HPV-driven (high neoantigen burden from viral proteins), frequently well-vascularized, and TIL populations enriched for HPV-specific T cells have shown deep responses in early trials.
Immatics (TCR-T cell therapy, distinct from TIL but related) targets MAGE-A4, WT1, and PRAME โ cancer-testis antigens expressed in solid tumors. Their IMA203 product in Phase 2 showed 44% ORR in MAGE-A4-positive advanced solid tumors โ NSCLC, melanoma, synovial sarcoma, head and neck. This bridges TIL and engineered TCR therapy.
Accessing TIL and NK Cell Trials
Amtagvi is available at Iovance-certified treatment centers in the US. Trial enrollment for TIL programs requires pathology-confirmed diagnosis of the eligible tumor type, adequate organ function, prior PD-1 therapy (for most post-PD-1 indications), and surgical feasibility for tumor harvest โ this is a real eligibility constraint that requires a conversation between the patient, oncologist, and surgical team before referral. NK cell trials (Fate Therapeutics, Nkarta, Artiva Biotherapeutics) are at academic medical centers in the US and Europe; most require a hematologic diagnosis (AML, MM, NHL) with standard eligibility criteria. Search ClinicalTrials.gov using terms: "TIL," "tumor infiltrating lymphocyte," "FT516," "FT576," "lifileucel."