James Ziai

Atezolizumab in combination with bevacizumab enhances antigen-specific T-cell migration in metastatic renal cell carcinoma

Anti-tumour immune activation by checkpoint inhibitors leads to durable responses in a variety of cancers, but combination approaches are required to extend this benefit beyond a subset of patients. In preclinical models tumour-derived VEGF limits immune cell activity while anti-VEGF augments intra-tumoral T-cell infiltration, potentially through vascular normalization and endothelial cell activation. This study investigates how VEGF blockade with bevacizumab could potentiate PD-L1 checkpoint inhibition with atezolizumab in mRCC. Tissue collections are before treatment, after bevacizumab and after the addition of atezolizumab. We discover that intra-tumoral CD8+ T cells increase following combination treatment. A related increase is found in intra-tumoral MHC-I, Th1 and T-effector markers, and chemokines, most notably CX3CL1 (fractalkine). We also discover that the fractalkine receptor increases on peripheral CD8+ T cells with treatment. Furthermore, trafficking lymphocyte increases are observed in tumors following bevacizumab and combination treatment. These data suggest that the anti-VEGF and anti-PD-L1 combination improves antigen-specific T-cell migration.

TGFβ attenuates tumour response to PD-L1 blockade by contributing to exclusion of T cells

Therapeutic antibodies that block the programmed death-1 (PD-1)–programmed death-ligand 1 (PD-L1) pathway can induce robust and durable responses in patients with various cancers, including metastatic urothelial cancer. However, these responses only occur in a subset of patients. Elucidating the determinants of response and resistance is key to improving outcomes and developing new treatment strategies. Here we examined tumours from a large cohort of patients with metastatic urothelial cancer who were treated with an anti-PD-L1 agent (atezolizumab) and identified major determinants of clinical outcome. Response to treatment was associated with CD8+ T-effector cell phenotype and, to an even greater extent, high neoantigen or tumour mutation burden. Lack of response was associated with a signature of transforming growth factor β (TGFβ) signalling in fibroblasts. This occurred particularly in patients with tumours, which showed exclusion of CD8+ T cells from the tumour parenchyma that were instead found in the fibroblast- and collagen-rich peritumoural stroma; a common phenotype among patients with metastatic urothelial cancer. Using a mouse model that recapitulates this immune-excluded phenotype, we found that therapeutic co-administration of TGFβ-blocking and anti-PD-L1 antibodies reduced TGFβ signalling in stromal cells, facilitated T-cell penetration into the centre of tumours, and provoked vigorous anti-tumour immunity and tumour regression. Integration of these three independent biological features provides the best basis for understanding patient outcome in this setting and suggests that TGFβ shapes the tumour microenvironment to restrain anti-tumour immunity by restricting T-cell infiltration.

Sustained Brown Fat Stimulation and Insulin Sensitization by a Humanized Bispecific Antibody Agonist for Fibroblast Growth Factor Receptor 1/βKlotho Complex

Dissipating excess calories as heat through therapeutic stimulation of brown adipose tissues (BAT) has been proposed as a potential treatment for obesity-linked disorders. Here, we describe the generation of a humanized effector-less bispecific antibody that activates fibroblast growth factor receptor (FGFR) 1/βKlotho complex, a common receptor for FGF21 and FGF19. Using this molecule, we show that antibody-mediated activation of FGFR1/βKlotho complex in mice induces sustained energy expenditure in BAT, browning of white adipose tissue, weight loss, and improvements in obesity-associated metabolic derangements including insulin resistance, hyperglycemia, dyslipidemia and hepatosteatosis. In mice and cynomolgus monkeys, FGFR1/βKlotho activation increased serum high-molecular-weight adiponectin, which appears to contribute over time by enhancing the amplitude of the metabolic benefits. At the same time, insulin sensitization by FGFR1/βKlotho activation occurs even before the onset of weight loss in a manner that is independent of adiponectin. Together, selective activation of FGFR1/βKlotho complex with a long acting therapeutic antibody represents an attractive approach for the treatment of type 2 diabetes and other obesity-linked disorders through enhanced energy expenditure, insulin sensitization and induction of high-molecular-weight adiponectin.

BRAF mutation testing in clinical practice.

Activating mutation of KRAS plays a significant role in the pathogenesis of common human malignancies and molecular testing of KRAS mutation has emerged as an essential biomarker in the current practice of clinical oncology. The presence of KRAS mutation is generally associated with clinical aggressiveness of the cancer and reduced survival of the patient. Therapeutically, KRAS mutation testing has maximum utility in stratifying metastatic colorectal carcinoma and lung cancer patients for treatment with targeted therapy. Diagnostically, KRAS mutation testing is useful in the workup of pancreaticobiliary and thyroid cancers, particularly using cytological specimens. In the era of precision medicine, the role of KRAS mutation testing is poised to expand, likely in a setting of combinatorial therapeutic strategy and requiring additional mutation testing of its upstream and/or downstream effectors.

BRAFmutation testing in clinical practice

Serine/threonine-protein kinase BRAF, a downstream effector of the RAS oncogene along the MEK/ERK signaling pathway, has emerged as an important biological marker for diagnosis, prognosis and therapeutic guidance for human cancers. The high prevalence of BRAFV600E activating mutation in papillary thyroid carcinoma, cutaneous malignant melanoma and hairy cell leukemia implies that the mutation is an important ’driver‘ or ’codriver‘ in the development of a subset of these cancers. Diagnostically, the BRAFV600E mutation is a powerful molecular marker for papillary thyroid carcinoma and, quite possibly, hairy cell leukemia as well. Cancers with a BRAF mutation are generally more aggressive than their counterparts without the mutation. Importantly, mutant BRAF has been a highly attractive target for precision cancer therapy. Indeed, recent studies in the clinical trials of BRAF inhibitors in patients with malignant melanoma are changing the treatment paradigm of this highly lethal disease. BRAF mutation testing using highly sensitive and specific methodology in a molecular diagnostic laboratory is essential in the current clinical practice of oncology.

Pathology Resident and Fellow Education in a Time of Disruptive Technologies

The development of disruptive technologies is changing the practice of pathology. Their implementation challenges traditional educational paradigms. Training programs must adapt to these heuristic needs. The dual explosion of new medical knowledge and innovative methodologies adds new practice aspects to the pathologists areas of expertise. This transformation potentially challenges the traditional core model of training. It raises questions as to how pathology should incorporate future expanding subspecialty needs into educational and practice models. This article examines the impact of these disruptive technologies on resident and fellow education and explores alternative educational and practice models that may better accommodate pathologys future.

Mismatch repair deficiency testing in clinical practice

ABSTRACT Lynch syndrome, an autosomal dominant inherited disorder, is caused by inactivating mutations involving DNA mismatch repair (MMR) genes. This leads to profound genetic instability, including microsatellite instability (MSI) and increased risk for cancer development, particularly colon and endometrial malignancies. Clinical testing of tumor tissues for the presence of MMR gene deficiency is standard practice in clinical oncology, with immunohistochemistry and PCR-based microsatellite instability analysis used as screening tests to identify potential Lynch syndrome families. The ultimate diagnosis of Lynch syndrome requires documentation of mutation within one of the four MMR genes (MLH1, PMS2, MSH2 and MSH6) or EPCAM, currently achieved by comprehensive sequencing analysis of germline DNA. In this review, the genetic basis of Lynch syndrome, methodologies of MMR deficiency testing, and current diagnostic algorithms in the clinical management of Lynch syndrome, are discussed.

Pulmonary squamous cell carcinoma associated with repaired congenital tracheoesophageal fistula and esophageal atresia.

We report a 19‐year‐old man with pulmonary squamous cell carcinoma (SCC) who had a history of vertebral, anal, cardiac, tracheal, esophageal, renal, and radial limb defects (VACTERL) association and tracheoesophageal fistula (TEF) + esophageal atresia (EA) repair as an infant. Children that undergo TEF + EA repair may have an increased risk for developing cancer as they reach adulthood. Pediatr Pulmonol. 2010; 45:202–204.

Chronic Neutrophilic Leukemia: A Rare and Difficult Diagnosis of Exclusion

Chronic neutrophilic leukemia (CNL) is an extremely rare myeloproliferative disorder that presents diagnostic challenges for both pathologists and treating clinicians. Because this disease entity is very rare, and because it is typically a diagnosis of exclusion, it is important for pathologists and hematologists to be familiar with CNL when approaching the patient with a myeloproliferative clinical picture. Thus, the objectives of this report are: 1) to detail the clinical case of a 59 year old male veteran with initial presentation of hyperleukocytosis, 2) to review the differential diagnosis of a granulocytic myeloproliferative presentation and demonstrate the laboratory and clinical criteria utilized to establish a diagnosis of CNL in this case, and 3) to briefly review the current literature on the diagnosis and treatment of CNL.

FGF21 mimetic antibody stimulates UCP1-independent brown fat thermogenesis via FGFR1/βKlotho complex in non-adipocytes

Objective Fibroblast Growth Factor 21 (FGF21) is a potent stimulator of brown fat thermogenesis that improves insulin sensitivity, ameliorates hepatosteatosis, and induces weight loss by engaging the receptor complex comprised of Fibroblast Growth Factor Receptor 1 (FGFR1) and the requisite coreceptor βKlotho. Previously, recombinant antibody proteins that activate the FGFR1/βKlotho complex were proposed to act as an FGF21-mimetic; however, in vivo action of these engineered proteins has not been well studied. Methods We investigated the mechanism by which anti-FGFR1/βKlotho bispecific antibody (bFKB1) stimulates thermogenesis in UCP1-expressing brown adipocytes using genetically engineered mice. Anti-FGFR1 agonist antibody was also used to achieve brown adipose tissue restricted activation in transgenic mice. Results Studies with global Ucp1-deficient mice and adipose-specific Fgfr1 deficient mice demonstrated that bFKB1 acts on targets distal to adipocytes and indirectly stimulates brown adipose thermogenesis in a UCP1-independent manner. Using a newly developed transgenic system, we also show that brown adipose tissue restricted activation of a transgenic FGFR1 expressed under the control of Ucp1 promoter does not stimulate energy expenditure. Finally, consistent with its action as a FGF21 mimetic, bFBK1 suppresses intake of saccharin-containing food and alcohol containing water in mice. Conclusions Collectively, we propose that FGFR1/βKlotho targeted therapy indeed mimics the action of FGF21 in vivo and stimulates UCP1-independent brown fat thermogenesis through receptors outside of adipocytes and likely in the nervous system.