LONDON, Sept. 26, 2019 (GLOBE NEWSWIRE) -- Treos Bio Limited, which is developing personal cancer vaccines combined with companion diagnostic devices, reported updated positive results on the second part of its phase 1/2 study (OBERTO) with the PolyPEPI1018 cancer vaccine as an add-on to maintenance therapy in patients with microsatellite-stable (MSS) metastatic colorectal cancer (mCRC).
The results will be presented at the 2019 European Society of Medical Oncology (ESMO) annual congress in Barcelona on September 29, 2019 in the Gastrointestinal tumors, colorectal poster session, entitled: “Evaluation of safety, immunogenicity and preliminary efficacy of PolyPEPI1018 vaccine in subjects with metastatic colorectal cancer (mCRC) with a predictive biomarker.”
PolyPEPI1018 is an off-the-shelf, synthetic long peptide vaccine containing immunogenic fragments of seven conserved cancer testis antigens (CTAs) frequently expressed in mCRC. PolyPEPI1018 was designed to induce polyvalent T cell responses in a large subpopulation of CRC patients using Treos Bio’s proprietary PASCal computational tool, which identifies Personal EPItopes (PEPIs) that are likely to induce antigen-specific T cell responses in a subject.
The phase 1/2 study is an open-label, single-arm, multicenter study to evaluate the safety, tolerability, immunogenicity and preliminary efficacy of single dose (first part of the study) or multiple doses (second part of the study) of PolyPEPI1018 as an add-on to maintenance therapy in patients with metastatic colorectal cancer after first-line induction chemotherapy (NCT03391232). Preliminary results from the first part of the study were presented at ASCO 2019 and results of the second part of the study are available now.
mCRC patients in first line setting received up to three doses of PolyPEPI1018 vaccine (0.2 mg/peptide) 12 weeks apart, just after the transition to maintenance therapy with fluoropyrimidine and bevacizumab. Vaccine-specific T cell responses were first predicted by PEPI test (using the patient’s complete HLA genotype) then measured after one cycle of vaccination.
Eleven patients were vaccinated with PolyPEPI1018. The vaccine was well tolerated; common adverse events were transient skin reactions and flu-like syndrome. No grade 3+ adverse events related to the vaccine occurred. A total of 80 percent of patients had CD8+ T cell responses against at least three of the seven vaccine antigens, and ex vivo responses (both CD8 and CD4) could be detected in almost 90 percent of evaluated patients. Circulating vaccine-induced polyfunctional T cells were detected after a single dose and their frequency increased after multiple vaccinations. PEPI test correctly predicted ELISpot-measured CD8+ T cell responses.
Previously reported objective tumor responses observed after 12 weeks of administering a single dose were maintained during the whole 38-week period of the study. Of the five patients who received at least two doses of the vaccine, three experienced Stable Disease and two had unexpected tumor size reduction of whom one patient experienced complete tumor shrinkage on two of three target lesions and partial response on one lesion. Patients experiencing tumor shrinkage had higher number of predicted antigens than those without tumor response.
“Besides the unexpected tumor responses observed for some of the patients, it is very encouraging that the majority of patients on multiple doses controlled their disease until the end of the follow-up period and beyond,” said Joleen M. Hubbard M.D., principal investigator of the OBERTO trial at the Mayo Clinic. “We plan to continue enrollment of further patients in the study and follow them for an even longer period this time.”
In addition to the poster display of the OBERTO trial results, three other posters will be presented by Treos Bio at ESMO 2019 related to its PEPI based platform technology and science. The poster entitled “Personal Antigen Selection Calculator (PASCal) for the design of personal cancer vaccines” will be presented in the ‘Immunotherapy of Cancer’ poster discussion session on September 28, 2019.
“We believe that the unprecedented immunogenicity observed with our ‘off-the-shelf’ and ‘personalized’ vaccines is a result of our conviction that a patient’s complete HLA genotype is a major determinant of immune responses against cancer,” said Dr. Eniko R. Toke, Chief Scientific Officer of Treos Bio. “We are very excited by the potential of PEPIs as candidate genetic biomarkers in the development of highly immunogenic vaccines for a range of cancer indications and for the prediction of individuals’ immunogenetic risk of developing cancer.”
More detailed scientific and clinical data will be presented at the meeting.
ESMO 2019 POSTER SESSION: Gastrointestinal tumors, colorectal
Evaluation of safety, immunogenicity and preliminary efficacy of PolyPEPI1018 vaccine in subjects with metastatic colorectal cancer (mCRC) with a predictive biomarker (Dr. Hubbard)
Poster 606P; Hall 4, Sunday, September 29, 12.00 – 13.00am CET
ESMO 2019 POSTER DISCUSSION SESSION: Immunotherapy of cancer
Personal Antigen Selection Calculator (PASCal) for the design of personal cancer vaccines (Dr. Somogyi)
Poster Discussion 1181PD; Bilbao Auditorium; Hall 5, Saturday September 28, 16.30 CET
ESMO 2019 POSTER SESSION: Biomarkers
Inferring the correlation between incidence rates of melanoma and the average tumor-specific epitope binding ability of HLA class I molecules in different populations (Dr. Miklos)
Poster 1423P; Hall 4, September 30, 12.00-13.00 CET
ESMO 2019 POSTER SESSION: Translational research
Computational model to predict response rate of clinical trials (Dr. Lorincz)
Poster 1935P, Hall 4, September 30, 12.00-13.00 CET
The full abstracts are available at https://cslide.ctimeetingtech.com/esmo2019/attendee/confcal/presentation/list?q=treos and at http://treosbio.com/index.php/publications-2/. The presentations will be available at www.treosbio.com on 30 September 2019 at 13.00 CET.
About Colorectal Cancer
Colorectal cancer is the third most common cancer worldwide, accounting for one-third of the cancer incidence and mortality burden worldwide together with lung and breast cancers with nearly 881,000 deaths in 2018 from colorectal cancer worldwide, according to GLOBOCAN. While improvements in cancer care have boosted survival rates for all stages of colorectal cancer in the past two decades, the prognosis for patients with metastatic colorectal cancer remains grim. The five-year relative survival rate for patients with metastatic colon cancer is just 14 percent. For patients with metastatic rectal cancer, the five-year relative survival rate is just 15 percent, according to the American Cancer Society.
About Treos Bio Limited
Treos Bio, headquartered in London, with operational subsidiaries in Hungary and the USA uses data science and proprietary biomarkers to develop its precision cancer vaccines, with substantially shortened development timelines and at lower costs. Treos Bio’s off-the-shelf cancer vaccines are designed to exclude autoimmunity and induce tumor specific immune responses to be safer and more effective in patients who cannot benefit from current immunotherapies. Treos Bio’s novel biomarkers will support the development of in vitro companion diagnostic tests to identify patients who are most likely to respond to treatment.
Treos Bio has completed preclinical development of additional members of the PolyPEPI cancer vaccine family with companion diagnostics to select likely responders. These off-the-shelf vaccines are designed for a general population of patients with ovarian-, breast-, lung cancers, glioma, melanoma, and leukemia. Treos Bio patient focused vaccine design also supports the development of vaccines for single individuals and a population of individuals with a specific genetic background, including specific vaccines most effective in ethnic populations.
More information can be found at www.treosbio.com.
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