Dendritic cell-based vaccines: Shining the spotlight on signal 3

Dendritic cell (DC)-based anticancer vaccines have yielded disappointing results in a multitude of clinical trials. New data suggest that the clinical efficacy of DC-based vaccines may be dependent on the paracrine production of interleukin-12 in the course of antigen presentation and the consequent development of therapeutic Type 1 CD8(+) T-cell immunity

pVAC-Seq: A genome-guided in silico approach to identifying tumor neoantigens

Cancer immunotherapy has gained significant momentum from recent clinical successes of checkpoint blockade inhibition. Massively parallel sequence analysis suggests a connection between mutational load and response to this class of therapy. Methods to identify which tumor-specific mutant peptides (neoantigens) can elicit anti-tumor T cell immunity are needed to improve predictions of checkpoint therapy response and to identify targets for vaccines and adoptive T cell therapies. Here, we present a flexible, streamlined computational workflow for identification of personalized Variant Antigens by Cancer Sequencing (pVAC-Seq) that integrates tumor mutation and expression data (DNA- and RNA-Seq). pVAC-Seq is available a

Preclinical evaluation of cancer immune therapy using patient-derived tumor antigen-specific T cells in a novel xenograft platform.

Objectives: With a rapidly growing list of candidate immune-based cancer therapeutics, there is a critical need to generate highly reliable animal models to preclinically evaluate the efficacy of emerging immune-based therapies, facilitating successful clinical translation. Our aim was to design and validate a novel Methods: Tumor xenografts are established rapidly in the greater omentum of globally immunodeficient NOD- Results: The tumors progress rapidly and disseminate in the mice unless patient-derived tumor-specific T cells are introduced. An initial T cell-mediated tumor arrest is later followed by a tumor escape, which correlates with the upregulation of the checkpoint molecules programmed cell death-1 (PD-1) and lymphocyte-activation gene 3 (LAG3) on T cells. Treatment with immune-based therapies that target these checkpoints, such as anti-PD-1 antibody (nivolumab) or interleukin-12 (IL-12), prevented or delayed the tumor escape. Furthermore, IL-12 treatment suppressed PD-1 and LAG3 upregulation on T cells. Conclusion: Together, these results validate the X-mouse model and establish its potential to preclinically evaluate the therapeutic efficacy of immune-based therapies

Early objective response to avelumab treatment is associated with improved overall survival in patients with metastatic Merkel cell carcinoma

Background: Response rates are primary endpoints in many oncology trials; however, correlation with overall survival (OS) is not uniform across cancer types, treatments, or lines of therapy. This study explored the association between objective response (OR) and OS in patients with chemotherapy-refractory metastatic Merkel cell carcinoma who received avelumab (anti-PD-L1). Methods: Eighty-eight patients enrolled in JAVELIN Merkel 200 (part A; NCT02155647) received i.v. avelumab 10 mg/kg every 2 weeks until confirmed progression, unacceptable toxicity, or withdrawal. Using conditional landmark analyses, we compared OS in patients with and without confirmed OR (RECIST v1.1). We applied a Cox model that included OR as a time-varying covariate and adjusted for age, visceral disease, and number of previous therapies. Results: Twenty-nine patients had confirmed OR; 20 by study week 7 and 7 more between study weeks 7 and 13. Survival probabilities 18 months after treatment initiation were 90% [95% confidence interval (CI) 65.6-97.4] in patients with OR at week 7 and 26.2% (95% CI 15.7-37.8) in patients without OR but who were alive at week 7. Median OS was not reached in patients with OR and was 8.8 months (95% CI 6.4-12.9) in patients without. Similar results were observed for the week 13 landmark. The adjusted Cox model showed OR was associated with a 95% risk reduction of death [hazard ratio 0.052 (95% CI 0.018-0.152)] compared with a nonresponse. Conclusions: Patients with OR by 7 or 13 weeks had significantly longer OS than patients without, confirming that early OR is an endpoint of major importance

IL-12p70–producing patient DC vaccine elicits Tc1-polarized immunity

Background. Systemic administration of IL-12p70 has demonstrated clinical activity in cancer patients, but dose-limiting toxicities have hindered its incorporation in vaccine formulations. Here, we report on the immunological and clinical outcomes upon vaccination with CD40L/IFN-γ–matured, IL-12p70–producing DCs. Methods. 7 HLA-A*0201(+) newly diagnosed stage IV melanoma patients were immunized against the gp100 melanoma antigen using autologous peptide-pulsed, CD40L/IFN-γ–matured DCs. PBMCs were taken weekly for immune monitoring by tetramer analysis and functional assays. CT imaging was performed at baseline, week 9, and week 18 for clinical assessment using RECIST. Results. 6 of 7 treated patients developed sustained T cell immunity to all 3 melanoma gp100 antigen–derived peptides. 3 of the 6 immunological responders developed confirmed clinical responses (1 complete remission >4 years, 2 partial response). Importantly, DC vaccine–derived IL-12p70 levels positively correlated with time to progression (P = 0.019, log-rank), as did T-cytotoxic 1 (Tc1) immunity, as assessed by IFN-γ/IL-13 and IFN-γ/IL-5 ratios (P = 0.035 and P = 0.030, respectively, log-rank). In contrast, a pathway-specific defect in IL-12p35 transcription was identified upon CD40L/IFN-γ activation in clinical nonresponder patient DCs, and gp100-specific T cells from these patients displayed a Tc2 phenotype. Incorporation of TLR3 and TLR8 agonists into the CD40L/IFN-γ activation protocol corrected the IL-12p70 production defect in DCs derived from clinical nonresponder patients. Conclusion. These findings underscore the essential role of IL-12p70 in the development of therapeutic type 1 antigen–specific CD8(+) T cell immunity in humans with cancer. Trial registration. Clinicaltrials.gov NCT00683670. Funding. Barnes-Jewish Hospital Foundation, Siteman Cancer Frontier Fund, Washington University/JNJ Translational Medicine Award, and NCI (P30 CA91842)

Noninvasive Determination of Melanoma Depth using a Handheld Photoacoustic Probe

In this work, we propose applying photoacoustic tomography (PAT) to address this problem. Compared with traditional optical imaging methods, PAT uses ultrasonic waves, which give approximately 1,000 times less scattering than optical waves, breaking through the optical diffusion limit (∼1 mm in the skin) for penetration (Wang and Hu, 2012; Wang and Gao, 2014). In addition, by using optical excitation of acoustic waves due to light absorption, PAT provides improved contrast of melanin, which is deficient in ultrasonographic imaging. In previous mouse models, we measured a melanoma greater than 7 mm in depth (Zhou et al., 2015). Here we extend our work to patients with melanoma, with the aim of determining the accuracy of PAT-measured melanoma depth compared with the actual BD based on excisional biopsy results. In addition, we also compare our PAT measurement with the histologic measurement obtained from partial incisional biopsy to ultimately determine the predictability and application of PAT measurements in a clinical setting

Noninvasive Determination of Melanoma Depth using a Handheld Photoacoustic Probe

In this work, we propose applying photoacoustic tomography (PAT) to address this problem. Compared with traditional optical imaging methods, PAT uses ultrasonic waves, which give approximately 1,000 times less scattering than optical waves, breaking through the optical diffusion limit (∼1 mm in the skin) for penetration (Wang and Hu, 2012; Wang and Gao, 2014). In addition, by using optical excitation of acoustic waves due to light absorption, PAT provides improved contrast of melanin, which is deficient in ultrasonographic imaging. In previous mouse models, we measured a melanoma greater than 7 mm in depth (Zhou et al., 2015). Here we extend our work to patients with melanoma, with the aim of determining the accuracy of PAT-measured melanoma depth compared with the actual BD based on excisional biopsy results. In addition, we also compare our PAT measurement with the histologic measurement obtained from partial incisional biopsy to ultimately determine the predictability and application of PAT measurements in a clinical setting

Phase II study of the farnesyltransferase inhibitor R115777 in advanced melanoma (CALGB 500104)

BACKGROUND: Multiple farnesylated proteins are involved in signal transduction in cancer. Farnesyltransferase inhibitors (FTIs) have been developed as a strategy to inhibit the function of these proteins. As FTIs inhibit proliferation of melanoma cell lines, we undertook a study to assess the impact of a FTI in advanced melanoma. As farnesylated proteins are also important for T cell activation, measurement of effects on T cell function was also pursued. METHODS: A 3-stage trial design was developed with a maximum of 40 patients and early stopping if there were no responders in the first 14, or fewer than 2 responders in the first 28 patients. Eligibility included performance status of 0–1, no prior chemotherapy, at most 1 prior immunotherapy, no brain metastases, and presence of at least 2 cutaneous lesions amenable to biopsy. R115777 was administered twice per day for 21 days of a 28-day cycle. Patients were evaluated every 2 cycles by RECIST. Blood and tumor were analyzed pre-treatment and during week 7. RESULTS: Fourteen patients were enrolled. Two patients had grade 3 toxicities, which included myelosuppression, nausea/vomiting, elevated BUN, and anorexia. There were no clinical responses. All patients analyzed showed potent inhibition of FT activity (85-98%) in tumor tissue; inhibition of phosphorylated ERK and Akt was also observed. T cells showed evidence of FT inhibition and diminished IFN-γ production. CONCLUSIONS: Despite potent target inhibition, R115777 showed no evidence of clinical activity in this cohort of melanoma patients. Inhibition of T cell function by FTIs has potential clinical implications. Clinicaltrials.gov number NCT0006012

A case of recurrent bilateral uveitis independently associated with dabrafenib and pembrolizumab therapy

Purpose: To report the case of an adult female who presented on different occasions with recurrent uveitis provoked by initiating therapy of two recently approved agents, dabrafenib and pembrolizumab, for treatment of metastatic melanoma. Observations: A 61 year old female presented with bilateral anterior uveitis after initiating therapy with dabrafenib for advanced metastatic melanoma. Her symptoms resolved and exam improved with oral and topical steroid therapy. Months later, she was started on pembrolizumab and transitioned off dabrafenib. Within days of starting pembrolizumab, she developed recurrent bilateral uveitis. This responded to escalating doses of topical and oral corticosteroid therapy and resolved following discontinuation of pembrolizumab. Nine months later, our patient received her third dose of pembrolizumab due to further progression of melanoma and within three days developed blurry vision, photophobia and subsequent ophthalmologic exam demonstrated bilateral panuveitis. Conclusions and importance: Dabrafenib and pembrolizumab therapy have both previously been associated with uveitis. Here, we document a case of a woman who developed acute uveitis in response to beginning therapy with dabrafenib and then later developed acute uveitis soon after initiating pembrolizumab. To our knowledge, this is the first time this uncommon side-effect has been reported in the same patient after receiving sequential targeted agents and checkpoint inhibitors