2021
Molecular correlates of response to eribulin and pembrolizumab in hormone receptor-positive metastatic breast cancer
Keenan TE, Guerriero JL, Barroso-Sousa R, Li T, O’Meara T, Giobbie-Hurder A, Tayob N, Hu J, Severgnini M, Agudo J, Vaz-Luis I, Anderson L, Attaya V, Park J, Conway J, He MX, Reardon B, Shannon E, Wulf G, Spring LM, Jeselsohn R, Krop I, Lin NU, Partridge A, Winer EP, Mittendorf EA, Liu D, Van Allen EM, Tolaney SM. Molecular correlates of response to eribulin and pembrolizumab in hormone receptor-positive metastatic breast cancer. Nature Communications 2021, 12: 5563. PMID: 34548479, PMCID: PMC8455578, DOI: 10.1038/s41467-021-25769-z.Peer-Reviewed Original ResearchMeSH KeywordsAdultAgedAntibodies, Monoclonal, HumanizedAntigen PresentationAntineoplastic Combined Chemotherapy ProtocolsB7-H1 AntigenBreast NeoplasmsCytokinesDrug Resistance, NeoplasmEstrogensFemaleFuransGene Expression ProfilingGenetic HeterogeneityGenome, HumanGenomicsHumansImmune Checkpoint InhibitorsKetonesLymphocytes, Tumor-InfiltratingMaleMiddle AgedMutationNeoplasm MetastasisReceptors, EstrogenReceptors, ProgesteroneSignal TransductionSurvival RateTreatment OutcomeConceptsImmune checkpoint inhibitorsBreast cancerHormone receptor-positive metastatic breast cancerHormone receptor-positive breast cancerFinal overall survival resultsRandomized phase 2 trialReceptor-positive breast cancerMinimal therapeutic effectPhase 2 trialMetastatic breast cancerOverall survival resultsPre-treatment tumorsCheckpoint inhibitorsCytokine changesICI responseCombination therapyImmune infiltrationImmunoregulatory cytokinesSurvival resultsAntigen presentationTherapeutic effectTherapeutic validationCancerMolecular correlatesTumor heterogeneityAdjuvant Pertuzumab and Trastuzumab in Early HER2-Positive Breast Cancer in the APHINITY Trial: 6 Years' Follow-Up
Piccart M, Procter M, Fumagalli D, de Azambuja E, Clark E, Ewer MS, Restuccia E, Jerusalem G, Dent S, Reaby L, Bonnefoi H, Krop I, Liu TW, Pieńkowski T, Toi M, Wilcken N, Andersson M, Im YH, Tseng LM, Lueck HJ, Colleoni M, Monturus E, Sicoe M, Guillaume S, Bines J, Gelber RD, Viale G, Thomssen C. Adjuvant Pertuzumab and Trastuzumab in Early HER2-Positive Breast Cancer in the APHINITY Trial: 6 Years' Follow-Up. Journal Of Clinical Oncology 2021, 39: 1448-1457. PMID: 33539215, DOI: 10.1200/jco.20.01204.Peer-Reviewed Original ResearchConceptsInvasive disease-free survivalBreast cancerHazard ratioOverall survivalHigh-risk node-negative breast cancerEarly HER2-positive breast cancerHER2-positive early breast cancerNode-negative breast cancerHuman epidermal growth factor receptor 2HER2-positive breast cancerEpidermal growth factor receptor 2HR-negative diseaseHR-positive diseaseInterim overall survivalNode-negative cohortNode-positive cohortPrimary cardiac eventsSix-year OSStandard adjuvant chemotherapyDisease-free survivalNew safety signalsEarly breast cancerGrowth factor receptor 2Standard adjuvant therapyPositive breast cancer
2020
A Randomized Placebo Controlled Phase II Trial Evaluating Exemestane with or without Enzalutamide in Patients with Hormone Receptor–Positive Breast Cancer
Krop I, Abramson V, Colleoni M, Traina T, Holmes F, Garcia-Estevez L, Hart L, Awada A, Zamagni C, Morris PG, Schwartzberg L, Chan S, Gucalp A, Biganzoli L, Steinberg J, Sica L, Trudeau M, Markova D, Tarazi J, Zhu Z, O'Brien T, Kelly C, Winer E, Yardley D. A Randomized Placebo Controlled Phase II Trial Evaluating Exemestane with or without Enzalutamide in Patients with Hormone Receptor–Positive Breast Cancer. Clinical Cancer Research 2020, 26: 6149-6157. PMID: 32988969, DOI: 10.1158/1078-0432.ccr-20-1693.Peer-Reviewed Original ResearchConceptsProgression-free survivalHormone receptor-positive breast cancerReceptor-positive breast cancerPhase II trialEndocrine therapyBreast cancerII trialAR mRNACohort 1Higher AR mRNA levelsLower ESR1 mRNA levelsET-naïve patientsGrade adverse eventsPrior endocrine therapyMetastatic breast cancerAndrogen receptor inhibitorMRNA levelsAR mRNA levelsESR1 mRNA levelsEnzalutamide armITT populationTreat populationAdvanced diseasePrimary endpointAdverse eventsPhase 2 study of buparlisib (BKM120), a pan-class I PI3K inhibitor, in patients with metastatic triple-negative breast cancer
Garrido-Castro AC, Saura C, Barroso-Sousa R, Guo H, Ciruelos E, Bermejo B, Gavilá J, Serra V, Prat A, Paré L, Céliz P, Villagrasa P, Li Y, Savoie J, Xu Z, Arteaga CL, Krop IE, Solit DB, Mills GB, Cantley LC, Winer EP, Lin NU, Rodon J. Phase 2 study of buparlisib (BKM120), a pan-class I PI3K inhibitor, in patients with metastatic triple-negative breast cancer. Breast Cancer Research 2020, 22: 120. PMID: 33138866, PMCID: PMC7607628, DOI: 10.1186/s13058-020-01354-y.Peer-Reviewed Original ResearchMeSH KeywordsAdultAgedAminopyridinesAntineoplastic Combined Chemotherapy ProtocolsClass I Phosphatidylinositol 3-KinasesDisease ProgressionFemaleHigh-Throughput Nucleotide SequencingHumansMiddle AgedMorpholinesNeoplasm MetastasisPatient SafetyProtein Kinase InhibitorsProteomicsResponse Evaluation Criteria in Solid TumorsSurvival RateTreatment OutcomeTriple Negative Breast NeoplasmsConceptsTriple-negative breast cancerProgression-free survivalPan-class I PI3K inhibitorMetastatic triple-negative breast cancerStable diseasePhase 2 studyBreast cancerOverall survivalPI3K inhibitorsPI3K pathwayPartial responseComplete responseClinical benefitSingle-arm phase 2 studyTriple-negative metastatic breast cancerMedian progression-free survivalK inhibitorsClinical benefit rateEfficacy of buparlisibK pathwayFrequent adverse eventsMedian overall survivalPercent of patientsMetastatic breast cancerSubset of patientsTumor Mutational Burden and PTEN Alterations as Molecular Correlates of Response to PD-1/L1 Blockade in Metastatic Triple-Negative Breast Cancer
Barroso-Sousa R, Keenan TE, Pernas S, Exman P, Jain E, Garrido-Castro AC, Hughes M, Bychkovsky B, Umeton R, Files JL, Lindeman NI, MacConaill LE, Hodi FS, Krop IE, Dillon D, Winer EP, Wagle N, Lin NU, Mittendorf EA, Van Allen EM, Tolaney SM. Tumor Mutational Burden and PTEN Alterations as Molecular Correlates of Response to PD-1/L1 Blockade in Metastatic Triple-Negative Breast Cancer. Clinical Cancer Research 2020, 26: 2565-2572. PMID: 32019858, PMCID: PMC7269810, DOI: 10.1158/1078-0432.ccr-19-3507.Peer-Reviewed Original ResearchConceptsMetastatic triple-negative breast cancerHigh tumor mutational burdenProgression-free survivalTumor mutational burdenObjective response rateImmune checkpoint inhibitorsAnti-PD-1/L1 therapyTriple-negative breast cancerOverall survivalL1 therapyPD-L1Breast cancerMutational burdenLow objective response rateLonger progression-free survivalShorter progression-free survivalDana-Farber Cancer InstituteTumor genomic featuresShorter overall survivalMutations/megabaseCheckpoint inhibitorsVisceral metastasesL1 blockadePerformance statusPrior linesSensitive Detection of Minimal Residual Disease in Patients Treated for Early-Stage Breast Cancer
Parsons HA, Rhoades J, Reed SC, Gydush G, Ram P, Exman P, Xiong K, Lo CC, Li T, Fleharty M, Kirkner GJ, Rotem D, Cohen O, Yu F, Fitarelli-Kiehl M, Leong KW, Hughes ME, Rosenberg SM, Collins LC, Miller KD, Blumenstiel B, Trippa L, Cibulskis C, Neuberg DS, DeFelice M, Freeman SS, Lennon NJ, Wagle N, Ha G, Stover DG, Choudhury AD, Getz G, Winer EP, Meyerson M, Lin NU, Krop I, Love JC, Makrigiorgos GM, Partridge AH, Mayer EL, Golub TR, Adalsteinsson VA. Sensitive Detection of Minimal Residual Disease in Patients Treated for Early-Stage Breast Cancer. Clinical Cancer Research 2020, 26: 2556-2564. PMID: 32170028, PMCID: PMC7654718, DOI: 10.1158/1078-0432.ccr-19-3005.Peer-Reviewed Original ResearchConceptsMinimal residual diseaseMetastatic breast cancerDigital droplet PCRBreast cancerTumor mutationsResidual diseaseMRD detectionEarly-stage breast cancerCurative-intent treatmentCohort of patientsEarly-stage diseaseMedian lead timeClinical data collectionWhole-exome sequencingMRD testFirst positive sampleDistant recurrenceMost patientsMetastatic diagnosisStage 0PatientsPlasma samplingClinical sensitivityPatient-specific mutationsCfDNA samples
2019
Trastuzumab deruxtecan (DS-8201a) in patients with advanced HER2-positive breast cancer previously treated with trastuzumab emtansine: a dose-expansion, phase 1 study
Tamura K, Tsurutani J, Takahashi S, Iwata H, Krop IE, Redfern C, Sagara Y, Doi T, Park H, Murthy RK, Redman RA, Jikoh T, Lee C, Sugihara M, Shahidi J, Yver A, Modi S. Trastuzumab deruxtecan (DS-8201a) in patients with advanced HER2-positive breast cancer previously treated with trastuzumab emtansine: a dose-expansion, phase 1 study. The Lancet Oncology 2019, 20: 816-826. PMID: 31047803, DOI: 10.1016/s1470-2045(19)30097-x.Peer-Reviewed Original ResearchMeSH KeywordsAdo-Trastuzumab EmtansineAgedAntibodies, Monoclonal, HumanizedAntineoplastic Agents, ImmunologicalBreast NeoplasmsCamptothecinFemaleFollow-Up StudiesHumansImmunoconjugatesMaximum Tolerated DoseMiddle AgedPrognosisReceptor, ErbB-2Salvage TherapySurvival RateTissue DistributionTrastuzumabConceptsHER2-positive breast cancerTreatment-emergent adverse eventsAdvanced-stage breast cancerTrastuzumab emtansine treatmentTrastuzumab deruxtecanPhase 1 trialBreast cancerAdverse eventsProgressive diseaseSerious treatment-emergent adverse eventsWorse treatment-emergent adverse eventsAdvanced HER2-positive breast cancerSolid tumorsTopoisomerase I inhibitor payloadFrequent grade 3Grade 3 eventsTreatment-related deathsManageable safety profileAdvanced solid tumorsMultiple-dose studyPhase 1 studyInterstitial lung diseaseWithdrawal of consentWhite blood cellsYears of ageTBCRC 022: A Phase II Trial of Neratinib and Capecitabine for Patients With Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer and Brain Metastases
Freedman RA, Gelman RS, Anders CK, Melisko ME, Parsons HA, Cropp AM, Silvestri K, Cotter CM, Componeschi KP, Marte JM, Connolly RM, Moy B, Van Poznak CH, Blackwell KL, Puhalla SL, Jankowitz RC, Smith KL, Ibrahim N, Moynihan TJ, O’Sullivan C, Nangia J, Niravath P, Tung N, Pohlmann PR, Burns R, Rimawi MF, Krop IE, Wolff AC, Winer EP, Lin NU, . TBCRC 022: A Phase II Trial of Neratinib and Capecitabine for Patients With Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer and Brain Metastases. Journal Of Clinical Oncology 2019, 37: jco.18.01511. PMID: 30860945, PMCID: PMC6494354, DOI: 10.1200/jco.18.01511.Peer-Reviewed Original ResearchConceptsCNS objective response rateObjective response rateHER2-positive breast cancer brain metastasesBreast cancer brain metastasesCancer brain metastasesBrain metastasesBreast cancerCommon grade 3 toxicitiesHER2-positive brain metastasesMedian progression-free survivalHuman epidermal growth factor receptor 2Epidermal growth factor receptor 2Human epidermal growth factor receptorEfficacy of HER2Non-CNS progressionGrade 3 toxicityPrimary end pointPhase II trialProgression-free survivalGrowth factor receptor 2Positive breast cancerProgressive neurologic signsEvidence-based treatmentsFactor receptor 2Epidermal growth factor receptor
2017
Trastuzumab emtansine versus capecitabine plus lapatinib in patients with previously treated HER2-positive advanced breast cancer (EMILIA): a descriptive analysis of final overall survival results from a randomised, open-label, phase 3 trial
Diéras V, Miles D, Verma S, Pegram M, Welslau M, Baselga J, Krop IE, Blackwell K, Hoersch S, Xu J, Green M, Gianni L. Trastuzumab emtansine versus capecitabine plus lapatinib in patients with previously treated HER2-positive advanced breast cancer (EMILIA): a descriptive analysis of final overall survival results from a randomised, open-label, phase 3 trial. The Lancet Oncology 2017, 18: 732-742. PMID: 28526536, PMCID: PMC5531181, DOI: 10.1016/s1470-2045(17)30312-1.Peer-Reviewed Original ResearchMeSH KeywordsAdo-Trastuzumab EmtansineAdultAgedAged, 80 and overAnemiaAntibodies, Monoclonal, HumanizedAntineoplastic AgentsAntineoplastic Combined Chemotherapy ProtocolsAspartate AminotransferasesBreast NeoplasmsBreast Neoplasms, MaleBridged-Ring CompoundsCapecitabineDiarrheaDisease-Free SurvivalFemaleHand-Foot SyndromeHumansLapatinibMaleMaytansineMiddle AgedQuinazolinesReceptor, ErbB-2Response Evaluation Criteria in Solid TumorsRetreatmentSurvival RateTaxoidsThrombocytopeniaTrastuzumabVomitingYoung AdultConceptsWorse adverse eventsMetastatic breast cancerHER2-positive metastatic breast cancerInterim overall survival analysisProgression-free survivalOverall survival dataTrastuzumab emtansineOverall survivalAdverse eventsOverall survival analysisBreast cancerGrade 3Safety profileHER2-positive advanced breast cancerSurvival analysisFinal overall survival dataFinal overall survival resultsPalmar-plantar erythrodysaesthesia syndromeCoprimary efficacy endpointsFinal overall survivalPrevious chemotherapy regimensMedian overall survivalAdvanced breast cancerPhase 3 trialStudy drug discontinuationTrastuzumab emtansine versus treatment of physician's choice in patients with previously treated HER2-positive metastatic breast cancer (TH3RESA): final overall survival results from a randomised open-label phase 3 trial
Krop IE, Kim SB, Martin AG, LoRusso PM, Ferrero JM, Badovinac-Crnjevic T, Hoersch S, Smitt M, Wildiers H. Trastuzumab emtansine versus treatment of physician's choice in patients with previously treated HER2-positive metastatic breast cancer (TH3RESA): final overall survival results from a randomised open-label phase 3 trial. The Lancet Oncology 2017, 18: 743-754. PMID: 28526538, DOI: 10.1016/s1470-2045(17)30313-3.Peer-Reviewed Original ResearchMeSH KeywordsAdo-Trastuzumab EmtansineAdultAgedAged, 80 and overAntibodies, Monoclonal, HumanizedAntineoplastic AgentsAntineoplastic Combined Chemotherapy ProtocolsBreast NeoplasmsBreast Neoplasms, MaleBridged-Ring CompoundsChemotherapy-Induced Febrile NeutropeniaDiarrheaEarly Termination of Clinical TrialsFemaleHemorrhageHumansLapatinibMaleMaytansineMiddle AgedNeoplasm MetastasisNeutropeniaPractice Patterns, Physicians'QuinazolinesReceptor, ErbB-2RetreatmentSurvival RateTaxoidsThrombocytopeniaTrastuzumabConceptsHER2-positive advanced breast cancerPhysician's choice groupAdvanced breast cancerWorse adverse eventsProgression-free survivalOverall survivalTrastuzumab emtansineAdverse eventsOverall survival analysisBreast cancerPhysician's choiceTH3RESA trialGrade 3Eastern Cooperative Oncology Group performance statusInvestigator-assessed progression-free survivalOpen-label phase 3 trialHER2-positive metastatic breast cancerSurvival analysisFinal overall survival analysisFinal overall survival resultsAdequate organ functionCommon grade 3Permuted block randomisationTrastuzumab emtansine treatmentSecond interim analysis
2016
Pictilisib for oestrogen receptor-positive, aromatase inhibitor-resistant, advanced or metastatic breast cancer (FERGI): a randomised, double-blind, placebo-controlled, phase 2 trial
Krop IE, Mayer IA, Ganju V, Dickler M, Johnston S, Morales S, Yardley DA, Melichar B, Forero-Torres A, Lee SC, de Boer R, Petrakova K, Vallentin S, Perez EA, Piccart M, Ellis M, Winer E, Gendreau S, Derynck M, Lackner M, Levy G, Qiu J, He J, Schmid P. Pictilisib for oestrogen receptor-positive, aromatase inhibitor-resistant, advanced or metastatic breast cancer (FERGI): a randomised, double-blind, placebo-controlled, phase 2 trial. The Lancet Oncology 2016, 17: 811-821. PMID: 27155741, PMCID: PMC5524539, DOI: 10.1016/s1470-2045(16)00106-6.Peer-Reviewed Original ResearchMeSH KeywordsAdultAgedAged, 80 and overBiomarkers, TumorBreast NeoplasmsDouble-Blind MethodDrug Resistance, NeoplasmEstradiolEstrogen Receptor AntagonistsFemaleFollow-Up StudiesFulvestrantHumansMiddle AgedNeoplasm Recurrence, LocalNeoplasm StagingPrognosisReceptor, ErbB-2Receptors, EstrogenSalvage TherapySurvival RateConceptsProgression-free survivalSerious adverse eventsTreatment-related serious adverse eventsWorse adverse eventsPlacebo groupAdverse eventsNon-measurable diseaseAromatase inhibitor treatmentPIK3CA mutationsBreast cancerDay 1Grade 3Inhibitor treatmentDay 15Cycle 1Median progression-free survivalHER2-negative breast cancerEndocrine-resistant breast cancerPIK3CA-mutated tumorsPhase 2 studyPhase 2 trialMetastatic breast cancerWeeks of treatmentAromatase inhibitor resistanceF Hoffmann-La Roche
2015
Adjuvant Paclitaxel and Trastuzumab for Node-Negative, HER2-Positive Breast Cancer
Tolaney SM, Barry WT, Dang CT, Yardley DA, Moy B, Marcom PK, Albain KS, Rugo HS, Ellis M, Shapira I, Wolff AC, Carey LA, Overmoyer BA, Partridge AH, Guo H, Hudis CA, Krop IE, Burstein HJ, Winer EP. Adjuvant Paclitaxel and Trastuzumab for Node-Negative, HER2-Positive Breast Cancer. New England Journal Of Medicine 2015, 372: 134-141. PMID: 25564897, PMCID: PMC4313867, DOI: 10.1056/nejmoa1406281.Peer-Reviewed Original ResearchMeSH KeywordsAdenocarcinomaAdultAgedAged, 80 and overAntibodies, Monoclonal, HumanizedAntineoplastic Combined Chemotherapy ProtocolsBreast NeoplasmsChemotherapy, AdjuvantDisease-Free SurvivalFemaleFollow-Up StudiesHumansInfusions, IntravenousMastectomy, SegmentalMiddle AgedNeoplasm Recurrence, LocalPaclitaxelRadiotherapyReceptor, ErbB-2Survival RateTrastuzumabConceptsHER2-positive breast cancerBreast cancerAdjuvant paclitaxelEjection fractionInvasive diseaseStage I HER2-positive breast cancerHuman epidermal growth factor receptor type 2Epidermal growth factor receptor type 2Symptomatic congestive heart failureHER2-negative breast cancerLeft ventricular ejection fractionDistant metastatic breast cancerFactor receptor type 2Discontinuation of trastuzumabGrade 3 neuropathySingle standard treatmentPrimary end pointCongestive heart failureMetastatic breast cancerVentricular ejection fractionPositive breast cancerInvestigator-initiated studyReceptor type 2Disease-specific eventsMedian follow
2013
Clinicopathological Features Among Patients With Advanced Human Epidermal Growth Factor–2-Positive Breast Cancer With Prolonged Clinical Benefit to First-Line Trastuzumab-Based Therapy: A Retrospective Cohort Study
Vaz-Luis I, Seah D, Olson EM, Wagle N, Metzger-Filho O, Sohl J, Litsas G, Burstein HJ, Krop IE, Winer EP, Lin NU. Clinicopathological Features Among Patients With Advanced Human Epidermal Growth Factor–2-Positive Breast Cancer With Prolonged Clinical Benefit to First-Line Trastuzumab-Based Therapy: A Retrospective Cohort Study. Clinical Breast Cancer 2013, 13: 254-263. PMID: 23829891, PMCID: PMC4084778, DOI: 10.1016/j.clbc.2013.02.010.Peer-Reviewed Original ResearchMeSH KeywordsAdultAgedAged, 80 and overAntineoplastic Agents, HormonalBreast NeoplasmsCarcinoma, Ductal, BreastCarcinoma, LobularChemotherapy, AdjuvantFemaleFollow-Up StudiesHumansMiddle AgedNeoplasm MetastasisNeoplasm Recurrence, LocalNeoplasm StagingPractice Patterns, Physicians'PrognosisReceptor, ErbB-2Receptors, EstrogenReceptors, ProgesteroneRetrospective StudiesSurvival RateTamoxifenYoung AdultConceptsTrastuzumab-based therapyFirst-line trastuzumab-based therapyAdvanced HER2-positive breast cancerHER2-positive breast cancerAdjuvant trastuzumabBreast cancerClinicopathological featuresClinical benefitC-statisticHuman epidermal growth factor-2-positive breast cancerTreatment durationPredictive valueHormone receptor-positive tumorsLong-term clinical benefitPrevious adjuvant trastuzumabTreatment duration groupsRetrospective cohort studyDisease-free intervalHormone receptor positivityReceptor-positive tumorsDuration of treatmentMagnitude of benefitLow predictive valueLogistic regression modelsDifferent logistic regression models
2012
Trastuzumab Emtansine for HER2-Positive Advanced Breast Cancer
Verma S, Miles D, Gianni L, Krop IE, Welslau M, Baselga J, Pegram M, Oh DY, Diéras V, Guardino E, Fang L, Lu MW, Olsen S, Blackwell K. Trastuzumab Emtansine for HER2-Positive Advanced Breast Cancer. New England Journal Of Medicine 2012, 367: 1783-1791. PMID: 23020162, PMCID: PMC5125250, DOI: 10.1056/nejmoa1209124.Peer-Reviewed Original ResearchMeSH KeywordsAdo-Trastuzumab EmtansineAdultAgedAged, 80 and overAntibodies, Monoclonal, HumanizedAntineoplastic AgentsAntineoplastic Combined Chemotherapy ProtocolsBreast NeoplasmsCapecitabineDeoxycytidineDisease-Free SurvivalFemaleFluorouracilHumansIntention to Treat AnalysisKaplan-Meier EstimateLapatinibMaytansineMiddle AgedNeoplasm MetastasisQuinazolinesReceptor, ErbB-2Survival RateTrastuzumabYoung AdultConceptsHER2-positive advanced breast cancerAdvanced breast cancerProgression-free survivalObjective response rateSecondary end pointsT-DM1Overall survivalBreast cancerEnd pointTrastuzumab emtansineInterim analysisResponse rateAdditional secondary end pointsMedian progression-free survivalHuman epidermal growth factor receptor 2Epidermal growth factor receptor 2Incidence of thrombocytopeniaMedian overall survivalPrimary end pointSerum aminotransferase levelsPalmar-plantar erythrodysesthesiaSecond interim analysisGrowth factor receptor 2Incidence of diarrheaFactor receptor 2