Minimally invasive assessment of tumor angiogenesis by fine needle aspiration and flow cytometry

NP-ALT, a Liposomal:Peptide Drug, Blocks p27Kip1 Phosphorylation to Induce Oxidative Stress, Necroptosis, and Regression in Therapy-Resistant Breast Cancer Cells

Resistance to cyclin D-CDK4/6 inhibitors (CDK4/6i) represents an unmet clinical need and is frequently caused by compensatory CDK2 activity. Here we describe a novel strategy to prevent CDK4i resistance by using a therapeutic liposomal:peptide formulation, NP-ALT, to inhibit the tyrosine phosphorylation of p27Kip1(CDKN1B), which in turn inhibits both CDK4/6 and CDK2. We find that NP-ALT blocks proliferation in HR+ breast cancer cells, as well as CDK4i-resistant cell types, including triple negative breast cancer (TNBC). The peptide ALT is not as stable in primary mammary epithelium, suggesting that NP-ALT has little effect in nontumor tissues. In HR+ breast cancer cells specifically, NP-ALT treatment induces ROS and RIPK1-dependent necroptosis. Estrogen signaling and ERα appear required. Significantly, NP-ALT induces necroptosis in MCF7 ESR^Y537S cells, which contain an ER gain of function mutation frequently detected in metastatic patients, which renders them resistant to endocrine therapy. Here we show that NP-ALT causes necroptosis and tumor regression in treatment naïve, palbociclib-resistant, and endocrine-resistant BC cells and xenograft models, demonstrating that p27 is a viable therapeutic target to combat drug resistance. IMPLICATIONS: This study reveals that blocking p27 tyrosine phosphorylation inhibits CDK4 and CDK2 activity and induces ROS-dependent necroptosis, suggesting a novel therapeutic option for endocrine and CDK4 inhibitor-resistant HR+ tumors.

Novel non-terminal tumor sampling procedure using fine needle aspiration supports immuno-oncology biomarker discovery in preclinical mouse models

Background

Immuno-oncology therapies are now part of the standard of care for cancer in many indications. However, durable objective responses remain limited to a subset of patients. As such, there is a critical need to identify biomarkers that can predict or enrich for treatment response. So far, the majority of putative biomarkers consist of features of the tumor microenvironment (TME). However, in preclinical mouse models, the collection of tumor tissue for this type of analysis is a terminal procedure, obviating the ability to directly link potential biomarkers to long-term treatment outcomes.

Methods

To address this, we developed and validated a novel non-terminal tumor sampling method to enable biopsy of the TME in mouse models based on fine needle aspiration.

Results

We show that this technique enables repeated in-life sampling of subcutaneous flank tumors and yields sufficient material to support downstream analyses of tumor-infiltrating immune cells using methods such as flow cytometry and single-cell transcriptomics. Moreover, using this technique we demonstrate that we can link TME biomarkers to treatment response outcomes, which is not possible using the current method of terminal tumor sampling.

Conclusion

Thus, this minimally invasive technique is an important refinement for the pharmacodynamic analysis of the TME facilitating paired evaluation of treatment response biomarkers with outcomes and reducing the number of animals used in preclinical research.

Depletion of phagocytic myeloid cells triggers spontaneous T cell- and NK cell-dependent antitumor activity

Depletion of tumor associated macrophages and inhibition of tumor angiogenesis have been invoked as the principle mechanisms underlying the antitumor activity of liposomal clodronate (LC). However, previous studies have not examined the effects of LC on systemic antitumor immunity. Here, we used mouse tumor models to elucidate the role of T and NK cells in the antitumor activity elicited by the systemic administration of LC. Strikingly, we found that the antitumor activity of LC is completely abolished in immunodeficient Rag1^−/− mice. Moreover, both Cd4^−/− and Cd8^−/− mice as well as mice depleted of NK cells manifested a significant impaired ability to control tumor growth following LC administration. Treatment with LC did not result in an overall increase in T- or NK-cell numbers in tumors or lymphoid organs, nor was tumor infiltration with T or NK cells altered. However, T and NK cells isolated from the spleen of LC-treated mice exhibited significant increased tumor-specific secretion of interferon γ and interleukin 17 and greater cytolytic activity. We concluded that the antitumor effects of LC are largely dependent on the generation of systemic T-cell and NK- cell activity, most likely owing to the depletion of immune suppressive myeloid cell populations in lymphoid tissues. These findings suggest that the systemic administration of LC may constitute an effective means for non-specifically augmenting the antitumor activity of T and NK cells.

Preclinical evaluation of PSMA expression in response to androgen receptor blockade for theranostics in prostate cancer

Background

Prostate-specific membrane antigen (PSMA)-directed radioligand therapy (RLT) is a promising yet not curative approach in castration-resistant (CR) prostate cancer (PC). Rational combination therapies may improve treatment efficacy. Here, we explored the effect of androgen receptor blockade (ARB) on PSMA expression visualized by PET and its potential additive effect when combined with ¹⁷⁷Lu-PSMA RLT in a mouse model of prostate cancer.

Methods

Mice bearing human CRPC (C4-2 cells) xenografts were treated with 10 mg/kg enzalutamide (ENZ), with 50 mg/kg bicalutamide (BIC), or vehicle (control) for 21 days. PSMA expression was evaluated by ⁶⁸Ga-PSMA11 PET/CT and quantified by flow cytometry of tumor fine needle aspirations before treatment and on days 23, 29, 34, and 39 post-therapy induction. For the RLT combination approach, mice bearing C4-2 tumors were treated with 10 mg/kg ENZ or vehicle for 21 days before receiving either 15 MBq (84 GBq/μmol) ¹⁷⁷Lu-PSMA617 or vehicle. DNA damage was assessed as phospho-γH2A.X foci in tumor biopsies. Reduction of tumor volume on CT and survival were used as study endpoints.

Results

Tumor growth was delayed by ARB while ⁶⁸Ga-PSMA11 uptake increased up to 2.3-fold over time when compared to controls. ABR-induced upregulation of PSMA expression was confirmed by flow cytometry. Phospho-γH2A.X levels increased 1.8- and 3.4-fold at 48 h in response to single treatment ENZ or RLT and ENZ+RLT, respectively. Despite significantly greater DNA damage and persistent increase of PSMA expression at the time of RLT, no additional tumor growth retardation was observed in the ENZ+RLT group (vs. RLT only, p = 0.372 at day 81). Median survival did not improve significantly when ENZ was combined with RLT.

Conclusion

ARB-mediated increases in PSMA expression in PC xenografts were evident by ⁶⁸Ga-PSMA11 PET imaging and flow cytometry. ¹⁷⁷Lu-PSMA617 effectively decreased C4-2 tumor size. However, while pre-treatment with ARB increased DNA damage significantly, it did not result in synergistic effects when combined with RLT.

Electronic supplementary material

The online version of this article (10.1186/s13550-018-0451-z) contains supplementary material, which is available to authorized users.

Repeated fine-needle aspiration of solid tumours in mice allows the identification of multiple infiltrating immune cell types

This paper describes a novel method for following the changes in mouse tumour-infiltrating immune cell populations by repeated sampling of tumours by fine needle aspiration (FNA), followed by flow cytometry. Using this technique we were able to collect samples from P815 mouse mastocytomas, and identify and enumerate six tumour-infiltrating immune cell types at multiple time points for each mouse. We demonstrate good agreement between cell percentages obtained from FNA samples and matched whole tumour digests (WTDs). We also demonstrate that neither survival nor the incidence of liver metastasis is adversely affected by the procedure. Our method has a clear advantage over the common practice of sacrificing mice and collecting tissue at pre-determined time points, as the technique allows 1) repeated sampling of each mouse over time, thus many fewer mice are required, and 2) the correlation of survival data with tumour-infiltrating immune cell types at different time points. This potentially allows immune cell types associated with increased or decreased survival to be identified. Therefore, our technique should greatly facilitate the characterisation of anti-tumour immunity induced in response to cancer therapy in small animal models.

Fine needle aspiration: an atraumatic method to diagnose head and neck masses

BACKGROUND

Patients presenting with a mass require tissue biopsy for histological diagnosis and treatment. Fine needle aspiration (FNA) is offered as an atraumatic, well tolerated, and inexpensive method for obtaining a biopsy from these lesions.

OBJECTIVES

In this study we evaluated the accuracy of FNA as an atraumatic method among patients with nonthyroidal masses for diagnosis of neoplastic masses compared to open surgery.

PATIENTS AND METHODS

In a cross-sectional study, 65 patients with a head and neck masses (nonthyroidal) referred to us from 2004 to 2009. Those who had both FNA and open biopsy (the gold standard) were assessed for specificity, sensitivity, positive and negative predictive values of FNA in diagnoses.

RESULTS

Sixty-five cases with both definite diagnoses of open biopsy and FNA were assessed. The mean (± standard deviation) age of patients was 39.96 ± 19.69 years (range 10 to 82 years). Twenty-five (40.8%) subjects were categorized as malignant neoplasms, 16 (19.4%) as benign neoplasms, and 24 (39.8%) as non-neoplastic lesions. The sensitivity, specificity, positive and also negative predictive values of FNA in the diagnosis of neoplastic masses were 95%, 85%, 92.68%, and 91.66% respectively, and the diagnostic accuracy was 92.3%.

CONCLUSIONS

It seems that FNA is a useful atraumatic diagnostic technique with a high diagnostic accuracy which can provide a highly sensitive diagnosis with low false positive diagnoses in patients with nonthyroidal masses.

Modeling the inhibition of breast cancer growth by GM-CSF

M-CSF is overexpressed in breast cancer and is known to stimulate macrophages to produce VEGF resulting in angiogenesis. It has recently been shown that the growth factor GM-CSF injected into murine breast tumors slowed tumor growth by secreting soluble VEGF receptor-1 (sVEGFR-1) that binds and inactivates VEGF. This study presents a mathematical model that includes all the components above, as well as MCP-1, tumor cells, and oxygen. The model simulations are representative of the in vivo data through predictions of tumor growth using different protocol strategies for GM-CSF for the purpose of predicting higher degrees of treatment success. For example, our model predicts that once a week dosing of GM-CSF would be less effective than daily, twice a week, or three times a week treatment because of the presence of essential factors required for the anti-tumor effect of GM-CSF.