Zofia Piotrowska

Rociletinib in EGFR-mutated non-small-cell lung cancer.

BACKGROUND Non-small-cell lung cancer (NSCLC) with a mutation in the gene encoding epidermal growth factor receptor (EGFR) is sensitive to approved EGFR inhibitors, but resistance develops, mediated by the T790M EGFR mutation in most cases. Rociletinib (CO-1686) is an EGFR inhibitor active in preclinical models of EGFR-mutated NSCLC with or without T790M. METHODS In this phase 1-2 study, we administered rociletinib to patients with EGFR-mutated NSCLC who had disease progression during previous treatment with an existing EGFR inhibitor. In the expansion (phase 2) part of the study, patients with T790M-positive disease received rociletinib at a dose of 500 mg twice daily, 625 mg twice daily, or 750 mg twice daily. Key objectives were assessment of safety, side-effect profile, pharmacokinetics, and preliminary antitumor activity of rociletinib. Tumor biopsies to identify T790M were performed during screening. Treatment was administered in continuous 21-day cycles. RESULTS A total of 130 patients were enrolled. The first 57 patients to be enrolled received the free-base form of rociletinib (150 mg once daily to 900 mg twice daily). The remaining patients received the hydrogen bromide salt (HBr) form (500 mg twice daily to 1000 mg twice daily). A maximum tolerated dose (the highest dose associated with a rate of dose-limiting toxic effects of less than 33%) was not identified. The only common dose-limiting adverse event was hyperglycemia. In an efficacy analysis that included patients who received free-base rociletinib at a dose of 900 mg twice daily or the HBr form at any dose, the objective response rate among the 46 patients with T790M-positive disease who could be evaluated was 59% (95% confidence interval [CI], 45 to 73), and the rate among the 17 patients with T790M-negative disease who could be evaluated was 29% (95% CI, 8 to 51). CONCLUSIONS Rociletinib was active in patients with EGFR-mutated NSCLC associated with the T790M resistance mutation. (Funded by Clovis Oncology; ClinicalTrials.gov number, NCT01526928.).

Tumor cells can follow distinct evolutionary paths to become resistant to epidermal growth factor receptor inhibition

Although mechanisms of acquired resistance of epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancers to EGFR inhibitors have been identified, little is known about how resistant clones evolve during drug therapy. Here we observe that acquired resistance caused by the EGFRT790M gatekeeper mutation can occur either by selection of pre-existing EGFRT790M-positive clones or via genetic evolution of initially EGFRT790M-negative drug-tolerant cells. The path to resistance impacts the biology of the resistant clone, as those that evolved from drug-tolerant cells had a diminished apoptotic response to third-generation EGFR inhibitors that target EGFRT790M; treatment with navitoclax, an inhibitor of the anti-apoptotic factors BCL-xL and BCL-2 restored sensitivity. We corroborated these findings using cultures derived directly from EGFR inhibitor–resistant patient tumors. These findings provide evidence that clinically relevant drug-resistant cancer cells can both pre-exist and evolve from drug-tolerant cells, and they point to therapeutic opportunities to prevent or overcome resistance in the clinic.

Heterogeneity Underlies the Emergence of EGFRT790 Wild-Type Clones Following Treatment of T790M-Positive Cancers with a Third-Generation EGFR Inhibitor

UNLABELLED Rociletinib is a third-generation EGFR inhibitor active in lung cancers with T790M, the gatekeeper mutation underlying most first-generation EGFR drug resistance. We biopsied patients at rociletinib progression to explore resistance mechanisms. Among 12 patients with T790M-positive cancers at rociletinib initiation, six had T790-wild-type rociletinib-resistant biopsies. Two T790-wild-type cancers underwent small cell lung cancer transformation; three T790M-positive cancers acquired EGFR amplification. We documented T790-wild-type and T790M-positive clones coexisting within a single pre-rociletinib biopsy. The pretreatment fraction of T790M-positive cells affected response to rociletinib. Longitudinal circulating tumor DNA (ctDNA) analysis revealed an increase in plasma EGFR-activating mutation, and T790M heralded rociletinib resistance in some patients, whereas in others the activating mutation increased but T790M remained suppressed. Together, these findings demonstrate the role of tumor heterogeneity when therapies targeting a singular resistance mechanism are used. To further improve outcomes, combination regimens that also target T790-wild-type clones are required. SIGNIFICANCE This report documents that half of T790M-positive EGFR-mutant lung cancers treated with rociletinib are T790-wild-type upon progression, suggesting that T790-wild-type clones can emerge as the dominant source of resistance. We show that tumor heterogeneity has important clinical implications and that plasma ctDNA analyses can sometimes predict emerging resistance mechanisms.

EGFR Mutations and ALK Rearrangements Are Associated with Low Response Rates to PD-1 Pathway Blockade in Non–Small Cell Lung Cancer: A Retrospective Analysis

Purpose: PD-1 inhibitors are established agents in the management of non–small cell lung cancer (NSCLC); however, only a subset of patients derives clinical benefit. To determine the activity of PD-1/PD-L1 inhibitors within clinically relevant molecular subgroups, we retrospectively evaluated response patterns among EGFR-mutant, anaplastic lymphoma kinase (ALK)-positive, and EGFR wild-type/ALK-negative patients. Experimental Design: We identified 58 patients treated with PD-1/PD-L1 inhibitors. Objective response rates (ORR) were assessed using RECIST v1.1. PD-L1 expression and CD8+ tumor-infiltrating lymphocytes (TIL) were evaluated by IHC. Results: Objective responses were observed in 1 of 28 (3.6%) EGFR-mutant or ALK-positive patients versus 7 of 30 (23.3%) EGFR wild-type and ALK-negative/unknown patients (P = 0.053). The ORR among never- or light- (≤10 pack years) smokers was 4.2% versus 20.6% among heavy smokers (P = 0.123). In an independent cohort of advanced EGFR-mutant (N = 68) and ALK-positive (N = 27) patients, PD-L1 expression was observed in 24%/16%/11% and 63%/47%/26% of pre–tyrosine kinase inhibitor (TKI) biopsies using cutoffs of ≥1%, ≥5%, and ≥50% tumor cell staining, respectively. Among EGFR-mutant patients with paired, pre- and post-TKI–resistant biopsies (N = 57), PD-L1 expression levels changed after resistance in 16 (28%) patients. Concurrent PD-L1 expression (≥5%) and high levels of CD8+ TILs (grade ≥2) were observed in only 1 pretreatment (2.1%) and 5 resistant (11.6%) EGFR-mutant specimens and was not observed in any ALK-positive, pre- or post-TKI specimens. Conclusions: NSCLCs harboring EGFR mutations or ALK rearrangements are associated with low ORRs to PD-1/PD-L1 inhibitors. Low rates of concurrent PD-L1 expression and CD8+ TILs within the tumor microenvironment may underlie these clinical observations. Clin Cancer Res; 22(18); 4585–93. ©2016 AACR. See related commentary by Gettinger and Politi, p. 4539

Circulating tumour DNA profiling reveals heterogeneity of EGFR inhibitor resistance mechanisms in lung cancer patients

Circulating tumour DNA (ctDNA) analysis facilitates studies of tumour heterogeneity. Here we employ CAPP-Seq ctDNA analysis to study resistance mechanisms in 43 non-small cell lung cancer (NSCLC) patients treated with the third-generation epidermal growth factor receptor (EGFR) inhibitor rociletinib. We observe multiple resistance mechanisms in 46% of patients after treatment with first-line inhibitors, indicating frequent intra-patient heterogeneity. Rociletinib resistance recurrently involves MET, EGFR, PIK3CA, ERRB2, KRAS and RB1. We describe a novel EGFR L798I mutation and find that EGFR C797S, which arises in ∼33% of patients after osimertinib treatment, occurs in <3% after rociletinib. Increased MET copy number is the most frequent rociletinib resistance mechanism in this cohort and patients with multiple pre-existing mechanisms (T790M and MET) experience inferior responses. Similarly, rociletinib-resistant xenografts develop MET amplification that can be overcome with the MET inhibitor crizotinib. These results underscore the importance of tumour heterogeneity in NSCLC and the utility of ctDNA-based resistance mechanism assessment.

The allelic context of the C797S mutation acquired upon treatment with third generation EGFR inhibitors impacts sensitivity to subsequent treatment strategies

Purpose: A secondary EGFR mutation, T790M, is the most common resistance mechanism in EGFR-mutant adenocarcinomas that have progressed on erlotinib. Third-generation EGFR inhibitors capable of inhibiting mutant EGFR with T790M produce responses in nearly two thirds of patients. However, acquired resistance mechanisms in patients treated with these drugs are yet to be described. Experimental Design: To study acquired resistance to third-generation EGFR inhibitors, T790M-positive cells derived from an erlotinib-resistant cancer were made resistant to a third-generation TKI and then characterized using cell and molecular analyses. Results: Cells resistant to a third-generation TKI acquired an additional EGFR mutation, C797S, which prevented suppression of EGFR. Our results demonstrate that the allelic context in which C797S was acquired may predict responsiveness to alternative treatments. If the C797S and T790M mutations are in trans, cells will be resistant to third-generation EGFR TKIs, but will be sensitive to a combination of first- and third-generation TKIs. If the mutations are in cis, no EGFR TKIs alone or in combination can suppress activity. If C797S develops in cells wild-type for T790 (when third-generation TKIs are administered in the first-line setting), the cells are resistant to third-generation TKIs, but retain sensitivity to first-generation TKIs. Conclusions: Mutation of C797S in EGFR is a novel mechanism of acquired resistance to third-generation TKIs. The context in which the C797S develops with respect to the other EGFR alleles affects the efficacy of subsequent treatments. Clin Cancer Res; 21(17); 3924–33. ©2015 AACR. See related commentary by Ayeni et al., p. 3818

Microsatellite instability and expression of MLH1 and MSH2 in carcinomas of the small intestine

Carcinomas of the small intestine are rare, but the risk is greatly increased in patients with hereditary nonpolyposis colorectal cancer (HNPCC) due to an inherited mismatch repair (MMR) gene mutation, most commonly affecting the genes MLH1 or MSH2. Defective MMR is characterized by microsatellite instability (MSI) and loss of MMR protein expression in the tumor tissue. However, a subset of several sporadic tumor types, including about 15% of colon cancers, also evolve through defective MMR.

Rhinoviruses Are a Major Cause of Wheezing and Hospitalization in Children Less Than 2 Years of Age

Background: Human rhinoviruses (HRV) are now considered major respiratory pathogens. We sought to determine whether HRV are a cause of wheezing and/or hospitalization in children <2 years old. Methods: A polymerase chain reaction assay was used to screen for HRV infection in 4 categories of children <2 years old: (1) with symptoms of respiratory tract disease without wheezing; (2) with wheezing with or without other symptoms; (3) who were asymptomatic and; (4) who had a respiratory specimen submitted to a diagnostic laboratory. All specimens were collected between January and December 2004. Phylogenetic analyses were performed on most HRV isolates. Results: Twenty-eight (17%) of 165 children with symptoms of respiratory infection without wheezing; 21 (26.3%) of 80 children with wheezing; 3 (3%) of 93 asymptomatic children; and 47 (23.3%) of 202 children with specimens submitted to the diagnostic laboratory tested positive for HRV. The difference between the rates of infection in the asymptomatic group and in each of the 3 other categories was statistically significant (P ≤ 0.01). Among HRV-positive children with samples submitted to the diagnostic laboratory, 55% were hospitalized, which was similar to that observed for respiratory syncytial virus (52.7%) among children of a similar age group and time period (P = 0.85). Diverse groups of HRV were circulating during the 1-year study period. Conclusions: HRV are important pathogens among children <2 years old and are responsible for a significant proportion of wheezing this age group. The hospitalization rates of HRV-positive children seem to be similar to that of respiratory syncytial virus.

Osimertinib Responses After Disease Progression in Patients Who Had Been Receiving Rociletinib

Osimertinib Responses After Disease Progression in Patients Who Had Been Receiving Rociletinib Third-generation EGFR tyrosine kinase inhibitors (TKIs) that block activating EGFR mutations and the T790M resistance mutation yield marked responses among patients with EGFR mutation–positive lung cancer and acquired resistance to initial TKIs.1,2 Osimertinib (formerly AZD9291) was recently approved by the US Food and Drug Administration, and rociletinib (formerly CO-1686) is under regulatory consideration. Little is known about using third-generation EGFR inhibitors sequentially.

Epidermal Growth Factor Receptor-Mutant Lung Cancer: New Drugs, New Resistance Mechanisms, and Future Treatment Options.

AbstractEpidermal growth factor receptor (EGFR) mutations define a subset of non–small cell lung cancers that are sensitive to EGFR-targeted tyrosine kinase inhibitors (TKIs). Treatment with EGFR TKIs improves outcomes for patients whose tumors harbor these mutations, but their efficacy is limited by the development of acquired resistance. The secondary gatekeeper mutation, T790M, is the most common resistance mechanism observed in patients who progress on erlotinib and gefitinib, and a new class of drugs has recently been developed to target mutant EGFR and T790M. Here, we review the latest data with each generation of EGFR inhibitors and discuss emerging resistance mechanisms that have been observed in patients who have progressed on the latest class of EGFR TKIs. Looking ahead, combination treatment strategies in the frontline and resistant setting may be required to promote more durable responses and delay the development of resistance, and longitudinal analyses of plasma circulating tumor DNA may allow for earlier detection of emerging resistance mutations.