Class IIa HDAC inhibition reduces breast tumours and metastases through anti-tumour macrophages.

Although the main focus of immuno-oncology has been manipulating the adaptive immune system, harnessing both the innate and adaptive arms of the immune system might produce superior tumour reduction and elimination. Tumour-associated macrophages often have net pro-tumour effects, but their embedded location and their untapped potential provide impetus to discover strategies to turn them against tumours. Strategies that deplete (anti-CSF-1 antibodies and CSF-1R inhibition) or stimulate (agonistic anti-CD40 or inhibitory anti-CD47 antibodies) tumour-associated macrophages have had some success. We hypothesized that pharmacologic modulation of macrophage phenotype could produce an anti-tumour effect. We previously reported that a first-in-class selective class IIa histone deacetylase (HDAC) inhibitor, TMP195, influenced human monocyte responses to the colony-stimulating factors CSF-1 and CSF-2 in vitro. Here, we utilize a macrophage-dependent autochthonous mouse model of breast cancer to demonstrate that in vivo TMP195 treatment alters the tumour microenvironment and reduces tumour burden and pulmonary metastases by modulating macrophage phenotypes. TMP195 induces the recruitment and differentiation of highly phagocytic and stimulatory macrophages within tumours. Furthermore, combining TMP195 with chemotherapy regimens or T-cell checkpoint blockade in this model significantly enhances the durability of tumour reduction. These data introduce class IIa HDAC inhibition as a means to harness the anti-tumour potential of macrophages to enhance cancer therapy.

Comparing syngeneic and autochthonous models of breast cancer to identify tumor immune components that correlate with response to immunotherapy in breast cancer.

BACKGROUND: The heterogeneity of the breast tumor microenvironment (TME) may contribute to the lack of durable responses to immune checkpoint blockade (ICB); however, mouse models to test this are currently lacking. Proper selection and use of preclinical models are necessary for rigorous, preclinical studies to rapidly move laboratory findings into the clinic. METHODS: Three versions of a common syngeneic model derived from the MMTV-PyMT autochthonous model were generated by inoculating 1E6, 1E5, or 1E4 cells derived from the MMTV-PyMT mouse into wildtype recipient mice. To elucidate how tumor latency and TME heterogeneity contribute to ICB resistance, comprehensive characterization of the TME using quantitative flow-cytometry and RNA expression analysis (NanoString) was performed. Subsequently, response to ICB was tested. These procedures were repeated using the EMT6 breast cancer model. RESULTS: The 3 syngeneic versions of the MMTV-PyMT model had vastly different TMEs that correlated to ICB response. The number of cells used to generate syngeneic tumors significantly influenced tumor latency, infiltrating leukocyte populations, and response to ICB. These results were confirmed using the EMT6 breast cancer model. Compared to the MMTV-PyMT autochthonous model, all 3 MMTV-PyMT syngeneic models had significantly more tumor-infiltrating lymphocytes (TILs; CD3+, CD4+, and CD8+) and higher proportions of PD-L1-positive myeloid cells, whereas the MMTV-PyMT autochthonous model had the highest frequency of myeloid cells out of total leukocytes. Increased TILs correlated with response to anti-PD-L1 and anti-CTLA-4 therapy, but PD-L1expression on tumor cells or PD-1 expression of T cells did not. CONCLUSIONS: These studies reveal that tumor cell number correlates with tumor latency, TME, and response to ICB. ICB-sensitive and resistant syngeneic breast cancer models were identified, in which the 1E4 syngeneic model was most resistant to ICB. Given the lack of benefit from ICB in breast cancer, identifying robust murine models presented here provides the opportunity to further interrogate the TME for breast cancer treatment and provide novel insights into therapeutic combinations to overcome ICB resistance.

Gender differences in NIH grant funding in neurological surgery.

Research productivity is a vital component to an academic neurosurgeon's career. We sought to evaluate gender differences in NIH funding among faculty in neurological surgery departments. NIH funding awarded to PIs of neurological surgery departments from 2014 to 2019 were obtained and analyzed for gender differences in funding trends, with attention to terminal degree and academic rank, as well as publication range in length of years and h-index. 79.4% of all NIH grants were awarded to male PIs, with the remaining 20.5% given to their female counterparts. Mean of the total NIH grants awarded to men was significantly higher at $1,796,684 (± Standard Error of Mean (SEM) $155,849, IQR: $1,759,250) compared to women at $1,151,968 (± SEM $137,914, IQR: $1,388,538) (P = 0.022). Mean NIH funding per grant for men was $365,760 (± SEM: $39,592, IQR: $189,692) and for women was $292,912 (± SEM: 28,239, IQR: $283,177). Differences in mean NIH funding per grant approached but did not reach statistical significance between men and women (P = 0.122). When stratified for academic rank, there was a significant difference in mean NIH funding per grant between men and women on the associate professor level (p < 0.005), with women exceeding men in funding at this academic level, with other academic ranks remaining non-significant. Overall, male neurosurgeons receive significantly more total NIH grant funding than their female counterparts, except at the level of associate professor where women were found to surpass men.

High-throughput dynamic BH3 profiling may quickly and accurately predict effective therapies in solid tumors.

Despite decades of effort, the sensitivity of patient tumors to individual drugs is often not predictable on the basis of molecular markers alone. Therefore, unbiased, high-throughput approaches to match patient tumors to effective drugs, without requiring a priori molecular hypotheses, are critically needed. Here, we improved upon a method that we previously reported and developed called high-throughput dynamic BH3 profiling (HT-DBP). HT-DBP is a microscopy-based, single-cell resolution assay that enables chemical screens of hundreds to thousands of candidate drugs on freshly isolated tumor cells. The method identifies chemical inducers of mitochondrial apoptotic signaling, a mechanism of cell death. HT-DBP requires only 24 hours of ex vivo culture, which enables a more immediate study of fresh primary tumor cells and minimizes adaptive changes that occur with prolonged ex vivo culture. Effective compounds identified by HT-DBP induced tumor regression in genetically engineered and patient-derived xenograft (PDX) models of breast cancer. We additionally found that chemical vulnerabilities changed as cancer cells expanded ex vivo. Furthermore, using PDX models of colon cancer and resected tumors from colon cancer patients, our data demonstrated that HT-DBP could be used to generate personalized pharmacotypes. Thus, HT-DBP appears to be an ex vivo functional method with sufficient scale to simultaneously function as a companion diagnostic, therapeutic personalization, and discovery tool.

Female Medical Student Retention in Neurosurgery: A Multifaceted Approach.

BACKGROUND: Since 2011, more women than men have graduated from medical school, yet there remains a paucity of female physicians in surgical specialties. After the 2018 Neurosurgery Match, only 17.5% of neurosurgery residents are women. Previous literature documented gender inequality, poor medical school exposure, and lack of female mentorship as reasons for this disparity. We sought to further explore factors that deter female medical students from pursuing neurosurgery. METHODS: A comprehensive survey was created and distributed to the 2017-2018 Rutgers New Jersey Medical School student body, requesting anonymous input from female medical students. RESULTS: Of 104 female respondents, 26.9% had considered neurosurgery as a career and felt dissuaded because of their gender. Of respondents, 88% did not have a senior female medical student pursuing neurosurgery or a female neurosurgical resident as a mentor. More than half of respondents disagreed that they would be dissuaded from a field if they did not have a female mentor. The 88.46% of women who felt that there was a glass ceiling in medicine were also more likely to feel that they would face inequality and adversity that would inhibit training in a male-dominated field. Women who described themselves as seeking challenging and competitive careers strongly felt that they would benefit from exposure to surgical subspecialties during their preclinical years. CONCLUSIONS: Female medical students remain resilient, ambitious, interested in competitive specialties, and eager to explore surgical subspecialties during preclinical years. A multifaceted approach is imperative to recruit and retain qualified women interested in neurosurgery.

Gender Representation at Neurological Surgery Conferences.

BACKGROUND: Women constitute a minority (9.2%) of academic neurosurgeons. We previously found that women in academic medicine are disadvantaged in funding and career advancement opportunities. We hypothesized that women are also underrepresented at neurosurgical society conferences. METHODS: Programs from the 2014-2018 meetings of the Congress of Neurological Surgeons (CNS), American Association of Neurological Surgery (AANS), and North American Skull Base Society (NASBS) were analyzed. Demographic data, including name, gender, and geographic region of practice, were collected for speaker, moderator, or leadership positions. χ2 statistical analysis was performed for difference in gender representation across all opportunity spots. RESULTS: In the period 2014-2018, there was no female presidents or honored guest at any academic meetings analyzed; 53.8% of executive committees comprised all men. Women often constituted a minority (<15%) of speakers and moderators at CNS, AANS, and NASBS meetings: speakers (% female, range), 8.6 (5.5-11.7), 13.6 (10.1-19.7), and 10.5 (5.6-16.6); moderators (% female, range), 7.8 (0-14.3), 23.0 (81.3-91.3), and 13.0 (8.6-18.7). Conference panels frequently comprised all men (58% CNS, 20.7% AANS, 61% NASBS). χ2 analysis found a disparity in male and female participation across all opportunity spots (P = 0.002). Additionally, female participants are often repeated, decreasing total number of unique women participating. There was no significant increase in female participation across the study period. CONCLUSIONS: In 2014-2018, underrepresentation of women in national neurosurgical conferences either matched or exceeded the baseline gender disparity seen in academic neurosurgery. We discussed potential causes of and strategies to address these findings.

Proximodistal Heterogeneity of Hippocampal CA3 Pyramidal Neuron Intrinsic Properties, Connectivity, and Reactivation during Memory Recall.

The hippocampal CA3 region is classically viewed as a homogeneous autoassociative network critical for associative memory and pattern completion. However, recent evidence has demonstrated a striking heterogeneity along the transverse, or proximodistal, axis of CA3 in spatial encoding and memory. Here we report the presence of striking proximodistal gradients in intrinsic membrane properties and synaptic connectivity for dorsal CA3. A decreasing gradient of mossy fiber synaptic strength along the proximodistal axis is mirrored by an increasing gradient of direct synaptic excitation from entorhinal cortex. Furthermore, we uncovered a nonuniform pattern of reactivation of fear memory traces, with the most robust reactivation during memory retrieval occurring in mid-CA3 (CA3b), the region showing the strongest net recurrent excitation. Our results suggest that heterogeneity in both intrinsic properties and synaptic connectivity may contribute to the distinct spatial encoding and behavioral role of CA3 subregions along the proximodistal axis.

Dendritic Na+ spikes enable cortical input to drive action potential output from hippocampal CA2 pyramidal neurons.

Synaptic inputs from different brain areas are often targeted to distinct regions of neuronal dendritic arbors. Inputs to proximal dendrites usually produce large somatic EPSPs that efficiently trigger action potential (AP) output, whereas inputs to distal dendrites are greatly attenuated and may largely modulate AP output. In contrast to most other cortical and hippocampal neurons, hippocampal CA2 pyramidal neurons show unusually strong excitation by their distal dendritic inputs from entorhinal cortex (EC). In this study, we demonstrate that the ability of these EC inputs to drive CA2 AP output requires the firing of local dendritic Na+ spikes. Furthermore, we find that CA2 dendritic geometry contributes to the efficient coupling of dendritic Na+ spikes to AP output. These results provide a striking example of how dendritic spikes enable direct cortical inputs to overcome unfavorable distal synaptic locale to trigger axonal AP output and thereby enable efficient cortico-hippocampal information flow.