Pembrolizumab: PD-1 inhibition as a therapeutic strategy in cancer

New Developments in Breast Cancer and Their Impact on Daily Practice in Pathology

Advances in research have transformed our understanding of breast cancers and have altered the daily practice of pathology. Theranostic evaluations performed by pathologists are now critical in triaging the patients into appropriate treatment groups, as are new guidelines that were recently established for the evaluation of HER2/neu gene amplification. Emerging molecular classifications of breast cancers bring novel perspectives to the assessment of individual cases, and opportunities for better treatments. Molecular studies have particularly shed light on distinct biological subsets of triple-negative breast cancers, for which new targeted therapies are being developed. The prognostic and therapeutic utility of new histopathologic parameters, such as tumor-infiltrating lymphocytes, are also being elucidated, and new protocols have been devised for the pathologic evaluation of breast specimens that have undergone neoadjuvant treatment. Novel clinical practices, such as radioactive seed localization, also affect the way breast specimens are processed and evaluated. In this brief review, we highlight the developments that are most relevant to pathology and are changing or could potentially impact our daily practice.

Oncolytic virotherapy including Rigvir and standard therapies in malignant melanoma

The treatment of metastatic melanoma has evolved from an era where interferon and chemotherapy were the mainstay of treatments to an era where immunotherapy has become the frontline. Ipilimumab (IgG1 CTLA-4 inhibitor), nivolumab (IgG4 PD-1 inhibitor), pembrolizumab (IgG4 PD-1 inhibitor) and nivolumab combined with ipilimumab have become first-line therapies in patients with metastatic melanoma. In addition, the high prevalence of BRAF mutations in melanoma has led to the discovery and approval of targeted molecules, such as vemurafenib (BRAF kinase inhibitor) and trametinib (MEK inhibitor), as they yielded improved responses and survival in malignant melanoma patients. This is certainly a burgeoning time in immunotherapy drug development, and the aforementioned efforts along with the recent US Food and Drug Administration approval of talimogene laherparepvec (T-VEC), a recombinant oncolytic herpes virus, have paved the way to exploring the role of additional oncolytic viruses, such as the echovirus Rigvir, as new and innovative treatment modalities in patients with melanoma. Herein, we discuss the current standard of care treatment in melanoma with an emphasis on immunotherapy and oncolytic viruses in development.

The cutting edge of metastatic melanoma therapy

The past decade has witnessed impressive new developments for the treatment of melanoma. The discovery of key oncogenic driver mutations, upon which tumor establishment and progression are dependent, changed the prognosis of patients with stage IV disease. Extensive preclinical and clinical studies have shown high response rates and survival benefits over conventional chemotherapies provided by target-specific inhibitors of BRAF- or NRAS-activating mutations. Recent genomic analyses of melanoma have also given new potentially targetable driver mutations. In addition, the quickened pace of development of immune checkpoint inhibitors for the treatment of melanoma offers the unique opportunity to provide a long-term clinical benefit. In this emerging era, predictive biomarkers for the selection of patients are required to help us develop an optimal therapeutic strategy.

Development of a Companion Diagnostic for Pembrolizumab in Non-Small Cell Lung Cancer Using Immunohistochemistry for Programmed Death Ligand-1

Context .- Programmed death ligand-1 (PD-L1) expression by tumors may enable them to avoid immunosurveillance. Objective .- To develop a PD-L1 immunohistochemical assay using the 22C3 anti-PD-L1 murine monoclonal antibody on the Dako platform as a possible companion diagnostic for pembrolizumab in patients with non-small cell lung cancer. Design .- Tumor samples from 146 patients with non-small cell lung cancer treated with pembrolizumab in KEYNOTE-001 and for whom response data were available were scored according to their staining intensity by a single pathologist using 4 methods: percentage of tumor cells staining at any intensity (PS1), moderate/strong intensity (PS2), strong intensity (PS3), and H-score (PS1 + PS2 + PS3). The cutoff score for predicting response to pembrolizumab was determined using receiver operating characteristic analysis. Progression-free and overall survival were assessed in patients with measurable disease per Response Evaluation Criteria in Solid Tumors, version 1.1 (n = 146). Results .- The 4 scoring methods assessed performed similarly; PS1 with a 50% cutoff score is the simplest and easiest method to implement in practice. Response to pembrolizumab was observed in 19 of 44 patients (43%) with a PS1 score of 50% or higher and 8 of 102 patients (8%) with PS1 lower than 50% (odds ratio, 8.93). Median progression-free and overall survival was 4.0 months and not yet reached, respectively, for patients with a PS1 of 50% or higher, and 2.1 and 6.1 months, respectively, for those with PS1 lower than 50%. Conclusion .- The PD-L1 immunohistochemical assay shows the potential for enrichment of trial populations and as a companion diagnostic tool in non-small cell lung cancer.

Rapid bone repair in a patient with lung cancer metastases to the spine using a novel herbal medicine: A case report

The prognosis of lung carcinoma with metastasis to the bone, particularly to the spine, is poor. Chemotherapy and radiotherapy are established treatments for metastatic bone disease, but their effectiveness is unsatisfactory and bone repair following their use is slow and difficult. Medicine prepared from herbal extracts may be an alternative treatment option. The present study discusses the case of a 59-year-old patient diagnosed with squamous cell lung cancer (T2N3M1) in which first-line chemotherapy using docetaxel plus cisplatin failed. Heavy multiple bone metastases were detected in the T9 vertebra and sixth left rib, resulting in a high risk of pathological fracture. Eastern Cooperative Oncology Group (ECOG) and numerical rating scale (NRS) scores of pain were 2 and 4, respectively. A second-line treatment was chosen consisting of biological intracontrol treatment (BICT) plus bisphosphonates administered over 40 days. BICT is a therapy involving the use of herbal extracts (including ginseng, herba agrimoniae, hairyvein agrimonia herb, white flower patrinia herb and arginine) and palliative care. A partial positive response was reached following use of this regimen, particularly with regard to bone repair. A computed tomography scan revealed a 90% reduction in the broken area of the rib cage and T9 vertebra. The bone repair was rapid and almost complete. In addition, growth of the primary tumor in the right pulmonary hilar and metastasis in the mediastinal lymph nodes were stabilized following treatment. ECOG and NRS scores were decreased to 1 and 0, respectively, leading to an improved quality of life. Based on these results, the present study suggests that this herbal medicine-based regimen promotes bone repair and inhibits tumor growth, with low toxicity. However, the mechanism by which herbal medicine promotes rapid bone repair is unclear. Further studies are required to determine whether cells in the tumor microenvironment are stimulated to undergo re-differentiation by unidentified herbal substances.

Exacerbation of myasthenia gravis in a patient with melanoma treated with pembrolizumab

INTRODUCTION

While anticancer immunotherapies have traditionally focused on activation of the immune system, there is recent interest in disinhibition of the natural antitumor immune response by targeting immune checkpoints such as cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) and programmed death-1 (PD-1). One humanized monoclonal antibody against PD-1, pembrolizumab, was recently approved for treatment of metastatic malignant melanoma.

METHODS

We report exacerbation of myasthenia gravis (MG) after treatment with pembrolizumab and provide a brief literature review.

RESULTS

We describe a 75-year-old man with stable MG who experienced myasthenic crisis in the setting of pembrolizumab treatment. A concurrent azathioprine taper was a possible although unlikely contributor given the short time interval between taper and exacerbation.

CONCLUSIONS

As long-term data become available regarding the adverse immune effects of novel checkpoint inhibitors, clinicians should be mindful of their risks/benefits and of possible autoimmune disease exacerbation. Muscle Nerve 54: 157-161, 2016.

Advanced gastric cancer: Current treatment landscape and future perspectives

Gastric cancer currently ranks fourth in cancer-related mortality worldwide. In the western world, it is most often diagnosed at an advanced stage, after becoming metastatic at distant sites. Patients with advanced disease (locally advanced or metastatic) have a somber prognosis, with a median overall survival of 10-12 mo, and palliative chemotherapy is the mainstay of treatment. In recent years, novel approaches using inhibition of human epidermal growth factor receptor 2 (HER2) have demonstrated significant improvements in progression-free and overall survival, compared with chemotherapy alone, in first-line treatment of patients with overexpression of HER2. In addition, both second-line chemotherapy and treatment with the vascular endothelial growth factor receptor-inhibitor ramucirumab demonstrated significant benefits in terms of overall survival, compared with best supportive care, in randomized studies. Moreover, ramucirumab in combination with chemotherapy demonstrated further significant benefits in terms of progression-free and overall survival, compared with chemotherapy alone, in second-line treatment for patients with metastatic gastric cancer. A recently published molecular classification of gastric cancer is expected to improve patient stratification and selection for clinical trials and provide a roadmap for future drug development. Nevertheless, despite these developments the prognosis of patients with advanced gastric cancer remains poor. In this review we discuss current standards of care and outline major topics of drug development in gastric cancer.

Tumour progression and metastasis

The two biological mechanisms that determine types of malignancy are infiltration and metastasis, for which tumour microenvironment plays a key role in developing and establishing the morphology, growth and invasiveness of a malignancy. The microenvironment is formed by complex tissue containing the extracellular matrix, tumour and non-tumour cells, a signalling network of cytokines, chemokines, growth factors, and proteases that control autocrine and paracrine communication among individual cells, facilitating tumour progression. During the development of the primary tumour, the tumour stroma and continuous genetic changes within the cells makes it possible for them to migrate, having to count on a pre-metastatic niche receptor that allows the tumour’s survival and distant growth. These niches are induced by factors produced by the primary tumour; if it is eradicated, the active niches become responsible for activating the latent disseminated cells. Due to the importance of these mechanisms, the strategies that develop tumour cells during tumour progression and the way in which the microenvironment influences the formation of metastasis are reviewed. It also suggests that the metastatic niche can be an ideal target for new treatments that make controlling metastasis possible.

Molecular Profiling of Refractory Adrenocortical Cancers and Predictive Biomarkers to Therapy

PURPOSE

Current first-line chemotherapy for patients with metastatic adrenocortical cancer (ACC) includes doxorubicin, etoposide, cisplatin, and mitotane with a reported response rate of only 23.2%. New therapeutic leads for patients with refractory tumors are needed; there is no standard second-line treatment.

METHODS

Samples from 135 ACC tumors were analyzed by immunohistochemistry, in situ hybridization (FISH or CISH), and/or gene sequencing at a single commercial reference laboratory (Caris Life Sciences) to identify markers associated with drug sensitivity and resistance.

RESULTS

Overexpression of proteins related to demonstrated chemotherapy sensitivity or resistance included topoisomerase 1, progesterone receptor, and topoisomerase 2-alpha in 46%, 63%, and 42% of cases, respectively. Loss of excision repair cross-complementary group 1 (ERCC1), phosophatase and tensin homolog, O(6)-methylguanine-methyltransferase, and ribonucleotide reductase M1 (RRM1) was identified in 56%, 59%, 71%, and 58% of cases, respectively. Other aberrations included overexpression of programmed death-ligand 1 or programmed cell death protein 1 tumor-infiltrating lymphocytes in >40% of cases. In all, 35% of cases had a mutation in the canonical Wnt signaling pathway (either CTNNB1 or APC) and 48% had a mutation in TP53. No other genomic alterations were identified.

CONCLUSION

Biomarker alterations in ACC may be used to direct therapies, including recommendations for and potential resistance of some patients to traditional chemotherapies, which may explain the low response rate in the unselected population. Limited outcomes data support the use of mitotane and platinum therapies for patients with low levels of the proteins RRM1 and ERCC1.

Multistep, effective drug distribution within solid tumors

The distribution of drugs within solid tumors presents a long-standing barrier for efficient cancer therapies. Tumors are highly resistant to diffusion, and the lack of blood and lymphatic flows suppresses convection. Prolonged, continuous intratumoral drug delivery from a miniature drug source offers an alternative to both systemic delivery and intratumoral injection. Presented here is a model of drug distribution from such a source, in a multistep process. At delivery onset the drug mainly affects the closest surroundings. Such 'priming' enables drug penetration to successive cell layers. Tumor 'void volume' (volume not occupied by cells) increases, facilitating lymphatic perfusion. The drug is then transported by hydraulic convection downstream along interstitial fluid pressure (IFP) gradients, away from the tumor core. After a week tumor cell death occurs throughout the entire tumor and IFP gradients are flattened. Then, the drug is transported mainly by 'mixing', powered by physiological bulk body movements. Steady state is achieved and the drug covers the entire tumor over several months. Supporting measurements are provided from the LODER system, releasing siRNA against mutated KRAS over months in pancreatic cancer in-vivo models. LODER was also successfully employed in a recent Phase 1/2 clinical trial with pancreatic cancer patients.

Bladder cancer in the elderly patient: challenges and solutions

Bladder cancer (BC) is an age-associated malignancy with increased prevalence in the elderly population. Elderly patients are a vulnerable population at increased risk for treatment-related toxicity secondary to medical comorbidities and geriatric syndromes. As a result, this population has been historically undertreated and suffers worse disease-specific outcomes than younger patients with BC. Recognition of this disparity has led to efforts to individualize treatment decisions based on functional status rather than chronologic age in an effort to optimize the use of curative therapies for the fit elderly and modify treatments to reduce the risk of toxicity and disease-related morbidity in vulnerable or frail patients. The comprehensive geriatric assessment is a decision framework that helps to balance underlying health considerations and risks of therapy with aggressiveness of the cancer. Development of systemic therapies with increased efficacy against BC and reduced toxicity are eagerly awaited, as are techniques and interventions to reduce the morbidity from surgery and radiation for patients with BC.