CXCR4 inhibition in human pancreatic and colorectal cancers induces an integrated immune response.

Inhibition of the chemokine receptor CXCR4 in combination with blockade of the PD-1/PD-L1 T cell checkpoint induces T cell infiltration and anticancer responses in murine and human pancreatic cancer. Here we elucidate the mechanism by which CXCR4 inhibition affects the tumor immune microenvironment. In human immune cell-based chemotaxis assays, we find that CXCL12-stimulated CXCR4 inhibits the directed migration mediated by CXCR1, CXCR3, CXCR5, CXCR6, and CCR2, respectively, chemokine receptors expressed by all of the immune cell types that participate in an integrated immune response. Inhibiting CXCR4 in an experimental cancer medicine study by 1-wk continuous infusion of the small-molecule inhibitor AMD3100 (plerixafor) induces an integrated immune response that is detected by transcriptional analysis of paired biopsies of metastases from patients with microsatellite stable colorectal and pancreatic cancer. This integrated immune response occurs in three other examples of immune-mediated damage to noninfected tissues: Rejecting renal allografts, melanomas clinically responding to anti-PD1 antibody therapy, and microsatellite instable colorectal cancers. Thus, signaling by CXCR4 causes immune suppression in human pancreatic ductal adenocarcinoma and colorectal cancer by impairing the function of the chemokine receptors that mediate the intratumoral accumulation of immune cells.Stand Up 2 Cancer, Lustgarten Foundation, NIH

Identification of unique neoantigen qualities in long-term survivors of pancreatic cancer

Pancreatic ductal adenocarcinoma is a lethal cancer with fewer than 7% of patients surviving past 5 years. T-cell immunity has been linked to the exceptional outcome of the few long-term survivors1,2, yet the relevant antigens remain unknown. Here we use genetic, immunohistochemical and transcriptional immunoprofiling, computational biophysics, and functional assays to identify T-cell antigens in long-term survivors of pancreatic cancer. Using whole-exome sequencing and in silico neoantigen prediction, we found that tumours with both the highest neoantigen number and the most abundant CD8+ T-cell infiltrates, but neither alone, stratified patients with the longest survival. Investigating the specific neoantigen qualities promoting T-cell activation in long-term survivors, we discovered that these individuals were enriched in neoantigen qualities defined by a fitness model, and neoantigens in the tumour antigen MUC16 (also known as CA125). A neoantigen quality fitness model conferring greater immunogenicity to neoantigens with differential presentation and homology to infectious disease-derived peptides identified long-term survivors in two independent datasets, whereas a neoantigen quantity model ascribing greater immunogenicity to increasing neoantigen number alone did not. We detected intratumoural and lasting circulating T-cell reactivity to both high-quality and MUC16 neoantigens in long-term survivors of pancreatic cancer, including clones with specificity to both high-quality neoantigens and predicted cross-reactive microbial epitopes, consistent with neoantigen molecular mimicry. Notably, we observed selective loss of high-quality and MUC16 neoantigenic clones on metastatic progression, suggesting neoantigen immunoediting. Our results identify neoantigens with unique qualities as T-cell targets in pancreatic ductal adenocarcinoma. More broadly, we identify neoantigen quality as a biomarker for immunogenic tumours that may guide the application of immunotherapies

Modulation of the tumor microenvironment by the CXCR4 antagonist AMD3100 in pancreatic and colorectal adenocarcinoma

Immunotherapy with checkpoint inhibitors has not been effective thus far in patients with micro-satellite stable pancreatic ductal adenocarcinoma (PDAC), which suggests an immunosuppressive mechanism operates within the tumour microenvironment (TME) of PDAC. In the KRasG12D; p53R172H; Pdx1-Cre (KPC) genetically engineered mouse model of PDAC, T cells are excluded from tumour nests and this effect is related to the chemokine CXCL12 produced by FAP+ stromal cells. Targeting the CXCL12/CXCR4 pathway with AMD3100, a CXCR4 antagonist, resulted T cell infiltration and tumor regression with anti-PD-L1 therapy in the KPC model. The CAMPLEX clinical trial was initiated to assess the safety of a 7-day AMD3100 infusion and provide proof-of-concept that AMD3100 reverses CXCL12 mediated immune-suppression in the TME. The safety and pharmacokinetic results from the CAMPLEX dose escalation phase are presented. A dose-rate of AMD3100 80ug/kg/hr was safe, reasonably well tolerated, and achieved relevant plasma concentrations at steady state. However, pharmacodynamic makers of CXCR4 inhibition, including peripheral white blood cell and CD34+ cell mobilization, were maximal at the lowest dose-rate of 20ug/kg/hr, with little drug-related adverse events. An increase in T cell infiltration was observed in paired pre/post infusion tumour biopsies in a subset of patients, consistent with the pre-clinical KPC data. To further characterize the pharmacodynamic effects of AMD3100 on the TME, additional pre-clinical experiments in the KPC model were performed. Increased CXCR4 protein expression within the TME is a robust effect of AMD3100, which was also observed in the CAMPLEX biopsies. Furthermore, there was a large increase in the infiltration of F4/80+ macrophages at 6 days in KPC mice receiving a high dose of AMD3100. Further studies are warranted to determine their source, polarization, and whether they are related to the anti-tumour effects of AMD3100

Stereotactic Body Radiotherapy for Extracranial Oligometastatic Disease from Head and Neck Primary Cancers: A Systematic Review and Meta-Analysis

Introduction: Stereotactic body radiotherapy (SBRT) is increasingly used to treat disease in the oligometastatic (OM) setting due to mounting evidence demonstrating its efficacy and safety. Given the low population representation in prospective studies, we performed a systematic review and meta-analysis of outcomes of HNC patients with extracranial OM disease treated with SBRT. Methods: A systematic review was conducted with Cochrane, Medline, and Embase databases queried from inception to August 2022 for studies with extracranial OM HNC treated with stereotactic radiotherapy. Polymetastatic patients (>five lesions), mixed-primary cohorts failing to report HNC separately, lack of treatment to all lesions, nonquantitative endpoints, and other definitive treatments (surgery, conventional radiotherapy, and radioablation) were excluded. The meta-analysis examined the pooled effects of 12- and 24-month local control (LC) per lesion, progression-free survival (PFS), and overall survival (OS). Weighted random-effects were assessed using the DerSimonian and Laird method, with heterogeneity evaluated using the I2 statistic and Cochran Qtest. Forest plots were generated for each endpoint. Results: Fifteen studies met the inclusion criteria (639 patients, 831 lesions), with twelve eligible for quantitative synthesis with common endpoints and sufficient reporting. Fourteen studies were retrospective, with a single prospective trial. Studies were small, with a median of 32 patients (range: 6–81) and 63 lesions (range: 6–126). The OM definition varied, with a maximum of two to five metastases, mixed synchronous and metachronous lesions, and a few studies including oligoprogressive lesions. The most common site of metastasis was the lung. Radiation was delivered in 1–10 fractions (20–70 Gy). The one-year LC (LC1), reported in 12 studies, was 86.9% (95% confidence interval [CI]: 79.3–91.9%). LC2 was 77.9% (95% CI: 66.4–86.3%), with heterogeneity across studies. PFS was reported in five studies, with a PFS1 of 43.0% (95% CI: 35.0–51.4%) and PFS2 of 23.9% (95% CI: 17.8–31.2%), with homogeneity across studies. OS was analyzed in nine studies, demonstrating an OS1 of 80.1% (95% CI: 74.2–85.0%) and OS2 of 60.7% (95% CI: 51.3–69.4%). Treatment was well tolerated with no reported grade 4 or 5 toxicities. Grade 3 toxicity rates were uniformly below 5% when reported. Conclusions: SBRT offers excellent LC and promising OS, with acceptable toxicities in OM HNC. Durable PFS remains rare, highlighting the need for effective local or systemic therapies in this population. Further investigations on concurrent and adjuvant therapies are warranted

Prostate Cancer Brain Metastasis: Review of a Rare Complication with Limited Treatment Options and Poor Prognosis

Brain metastases (BM) are perceived as a rare complication of prostate cancer associated with poor outcome. Due to limited published data, we conducted a literature review regarding incidence, clinical characteristics, treatment options, and outcomes of patients with prostate cancer BM. A literature analysis of the PubMed, MEDLINE, and EMBASE databases was performed for full-text published articles on patients diagnosed with BM from prostate cancer. Eligible studies included four or more patients. Twenty-seven publications were selected and analyzed. The sources of published patient cohorts were retrospective chart reviews, administrative healthcare databases, autopsy records, and case series. BM are rare, with an incidence of 1.14% across publications that mainly focus on intraparenchymal metastases. Synchronous visceral metastasis and rare histological prostate cancer subtypes are associated with an increased rate of BM. Many patients do not receive brain metastasis-directed local therapy and the median survival after BM diagnosis is poor, notably in patients with multiple BM, dural-based metastases, or leptomeningeal dissemination. Overall, prostate cancer BM are rare and associated with poor prognosis. Future research is needed to study the impact of novel prostate cancer therapeutics on BM incidence, to identify patients at risk of BM, and to characterize molecular treatment targets

A Novel Strategy to Improve Radiotherapy Effectiveness: First-in-Human MR-guided Focused Ultrasound-Stimulated Microbubbles (MRgFUS+MB) Radiation Enhancement Treatment

Background and aim: Preclinical in vitro and in vivo experiments suggest that radiation-induced tumour cell death can be enhanced 10- to 40-fold when combined with focused-ultrasound (FUS)-stimulated microbubbles (MB). The acoustic exposure of MB in the tumour volume causes vasculature perturbation, activation of the acid sphingomyelinase (ASMase) ceramide pathway, and resultant endothelial cell apoptosis. When the tumour is subsequently treated with radiation, there is increased endothelial cell death and anoxic tumour killing. Here we describe a first-in-human experience treating patients with magnetic resonance (MR)-guided FUS-stimulated MB (MRgFUS+MB) radiation enhancement.Case presentation: A head and neck cancer patient with recurrent disease underwent radiotherapy for 5 separate sites of locoregional disease followed by systemic therapy. The first consisted of a course of 45 Gy in 5 fractions alone, the second of 30 Gy in 5 fractions with hyperthermia, and the three others of 20-30 Gy in 5 fractions along with MRgFUS+MB treatment. The treatment methodology used an MR-coupled FUS-device operating at 500 KHz and 540 kPa peak negative pressure with an insonification time of 750 ms spread over 5 minutes to stimulate intravenously administered MB within tumour target. All sites treated with stimulated MB had a complete radiological response, and subsequently, the patient’s other cutaneous metastatic disease disappeared. The patient has been under surveillance for over two years without active treatment or disease progression.Discussion: MRgFUS+MB was well-tolerated with no reported treatment-related adverse events, which can be attributed to the capability of FUS to selectively stimulate MB within the tumour volume while sparing the surrounding normal tissue. Sustained local control at all target sites aligns with earlier preclinical findings suggesting the radiation enhancement potential of FUS+MB.Conclusion: MRgFUS+MB represents a novel and promising therapy for enhancing radiation efficacy and improving therapeutic index with potential improvements in disease control