Hershberg, Robert M.

Abstract Purpose: Somatic mosaic mutation in the PPM1D gene have been associated with risk of breast and ovarian cancer. Somatic mosaic mutations in blood cells may be associated with older age and chemotherapy exposure. We wanted to determine if somatic mosaic mutations in PPM1D and in other genes are associated with older age and repeated exposure to chemotherapy, rather than a contributor to risk of disease. Experimental design: We used targeted capture and massively parallel genomic sequencing to sequence DNA from PBMCs from affected patients for PPM1D as well as 60 other DNA repair genes. For a number of samples with PPM1D mutations, we re-sequenced at greater depth on patients where PBMCs that were collected at diagnosis and recurrence. Results: We identified somatic mosaic mutations in exon 6 of PPM1D in 4 out of 474 (0.8%) individuals that were newly diagnosed and had no previous chemotherapy, in 3 out of 29 (10%) individuals newly diagnosed but receiving chemotherapy and in 58 of 274 (21%) individuals with relapsed platinum resistant ovarian cancer (p<0.0001). The presence of PPM1D mutations in exon 6 was strongly associated with more advanced age (p=0.011, Wilcoxon test) and more than one chemotherapy regimen (p=0.026, Fisher's exact test). In paired blood samples from 13 patients, PPM1D mutations present at relapse were either not detected or detected at a lower percentage compared to blood obtained soon after diagnosis. Somatic mosaic mutations were also identified in TP53 in 7 of 274 (2.5%) women with relapsed platinum resistant cancer. In one of these cases, we had an earlier blood sample from diagnosis in which the mutation was not present at time near diagnosis. Conclusion: We found that somatic mosaic PPM1D mutations in PMBCs are associated with advanced age and repeated exposure to chemotherapy. Mosaic mutations in other genes were not confirmed with the exception of TP53, for which mutations are also detectable after extensive treatment. It seems likely that mosaic PPM1D mutations in blood from cancer patients may be a result of selection by chemotherapy of age-induced somatic mutations during exposure to chemotherapy. Further studies are needed to determine the clinical significance of these mutations. Citation Format: Maria I. Harrell, Barbara M. Norquist, Tom Walsh, Mark F. Brady, Ming K. Lee, Robert Hershberg, Kimberly R. Kalli, Heather Lankes, Eric Q. Konnick, Colin C. Pritchard, Bradley J. Monk, John K. Chan, Robert Burger, Scott H. Kaufmann, Michael J. Birrer, Elizabeth M. Swisher. Old age and chemotherapy contribute to the selection of PPM1D somatic mosaic mutations in ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr B71.

AbstractPurpose: Immunotherapy as a treatment for cancer holds the promise of complete and durable tumor remission, yet the immunosuppressive environment created by many tumors, advanced patient age, and previous treatments with cytotoxic agents may limit the approach. The activity of motolimod (VTX-2337), a potent and selective Toll-like receptor 8 (TLR8) agonist, was therefore assessed in the context of advanced, late-stage cancer patients.Experimental Design: The repertoire of mediators induced from human peripheral blood mononuclear cells in response to motolimod was characterized. Translational studies in cynomolgus monkeys elucidated the activity of motolimod on an intact immune system, identified biomarkers of TLR8 activation, and defined the relationship between the pharmacokinetic and pharmacodynamic (PK/PD) response. The PK/PD relationship for motolimod in cancer patients was assessed, compared with preclinical findings, and contrasted with activity in healthy volunteers.Results: In late-stage cancer patients, plasma levels of multiple biomarkers, including IL6, G-CSF, MCP-1, and MIP1-β, increased with increasing motolimod dose. The magnitude and breadth of the biomarker response closely aligned with the response seen in preclinical studies, demonstrating that advanced cancer patients remained responsive to TLR8 activation. In addition, the PK/PD response in cancer patients closely aligned with the activity of motolimod seen in healthy volunteers.Conclusions: Late-stage cancer patients are highly sensitive to TLR8 activation by motolimod. Tumor burden, advanced age, and prior treatment history with cytotoxic agents did not moderate or modify the response predicted by nonclinical studies and confirmed in healthy volunteers. Clin Cancer Res; 21(24); 5445–52. ©2015 AACR.

Abstract Immunotherapy has proven to be a successful treatment approach for some cancer patients. One promising paradigm in immunotherapy is targeting pathogen-associated molecule pattern receptors (PAMPS) such as the toll-like receptors (TLRs) to activate the innate immune system and enhance the development of tumor-directed adaptive immune responses. However, an ongoing concern in the application of immunotherapeutics is the potential for the immune response in cancer patients to be less robust than in healthy individuals, due to the underlying advanced neoplastic disease or due to previous regimens of cytotoxic drugs. To address this concern in relation to the response to TLR8 stimulation, we compared the pharmacokinetic and pharmacodynamic (PK/PD) relationship defined in a phase 1 clinical trial of the selective small molecule TLR8 agonist VTX-2337 in oncology patients to the response in healthy volunteers. A phase 1 dose-escalation clinical trial (A101) in subjects with advanced solid tumors (n=33) demonstrated that plasma levels of multiple biomarkers of immune activation, including G-CSF, MCP-1, MIP1-β and TNFα, increased in a dose-dependent manner and correlated with increasing plasma levels of VTX-2337. The PK/PD relationship defined in the initial clinical trial was closely aligned with predictions from both in vitro assays and preclinical studies conducted in cynomolgus monkeys. A subsequent phase 1 trial (A105) was conducted as a single-center, open-label, two-period, randomized, crossover, phase 1 study in normal volunteers (n=10). The objective of this study was to compare the PK/PD profiles and local tolerance of two formulations of VTX-2337. In this study, the two preparations of VTX-2337 demonstrated comparable PK profiles and PD responses. At comparable dose levels, the PK profile and overall exposure (AUC) to VTX-2337 was similar for oncology patients and healthy volunteers. VTX-2337 induced the same repertoire of circulating cytokines and chemokines, indicative of TLR8 activation, in both populations. The magnitude of the mediator response in oncology patients was also highly comparable to the response in healthy volunteers that received a similar dose. This comparison demonstrates that the immune system of cancer patients with advanced disease remains highly responsive to TLR8 activation by VTX-2337. In summary, advanced neoplastic disease or a prior treatment history with cytotoxic agents that can negatively impact immune cell function did not appear to moderate the response to VTX-2337 based on the PK/PD relationship using predictive biomarkers. Citation Format: Greg Dietsch, Donald Northfelt, Ramesh Ramanathan, Peter Cohen, Kristi Manjarrez, Mona Newkirk, James Kyle Bryan, Robert Hershberg. Immune modulation by the TLR8 agonist VTX-2337; a comparison of the pharmacodynamic response in cancer patients and healthy volunteers. [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 2540. doi:10.1158/1538-7445.AM2014-2540

Abstract Purpose: This phase I, open-label, uncontrolled, ascending-dose study explored the safety, maximum tolerated dose (MTD), pharmacokinetics, and pharmacology of the TLR8 agonist VTX-2337 in subjects with advanced solid tumors or lymphoma. Experimental Design: VTX-2337 doses (0.1–3.9 mg/m2) were administered subcutaneously on days 1, 8, and 15 of each 28-day cycle. Safety/tolerability assessments included adverse events (AE); physical, ophthalmologic, and laboratory evaluations; and electrocardiograms. Dose-limiting toxicities (DLT) were evaluated during the first cycle. Pharmacokinetics were evaluated after the first dose. Plasma samples were quantitatively assessed for chemokines, cytokines, and other inflammatory mediators. Antitumor activity was assessed. Results: Thirty-three subjects were enrolled in 8 cohorts and received an average of 2 treatment cycles (range, 1–8 cycles). Most AEs were grades 1 to 2; the most common drug-related AEs were injection site reactions, chills, pyrexia, and influenza-like illness. One DLT was reported: grade 3 hypotension (3.9 mg/m2). The MTD was considered the highest dose administered. Peak drug plasma levels and total systemic exposure were generally dose proportional. At doses ≥0.4 mg/m2, increases above baseline levels were observed for plasma levels of G-CSF, monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, and TNFα. Eight subjects (24.2%) had a best response of stable disease (median duration, 54.5 days). Conclusions: VTX-2337 is clinically well tolerated and biologically active with a predictable pharmacokinetic profile. Suitable doses for testing in combination studies were identified. Phase II placebo-controlled studies of VTX-2337 in combination with doxorubicin in ovarian cancer, and in combination with platinum chemotherapy, 5 FU, and cetuximab in head and neck cancer have been initiated (NCT #01666444 and NCT#01836029). Clin Cancer Res; 20(14); 3683–91. ©2014 AACR.