Tumor-intrinsic expression of the autophagy gene Atg16l1 suppresses anti-tumor immunity in colorectal cancer.

Microsatellite-stable colorectal cancer (MSS-CRC) is highly refractory to immunotherapy. Understanding tumor-intrinsic determinants of immunotherapy resistance is critical to improve MSS-CRC patient outcomes. Here, we demonstrate that high tumor expression of the core autophagy gene ATG16L1 is associated with poor clinical response to anti-PD-L1 therapy in KRAS-mutant tumors from IMblaze370 (NCT02788279), a large phase III clinical trial of atezolizumab (anti-PD-L1) in advanced metastatic MSS-CRC. Deletion of Atg16l1 in engineered murine colon cancer organoids inhibits tumor growth in primary (colon) and metastatic (liver and lung) niches in syngeneic female hosts, primarily due to increased sensitivity to IFN-γ-mediated immune pressure. ATG16L1 deficiency enhances programmed cell death of colon cancer organoids induced by IFN-γ and TNF, thus increasing their sensitivity to host immunity. In parallel, ATG16L1 deficiency reduces tumor stem-like populations in vivo independently of adaptive immune pressure. This work reveals autophagy as a clinically relevant mechanism of immune evasion and tumor fitness in MSS-CRC and provides a rationale for autophagy inhibition to boost immunotherapy responses in the clinic.

Ipatasertib plus paclitaxel for PIK3CA/AKT1/PTEN-altered hormone receptor-positive HER2-negative advanced breast cancer: primary results from cohort B of the IPATunity130 randomized phase 3 trial.

PURPOSE: PI3K/AKT pathway alterations are frequent in hormone receptor-positive (HR+) breast cancers. IPATunity130 Cohort B investigated ipatasertib-paclitaxel in PI3K pathway-mutant HR+ unresectable locally advanced/metastatic breast cancer (aBC). METHODS: Cohort B of the randomized, double-blind, placebo-controlled, phase 3 IPATunity130 trial enrolled patients with HR+ HER2-negative PIK3CA/AKT1/PTEN-altered measurable aBC who were considered inappropriate for endocrine-based therapy (demonstrated insensitivity to endocrine therapy or visceral crisis) and were candidates for taxane monotherapy. Patients with prior chemotherapy for aBC or relapse < 1 year since (neo)adjuvant chemotherapy were ineligible. Patients were randomized 2:1 to ipatasertib (400 mg, days 1-21) or placebo, plus paclitaxel (80 mg/m2, days 1, 8, 15), every 28 days until disease progression or unacceptable toxicity. The primary endpoint was investigator-assessed progression-free survival (PFS). RESULTS: Overall, 146 patients were randomized to ipatasertib-paclitaxel and 76 to placebo-paclitaxel. In both arms, median investigator-assessed PFS was 9.3 months (hazard ratio, 1.00, 95% CI 0.71-1.40) and the objective response rate was 47%. Median paclitaxel duration was 6.9 versus 8.8 months in the ipatasertib-paclitaxel versus placebo-paclitaxel arms, respectively; median ipatasertib/placebo duration was 8.0 versus 9.1 months, respectively. The most common grade ≥ 3 adverse events were diarrhea (12% with ipatasertib-paclitaxel vs 1% with placebo-paclitaxel), neutrophil count decreased (9% vs 7%), neutropenia (8% vs 9%), peripheral neuropathy (7% vs 3%), peripheral sensory neuropathy (3% vs 5%) and hypertension (1% vs 5%). CONCLUSION: Adding ipatasertib to paclitaxel did not improve efficacy in PIK3CA/AKT1/PTEN-altered HR+ HER2-negative aBC. The ipatasertib-paclitaxel safety profile was consistent with each agent's known adverse effects. Trial registration NCT03337724.

Functional Mapping of AKT Signaling and Biomarkers of Response from the FAIRLANE Trial of Neoadjuvant Ipatasertib plus Paclitaxel for Triple-Negative Breast Cancer.

PURPOSE: Despite extensive genomic and transcriptomic profiling, it remains unknown how signaling pathways are differentially activated and how tumors are differentially sensitized to certain perturbations. Here, we aim to characterize AKT signaling activity and its association with other genomic or IHC-based PI3K/AKT pathway biomarkers as well as the clinical activity of ipatasertib (AKT inhibitor) in the FAIRLANE trial. EXPERIMENTAL DESIGN: In FAIRLANE, 151 patients with early triple-negative breast cancer (TNBC) were randomized 1:1 to receive paclitaxel with ipatasertib or placebo for 12 weeks prior to surgery. Adding ipatasertib did not increase pathologic complete response rate and numerically improved overall response rate by MRI. We used reverse-phase protein microarrays (RPPA) to examine the total level and/or phosphorylation states of over 100 proteins in various signaling or cell processes including PI3K/AKT and mTOR signaling. One hundred and twenty-five baseline and 127 on-treatment samples were evaluable by RPPA, with 110 paired samples at both time points. RESULTS: Tumors with genomic/protein alterations in PIK3CA/AKT1/PTEN were associated with higher levels of AKT phosphorylation. In addition, phosphorylated AKT (pAKT) levels exhibited a significant association with enriched clinical benefit of ipatasertib, and identified patients who received benefit in the absence of PIK3CA/AKT1/PTEN alterations. Ipatasertib treatment led to a downregulation of AKT/mTORC1 signaling, which was more pronounced among the tumors with PIK3CA/AKT1/PTEN alterations or among the responders to the treatment. CONCLUSIONS: We showed that the high baseline pAKT levels are associated with the alterations of PI3K/AKT pathway components and enriched benefit of ipatasertib in TNBC.

Final results of the double-blind placebo-controlled randomized phase 2 LOTUS trial of first-line ipatasertib plus paclitaxel for inoperable locally advanced/metastatic triple-negative breast cancer.

PURPOSE: In LOTUS (NCT02162719), adding the oral AKT inhibitor ipatasertib to first-line paclitaxel for locally advanced/metastatic triple-negative breast cancer (aTNBC) improved progression-free survival (PFS; primary endpoint), with an enhanced effect in patients with PIK3CA/AKT1/PTEN-altered tumors (FoundationOne next-generation sequencing [NGS] assay). We report final overall survival (OS) results. METHODS: Eligible patients had measurable previously untreated aTNBC. Patients were stratified by prior (neo)adjuvant therapy, chemotherapy-free interval, and tumor immunohistochemistry PTEN status, and were randomized 1:1 to paclitaxel 80 mg/m2 (days 1, 8, 15) plus ipatasertib 400 mg or placebo (days 1-21) every 28 days until disease progression or unacceptable toxicity. OS (intent-to-treat [ITT], immunohistochemistry PTEN-low, and PI3K/AKT pathway-activated [NGS PIK3CA/AKT1/PTEN-altered] populations) was a secondary endpoint. RESULTS: Median follow-up was 19.0 versus 16.0 months in the ipatasertib-paclitaxel versus placebo-paclitaxel arms, respectively. In the ITT population (n = 124), median OS was numerically longer with ipatasertib-paclitaxel than placebo-paclitaxel (hazard ratio 0.80, 95% CI 0.50-1.28; median 25.8 vs 16.9 months, respectively; 1-year OS 83% vs 68%). Likewise, median OS favored ipatasertib-paclitaxel in the PTEN-low (n = 48; 23.1 vs 15.8 months; hazard ratio 0.83) and PIK3CA/AKT1/PTEN-altered (n = 42; 25.8 vs 22.1 months; hazard ratio 1.13) subgroups. The ipatasertib-paclitaxel safety profile was unchanged. CONCLUSIONS: Final OS results show a numerical trend favoring ipatasertib-paclitaxel and median OS exceeding 2 years with ipatasertib-paclitaxel. Overall, results are consistent with the reported PFS benefit; interpretation within biomarker-defined subgroups is complicated by small sample sizes and TNBC heterogeneity.

Ipatasertib plus abiraterone and prednisolone in metastatic castration-resistant prostate cancer (IPATential150): a multicentre, randomised, double-blind, phase 3 trial.

BACKGROUND: The PI3K/AKT and androgen-receptor pathways are dysregulated in metastatic castration-resistant prostate cancers (mCRPCs); tumours with functional PTEN-loss status have hyperactivated AKT signalling. Dual pathway inhibition with AKT inhibitor ipatasertib plus abiraterone might have greater benefit than abiraterone alone. We aimed to compare ipatasertib plus abiraterone with placebo plus abiraterone in patients with previously untreated mCRPC with or without tumour PTEN loss. METHODS: We did a randomised, double-blind, phase 3 trial at 200 sites across 26 countries or regions. Patients aged 18 years or older with previously untreated asymptomatic or mildly symptomatic mCRPC who had progressive disease and Eastern Collaborative Oncology Group performance status of 0 or 1 were randomly assigned (1:1; permuted block method) to receive ipatasertib (400 mg once daily orally) plus abiraterone (1000 mg once daily orally) and prednisolone (5 mg twice a day orally) or placebo plus abiraterone and prednisolone (with the same dosing schedule). Patients received study treatment until disease progression, intolerable toxicity, withdrawal from the study, or study completion. Stratification factors were previous taxane-based therapy for hormone-sensitive prostate cancer, type of progression, presence of visceral metastasis, and tumour PTEN-loss status by immunohistochemistry. Patients, investigators, and the study sponsor were masked to the treatment allocation. The coprimary endpoints were investigator-assessed radiographical progression-free survival in the PTEN-loss-by-immunohistochemistry population and in the intention-to-treat population. This study is ongoing and is registered with ClinicalTrials.gov, NCT03072238. FINDINGS: Between June 30, 2017, and Jan 17, 2019, 1611 patients were screened for eligibility and 1101 (68%) were enrolled; 554 (50%) were assigned to the placebo-abiraterone group and 547 (50%) to the ipatasertib-abiraterone group. At data cutoff (March 16, 2020), median follow-up duration was 19 months (range 0-33). In the 521 (47%) patients who had tumours with PTEN loss by immunohistochemistry (261 in the placebo-abiraterone group and 260 in the ipatasertib-abiraterone group), median radiographical progression-free survival was 16·5 months (95% CI 13·9-17·0) in the placebo-abiraterone group and 18·5 months (16·3-22·1) in the ipatasertib-abiraterone group (hazard ratio [HR] 0·77 [95% CI 0·61-0·98]; p=0·034; significant at α=0·04). In the intention-to-treat population, median progression-free survival was 16·6 months (95% CI 15·6-19·1) in the placebo-abiraterone group and 19·2 months (16·5-22·3) in the ipatasertib-abiraterone group (HR 0·84 [95% CI 0·71-0·99]; p=0·043; not significant at α=0·01). Grade 3 or higher adverse events occurred in 213 (39%) of 546 patients in the placebo-abiraterone group and in 386 (70%) of 551 patients in the ipatasertib-abiraterone group; adverse events leading to discontinuation of placebo or ipatasertib occurred in 28 (5%) in the placebo-abiraterone group and 116 (21%) in the ipatasertib-abiraterone group. Deaths due to adverse events deemed related to treatment occurred in two patients (<1%; acute myocardial infarction [n=1] and lower respiratory tract infection [n=1]) in the placebo-abiraterone group and in two patients (<1%; hyperglycaemia [n=1] and chemical pneumonitis [n=1]) in the ipastasertb-abiraterone group. INTERPRETATION: Ipatasertib plus abiraterone significantly improved radiographical progression-free survival compared with placebo plus abiraterone among patients with mCRPC with PTEN-loss tumours, but there was no significant difference between the groups in the intention-to-treat population. Adverse events were consistent with the known safety profiles of each agent. These data suggest that combined AKT and androgen-receptor signalling pathway inhibition with ipatasertib and abiraterone is a potential treatment for men with PTEN-loss mCRPC, a population with a poor prognosis. FUNDING: F Hoffmann-La Roche and Genentech.

Transcriptional Subtypes Resolve Tumor Heterogeneity and Identify Vulnerabilities to MEK Inhibition in Lung Adenocarcinoma.

PURPOSE: Lung adenocarcinomas comprise the largest fraction of non-small cell lung cancer, which is the leading cause of cancer-related deaths. Seventy-five percent of adenocarcinomas lack targeted therapies because of scarcity of druggable drivers. Here, we classified tumors on the basis of signaling similarities and discovered subgroups within this unmet patient population. EXPERIMENTAL DESIGN: We leveraged transcriptional data from >800 early- and advanced-stage patients. RESULTS: We identified three robust subtypes dubbed mucinous, proliferative, and mesenchymal with respective pathway phenotypes. These transcriptional states lack discrete and causative mutational etiology as evidenced by similarly distributed oncogenic drivers, including KRAS and EGFR. The subtypes capture heterogeneity even among tumors lacking known oncogenic drivers. Paired multi-regional intratumoral biopsies demonstrated unified subtypes despite divergently evolved prooncogenic mutations, indicating subtype stability during selective pressure. Heterogeneity among in vitro and in vivo preclinical models is expounded by the human lung adenocarcinoma subtypes and can be leveraged to discover subtype-specific vulnerabilities. As proof of concept, we identified differential subtype response to MEK pathway inhibition in a chemical library screen of 89 lung cancer cell lines, which reproduces across model systems and a clinical trial. CONCLUSIONS: Our findings support forward translational relevance of transcriptional subtypes, where further exploration therein may improve lung adenocarcinoma treatment.See related commentary by Skoulidis, p. 913.

Circulating Tumor DNA and Biomarker Analyses From the LOTUS Randomized Trial of First-Line Ipatasertib and Paclitaxel for Metastatic Triple-Negative Breast Cancer.

PURPOSE: Combining the oral AKT inhibitor ipatasertib with paclitaxel as first-line therapy for metastatic triple-negative breast cancer significantly improved progression-free survival (PFS) in the placebo-controlled, randomized, phase II LOTUS trial, with a more pronounced effect in patients with PIK3CA/AKT1/PTEN-altered tumors. We report findings from the extensive translational research program. PATIENTS AND METHODS: Pretreatment plasma and tumor samples were evaluated for genetic alterations using FoundationACT and FoundationOne (Foundation Medicine, Cambridge, MA) hybrid capture next-generation sequencing assays, respectively. Prevalences of the most common mutations and PIK3CA/AKT1 mutation status were determined using both assays, and concordance was assessed. In longitudinal analyses, circulating tumor DNA (ctDNA) mutations were quantified in baseline and on-treatment (cycle 3, day 1 [C3D1]) samples. The relationship between outcomes and ctDNA fraction (CTF; highest variant allele frequency) and CTF ratio (C3D1 CTF to baseline CTF) was explored. RESULTS: Among 89 patients evaluable for ctDNA sequencing, 81 patients (91%) had 149 detectable mutations. There was high agreement between plasma- and tissue-based sequencing for known or likely short variant mutations but not amplifications. There was 100% concordance between ctDNA and tissue sequencing in patients with activating PIK3CA or AKT1 mutations. High baseline CTF was associated with shorter PFS in both treatment arms. Longitudinal analyses showed more favorable outcomes with lower absolute CTF at C3D1 and, to a lesser extent, greater CTF decreases. CONCLUSION: These results suggest that plasma ctDNA sequencing may allow reliable and convenient assessment of prognosis and identification of genetic markers associated with increased benefit from ipatasertib. On-treatment CTF showed a meaningful association with objective response and PFS.

Robust network inference using response logic.

MOTIVATION: A major challenge in molecular and cellular biology is to map out the regulatory networks of cells. As regulatory interactions can typically not be directly observed experimentally, various computational methods have been proposed to disentangling direct and indirect effects. Most of these rely on assumptions that are rarely met or cannot be adapted to a given context. RESULTS: We present a network inference method that is based on a simple response logic with minimal presumptions. It requires that we can experimentally observe whether or not some of the system's components respond to perturbations of some other components, and then identifies the directed networks that most accurately account for the observed propagation of the signal. To cope with the intractable number of possible networks, we developed a logic programming approach that can infer networks of hundreds of nodes, while being robust to noisy, heterogeneous or missing data. This allows to directly integrate prior network knowledge and additional constraints such as sparsity. We systematically benchmark our method on KEGG pathways, and show that it outperforms existing approaches in DREAM3 and DREAM4 challenges. Applied to a novel perturbation dataset on PI3K and MAPK pathways in isogenic models of a colon cancer cell line, it generates plausible network hypotheses that explain distinct sensitivities toward various targeted inhibitors due to different PI3K mutants. AVAILABILITY AND IMPLEMENTATION: A Python/Answer Set Programming implementation can be accessed at github.com/GrossTor/response-logic. Data and analysis scripts are available at github.com/GrossTor/response-logic-projects. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Atezolizumab plus cobimetinib and vemurafenib in BRAF-mutated melanoma patients.

Melanoma treatment has progressed in the past decade with the development and approval of immune checkpoint inhibitors targeting programmed death 1 (PD-1) or its ligand (PD-L1) and cytotoxic T lymphocyte-associated antigen 4, as well as small molecule inhibitors of BRAF and/or MEK for the subgroup of patients with BRAFV600 mutations1-9. BRAF/MEK-targeted therapies have effects on the tumor microenvironment that support their combination with PD-1/PD-L1 inhibitors10-20. This phase Ib study (ClinicalTrials.gov, number NCT01656642 ) evaluated the safety and anti-tumor activity of combining atezolizumab (anti-PD-L1) with vemurafenib (BRAF inhibitor), or cobimetinib (MEK inhibitor) + vemurafenib, in patients with BRAFV600-mutated metastatic melanoma. Triple combination therapy with atezolizumab + cobimetinib + vemurafenib, after a 28-d run-in period with cobimetinib + vemurafenib, had substantial but manageable toxicity. Exploratory biomarker data show that the cobimetinib + vemurafenib run-in was associated with an increase in proliferating CD4+ T-helper cells but not with an increase in T-regulatory cells, as observed in the vemurafenib-only run-in period. The confirmed objective response rate was 71.8% (95% confidence interval 55.1-85.0). The estimated median duration of response was 17.4 months (95% confidence interval 10.6-25.3) with ongoing response in 39.3% of patients after 29.9 months of follow-up. Further investigation in a phase III trial is underway.

Genomic Features of Exceptional Response in Vemurafenib ± Cobimetinib-treated Patients with BRAF V600-mutated Metastatic Melanoma.

PURPOSE: Previous investigations identified transcriptional signatures associated with innate resistance to anti-programmed cell death protein 1 therapy in melanoma. This analysis aimed to increase understanding of the role of baseline genetic features in the variability of response to BRAF and MEK inhibitor therapy for BRAF V600-mutated metastatic melanoma. PATIENTS AND METHODS: This exploratory analysis compared genomic features, using whole-exome and RNA sequencing, of baseline tumors from patients who had complete response versus rapid progression (disease progression at first postbaseline assessment) on treatment with cobimetinib combined with vemurafenib or vemurafenib alone. Associations of gene expression with progression-free survival or overall survival were assessed by Cox proportional hazards modeling. RESULTS: Whole-exome sequencing showed that MITF and TP53 alterations were more frequent in tumors from patients with rapid progression, while NF1 alterations were more frequent in tumors from patients with complete response. However, the low frequency of alterations in any one gene precluded their characterization as drivers of response/resistance. Analysis of RNA profiles showed that expression of immune response-related genes was enriched in tumors from patients with complete response, while expression of keratinization-related genes was enriched in tumors from patients who experienced rapid progression. CONCLUSIONS: These findings suggest that enriched immune infiltration might be a shared feature favoring response to both targeted and immune therapies, while features of innate resistance to targeted and immune therapies were distinct.

Therapeutic resistance and susceptibility is shaped by cooperative multi-compartment tumor adaptation.

Emerging research suggests that multiple tumor compartments can influence treatment responsiveness and relapse, yet the search for therapeutic resistance mechanisms remains largely focused on acquired genomic alterations in cancer cells. Here we show how treatment-induced changes occur in multiple tumor compartments during tumor relapse and can reduce benefit of follow-on therapies. By using serial biopsies, next-generation sequencing, and single-cell transcriptomics, we tracked the evolution of multiple cellular compartments within individual lesions during first-line treatment response, relapse, and second-line therapeutic interventions in an autochthonous model of melanoma. We discovered that although treatment-relapsed tumors remained genetically stable, they converged on a shared resistance phenotype characterized by dramatic changes in tumor cell differentiation state, immune infiltration, and extracellular matrix (ECM) composition. Similar alterations in tumor cell differentiation were also observed in more than half of our treatment-relapsed patient tumors. Tumor cell-state changes were coincident with ECM remodeling and increased tumor stiffness, which alone was sufficient to alter tumor cell fate and reduce treatment responses in melanoma cell lines in vitro. Despite the absence of acquired mutations in the targeted pathway, resistant tumors showed significantly decreased responsiveness to second-line therapy intervention within the same pathway. The ability to preclinically model relapse and refractory settings-while capturing dynamics within and crosstalk between all relevant tumor compartments-provides a unique opportunity to better design and sequence appropriate clinical interventions.

Elevated Levels of BRAFV600 Mutant Circulating Tumor DNA and Circulating Hepatocyte Growth Factor Are Associated With Poor Prognosis in Patients With Metastatic Melanoma.

PURPOSE: We performed a retrospective exploratory analysis to evaluate the prognostic and predictive effect of two circulating biomarkers, BRAFV600 mutant circulating tumor DNA (ctDNA) and circulating hepatocyte growth factor (cHGF), in metastatic melanoma. MATERIALS AND METHODS: This study evaluated patients from BRIM-3, a phase III trial comparing vemurafenib and dacarbazine in 675 patients with BRAFV600 mutated advanced melanoma. ctDNA was measured using droplet digital polymerase chain reaction, and cHGF was measured by enzyme-linked immunosorbent assay. Overall survival (OS) was estimated using the Kaplan-Meier method, and hazard ratios (HRs) were estimated using Cox proportional hazards modeling. Partitioning analysis was used to group patients into risk categories. RESULTS: Patients with elevated levels of baseline BRAFV600 ctDNA had significantly shorter median OS than those with undetectable levels of ctDNA (vemurafenib arm, 9.9 v 21.4 months, respectively, and dacarbazine arm: 6.1 v 21.0 months, respectively). Median OS was also shorter in patients with high levels of cHGF compared with those with low cHGF (vemurafenib arm, 11.9 v 17.3 months, respectively, and dacarbazine arm, 6.1 v 14.4 months, respectively). In a multivariable proportional hazards model with adjustment for lactate dehydrogenase, Eastern Cooperative Oncology Group status, disease stage, and treatment, ctDNA and cHGF were both independent prognostic factors for OS, (HR, 1.75; 95% CI, 1.35 to 2.28 for high v undetectable ctDNA; HR, 1.24; 95% CI, 1.00 to 1.53 for high v low cHGF). Using partitioning analysis, we found that patients with elevated ctDNA combined with elevated cHGF constituted the highest risk group with significantly shorter OS. CONCLUSION: Here, we report that BRIM-3 patients with high levels of ctDNA and cHGF have worse OS regardless of treatment and that these factors are independent prognostic markers for metastatic melanoma.

Effects of Molecular Heterogeneity on Survival of Patients With BRAFV600-Mutated Melanoma Treated With Vemurafenib With or Without Cobimetinib in the coBRIM Study.

PURPOSE: The treatment of advanced BRAFV600-mutated melanomas with BRAF inhibitors (BRAFi) has improved survival, but the efficacy of BRAFi varies among individuals and the development of acquired resistance to BRAFi through reactivation of mitogen-activated protein kinase (MAPK) signaling is common. We performed an exploratory, retrospective analysis to investigate the effects of BRAFV600 allelic balance, coexisting oncogene mutations, cell proliferation signaling levels, and loss of PTEN expression on progression-free survival (PFS) in patients in the phase III coBRIM study, which compared the combination of the MEK inhibitor cobimetinib with the BRAFi vemurafenib versus vemurafenib as monotherapy. METHODS: Baseline tumor samples from the intention-to-treat population were analyzed by targeted deep sequencing at a median coverage of 3,600× and by immunohistochemistry for cell proliferation markers, BRAFV600E, and PTEN. The association of these biomarkers with PFS was assessed by Cox proportional hazards modeling. Gene expression in relation to loss of PTEN was profiled by RNA sequencing in 205 patient samples and 42 BRAFV600-mutated melanoma cell lines. RESULTS: Neither BRAFV600 allelic balance nor coexisting mutations in the RAS/RAF/RTK pathway affected PFS in either treatment group. Increased baseline MAPK signaling and cell proliferation did not affect PFS in patients treated with cobimetinib combined with vemurafenib. PTEN loss was associated with reduced PFS in patients treated with vemurafenib alone but not in patients treated with cobimetinib combined with vemurafenib. CONCLUSION: Deeper inhibition of the MAPK pathway through targeting of both MEK and BRAF may override the effects of tumor heterogeneity and improve PFS in all patients with advanced BRAFV600 melanoma.

Association of programmed death ligand-1 (PD-L1) expression with treatment outcomes in patients with BRAF mutation-positive melanoma treated with vemurafenib or cobimetinib combined with vemurafenib.

The prognostic significance of programmed death ligand-1 (PD-L1) on treatment outcomes in patients receiving BRAF with or without MEK inhibitors is not well understood. This retrospective exploratory analysis evaluated the association of tumour PD-L1 expression with progression-free survival (PFS) and overall survival (OS) among 210 patients in the coBRIM trial treated with cobimetinib plus vemurafenib or placebo plus vemurafenib. In the vemurafenib cohort, there was a trend of increased PFS and OS in those with PD-L1+ melanoma, with hazard ratios (HRs; PD-L1+ vs. PD-L1- ) of 0.70 (95% CI, 0.46-1.07) and 0.69 (95% CI, 0.42-1.13) for PFS and OS, respectively. However, in patients treated with cobimetinib plus vemurafenib, a similar trend was not observed with HRs (PD-L1+ versus PD-L1- ) of 1.04 (95% CI, 0.66-1.68) and 0.94 (95% CI, 0.57-1.57) for PFS and OS, respectively. The combination cobimetinib plus vemurafenib appears to overcome the poor prognosis associated with low PD-L1 expression.

Ipatasertib plus paclitaxel versus placebo plus paclitaxel as first-line therapy for metastatic triple-negative breast cancer (LOTUS): a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial.

BACKGROUND: The oral AKT inhibitor ipatasertib is being investigated in cancers with a high prevalence of PI3K/AKT pathway activation, including triple-negative breast cancer. The LOTUS trial investigated the addition of ipatasertib to paclitaxel as first-line therapy for triple-negative breast cancer. METHODS: In this randomised, placebo-controlled, double-blind, phase 2 trial, women aged 18 years or older with measurable, inoperable, locally advanced or metastatic triple-negative breast cancer previously untreated with systemic therapy were recruited from 44 hospitals in South Korea, the USA, France, Spain, Taiwan, Singapore, Italy, and Belgium. Enrolled patients were randomly assigned (1:1) to receive intravenous paclitaxel 80 mg/m2 (days 1, 8, 15) with either ipatasertib 400 mg or placebo once per day (days 1-21) every 28 days until disease progression or unacceptable toxicity. Randomisation was by stratified permuted blocks (block size of four) using an interactive web-response system with three stratification criteria: previous (neo)adjuvant therapy, chemotherapy-free interval, and tumour PTEN status. The co-primary endpoints were progression-free survival in the intention-to-treat population and progression-free survival in the PTEN-low (by immunohistochemistry) population. This ongoing trial is registered with ClinicalTrials.gov (NCT02162719). FINDINGS: Between Sept 2, 2014, and Feb 4, 2016, 166 patients were assessed for eligibility and 124 patients were enrolled and randomly assigned to paclitaxel plus ipatasertib (n=62) or paclitaxel plus placebo (n=62). Median follow-up was 10·4 months (IQR 6·5-14·1) in the ipatasertib group and 10·2 months (6·0-13·6) in the placebo group. Median progression-free survival in the intention-to-treat population was 6·2 months (95% CI 3·8-9·0) with ipatasertib versus 4·9 months (3·6-5·4) with placebo (stratified hazard ratio [HR] 0·60, 95% CI 0·37-0·98; p=0·037) and in the 48 patients with PTEN-low tumours, median progression-free survival was 6·2 months (95% CI 3·6-9·1) with ipatasertib versus 3·7 months (1·9-7·3) with placebo (stratified HR 0·59, 95% CI 0·26-1·32, p=0·18). The most common grade 3 or worse adverse events were diarrhoea (14 [23%] of 61 ipatasertib-treated patients vs none of 62 placebo-treated patients), neutrophil count decreased (five [8%] vs four [6%]), and neutropenia (six [10%] vs one [2%]). No colitis, grade 4 diarrhoea, or treatment-related deaths were reported with ipatasertib. One treatment-related death occurred in the placebo group. Serious adverse events were reported in 17 (28%) of 61 patients in the ipatasertib group and nine (15%) of 62 patients in the placebo group. INTERPRETATION: Progression-free survival was longer in patients who received ipatasertib than in those who received placebo. To our knowledge, these are the first results supporting AKT-targeted therapy for triple-negative breast cancer. Ipatasertib warrants further investigation for the treatment of triple-negative breast cancer. FUNDING: F Hoffmann-La Roche.

Gene Expression Profiling in BRAF-Mutated Melanoma Reveals Patient Subgroups with Poor Outcomes to Vemurafenib That May Be Overcome by Cobimetinib Plus Vemurafenib.

Purpose: The association of tumor gene expression profiles with progression-free survival (PFS) outcomes in patients with BRAFV600-mutated melanoma treated with vemurafenib or cobimetinib combined with vemurafenib was evaluated.Experimental Design: Gene expression of archival tumor samples from patients in four trials (BRIM-2, BRIM-3, BRIM-7, and coBRIM) was evaluated. Genes significantly associated with PFS (P < 0.05) were identified by univariate Cox proportional hazards modeling, then subjected to unsupervised hierarchical clustering, principal component analysis, and recursive partitioning to develop optimized gene signatures.Results: Forty-six genes were identified as significantly associated with PFS in both BRIM-2 (n = 63) and the vemurafenib arm of BRIM-3 (n = 160). Two distinct signatures were identified: cell cycle and immune. Among vemurafenib-treated patients, the cell-cycle signature was associated with shortened PFS compared with the immune signature in the BRIM-2/BRIM-3 training set [hazard ratio (HR) 1.8; 95% confidence interval (CI), 1.3-2.6, P = 0.0001] and in the coBRIM validation set (n = 101; HR, 1.6; 95% CI, 1.0-2.5; P = 0.08). The adverse impact of the cell-cycle signature on PFS was not observed in patients treated with cobimetinib combined with vemurafenib (n = 99; HR, 1.1; 95% CI, 0.7-1.8; P = 0.66).Conclusions: In vemurafenib-treated patients, the cell-cycle gene signature was associated with shorter PFS. However, in cobimetinib combined with vemurafenib-treated patients, both cell cycle and immune signature subgroups had comparable PFS. Cobimetinib combined with vemurafenib may abrogate the adverse impact of the cell-cycle signature. Clin Cancer Res; 23(17); 5238-45. ©2017 AACR.

Activation Mechanism of Oncogenic Deletion Mutations in BRAF, EGFR, and HER2.

Activating mutations in protein kinases drive many cancers. While how recurring point mutations affect kinase activity has been described, the effect of in-frame deletions is not well understood. We show that oncogenic deletions within the ß3-αC loop of HER2 and BRAF are analogous to the recurrent EGFR exon 19 deletions. We identify pancreatic carcinomas with BRAF deletions mutually exclusive with KRAS mutations. Crystal structures of BRAF deletions reveal the truncated loop restrains αC in an active "in" conformation, imparting resistance to inhibitors like vemurafenib that bind the αC "out" conformation. Characterization of loop length explains the prevalence of five amino acid deletions in BRAF, EGFR, and HER2 and highlights the importance of this region for kinase activity and inhibitor efficacy.

Combined targeting of FGFR2 and mTOR by ponatinib and ridaforolimus results in synergistic antitumor activity in FGFR2 mutant endometrial cancer models.

PURPOSE: Activating mutations in FGFR2 have been identified as potential therapeutic targets in endometrial cancer, typically occurring alongside genetic alterations that disrupt the mTOR pathway, such as PTEN loss. These observations suggest that the mTOR pathway may act in concert with oncogenic FGFR2 to drive endometrial cancer growth in a subset of patients. The aim of this study was to examine the therapeutic potential of a rational drug combination based on the simultaneous targeting of mutant-FGFR2 and mTOR-driven signaling pathways in endometrial cancer cells. METHODS: Ponatinib is an oral multitargeted kinase inhibitor that potently inhibits all 4 members of the FGFR family. Ridaforolimus is a selective inhibitor of mTOR that has demonstrated positive clinical activity in endometrial cancer. The combinatorial effects of ponatinib and ridaforolimus on growth of endometrial cancer models, and their modes of action, were evaluated in vitro and in vivo. RESULTS: The combination of ponatinib and ridaforolimus had a synergistic effect on the in vitro growth of endometrial lines bearing an activating FGFR2 mutation, irrespective of PTEN status. Concomitant inhibition of both FGFR2 and mTOR signaling pathways was observed, with simultaneous blockade resulting in enhanced cell cycle arrest. Ponatinib and ridaforolimus each demonstrated inhibition of tumor growth in vivo, but dual inhibition by the combination of agents resulted in superior efficacy and induced tumor regression in an endometrial xenograft. CONCLUSIONS: These encouraging preclinical findings suggest the inhibition of both FGFR2 and mTOR by the ponatinib-ridaforolimus combination may provide a new therapeutic strategy to treat advanced endometrial cancers with dual pathway dysregulation.