Adaptimmune has seen partial responses in three of the first four myxoid/round cell liposarcoma (MRCLS) patients treated with its T cells. The early data raised hopes the GlaxoSmithKline-partnered drug will be effective in multiple types of solid tumor, sending Adaptimmune shares up nearly 20%.

Abingdon, U.K.-based Adaptimmune first posted clinical data linking NY-ESO SPEAR T cells to responses in synovial sarcoma patients in 2015. Those results gave Adaptimmune preliminary validation that it can engineer T cells to take out solid tumors but left the biotech needing more evidence to show its platform is effective against a range of cancers.

The MRCLS data mark a small step toward that goal. MRCLS, like synovial sarcoma, is a soft-tissue sarcoma but the underlying genetics and clinical manifestations of the two diseases are different.

Having treated four MRCLS patients with NY-ESO SPEAR T cells, Adaptimmune has seen two partial responses, one unconfirmed partial response and one case of stable disease. The size of the dataset and fact the short-running study is yet to demonstrate the durability of the responses mean plenty of questions remain unanswered. But the findings move Adaptimmune in the right direction.

Investigators saw cytokine release syndrome (CRS), the inflammatory response that has dogged early cell therapy trials, but it was managed using standard treatment guidelines. Adaptimmune CEO James Noble sees the handling of CRS in recent trials as evidence doctors have got a handle on the side effect.

“In qualified centers such as the centers where we operate and most gene therapy is done, there are already very clear algorithms for treatment and initiation of tocilizumab and secondary agents including steroids. The whole field has learned how to manage this,” Noble told investors on call to discuss the data.

The safety and efficacy outcomes have a positive readthrough for Adaptimmune’s pipeline. Together with GSK, the British biotech is testing NY-ESO SPEAR T cells in a range of cancers, including ovarian and non-small cell lung cancer. GSK exercised its option on the asset last year and is in the process of taking ownership of its development.