Marker Therapeutics, Inc. ( MRKR ) on Tuesday provided an update on the progress and clinical observations from the Phase 1 APOLLO study investigating MT-601, a Multi-Antigen Recognizing (MAR)-T cell product, in patients with lymphoma who have relapsed after anti-CD19 CAR-T cell therapy or for whom anti-CD19 CAR-T cell therapy is not an option.

Last year, Marker Therapeutics ( MRKR ) restructured its clinical programs and prioritized MT-601.

Marker reported an update on the safety and efficacy data from the dose escalation portion of the study, showing a favorable safety profile across all evaluated doses (dose range 100×106 – 400×106 cells) and a 66% objective response rate in patients with NHL, with 50% demonstrating complete response.

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A total of 24 B-cell lymphoma patients have been treated with MT-601, including 15 patients with Non-Hodgkin Lymphoma (NHL) and nine patients with Hodgkin Lymphoma (HL).

At the time of the data cutoff (June 2025), 12 NHL and nine HL patients have been assessed.

Patients with NHL and HL received doses ranging from 100×106 – 400×106 cells and showed objective responses and a favorable safety profile.

Efficacy and Duration of Response

The 12 NHL patients received doses ranging from 100×106 – 200×106 cells and had undergone multiple lines of therapy.

Eight out of 12 NHL patients had objective responses (66%), with six patients demonstrating a complete response (CR) as best response (50%).

Durable responses were observed (range three–24 months) with five patients showing continued response ≥6 months, including three patients with ≥12 months durability.

HL patients received doses ranging from 200×106 – 400×106 cells and had undergone a median of eight prior lines of therapy.

Seven out of nine HL patients had objective responses (78%), with one patient demonstrating CR (11%), highlighting the versatility of MT-601 across multiple histologies.

Safety Profile

The dose escalation portion of the study tested doses ranging from 100×106 – 400×106 cells in patients with B-cell lymphoma.

No dose-limiting toxicities (DLTs) have been reported at the highest dose (400×106 cells).

Infusion of MT-601 was well tolerated in all study participants, with no observation of ICANS and two reported Grade 1 cytokine release syndrome (CRS) events (fever; no treatment was required).

Patients were treated with or without lymphodepleting chemotherapy before receiving infusions of MT-601.

No change in DLTs or ICANS was observed between patients treated with and without lymphodepletion.

Data collected from the 24 patients treated demonstrated a robust safety profile with no reported serious adverse events.

The company anticipates providing another data update in the first half of 2026.

MRKR Price Action: Marker Therapeutics ( MRKR ) stock is down 14.28% at $1.08 at publication on Tuesday.

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