Approved in Japan (September 2020, unresectable locally advanced or recurrent head and neck cancer) · Combination with immunotherapy in clinical trials (global phase 3 ongoing) Sources: ESMO 2026 presentation, phase 1b/2 registry, ASCO 2026 Japanese real-world report
Photoimmunotherapy combined with immunotherapy pairs light-activated photoimmunotherapy (ASP-1929) with the immune checkpoint inhibitor pembrolizumab (Keytruda). Long-term phase 1b/2 results in recurrent or metastatic head and neck cancer, with more than four years of follow-up, were presented at ESMO 2026 on October 23, 2026. Five of 17 evaluable patients (29%) achieved a complete response, and median overall survival was 28.2 months.
What was announced?
Rakuten Medical presented an e-poster at ESMO 2026 with long-term follow-up from the phase 1b/2 ASP-1929-181 study (NCT04305795) of ASP-1929 (marketed in Japan as Akalux; cetuximab sarotalocan) plus pembrolizumab. The data cutoff was February 10, 2026, and median follow-up grew from 31.7 months in the earlier analysis to 53.1 months.
The key message is durability. Four of the five complete responders were alive with follow-up ranging from more than 42 to more than 60 months, and the median duration of response was 44.3 months. No new safety signals were observed.
Why combine the two treatments?
Photoimmunotherapy uses a drug and light together. An antibody that binds EGFR on cancer cells is linked to a light-sensitive dye and given intravenously; about a day later, red laser light at 690 nm is shone on the tumor. Cancer cells carrying the drug suffer membrane damage and die quickly. For how this differs from other light treatments, see PDT vs photoimmunotherapy.
Dying cancer cells release tumor antigens, making the cancer easier for immune cells to recognize. Pembrolizumab releases the PD-1 “brake” that tumors place on immune cells. Light destroys the tumor directly and the checkpoint inhibitor supports the immune attack that follows, which is why the two are being tested together.
In the study, pembrolizumab 200 mg was given intravenously on days 1 and 22 of each 6-week cycle, and ASP-1929 was given on day 8 of each cycle, followed by light. Treatment could continue for up to 24 months.
Who was treated?
The study enrolled 19 patients with recurrent or metastatic head and neck squamous cell carcinoma, of whom 17 were evaluable for efficacy. This includes cancers of the tongue and mouth, pharynx and larynx.
Because light must reach the tumor, its location matters. Your medical team decides suitability using imaging of tumor position, size and nearby blood vessels. Results of photoimmunotherapy alone are summarized in head and neck photoimmunotherapy results.
What did 4-year follow-up show?
The figures below are taken directly from the ESMO 2026 presentation.
| Measure | Result |
|---|---|
| Enrolled / evaluable patients | 19 / 17 |
| Median follow-up | 53.1 months (previously 31.7 months) |
| Median overall survival | 28.2 months |
| Estimated 3-year / 4-year survival | 47.1% / 35.3% |
| Complete response | 5 patients (29%); 4 alive at more than 42 to more than 60 months |
| Median duration of response | 44.3 months |
| Responders free of further anticancer therapy after study treatment | 4 patients |
Source: Rakuten Medical, ESMO 2026 (2026-10-23), data cutoff 2026-02-10. Single-arm phase 1b/2 results without a comparison group.
Exploratory analyses by HPV status, PD-L1 expression and baseline tumor size were broadly consistent. Because patient numbers are small, subgroup results should be read as supportive only. Safety remained manageable as in the earlier analysis, and no new safety signals appeared with longer follow-up.
Real-world results from Japan
In Japan, photoimmunotherapy alone has been used under national health insurance since 2020. At ASCO 2026 in June, a Japanese nationwide study (UMIN000060367) of 43 patients with recurrent nasopharyngeal cancer was presented.
- 31 of 43 patients (72.1%) had a local complete response lasting at least 2 months and 6 (14.0%) a partial response, for a local response rate of 86.0%.
- Two-year overall survival was 89.2%, and 22 patients (51.2%) were alive with no evidence of disease at last follow-up.
- Grade 3 or higher adverse events occurred in 10 patients (23%), most often osteomyelitis and mucositis. Two patients died of carotid hemorrhage possibly linked to osteomyelitis, so careful monitoring for bleeding after treatment is important.
More on care in Japan: head and neck cancer information and photoimmunotherapy information.
Where is it available?
Japan’s Ministry of Health, Labour and Welfare approved photoimmunotherapy alone in September 2020 under the SAKIGAKE designation and Conditional Early Approval systems, and patients with unresectable locally advanced or recurrent head and neck cancer are treated at Japanese hospitals. It is not yet approved outside Japan and is used there in clinical trials.
For the combination, the global phase 3 ASP-1929-381 trial (NCT06699212) is ongoing. It tests ASP-1929 plus pembrolizumab as first-line treatment for locoregional recurrent head and neck cancer in about 400 patients in the United States, Taiwan, Japan and Ukraine. Rakuten Medical plans to submit a Biologics License Application to the US FDA in 2028 after the trial is completed.
Questions for your doctor
- Is my tumor in a position and size that laser light can reach?
- Do I meet the conditions for photoimmunotherapy alone in Japan?
- Can we check the sites and eligibility for the global phase 3 combination trial?
- How will pain, swelling or bleeding after treatment be managed, and when should I call right away?
FAQ
Does combining photoimmunotherapy with Keytruda work better?
In the phase 1b/2 study, 5 of 17 evaluable patients achieved a complete response and median overall survival was 28.2 months. Because this was a small single-arm study, a direct comparison with photoimmunotherapy alone will come from the ongoing global phase 3 trial.
What are the side effects of the combination?
No new safety signals were seen with long-term follow-up, and safety was reported as manageable, as in the earlier analysis. Pain and swelling at the treated site and immune-related thyroid or skin effects are monitored with regular visits and tests.
Can I receive the combination in Japan?
Japan has approved photoimmunotherapy alone. The pembrolizumab combination is being studied in a global phase 3 trial that includes Japan, so eligible patients may receive it by joining the trial.
Which head and neck cancer patients are candidates for photoimmunotherapy?
In Japan it is approved for unresectable locally advanced or recurrent head and neck cancer. Whether light can reach the whole tumor is key, and your medical team assesses this with imaging.
Related: Head and neck photoimmunotherapy results · Same “photoimmuno” name, different treatments · mRNA cancer vaccine guide
Sources
- Rakuten Medical — Long-term follow-up results of ASP-1929 photoimmunotherapy in combination with pembrolizumab for R/M HNSCC at ESMO 2026 (2026-10-23)
prnewswire.com
Checked: 2026-10-26 - The Clinical Trial Vanguard — ASP-1929 + pembrolizumab shows 28-month median OS in HNSCC study (2026-10-23)
clinicaltrialvanguard.com
Checked: 2026-10-26 - Rakuten Medical — New data on ASP-1929 photoimmunotherapy as monotherapy for recurrent head and neck cancer at ASCO 2026 (2026-05-30)
rakuten-med.com
Checked: 2026-10-26 - Safety and efficacy findings from a phase Ib/II study of ASP-1929 photoimmunotherapy with pembrolizumab in recurrent and/or metastatic head and neck squamous cell carcinoma (PMC12703558)
pmc.ncbi.nlm.nih.gov
Checked: 2026-10-26 - ClinicalTrials.gov — An open-label study using ASP-1929 photoimmunotherapy in combination with anti-PD1 therapy in EGFR expressing advanced solid tumors (NCT04305795)
clinicaltrials.gov
Checked: 2026-10-26 - OncLive — ASP-1929 plus pembrolizumab produces responses, proves safe in recurrent or metastatic HNSCC
onclive.com
Checked: 2026-10-26
Written by the FTH editorial team. Sources checked 2026-10-26 · Medical review: not applicable
This article is general information based on public sources and does not replace diagnosis or treatment. Please discuss treatment decisions with your medical team.
