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BACKGROUND: Head and neck cancers (HNC) present diagnostic challenges due to multifocal disease manifestations, posing difficulties in distinguishing between metastatic disease and second primary malignancies (SPM). This complexity underscores the need for advanced diagnostic approaches. Emerging technologies, such as next-generation sequencing (NGS) and molecular classifier assays, show promise in providing precise insights into the diverse etiologies of HNC. METHOD: In this article, we employed NGS and molecular classifier assays to delve into three distinct clinical cases. The objective was to showcase the instrumental role of these technologies in facilitating accurate diagnoses and differentiating between metastatic disease and SPM in HNC cases. RESULTS: The results of this series highlight the effectiveness of NGS and molecular classifier assays in enhancing diagnostic accuracy for HNC and contributing to the precise differentiation of disease etiologies. The utilization of these advanced technologies proved instrumental in avoiding unnecessary interventions and paved the way for more targeted and effective treatment strategies. CONCLUSION: Our findings underscore the necessity of incorporating advanced molecular testing technologies into the diagnostic and therapeutic approaches for HNC, thereby championing a more nuanced and effective approach to managing these complex cases.
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The treatment for recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) with immune checkpoint inhibitors (anti-PD1) with or without chemotherapy has led to an improvement in survival. Yet, despite this therapeutic advancement, only 15%-19% of patients remain alive at four years, highlighting the poor survival and unmet need for improved therapies for this patient population. Some of the key evolving novel therapeutics beyond anti-PD1 in R/M HNSCC have included therapeutic vaccine therapies, bispecific antibodies/fusion proteins and multitargeted kinase inhibitors, and antibody-drug conjugates (ADCs). Multiple concurrent investigations of novel therapeutics for patients with R/M HNSCC beyond anti-PD(L)1 inhibition are currently underway with some promising early results. Beyond immune checkpoint inhibition, novel immunotherapeutic strategies including therapeutic vaccines ranging from targeting human papillomavirus-specific epitopes to personalized neoantigen vaccines are ongoing with some early efficacy signals and large, randomized trials. Other novel weapons including bispecific antibodies, fusion proteins, and multitargeted kinase inhibitors leverage multiple concurrent targets and modulation of the tumor microenvironment to harness antitumor immunity and inhibition of protumorigenic signaling pathways with emerging promising results. Finally, as with other solid tumors, ADCs remain a promising therapeutic intervention either alone or in combination with immunotherapy for patients with R/M HNSCC. With early enthusiasm across novel therapies in R/M HNSCC, results of larger randomized trials in R/M HNSCC are eagerly awaited.
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Inmunoterapia , Carcinoma de Células Escamosas de Cabeza y Cuello , Humanos , Carcinoma de Células Escamosas de Cabeza y Cuello/terapia , Carcinoma de Células Escamosas de Cabeza y Cuello/inmunología , Carcinoma de Células Escamosas de Cabeza y Cuello/tratamiento farmacológico , Inmunoterapia/métodos , Neoplasias de Cabeza y Cuello/terapia , Neoplasias de Cabeza y Cuello/inmunología , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Antígeno B7-H1/antagonistas & inhibidores , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Terapia Molecular Dirigida , Metástasis de la Neoplasia , Recurrencia Local de Neoplasia , Vacunas contra el Cáncer/uso terapéuticoRESUMEN
PURPOSE OF REVIEW: Extrapulmonary neuroendocrine carcinoma (EP-NEC) is a rare, aggressive malignancy that can arise from any organ and frequently presents with distant metastases. Advanced disease has a poor prognosis with median overall survival (OS) rarely exceeding 1 year even with systemic therapy. The management paradigm of advanced/metastatic EP-NEC has been extrapolated from small cell lung cancer (SCLC) and commonly consists of 1st line therapy with etoposide and platinum (cisplatin or carboplatin), followed by alternative cytotoxic regimens at the time of progression. Only a minority of patients are able to receive 2nd line therapy, and cytotoxics derived from the SCLC paradigm such as topotecan or lurbinectedin have very limited activity. We aimed to evaluate emerging therapeutic options in the 2nd and later lines and survey potential future developments in this space. RECENT FINDINGS: After a long period of stagnation in treatment options and outcomes, more promising regimens are gradually being utilized in the 2nd line setting including systemic therapy combinations such as FOLFIRI, FOLFOX, modified FOLFIRINOX, CAPTEM, and, more recently, novel checkpoint inhibitors such as nivolumab and ipilimumab. Simultaneously, advances in the understanding of disease biology are helping to refine patient selection and identify commonalities between NEC and their sites of origin which may eventually lead to additional targeted therapy options. While many questions remain, contemporary developments give grounds for optimism that improved outcomes for EP-NEC will soon be within reach.
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INTRODUCTION: Fanconi anemia (FA) is an inherited condition associated with genetic mutations that affect DNA repair proteins. More than 20 genes involved in the FA/BRCA pathway have been implicated in FA, including BRIP1 . Tumefactive brain lesions are rare in FA. CASE REPORT: We describe a patient with FA and recurrent tumefactive brain lesions preceded by calcifications on head computed tomography. A biopsy revealed white-matter gliosis with severe vasculopathy. Whole-genome sequencing demonstrated a BRIP1 homozygous variant with a final diagnosis of recurrent tumefactive brain lesions due to BRIP1 -associated CNS vasculopathy. Immunosuppressive treatment was ineffective in the present case. CONCLUSIONS: Mechanistically, the specific role of BRIP1 mutation in CNS inflammation and vasculopathy is unclear. However, immunodeficiency disorders can lead to autoimmunity and/or immune dysregulation due to the possible loss or gain of function of components of the immune system.
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Anemia de Fanconi , Humanos , Anemia de Fanconi/complicaciones , Anemia de Fanconi/genética , Anemia de Fanconi/patología , Mutación/genética , Sistema Nervioso Central/patologíaRESUMEN
Theranostics is the combination of two approaches-diagnostics and therapeutics-applied for decades in cancer imaging using radiopharmaceuticals or paired radiopharmaceuticals to image and selectively treat various cancers. The clinical use of theranostics has increased in recent years, with U.S. Food and Drug Administration (FDA) approval of lutetium 177 (177Lu) tetraazacyclododecane tetraacetic acid octreotate (DOTATATE) and 177Lu-prostate-specific membrane antigen vector-based radionuclide therapies. The field of theranostics has imminent potential for emerging clinical applications. This article reviews critical areas of active clinical advancement in theranostics, including forthcoming clinical trials advancing FDA-approved and emerging radiopharmaceuticals, approaches to dosimetry calculations, imaging of different radionuclide therapies, expanded indications for currently used theranostic agents to treat a broader array of cancers, and emerging ideas in the field. Keywords: Molecular Imaging, Molecular Imaging-Cancer, Molecular Imaging-Clinical Translation, Molecular Imaging-Target Development, PET/CT, SPECT/CT, Radionuclide Therapy, Dosimetry, Oncology, Radiobiology © RSNA, 2023.
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Neoplasias , Medicina de Precisión , Estados Unidos , Masculino , Humanos , Radiofármacos/uso terapéutico , Tomografía Computarizada por Tomografía de Emisión de Positrones , Radioisótopos/uso terapéutico , Neoplasias/diagnóstico por imagen , Neoplasias/terapiaRESUMEN
Poorly differentiated extrapulmonary neuroendocrine carcinomas (EP NECs) are aggressive cancers characterized by a high Ki-67 index, rapid tumor growth and poor survival, and are subdivided into small and large cell carcinoma. For small cell carcinoma of the lung, a pulmonary NEC, the combination of cytotoxic chemotherapy (CTX) and a checkpoint inhibitor (CPI) is considered standard therapy and superior to CTX alone. EP NECs are typically treated with platinum-based regimens, some clinicians have adopted the addition of a CPI to CTX based on data from trials in patients with small cell carcinoma of the lung. In this retrospective study of EP NECs, we report 38 patients treated with standard first-line CTX and 19 patients treated with CTX plus CPI. We did not observe any additional benefit of adding CPI to CTX in this cohort.
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Carcinoma Neuroendocrino , Carcinoma de Células Pequeñas , Tumores Neuroendocrinos , Humanos , Estudios Retrospectivos , Carcinoma Neuroendocrino/tratamiento farmacológico , Carcinoma Neuroendocrino/patología , Tumores Neuroendocrinos/tratamiento farmacológico , Tumores Neuroendocrinos/patologíaRESUMEN
Background: Patients with metastatic human papillomavirus-associated oropharyngeal cancer (HPV-OPC) have a median overall survival exceeding 2 years and are often candidates for multiple lines of palliative therapy. With the approval of immunotherapy as first-line treatment, salvage therapeutic options are limited. We describe our experience using capecitabine as salvage therapy for patients with recurrent or metastatic (R/M) HPV-OPC. Methods: We performed a retrospective study of patients with R/M HPV-OPC with distant metastatic disease. Eligible patients were identified from a medical oncology clinical database. Demographic and clinical data were abstracted from the medical record. Survival probabilities were estimated with the Kaplan-Meier method. Results: 10 patients were identified. Sites of metastatic disease included lung, liver, mediastinal lymph nodes, bone, abdominal lymph nodes, and soft tissue. Most patients received capecitabine as fourth-line treatment. The median duration from start of capecitabine therapy until death was 10.5 months. Best treatment response was as follows: partial responses (PR) were seen in 4 of 10 (40%), stable disease (SD) in 3 of 10 (30%), and progressive disease (PD) in 2 of 10 (20%). The clinical benefit rate (CR + PR + SD) was 70%. Reasons for discontinuation included disease progression (n = 8) and side effects (n = 2). One patient notably had prolonged benefit from capecitabine and continued to be on treatment for 34 months total. Conclusions: Capecitabine is a potential salvage treatment for heavily pretreated patients with R/M HPV-OPC, with some patients experiencing prolonged response. Clinical or molecular predictors of response would be helpful to identify patients likely to benefit; a larger prospective study would be useful to confirm efficacy in this patient population.
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The t(4;12)(q12;p13) has been rarely reported in both myeloid/lymphoid neoplasms with eosinophilia (ETV6/PDGFRA gene fusion) and acute myeloid leukemia (AML) (ETV6/CHIC2 gene fusion). The ability to accurately characterize t(4;12) is critical as myeloid neoplasms with PDGFRA rearrangements may be amenable to tyrosine kinase inhibitor (TKI) therapy. Herein, we describe a 60-year-old male with newly diagnosed AML and t(4;12)(q12;p13) by conventional chromosome studies. While the ETV6 break-apart fluorescence in situ hybridization (FISH) probe set demonstrated a balanced ETV6 gene rearrangement, the FIP1L1/CHIC2/PDGFRA tri-color and PDGFRA break-apart FISH probe sets could not resolve the ETV6 gene fusion partner. Mate-pair sequencing (MPseq), a next-generation sequencing assay, was subsequently performed and identified an ETV6 gene rearrangement (at 12p13) that involved an intergenic chromosomal region at 4q12, located between the CHIC2 and PDGFRA gene regions. Having excluded involvement by the PDGFRA gene region, the patient will not be considered for TKI therapy at any point during his medical management. The accurate characterization of structural rearrangements by NGS-based technologies, as demonstrated in this case, highlights the clinical relevance and potential impact on patient medical management of modern cytogenetic techniques.
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Cromosomas Humanos Par 12/genética , Cromosomas Humanos Par 4/genética , Leucemia Mieloide Aguda/genética , Proteínas de Fusión Oncogénica/genética , Análisis de Secuencia de ADN/métodos , Proteínas de Unión al ADN/genética , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Hibridación Fluorescente in Situ , Masculino , Persona de Mediana Edad , Proteínas Proto-Oncogénicas c-ets/genética , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas/genética , Proteínas Represoras/genética , Factores de Transcripción/genética , Translocación Genética , Proteína ETS de Variante de Translocación 6RESUMEN
BACKGROUND: Grade 3 gastroenteropancreatic neuroendocrine neoplasms (G3 GEPNENs) are often aggressive, and the optimal treatment is unclear for this subgroup of neuroendocrine neoplasms (NENs). Temozolomide (TEM)-based regimens have been increasingly used to treat grade 1-2 NENs, but their efficacy in G3 NENs remains undetermined. We aimed to assess the clinical efficacy of TEM-containing regimens in advanced grade 3 GEPNENs. MATERIALS AND METHODS: A multicenter retrospective review (2008-2018) of patients with metastatic/unresectable G3 GEPNENs who received a TEM-containing regimen was undertaken within a North American partnership to pool data. The primary endpoint was time to treatment failure (TTF). Radiologic response was extracted from local reports. RESULTS: One hundred and thirty patients in six high-volume NEN centers were included (median age 55, 64% male, 18% functional, 67% pancreatic NEN). Forty-nine percent were well-differentiated, 35% poorly differentiated, and 15% unknown based on local pathology reports. The regimen used was capecitabine and temozolomide (CAPTEM) in 92% and TEM alone in 8%. Radiological response by local assessment was seen in 36% of patients. Median TTF was 3.6 months and median overall survival (OS) 19.2 months. Six percent of patients required discontinuation of therapy due to adverse events. TTF was longer in first-line treatment (7.8 months vs. 2.9 months; hazard ratio, 1.62; 95% confidence interval, 1.11-2.36; p = .015) and in patients with pancreatic NENs (panNENs) compared with gastrointestinal NENs (5.8 months vs 1.8 months; p = .04). The overall response rate was higher in the first-line setting (51% vs 29%; p = .02) and in panNEN (41% vs 23%; p = .04). CONCLUSION: This is the largest TEM treatment series in G3 NEN, involving collaboration of several major North American NEN centers as a partnership. Thirty-six percent of patients showed some degree of radiographic response, and treatment was generally well tolerated, although the median duration of response was short. Response rates and time to treatment failure were superior in the first-line setting. CAPTEM should be considered a viable treatment option in this setting. Further randomized trials are warranted. IMPLICATIONS FOR PRACTICE: Neuroendocrine neoplasms (NENs) are heterogeneous, and optimal treatment for aggressive grade 3 (G3) NENs remains undetermined. The capecitabine and temozolomide (CAPTEM) regimen has been used in low-grade pancreas NENs but there are few data for its safety and efficacy in the G3 setting. This article reports on the efficacy of temozolomide-containing regimens, particularly CAPTEM, in management of G3 NENs. The good tolerance and response rate show that CAPTEM should be considered a viable regimen in treatment of G3 NENs pending confirmatory prospective studies.
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Neoplasias , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Estudios Retrospectivos , Temozolomida/uso terapéuticoRESUMEN
OBJECTIVES: Checkpoint inhibitors (CPIs) for low- and intermediate-grade neuroendocrine tumors (NETs) have been associated with limited efficacy; recent studies suggest CPIs may represent promising treatment for high-grade neuroendocrine neoplasms (NENs). METHODS: We examined 57 patients with NENs who were treated with CPIs to determine if NETs and neuroendocrine carcinomas (NECs) respond to immunotherapy. RESULTS: Patients with poorly differentiated NECs on CPI monotherapy had an objective response rate (ORR) of 0% and median progression-free survival (PFS) of 2.1 months (95% confidence interval [CI], 0.5-4.6). Patients with poorly differentiated NECs on dual CPI therapy had an ORR of 13% and PFS of 3.5 months (95% CI, 1.4-not reached [NR]). Patients with poorly differentiated NECs on CPI and cytotoxic therapy had an ORR of 36% with PFS of 4.2 months (95% CI, 1.6-NR). Well-differentiated grade 1 and 2 NETs on CPI monotherapy had an ORR of 25% with PFS NR. Well-differentiated grade 3 NETs had 0% ORR with a PFS of 2.9 months (95% CI, 1.4-4.2) on CPI monotherapy. CONCLUSIONS: Checkpoint inhibitor therapy shows limited activity in patients with NENs. Future studies should identify biomarkers that can help identify patients who are likely responders to immunotherapy.
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Hospitales , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Tumores Neuroendocrinos/tratamiento farmacológico , Neoplasias Pancreáticas/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Citotoxinas/administración & dosificación , Citotoxinas/efectos adversos , Femenino , Humanos , Inhibidores de Puntos de Control Inmunológico/administración & dosificación , Inhibidores de Puntos de Control Inmunológico/efectos adversos , Masculino , Persona de Mediana Edad , Clasificación del Tumor , Tumores Neuroendocrinos/patología , Neoplasias Pancreáticas/patología , Supervivencia sin Progresión , Tiroiditis/inducido químicamente , Resultado del Tratamiento , Adulto JovenRESUMEN
INTRODUCTION: Recent classification of neuroendocrine neoplasms has defined well-differentiated high-grade neuroendocrine tumors (NET G3) as a distinct entity from poorly differentiated neuroendocrine carcinoma. The optimal treatment for NET G3 has not been well-described. This study aimed to evaluate metastatic NET G3 response to different treatment regimens. MATERIALS AND METHODS: This was a retrospective study of patients with NET G3 within the Mayo Clinic database. Patients' demographics along with treatment characteristics, responses, and survival were assessed. Primary endpoints were progression-free survival (PFS) and overall survival. Secondary endpoints were objective response rate (ORR) and disease control rate (DCR). RESULTS: Treatment data was available in 30 patients with median age of 59.5 years at diagnosis. The primary tumor was mostly pancreatic (73.3%). Ki-67 index was ≥55% in 26.7% of cases. Treatments included capecitabine + temozolomide (CAPTEM) (n = 20), lutetium 177 DOTATATE (PRRT; n = 10), Platinum-etoposide (EP; n = 8), FOLFOX (n = 7), and everolimus (n = 2). CAPTEM exhibited ORR 35%, DCR 65%, and median PFS 9.4 months (95% confidence interval, 2.96-16.07). Both EP and FOLFOX showed similar radiographic response rates with ORR 25.0% and 28.6%; however, median PFS durations were quite distinct at 2.94 and 13.04 months, respectively. PRRT had ORR of 20%, DCR of 70%, and median PFS of 9.13 months. CONCLUSION: Among patients with NET G3, CAPTEM was the most commonly used treatment with clinically meaningful efficacy and disease control. FOLFOX or PRRT are other potentially active treatment options. EP has some activity in NET G3, but responses appear to be short-lived. Prospective studies evaluating different treatments effects in patients with NET G3 are needed to determine an optimal treatment strategy. IMPLICATIONS FOR PRACTICE: High-grade well-differentiated neuroendocrine tumors (NET G3) are considered a different entity from low-grade NET and neuroendocrine carcinoma in terms of prognosis and management. The oral combination of capecitabine and temozolomide is considered a good option in the management of metastatic NET G3 and may be preferred. FOLFOX is another systemic option with reasonable efficacy. Similar to other well-differentiated neuroendocrine tumors, peptide receptor radionuclide therapy seems to have some efficacy in these tumors.
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Tumores Neuroendocrinos , Capecitabina , Humanos , Persona de Mediana Edad , Tumores Neuroendocrinos/tratamiento farmacológico , Estudios Prospectivos , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
OBJECTIVES: A platinum/etoposide doublet is standard first-line therapy for poorly differentiated neuroendocrine carcinoma (PD NEC); however, evidence to guide treatment beyond first-line regimens is lacking. This study aimed to evaluate the efficacy of second-line regimens in PD NEC. METHODS: We performed a retrospective analysis of patients treated with second-line chemotherapy for PD NEC. Inclusion criteria were previous first-line therapy with platinum/etoposide, extrapulmonary PD NEC, and follow-up data. The primary end points were overall survival (OS) and progression-free survival (PFS) after second-line therapy. Secondary end points included OS and PFS from first-line therapy. RESULTS: Sixty-four patients were included. The median OS from initiation of second-line therapy was 6.2 months (95% confidence interval [CI], 4.9-8.9). The median PFS was 2.3 months (95% CI, 2.0-3.2). No second-line regimen showed a statistically significant difference in OS or PFS. There was a significant increase in OS for cisplatin first-line regimens compared with carboplatin (17.0 months [95% CI, 12.5-22.6] vs 11.7 months [95% CI, 8.0-14.0]). CONCLUSIONS: The efficacy of current second-line therapy in PD NEC is poor. No second-line regimen showed statistically significant superiority. Cisplatin was associated with longer OS regardless of second-line regimen or age. However, unmeasured confounders such as performance status or comorbidities may explain this effect.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma Neuroendocrino/tratamiento farmacológico , Neoplasias del Sistema Digestivo/tratamiento farmacológico , Terapia Recuperativa , Adulto , Anciano , Anciano de 80 o más Años , Carboplatino/administración & dosificación , Carcinoma Neuroendocrino/patología , Diferenciación Celular , Cisplatino/administración & dosificación , Neoplasias del Sistema Digestivo/patología , Femenino , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Neoplasias de Cabeza y Cuello/patología , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Supervivencia sin Progresión , Modelos de Riesgos Proporcionales , Estudios Retrospectivos , Resultado del Tratamiento , Neoplasias Urogenitales/tratamiento farmacológico , Neoplasias Urogenitales/patología , Adulto JovenRESUMEN
BACKGROUND: Primary neuroendocrine neoplasms (NENs) of the kidney are exceedingly rare malignancies and the available literature is very limited. The natural history and response to treatments is not well characterized. We aimed to describe the presenting features, demographics, tumor characteristics, and treatment outcomes of patients with renal NENs. PATIENTS AND METHODS: We performed a retrospective analysis of all Mayo Clinic patient records with a tissue diagnosis of a primary renal NEN. Baseline patient and surgical pathologic features and treatment modalities were collected. Time to recurrence after resection and overall survival (OS) were estimated using with survival analysis. Surveillance, Epidemiology, and End Results data were used to estimate the population-wide incidence and OS. RESULTS: A total of 17 patients were included in the present study, with a median follow-up of 62.8 months. Distant metastasis was present in 29% at diagnosis, with 76% experiencing distant metastasis at any point; 24% had a horseshoe kidney. Of the 17 patients, 14 had undergone surgical resection with no evidence of disease postoperatively. Ten of these patients had documented recurrence. The median time to recurrence was 18 months (95% confidence interval, 9-46 months). Only 1 of the 10 patients showed a radiographic response to systemic therapy. Of 9 patients, 4 had stable disease with somatostatin analogs. The median OS was 143 months (95% confidence interval, 50-143 months). CONCLUSIONS: Renal NENs are rare malignancies affecting mostly middle-age patients, with distant metastasis being common. Approximately one half of patients experience stable disease with somatostatin analogs. The OS usually exceeds 5 years.
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Neoplasias Renales/mortalidad , Recurrencia Local de Neoplasia/mortalidad , Tumores Neuroendocrinos/mortalidad , Adulto , Anciano , Anciano de 80 o más Años , Terapia Combinada , Femenino , Estudios de Seguimiento , Humanos , Neoplasias Renales/patología , Neoplasias Renales/terapia , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/patología , Recurrencia Local de Neoplasia/terapia , Tumores Neuroendocrinos/patología , Tumores Neuroendocrinos/terapia , Pronóstico , Estudios Retrospectivos , Tasa de Supervivencia , Adulto JovenRESUMEN
Opiate withdrawal/negative reinforcement has been implicated as one of the mechanisms for the progression from impulsive to compulsive drug use. Increase in the intracellular cAMP level and protein kinase A (PKA) activities within the neurocircuitry of addiction has been a leading hypothesis for opiate addiction. This increase requires the phosphorylation of µ-opioid receptor (MOR) at Tyr336 by Src after prolonged opiate treatment in vitro Here, we report that the Src-mediated MOR phosphorylation at Tyr336 is a prerequisite for opiate withdrawal in mice. We observed the recruitment of Src in the vicinity of MOR and an increase in phosphorylated Tyr336 (pY336) levels during naloxone-precipitated withdrawal. The intracerebroventricular or stereotaxic injection of a Src inhibitor (AZD0530), or Src shRNA viruses attenuated pY336 levels, and several somatic withdrawal signs. This was also observed in Fyn-/- mice. The stereotaxic injection of wild-type MOR, but not mutant (Y336F) MOR, lentiviruses into the locus coeruleus of MOR-/- mice restored somatic withdrawal jumping. Regulating pY336 levels during withdrawal might be a future target for drug development to prevent opiate addictive behaviors.