Benzinga | Nov 9, 2020 03:20PM EST

Adaptimmune Reports 2 Confirmed Responses, 5 Out Of 6 Patients With Initial Tumor Reductions From Early Dose Cohorts Of SURPASS Trial, Presented Data In Poster At Society For Immunotherapy Of Cancer Meeting

Adaptimmune Therapeutics plc (NASDAQ:ADAP), a leader in cell therapy to treat cancer, presented data from the dose escalation cohorts of its Phase 1 SURPASS trial using ADP-A2M4CD8 in a poster at the Society for the Immunotherapy of Cancer ("SITC") Conference.

In these cohorts of heavily pre-treated patients with advanced cancers (n=6), three were treated with target doses of 1 billion SPEAR T-cells, and three with target doses of 5 billion. Most adverse events were consistent with those typically experienced by cancer patients undergoing cytotoxic chemotherapy or cancer immunotherapy.

"We have seen responses in two out of six patients treated in the safety cohorts of the SURPASS trial as well as antitumor activity in five of them. The responses and antitumor activity we have seen with our next-generation ADP-A2M4CD8 SPEAR T-cells, across a range of solid tumors, support our belief that this is a highly active product," said Ad Rawcliffe, Adaptimmune's Chief Executive Officer. "Based on these data, we will initiate the Phase 2 trial in gastroesophageal cancers in the first half of 2021 and look forward to identifying additional indications to take into late-stage development."

There were two confirmed partial responses (PRs): one in a patient with esophagogastric junction (EGJ) cancer, previously reported, and one in a patient with head and neck cancer, reported as unconfirmed in May. The four other patients had best overall responses of stable disease (SD). Overall, five out of six patients treated had initial tumor shrinkage.

In vitro translational data using the manufactured products from patients in the SURPASS trial indicate that co-expression of the CD8? co-receptor on CD4+ ADP-A2M4 SPEAR T-cells enables them to kill MAGE-A4 expressing target cells with equal potency as CD8+ SPEAR T-cells targeting MAGE-A4. These data, combined with the responses and antitumor activity observed at low doses, indicate that ADPA2M4D8 may be a more potent product than the first-generation ADPA2M4 SPEAR T-cells.

Best Overall Response (BOR) and maximum changes from baseline in target lesions in Cohorts 1 and 2

Indication Dose x 109 BOR Tumor reductionHead and neck 4.6 PR -63.16%EGJ 1.2 PR -51.52%EGJ 1.0 SD -34.07%Ovarian 1.1 SD -16.13%Esophageal 6.0 SD -13.37%MRCLS 5.7 SD +1.35%

As of data cut-off: October 1, 2020

At SITC, Adaptimmune also presented a poster entitled "Inhibition of AKT signaling during expansion of TCR-engineered T-cells from patient leukocyte material generates SPEAR T-cells with enhanced functional potential in vitro." These preclinical data indicate that AKT inhibition during the manufacture of SPEAR T-cells results in a more consistent expansion and phenotype of the final product. This process is currently being used for manufacture of ADP-A2M4CD8 for the SURPASS trial.

The Company also presented two posters summarizing data for the two completed Phase 1 trials with ADP-A2M10 (a previously terminated program).