SITC 2026: 5 Immuno-Oncology Abstracts That Move Stocks

Every biotech investor knows ASCO moves stocks. Fewer screen SITC, the Society for Immunotherapy of Cancer’s annual meeting, and that is the edge. SITC 2026 runs November 4-8 in Phoenix. The trade fires before the podium: regular abstracts lift their embargo November 3 at 9 a.m. Eastern, and late-breakers go live November 6. If you wait for the presenter to step up, the stock has already gapped. This is the middle bookend of the site’s conference franchise, sitting between the ESMO 2026 preview and the ASH 2026 preview.

SITC is where solid-tumor immuno-oncology lands that does not fit ASCO, ESMO, or ASH: TIL therapy, TCR engagers, cancer vaccines, and bispecific ADCs. Here are five names where one dataset re-rates the thesis, ranked by stock-moving potential.

1. Summit Therapeutics ivonescimab: The PDUFA That SITC Sets Up

Summit Therapeutics closed at $15.61, a $12.45 billion market cap. Its ivonescimab, a PD-1/VEGF bispecific, carries a PDUFA goal date of November 14 for EGFR-mutated non-small cell lung cancer after a third-generation EGFR TKI, based on the global Phase 3 HARMONi trial. That date is ten days after SITC closes, which makes SITC the setup, not the trade. The BLA rests on the HARMONi progression-free survival result, with updated overall survival at the June 2026 cut showing a hazard ratio of 0.76 (95% CI 0.61-0.95, nominal p=0.0151) versus placebo plus chemo. The China-region HARMONi-2 monotherapy trial showed a median OS of 30.8 months versus 22.6 for Keytruda (HR 0.73, p=0.009).

The abstract to screen for is any HARMONi follow-up or new-indication data that firms up the OS case heading into the PDUFA. A $12.45 billion market cap already prices a lot of the approval, so the re-rate is less about the decision itself and more about any signal that ivonescimab’s benefit extends beyond the EGFR-mutant population. The risk is the reverse: an AdCom-style negative surprise would unwind a richly priced name. The ivonescimab HARMONi-2 OS data and the November PDUFA setup are covered.

2. Iovance Amtagvi: The TIL Category Leader With an Expansion Catalyst

Iovance Biotherapeutics closed at $11.00, a $4.98 billion market cap. Amtagvi (lifileucel) is the only FDA-approved TIL therapy, and the commercial engine is finally spinning: record second-quarter revenue of about $99 million total with Amtagvi at $91 million, up 66% year over year, on full-year guidance of $350-370 million. SITC is the natural venue for the expansion data, specifically lifileucel in non-small cell lung cancer (IOV-LUN-202), endometrial cancer, and the next-generation IL-12 tethered TIL IOV-5001.

The re-rate thesis is that TIL works beyond melanoma. Melanoma is a 10,000 to 12,000 patient annual US market; a lung label would roughly triple the addressable population. If SITC shows lifileucel’s lung or endometrial data trending toward the melanoma response rates, Iovance re-rates from a single-indication story to a platform. The TILVANCE-301 Phase 3 trial in frontline melanoma is the confirmatory path to full approval, and the next-generation IL-12 tethered TIL and IL-2 analog programs are the shots on goal that make this a platform rather than a one-drug story. The risk is that TIL manufacturing still caps the ramp, and a $4.98 billion market cap already prices solid execution. The record Amtagvi quarter and the cell therapy beyond CAR-T framework are covered.

3. Moderna intismeran: The Cancer Vaccine Platform’s Next Data Point

Moderna closed at $198.88, a $79.4 billion market cap, and it is the pure-play read on the mRNA cancer vaccine thesis. Its intismeran (mRNA-4157) plus Keytruda met the primary endpoint of recurrence-free survival and the key secondary endpoint of distant metastasis-free survival in the Phase 3 INTerpath-001 trial in resected stage IIB-IV melanoma, announced August 19. Merck and Moderna called the improvements statistically significant and clinically meaningful over Keytruda alone, but have not disclosed the hazard ratios or p-values; those come at an upcoming medical meeting. This is the first positive Phase 3 for an individualized neoantigen therapy, and the first for an mRNA-based cancer treatment, which is why the read matters beyond the single indication. The Phase 2b five-year data showed an RFS hazard ratio of 0.51 and a DMFS hazard ratio of 0.411, and the full Phase 3 readout is covered.

SITC is where any extension of that platform gets its first public read, whether that is longer follow-up, a new tumor type, or the manufacturing economics of a personalized vaccine. The honest framing: Moderna at $79.4 billion is near the mega-cap line, and the stock already absorbed the INTerpath-001 win in August. The trade here is the platform thesis, not the daily tick. The intismeran landmark data is covered.

4. Immatics: The PRAME TCR-T and Engager Dark Horse

Immatics closed at $8.37, a $1.27 billion market cap, and it is the one name here with two distinct SITC slots. The company’s PRAME-directed TCR-T (IMA203, IMA203CD8) has shown durable responses in melanoma and sarcoma, and its TCR-based bispecific engagers, IMA401 targeting MAGE-A4/A8 and IMA402 targeting PRAME, are the next wave. IMA401’s first-in-human data across 61 advanced solid tumor patients is published in Nature Medicine with a 29% confirmed response rate (4 of 14) and 64% disease control rate in head and neck cancer, plus responses in melanoma and squamous NSCLC.

The re-rate thesis is that SITC is the venue where PRAME TCR-T and TCER data meet the checkpoint-refractory reality. PRAME is expressed across a wide range of solid tumors, and a bispecific that hits it without the toxicity of a full T-cell transplant is a differentiated bet. At $1.27 billion, Immatics is priced as optionality, not conviction. The risk is the classic one for engagers in solid tumors: activity in a subset that never scales into a registrational path. The oncology catalyst shelf is covered.

5. The B7-H3 ADC Read-Through: Who Inherits First-to-Market

The fifth slot is a theme, not a single ticker. Merck and Daiichi Sankyo withdrew the BLA for ifinatamab deruxtecan (I-DXd) in small cell lung cancer on September 25, which blows the B7-H3 ADC field open. B7-H3 is a validated antigen with no approved drug in solid tumors, and the question is who inherits the first-to-market slot. GSK’s ris-rez, from its Hansoh deal, has an osteosarcoma Phase 3 running, and the read-through from any SITC B7-H3 ADC data re-rates the entire sub-theme.

The investable pure play is messy. GSK at $98.7 billion is a mega-cap filter, and Daiichi Sankyo’s US listing is an OTC ADR too illiquid to trade. What you can do is screen SITC for whoever presents registrational B7-H3 ADC data, because that name becomes the pure play by default. The I-DXd withdrawal and the GSK ris-rez osteosarcoma program are covered.

The Mega-Cap Filter

This list intentionally excludes the Keytruda-in-combination and Opdivo franchise updates that dominate SITC headlines, and it treats Merck’s intismeran partnership as a Moderna story rather than a $367 billion Merck story. The filter is simple: if the market cap exceeds $100 billion and the update is a franchise extension, the data moves zero basis points. GSK’s B7-H3 read-through is the exception that proves the rule, because there the value accrues to the field, not the ticker.

The Catalyst-Consumed Caveat

The I-DXd BLA withdrawal already happened on September 25, so that catalyst is in the rear-view mirror. The ivonescimab PDUFA resolves November 14, which is after SITC, so the trade is to screen SITC data ahead of the decision and let the PDUFA be the follow-through. Do not confuse the two.

The playbook is the conference trading guide: abstract release is the trade date, position size 1-2% of portfolio per binary event, and the 24-hour rule applies after the embargo lifts.

The verdict: Summit ivonescimab is the name that actually re-rates, because SITC data lands between now and a $12.45 billion PDUFA, and any OS confirmation in the Western population tightens the odds on a decision that is already two weeks out. Iovance is the second, because TIL expansion beyond melanoma is the one dataset that can change the platform thesis. Moderna and Immatics are screens, not buys, and the B7-H3 read-through is a field-level signal rather than a single ticker. That is the whole list.