Amendment Accepted By FDA, Enhancing and Upgrading the Trial

41 US Clinical Trial Sites Now In Operation

BETHESDA, MD, May 17, 2012 — Northwest Biotherapeutics (OTC.BB: NWBO) (NW Bio) announced today that it now has 41 clinical trial sites open and recruiting across the United States in its ongoing clinical trial of DCVax®-L immune therapy for Glioblastoma multiforme (GBM), the most lethal form of brain cancer. This is ahead of the Company’s previous projection of 40 sites by the end of Q2, 2012. The Company plans to continue adding clinical trial sites in the US and Europe, and expects to have at least 60 sites open and enrolling by the end of Q3, 2012.

The Company also announced that the FDA has accepted an amendment of the clinical trial, which does not make any change in the treatment regimen, which leaves all data collected to date intact for use in the trial’s overall results, and which includes the following:

• Designation as a Phase III trial
• Expanded and enhanced statistical endpoint analyses
• Addition of another cohort of patients which can potentially expand the application
  of DCVax®-L, and which increases the trial to up to 300 patients
• Addition of interim analyses for efficacy

A description of the trial protocol as amended will be available at www.clinicaltrials.gov.

Linda Powers, CEO of Northwest Bio, commented, “Of course, the evolution of this trial to a Phase III trial is no assurance of the outcome, and more than one Phase III trial can often be required for a product approval unless the clinical results are particularly strong. However, we are pleased to make this transition to Phase III, and believe that the package of amendments further enhances an already strong trial, positioning the Company to realize the potential of the DCVax®technology.”

Ms. Powers added, “We are excited about the operational progress we have made on multiple fronts, through long periods of work building to these points, as described in our recent announcements. Our lead clinical trial has grown and emerged as a 300-patient, international Phase III trial involving some of the best institutions in the US, UK and Germany. We are also working on several other initiatives, and will provide reports when milestones are reached in those programs.”

For further information about the Company and its programs, please visit the Company’s website
at www.nwbio.com.

About Northwest Biotherapeutics

Northwest Biotherapeutics is a biotechnology company focused on developing immunotherapy products to treat cancers more effectively than current treatments, without toxicities of the kind associated with chemotherapies, and on a cost-effective basis, in both the United States and Europe. The Company has a broad platform technology for DCVax® dendritic cell-based vaccines. The Company’s lead clinical trial is a Phase III trial, with up to 300 patients with newly diagnosed GBM for whom surgery is indicated. GBM is the most aggressive and lethal brain cancer. The Company also previously received clearance from the FDA for a 612-patient Phase III trial in prostate cancer, and clearance from the FDA for Phase I/II trials in multiple other cancers. The Company has also conducted a Phase I/II trial with DCVax® for metastatic ovarian cancer.

Disclaimer

Statements made in this news release that are not historical facts, including statements concerning future treatment of patients with GBM using DCVax® and future clinical trials, are forwardlooking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “expect,” “believe,” “intend,” “plan,” “continue,” “may,” “will,” “anticipate,” and similar expressions are intended to identify forward-looking statements. Actual results may differ materially from those projected in any forward-looking statement. Specifically, there are a number of important factors that could cause actual results to differ materially from those anticipated, such as the Company’s ability to raise additional capital, risks related to the Company’s ability to enroll patients in its clinical trials and complete the trials on a timely basis, the uncertainty of the clinical trials process, uncertainties about the timely performance of third parties, and whether the Company’s products will demonstrate safety and efficacy. Additional information on these and other factors, including Risk Factors, which could affect the Company’s results, is included in its Securities and Exchange Commission (“SEC”) filings. Finally, there may be other factors not mentioned above or included in the Company’s SEC filings that may cause actual results to differ materially from those projected in any forward-looking statement. You should not place undue reliance on any forward-looking statements. The Company assumes no obligation to update any forward-looking statements as a result of new information, future events or developments, except as required by securities laws.