Simple and effective bacterial-based intratumoral cancer immunotherapy

Background We describe intratumoral injection of a slow-release emulsion of killed mycobacteria (complete Freund’s adjuvant (CFA)) in three preclinical species and in human cancer patients. Methods Efficacy and safety were tested in mammary tumors in mice, in mastocytomas in mice and dogs, and in equine melanomas. In mice, survival, tumor growth, and tumor infiltration by six immune cell subsets (by flow cytometry) were investigated and analyzed using Cox proportional hazards, a random slopes model, and a full factorial model, respectively. Tumor growth and histology were investigated in dogs and horses, as well as survival and tumor immunohistochemistry in dogs. Tumor biopsies were taken from human cancer patients on day 5 (all patients) and day 28 (some patients) of treatment and analyzed by histology. CT scans are provided from one patient. Results Significantly extended survival was observed in mouse P815 and 4T1 tumor models. Complete tumor regressions were observed in all three non-human species (6/186 (3%) of mouse mastocytomas; 3/14 (21%) of canine mastocytomas and 2/11 (18%) of equine melanomas). Evidence of systemic immune responses (regression of non-injected metastases) was also observed. Analysis of immune cells infiltrating mastocytoma tumors in mice showed that early neutrophil infiltration was predictive of treatment benefit. Analysis of the site of mastocytoma regression in dogs weeks or months after treatment demonstrated increased B and T cell infiltrates. Thus, activation of the innate immune system alone may be sufficient for regression of some injected tumors, followed by activation of the acquired immune system which can mediate regression of non-injected metastases. Finally, we report on the use of CFA in 12 human cancer patients. Treatment was well tolerated. CT scans showing tumor regression in a patient with late-stage renal cancer are provided. Conclusion Our data demonstrate that intratumoral injection of CFA has major antitumor effects in a proportion of treated animals and is safe for use in human cancer patients. Further trials in human cancer patients are therefore warranted. Our novel treatment provides a simple and inexpensive cancer immunotherapy, immediately applicable to a wide range of solid tumors, and is suitable to patients in developing countries and advanced care settings.g Canberra trial: Canberra Hospital Private Practice Fund, Janice and Ron Parker Fund. Mouse preclinical studies: Lea Chapuis Memorial Fund. Canine preclinical studies: The John and Mary Kibble Trust (grants CT22492, CT21335) and the William Peter Richards Bequest for research into veterinary pathology. CSEC, ERA, and AAA was supported by Australian Government Research Training Program Stipend Scholarships. CSEC and K-MS were supported by Max Lindemann Memorial Foundation, Miam

How does the gut microbiome influence immune checkpoint blockade therapy?

Immune checkpoint blockade (ICB) therapies are revolutionary cancer treatments; however, they only benefit about a third of patients. Therefore, extensive research is underway to find methods to improve their therapeutic efficacy. One avenue of study that has recently emerged is to consider the role the gut microbiome plays in therapeutic success. Several high-impact studies have repeatedly shown that the presence, composition and level of diversity of the gut flora directly impact cancer treatment outcome in both mice and patients. These studies have also highlighted the danger of using antibiotics shortly before or during cancer treatments. However, there are still several questions that need to be answered, including which bacteria promote the greatest benefit, the mechanisms by which they act and how we can use this information to influence treatment outcome. In this review, we explain how the gut microbiome was realized to be of such importance and propose hypotheses for why gut flora have such a critical impact on ICB therapeutic success. We also describe a hypothetical mechanism involving bacterial translocation out of the gut and into the tumor, whereby the bacteria act in an adjuvant capacity to facilitate an antitumor response. By highlighting key papers in the field, we hope to hasten research on the subject so as to find a means to improve the therapeutic efficacy of these ground-breaking cancer treatments

A novel splicing outcome reveals more than 2000 new mammalian protein isoforms

Motivation: We have recently characterized an instance of alternative splicing that differs from the canonical gene transcript by deletion of a length of sequence not divisible by three, but where translation can be rescued by an alternative start codon

Splice variants of the condensin II gene Ncaph2 include alternative reading frame translations of exon 1

Condensins I and II are five-protein complexes that are important for the condensation of chromatin. They are essential for mitosis and important for regulating gene expression during interphase. Here, we investigated the transcription and translation o

Analysis of A47, an Immunoprevalent Protein of Vaccinia Virus, Leads to a Reevaluation of the Total Antiviral CD8+ T Cell Response▿

Vaccinia virus (VACV) is the prototypic orthopoxvirus and was the live vaccine used to eradicate smallpox. In addition, VACV is a possible vector for recombinant vaccines. Despite these reasons for study, the roles of many VACV genes are unknown, and some fundamental aspects, such as the total size of immune responses, remain poorly characterized. VACV gene A47L is of interest because it is highly transcribed, has no sequence similarity to any nonpoxvirus gene, and contains a larger-than-expected number of CD8+ T cell epitopes. Here it is shown that A47L is not required for growth in vitro and does not contribute to virulence in mice. However, we confirmed that this one protein primes CD8+ T cells to three different epitopes in C57BL/6 mice. In the process, one of these epitopes was redefined and shown to be the most dominant in A47 and one of the more highly ranked in VACV as a whole. The relatively high immunogenicity of this epitope led to a reevaluation of the total CD8+ T cell response to VACV. By the use of two methods, the true size of the response was found to be around double previous estimates and at its peak is on the order of 60% of all CD8+ T cells. We speculate that more CD8+ T cell epitopes remain to be mapped for VACV and that underestimation of responses is unlikely to be unique to VACV, so there would be merit in revisiting this issue for other viruses