Listeria delivers tetanus toxoid protein to pancreatic tumors and induces cancer cell death in mice.

Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic disease. Tumors are poorly immunogenic and immunosuppressive, preventing T cell activation in the tumor microenvironment. Here, we present a microbial-based immunotherapeutic treatment for selective delivery of an immunogenic tetanus toxoid protein (TT856-1313) into PDAC tumor cells by attenuated Listeria monocytogenes. This treatment reactivated preexisting TT-specific memory T cells to kill infected tumor cells in mice. Treatment of KrasG12D,p53R172H, Pdx1-Cre (KPC) mice with Listeria-TT resulted in TT accumulation inside tumor cells, attraction of TT-specific memory CD4 T cells to the tumor microenvironment, and production of perforin and granzyme B in tumors. Low doses of gemcitabine (GEM) increased immune effects of Listeria-TT, turning immunologically cold into hot tumors in mice. In vivo depletion of T cells from Listeria-TT + GEM-treated mice demonstrated a CD4 T cell-mediated reduction in tumor burden. CD4 T cells from TT-vaccinated mice were able to kill TT-expressing Panc-02 tumor cells in vitro. In addition, peritumoral lymph node-like structures were observed in close contact with pancreatic tumors in KPC mice treated with Listeria-TT or Listeria-TT + GEM. These structures displayed CD4 and CD8 T cells producing perforin and granzyme B. Whereas CD4 T cells efficiently infiltrated the KPC tumors, CD8 T cells did not. Listeria-TT + GEM treatment of KPC mice with advanced PDAC reduced tumor burden by 80% and metastases by 87% after treatment and increased survival by 40% compared to nontreated mice. These results suggest that Listeria-delivered recall antigens could be an alternative to neoantigen-mediated cancer immunotherapy.

Career planning courses increase career readiness of graduate and postdoctoral trainees.

Background: Given national calls for intentional career development during graduate and post-graduate scientific training, this study assessed career readiness development within the context of academic career courses. The current study evaluated the effects of academic career courses offered at two institutions that were specifically designed to increase career awareness, interest, and career-related confidence among doctoral students and postdoctoral fellows. Methods: Participants enrolled in a career course at trainees' respective academic institutions and responded to pre- and post-course surveys (n=32, n=148). The paper offers a thematic analysis of each of the two courses using an individualized learning plan career development framework and describes the results of their respective pretest-posttest evaluations which indicated increases in career readiness. Results: Though the format and content provided in each course varied, participation was associated with increases in career readiness. Participants reported increased career-awareness including a greater familiarity with different types of careers overall. Furthermore, interest in tenure track faculty careers increased in both samples, which may assuage fears that exposure to diverse career pathways could reduce interest in academic careers. Transferrable skills, including career planning and awareness also significantly increased. Course participants reported an increase in the number and type of mentors they interacted with beyond their principal faculty mentor (other faculty, professional PhDs, peers, and administrative staff). Conclusions: Findings provide supporting evidence for the benefits of implementing structured career development efforts during PhD training; even with varying content, delivery methods, and instructor type, both academic career courses led to significant gains in career awareness and readiness. Successful development and delivery of academic career courses, with a focus on career planning skills, suggest that institutions can utilize these and are an effective way to prepare PhDs for their transition from training positions into careers.

Immunotherapy with Listeria reduces metastatic breast cancer in young and old mice through different mechanisms.

Cancer immunotherapy is one of the most promising and benign therapies against metastatic cancer. However, most cancer patients are old and elderly react less efficient to cancer vaccines than young adults, due to T cell unresponsiveness. Here we present data of cancer vaccination in young and old mice with metastatic breast cancer (4T1 model). We tested adaptive and innate immune responses to foreign antigens (Listeria-derived) and self-antigens (tumor-associated antigens (TAA)) and their contribution to elimination of metastases at young and old age. Three different protocols were tested with Listeria: a semi- and exclusive-therapeutic protocol both one-week apart, and an exclusive therapeutic protocol frequently administered. Adaptive and innate immune responses were measured by ELISPOT in correlation with efficacy in the 4T1 model. We found that Listeria induced immunogenic tumor cell death, resulting in CD8 T cell responses to multiple TAA expressed by the 4T1 tumors. Only exclusive therapeutic frequent immunizations were able to overcome immune suppression and to activate TAA- and Listeria-specific CD8 T cells, in correlation with a strong reduction in metastases at both ages. However, MHC class Ia antibodies showed inhibition of CD8 T cell responses to TAA at young but not at old age, and CD8 T cell depletions in vivo demonstrated that the T cells contributed to reduction in metastases at young age only. These results indicate that CD8 T cells activated by Listeria has an antitumor effect at young but not at old age, and that metastases at old age have been eliminated through different mechanism(s).

Cryoablation and Meriva have strong therapeutic effect on triple-negative breast cancer.

Interleukin-6, a cytokine produced particularly by triple-negative breast cancers, strongly inhibits T cell responses in the tumor microenvironment. Here we tested cryoablation combined with Meriva (a lecithin delivery system of curcumin with improved bioavailability) in mice with metastatic breast cancer (4T1). Cryoablation involves killing of tumor cells through freezing and thawing, resulting in recruitment of tumor-specific T cells, while curcumin stimulates T cells through the reduction of IL-6 in the TME. Cryoablation plus Meriva accumulated and activated CD8+ T cells to multiple tumor-associated antigens such as Mage-b and Survivin (both expressed by 4T1 tumors). This correlated with a nearly complete reduction of 4T1 primary tumors and lung metastases while little effect was observed from saline or Meriva alone (28 d after tumor cell injection). The survival rate in the group of cryoablation plus Meriva was significantly improved compared to all control groups. Using a less aggressive 4T1 model expressing luciferase (4T1.2luc3), we demonstrated that all mice receiving saline or Meriva developed metastases in the lungs and a primary tumor (38 d after tumor cell injection; and died soon after that), but not the mice receiving cryoablation or cryoablation plus Meriva. However, on day 58 the mice receiving cryoablation developed 4T1.2luc3 metastases in the lungs, while mice receiving cryoablation plus Meriva were free of metastases. These results strongly suggest that cryoablation delayed the development of lung metastases on the short-term, but Meriva administered after cryoablation was significantly better in delaying the development of lung metastases and survival on the long-term.

STING ligand c-di-GMP improves cancer vaccination against metastatic breast cancer.

Cancer vaccination may be our best and most benign option for preventing or treating metastatic cancer. However, breakthroughs are hampered by immune suppression in the tumor microenvironment. In this study, we analyzed whether cyclic diguanylate (c-di-GMP), a ligand for stimulator of interferon genes (STING), could overcome immune suppression and improve vaccination against metastatic breast cancer. Mice with metastatic breast cancer (4T1 model) were therapeutically immunized with an attenuated Listeria monocytogenes (LM)-based vaccine, expressing tumor-associated antigen Mage-b (LM-Mb), followed by multiple low doses of c-di-GMP (0.2 µmol/L). This treatment resulted in a striking and near elimination of all metastases. Experiments revealed that c-di-GMP targets myeloid-derived suppressor cells (MDSC) and tumor cells. Low doses of c-di-GMP significantly increased the production of IL12 by MDSCs, in correlation with improved T-cell responses to Mage-b, whereas a high dose of c-di-GMP (range, 0.3-3 mmol/L) activated caspase-3 in the 4T1 tumor cells and killed the tumor cells directly. On the basis of these results, we tested one administration of high-dose c-di-GMP (3 mmol/L) followed by repeated administrations of low-dose c-di-GMP (0.2 µmol/L) in the 4T1 model, and found equal efficacy compared with the combination of LM-Mb and c-di-GMP. This finding correlated with a mechanism of improved CD8 T-cell responses to tumor-associated antigens (TAA) Mage-b and Survivin, most likely through cross-presentation of these TAAs from c-di-GMP-killed 4T1 tumor cells, and through c-di-GMP-activated TAA-specific T cells. Our results demonstrate that activation of STING-dependent pathways by c-di-GMP is highly attractive for cancer immunotherapy.

Is cancer vaccination feasible at older age?

Age-related defects of the immune system are responsible for T cell unresponsiveness to cancer vaccination at older age. Major immune defects at older age are lack of naive T cells, impaired activation pathways of T cells and antigen-presenting cells (APCs), and age-related changes in the tumor microenvironment (TME). This raises the question whether cancer vaccination is feasible at older age. We compared various cancer vaccine studies at young and old age, thereby focusing on the importance of both innate and adaptive immune responses for cancer immunotherapy. These analyses suggest that creating an immune-stimulating environment with help of the innate immune system may improve T cell responses in cancer vaccination at older age.

Curcumin improves the therapeutic efficacy of Listeria(at)-Mage-b vaccine in correlation with improved T-cell responses in blood of a triple-negative breast cancer model 4T1.

Success of cancer vaccination is strongly hampered by immune suppression in the tumor microenvironment (TME). Interleukin (IL)-6 is particularly and highly produced by triple-negative breast cancer (TNBC) cells, and has been considered as an important contributor to immune suppression in the TME. Therefore, we hypothesized that IL-6 reduction may improve efficacy of vaccination against TNBC cancer through improved T-cell responses. To prove this hypothesis, we investigated the effect of curcumin, an inhibitor of IL-6 production, on vaccination of a highly attenuated Listeria monocytogenes (Listeria(at)), encoding tumor-associated antigens (TAA) Mage-b in a TNBC model 4T1. Two therapeutic vaccination strategies with Listeria(at)-Mage-b and curcumin were tested. The first immunization strategy involved all Listeria(at)-Mage-b vaccinations and curcumin after tumor development. As curcumin has been consumed all over the world, the second immunization strategy involved curcumin before and all therapeutic vaccinations with Listeria(at)-Mage-b after tumor development. Here, we demonstrate that curcumin significantly improves therapeutic efficacy of Listeria(at)-Mage-b with both immunization strategies particularly against metastases in a TNBC model (4T1). The combination therapy was slightly but significantly more effective against the metastases when curcumin was administered before compared to after tumor development. With curcumin before tumor development in the combination therapy, the production of IL-6 was significantly decreased and IL-12 increased by myeloid-derived suppressor cells (MDSC), in correlation with improved CD4 and CD8 T-cell responses in blood. Our study suggests that curcumin improves the efficacy of Listeria(at)-Mage-b vaccine against metastases in TNBC model 4T1 through reversal of tumor-induced immune suppression.

Nontoxic radioactive Listeria(at) is a highly effective therapy against metastatic pancreatic cancer.

No significant improvement in therapy of pancreatic cancer has been reported over the last 25 y, underscoring the urgent need for new alternative therapies. Here, we coupled a radioisotope, (188)Rhenium, to an attenuated (at) live Listeria monocytogenes (Listeria(at)) using Listeria-binding antibodies, thus creating a unique radioactive Listeria(at) (RL). We then demonstrated in a highly metastatic pancreatic mouse tumor model (Panc-02) that RL delivered radioactivity to the metastases and less abundantly to primary tumors in vivo, without harming normal cells. This result was possible because Listeria(at) was efficiently cleared by the immune system in normal tissues but not in the heavily immune-suppressed microenvironment of metastases and primary tumor. Multiple treatments with low doses of the RL resulted in a dramatic decrease in the number of metastases (~90%) compared with control groups in the Panc-02 model. This is the first report of using live attenuated bacteria delivering a highly radioactive payload to the metastases, resulting in killing tumor cells in vivo without harming normal cells. The nontoxic RL treatment is attractive for clinical development as a therapy to prevent pancreatic cancer recurrence and metastases.

Mutational analysis of HOXA2 and SIX2 in a Bronx population with isolated microtia.

OBJECTIVE: Microtia is a developmental malformation of the external ear with genetic and environmental causes. The prevalence of microtia varies but several studies suggest increased incidence in Hispanic and African American populations. No causal genetic mutations have been identified in these populations. Mutations in the homeobox gene HOXA2 caused microtia in a single Iranian family. Another homeobox gene, SIX2, acts downstream of HOXA2 during development and provides another possible candidate for mutational analysis. METHODS: To determine whether mutations in HOXA2 or SIX2 cause sporadic microtia, DNA sequencing analysis was performed on exons in both genes in 8 patients of Hispanic and African descent in the Bronx. Identified variants were assayed in an additional 4 patients and 100 Hispanic control samples using Sequenom MassArray to rule out causality in heterozygous patients. RESULTS: No mutations were identified in the coding sequence of HOXA2 or SIX2. Four novel single nucleotide variants were identified among the patient samples. These variants lie in the intron and 3' UTR of HOXA2 and the 5' and 3' UTRs of SIX2. One variant in the intron of HOXA2 lies in a conserved predicted transcription factor binding site for SMARCA3. All four variants are also present at >5% frequency in Hispanic control samples, ruling out these novel variations as causal. CONCLUSIONS: Lack of mutations in the coding regions of HOXA2 or SIX2 among the sporadic microtia patients studied indicate different etiologies. Identification of four novel single nucleotide polymorphisms in patients and controls of Hispanic descent, but not of Caucasian populations, points to genetic diversity in an understudied population.