Academic literature on the topic 'Plasmacytoid dendritic cell, metastatic melanoma'

The introduction of targeted therapies and immunotherapies has significantly improved the outcome of metastatic melanoma (MM) patients. These approaches rely on immune functions for their anti-melanoma response. Plasmacytoid dendritic cells (pDCs) exhibit anti-tumor function by production of effector molecules, type I interferons (I-IFNs), and cytokines. Tissue and blood pDCs result compromised in MM, although these findings are still partially conflicting. This study reports that blood pDCs were dramatically depleted in MM, particularly in patients with high lactate dehydrogenase (LDH) and high tumor burden; the reduced pDC frequency was associated with poor overall survival. Circulating pDCs resulted also in significant impairment in interferon alpha (IFN-α) and C-X-C motif chemokine 10 (CXCL10) production in response to toll-like receptor (TLR)-7/8 agonists; on the contrary, the response to TLR-9 agonist remained intact. In the BRAFV600+ subgroup, no recovery of pDC frequency could be obtained by BRAF and MEK inhibitors (BRAFi; MEKi), whereas their function was partially rescued. Mechanistically, in vitro exposure to lactic acidosis impaired both pDC viability and function. In conclusion, pDCs from MM patients were found to be severely impaired, with a potential role for lactic acidosis. Short-term responses to treatments were not associated with pDC recovery, suggesting long-lasting effects on their compartment.

The prognosis of metastatic melanoma (MM) patients has remained poor for a long time. However, the recent introduction of effective target therapies (BRAF and MEK inhibitors for BRAFV600-mutated MM) and immunotherapies (anti-CTLA-4 and anti-PD-1) has significantly improved the survival of MM patients. Notably, all these responses are highly dependent on the fitness of the host immune system, including the innate compartment. Among immune cells involved in cancer immunity, properly activated plasmacytoid dendritic cells (pDCs) exert an important role, bridging the innate and adaptive immune responses and directly eliminating cancer cells. A distinctive feature of pDCs is the production of high amount of type I Interferon (I-IFN), through the Toll-like receptor (TLR) 7 and 9 signaling pathway activation. However, published data indicate that melanoma-associated escape mechanisms are in place to hijack pDC functions. We have recently reported that pDC recruitment is recurrent in the early phases of melanoma, but the entire pDC compartment collapses over melanoma progression. Here, we summarize recent advances on pDC biology and function within the context of melanoma immunity.

Purpose The recent identification of toll-like receptors (TLRs) and respective ligands allows the evaluation of novel dendritic cell (DC) –activating strategies. Stimulation of TLR9 directly activates human plasmacytoid DCs (PDCs) and indirectly induces potent innate immune responses in preclinical tumor models. We performed an open-label, multicenter, single-arm, phase II pilot trial with a TLR9-stimulating oligodeoxynucleotide in melanoma patients. Patients and Methods Patients with unresectable stage IIIb/c or stage IV melanoma received 6 mg PF-3512676 weekly by subcutaneous injection for 24 weeks or until disease progression to evaluate safety as well as clinical and immunologic activity. Clinical and laboratory safety assessments were performed weekly; blood samples for immunological measurements were taken every 8 weeks. Tumor measurements were performed according to Response Evaluation Criteria in Solid Tumors. Results Twenty patients received PF-3512676 for a mean of 10.9 weeks with a mean of 10.7 injections. Laboratory and nonlaboratory adverse events were limited, transient, and did not result in any withdrawals. Two patients experienced a confirmed partial response; one response is ongoing for 140+ weeks. Three patients experienced stable disease. Immunologic measurements revealed induction of an activated phenotype of PDC, elevation of serum levels of 2′,5′-oligoadenylate, a surrogate marker of type I interferon production, and significant stimulation of natural killer cell cytotoxicity (the latter was associated with clinical benefit). Conclusion These results indicate that TLR9-targeted therapy can stimulate innate immune responses in cancer patients, identify biomarkers that may be associated with TLR9-induced tumor regression, and encourage the design of follow-up studies to evaluate the ability of this therapeutic approach to target human cancer.

9582 Background: Toll like receptor (TLR) agonists may enhance vaccination or direct immune activation at the tumor microenvironment. This trial evaluates the biologic and clinical effects of Resiquimod, a TLR 7/8 agonist that can activate both myeloid (mDC, TLR 8) and plasmacytoid (pDC, TLR 7) dendritic cells, in patients with advanced stage melanoma. Methods: Class I HLA-A0201+ subjects with in-transit melanoma metastases or high risk for recurrence were vaccinated weekly with peptide vaccination (class I restricted peptide GP100209-2m and, if HLA-DP4+, also with class II restricted peptide MAGE-3243-258). Subjects were randomized 1:1 to receive Resiquimod as an adjuvant applied to the GP100 vaccination site. Subjects with in-transit disease were thereafter treated with resiquimod topically on half of the target lesions. Results: All patients (n = 47) underwent GP100209-2m vaccination, a majority (39) also received the MAGE-3243-258 peptide. The type I interferon-inducible genes (Mx A and IRF7), IFNg, and IP-10 RNA expression were up-regulated only in vaccination sites treated with Resiquimod (each p < 0.01) , demonstrating pDC activation (Type I interferon) and possibly T and NK cell activation (IFNg and IP-10). Nineteen subjects had in-transit disease at entry into the trial. In response to peptide vaccination alone, tumor regression was more likely in patients who received Resiquimod at the vaccination site (group A) compared to those who did not (group B). (4/9 vs 0/10, p = 0.033). In group A, 5 patients continued treatment with Resiquimod topically on the tumors, and all had tumor response (4PR, 1CR). In group B, 5 continued to tumoral resiquimod and 3 had regression (3 PR). Conclusions: Resiquimod increases Type I interferon and IFNg at the peptide vaccination site by activation of pDC/mDC and increases the antitumor response sufficiently to mediate regression of in-transit melanoma metastasis. Resiquimod on in-transit melanoma, in vaccinated hosts, drives regression of metastases, regardless of previous exposure at vaccination. Clinical trial information: NCT00960752.

10563 Background: Overall, the clinical efficacy of tumor immunotherapy has been limited. Our incomplete understanding of the complex interplay between tumors and the immune microenvironment has contributed to these modest outcomes. Our work has revealed that several tumors downregulate the expression of the type III TGFβ receptor (TβRIII) with progression. TβRIII is shed from the cell surface to generate soluble TβRIII (sTβRIII) which is capable of sequestering TGFβ. Methods and Results: Using both breast cancer and melanoma tumor models we have demonstrated that the loss of TβRIII expression is associated with diminished tumor infiltrating CD8+ T cells and increased regulatory T cells (Tregs) within the tumor microenvironment. Our data implies that these alterations correlate with suppressed tumor antigen-specific T cell responses and more rapid disease progression. We show that these changes are due to enhanced TGFβ signaling within the immune compartment of the tumor microenvironment resulting in enhanced expression of the indoleamine 2,3-dioxygenase immunoregulatory enzyme by local plasmacytoid dendritic cells (DCs) as well as increased expression of the Treg-recruiting CCL22 chemokine by local myeloid DCs. Microarray analysis indicates that these same gene expression associations also exist in human breast cancers. Consistent with these studies, we have demonstrated that TGF-β inhibition synergistically enhances the efficacy of a Her2/neu vaccine in a breast cancer model and that plasma levels of sTβRIII correlate with clinical response and overall survival in stage III melanoma patients. Conclusions: We have elucidated a novel mechanism that tumors utilize to suppress the generation of anti-tumor immunity by establishing a link between the loss of an endogenous suppressor of tumor metastasis, TβRIII, and the generation of an immunotolerant tumor microenvironment. We are pursuing a phase I clinical trial to investigate the efficacy of combining a TGF-β inhibitor with a tumor vaccine while also determining if sTβRIII may function as a predictive biomarker for this approach.

TPS6089 Background: PD-1 blockade ± chemotherapy has recently become a primary systemic therapy recommended by NCCN guidelines for patients (pts) with recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC). However, most pts still do not respond to treatment, indicating a large unmet need for pts with unresectable disease. CMP-001 is a toll-like receptor 9 (TLR9) agonist comprising a CpG-A oligodeoxynucleotide packaged in a virus-like particle that can induce type I interferon secretion from tumor-associated plasmacytoid dendritic cells, promoting a Th1-like chemokine milieu in the tumor microenvironment and inducing an antitumor CD8+ T-cell response. In a phase (ph) 1b study in pts with metastatic melanoma, intratumoral (IT) injection of CMP-001 + intravenous (IV) pembrolizumab (pembro) reversed PD-1 blockade resistance, induced responses in injected and noninjected lesions, and had an acceptable safety profile (Milhem et al, SITC 2020). This combination is therefore being tested in pts with HNSCC. Methods: CMP-001-007 (NCT04633278) is an open-label, multicenter, ph 2 study designed to investigate the efficacy and safety of CMP-001 + IV pembro in adult pts with histologically or cytologically confirmed R/M HNSCC considered incurable by local therapies. Eligible pts have undergone a pretreatment tumor biopsy, received no prior systemic therapy in the R/M setting, and have primary tumor locations of oropharynx, oral cavity, hypopharynx, or larynx. In addition, pts must have PD-L1-positive tumors (combined positive score ≥1), known tumor human papillomavirus (HPV) status (for oropharyngeal cancer), and measurable disease per RECIST v1.1 with ≥1 lesion amenable to IT injection. Pts with primary tumors in the nasopharynx are excluded. Enrolled pts will receive CMP-001 10 mg once weekly for 7 doses and every 3 weeks (Q3W) thereafter. The first dose may be administered subcutaneously or via IT injection, with all subsequent doses administered IT. All pts will also receive pembro 200 mg IV Q3W after the CMP-001 injection. Treatment continues until unacceptable toxicity or disease progression. The primary endpoint is investigator-assessed objective response rate (ORR) per RECIST v1.1. Secondary endpoints include safety, duration of response (DOR), progression-free survival (PFS), overall survival, and effects of HPV infection and PD-L1 expression on ORR, DOR, and PFS. Exploratory endpoints include analyses of baseline and changes from baseline in tumor or serum biomarkers related to TLR9, immune checkpoints, and potential predictors of response, as well as serum concentrations of CXCL10 and CMP-001. Refer to clinicaltrials.gov/ct2/show/NCT04633278 for the most current information on enrolling sites. Clinical trial information: NCT04633278.

BackgroundNeoadjuvant PD-1 blockade produces major pathological responses (MPR) in ~30% of patients (pts) with high-risk resectable melanoma (MEL) with durable relapse-free benefit, and increased circulating activated CD8+ T cells.1 2 CMP-001 is a type A CpG packaged within a virus-like particle that activates tumor-associated plasmacytoid dendritic cells (pDC) via TLR9 inducing type I interferons and anti-tumor CD8+ T cells. CMP-001/pembrolizumab produces durable anti-tumor responses in PD-1 refractory melanoma.3 We previously reported preliminary evidence of efficacy of neoadjuvant IT CMP/Nivo in high-risk resectable MEL; and herein present final results on 30 evaluable patients.Methods30 pts with stage III B/C/D MEL were enrolled. Pre-operatively, CMP-001 was dosed at 5 mg subcutaneous (SC, 1st), then 10 mg IT (2nd-7th) weekly; Nivo was dosed 240 mg q2 weeks for 3 doses – both agents given for 7 weeks. Post-operatively, Nivo was dosed 480 mg q4 weeks with CMP-001 5 mg q4 weeks SC for 48 weeks. Primary endpoints included major pathologic response rate (MPR), and incidence of dose-limiting toxicities (DLT). Secondary endpoints were radiographic response, relapse-free survival (RFS) and overall survival (OS). Pathological response was scored blinded by pathologists based on residual volume of tumor (RVT) using prior specified cutoffs:4 60% (complete response, pCR); 0%<rvt<rvt50% (non-response, pNR). Radiographic response was assessed using RECIST v1.1. Sequential blood draws and tumor biopsies were collected and analyzed for CD8+ T cell infiltrate (TIL), multiparameter flow cytometry (MFC) and multiplex immunofluorescence (mIF).Results30 pts with regionally advanced MEL were enrolled, of stages IIIB (57%), IIIC (37%), IIID (7%). 29/30 (97%) of pts completed 7 weeks of neoadjuvant Nivo/CMP; while 1 pt had a delay in surgery related to a pre-operative infection unrelated to therapy. No DLTs were reported; grade 3/4 irAE were reported in 3 pts (11%) leading to CMP-001 discontinuation in 2 pts (7%). Radiographic responses were seen in 13 pts (43%), while 9 pts (30%) had stable disease and 8 pts (27%) had progressive disease. Pathological responses (RVT <50%) were seen in 70% of pts: pCR 15 (50%), pMR 3 (10%), 3 pPR (10%); only 9 (30%) had pNR. Pathological responders (pCR/pMR) had increased CD8+ TIL and CD303+ pDC intra-tumorally by mIF; and peripherally activated PD1+/Ki67+ CD8+ T cells by MFC.ConclusionsNeoadjuvant CMP/Nivo has acceptable toxicity and promising efficacy. MPR is 60% in 30 pts. 1-year RFS was 82% (all pts) and 89% (among those with pCR/pMR); median RFS is 9 months (among pNR/pPR) and not reached (among pCR/pMR). Response is associated with evidence of immune activation intra-tumorally and peripherally. IT CMP001 increases clinical efficacy of PD-1 blockade with minimal additional toxicity in pts with regionally advanced MEL. Further study of this combination in high-risk resectable MEL is planned.AcknowledgementsWe thank Dr. Jagjit Singh and the pathology grossing room staff for their assistance and Checkmate Pharmaceuticals for funding and CMP-001.Trial RegistrationClinical trial information: NCT03618641Ethics ApprovalThe study was approved by University of Pittsburgh’s Institutional Review Board, approval number MOD19040237-002.ConsentWritten informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.ReferencesAmaria RN, Reddy SM, Tawbi HA, et al. Neoadjuvant immune checkpoint blockade in high-risk resectable melanoma. Nat Med 2018. Nov;24(11):1649–1654.Huang AC, Orlowski RJ, Xu X, et al. A single dose of neoadjuvant PD-1 blockade predicts clinical outcomes in resectable melanoma. Nat Med 2019. Mar;25(3):454–461. doi: 10.1038/s41591-019-0357-y.Milhem M, Gonzales R, Medina T, et al. Abstract CT144: Intratumoral toll-like receptor 9 (TLR9) agonist, CMP-001, in combination with pembrolizumab can reverse resistance to PD-1 inhibition in a phase Ib trial in subjects with advanced melanoma. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14–18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract CT144.Tetzlaff MT, Messina JL, Stein JE, et al. Pathological assessment of resection specimens after neoadjuvant therapy for metastatic melanoma. Ann Oncol 2018. Aug 1;29(8):1861–1868.Cottrell TR, Thompson ED, Forde PM, et al. Pathologic features of response to neoadjuvant anti-PD-1 in resected non-small-cell lung carcinoma: a proposal for quantitative immune-related pathologic response criteria (irPRC). Ann Oncol 2018 Aug 1;29(8):1853–1860. doi: 10.1093/annonc/mdy218.Stein JE, Soni A, Danilova L, et al. Major pathologic response on biopsy (MPRbx) in patients with advanced melanoma treated with anti-PD-1: evidence for an early, on-therapy biomarker of response. Ann Oncol 2019 Apr 1;30(4):589–596. doi: 10.1093/annonc/mdz019.

Le cellule dendritiche plasmacitoidi (PDC) sono una rara sottopopolazione dell’immunità innata. Dopo lo sviluppo vengono rilasciate dal midollo osseo e migrano verso gli organi linfoidi secondari. A seguito dell’attivazione dei TLR7/9, le PDC possono svolgere un’attività antitumorale mediante la produzione di IFN-α che influenza negativamente la proliferazione delle cellule tumorali, la linfoangiogenesi tumorale, lo sviluppo delle metastasi e aumenta la citotossicità tumorale. Il segnale autocrino di IFNα/β attivato nelle PDC modula una serie di geni indotti da I-IFN come CXCL-10/IP-10, chemochina pro-infiammatoria coinvolta nel reclutamento dei leucociti e responsabile della polarizzazione dei linfociti T alla risposta Th1 e Th17. Il reclutamento delle PDC nei tessuti periferici avviene durante stati infiammatori e in diversi tipi di tumori. Nonostante la capacità infiltrante, la funzione antitumorale delle PDC è ancora controversa probabilmente influenzata dal coinvolgimento del microambiente tumorale. La precedente analisi di un’estesa coorte di Melanomi Primitivi Cutanei (PCM) ha mostrato un reclutamento selettivo delle PDC all’interno del tumore che però non è risultato in una correlazione con il quantitativo di IFN-α prodotto. In questo studio abbiamo dimostrato un forte decremento della densità delle PDC nelle metastasi rispetto ai PCM che potrebbe indicare un ridotto output midollare oppure un difetto delle capacità migratorie delle PDC. Nella coorte di pazienti metastatici (MM), l’analisi del profilo dei recettori chemochinici coinvolti nella migrazione ha rivelato una mancata attivazione delle PDC circolanti. Inoltre, è presente una riduzione nella frequenza di PDC e di cellule dendritiche mieloidi (MDC) nel sangue correlabile con il carico di malattia dei pazienti MM. La stimolazione con gli agonisti dei TLR7/9, ha mostrato l’incapacità di produzione di IFN-α e IP-10 delle PDC di pazienti di MM. La costitutiva iperattivazione della pathway di RAF/MEK/ERK è comune nei pazienti di melanoma cutaneo. Il regime terapeutico dei pazienti MM con profilo mutazionale positivo per BRAF consiste nella combinazione di inibitori di BRAF (BRAFi: Vemurafenib e Dabrafenib) e MEK (MEKi: Trametinib and Cometinib). La risposta clinica di Vemurafenib è parzialmente mediata dall’attivazione del sistema immunitario, anche attraverso la modulazione della funzione delle cellule dendritiche. L’analisi dei pazienti sottoposti a terapia ha mostrato che le frequenze delle PDC e delle MDC rimangono invariate durante il trattamento, nonostante un’effettiva risposta clinica dei pazienti. L’analisi dei singoli pazienti non ha evidenziato il recupero nel pool delle PDC e delle MDC circolanti e della produzione di IFN-α e IP-10 a seguito della terapia. Questo dato può indicare un eventuale residuo di malattia microscopica che potrebbe interferire con le funzioni delle PDC. Altra ipotesi è che la somministrazione di BRAFi e MEKi può avere degli effetti diretti sulle funzioni delle PDC. Dati preliminari ottenuti su PDC purificate da donatori sani (HD) dimostrano che dosi terapeutiche di Vemurafenib non influenzano la vitalità delle cellule. Probabilmente la riduzione funzionale delle PDC osservata è dovuta a fattori prodotti dalle cellule di melanoma ancora presenti nell’organismo. Grazie all’utilizzo di PDC purificate da HD, è’ stato possibile mimare l’effetto esercitato da fattori solubili secreti dalle cellule di melanoma raccolti nel surnatante tumorale (SN-mel). Il condizionamento di 24 h con SN-mel ha provocato una diminuzione della vitalità delle PDC. Inoltre, a seguito dell’esposizione delle cellule SN-mel abbiamo potuto osservare una diminuzione del segnale di membrane di BDCA-2 e una significativa riduzione della produzione di IFN-α e IP-10 a seguito della stimolazione dei TLR7/9. Questi dati suggeriscono che componenti biochimici e ligandi prodotti dalle cellule di melanoma possono influenzare la sopravvivenza e la funzionalità delle PDC.
Plasmacytoid Dendritic Cells (PDC) are a rare innate immune cells subpopulation .After development, PDC are realised by the bone marrow into the blood stream and migrate from bone marrow to lymph nodes, mucosal associated lymphoid tissue and spleen in steady state conditions. Properly activated PDC may exert antitumor activity through TLR7/9 dependent IFN-α production. IFN-ɑ affects tumor cell proliferation, tumor lymph/angiogenesis, tumor metastasis and enhances the NK cell citoxicity against tumor cells. Autocrine IFNα/β signalling in PDC also modulates a set of interferon-inducible genes such CXCL10/IP-10. IP-10 is a pro-inflammatory chemokine involved in leucocytes recruitment and responsible of Th1 and Th17 polarization of T-cell. PDC recruitment in peripheral tissue has been reported during inflammation and in several types of tumor such as melanoma, head and neck cancer, ovarian carcinoma and breast cancer. Despite of infiltration in many cancers, the PDC anti-tumoral function is still debating. Recent data suggest that PDC could exert a negative regulator role of antitumor response. Emerging hypothesis explains the controversial function of PDC with the tumour microenvironment involvement in subversion of their anti-tumoral activity. Our previous unpublished data on a large cohort of Primary Cutaneous Melanoma (PCM) showed that PDC density within the tumor fails to correlate with a good prognosis in term of IFN-α production. Analysing a cohort of Metastatic Melanoma (MM) patients, we reported a striking decrease of PDC in MM tissues compared to PCM suggesting a severe defect of this population during advanced disease stage. This observation might indicate a reduced PDC bone marrow output or, alternatively, defective migratory properties of PDC. Analysis of Chemokine Receptor (CKR) repertoire of circulating PDC of MM patients suggested lack of activation of these cells. In addition, a significant reduction of circulating PDC and Myeloid Dendritic Cell (MDC) frequencies was detected in blood of MM patients. Interestingly, PDC and MDC reduction was correlated with the tumor burden of MM patients. Moreover, stimulation of TLR7/9 agonists resulted in PDC impairment of MM patients in IFN-α and IP-10 production. Constitutive hyper-activation of the RAF/MEK/ERK pathway is common in melanoma. Combination of BRAF (BRAFi: Vemurafenib and Dabrafenib) and MEK (MEKi: Trametinib and Cometinib) inhibitors represents the standard of care for BRAF mutated MM patients. It is interesting to note that clinical response to Vemurafenib is partially mediated by the immune system. Recently, it has been demonstrated that exposure to MEKi and BRAFi might modulate dendritic cell function. So, we extended the analysis to patients treated with target therapies (i.e. Vemurafenib, Dabrafenib, Trametinib and Cometinib). In our cohort, PDC and MDC frequencies remained unchanged during treatment and single patient analysis revealed no recovery in blood MDC and PDC pool during the treatment. Similarly, PDC capability to produce IFN-α and IP-10 was not restored. This might indicate that microscopic residual disease interferes with PDC function. Alternatively, BRAFi and MEKi might exert some direct effect on PDC function. Our preliminary data obtained on purified PDC suggested that at the therapeutic dose of Vemurafenib cell viability was not affected. Experiments based on an in vitro culture model have enabled us to mimick the direct impact of melanoma cells. PDC viability was affected by melanoma cell supernatant (SN-mel) after 24h of exposure and the death rate was different among different melanoma cell lines. In our experiments, we could observed a downregulation of surface BDCA-2 on PDC after SN-mel exposure. In addition, SN-mel significantly reduced IFN-α and IP-10 production by TLR 7/9 agonists stimulation. These finding suggest that biochemical compounds and ligands produced by melanoma cells affect the survival and function of PDC.