One of the hottest companies in the sizzling cancer immunotherapy space, Adaptimmune Ltd., filed its F-1 with the SEC, seeking a $150 million IPO and a Nasdaq listing for its American depositary shares under the ticker ADAP.

The filing was just the latest evidence of a resurgence of interest in ex-U.S. biotechs, which have made a respectable showing in recent years in filings on both sides of the Atlantic. (See BioWorld Today, April 6, 2015.)

The Abingdon, UK-based company, which recently completed a corporate reorganization to exchange and issue new shares, filed under the new moniker Adaptimmune Therapeutics plc. Investors needn't worry the firm plans other changes, however. Adaptimmune, which grabbed $104 million last year in an oversubscribed series A as the follow-up to its $350 million deal with London-based Glaxosmithkline plc (GSK), remains squarely focused on advancing cancer immunotherapy candidates based on its T-cell receptor (TCR) platform.

Adaptimmune has been on a streak of good news since the company reported data in December 2013 from the open-label phase I/II trial of its autologous T-cell immunotherapy in multiple myeloma. Disclosed at the American Society of Hematology meeting in New Orleans, the 77 percent complete response rate in the 20 patients treated to date, at 100 days post-infusion, wowed spectators and brought potential partners flocking to the company.

"We are pretty much besieged at the moment," CEO James Noble told BioWorld Today at the time. (See BioWorld Today, Dec. 10, 2013.)

Since then, the British firm has laid a respectable path for its clinical pipeline, in March 2014 launching its second T-cell cancer immunotherapy product into development in the UK, in the treatment of triple negative breast cancer. That TCR product targets MAGE A-10, which is highly expressed in breast and lung cancers. (See BioWorld Today, March 25, 2014.)

In September, the company's long-awaited A round drew New Enterprise Associates, which led the round, with Orbimed Advisors LLC, Wellington Management Co. LLP, Fidelity Biosciences, Foresite Capital Management, Ridgeback Capital Management, Novo A/S, QVT, Rock Springs Capital, Venbio Select and Merlin Nexus. Existing investors, including Oxford University, put in $4 million. (See BioWorld Today, Sept. 25, 2014.)

The financing came on the heels of the GSK deal, in which the partners agreed to collaborate on Adaptimmune's lead product, in which a patient's T cells are engineered against the NY-ESO-1 cancer testis antigen. Once the candidate completes phase II proof of concept, GSK has an option to take a full license. (See BioWorld Today, June 2, 2014.)

In October, Adaptimmune released the first positive clinical data of its second-generation T-cell immunotherapy in a solid tumor, reporting four of five patients with advanced synovial sarcoma responded to treatment. Eight of 10 patients in the single-arm, open-label study had been treated with their own T cells, genetically engineered to express a high-affinity T-cell receptor targeting NY-ESO, using Adaptimmune's manufacturing technique.

Of the five patients to have reached the 60-day time point for assessment of clinical response, one had shown a complete response and three showed partial responses. (See BioWorld Today, Oct. 17, 2014.)

The data, though early, were said to provide the first indication that Adaptimmune's immunotherapy approach can target solid tumors, setting it apart from companies in the chimeric antigen receptor, or CAR T space, which has largely targeted hematological or liquid tumors.

In its filing, Adaptimmune said funds from the IPO will accelerate the development of the MAGE A-10 TCR candidate through phase I/II trials, enable pilot manufacturing for clinical trials and fund operations for several years. The company also plans to begin a feasibility assessment of a commercially viable manufacturing platform for its TCR candidates and to advance additional TCR candidates into preclinical testing. Adaptimmune has preclinical work under way on a TCR therapeutic candidate that is directed to alpha fetoprotein, or AFP.

The company reported cash and equivalents of £65.2 million (US$96.6 million) as of Dec. 31.

BofA Merrill Lynch, Cowen and Co. LLC and Leerink Partners LLC are joint bookrunners on the deal, which was not priced.

Adaptimmune was joined in the IPO queue by Atyr Pharma Inc., of San Diego, which filed an S-1 seeking to raise up to $86.25 million, including overallotments, just days after closing a $76 million series E round designed to propel its pipeline, led by an ongoing phase Ib/II trial of the restorative protein therapy, Resolaris (ATYR-1940), for patients with the rare facioscapulohumeral muscular dystrophy. (See BioWorld Today, April 2, 2015.)

The company maintains that physiocrines – extracellular signaling regions of transfer ribonucleic acid synthetases – can promote restoration of stressed or diseased tissue to a healthier state.

Its investment syndicate includes Sofinnova Ventures, funds and accounts advised by T. Rowe Price Associates Inc., Federated Investors Inc., Deerfield, Rock Springs Capital Management, Ecor1 Capital and Sphera Global Healthcare.

The number of shares and price range in Atyr's offering were not disclosed. The company applied for a Nasdaq listing under the ticker LIFE.

In its filing, the company reported cash and equivalents of $15.9 million and an accumulated deficit of $110.2 million as of Dec. 31.

J.P. Morgan Securities LLC and Citigroup Global Markets Inc. were named as lead bookrunners, with BMO Capital Markets Corp. as lead manager and William Blair & Co. LLC as co-manager.