Galena Biopharma Presents GALE-302 Preliminary Immunologic Data Optimizing GALE-301 at the Society for Immunotherapy of Cancer (SITC) 30th Anniversary Annual Meeting

Galena Biopharma, Inc. GALE, a biopharmaceutical company developing and commercializing innovative, targeted oncology therapeutics that address major medical needs across the full spectrum of cancer care, today announced that data from the Company's GALE-301 and GALE-302 clinical programs were presented at the Society for Immunotherapy of Cancer (SITC) 30th Anniversary Annual Meeting in National Harbor, Maryland. The data presented was on the primary vaccine series (PVS) from a randomized Phase 1b trial with GALE-301 (E39) and GALE-302 (E39' -- variant of E39; previously named J65) that are folate binding protein-derived (FBP) peptides. Poster #166 (abstract #156) entitled, "Preliminary report of a clinical trial supporting the sequential use of an attenuated E39 peptide (E39') to optimize the immunologic response to the FBP (E39+GM-CSF) vaccine," details the results of a randomized trial comparing three PVS sequences of E39 and E39' in ovarian and breast cancer patients to optimize the ex vivo immune responses, local reactions (LR), and delayed type hypersensitivity (DTH) reactions. This preliminary analysis revealed both agents are immunogenic and well tolerated with no differences in toxicities between PVS sequences. The study demonstrates that the in vivo immune response is enhanced with the use of the attenuated E39' (GALE-302) after E39 (GALE-301). The optimal vaccination sequence utilizing three inoculations of GALE-301 followed by three inoculations of GALE-302 produced the most prominent and statistically significant LR and DTH responses. "We are pleased with the outcomes we observed in this trial as we evaluate strategies to optimize the immune response from our two clinical programs targeting folate binding protein," said Mark W. Schwartz, President and Chief Executive Officer. "Folate binding protein is a highly expressed tumor-associated antigen in many cancers making it a very logical treatment target for active immunotherapy. It also results in immunogenic peptides that have led to the development of a potentially very potent vaccine. It is theorized that this potency could lead to T-cell burn-out in patients over time, so we are assessing whether incorporating an attenuated version of the vaccine into the treatment regimen will provide a better immune response. The data derived from the DTH reactions indicate that treating patients first with the strong vaccine followed by a weaker version may provide a longer lasting effect. As the data continues to mature we will consider the outcomes as we plan the next stages for our GALE-301 and GALE-302 programs." The Phase 1b is a single-center, randomized, single-blinded, three-arm study in patients with breast (n=35) or ovarian cancer (n=4) diagnosis who have been treated by standard of care and are without evidence of disease. The primary endpoint of the trial is immunologic and designed to determine which of the three PVS strategies maximizes short and long-term specific immunity defined as the number of E39-specific CTLs one and six months, respectively following completion of the PVS. "The data presented confirms our assumption that sequencing the delivery of peptides provides varied immune responses and that the delivery can be optimized to potentially provide improved patient outcomes. Most importantly, we achieved a statistically significant increase in LR and DTH when delivering E39 followed by E39' in the PVS (p<0.001). We are currently implementing a booster program and continued analysis of immunologic responses will further elucidate the optimal vaccination series for the prevention of recurrence in breast and ovarian cancer," commented Doreen O. Jackson, M.D., post-doctoral fellow with the Cancer Vaccine Development Program and the San Antonio Military Medical Center, and the poster presenter. HLA-A2-positive breast or ovarian cancer patients were enrolled after completion of standard of care. The PVS includes six inoculations, one every 3-4 weeks containing 250mcg GM-CSF plus 500mcg peptide in the first five patients per arm and 250mcg GM-CSF + 1000mcg of peptide in the second five patients. Thirty-nine patients were randomized into three arms with 30 patients completing the PVS: -- E39 (GALE-301) x 6 inoculations (n=12) -- E39 (GALE-301) x 3 inoculations followed by E39' (GALE-302) x 3 inoculations (n=14) -- E39' (GALE-302) x 3 inoculations followed by E39 (GALE-301) x 3 inoculations (n=13) Ex vivo immune response was measured via dextramer assay for E39-specific CD8+ T-cells at pre-vaccine (R0), then 1 and 6-months after the PVS (RC1, RC6). To assess the in vivo immune response, LR was measured 48 hours after each inoculation, and DTH reactions were measured at R0, RC1, and RC6. Statistical analyses included descriptive statistics, 2-tailed t-test, Chi-squared, Fisher's exact test and ANOVA as appropriate. About GALE-301 and GALE-302 GALE-301 and GALE-302 are cancer immunotherapies that consist of a peptide derived from Folate Binding Protein (FBP) combined with the immune adjuvant, granulocyte macrophage-colony stimulating factor (GM-CSF) for the prevention of cancer recurrence in the adjuvant setting. GALE-301 is the E39 peptide, while GALE-302 is an attenuated version of this peptide, known as E39'. FBP is a well-validated therapeutic target that is highly over-expressed in ovarian, endometrial and breast cancers, and is the source of immunogenic peptides that can stimulate cytotoxic T lymphocytes (CTLs) to recognize and destroy FBP-expressing cancer cells. Two trials are ongoing with FBP peptides in gynecological cancers: the GALE-301 Phase 2a portion of the Phase 1/2a clinical trial is ongoing in ovarian and endometrial adenocarcinomas (ClinicalTrials.gov Identifier: NCT01580696); the GALE-301 plus GALE-302 Phase 1b clinical trial is ongoing in breast and ovarian cancers (ClinicalTrials.gov Identifier: NCT02019524).