MabVax Therapeutics, Inc.' Human Antibody Clinical Development Candidate HuMab 5B1 Successfully Clears Important Early Toxicology Testing

SAN DIEGO, May 5, 2015 /PRNewswire/ -- MabVax Therapeutics Holdings, Inc. (OTCQB: MBVX), a clinical stage oncology drug development company, announced today it has received the final report on toxicology testing of its HuMab 5B1 antibody, which was completed by a leading independent contract research organization.  The report detailed that the antibody, given in either a single dose or repeated doses, had no significant adverse findings even at the highest dosage levels tested. These results further validate the Company's decision to advance HuMab 5B1 into Phase 1 clinical trials before the end of 2015.

David Hansen, President and CEO of MabVax Therapeutics, explained, "We challenged the non-human primates in this acute dose range finding study with multiple dose levels to assess drug pharmacokinetics, as well as with repeated doses of the antibody to identify any adverse toxicology signals.  These studies were conducted in the most relevant animal models with material produced by our GMP manufacturing partner.  The antibody as tested is representative of the clinical supply material scheduled for delivery later this year.  As the final report provided evidence that there were no significant adverse findings, we are moving forward with our plan to enter the clinic later this year. Because the HuMab 5B1 antibody is fully human recovered from patients undergoing cancer vaccine treatment at Memorial Sloan-Kettering Cancer Center, we believe that these antibodies reduce the likelihood of unwanted immunogenicity and cross reactivity.  These results continue to build the body of evidence that makes our HuMab 5B1 product a valuable asset."

The clinical development plan calls for two Phase I clinical trials to begin late this year.  One program will determine the safety and potential utility of HuMab 5B1 in subjects with metastatic pancreatic cancer as a single agent or in combination with the current standard of care.  The second program will be aimed at demonstrating the utility of ⁸⁹Zr-HuMab 5B1, our radiolabeled HuMab 5B1 antibody, as a next generation PET imaging agent for the diagnosis and management of pancreatic cancer.

Mr. Hansen continued, "We are excited about the potential of utilizing a therapeutic antibody in combination with a companion diagnostic agent.  We believe this unique dual-product development approach is applicable to other cancers utilizing our HuMab 5B1 antibody as well as with follow-on antibodies already under development in our preclinical pipeline."

About HuMab 5B1:
In pre-clinical research MabVax's HuMab 5B1 antibody has demonstrated high specificity, affinity, and lack of cross-reactivity with closely related antigens.  The antibody has also shown potent cancer cell killing capacity and efficacy in animal models of pancreatic, colon, and small cell lung cancer. When combined with a radio-label as a novel PET imaging agent, ⁸⁹Zr-HuMab 5B1 has demonstrated high image resolution of tumors in established xenograft animal models, making it attractive as a companion diagnostic for the therapeutic product.

About MabVax:
MabVax Therapeutics Holdings, Inc. is a clinical stage biotechnology company focused on the development of vaccine and antibody based to address unmet medical needs in the treatment of cancer.  MabVax has discovered a pipeline of human monoclonal antibody products based on the protective immune responses generated by patients who have been immunized against targeted cancers with the Company's proprietary vaccines. MabVax also has the exclusive license to the therapeutic vaccines from Memorial Sloan Kettering Cancer Center.  MabVax has two cancer vaccines targeting recurrent sarcoma and ovarian cancer in proof of concept Phase II multi-center clinical trials, and a vaccine targeting neuroblastoma that will be ready for Phase II clinical trial later this year. Additional information about the Company is available at www.mabvax.com.

Forward Looking Statements
This press release contains "forward-looking statements" regarding matters that are not historical facts, including statements relating to the Company's development pipeline.  We have no assurance that all of the product development pipeline will be fully developed by the Company.   Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements.  Words such as "anticipates," "plans," "expects," "intends," "will," "potential," "hope" and similar expressions are intended to identify forward-looking statements.  These forward-looking statements are based upon current expectations of the Company and involve assumptions that may never materialize or may prove to be incorrect.  Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of various risks and uncertainties.  Detailed information regarding factors that may cause actual results to differ materially from the results expressed or implied by statements in this press release relating to the Company may be found in the Company's periodic filings with the Securities and Exchange Commission, including the factors described in the section entitled "Risk Factors" in its annual report on Form 10-K for the fiscal year ended December 31, 2014, as amended and supplemented from time to time and  the Company's Quarter Reports on Form 10-Q and other filings submitted by the Company to the SEC, copies of which may be obtained from the SEC's website at www.sec.gov.  The parties do not undertake any obligation to update forward-looking statements contained in this press release.

Investor Contact:

Robert B. Prag, President
The Del Mar Consulting Group, Inc.
858-794-9500
bprag@delmarconsulting.com

or

Scott Wilfong, President
Alex Partners, LLC
425-242-0891
scott@alexpartnersllc.com

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SOURCE MabVax Therapeutics Holdings, Inc.