Targovax's ONCOS-102 Mesothelioma 12-month Data Powerfully Demonstrate Broad Immune Activation Linked to Clinical Benefit

• Encouraging PFS and survival data in ONCOS-102-treated first line patients as 31 patients have now completed 12 months follow-up
• Mechanistic evidence of profound immune activation in ONCOS-102-treated patients associated with better clinical outcomes
• Immune activation data provides clear scientific rationale for anti-PD1/L1 checkpoint inhibitor combination in upcoming trial in first line mesothelioma

OSLO, Norway, June 22, 2020 /PRNewswire/ -- Targovax ASA (OSE: TRVX), a clinical stage immuno-oncology company developing oncolytic viruses to target hard-to-treat solid tumors, today releases 12-month efficacy and immunological data from the randomized phase I/II trial of ONCOS-102 in combination with standard of care chemotherapy in malignant pleural mesothelioma (MPM).

The trial is an open label, exploratory phase I/II trial adding ONCOS-102 to standard of care (SoC) chemotherapy (pemetrexed/cisplatin) in first and second (and later) line MPM to assess safety, immune activation and clinical efficacy vs SoC only. In total, 31 patients have been treated in the trial, with 20 patients in the experimental group receiving the ONCOS-102 and SoC combination, and 11 patients in a control group receiving SoC only. The 31 patients have now completed the 12-month follow-up. The first set of data was reported in January 2020, see press release here, with an update in May 2020, see press release here.

The median Progression Free Survival (mPFS) for ONCOS-102 treated first line patients remains at 8.9 months, which is identical to the previously reported early data. mPFS for the control group first line patients treated with SoC chemotherapy only is 7.6 months. The first line mPFS data continues to compare favorably to SoC historical controls, which have shown mPFS of 5.7-7.3 months^[1]. As there is now longer follow-up and few censored patients left in the PFS analysis, the updated figures can be considered close to final.

The 12-month survival rate was 64% in the first line ONCOS-102 treated patients, compared to 50% in the first line control group treated with SoC chemotherapy only (median Overall Survival is too early to report). The patients continue to be followed and updated Overall Survival (OS) figures will be published as they mature. This 64% 12-month survival rate is encouraging compared to the control group, but there are few historical control reference points. Recently, at ASCO 2020, results from a first line mesothelioma trial assessing SoC chemotherapy in combination with the anti-PD-L1 checkpoint inhibitor durvalumab showed a 70% 12-month survival rate. This suggests that ONCOS-102 alone plus SoC chemotherapy may already achieve a level of benefit close to that observed with checkpoint inhibition plus SoC chemotherapy. It is expected that addition of checkpoint inhibition to ONCOS-102 and Soc will provide even further clinical benefit due to engagement of distinct and complementary biological mechanisms. As such, Targovax's future clinical development of ONCOS-102 will focus on first line mesothelioma with the triple combination of a checkpoint inhibitor, ONCOS-102 and SoC. A randomized phase II trial is currently being planned in collaboration with a pharma partner.

Tumor biopsy immunohistochemistry and gene expression analyses from the present trial confirm the predicted mode of action of ONCOS-102. Importantly, profound innate and adaptive immune activation is observed in the ONCOS-102 treated patients compared to the control group, and this immune activation is associated with better clinical outcome. The immune activation is hallmarked by an increase in intra-tumoral cytotoxic T-cells and upregulation of adaptive immunity and cytotoxicity related gene expression, in parallel with polarization from M2 to M1 macrophage phenotype and upregulation of PD-L1 expression, indicating that ONCOS-102 is driving a favorable remodeling of the tumor microenvironment. This powerfully demonstrates the immune activation potential of ONCOS-102 far beyond what is achieved by chemotherapy alone and suggests that patients may be effectively sensitized to treatment with an anti-PD1/L1 antagonist, thereby providing strong scientific rationale for the combination of ONCOS-102 and checkpoint inhibition in first line mesothelioma.

Dr. Magnus Jäderberg, Chief Medical Officer of Targovax, said: "We are very pleased to see the encouraging first line PFS data holding up in the 12-month analysis, with early signs of positive survival outcomes. We are particularly excited to observe a broad and profound immune activation in the ONCOS-102 treated patients, which confirms the proposed mode of action. ONCOS-102 treatment clearly drives a favorable remodeling of the tumor microenvironment, and this remodeling is linked to better clinical outcomes. This immune activated tumor micro-environment provides the key scientific rationale and an ideal backdrop for combination treatment with a checkpoint inhibitor. These data set us up perfectly to move forward with a trial combining ONCOS-102 and a checkpoint inhibitor, which we believe will release the full potential of immunotherapy in this hard-to-treat patient population".

For a video presentation of the data, please see links below:

• English version Magnus Jäderberg, Chief Medical Officer
• Norwegian version Erik Digman Wiklund, Cheif Business Officer

^[1] Vogelzang 2003, Ceresoli 2006, Zalcman 2015, Tsao 2019, Scagliotti 2019

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