Phase I study with ONCOS-102 for the treatment of solid tumors - an evaluation of clinical response and exploratory analyses of immune markers

Background

We conducted a phase I study with a granulocyte macrophage colony stimulating factor (GMCSF)-expressing oncolytic adenovirus, ONCOS-102, in patients with solid tumors refractory to available treatments. The objectives of the study were to determine the optimal dose for further use and to assess the safety, tolerability and adverse event (AE) profile of ONCOS-102. Further, the response rate and overall survival were evaluated as well as preliminary evidence of disease control. As an exploratory endpoint, the effect of ONCOS 102 on biological correlates was examined.

Methods

The study was conducted using a classic 3 + 3 dose escalation study design involving 12 patients. Patients were repeatedly treated intratumorally with ONCOS-102 plus daily low-dose oral cyclophosphamide (CPO). Tumor response was evaluated with diagnostic positron emission tomography (PET) and computed tomography (CT). Tumor biopsies were collected at baseline and after treatment initiation for analysis of immunological correlates. Peripheral blood mononuclear cells (PBMCs) were collected at baseline and during the study to assess antigen specificity of CD8+ T cells by interferon gamma (IFNγ) enzyme linked immunospot assay (ELISPOT).

Results

No dose limiting toxicity (DLT) or maximum tolerated dose (MTD) was identified for ONCOS-102. Four out of ten (40 %) evaluable patients had disease control based on PET/CT scan at 3 months and median overall survival was 9.3 months. A short-term increase in systemic pro-inflammatory cytokines and a prominent infiltration of TILs to tumors was seen post-treatment in 11 out of 12 patients. Two patients showed marked infiltration of CD8+ T cells to tumors and concomitant systemic induction of tumor-specific CD8+ T cells. Interestingly, high expression levels of genes associated with activated T_H1 cells and T_H1 type immune profile were observed in the post-treatment biopsies of these two patients.

Conclusions

ONCOS-102 is safe and well tolerated at the tested doses. All three examined doses may be used in further development. There was evidence of antitumor immunity and signals of clinical efficacy. Importantly, treatment resulted in infiltration of CD8+ T cells to tumors and up-regulation of PD-L1, highlighting the potential of ONCOS-102 as an immunosensitizing agent for combinatory therapies with checkpoint inhibitors.

Trial registration

NCT01598129. Registered 19/04/2012

Abstract 2523: Strong synergistic effects with APR-246 and cisplatin in p53-mutant lung cancer cells

Background: Platinum compounds have been used as first-line treatment for many solid tumors including non small cell (NSCLC) and small cell (SCLC) lung cancer. However, patients with lung cancer often develop resistance to platinum compounds and eventually die of chemotherapy refractory disease. Mutation in the tumor suppressor protein p53 is common in lung cancer, ranging from 33% in adenocarcinomas to 70% in SCLC (The p53 website, http://p53.free.fr), and is one of the main causes for resistance to chemotherapy. APR-246 (PRIMA-1MET) is the first compound in clinical development that reactivates mutant p53 by inducing its wild type conformation thus triggering apoptosis (Lambert et al. Cancer Cell 15, 2009). APR-246 has yielded promising results in a first-in-human clinical trial in patients with hematological malignancies and prostate cancer (Lehmann et al. J Clin Oncol 30, 2012), and a Phase Ib/II study in combination with platinum-based therapy in ovarian cancer is ongoing. Previously we have shown strong synergy with APR-246 and platinum compounds in p53-mutant drug-resistant ovarian cancer cells (AACR abstract # 3448, 2013). Moreover, APR-246 completely restored the sensitivity of cisplatin to resistant p53-mutant ovarian cancer cells (AACR abstract #1801, 2014). The aim of the current study was to investigate whether strong synergistic effect can also be observed in p53-mutant lung cancer cells. Methods: Cell viability was determined with FMCA or Cell Titer-Glo assay, p53 gene status by Sanger sequencing and single strand conformation analysis, and p53 protein expression by Western blotting. Combination Index (CI) was calculated according to Additive model. Results: We observed strong synergistic effect (CI<0.5) with APR-246 and cisplatin in lung cancer cell lines carrying homozygous p53 hotspot mutations; NCI-H1770 (R248W), NCI-H1975 (R273H), NCI-H596 (G245C), PC-14 (R248W) and PC-14/CDDP (R248W). All these cell lines expressed a high level of p53. Synergistic (CI<0.8) or strong synergistic effect was found in lung cancer cell lines NCI-H378 (Y163C) and NCI-2087 (V157F) with homozygous mutations that occur frequently but are not hotspot mutations. NCI-2087 cells with the smoking-related V157F mutation express a high level of p53, while NCI-H378 cells express lower level. Mixed antagonist/additive/synergistic effects were observed in the p53 null cell line HOP-62, which does not express p53. Conclusions: Treatment with APR-246 in combination with cisplatin resulted in strong synergistic effect in both NSCL and SCLC cancer cells. Strongest synergies were observed in lung cancer cells with p53 hotspot mutations expressing a high level of p53. Studies to investigate the molecular mechanisms underlying the synergistic effects are ongoing. Our results suggest that combination treatment with APR-246 and platinum drugs may allow an improved therapy of p53-mutant lung cancer.

Citation Format: Nina Mohell, Åsa Fransson, Jessica Alfredsson, Mikael von Euler, Ulf Björklund, Lars Abrahmsen. Strong synergistic effects with APR-246 and cisplatin in p53-mutant lung cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2523. doi:10.1158/1538-7445.AM2015-2523

Abstract CT204: Preliminary results from PiSARRO, a phase Ib/II study of APR-246, a mutant p53 reactivating small molecule, in combination with standard chemotherapy in platinum-sensitive ovarian cancer

APR-246 (PRIMA-1MET) is the first clinical-stage compound that reactivates mutant p53. This phase Ib part of a proof of concept study aims to determine the recommended phase II dose (RP2D) of APR-246 in combination with carboplatin and pegylated liposomal doxorubicin (PLD) in platinum sensitive High Grade Serous Ovarian Cancer (HGSOC). Despite high response rates from carboplatin in combination with paclitaxel in first-line treatment of ovarian cancer, most patients relapse and develop resistance. Partially platinum sensitive patients relapse between 6 and 24 months and are commonly treated with second -line carboplatin and PLD (Pujade-Lauraine et al. JCO, 2010). The mechanisms of platinum resistance are multifactorial; two of the main causes are mutations in p53 and increased levels of intracellular glutathione. Like the analog PRIMA-1, APR-246 is a pro-drug that is converted to the active form MQ, which restores wild type conformation to mutant p53 (Lambert et al. Cancer Cell, 2009). In addition, APR-246 has been shown in vitro to reduce glutathione levels, resensitize cancer cells to platinum drugs, and induce ROS levels and ER stress (Mohell et al. Abstract #1801, AACR 2014; Lambert et al. Oncogene, 2010). In the first-in-human phase Ia study, APR-246 monotherapy was found to have a satisfactory safety and pharmacokinetic profile allowing it to be combined with full dose chemotherapy (Lehmann et al., JCO, 2012).

The ongoing phase Ib/II study is enrolling patients with recurrent platinum sensitive HGSOC with positive p53 staining on immunohistochemistry. The phase Ib study has a 3+3 dose escalation design with 3 planned dose levels. APR-246 is administered as a 6h i.v. infusion on 4 consecutive days every 4 weeks. On day 4, APR-246 is given concomitantly with carboplatin AUC 5 and PLD 30 mg/m2. In the phase II part, 164 patients will be randomized to standard chemotherapy with or without APR-246. To date patients have been enrolled to all 3 dose cohorts. One DLT of ruptured diverticulum occurred at the 2nd dose level. No new safety concerns have emerged. The pharmacokinetic profile has not indicated any interaction between APR-246 and the chemotherapy. The first 3 patients have completed their therapy and are now in follow up. All 3 had partial response (PR) by RECIST 1.1 and 2/2 evaluable also had PR by GCIC.

In conclusion, early results from the ongoing clinical study are encouraging and support the continued development of APR-246 in the phase II part of the study comparing platinum based standard chemotherapy with or without APR-246 in patients with HGSOC with mutant p53. Preliminary results from all three dose levels and the RP2D will be presented at the meeting.

Citation Format: Mikael von Euler, Klas G. Wiman, Hani Gabra, James D. Brenton, Bristi Basu, Ignace Vergote, Charlie Gourley, Austin Smith, Jessica Alfredsson, Nina Mohell, John A. Green. Preliminary results from PiSARRO, a phase Ib/II study of APR-246, a mutant p53 reactivating small molecule, in combination with standard chemotherapy in platinum-sensitive ovarian cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT204. doi:10.1158/1538-7445.AM2015-CT204

Local treatment of a pleural mesothelioma tumor with ONCOS-102 induces a systemic antitumor CD8+ T-cell response, prominent infiltration of CD8+ lymphocytes and Th1 type polarization

Late stage cancer is often associated with reduced immune recognition and a highly immunosuppressive tumor microenvironment. The presence of tumor infiltrating lymphocytes (TILs) and specific gene-signatures prior to treatment are linked to good prognosis, while the opposite is true for extensive immunosuppression. The use of adenoviruses as cancer vaccines is a form of active immunotherapy to initialise a tumor-specific immune response that targets the patient's unique tumor antigen repertoire. We report a case of a 68-year-old male with asbestos-related malignant pleural mesothelioma who was treated in a Phase I study with a granulocyte-macrophage colony‑stimulating factor (GM-CSF)-expressing oncolytic adenovirus, Ad5/3-D24-GMCSF (ONCOS-102). The treatment resulted in prominent infiltration of CD8⁺ lymphocytes to tumor, marked induction of systemic antitumor CD8⁺ T-cells and induction of Th1-type polarization in the tumor. These results indicate that ONCOS-102 treatment sensitizes tumors to other immunotherapies by inducing a T-cell positive phenotype to an initially T-cell negative tumor.

Abstract 1801: APR-246, a clinical-stage mutant p53-reactivating compound, resensitizes ovarian cancer cells to platinum compounds and doxorubicin

Background: Platinum-based drugs are since decades used as first-line treatment for many solid tumors. Patients with ovarian cancer often respond well to platinum compounds but a majority of patients rapidly develop resistance and die of chemotherapy refractory disease. The mechanisms underlying resistance are multifactorial, but two of the main causes are mutations in the tumor suppressor p53 and elevated intracellular glutathione (GSH) levels. Mutations in p53 occur in about 60% of ovarian tumors. APR-246 (PRIMA-1MET) is the first clinical-stage compound that reactivates mutant p53. APR-246 is a prodrug that accumulates in cancer cells and is converted to the active form MQ, a Michael acceptor that binds to mutant p53, refolds it to wild type conformation and triggers apoptosis (Lambert et al. Cancer Cell 15, 2009). APR-246 has been tested in a Phase I/IIa clinical trial with promising results (Lehmann et al. J Clin Oncol 30, 2012), and a Phase Ib/II study with platinum-based combination therapy in recurrent p53 mutant ovarian cancer is underway. Methods: Cell viability was assessed with WST-1, MTT or FMCA assay. p53 gene status was determined by Sanger sequencing and single strand conformation analysis, and p53 protein expression by Western blotting. Intracellular GSH levels were assessed with GSH kit (Cayman). Results: We have previously shown outstanding synergistic anticancer effects with APR-246 in combination with platinum compounds in p53 mutant solid cancer cell lines, including cisplatin resistant ovarian cancer cells. Synergistic effects were also observed ex vivo as well as in vivo in mice carrying human tumor xenografts. Here we show that APR-246 not only reactivates mutant p53 but also decreases intracellular GSH levels in a dose-dependent manner, presumably via adduct formation between MQ and GSH. APR-246 resensitized cisplatin resistant p53 mutant ovarian A2780-CP20 carcinoma cells to cisplatin, as shown by a decrease in the IC50 value from 52 to 2.9 µM, similar to the IC50 in parental A2780 cells. APR-246 also restored the sensitivity of resistant A2780ADR cells to doxorubicin. A2780-CP20 and A2780ADR were developed from the parental A2780 line with wild type p53 by chronic exposure to the respective drug. Moreover, APR-246 resensitized the p53 mutant OVCAR-3 cell line, established from a drug resistant patient, to cisplatin. Conclusions: Our results show that APR-246 not only reactivates mutant p53 but also decreases intracellular glutathione levels. We propose that this unique dual mechanism of action accounts for the resensitization and strong synergistic effects with APR-246 and platinum drugs. Our results provide strong rationale for the planned clinical study in ovarian cancer and suggest that combination treatment with APR-246 and DNA damaging drugs could have broad applicability in the treatment of drug resistant p53 mutant human tumors.

Citation Format: Nina Mohell, Jessica Alfredsson, Åsa Fransson, Vladimir Bykov, Mikael von Euler, Klas Wiman, Ulf Björklund. APR-246, a clinical-stage mutant p53-reactivating compound, resensitizes ovarian cancer cells to platinum compounds and doxorubicin. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1801. doi:10.1158/1538-7445.AM2014-1801

Single subcutaneous administration of chorionic gonadotropin to rats induces a rapid and transient increase in testicular expression of pro-inflammatory cytokines

hCG has been reported to cause an inflammation-like effect in the testis, although the background and consequences of this phenomenon remain to be understood. This investigation reveals that a single injection of hCG (100 U) induces a transient surge in pro-inflammatory cytokine expression in the adult rat testis. Reverse transcriptase PCR analysis demonstrated onset of testicular expression of IL-1beta and IL-6 mRNA and increases in the levels of mRNA encoding the constitutively expressed cytokines IL-1alpha, IL-1 receptor antagonist, and tumor necrosis factor-alpha 4 h after hCG injection and a maximal response after 8-12 h. These increases were accompanied by a transient increase in testicular IL-1 bioactive protein. Twenty-four hours after administration of hCG, the levels of all cytokine mRNA had decreased, although most were still elevated above control. Immunohistochemical staining revealed that the IL-1beta protein was undetectable in normal testes but was seen to be localized to interstitial macrophages but not Leydig cells after hCG treatment. Testes devoid of Leydig cells after pretreatment with ethane dimethane sulphonate exhibited normal staining for interstitial macrophages but failed to respond to hCG with increases in IL-1beta mRNA and protein expression. We conclude that hCG induces testicular inflammation via local activation by Leydig cells of the production of pro-inflammatory cytokines by resident macrophages. It remains to be investigated whether the high-dose hCG regimens used for treatment of boys with cryptorchidism could induce similar increases of pro-inflammatory cytokines in the human testis and if such treatments could adversely affect future testicular function.

[Molecule based diagnosis]

Based on reviews of the concept of diagnostics and in general and in specific tumour areas it was clear that development of diagnostic procedures involving genomics will allow for much better targeted and tailored treatments in the future. This will result in better efficacy and better tolerability of cancer treatments, but will also allow for progress in prediction, diagnosis and dose selection. Large collaborative projects studying the efficacy and safety of drugs on the genome level is promising to bring important benefits to both patients and the national economy by reducing useless drug therapy. In colorectal cancer there are several genetic defects identified that can act as the target for directed therapy in the future. Expressions of tumour specific antigens open the way for immunological targeted therapies. Developments in the understanding of the genomic basis for resistance to anti-tumour therapy is promising to help targeting patients likely to respond and not develop resistance. A Japanese model is being developed to determine the relative risk of breast cancer of Japanese women. Based on this prevention therapies can be instigated. The last four years have seen the introduction of four novel targeted therapies. If this model should become a standard in the future, much stronger collaboration between academic research and pharmaceutical industry need to develop.

[Globalization of clinical trials]

Based on reviews of the Japanese clinical trial situation in lung cancer, gastric cancer, prostate cancer and breast cancer, it was clear that much progress has been made in short time. There are considerable differences between Japan and the West and also differences between clinical areas in Japan. For regulatory purposes bridging studies have become increasingly important. Use of identical protocols are required for effective bridging. Participations in global phase III trials is the best way of achieving registration in Japan. For successful global trials in Japan it is important to include Japanese investigators in the preparation of the protocol and to recognise the challenges facing such a project. Clinical practice in diagnosis and treatment have many differences, thus it is recommended to have clear and detailed information in the protocol. Hard end points like survival are important since they are not biased by cultural differences. There are clear difficulties with HE or QOL outcomes. The emergence of focus on evidence based medicine is also happening in Japan and will help to harmonize documentation across the world. For large adjuvant or prevention cancer global trials are essential. To facilitate global studies further development of infrastructure is necessary in Japan. Use of electronic data capture web based communication etc. will help overcome communication difficulties. Other improvements that will make Japanese participation in global trials easier and better include establishment of clinical trial centre at each hospital, introduction of trial coordinators or study nurses and an improved collaboration with company staff. A critical issue that also need addressing is agreement of centre target recruitment. We need to introduce a new flexible system in Japan if participation in global trial is to be optimised. If we can address these issues Japanese investigators and collaborative groups should be able to initiate and lead global trials in the future.

[Post launch studies]

Evidence Based Medicine (EBM) is a growing concept in Japan as it is elsewhere. Central to improving the use of EBM is generation of data through well conducted controlled clinical studies. There are many problems associated with conduct of clinical studies after launch in Japan, and many initiatives are ongoing to improve the situation. Development of Clinical Research Coordinators (CRO) and central Data Management centers are key to improving the quality of clinical research in Japan. Currently Japan has an undeveloped legal system with regard to post-launch trials and off-label use of registered drugs. There is no reimbursement for off-label and various restrictions imposed on the recipients of the Ministry of Health, Labour and Welfare's (MHLW) funds. Maybe the biggest problem is the high cost of post-marketing studies sponsored by pharmaceutical manufacturers. A high quality system to support post launch clinical studies need a solid financial base. There is a need for a suitable review system for investigator initiated multi-centre studies, as the current IRB system is not sufficient. There are also challenges regarding the differences, perceived or real, in treatment practice and available registrations in Japan and in the West, causing problems in choosing suitable comparators and study designs. At the present time it is not clear whether investigator initiated trials will be acceptable for registration purposes in Japan. The agreed first priority is to build a suitable and strong infrastructure within the academic community to support researchers to investigate important questions with or without pharmaceutical company support. Despite all these issues, several groundbreaking projects are under way throughout Japan, in many different areas and by different collaborative groups, some with government support. In fact, researcher-initiated clinical trials achieved a rapid growth in Japan in the past year.