Colorectal cancer-specific IFNβ delivery overcomes dysfunctional dsRNA-mediated type I interferon signaling to increase the abscopal effect of radiotherapy

BACKGROUND

Cancer-intrinsic type I interferon (IFN-I) production triggered by radiotherapy (RT) is mainly dependent on cytosolic double-stranded DNA (dsDNA)-mediated cGAS/STING signaling and increases cancer immunogenicity and enhances the antitumor immune response to increase therapeutic efficacy. However, cGAS/STING deficiency in colorectal cancer (CRC) may suppress the RT-induced antitumor immunity. Therefore, we aimed to evaluate the importance of the dsRNA-mediated antitumor immune response induced by RT in patients with CRC.

METHODS

Cytosolic dsRNA level and its sensors were evaluated via cell-based assays (co-culture assay, confocal microscopy, pharmacological inhibition and immunofluorescent staining) and in vivo experiments. Biopsies and surgical tissues from patients with CRC who received preoperative chemoradiotherapy (neoCRT) were collected for multiplex cytokine assays, immunohistochemical analysis and SNP genotyping. We also generated a cancer-specific adenovirus-associated virus (AAV)-IFNβ1 construct to evaluate its therapeutic efficacy in combination with RT, and the immune profiles were analyzed by flow cytometry and RNA-seq.

RESULTS

Our studies revealed that RT stimulates the autonomous release of dsRNA from cancer cells to activate TLR3-mediated IFN-I signatures to facilitate antitumor immune responses. Patients harboring a dysfunctional TLR3 variant had reduced serum levels of IFN-I-related cytokines and intratumoral CD8+ immune cells and shorter disease-free survival following neoCRT treatment. The engineered cancer-targeted construct AAV-IFNβ1 significantly improved the response to RT, leading to systematic eradication of distant tumors and prolonged survival in defective TLR3 preclinical models.

CONCLUSION

Our results support that increasing cancer-intrinsic IFNβ1 expression is an immunotherapeutic strategy that enhances the RT-induced antitumor immune response in locally patients with advanced CRC with dysfunctional TLR3.

Activation of STING by the novel liposomal TLC388 enhances the therapeutic response to anti-PD-1 antibodies in combination with radiotherapy

Current immune checkpoint inhibiters (ICIs) have contrasting clinical results in poorly immunogenic cancers such as microsatellite-stable colorectal cancer (MSS-CRC). Therefore, understanding and developing the combinational therapeutics for ICI-unresponsive cancers is critical. Here, we demonstrated that the novel topoisomerase I inhibitor TLC388 can reshape the tumor immune landscape, corroborating their antitumor effects combined with radiotherapy as well as immunotherapy. We found that TLC388 significantly triggered cytosolic single-stranded DNA (ssDNA) accumulation for STING activation, leading to type I interferons (IFN-Is) production for increased cancer immunogenicity to enhance antitumor immunity. TLC388-treated tumors were infiltrated by a vast number of dendritic cells, immune cells, and costimulatory molecules, contributing to the favorable antitumor immune response within the tumor microenvironment. The infiltration of cytotoxic T and NK cells were more profoundly existed within tumors in combination with radiotherapy and ICIs, leading to superior therapeutic efficacy in poorly immunogenic MSS-CRC. Taken together, these results showed that the novel topoisomerase I inhibitor TLC388 increased cancer immunogenicity by ssDNA/STING-mediated IFN-I production, enhancing antitumor immunity for better therapeutic efficacy in combination with radiotherapy and ICIs for poorly immunogenic cancer.

Dual Inhibition of B7-H3 and EGFR Overcomes Acquired Chemoresistance in Colon Adenocarcinoma

Despite advances in therapeutic strategies for colorectal cancer (CRC), CRC has a high disease incidence with significant morbidity and mortality worldwide. Notably, immunotherapy has shown limited efficacy in treating metastatic CRC, underscoring the need for alternative immunotherapeutic targets for the management of metastatic colorectal cancer (mCRC). In the present study, we evaluated the levels of the immune checkpoint proteins PD-L1, PD-L2 and B7-H3 in a large cohort retrospective study. We found that tumor B7-H3 (52.7%) was highly expressed in primary tumors compared to that in PD-L1 (33.6%) or PD-L2 (34.0%). Elevated B7-H3 expression was associated with advanced stage and the risk of distant metastasis and correlated with poor disease-free survival (DFS), suggesting that tumor B7-H3 was an independent prognostic factor associated with worse DFS in colon adenocarcinoma patients (COAD), especially high-risk COAD patients who received adjuvant chemotherapy. Furthermore, we found that B7-H3 significantly promoted cell proliferation and tumor growth in CRC. B7-H3 may stabilize EGFR to activate its downstream pathway for cancer cell proliferation and resistance to oxaliplatin (OXP). Dual targeting of B7-H3 and EGFR markedly rescued the susceptibility to chemotherapy in colorectal cancer cells in vitro and in vivo. Overall, these results showed that B7-H3 exhibited a high prevalence in COAD patients and was significantly associated with worse prognosis in COAD patients. Dual targeting of B7-H3 and EGFR signaling might be a potential therapeutic strategy for high-risk COAD patients.

Prognostic Value of Immune Cells Subsets Within the Tumor Microenvironment in Patients With Rectal Adenocarcinoma

BACKGROUND/AIM

One-third of newly diagnosed colorectal cancer cases are rectal cancers. Multimodal treatment regimens including surgery, radiotherapy, and chemotherapy improve local control and survival outcome and decrease tumor relapse for patients with rectal adenocarcinoma (READ). However, stratification of patients to predict their responses is urgently needed to improve therapeutic responses.

PATIENTS AND METHODS

Immunostainings of CD3+, CD8+, and CD45RO+ immune cell subsets within the tumor microenvironment were evaluated using immunohistochemistry in two hundred seventy-nine READ patients.

RESULTS

In this study, we found that examination of the adaptive immune response by quantifying CD3+, CD8+, and CD45RO+ immune cell subsets, provides improved and independent prognostic value for patients with READ. Regardless of conventional clinical and pathologic parameters, the densities of T cell subsets were strongly related to a better prognosis in patients with READ. High density of intratumoral immune cells is associated with absence of nodal metastasis, lymphovascular invasion, and perineural invasion. Moreover, high tumor-infiltrating lymphocyte (TIL) subsets were associated with favorable survival outcome in patients with READ, especially high-risk patients with advanced READ.

CONCLUSION

Immune cell subsets including CD3, CD8, and CD45RO within the tumor microenvironment were independent prognostic factors for patients with READ.

TNFα modulates PANX1 activation to promote ATP release and enhance P2RX7-mediated antitumor immune responses after chemotherapy in colorectal cancer

ATP and its receptor P2RX7 exert a pivotal effect on antitumor immunity during chemotherapy-induced immunogenic cell death (ICD). Here, we demonstrated that TNFα-mediated PANX1 cleavage was essential for ATP release in response to chemotherapy in colorectal cancer (CRC). TNFα promoted PANX1 cleavage via a caspase 8/3-dependent pathway to enhance cancer cell immunogenicity, leading to dendritic cell maturation and T-cell activation. Blockade of the ATP receptor P2RX7 by the systemic administration of small molecules significantly attenuated the therapeutic efficacy of chemotherapy and decreased the infiltration of immune cells. In contrast, administration of an ATP mimic markedly increased the therapeutic efficacy of chemotherapy and enhanced the infiltration of immune cells in vivo. High PANX1 expression was positively correlated with the recruitment of DCs and T cells within the tumor microenvironment and was associated with favorable survival outcomes in CRC patients who received adjuvant chemotherapy. Furthermore, a loss-of-function P2RX7 mutation was associated with reduced infiltration of CD8+ immune cells and poor survival outcomes in patients. Taken together, these results reveal that TNFα-mediated PANX1 cleavage promotes ATP-P2RX7 signaling and is a key determinant of chemotherapy-induced antitumor immunity.

Dysfunctional TLR1 reduces the therapeutic efficacy of chemotherapy by attenuating HMGB1-mediated antitumor immunity in locally advanced colorectal cancer

Regional lymph node metastasis is an important predictor for survival outcome and an indicator for postoperative adjuvant chemotherapy in patients with colorectal cancer. Even with advances in adjuvant chemotherapeutic regimens, 5-year distant metastasis and survival rates are still unsatisfactory. Here, we evaluate the clinical significance of polymorphisms in receptors for HMGB1, which is the hallmark of chemotherapy-induced immunogenic cell death, in patients with stage II-III colon carcinoma (COAD). We found that high cytosolic HMGB1 is elicited in stage III COAD patients who received adjuvant chemotherapy. Patients with the TLR1-N248S polymorphism (rs4833095), which causes loss-of-function in HMGB1-mediated TLR1-TLR2 signaling, may influence the therapeutic efficacy of adjuvant chemotherapy, leading to a high risk of distant metastasis within 5 years [HR = 1.694, 95% CI = 1.063-2.698, p = 0.027], suggesting that TLR1-N248S is an independent prognostic factor for locally advanced colon carcinoma patients. We found that defective TLR1 impaired TLR1/2 signaling during dendritic cell (DC) maturation for the antitumor immune response under immunogenic chemotherapy oxaliplatin (OXP) treatment. Defective TLR1 on DCs impaired their maturation ability by HMGB1 and reduced the secretion of IFNγ from T cells to eradicate tumor cells in vitro. Moreover, systemic inhibition of TLR1/2 dramatically reduced the tumor-infiltrating immune cells by OXP treatment, leading to poor therapeutic response to OXP. In contrast, administration of a TLR1/2 agonist synergistically increased the benefit of OXP treatment and triggered a high density of tumor-infiltrating immune cells. We also observed that fewer tumor-infiltrating cytotoxic T lymphocytes were located within the tumor microenvironment in patients bearing the TLR1-N248S polymorphism. Overall, our results suggest that dysfunctional TLR1 may reduce the therapeutic response to adjuvant chemotherapy by impairing HMGB1-mediated DC maturation and attenuating the antitumor immune response in locally advanced colon carcinoma patients.

Neoantigen Cancer Vaccine for Immunologically Cold Microsatellite-stable Colorectal Cancer

PURPOSE/OBJECTIVE(S)

Immunotherapies, such as immune checkpoint inhibitors (ICIs), have revolutionized management of some cancers but have little benefit for microsatellite-stable colorectal cancer patients (MSS-CRC). This is, in part, due to the low mutations and neoantigen expression in this immunogenically "cold" MSS-CRC. Therefore, we aim to develop novel shared neoantigen-based therapeutic cancer vaccine to reinvigorate antitumor immunity and enhance the therapeutic benefit of radiotherapy in MSS-CRC.

MATERIALS/METHODS

To identify novel highly expressed and shared neoantigens, we collected 40 match-paired adjacent normal and tumor tissues from MSS-CRC patients for WES-seq, RNA-seq, and liquid chromatography-MS/MS (LC-MS/MS). By incorporating these databases, we established Neoantigen Discovery and Validation (NeoDiva) system to identify a cluster of highly expressed and shared neoantigens derived from non-coding regions and evaluate its immunogenicity by HLA-A*11 transgenic mice. We then develop a neoantigen-based therapeutic cancer vaccine by an engineered adenovirus-associated virus (AAV) to evaluate its therapeutic efficacy in combination with radiotherapy in MSS-CRC animal model.

RESULTS

We identified a cluster of highly expressed and shared neoantigens (HLA-A*11-restricted) derived from non-coding regions. The immunogenicity of these novel neoantigens was demonstrated by HLA-A*11 transgenic mice and ex vivo stimulation. Moreover, the engineered AAV-based neoantigen cancer vaccine significantly eradicates cancer cells, prevents distant metastasis, prolong survival period in combination with radiotherapy. By flow cytometry, ELISPOT and MHC-I-tetramer assay, we demonstrated the recruitment of tumor-infiltrating lymphocytes was remarkably increased and neoantigen-specific T cell response was enhanced. Moreover, these isolated neoantigen-specific T cells can recognize cancer cells and produce IFNg to kill cancer cells.

CONCLUSION

Neoantigens identified by our NeoDiVa platform, via the combination of radiotherapy and a novel AAV vaccine delivery system, boosted antigen-specific T-cell function and improve tumor control of limnologically "cold" MSS colorectal cancer in vivo. We are in the process of obtaining an IND and initiating Phase I/II clinical trial to validate safety and efficacy of these exciting findings.

Impact of Pattern Recognition Receptors on the Prognosis of Chemotherapy-treated Rectal Cancer Patients

BACKGROUND/AIM

Chemotherapeutic drugs or radiation can cause immunogenic cell death (ICD) and damage-associated molecular pattern (DAMP) release to activate pattern recognition receptor (PRR) in immune cells. Several PRRs bridge innate immunity and adaptive immunity and are implicated in the anticancer immune response. However, single nucleotide polymorphisms (SNPs) in PRRs are associated with chemotherapeutic drugs or radiation response in cancer treatment.

PATIENTS AND METHODS

We enrolled 117 patients with rectal cancer who received surgery with or without postoperative chemotherapy and examined the SNPs in PRRs from formalin-fixed, paraffin embedded tissues. The genotypes of RAGE (G82S/rs2070600), P2RX7 (E496A/rs3751143), and FPR1 (E346A/rs867228) were determined and analyzed using the MassARRAY platform.

RESULTS

We integrated the status of PRR polymorphism into the PRR score and found that the PRR score was significantly associated with 10-year disease-free survival (DFS) (p=0.025) in patients with rectal cancer. Moreover, the PRR score was an independent risk factor for 10-year DFS (HR=4.400, 95%CI=1.607-12.212, p=0.004) and 10-year overall survival (OS) (HR=4.674, 95%CI=1.423-16.038, p=0.011) in patients with rectal cancer treated postoperatively with adjuvant chemotherapy.

CONCLUSION

The PRR score is an independent prognostic factor for the survival outcome of patients with rectal cancer, especially those treated postoperatively with adjuvant chemotherapy. PRR score evaluation may be used as a biomarker in the clinic.

Health Economic Evaluation of Proton Therapy for Lung Cancer: A Systematic Review

BACKGROUND

To our knowledge, there have been no systematic reviews of health economic evaluations of proton therapy specific to lung cancer.

METHODS

We conducted this systematic review according to the predefined protocol [PROSPERO CRD42022365869]. We summarized the results of the included studies via structured narrative synthesis.

RESULTS

We identified four studies (all used passively scattered proton therapy) from 787 searches. Two cost analyses reported that proton therapy was more costly than photon therapy for early- or locally advanced-stage non-small cell lung cancer, one cost-utility analysis reported that proton therapy was dominated by nonproton therapy in early-stage non-small cell lung cancer, and one cost-utility analysis reported that proton therapy was not cost-effective (vs. photon) in locally advanced non-small cell lung cancer.

CONCLUSIONS

Passively scattered proton therapy was more costly and not cost-effective than photon therapy for early- and locally advanced-stage non-small cell lung cancer. Further health economic evaluations regarding modern proton therapy (such as scanning beam) for common radiotherapy indications of lung cancer are eagerly awaited.

Targeting CD73 increases therapeutic response to immunogenic chemotherapy by promoting dendritic cell maturation

The CD39-CD73-adenosinergic pathway converts adenosine triphosphate (ATP) to adenosine for inhibiting anti-tumor immune responses. Therefore, targeting CD73 to reinvigorate anti-tumor immunity is considered the novel cancer immunotherapy to eradicate tumor cells. To fully understand the critical role of CD39/CD73 in colon adenocarcinoma (COAD), this study aims to comprehensive investigate the prognostic significance of CD39 and CD73 in stage I-IV COAD. Our data demonstrated that CD73 staining strongly marked malignant epithelial cells and CD39 was highly expressed in stromal cells. Attractively, tumor CD73 expression was significantly associated with tumor stage and the risk of distant metastasis, which suggested CD73 was as an independent factor for colon adenocarcinoma patients in univariate COX analysis [HR = 1.465, 95%CI = 1.084-1.978, p = 0.013]; however, high stromal CD39 in COAD patients was more likely to have favorable survival outcome [HR = 1.458, p = 1.103-1.927, p = 0.008]. Notably, high CD73 expression in COAD patients showed poor response to adjuvant chemotherapy and high risk of distant metastasis. High CD73 expression was inversely associated with less infiltration of CD45⁺ and CD8⁺ immune cells. However, administration with anti-CD73 antibodies significantly increased the response to oxaliplatin (OXP). Blockade of CD73 signaling synergistically enhanced OXP-induced ATP release, which is a marker of immunogenic cell death (ICD), promotes dendritic cell maturation and immune cell infiltration. Moreover, the risk of colorectal cancer lung metastasis was also decreased. Taken together, the present study revealed tumor CD73 expression inhibited the recruitment of immune cells and correlated with a poor prognosis in COAD patients, especially patients received adjuvant chemotherapy. Targeting CD73 to markedly increased the therapeutic response to chemotherapy and inhibited lung metastasis. Therefore, tumor CD73 may be an independent prognostic factor as well as the potential of therapeutic target for immunotherapy to benefit colon adenocarcinoma patients.

A Novel Engineered AAV-Based Neoantigen Vaccine in Combination with Radiotherapy Eradicates Tumors

The potency of tumor-specific antigen (TSA) vaccines, such as neoantigen (neoAg)-based cancer vaccines, can be compromised by host immune checkpoint inhibitory mechanisms, such as programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1), that attenuate neoAg presentation on dendritic cells (DC) and hinder T cell-mediated cytotoxicity. To overcome PD-1/PD-L1 inhibition in DCs, we developed a novel adeno-associated virus (meAAV) neoAg vaccine, modified with TLR9 inhibitory fragments, PD-1 trap, and PD-L1 miRNA, which extend the persistence of meAAV and activate neoAg-specific T-cell responses in immune-competent colorectal and breast cancer murine models. Moreover, we found that in combination with radiotherapy, the meAAV-based neoAg cancer vaccine not only elicited higher antigen presentation ability, but also maintained neoAg-specific cytotoxic T lymphocyte (CTL) responses. These functional PD-1 traps and PD-L1 miRNAs overcome host PD-1/PD-L1 inhibitory mechanisms and boost the therapeutic efficacy of radiotherapy. More importantly, combined radiotherapy and meAAV neoAg cancer vaccines significantly enhanced neoAg-specific CTL responses, increased CTL infiltration in tumor microenvironment, and decreased tumor-associated immunosuppression. This process led to the complete elimination of colorectal cancer and delayed tumor growth of breast cancer in tumor-bearing mice. Taken together, our results demonstrated a novel strategy that combines neoAg cancer vaccine and radiotherapy to increase the therapeutic efficacy against colorectal and breast cancers.

Engineered sTRAIL-armed MSCs overcome STING deficiency to enhance the therapeutic efficacy of radiotherapy for immune checkpoint blockade

Radiotherapy (RT) mainly elicits antitumor immunity via the cGAS/STING axis for type I interferon (IFN) production. However, dysregulation of cGAS/STING constrains radiotherapy-induced antitumor immunity and type I IFN-dependent cell death and is associated with shorter survival of patients with colorectal cancer (CRC). Due to their tumor tropism, mesenchymal stem cells (MSCs) have shown the potential to deliver therapeutic genes for cancer therapy. Here, we showed that MSCs enhance the sensitivity to RT by inducing TRAIL-dependent cell death and remodel the tumor microenvironment by recruiting CD8⁺ immune cells to upregulate PD-L1 in the tumor. By engineering MSCs to express CRC-specific soluble TRAIL via adenovirus-associated virus 2 (AAV2), we found that the therapeutic activity of MSC-sTRAIL was superior to that of MSCs alone when combined with RT. Combined treatment with MSC-sTRAIL and RT significantly reduced cell viability and increased apoptosis by inducing TRAIL-dependent cell death in STING-deficient colorectal cancer cells. MSC-sTRAIL directly triggered TRAIL-dependent cell death to overcome the deficiency of the cGAS/STING axis. Moreover, these combination treatments of MSC-sTRAIL and RT significantly remodeled the tumor microenvironment, which was more suitable for anti-PD-L1 immunotherapy. Taken together, this therapeutic strategy represents a novel targeted treatment option for patients with colorectal cancer, especially cGAS/STING-deficient patients.

Dual inhibition of TGFβ signaling and CSF1/CSF1R reprograms tumor-infiltrating macrophages and improves response to chemotherapy via suppressing PD-L1

TGFβ contributes to chemoresistance in advanced colorectal cancer (CRC) via diverse immune-microenvironment mechanisms. Here, we found that cancer cell autonomous TGFβ directly triggered tumor programmed cell death 1 ligand 1 (PD-L1) upregulation, resulting in resistance to chemotherapy. Inhibition of tumor PD-L1 expression sensitized cancer cells to chemotherapy, reduced lung metastasis and increased the influx of CD8⁺ T cells. However, chemorefractory cancer cell-derived CSF1 recruited TAMs for TGFβ-mediated PD-L1 upregulation via a vicious cycle. High infiltration of macrophages was clinically correlated with the status of tumor PD-L1 after chemotherapy treatment in CRC patients. We found that depletion of immunosuppressive CSF1R⁺ TAM infiltration and blockade of the TGFβ receptor resulted in an increased influx of cytotoxic CD8⁺ T and effector memory CD8⁺ cells, a reduction in regulatory T cells, and a synergistic inhibition of tumor growth when combined with chemotherapy. These findings show that CSF1R⁺ TAMs and TGFβ are the dominant components that regulate PD-L1 expression within the immunosuppressive tumor microenvironment, providing a therapeutic strategy for advanced CRC patients.

Protein phosphatase 2A inactivation induces microsatellite instability, neoantigen production and immune response

Microsatellite-instable (MSI), a predictive biomarker for immune checkpoint blockade (ICB) response, is caused by mismatch repair deficiency (MMRd) that occurs through genetic or epigenetic silencing of MMR genes. Here, we report a mechanism of MMRd and demonstrate that protein phosphatase 2A (PP2A) deletion or inactivation converts cold microsatellite-stable (MSS) into MSI tumours through two orthogonal pathways: (i) by increasing retinoblastoma protein phosphorylation that leads to E2F and DNMT3A/3B expression with subsequent DNA methylation, and (ii) by increasing histone deacetylase (HDAC)2 phosphorylation that subsequently decreases H3K9ac levels and histone acetylation, which induces epigenetic silencing of MLH1. In mouse models of MSS and MSI colorectal cancers, triple-negative breast cancer and pancreatic cancer, PP2A inhibition triggers neoantigen production, cytotoxic T cell infiltration and ICB sensitization. Human cancer cell lines and tissue array effectively confirm these signaling pathways. These data indicate the dual involvement of PP2A inactivation in silencing MLH1 and inducing MSI.

DNMT1 constrains IFNβ-mediated anti-tumor immunity and PD-L1 expression to reduce the efficacy of radiotherapy and immunotherapy

Radiotherapy can boost the therapeutic response to immune checkpoint inhibitors (ICIs) by recruiting T lymphocytes and upregulating PD-L1 expression within the tumor microenvironment (TME). However, in some cases, tumor PD-L1 expression cannot be induced, even in the presence of abundant T lymphocytes, in locally advanced colorectal cancer patients who receive preoperative neoadjuvant concurrent chemoradiotherapy (CCRT). In this study, we found that PD-L1 promoter methylation is negatively correlated with tumor PD-L1 expression and is an independent biomarker for locally advanced colorectal cancer patients. PD-L1 methylation (mCD274) was significantly associated with shorter disease-free survival (cg15837913 loci, p = .0124). By multivariate Cox proportional hazards analyses including influent factors, mCD274 was classified as an independent prognostic factor for poor 5-year DFS [cg15837913, hazard ratio: HR = 4.06, 95% CI = 1.407-11.716, p = .01]. We found that the immunomodulatory agent DNA methyltransferase inhibitor (DNMTi) led to demethylation of the PD-L1 promoter and increased radiotherapy-induced PD-L1 upregulation via interferon β (IFNβ). DNMTi not only induced tumor PD-L1 expression but increased the expression of immune-related genes as well as intratumoral T cell infiltration in vivo. Furthermore, DNMTi strongly enhanced the response to combined treatment with radiotherapy and anti-PD-L1 inhibitors, and prolonged survival in microsatellite stability (MSS) colorectal model. Therefore, DNMTi remodeled the tumor microenvironment to improve the effect of radiotherapy and anti-PD-L1 immunotherapy by directly triggering tumor PD-L1 expression and eliciting stronger immune responses, which may provide potential clinical benefits to colorectal cancer patients in the future.

An independent predictor of poor prognosis in locally advanced rectal cancer: rs867228 in formyl peptide receptor 1 (FPR1)

Formyl peptide receptor 1 (FPR1) plays a key regulatory role in innate and adaptive immunity. Recently, we reported that the CC genotype of FPR1-E346A (rs867228, c. 1037 A > C) is an independent biomarker for patients with locally advanced rectal cancer (LARC) who received preoperative concurrent chemoradiotherapy (CCRT). Pharmacologic inhibition of FPR1 decreased the migration and infiltration of T lymphocytes into tumor microenvironment after CCRT.

Polymorphism of formyl peptide receptor 1 (FPR1) reduces the therapeutic efficiency and antitumor immunity after neoadjuvant chemoradiotherapy (CCRT) treatment in locally advanced rectal cancer

Immunosurveillance and immunoscavenging prompted by preoperative chemoradiotherapy (CCRT) may contribute to improve local control and increase survival outcomes for patients with locally advanced rectal cancer (LARC). In this study, we investigated several genotypes of pattern recognition receptors (PRRs) and their impact on therapeutic efficacy in LARC patients treated with CCRT. We found that homozygosis of formyl peptide receptor 1 (FPR1) (E346A/rs867228) was associated with reduced 5-year overall survival (OS) by Kaplan-Meier analysis (62% vs. 81%, p = 0.014) and multivariate analysis [hazard ratio (HR) = 3.383, 95% CI = 1.374-10.239, p = 0.007]. Moreover, in an animal model, we discovered that the FPR1 antagonist, Boc-MLF (Boc-1), reduced CCRT therapeutic efficacy and decreased cytotoxic T cells and T effector memory cells after chemoradiotherapy treatment. Pharmacologic inhibition of FPR1 by Boc-1 decreased T lymphocyte migration to irradiated tumor cells. Therefore, these results revealed that the FPR1 genotype participates in CCRT-elicited anticancer immunity by reducing T lymphocytes migration and infiltration, and that the FPR1-E346A CC genotype can be considered an independent biomarker for chemo- and radiotherapy outcomes.

Decitabine Augments Chemotherapy-Induced PD-L1 Upregulation for PD-L1 Blockade in Colorectal Cancer

Programmed cell death-1 (PD-1) has demonstrated impressive clinical outcomes in several malignancies, but its therapeutic efficacy in the majority of colorectal cancers is still low. Therefore, methods to improve its therapeutic efficacy in colorectal cancer (CRC) patients need further investigation. Here, we demonstrate that immunogenic chemotherapeutic agents trigger the induction of tumor PD-L1 expression in vitro and in vivo, a fact which was validated in metastatic CRC patients who received preoperatively neoadjuvant chemotherapy (neoCT) treatment, suggesting that tumor PD-L1 upregulation by chemotherapeutic regimen is more feasible via PD-1/PD-L1 immunotherapy. However, we found that the epigenetic control of tumor PD-L1 via DNA methyltransferase 1 (DNMT1) significantly influenced the response to chemotherapy. We demonstrate that decitabine (DAC) induces DNA hypomethylation, which not only directly enhances tumor PD-L1 expression but also increases the expression of immune-related genes and intratumoral T cell infiltration in vitro and in vivo. DAC was found to profoundly enhance the therapeutic efficacy of PD-L1 immunotherapy to inhibit tumor growth and prolong survival in vivo. Therefore, it can be seen that DAC remodels the tumor microenvironment to improve the effect of PD-L1 immunotherapy by directly triggering tumor PD-L1 expression and eliciting stronger anti-cancer immune responses, providing potential clinical benefits to CRC patients in the future.

Removal of N-Linked Glycosylation Enhances PD-L1 Detection and Predicts Anti-PD-1/PD-L1 Therapeutic Efficacy

Reactivation of T cell immunity by PD-1/PD-L1 immune checkpoint blockade has been shown to be a promising cancer therapeutic strategy. However, PD-L1 immunohistochemical readout is inconsistent with patient response, which presents a clinical challenge to stratify patients. Because PD-L1 is heavily glycosylated, we developed a method to resolve this by removing the glycan moieties from cell surface antigens via enzymatic digestion, a process termed sample deglycosylation. Notably, deglycosylation significantly improves anti-PD-L1 antibody binding affinity and signal intensity, resulting in more accurate PD-L1 quantification and prediction of clinical outcome. This proposed method of PD-L1 antigen retrieval may provide a practical and timely approach to reduce false-negative patient stratification for guiding anti-PD-1/PD-L1 therapy.

Upregulation of tumor PD-L1 by neoadjuvant chemoradiotherapy (neoCRT) confers improved survival in patients with lymph node metastasis of locally advanced rectal cancers

The expression of programmed cell death 1 ligand 1 (PD-L1) and interferon-γ (IFN-γ) is of great interest for the development of chemoradiotherapy and immune checkpoint inhibitor treatments. Patients with nodal metastasis (pN+) tend to have a poor prognosis, even after neoadjuvant chemoradiotherapy (neoCRT) and surgical treatment. In this study, we examined the roles of tumor PD-L1 and IFN-γ before and after neoCRT in locally advanced rectal cancer (LARC) patients. Our results demonstrate that patients with high PD-L1 expression in post-neoCRT tissues exhibit improved 5-year disease-free survival (DFS) and overall survival (OS) compared with those with low PD-L1 expression (p < 0.001). Furthermore, in the pN+ population, patients with high PD-L1 expression in post-neoCRT tissues exhibit improved 5-year DFS and OS. PD-L1 and IFN-γ upregulation increased in tumor tissues after neoCRT, and patients with high PD-L1 and high IFN-γ exhibit improved 5-year DFS and OS (p = 0.04 and p = 0.001, respectively). To the best of our knowledge, this study is the first to demonstrate that PD-L1 upregulation in a pN+ cohort correlates with improved prognosis, which is similar to that in patients without nodal metastasis. Moreover, this study verified that PD-L1 and IFN-γ were upregulated by neoCRT treatment in LARC patients and demonstrated that neoCRT may be useful not only for immune checkpoint inhibitor treatment but also for reinvigorating preexisting anti-cancer immunity.

Clinical significance of programmed death 1 ligand-1 (CD274/PD-L1) and intra-tumoral CD8+ T-cell infiltration in stage II-III colorectal cancer

Programmed cell death-1 (PDCD1/PD-1) and its ligand programmed cell death 1 ligand 1 (CD274/PD-L1) have been reported to suppress anti-tumor T cell-mediated immune responses. However, the clinical significance of CD274 in colorectal cancer were still elusive. We aim to clarify the relationships between CD8+ intratumor-infiltrating lymphocytes (TILs) and CD274 as well as their prognostic values in stage II-III colon carcinoma. Tumor differentiation, perineural invasion (PNI), pN stage and DNA mismatch repair (MMR)-deficient were clearly correlated with CD8+ TILs counts within the tumor microenvironment (p < 0.0001). Furthermore, tumor differentiation and PNI were suggestively correlated with tumor CD274 expression (p = 0.02 and p = 0.0195). Tumor CD274 level was significantly correlated with higher CD8+ TILs (p < 0.0001) but was not associated with MMR-deficient status (p = 0.14). High tumor CD274 expression [hazard ratio (HR) = 2.16, 95% CI = 1.63-2.86, p < 0.0001] and CD8+ TILs [HR = 1.51, 95% CI = 1.19-1.91, p = 0.0007] were associated with improved disease-free survival and overall survival. Additionally, the subgroup of patients who had a high CD8+ TILs/tumor CD274 have better survival outcomes compared with other subgroups (71% vs 53%; p < 0.0001). Therefore, the CD8+ TILs counts and tumor CD274 may be prognostic factors to predict survival and therapeutic responses in stage II-III colon carcinoma patients.

Cytosolic high-mobility group box protein 1 (HMGB1) and/or PD-1+ TILs in the tumor microenvironment may be contributing prognostic biomarkers for patients with locally advanced rectal cancer who have undergone neoadjuvant chemoradiotherapy

Rectal cancer, which comprises 30% of all colorectal cancer cases, is one of the most common forms of cancer in the world. Patients with locally advanced rectal cancer (LARC) are often treated with neoadjuvant chemoradiotherapy (neoCRT) followed by surgery. However, after neoCRT treatment, approximately one-third of the patients progress to local recurrence or distant metastasis. In these studies, we found that patients with tumors that exhibited cytosolic HMGB1(Cyto-HMGB1) translocation and/or the presence of PD-1+ tumor-infiltrating lymphocytes (TILs) before treatment had a better clinical outcome. The better outcome is likely due to the release of HMGB1, which triggers the maturation of dendritic cells (DCs) via TLR4 activation, and the subsequent recruitment of PD-1+ tumor-infiltrating lymphocytes to the tumor site, where they participate in immune-scavenging. In conclusion, our results provide evidence that cyto-HMGB1 and/or PD-1+TIL are not only predictive biomarkers before treatment, but they can also potentially designate patients for personalized oncological management including immunotherapy.

Radiation Exposure and Safety Precautions Following 131Cs Brachytherapy in Patients with Brain Tumors

Cesium-131 (Cs) brachytherapy is a safe and convenient treatment option for patients with resected brain tumors. This study prospectively analyzes radiation exposure in the patient population who were treated with a maximally safe neurosurgical resection and Cs brachytherapy. Following implantation, radiation dose rate measurements were taken at the surface, 35 cm, and 100 cm distances. Using the half-life of Cs (9.69 d), the dose rates were extrapolated at these distances over a period of time (t = 30 d). Data from dosimetry badges and rings worn by surgeons and radiation oncologists were collected and analyzed. Postoperatively, median dose rate was 0.2475 mSv h, 0.01 mSv h, and 0.001 mSv h and at 30 d post-implant, 0.0298 mSv h, 0.0012 mSv h, and 0.0001 mSv h at the surface, 35 cm, and 100 cm, respectively. All but one badge and ring measured a dose equivalent corresponding to ~0 mSv h, while 1 badge measured 0.02/0.02/0.02 mSv h. There was a significant correlation between the number of seeds implanted and dose rate at the surface (p = 0.0169). When stratified by the number of seeds: 4-15 seeds (n = 14) and 20-50 seeds (n = 4) had median dose rates of 0.1475 mSv h and 0.5565 mSv h, respectively (p = 0.0015). Using National Council on Radiation Protection guidelines, this study shows that dose equivalent from permanent Cs brachytherapy for the treatment of brain tumors is limited, and it maintains safe levels of exposure to family and medical personnel. Such information is critical knowledge for the neurosurgeons, radiation oncologists, nurses, hospital staff, and family as this method is gaining nationwide popularity.

Biological imaging in clinical oncology: radiation therapy based on functional imaging

Radiation therapy is one of the most effective tools for cancer treatment. In recent years, intensity-modulated radiation therapy has become increasingly popular in that target dose-escalation can be done while sparing adjacent normal tissues. For this reason, the development of measures to pave the way for accurate target delineation is of great interest. With the integration of functional information obtained by biological imaging with radiotherapy, strategies using advanced biological imaging to visualize metabolic pathways and to improve therapeutic index and predict treatment response are discussed in this article.

Higher locoregional recurrence rate for triple-negative breast cancer following neoadjuvant chemotherapy, surgery and radiotherapy

Background

Breast cancer subtype, determined by expression of estrogen/progesterone receptor (ER/PR) and human epidermal growth factor receptor (HER)-2, is predictive for prognosis. The importance of subtype to locoregional recurrence (LRR) following neoadjuvant chemotherapy (NAC) is unknown, particularly after adjuvant radiotherapy (RT).

Methods

We retrospectively identified 160-breast cancer patients registered at Columbia University Medical Center from 1999 to 2012 treated with NAC, surgery and adjuvant RT.

Results

Patients were grouped by receptor status: hormone receptor positive (HR+) [(ER or PR+)/HER2−; n = 75], HER2+ (n = 46), or triple-negative (TNBC) [ER (−) PR (−) HER2 (−); n = 36]. The median follow-up was 28 months. 92.0% received an anthracycline-taxane based NAC and 80.4% of HER2+ patients received trastuzumab. All underwent surgical resection followed by RT. 15.6% had a pathologic complete response (pCR): 26% of HER2+, 5% of HR+, and 25% of TN. The actuarial rate of DM was 13.8% for the entire cohort, with equivalent rates by subtypes in non-pCR patients. The overall rate of LRR was 8%. However, the LRR rate was significantly higher for TNBC patients (22.2%) than HER2+ (5.6%) (p = 0.025) or HR+ (3.0%) (p = 0.037) in non-pCR group. In the pCR group, two patients had recurrence; one LRR and one a DM, both had TNBC. All LRR occurred in or near the radiation field.

Conclusions

TNBC patients with < pCR to NAC have a significantly higher LRR rate as compared to other subtypes even with surgery and adjuvant RT. Our data support a need to further intensify local therapy in TNBC patients.

Comparison of primary radiation versus robotic surgery plus adjuvant radiation in high-risk prostate cancer: a single center experience

OBJECTIVE

The objective of this study was to compare robotic-prostatectomy plus adjuvant radiation therapy (RPRAT) versus primary RT for high-risk prostate cancer (HRPCa).

MATERIALS AND METHODS

A retrospective chart review was performed for the HRPCa patients treated in our institution between 2000 and 2010. One hundred and twenty-three patients with high-risk disease were identified. The Chi-square test and Fisher's exact test were used to compare local control and distant failure rates between the two treatment modalities. For prostate-specific antigen comparisons between groups, Wilcoxon rank-sum test was used.

RESULTS

The median follow-up was 49 months (range: 3-138 months). Local control, biochemical recurrence rate, distant metastasis, toxicity, and disease-free survival were similar in the two groups.

CONCLUSIONS

Primary RT is an excellent treatment option in patients with HRPCa, is equally effective and less expensive treatment compared with RPRAT. A prospective randomized study is required to guide treatment for patients with HRPCa.

Outcomes of gamma knife radiosurgery, bi-modality & tri-modality treatment regimens for patients with one or multiple brain metastases: the Columbia University Medical Center experience

Optimal treatment of brain metastases (BMs) is debatable. However, surgery or gamma knife radiosurgery (GKRS) improves survival when combined with whole brain radiotherapy (WBRT) versus WBRT alone. We retrospectively reviewed an institutional database of patients treated with GKRS for BMs from 1998 to 2013 to explore effects of single or multi-modality therapies on survival. There were 528 patients with median age 62 years. Histologies included 257 lung, 102 breast, 62 melanoma, 40 renal cell, 29 gastrointestinal, and 38 other primary cancers. Treatments included: 206 GKRS alone, 111 GKRS plus WBRT, 109 GKRS plus neurosurgical resection (NSG), and 102 all three modalities. Median overall survival (mOS) was 16.6 months. mOS among patients with one versus multiple metastasis was 17.2 versus 16.0 months respectively (p = 0.825). For patients with one BM, mOS following GKRS alone, GKRS plus WBRT, GKRS plus NSG, and all three modalities was 9.0, 19.1, 25.5, and 25.0 months, respectively, and for patients with multiple BMs, mOS was 8.6, 20.4, 20.7, 24.5 months for the respective groups. Among all patients, multivariate analysis confirmed that tri-modality group had the longest survival (HR 0.467; 95 % CI 0.350-0.623; p < 0.001) compared to GKRS alone; however, this was not significantly different than bi-modality approaches. Uncontrolled primary extra-CNS disease, age and KPS were also independent predictors of survival. Patients treated with GKRS plus NSG, GKRS plus WBRT, or all three modalities had improved OS versus GKRS alone. In our analysis, resection and GKRS allowed avoidance of WBRT without shortening survival.

Calibration of a detector array through beam profile reconstruction with error-locking

An iterative method is proposed to calibrate radiation sensitivities of an arbitrary two-dimensional (2D) array of detectors. The array is irradiated with a wide open- field beam at the central position, as well as at laterally and longitudinal shifted positions; the 2D beam profile of the wide field is reconstructed iteratively from the ratios of shifted images to the central image. The propagation errors due to output variation and inaccurate array positioning are estimated and removed from the reconstructed beam profile by an error-locking scheme with narrow open-field irradiations. The beam profile is interpolated when necessary and then compared to raw detector responses to determine sensitivities. Two additional methods were implemented for comparison: 1) the commercial iterative calibration method for MapCHECK2 with translation and rotation operations; 2) a labor-intensive noniterative method without the issue of error propagation. A MapCHECK2 2D detector array was used to validate the proposed method with the 6 MV photon beam from a Varian iX linear accelerator. All calibration methods were repeated three times. A total of 5, 9, and 29 irradiations were required to implement the commercial method, the proposed method and the noniterative method respec- tively. Moreover, a 5 mm positioning error was intentionally introduced into the calibration procedures of the commercial and the proposed method to test their robustness. Under the normal operation condition of the linear accelerator and with careful alignment of the MapCHECK2, the deviations of the calibrated sensitivities of the proposed method and commercial method with respect to the noniterative method were 0.30% ± 0.29% and 0.92% ± 0.63% respectively; when the 5 mm positioning error was presented, these two methods resulted in deviations of 0.40% ± 0.36% and 3.58% ± 1.94%, respectively. A patient study suggested that, due to this 5 mm positioning error, the mean DTA (dose to agreement) passing rate by the commercial method was 2.7% lower than that by the noniterative method, whereas the proposed method led to a comparable passing rate. It is evident from this study that the proposed iterative method leads to within 1% mean calibration results to established methods. It requires much fewer number of measurements than noniterative method and is more robust against the positioning error than the commercial iterative method. The method also eliminates the need of rotation operations and, therefore, is applicable to inline detector arrays without rotation function, such as electronic portal imager device (EPID). 

Comparing outcomes in poorly-differentiated versus anaplastic thyroid cancers treated with radiation: a surveillance, epidemiology, and end results analysis

PURPOSE

Poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC) are considered the most aggressive cancers of the head and neck. The aim of the study was to evaluate and compare survival outcomes in PDTC and ATC in a large population-based cohort.

MATERIALS AND METHODS

Patients with PDTC and ATC diagnosed from 1973 to 2008 were obtained from Surveillance, Epidemiology, and End RESULTS database. Kaplan-Meier survival analysis and log-rank analyses were performed to evaluate (1) The effect of histology on cause-specific survival (CSS) and (2) the influence of factors such as treatment, treatment sequence, race, sex, and age on CSS. Multivariate analysis was performed to assess the independent effect of these factors on CSS.

RESULTS

A total of 1352 patients with PDTC and ATC were identified. PDTC constituted 52.4% of patients versus 47.6% for ATC. Median CSS was similar in the two histology groups (P = 0.14). Both PDTC and ATC patients receiving radioisotopes showed a significantly better CSS compared to external beam radiation (P < 0.0001). PDTC and ATC Patients receiving radiation prior to surgery demonstrated a significantly lower CSS compared to patients receiving radiation postoperatively (P < 0.0001). Female gender and black/nonwhite race tended to improve CSS in PDTC and ATC patients (P = 0.29 and P = 0.03, for gender and race, respectively). However, multivariate analysis revealed only type of radiation treatment and age to be independently associated with CSS.

CONCLUSION

This is the first large population-based study evaluating PDTC and ATC outcomes in patients who received radiation treatment. Radioisotope use and timing of radiotherapy (postoperative vs. preoperative) were associated with improved CSS in both histologies.

Phase I/II study of resection and intraoperative cesium-131 radioisotope brachytherapy in patients with newly diagnosed brain metastases

OBJECT

Resected brain metastases have a high rate of local recurrence without adjuvant therapy. Adjuvant whole-brain radiotherapy (WBRT) remains the standard of care with a local control rate > 90%. However, WBRT is delivered over 10-15 days, which can delay other therapy and is associated with acute and long-term toxicities. Permanent cesium-131 ((131)Cs) implants can be used at the time of metastatic resection, thereby avoiding the need for any additional therapy. The authors evaluated the safety, feasibility, and efficacy of a novel therapeutic approach with permanent (131)Cs brachytherapy at the resection for brain metastases.

METHODS

After institutional review board approval was obtained, 24 patients with a newly diagnosed metastasis to the brain were accrued to a prospective protocol between 2010 and 2012. There were 10 frontal, 7 parietal, 4 cerebellar, 2 occipital, and 1 temporal metastases. Histology included lung cancer (16), breast cancer (2), kidney cancer (2), melanoma (2), colon cancer (1), and cervical cancer (1). Stranded (131)Cs seeds were placed as permanent volume implants. The prescription dose was 80 Gy at a 5-mm depth from the resection cavity surface. Distant metastases were treated with stereotactic radiosurgery (SRS) or WBRT, depending on the number of lesions. The primary end point was local (resection cavity) freedom from progression (FFP). Secondary end points included regional FFP, distant FFP, median survival, overall survival (OS), and toxicity.

RESULTS

The median follow-up was 19.3 months (range 12.89-29.57 months). The median age was 65 years (range 45-84 years). The median size of resected tumor was 2.7 cm (range 1.5-5.5 cm), and the median volume of resected tumor was 10.31 cm(3) (range 1.77-87.11 cm(3)). The median number of seeds used was 12 (range 4-35), with a median activity of 3.82 mCi per seed (range 3.31-4.83 mCi) and total activity of 46.91 mCi (range 15.31-130.70 mCi). Local FFP was 100%. There was 1 adjacent leptomeningeal recurrence, resulting in a 1-year regional FFP of 93.8% (95% CI 63.2%-99.1%). One-year distant FFP was 48.4% (95% CI 26.3%-67.4%). Median OS was 9.9 months (95% CI 4.8 months, upper limit not estimated) and 1-year OS was 50.0% (95% CI 29.1%-67.8%). Complications included CSF leak (1), seizure (1), and infection (1). There was no radiation necrosis.

CONCLUSIONS

The use of postresection permanent (131)Cs brachytherapy implants resulted in no local recurrences and no radiation necrosis. This treatment was safe, well tolerated, and convenient for patients, resulting in a short radiation treatment course, high response rate, and minimal toxicity. These findings merit further study with a multicenter trial.

Surveillance, epidemiology, and end results-based analysis of the impact of preoperative or postoperative radiotherapy on survival outcomes for T3N0 rectal cancer

PURPOSE

Preoperative chemoradiation has been established as standard of care for T3/T4 node-positive rectal cancer. Recent work, however, has called into question the overall benefit of radiation for tumors with lower risk characteristics, particularly T3N0 rectal cancers. We retrospectively analyzed T3N0 rectal cancer patients and examined how outcomes differed according to the sequence of treatment received.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) database was used to analyze T3N0 rectal cancer cases diagnosed between 1998 and 2008. Treatment consisted of surgery alone (No RT), preoperative radiation followed by surgery (Neo-Adjuvant RT), or surgery followed by postoperative radiation (Adjuvant RT). Demographic and tumor characteristics of the three groups were compared using t-tests for the comparison of means. Survival information from the SEER database was utilized to estimate cause-specific survival (CSS) and to generate Kaplan-Meier survival curves. Multivariate analysis (MVA) of features associated with outcomes was conducted using Cox proportional hazards regression models with Adjuvant RT, Neo-Adjuvant RT, No RT, histological grade, tumor size, year of diagnosis, and demographic characteristics as covariates.

RESULTS

10-Year CSS estimates were 66.1% (95% CI 62.3-69.6%; P=0.02), 73.5% (95% CI 68.9-77.5%; P=0.02), and 76.1% (95% CI 72.4-79.4%; P=0.02), for No RT, Neo-Adjuvant RT, and Adjuvant RT, respectively. On MVA, Adjuvant RT (HR=0.688; 95% CI, 0.578-0.819; P<0.001) was associated with significantly decreased risk for cancer death. By contrast, Neo-Adjuvant RT was not significantly associated with improved cancer survival (HR=0.863; 95% CI, 0.715-1.043; P=0.127).

CONCLUSION

Adjuvant RT was associated with significantly higher CSS when compared with surgery alone, while the benefit of Neo-Adjuvant RT was not significant. This indicates that surgery followed by Adjuvant RT may still be an important treatment plan for T3N0 rectal cancer with potentially significant survival advantages over other treatment sequences.

Administration of concurrent vaginal brachytherapy during chemotherapy for treatment of endometrial cancer

PURPOSE

To evaluate the tolerability and toxicity of administering vaginal brachytherapy (VB) concurrently during chemotherapy compared with the sequential approach for patients with endometrial cancer.

METHODS AND MATERIALS

A retrospective analysis of 372 surgically staged patients with endometrial cancer American Joint Committee on Cancer 2009 stages I to IV treated with adjuvant postoperative radiation therapy (RT) at our institution from 2001 to 2012 was conducted. All patients received VB+external beam RT (EBRT)+6 cycles of adjuvant carboplatin- and paclitaxel-based chemotherapy. The VB mean dose was 15.08 Gy (range, 15-20 Gy), with 3 to 4 weekly applications, and the EBRT mean dose was 45 Gy delivered with 3-dimensional or intensity modulated RT techniques. Hematologic, gastrointestinal (GI), and genitourinary (GU) toxicities were assessed by Common Toxicity Criteria (CTC) and compared between sequential and concurrent chemotherapy and VB schedules.

RESULTS

Among patients who received RT and adjuvant chemotherapy, 180 of 372 patients (48%) received RT sandwiched between cycles 3 and 4 of chemotherapy. A separate group of 192 patients (52%) were treated with VB during the first 3 cycles of chemotherapy, with a weekly application on nonchemotherapy days, and received the EBRT portion in a sandwiched fashion. Patients treated with VB during chemotherapy had a decreased overall treatment time by 4 weeks (P<.001; 95% confidence interval: 3.99-4.02) and sustained no difference in CTC-graded acute hematologic, GI, or GU toxicities in comparison with the patients treated with VB and chemotherapy in a sequential manner (P>.05). CTC grade 3 or 4 hematologic, GI, and GU toxicities were zero.

CONCLUSIONS

VB during chemotherapy is well tolerated, decreases overall treatment time, and does not render more toxicity than the sequential regimen.

Prostate-specific membrane antigen expression in tumor-associated vasculature of breast cancers

Prostate-specific membrane antigen (PSMA) has been found to be expressed in the tumor-associated neovasculature of multiple solid tumor types including breast cancers. However, thus far, the number of cases studied from some tumor types has been limited. In this study, we set out to assess PSMA expression in the tumor-associated vasculature associated with invasive breast carcinomas in a sizable cohort of patients. One hundred and six patients with AJCC stage 0-IV breast cancer were identified. Ninety-two of these patients had primary breast cancer [invasive breast carcinoma with or without co-existing ductal carcinoma in situ (DCIS) (74) or DCIS alone (18)]. In addition, 14 patients with breast cancer metastases to the brain were identified. Immunohistochemical staining for PSMA and CD31 was performed on parallel representative tumor sections in each case. Tumor-associated vascular endothelial cell PSMA immunoreactivity was semi-quantitatively assessed based on two parameters: overall percent of endothelial positivity and staining intensity. PSMA expression for tumor-associated vascular endothelial cells was scored 0 if there was no detectable PSMA expression, 1 if PSMA staining was detectable in 5-50%, and 2 if PSMA expression was positive in >50% of microvessels. CD 31 staining was concurrently reviewed to confirm the presence of vasculature in each case. Tumor-associated vasculature was PSMA-positive in 68/92 (74%) of primary breast cancers and in 14/14 (100%) of breast cancers metastatic to brain. PSMA was not detected in normal breast tissue or carcinoma cells. All but 2 cases (98%) showed absence of PSMA expression in normal breast tissue-associated vasculature. The 10-year overall survival was 88.7% (95% CI = 80.0%, 93.8%) in patients without brain metastases. When overall survival (OS) was stratified based on PSMA score group, patients with PSMA scores of 0, 1, and 2 had 10-year OS of 95.8%, 96.0%, and 79.7%, respectively (p = 0.12). When PSMA scores of 0 and 1 were compared with 2, there was a statistically significant difference in OS (96.0% vs 79.7%, respectively, p = 0.05). Patients with a PSMA score of 2 had a significantly higher median tumor size compared with patients in the lower PSMA score groups (p = 0.04). Patients with higher nuclear grade were more likely to have a PSMA score of 2 compared with patients with lower nuclear grade (p < 0.0001). Patients with a PSMA score of 2 had a significantly higher median Ki-67 proliferation index compared with patients in the lower PSMA score groups (p < 0.0001). Patients with estrogen receptor (ER)-negative tumors were more likely to have a PSMA score of 2 compared with patients with ER-positive tumors (p < 0.0001). Patients with progesterone receptor (PR)-negative tumors were more likely to have a PSMA score of 2 compared with patients with PR-positive tumors (p = 0.03). No significant association was observed between PSMA score group status and lymph node involvement (p = 0.95). Too little variability was present in Human epidermal growth factor receptor-2 (Her2/neu) amplified tumors to correlate with PSMA score group status. To date, this is the first detailed assessment of PSMA expression in the tumor-associated vasculature of primary and metastatic breast carcinomas. Further studies are needed to evaluate whether PSMA has diagnostic and/or potential therapeutic value.

Stereotactic body radiation therapy (SBRT) for early stage lung cancer delivers clinically significant radiation to the draining lymph nodes

BACKGROUND

To evaluate clinically significant radiotherapy (RT) dose to draining lymph nodes (LN) in patients treated with SBRT.

FINDINGS

Early stage non-small cell lung cancer patients treated with SBRT were selected for analysis. Patients received SBRT if they were not considered eligible for surgical resection. RT plans for 29 patients (32 lesions) were analyzed. For each patient, ipsilateral and contralateral levels 2, 3, 4, 5, 6, 7 and ipsilateral hilar LN stations were contoured. Dose volume histograms and dosimetric coverage of each lymph node region were obtained for each patient. There were 14 males and 15 females. Median age was 75 (range 60-89). Clinically significant RT was received at the corresponding draining lymph node station depending on the primary tumor location. Friedman's non-parametric test revealed a statistically significant difference in RT dose to LN stations depending on the location of the tumor (p<0.0001).

CONCLUSION

SBRT for early stage lung cancer results in significant RT dose to the draining LN. This RT dose may be sufficient to eliminate subclinical microscopic disease despite being a highly conformal treatment. Prospective studies are needed to evaluate if SBRT is comparable to lobectomy plus mediastinal lymph node dissection as a treatment option.

Automatic shape-based level set segmentation for needle tracking in 3-D TRUS-guided prostate brachytherapy

Prostate brachytherapy is an effective treatment for early prostate cancer. The success depends critically on the correct needle implant positions. We have devised an automatic shape-based level set segmentation tool for needle tracking in 3-D transrectal ultrasound (TRUS) images, which uses the shape information and level set technique to localize the needle position and estimate the endpoint of needle in real-time. The 3-D TRUS images used in the evaluation of our tools were obtained using a 2-D TRUS transducer from Ultrasonix (Richmond, BC, Canada) and a computer-controlled stepper motor system from Thorlabs (Newton, NJ, USA). The accuracy and feedback mechanism had been validated using prostate phantoms and compared with 3-D positions of these needles derived from experts' readings. The experts' segmentation of needles from 3-D computed tomography images was the ground truth in this study. The difference between automatic and expert segmentations are within 0.1 mm for 17 of 19 implanted needles. The mean errors of automatic segmentations by comparing with the ground truth are within 0.25 mm. Our automated method allows real-time TRUS-based needle placement difference within one pixel compared with manual expert segmentation.

Predicting the risk of secondary lung malignancies associated with whole-breast radiation therapy

PURPOSE

The risk of secondary lung malignancy (SLM) is a significant concern for women treated with whole-breast radiation therapy after breast-conserving surgery for early-stage breast cancer. In this study, a biologically based secondary malignancy model was used to quantify the risk of secondary lung malignancies (SLMs) associated with several common methods of delivering whole-breast radiation therapy (RT).

METHODS AND MATERIALS

Both supine and prone computed tomography simulations of 15 women with early breast cancer were used to generate standard fractionated and hypofractionated whole-breast RT treatment plans for each patient. Dose-volume histograms (DVHs) of the ipsilateral breast and lung were calculated for each patient on each plan. A model of spontaneous and radiation-induced carcinogenesis was used to determine the relative risks of SLMs for the different treatment techniques.

RESULTS

A higher risk of SLMs was predicted for supine breast irradiation when compared with prone breast irradiation for both the standard fractionation and hypofractionation schedules (relative risk [RR] = 2.59, 95% confidence interval (CI) = 2.30-2.88, and RR = 2.68, 95% CI = 2.39-2.98, respectively). No difference in risk of SLMs was noted between standard fractionation and hypofractionation schedules in either the supine position (RR = 1.05, 95% CI = 0.97-1.14) or the prone position (RR = 1.01, 95% CI = 0.88-1.15).

CONCLUSIONS

Compared with supine whole-breast irradiation, prone breast irradiation is associated with a significantly lower predicted risk of secondary lung malignancy. In this modeling study, fractionation schedule did not have an impact on the risk of SLMs in women treated with whole-breast RT for early breast cancer.

Panoramic cone beam computed tomography

PURPOSE

Cone-beam computed tomography (CBCT) is the main imaging tool for image-guided radiotherapy but its functionality is limited by a small imaging volume and restricted image position (imaged at the central instead of the treatment position for peripheral lesions to avoid collisions). In this paper, the authors present the concept of "panoramic CBCT," which can image patients at the treatment position with an imaging volume as large as practically needed.

METHODS

In this novel panoramic CBCT technique, the target is scanned sequentially from multiple view angles. For each view angle, a half scan (180° + θ(cone) where θ(cone) is the cone angle) is performed with the imaging panel positioned in any location along the beam path. The panoramic projection images of all views for the same gantry angle are then stitched together with the direct image stitching method (i.e., according to the reported imaging position) and full-fan, half-scan CBCT reconstruction is performed using the stitched projection images. To validate this imaging technique, the authors simulated cone-beam projection images of the Mathematical Cardiac Torso (MCAT) thorax phantom for three panoramic views. Gaps, repeated/missing columns, and different exposure levels were introduced between adjacent views to simulate imperfect image stitching due to uncertainties in imaging position or output fluctuation. A modified simultaneous algebraic reconstruction technique (modified SART) was developed to reconstruct CBCT images directly from the stitched projection images. As a gold standard, full-fan, full-scan (360° gantry rotation) CBCT reconstructions were also performed using projection images of one imaging panel large enough to encompass the target. Contrast-to-noise ratio (CNR) and geometric distortion were evaluated to quantify the quality of reconstructed images. Monte Carlo simulations were performed to evaluate the effect of scattering on the image quality and imaging dose for both standard and panoramic CBCT.

RESULTS

Truncated images with artifacts were observed for the CBCT reconstruction using projection images of the central view only. When the image stitching was perfect, complete reconstruction was obtained for the panoramic CBCT using the modified SART with the image quality similar to the gold standard (full-scan, full-fan CBCT using one large imaging panel). Imperfect image stitching, on the other hand, lead to (streak, line, or ring) reconstruction artifacts, reduced CNR, and/or distorted geometry. Results from Monte Carlo simulations showed that, for identical imaging quality, the imaging dose was lower for the panoramic CBCT than that acquired with one large imaging panel. For the same imaging dose, the CNR of the three-view panoramic CBCT was 50% higher than that of the regular CBCT using one big panel.

CONCLUSIONS

The authors have developed a panoramic CBCT technique and demonstrated with simulation data that it can image tumors of any location for patients of any size at the treatment position with comparable or less imaging dose and time. However, the image quality of this CBCT technique is sensitive to the reconstruction artifacts caused by imperfect image stitching. Better algorithms are therefore needed to improve the accuracy of image stitching for panoramic CBCT.

Secondary rectal malignancy risk reduction with IMRT and rectal balloon placement during radiation therapy

e15162

Background: The risk of secondary rectal malignancies (SRMs) is a significant concern following radiation therapy for prostate cancer patients. Modern prostate radiotherapy techniques include the use of intensity modulated radiation therapy (IMRT) and rectal balloons to decrease treatment related toxicity. These technologies may also lower the likelihood of radiation-induced SRMs. In this study, a novel biologically-based carcinogenesis model was used to quantify and to compare the predicted risks of SRMs in men treated with or without a rectal balloon in place using either standard 3-D conformal radiotherapy (3D-CRT) or IMRT radiotherapy. Methods: Treatment plans were developed for ten clinically localized prostate cancer patients using CT scans obtained both with and without a rectal balloon in place. Target and normal structures were contoured, and dose-volume histograms (DVHs) for these organs were determined with a planned 3D-CRT dose of 75.6 Gy or with a planned IMRT dose of 81 Gy. A biologically-based mathematical model of spontaneous and radiation-induced carcinogenesis was used to determine the excess absolute risk of SRMs for each plan. These risks were then compared to one another and to the baseline population. Results: Treatment with IMRT and a rectal balloon in place resulted in a significantly lower mean rectal wall dose in all patients compared with treatment with 3D-CRT without a rectal balloon. The average mean rectal wall dose with IMRT and a rectal balloon in place was 31.0 Gy versus 40.1 Gy with 3D-CRT without the rectal balloon (p < 0.001). A significantly higher risk of SRMs was predicted for patients treated with 3-D CRT without rectal balloons when compared with patients treated with IMRT with balloons in place (p < 0.001, relative risk 1.30; 95% confidence interval 1.16-1.44). Conclusions: For prostate cancer patients treated with definitive radiotherapy, the use of IMRT and rectal balloons during radiation, when compared to treatment with 3-D conformal radiotherapy, is associated with a significant reduction in the predicted risk of secondary rectal malignancies.

Case-control study of prophylactic cranial irradiation in nonmetastatic non-small cell lung cancer

7050

Background: Prophylactic cranial irradiation (PCI) reduces the incidence of brain metastases in NSCLC patients after primary therapy, but its impact on survival is uncertain. We report on the largest study of survival in patients treated with and without PCI for non-small cell lung cancer (NSCLC). Methods: We reviewed 17 Surveillance, Epidemiology and End Results (SEER) registries for a retrospective study on patients who had PCI as part of their primary treatment for NSCLC from 1988 - 97. Cases were limited to those with non-metastatic (Stage I-III) NSCLC. To balance the cohorts, we matched each PCI patient with four non-PCI patients on stage, histology, race and sex. Associations between treatment type, clinical factors, and demographics were assessed using the Chi-squared test. Survival time was calculated as the number of months from diagnosis to the date of death. Survival was censored as of the last month when patients were known to be alive. Overall (OS) and cancer cause-specific survival (CSS) were investigated using the Kaplan-Meier, competing risks, Cox proportional hazards, and log-rank tests. Results: We found 472 PCI matched to 1,888 non-PCI patients. Characteristics were balanced across groups: race (p = 1.00), sex (p = 0.95), histology (p = 1.00), stage (p = 1.00), and surgery (p = 0.81). PCI group was younger, median age 64 vs 68 (p < 0.01). PCI vs no PCI median OS was 8 vs 10 months (p < 0.01). OS was 14% vs 28% at 2 years and 5% vs 12% at 5 years, PCI vs no PCI respectively (p < 0.01). Stage III OS was also different; 10% vs 21% at 2 years, PCI vs no PCI respectively (p < 0.01). Median CSS was the same at 9 months in both groups. Median follow-up was 14 years. Conclusions: PCI was not associated with improved OS or CSS in these NSCLC patients, and PCI may have a detrimental effect on OS. In limited-stage small cell lung cancer, a retrospective SEER analysis during the 1988 – 97 period showed a survival benefit in treated patients with PCI, which has been confirmed with prospective studies. To date, 4 prospective trials examining PCI for NSCLC have shown a reduced incidence of brain metastases, but the effect on survival is unclear. Further investigation is needed to determine whether PCI for NSCLC increases the risk of other causes of death.

Association of IL17-expressing γδ t cells with acute radiation-induced pneumonitis

e21097

Background: Radiation pneumonitis is a substantial cause of morbidity and mortality with thoracic radiation for lung cancer. Little is known about the crucial mechanisms of the inflammatory response. We seek to determine if a key mediator of organ-specific inflammatory disorders and innate immune response, IL-17+ γδ T cells, is associated with radiation pneumonitis. Methods: C3HBe/FeJ mice (7 mice/group) were sham-irradiated as controls or exposed to a single dose of 15 Gy thoracic X-ray to develop pneumonitis. We have previously shown that TGFβ has an immunosuppressive activity in radiation pneumonitis. To potentiate the radiation pneumonitis, one group of mice was administered anti-TGFβ therapy with inhibitory TGFβ mAb (1D11, i.p.10 mg/kg/wk). Bronchoalveolar lavage fluid was assessed for cytology and inflammatory cytokine level. Lung tissues were examined for cell infiltration and histopathological changes. Cell surface marker and intracellular cytokine staining were performed on lymphocytes from the digested lungs by flow cytometry. Results: At 10 weeks post-irradiation, the lungs of the irradiated mice showed substantially more alveolar wall edema and increased infiltration of inflammatory cells compared with sham controls. Pneumonitis-involved lungs contained more IL-17+ γδ T cells (0.85% ± 0.00%) compared with sham controls (0.33% ± 0.02%), p<0.001. Furthermore increased IL-17+ γδ T cells were associated with potentiated radiation pneumonitis with anti-TGFβ therapy. There was a significant increased alveolar inflammation in irradiated mice injected with anti-TGFβ mAb. Anti-TGFβ irradiated lungs also contained significantly more IL-17+ γδ T cells (1.17% ± 0.13%) compared with irradiated controls (0.72% ± 0.13%), p<0.001. There was no increase of other TGFβ-dependent T cell subtypes such as IFNγ+ αβ T cells (Th1), IL-17+ αβ T cells (Th17), CD25+ Foxp3+ Tregs, nor activated macrophages in the potentiated pneumonitis lungs. Conclusions: Our findings implicate a novel role for IL17-expressing γδ T cells in radiation pneumonitis. This study reveals this innate immune response pathway as a potential target for therapeutic intervention in radiation lung injury

Predicting the risk of secondary malignancies associated with stereotactic body radiation therapy

e17562

Background: Treatment of early-stage non-small cell lung cancer (NSCLC) with stereotactic body radiation therapy (SBRT) is associated with high rates of local control and long-term overall survival. With increasing frequency, SBRT is a treatment option for operable tumors which raises the question of the risk of long-term toxicities such as radiation-induced secondary malignancies. There has been no previous risk assessment or epidemiological studies of secondary malignancies with high-dose hypofractionated SBRT. In this study, we seek to quantify the predicted rates of secondary lung malignancies in patients treated with SBRT for stage I-II NSCLC. Methods: Treatment plans for 14 stage I-II NSCLC patients treated with definitive-intent SBRT at Columbia University Medical Center were retrospectively assessed. Median patient age was 73 years (range 54 - 86) with median tumor size of 2.8 cm (range 1.2 - 5.0). SBRT doses ranged from 40-60 Gy in 3-5 fractions. Dose-volume histograms for target PTV and normal lung were generated from planning CT scans. A biologically-based mathematical model of spontaneous and radiation-induced carcinogenesis was used to determine the excess absolute risk and the median lifetime estimated relative risk of secondary lung malignancies for each plan. These risks were then compared using 2-sided t-tests. Results: For all patients, the median lifetime estimated absolute risk of secondary lung malignancy was 1.06% (95% CI 0.62%-1.98%), and the median lifetime estimated relative risk of secondary lung malignancy was 1.61 (95% CI 1.47-1.75) after SBRT. For patients aged less than 65 years, median estimated absolute risk of secondary malignancies was higher (2.8%) than for patients age 65 and older (0.37%), p < 0.001. PTV volume less than 50 cc vs greater than 50 cc, T1 vs T2 tumors, and gender were not significantly associated with differences in estimated absolute risk or estimated relative risk of secondary malignancies. Conclusions: As SBRT is potentially indicated in younger medically operable patients, the long-term late toxicities need to be determined. This study suggests that the risk of second lung malignancies from high-dose SBRT even in younger patients would be minimal.

Small-molecule synthetic compound norcantharidin reverses multi-drug resistance by regulating Sonic hedgehog signaling in human breast cancer cells

Multi-drug resistance (MDR), an unfavorable factor compromising treatment efficacy of anticancer drugs, involves upregulated ATP binding cassette (ABC) transporters and activated Sonic hedgehog (Shh) signaling. By preparing human breast cancer MCF-7 cells resistant to doxorubicin (DOX), we examined the effect and mechanism of norcantharidin (NCTD), a small-molecule synthetic compound, on reversing multidrug resistance. The DOX-prepared MCF-7R cells also possessed resistance to vinorelbine, characteristic of MDR. At suboptimal concentration, NCTD significantly inhibited the viability of DOX-sensitive (MCF-7S) and DOX-resistant (MCF-7R) cells and reversed the resistance to DOX and vinorelbine. NCTD increased the intracellular accumulation of DOX in MCF-7R cells and suppressed the upregulated the mdr-1 mRNA, P-gp and BCRP protein expression, but not the MRP-1. The role of P-gp was strengthened by partial reversal of the DOX and vinorelbine resistance by cyclosporine A. NCTD treatment suppressed the upregulation of Shh expression and nuclear translocation of Gli-1, a hallmark of Shh signaling activation in the resistant clone. Furthermore, the Shh ligand upregulated the expression of P-gp and attenuated the growth inhibitory effect of NCTD. The knockdown of mdr-1 mRNA had not altered the expression of Shh and Smoothened in both MCF-7S and MCF-7R cells. This indicates that the role of Shh signaling in MDR might be upstream to mdr-1/P-gp, and similar effect was shown in breast cancer MDA-MB-231 and BT-474 cells. This study demonstrated that NCTD may overcome multidrug resistance through inhibiting Shh signaling and expression of its downstream mdr-1/P-gp expression in human breast cancer cells.

Adjuvant radiation therapy and survival for pure tubular breast carcinoma--experience from the SEER database

PURPOSE

Pure tubular carcinoma of the breast (PTCB) represents a distinct subtype of invasive ductal carcinoma (IDC) that is generally thought to be associated with better prognosis than even low-grade IDC. There has been controversy as to the role of adjuvant radiation therapy (RT) in this population. We hypothesized that adjuvant RT would demonstrate a survival improvement.

METHODS AND MATERIALS

We queried the Surveillance, Epidemiology and End Results database for the years 1992-2007 to identify patients with pure tubular carcinomas of the breast. Patient demographics, tumor characteristics, and surgical and RT treatments were collected. Survival analysis was performed using the Kaplan-Meier method for univariate comparisons and Cox proportional hazards modeling for multivariate comparisons, stratifying on the basis of age with a cutoff age of 65.

RESULTS

A total of 6465 patients were identified: 3624 (56.1%) patients underwent lumpectomy with RT (LUMP+RT), 1525 (23.6%) patients underwent lumpectomy alone (LUMP), 1266 (19.6%) patients received mastectomy alone (MAST), and 50 (0.8%) patients underwent mastectomy with RT (MAST+RT). When we compared the LUMP+RT and LUMP groups directly, those receiving adjuvant RT tended to be younger and were less likely to be hormone receptor-positive. Overall survival was 95% for LUMP+RT and 90% for LUMP patients at 5 years. For those 65 or younger, the absolute overall survival benefit of LUMP+RT over LUMP was 1% at 5 years and 3% at 10 years. On stratified multivariate analysis, adjuvant RT remained a significant predictor in both age groups (P=.003 in age ≤ 65 and P=.04 in age >65 patients). Other significant unfavorable factors were older age and higher T stage (age >65 only).

CONCLUSIONS

Since sufficiently powered large scale clinical trials are unlikely, we would recommend that adjuvant radiation be considered in PTCB patients age 65 or younger, although consideration of the small absolute survival benefit is important. Adjuvant radiation can be omitted for patients older than 65.

Expression of hedgehog signaling molecules as a prognostic indicator of oral squamous cell carcinoma

BACKGROUND

Recent studies have indicated hedgehog pathway plays a role in carcinogenesis of certain cancers. We investigated the clinical significance of its signaling components, including Sonic hedgehog (Shh), Patched (Ptch), and Gli-1, in oral squamous cell carcinoma (OSCC).

METHODS

By immunohistochemistry, we determined Shh, Ptch, and Gli-1 expression in surgical specimens from 40 patients with OSCC. The relationship between expression of these molecules and clinicopathologic variables were assessed by chi-square analysis. Statistical difference of survival was compared using log-rank test.

RESULTS

Ptch overexpression was associated with lymphatic metastasis (p = .028). Nuclear Gli-1 overexpression correlated with primary tumor size (p = .001), lymphatic metastasis (p = .011), and tumor recurrence (p = .008). Overexpression of Ptch (p = .020) or Gli-1 (p = .002) in OSCC indicated poor prognosis in the univariate survival analysis.

CONCLUSION

Our results suggest sonic hedgehog (Shh) pathway plays an important role in OSCC progression and should be considered a potential therapeutic target.