Spectrum of Mechanisms of Resistance to Crizotinib and Lorlatinib in ROS1 Fusion-Positive Lung Cancer.

PURPOSE: Current standard initial therapy for advanced, ROS proto-oncogene 1, receptor tyrosine kinase fusion (ROS1)-positive (ROS1+) non-small cell lung cancer (NSCLC) is crizotinib or entrectinib. Lorlatinib, a next-generation anaplastic lymphoma kinase/ROS1 inhibitor, recently demonstrated efficacy in ROS1+ NSCLC, including in crizotinib-pretreated patients. However, mechanisms of lorlatinib resistance in ROS1+ disease remain poorly understood. Here, we assessed mechanisms of resistance to crizotinib and lorlatinib. EXPERIMENTAL DESIGN: Biopsies from patients with ROS1 + NSCLC progressing on crizotinib or lorlatinib were profiled by genetic sequencing. RESULTS: From 55 patients, 47 post-crizotinib and 32 post-lorlatinib biopsies were assessed. Among 42 post-crizotinib and 28 post-lorlatinib biopsies analyzed at distinct timepoints, ROS1 mutations were identified in 38% and 46%, respectively. ROS1 G2032R was the most commonly occurring mutation in approximately one third of cases. Additional ROS1 mutations included D2033N (2.4%) and S1986F (2.4%) post-crizotinib and L2086F (3.6%), G2032R/L2086F (3.6%), G2032R/S1986F/L2086F (3.6%), and S1986F/L2000V (3.6%) post-lorlatinib. Structural modeling predicted ROS1L2086F causes steric interference to lorlatinib, crizotinib, and entrectinib, while it may accommodate cabozantinib. In Ba/F3 models, ROS1L2086F, ROS1G2032R/L2086F, and ROS1S1986F/G2032R/L2086F were refractory to lorlatinib but sensitive to cabozantinib. A patient with disease progression on crizotinib and lorlatinib and ROS1 L2086F received cabozantinib for nearly 11 months with disease control. Among lorlatinib-resistant biopsies, we also identified MET amplification (4%), KRAS G12C (4%), KRAS amplification (4%), NRAS mutation (4%), and MAP2K1 mutation (4%). CONCLUSIONS: ROS1 mutations mediate resistance to crizotinib and lorlatinib in more than one third of cases, underscoring the importance of developing next-generation ROS1 inhibitors with potency against these mutations, including G2032R and L2086F. Continued efforts are needed to elucidate ROS1-independent resistance mechanisms.

Psychosocial needs of young breast cancer survivors in Mexico City, Mexico.

OBJECTIVE: Young breast cancer survivors in Mexico face distinct psychosocial challenges that have not been characterized. This study aims to describe the psychosocial needs of young breast cancer survivors in Mexico at 5 or more years of survivorship, identifying areas of focus for early interventions. METHODS: Breast cancer patients diagnosed at age 40 or prior with 5 or more years since diagnosis were invited to participate in one-on-one 30-60 minute semi-structured audio-recorded interviews at the Instituto Nacional de Cancerología in Mexico City. Transcripts were coded using thematic analysis with NVivo software. RESULTS: 25 women participated. Five major phenomena emerged from analysis: (1) minimization of fertility concerns; (2) persistence of body image disturbance over time; (3) barriers to employment during survivorship; (4) impact on family relationships and social networks; & (5) unmet psychological care and informational needs. CONCLUSIONS: Early interventions with a focus on fertility loss education, access to reconstructive surgery and body image support, guidance during return-to-work, assistance with childcare, integration of psychological care and the fulfillment of informational needs could ameliorate long-term psychological and social distress for young breast cancer survivors in Mexico.

Safety of Combined PD-1 Pathway Inhibition and Intracranial Radiation Therapy in Non-Small Cell Lung Cancer.

INTRODUCTION: Intracranial metastases are a common cause of morbidity and mortality in patients with advanced NSCLC, and are frequently managed with radiation therapy (RT). The safety of cranial RT in the setting of treatment with immune checkpoint inhibitors (ICIs) has not been established. METHODS: We identified patients with advanced NSCLC with brain metastases who received cranial RT and were treated with or without programmed cell death 1/programmed death ligand 1 inhibitors between August 2013 and September 2016. RT-related adverse events (AEs) were retrospectively evaluated and analyzed according to ICI treatment status, cranial RT type, and timing of RT with respect to ICI. RESULTS: Of 163 patients, 50 (31%) received ICIs, whereas 113 (69%) were ICI naive. Overall, 94 (58%), 28 (17%), and 101 (62%) patients received stereotactic radiosurgery, partial brain irradiation, and/or whole brain RT, respectively. Fifty percent of patients received more than one radiation course. We observed no significant difference in rates of all-grade AEs and grade 3 or higher AEs between the ICI-naive and ICI-treated patients across different cranial RT types (grade ≥3 AEs in 8% of ICI-naive patients versus in 9% of ICI-treated patients for stereotactic radiosurgery [p = 1.00] and in 8% of ICI-naive patients versus in 10% of ICI-treated patients for whole brain RT [p = 0.71]). Additionally, there was no difference in AE rates on the basis of timing of ICI administration with respect to RT. CONCLUSIONS: Treatment with an ICI and cranial RT was not associated with a significant increase in RT-related AEs, suggesting that use of programmed cell death 1/programmed death ligand 1 inhibitors in patients receiving cranial RT may have an acceptable safety profile. Nonetheless, additional studies are needed to validate this approach.

Patterns of Metastatic Spread and Mechanisms of Resistance to Crizotinib in ROS1-Positive Non-Small-Cell Lung Cancer.

PURPOSE: The ROS1 tyrosine kinase is activated through ROS1 gene rearrangements in 1-2% of non-small cell lung cancer (NSCLC), conferring sensitivity to treatment with the ALK/ROS1/MET inhibitor crizotinib. Currently, insights into patterns of metastatic spread and mechanisms of crizotinib resistance among ROS1-positive patients are limited. PATIENTS AND METHODS: We reviewed clinical and radiographic imaging data of patients with ROS1- and ALK-positive NSCLC in order to compare patterns of metastatic spread at initial metastatic diagnosis. To determine molecular mechanisms of crizotinib resistance, we also analyzed repeat biopsies from a cohort of ROS1-positive patients progressing on crizotinib. RESULTS: We identified 39 and 196 patients with advanced ROS1- and ALK-positive NSCLC, respectively. ROS1-positive patients had significantly lower rates of extrathoracic metastases (ROS1 59.0%, ALK 83.2%, P=0.002), including lower rates of brain metastases (ROS1 19.4%, ALK 39.1%; P = 0.033), at initial metastatic diagnosis. Despite similar overall survival between ALK- and ROS1-positive patients treated with crizotinib (median 3.0 versus 2.5 years, respectively; P=0.786), ROS1-positive patients also had a significantly lower cumulative incidence of brain metastases (34% vs. 73% at 5 years; P<0.0001). Additionally, we identified 16 patients who underwent a total of 17 repeat biopsies following progression on crizotinib. ROS1 resistance mutations were identified in 53% of specimens, including 9/14 (64%) non-brain metastasis specimens. ROS1 mutations included: G2032R (41%), D2033N (6%), and S1986F (6%). CONCLUSIONS: Compared to ALK rearrangements, ROS1 rearrangements are associated with lower rates of extrathoracic metastases, including fewer brain metastases, at initial metastatic diagnosis. ROS1 resistance mutations, particularly G2032R, appear to be the predominant mechanism of resistance to crizotinib, underscoring the need to develop novel ROS1 inhibitors with activity against these resistant mutants.

Regulatory T cells occupy an isolated niche in the intestine that is antigen independent.

Regulatory T cells (Tregs) are CD4(+) T cells that maintain immune homeostasis and prevent autoimmunity. Like all CD4(+) T cells, Tregs require antigen-specific signals via T cell receptor-major histocompatibility complex class II (TCR-MHCII) interactions for their development. However, the requirement for MHCII in Treg homeostasis in tissues such as intestinal lamina propria (LP) is unknown. We examined LP Treg homeostasis in a transgenic mouse model that lacks peripheral TCR-MHCII interactions and generation of extrathymic Tregs (iTregs). Thymically generated Tregs entered the LP of weanlings and proliferated independently of MHCII to fill the compartment. The adult LP was a closed niche; new thymic Tregs were excluded, and Tregs in parabiotic pairs were LP resident. The isolated LP niche was interleukin-2 (IL-2) independent but dependent on commensal bacteria. Thus, an LP Treg niche can be filled, isolated, and maintained independently of antigen signals and iTregs. This niche may represent a tissue-specific mechanism for maintaining immune tolerance.

NR4A1 (Nur77) deletion polarizes macrophages toward an inflammatory phenotype and increases atherosclerosis.

RATIONALE: NR4A1 (Nur77) is a nuclear receptor that is expressed in macrophages and within atherosclerotic lesions, yet its function in atherosclerosis is unknown. OBJECTIVE: Nur77 regulates the development of monocytes, particularly patrolling Ly6C(-) monocytes that may be involved in resolution of inflammation. We sought to determine how absence of nuclear receptor subfamily 4, group A, member 1 (NR4A1) in hematopoietic cells affected atherosclerosis development. METHODS AND RESULTS: Nur77(-/-) chimeric mice on a Ldlr(-/-) background showed a 3-fold increase in atherosclerosis development when fed a Western diet for 20 weeks, despite having a drastic reduction in Ly6C(-) patrolling monocytes. In a second model, mice deficient in both Nur77 and ApoE (ApoE(-/-)Nur77(-/-)) also showed increased atherosclerosis after 11 weeks of Western diet. Atherosclerosis was associated with a significant change in macrophage polarization toward a proinflammatory phenotype, with high expression of tumor necrosis factor-α and nitric oxide and low expression of Arginase-I. Moreover, we found increased expression of toll-like receptor 4 mRNA and protein in Nur77(-/-) macrophages as well as increased phosphorylation of the p65 subunit of NFκB. Inhibition of NFκB activity blocked excess activation of Nur77(-/-) macrophages. CONCLUSIONS: We conclude that the absence of Nur77 in monocytes and macrophages results in enhanced toll-like receptor signaling and polarization of macrophages toward a proinflammatory M1 phenotype. Despite having fewer monocytes, Nur77(-/-) mice developed significant atherosclerosis when fed a Western diet. These studies indicate that Nur77 is a novel target for modulating the inflammatory phenotype of monocytes and macrophages and may be important for regulation of atherogenesis.

Myelofibrosis 2012: it's complicated.

Major advances in myeloproliferative neoplasms in the last decade have cast light on their complexity. The identification of JAK2 (V617F) briefly promised a unifying mechanism of pathogenesis with a single pathway that could be efficiently targeted. Instead, there have been major advances in understanding acquired and background genetic and epigenetic contributors to this group of disorders, with refined risk prediction models and experimental therapeutics that have provided a more nuanced model of disease. In aggregate these observations likely explain the heterogeneity of these disorders and their generally unpredictable response to therapy. Molecular studies, beginning with the identification of JAK2 (V617F), have led to a concept of MPN subtypes existing on a continuum, and additional discoveries such as TET2 and EZH2 mutations have provided the molecular underpinnings to begin to explain overlapping phenotypes in myeloid malignancies more generally. In many ways the pace of molecular discovery is outstripping our ability to integrate these observations into clinical care, both in terms of molecular diagnostics and medical decision making. This review will attempt to summarize, within a clinical context, our evolving understanding of myeloproliferative neoplasms. It focuses on biology, histopathology, prognostic scoring systems, stem cell transplantation as well as selected clinical/preclinical therapeutic observations.

The transcription factor NR4A1 (Nur77) controls bone marrow differentiation and the survival of Ly6C- monocytes.

The transcription factors that regulate differentiation into the monocyte subset in bone marrow have not yet been identified. Here we found that the orphan nuclear receptor NR4A1 controlled the differentiation of Ly6C- monocytes. Ly6C- monocytes, which function in a surveillance role in circulation, were absent from Nr4a1-/- mice. Normal numbers of myeloid progenitor cells were present in Nr4a1-/- mice, which indicated that the defect occurred during later stages of monocyte development. The defect was cell intrinsic, as wild-type mice that received bone marrow from Nr4a1-/- mice developed fewer patrolling monocytes than did recipients of wild-type bone marrow. The Ly6C- monocytes remaining in the bone marrow of Nr4a1-/- mice were arrested in S phase of the cell cycle and underwent apoptosis. Thus, NR4A1 functions as a master regulator of the differentiation and survival of 'patrolling' Ly6C- monocytes.