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Achilles Therapeutics Reports Initial Data from Engineered Cell Therapy Trials in Melanoma, NSCLC

NEW YORK – Achilles Therapeutics said on Friday that after reviewing interim data from the company's Phase I/IIb Chiron and Thetis clinical trials, an independent data and safety monitoring committee has recommended that both trials continue as planned.

The clinical trials are both designed to evaluate the safety and tolerability of Achilles' T-cell therapies, which are autologous treatments designed to target patients' unique clonal neoantigens. This therapy, which Achilles has dubbed cNeT, is being assessed as a treatment for patients with metastatic melanoma and advanced non-small cell lung cancer in the Thetis and Chiron trials, respectively. In addition to evaluating the treatment's safety and tolerability in these studies, researchers will also consider secondary outcome measures such as change in baseline tumor size and duration of response, among others.

Though the Thetis and Chiron trials are ultimately expected to enroll 40 and 50 patients, respectively, this interim review included data only from the first six patients dosed with Achilles' cNeTs. According to the UK-based company, the tolerability observed among these six patients was generally comparable to the tolerability observed with tumor-infiltrating lymphocyte (TIL) therapies that are not enriched for the clonal neoantigen targets. The more serious adverse events observed were due to the lymphodepleting regimen that patients received prior to the cell therapy infusion rather than to the treatment itself.

Six weeks after these patients were infused with the treatment, Achilles reported that four patients out of six experienced stable disease. One patient who had four tumor lesions experienced a 55 percent and 90 percent reduction in the size of two of these lesions.

Among four patients for whom engraftment data were available, moreover, two patients had evidence of engraftment. The greatest tumor reduction and highest engraftment were observed in the patient who received the highest dose of the cNeTs.

Based on these data, Achilles plans to begin increasing the dose of the cell therapies among enrolled patients in the second half of 2021. Additionally, in the melanoma-focused Thetis trial, the company plans to begin enrolling patients to an additional arm that combines the cNeTs with a PD-1 inhibitor.

The early results come in the wake of a November announcement that Achilles had raised $69.6 million in a Series C financing round. The company said it intended to use those funds to advance its cNeT therapies and eventually expand the drug into other tumor types beyond melanoma and NSCLC.