The Use of Immunotherapy to Treat Metastatic Breast Cancer

CD44 and RHAMM Are Microenvironmental Sensors with Dual Metastasis Promoter and Suppressor Functions

The progression of primary tumors to metastases remains a significant roadblock to the treatment of most cancers. Emerging evidence has identified genes that specifically affect metastasis and are potential therapeutic targets for managing tumor progression. However, these genes can have dual tumor promoter and suppressor functions that are contextual in manifestation, and that complicate their development as targeted therapies. CD44 and RHAMM/HMMR are examples of multifunctional proteins that can either promote or suppress metastases, as demonstrated in experimental models. These two proteins can be viewed as microenvironmental sensors and this minireview addresses the known mechanistic underpinnings that may determine their metastasis suppressor versus promoter functions. Leveraging this mechanistic knowledge for CD44, RHAMM, and other multifunctional proteins is predicted to improve the precision of therapeutic targeting to achieve more effective management of metastasis.

Experimental and clinical evidence in favour of an effective immune stimulation in ER-positive, endocrine-dependent metastatic breast cancer

In ER+ breast cancer, usually seen as the low immunogenic type, the main mechanisms favouring the immune response or tumour growth and immune evasion in the tumour microenvironment (TME) have been examined. The principal implications of targeting the oestrogen-mediated pathways were also considered. Recent experimental findings point out that anti-oestrogens contribute to the reversion of the immunosuppressive TME. Moreover, some preliminary clinical data with the hormone-immunotherapy association in a metastatic setting support the notion that the reversion of immune suppression in TME is likely favoured by the G0-G1 state induced by anti-oestrogens. Following immune stimulation, the reverted immune suppression allows the boosting of the effector cells of the innate and adaptive immune response. This suggests that ER+ breast cancer is a molecular subtype where a successful active immune manipulation can be attained. If this is confirmed by a prospective multicentre trial, which is expected in light of the provided evidence, the proposed hormone immunotherapy can also be tested in the adjuvant setting. Furthermore, the different rationale suggests a synergistic activity of our proposed immunotherapy with the currently recommended regimen consisting of antioestrogens combined with cyclin kinase inhibitors. Overall, this lays the foundation for a shift in clinical practice within this most prevalent molecular subtype of breast cancer.

RHAMM regulates MMTV-PyMT-induced lung metastasis by connecting STING-dependent DNA damage sensing to interferon/STAT1 pro-apoptosis signaling

BACKGROUND

RHAMM is a multifunctional protein that is upregulated in breast tumors, and the presence of strongly RHAMM+ve cancer cell subsets associates with elevated risk of peripheral metastasis. Experimentally, RHAMM impacts cell cycle progression and cell migration. However, the RHAMM functions that contribute to breast cancer metastasis are poorly understood.

METHODS

We interrogated the metastatic functions of RHAMM using a loss-of-function approach by crossing the MMTV-PyMT mouse model of breast cancer susceptibility with Rhamm-/- mice. In vitro analyses of known RHAMM functions were performed using primary tumor cell cultures and MMTV-PyMT cell lines. Somatic mutations were identified using a mouse genotyping array. RNA-seq was performed to identify transcriptome changes resulting from Rhamm-loss, and SiRNA and CRISPR/Cas9 gene editing was used to establish cause and effect of survival mechanisms in vitro.

RESULTS

Rhamm-loss does not alter initiation or growth of MMTV-PyMT-induced primary tumors but unexpectedly increases lung metastasis. Increased metastatic propensity with Rhamm-loss is not associated with obvious alterations in proliferation, epithelial plasticity, migration, invasion or genomic stability. SNV analyses identify positive selection of Rhamm-/- primary tumor clones that are enriched in lung metastases. Rhamm-/- tumor clones are characterized by an increased ability to survive with ROS-mediated DNA damage, which associates with blunted expression of interferon pathway and target genes, particularly those implicated in DNA damage-resistance. Mechanistic analyses show that ablating RHAMM expression in breast tumor cells by siRNA knockdown or CRISPR-Cas9 gene editing blunts interferon signaling activation by STING agonists and reduces STING agonist-induced apoptosis. The metastasis-specific effect of RHAMM expression-loss is linked to microenvironmental factors unique to tumor-bearing lung tissue, notably high ROS and TGFB levels. These factors promote STING-induced apoptosis of RHAMM+ve tumor cells to a significantly greater extent than RHAMM-ve comparators. As predicted by these results, colony size of Wildtype lung metastases is inversely related to RHAMM expression.

CONCLUSION

RHAMM expression-loss blunts STING-IFN signaling, which offers growth advantages under specific microenvironmental conditions of lung tissue. These results provide mechanistic insight into factors controlling clonal survival/expansion of metastatic colonies and has translational potential for RHAMM expression as a marker of sensitivity to interferon therapy.

Tyrosine Kinase Inhibitors in the Combination Therapy of HER2 Positive Breast Cancer

Human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) accounts for about 20% to 30% of all BC subtypes and is characterized by invasive disease and poor prognosis. With the emergence of anti-HER2 target drugs, HER2-positive BC patient outcomes have changed dramatically. However, treatment failure is mostly due to drug resistance and the special treatment needs of different subgroups. Small molecule tyrosine kinase inhibitors can inhibit multiple targets of the human epidermal growth factor receptor family and activate PI3K/AKT, MAPK, PLC γ, ERK1/2, JAK/STAT, and other pathways affecting the expression of MDM2, mTOR, p27, and other transcription factors. This can help regulate the differentiation, apoptosis, migration, growth, and adhesion of normal cells and reverse drug resistance to a certain extent. These inhibitors can cross the blood-brain barrier and be administered orally. They have a good synergistic effect with effective drugs such as trastuzumab, pertuzumab, t-dm1, and cyclin-dependent kinase 4 and 6 inhibitors. These advantages have resulted in small-molecule tyrosine kinase inhibitors attracting attention. The new small-molecule tyrosine kinase inhibitor was investigated in multi-target anti-HER2 therapy, showed a good effect in preclinical and clinical trials, and to some extent, improved the prognosis of HER2-positive BC patients. Its use could lead to a de-escalation of treatment in some patients, possibly preventing unnecessary procedures along with the associated side effects and costs.

Minimal residual disease in advanced or metastatic solid cancers: The G0-G1 state and immunotherapy are key to unwinding cancer complexity

In the last decade, a large amount of research has focused on elucidating the mechanisms that account for homing disseminated cancer cells (DCCs) from solid tumours to distant organs, which successively progress to overt metastatic disease; this is currently incurable. A better understanding of DCC behaviour is expected to allow detectable metastasis prevention by more effectively targeting 'metastatic seeds before they sprout'. As DCC biology co-evolved with that of the primary tumour, and due to the many similarities between them, the term 'niche' has been borrowed from normal adult stem cells (ASCs) to define the site of DCC metastatic colonisation. Moreover, heterogeneity, survival, protection, stemness and plasticity as well as the prolonged G0-G1 dormant state in the metastatic niche have been the main aspects of intense investigation. Consistent with these findings, in solid cancers with minimal residual disease (MRD), it has been proposed to prolong adjuvant therapy by targeting specific molecular pathway(s) involving DCC dormancy. However, so far, few disappointing clinical data have been reported. As an alternative strategy, because immune-surveillance contributes to the steady state of the DCC population and likely to the G0-G1 state of cancer cells, we have used prolonged immune-modulatory cytostatic chemotherapy, active immune stimulation with an INF-β/IL-2 sequence or drugs inhibiting myeloid-derived suppressor cell (MDSC)/Treg-mediated immune suppression. This strategy, mainly aimed at boosting the immune response, is based on recent findings suggesting the downregulation of immune escape mechanisms as well as other principal hallmarks during the G0-G1 state and/or in MRD. Preliminary clinical and/or laboratory data suggest the efficacy of this strategy in gastrointestinal and some endocrine-dependent cancers. Following this, we propose therapeutic schedules to prevent DCC activation and proliferation in solid cancers at a high risk of relapse or as maintenance therapy in metastatic patients after complete response (CR) to conventional treatment.

Analysis of the Cost-Effectiveness of Liquid Biopsy to Determine Treatment Change in Patients with Her2-Positive Advanced Breast Cancer in Colombia

BACKGROUND

Breast cancer is highly prevalent worldwide and leads to high health-care costs. HER2-positive subtype represents 30% of all breast cancers and is associated with a poor prognosis. Patients treated with anti-HER2 therapies frequently develop resistance and require pharmacological treatment change. Liquid biopsy is a minimally invasive and an easily accessible technique, with high sensitivity and specificity, to detect molecular treatment resistance even before the onset of clinical manifestations and can thus be used to reduce unnecessary anti-HER2 treatment costs.

OBJECTIVE

To evaluate the cost-effectiveness of using liquid biopsy (ctDNA detection) to determine treatment change in women with HER2-positive advanced breast cancer in Colombia.

METHODOLOGY

We performed an economic evaluation using decision tree modeling and deterministic analyses based on literature search for first and second lines of treatment (trastuzumab, pertuzumab, docetaxel, and TDM1); resistance; outcomes; and sensitivity and specificity of tests detecting molecular resistance. The effectiveness was measured using quality-adjusted life year (QALY) score, and costs were obtained from databases with national validity, suppliers, the Colombian Drug Price Information System (SISMED), and local studies.

RESULTS

The use of liquid biopsy (ctDNA detection) with conventional treatment was more expensive and less effective than conventional treatment without liquid biopsy (US $177,985.35 and 0.533889206 QALY, respectively). The incremental cost with liquid biopsy was US $7,333.17 and the incremental effectiveness was 0.00042256 QALY relative to the conventional method.

CONCLUSION

Including liquid biopsy in the treatment of HER2-positive advanced breast cancer was considered currently inapplicable in Colombia because it was not cost effective. Our results open a window of opportunity to improve the development and implementation of ctDNA testing in Colombia, potentially reducing current costs. More evidence is required on the utility of this test, depending on the financial capacity of Colombia and other countries.

Treatment of Metastatic or High-Risk Solid Cancer Patients by Targeting the Immune System and/or Tumor Burden: Six Cases Reports

This article summarizes the histories of six patients with different solid tumors treated with a new strategy based on tumor burden reduction and immune evasion as potential targets. All six patients were at a high risk of relapse and were likely to have a minimal residual disease following conventional therapy: biochemical recurrence (BCR) following radical prostatectomy (RP) (two prostate cancers patients), removal of distant metastases (one colorectal and one breast cancer), and complete response (CR) of distant metastases to conventional therapy (one breast cancer and one esophageal–gastric junction cancer). Four of the patients, two after RP and BCR, one after removal of a single pulmonary metastasis from breast cancer, and one after CR to chemotherapy of peritoneal metastases and ascites from an esophageal–gastric junction primary cancer, regularly received cycles of a new drug schedule with the aim of inhibiting immune suppression (IT). In these four patients, preliminary laboratory tests of peripheral blood suggested an interleukin (IL)-2/IL-12 mediated stimulation of cellular immune response with a concomitant decrease in vascular endothelial growth factor (VEGF) immune suppression. The fifth case was a breast cancer patient with distant metastases in CR, while receiving beta-interferon and interleukin-2 in addition to conventional hormone therapy. To date, all five patients are alive and doing well and they have been unexpectedly disease-free for 201 and 78 months following BCR, 28 months following the removal of a single pulmonary metastases, 32 months following CR to chemotherapy of peritoneal metastases and ascites, and 140 months following diagnosis of multiple bone metastases, respectively. The sixth patient, who had colorectal cancer and multiple synchronous liver metastases and underwent nine surgical interventions for metastatic disease, although not disease-free, is doing well 98 months after primary surgery. Our six cases reports can be interpreted with the hypothesis that immune manipulation and/or a concomitant low tumor burden favored their clinical outcome.

Association analysis of interleukin-18 gene promoter region polymorphisms and susceptibility to sporadic breast cancer in Chinese Han women

BACKGROUND

Interleukin-18-137G/C, -607G/T polymorphisms play multiple roles in various cancers. However, studies focused on its involvement in breast cancer remain controversial, and no study has taken the interaction between interleukin-18 (IL-18) gene polymorphism and body mass index (BMI), menopause into consideration. The study investigated the association between IL-18-137, -607 polymorphisms and risk of breast cancer and a possible interaction between the 2 single nucleotide polymorphisms (SNPs) and BMI, menopause in Chinese Han woman.

METHODS

A total of 488 participants, including 178 patients with breast cancer, 150 patients with benign breast disease and 160 healthy controls were recruited for this study. Polymerase chain reaction (PCR)-direct sequencing technology was used to identify the genotypes.

RESULTS

137 G/C genotype can decrease the risk of breast cancer (OR = 0.54, 95% CI: 0.31-0.93; P = .025). In benign group, subjects with G/C genotype of IL-18-137G/C polymorphism had a 1.89-fold increased risk of developing breast cancer (95% CI = 1.05-3.41; P = .032). Among postmenopausal subjects, people with G/T genotype of IL-18-607 polymorphism had a 7.97-fold increased risk of lymph node metastasis compared with those with T/T homozygotes (95% CI = 1.95-32.65; P = .0045). Among Overweight and obese patients with breast cancer (BMI ≥ 24), people with G/T genotype of IL-18-607 polymorphism had a 5.45-fold increased risk of lymph node metastasis compared with those with T/T homozygotes (95% CI = 1.74-17.06; P = .034).

CONCLUSIONS

IL-18-137 G/C genotype may be a protective factor for healthy group, but a risk factor for benign group. IL-18-607 G/T genotype have an interaction with menopausal and BMI. The synergetic effect can further increase the risk of lymph node metastasis for breast cancer patients.