1051P - Intratumoral injection of LTX-315 in combination with pembrolizumab in patients with advanced melanoma refractory to prior PD-1/PD-L1 therapy: Interim results from the ATLAS-IT-05 trial

Background

LTX-315 is an oncolytic peptide of non-viral origin that is in clinical development for the treatment of solid tumors. We investigated whether treatment with LTX-315 in combination with pembrolizumab is safe and efficacious.

Methods

This open-label, single-arm phase II trial includes patients with stage IIIB-stage IVm1b (without liver metastases) metastatic melanoma, who have progressed on or after after PD-1/PD-L1 inhibitor therapy. In Part A, patients receive intratumoral LTX-315 injections (5 mg per injection and up to 40 mg total) on up to 7 treatment days over 5 weeks and pembrolizumab (200 mg i.v.) on Days 1 and 22. In Part B, pembrolizumab (400 mg i.v.) is given every 6 weeks starting at Day 43 until maximum 24 months. The primary objective is antitumor activity assessed by the investigators using RECIST v1.1 criteria. Secondary objectives include safety data.

Results

At the cutoff date of 24 April 2023, 14 of 20 planned patients have been enrolled and treated: 13 patients with metastatic melanoma and 1 patient with advanced acinic cell carcinoma (included under an earlier protocol version). Mean age of enrolled patients was 64 years and 50% had received 2 or more prior systemic anti-cancer therapies. Preliminary antitumor activity was evaluable in 7 patients who had ≥1 post-baseline scan available at the cutoff date. The Overall Response Rate was 14% with 1 patient with partial response. Disease Control Rate was 43%. All 14 enrolled patients had received ≥1 LTX-315 injection and ≥1 pembrolizumab infusion and were included in the interim Safety Population. Treatment-emergent adverse events (TEAEs) were reported in 11 patients (79%). The most common (≥10%) TEAEs related to LTX-315 were mild to moderate injection site pain (50%) and asthenia (14%). There was no increase in immune-related adverse events.

Conclusions

Intratumoral LTX-315 administration in combination with pembrolizumab appears to be well tolerated and showed preliminary efficacy in patients with advanced melanoma. Updated efficacy and safety data will be presented at the conference.

Clinical trial identification

NCT04796194.

Editorial acknowledgement

Legal entity responsible for the study

Lytix Biopharma AS.

Funding

Lytix Biopharma AS.

Disclosure

S. Dalle: Financial Interests, Institutional, Advisory Board: MSD, BMS; Financial Interests, Institutional, Research Grant: BMS, MSD. T.U. Marron: Financial Interests, Personal, Advisory Board: Regeneron, AbbVie, Merck, BMS, Boehringer Ingelheim, Atara, AstraZeneca, Genentech, Celldex, Chimeric, Glenmark, Simcere, Surface, G1 Therapeutics, NGMbio, DBV Technologies, Arcus, Astellas; Financial Interests, Personal and Institutional, Research Grant: Regerenor, BMS, Merck, Boehringer Ingelheim. C. Robert: Financial Interests, Personal, Other, Consultancy fees: BMS, ROCHE, PIERRE FABRE, NOVARTIS, SANOFI, MSD, ASTRAZENECA, PFIZER. M.S. Nyakas: Financial Interests, Personal, Speaker, Consultant, Advisor: BMS, MSD, Pierre Fabre, Novartis. K. Bruins Slot: Financial Interests, Personal, Full or part-time Employment: Lytix Biopharma AS. V. Sundvold: Financial Interests, Personal, Full or part-time Employment: Lytix Biopharma. î Rekdal: Financial Interests, Personal, Full or part-time Employment: Lytix Biopharma; Financial Interests, Personal, Stocks/Shares, Lytix Biopharma: Lytix Biopharma. B. Sveinbjornsson: Financial Interests, Personal, Full or part-time Employment: Lytix Biopharma; Financial Interests, Personal, Stocks/Shares: Lytix Biopharma. G. Currie: Financial Interests, Personal, Full or part-time Employment: Pasithea Therapeutics; Financial Interests, Personal, Advisory Role: Lytix Biopharma, Nanotics LLC; Financial Interests, Personal, Stocks/Shares: Regeneron Pharmaceuticals, Gilead; Financial Interests, Personal, Proprietary Information: Rainier Therapeutics. All other authors have declared no conflicts of interest.