Abstract P3-14-12: Oncologic outcomes of immediate breast reconstruction after neoadjuvant chemotherapy in breast cancer patients: A matched case control study

Introduction: Although the indication for total mastectomy (TM) with immediate breast reconstruction (IBR) has been expanded, IBR after neoadjuvant chemotherapy (NACT) is still controversy. We assumed that TM with IBR after NACT is feasible surgical treatment in breast cancer patients. Methods: A retrospective review of breast cancer patients who underwent TM with IBR after NACT between 2008 and 2015 at a single center was conducted. These cases were matched by 1:5 to patients who underwent mastectomy alone after NACT. Matching variables included age, clinical T and N staging before NACT, response to NACT, and pathologic staging after NACT. Pathological stage was followed by seventh American Joint Committee on Cancer (AJCC) classification. Results: Overall, 31 patients were identified in the TM with IBR group (Study group) and 85 patients (Control group) were matched. In the study group, 13 (41.9%) patients underwent nipple-sparing mastectomy (NSM) and 18 (58.1%) underwent skin-sparing mastectomy (SSM). Median follow-up duration was 29.2 (7-31) and 38.8 (11-85) months for the study and control group, respectively. Median age was 37.0 (26-57) and 40.0 (24-56) years for the study and control group, respectively. The clinicopathologic characteristics of both groups are summarized in Table1. Disease-free survival (p=0.520), local recurrence-free survival (p=0.610), distant metastasis-free survival (p=0.795), and over survival (p=0.971) did not differ significantly between two groups. Conclusion: TM with IBR after NACT is feasible surgical treatment option in breast cancer patients.

Clinicopathologic characteristicsVariablesControl group (n=85)Study group (n=31)p-valueAge, years (matching variables)  0.890≤3515 (17.7)9 (29.0) 36-5061 (71.8)21 (67.7) 51≥9 (10.6)1 (3.2) BMI, m2/kg  0.13025≤62 (72.9)28 (90.3) 26-3018 (21.2)2 (6.5) 30>5 (5.9)1 (3.2) Histology  0.326Ductal carcinoma in situ2 (2.4)3 (9.7) Invasive ductal carcinoma74 (87.1)28 (90.3) Invasive lobular carcinoma2 (2.4)0 (0) Others7 (8.2)0 (0) Multiplicity  0.063yes19 (22.6)12 (40.0) no65 (77.4)18 (60.0) Lymphovascular invasion  0.161yes33 (39.3)17 (54.8) no51 (60.7)14 (45.2) Nuclear grade  0.317Low10 (11.9)1 (3.3) Intermediate27 (32.1)14 (46.7) High47 (56.0)15 (24.2) Pathologic T stage (matching variable)  0.154T17 (8.2)6 (19.4) T229 (34.1)15 (48.4) T331 (36.5)4 (12.9) T418 (21.2)6 (19.4) Pathologic N stage (matching variable)  0.494N036 (42.4)13 (41.9) N123 (27.1)13 (41.9) N216 (18.8)4 (12.9) N310 (11.8)1 (3.2) Estrogen receptor  0.608positive49 (57.7)15 (48.4) negative36 (42.4)16 (51.6) Progesterone receptor  0.291positive40 (47.1)10 (32.3) negative45 (52.9)21 (67.7) HER2 status  0.345amplification29 (34.1)10 (32.3) not amplification56 (65.9)21 (67.7) Clinical T-stage (matching variable)  0.897cT12 (2.4)1 (3.2) cT231 (36.5)12 (38.7) cT346 (54.1)16 (51.6) cT46 (7.1)2 (6.5) Clinical N stage (matching variable)  0.947cN03 (3.5)1 (3.2) cN120 (23.5)10 (32.3) cN236 (42.4)10 (32.3) cN326 (30.6)10 (32.3) Response (matching variable)  1.000Partial response64 (75.3)27 (29.7) Stable disease21 (24.7)4 (12.9) 

Citation Format: Ryu JM, Lee JE, Kim SW, Yu J, Rayzah M, Lee SK, Mansoor A, Bae SY, Park S, Paik H-J, Kim I, Bang SI, Jeon BJ, Mun G-H, Pyon J-K. Oncologic outcomes of immediate breast reconstruction after neoadjuvant chemotherapy in breast cancer patients: A matched case control study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-14-12.

IK acts as an immunoregulator of inflammatory arthritis by suppressing TH17 cell differentiation and macrophage activation

Pathogenic T helper cells (TH) and macrophages have been implicated in the development of rheumatoid arthritis (RA), which can lead to severe synovial inflammation and bone destruction. A range of therapies have been widely used for RA, including specific monoclonal antibodies and chemical inhibitors against inflammatory cytokines produced by these cells. However, these have not been sufficient to meet the medical need. Here, we show that in transgenic mice expressing truncated IK (tIK) cytokine, inflammatory arthritis symptoms were ameliorated as the result of suppression of the differentiation of TH1 and TH17 cells and of macrophage activation. During inflammatory responses, tIK cytokine systemically regulated macrophage functions and TH17 cell differentiation through inactivation of the MAPK and NF-κB pathways. Interestingly, the level of tIK cytokine was higher in synovial fluid of RA patients compared with that in osteoarthritis (OA) patients. Our observations suggest that tIK cytokine can counterbalance the induction of inflammatory cells related to RA and thus could be a new therapeutic agent for the treatment of RA.

Predictors of general discomfort, limitations in activities of daily living and intention of a second donation in unrelated hematopoietic stem cell donation

We performed a retrospective study of 1868 consecutive unrelated donors to predict the risk factors related to general discomfort, limitations in activities of daily living (ADLs) and intention of a second donation in hematopoietic stem cell (HSC) donation. General discomfort and limitations in ADLs were assessed by numerical measurement (scores of 0-10) and donor's intention of a second donation by yes or no reply. The post-donation questionnaires were completed within 48 h after HSC collection and at 1 week, 4 weeks, and 4 months thereafter. Predictors of general discomfort included female sex (P<0.0001), bone marrow (BM) collection (P<0.0001) or PBSC collection through a central line (CL; P=0.0349), 2-day collection (P=0.0150) and negative or undetermined intention of a second donation on day 1 (P<0.0001). Predictors of limitations in ADLs included age group of 30-39 years (P=0.0046), female sex (P<0.0001), BM collection (P<0.0001) or PBSC collection through a CL (P<0.0001) and negative or undetermined intention of a second donation on day 1 (P<0.0001). The only predictor of positive intention of a second donation was male sex (P=0.0007). Age, sex and collection method and period should be considered risk factors when unrelated HSC donation is performed.

Nanophotonic modal dichroism: mode-multiplexed modulators

As the diffraction limit is approached, device miniaturization to integrate more functionality per area becomes more and more challenging. Here we propose a strategy to increase the functionality-per-area by exploiting the modal properties of a waveguide system. With such an approach the design of a mode-multiplexed nanophotonic modulator relying on the mode-selective absorption of a patterned indium-tin-oxide (ITO) is proposed. Full-wave simulations of a device operating at the telecom wavelength of 1550 nm show that two modes can be independently modulated, while maintaining performances in line with conventional single-mode ITO modulators reported in the recent literature. The proposed design principles can pave the way to a class of mode-multiplexed compact photonic devices able to effectively multiply the functionality-per-area in integrated photonic systems.

Tuning the ferromagnetic phase in the CDW compound SmNiC2 via chemical alloying

We report a study on tuning the charge density wave (CDW) ferromagnet SmNiC2 to a weakly coupled superconductor by substituting La for Sm. X-ray diffraction measurements show that the doped compounds obey Vegard's law, where La (Lu) alloying expands (shrinks) the lattice due to its larger (smaller) atomic size than Sm. In the series Sm1-xLaxNiC2, CDW transition (TCDW = 148 K) for SmNiC2 is gradually suppressed, while the ferromagnetic (FM) ordering temperature (TC) at 17 K slightly increases up to x = 0.3. For x > 0.3, TC starts to decrease and there is no signature that could be related with the CDW phase. Electrical resistivity, magnetic susceptibility and specific heat measurements point toward the possible presence of a FM quantum critical point (QCP) near x = 0.92, where the TC is extrapolated to zero temperature. Superconductivity in LaNiC2 (Tsc = 2.9 K) is completely suppressed with small amount of Sm inclusion near the proposed FM critical point, indicating a competition between the two ordered phases. The tunable lattice parameters via chemical substitution (La,Lu) and the ensuing change among the ordered phases of ferromagnetism, CDW and superconductivity underscores that SmNiC2 provides a rich avenue to study the rare example of a FM QCP, where the broken symmetries are intricately correlated.

Liver Transplantation in a Patient With CD40 Ligand Deficiency and Hyper-IgM Syndrome: Clinical and Immunological Assessments

Monoclonal antibodies that disrupt CD40-CD40 ligand (CD40L) interactions are likely to have use in human transplantation. However, the extent of the immunosuppressive effects of CD40-CD40L blockade in humans is unknown. Hyper-IgM syndrome (HIGM) is a rare primary immunodeficiency syndrome characterized by defects in the CD40-CD40L pathway, severe immune deficiency (IgG), and high or normal IgM levels. However, the effects of CD40L deficiency on T- and natural killer (NK)-cell function is not established. Here, we present a patient with HIGM syndrome who underwent liver transplantation for hepatitis C virus infection. Posttransplantation, NK-cell antibody-dependent cytokine release (γ-interferon) to alloantigens and T cell responses to viral antigens and mitogens were assessed and showed normal CD4⁺ , CD8⁺ , and NK-cell responses. We also examined antibody-dependent cellular cytotoxicity against a CD40⁺ and HLA-expressing cell line. These experiments confirmed that the patient's NK cells were equivalent to those of normal subjects in mediating antibody-dependent cellular cytotoxicity despite the absence of CD40-CD40L interactions. Mitogenic stimulation of the patient's peripheral blood mononuclear cells showed no expression of CD40L on T and NK cells compared with increased expression in normal subjects. Taken together, these data suggest that absence of CD40L expression is responsible for aberrant B cell immunity but had little impact on NK- and T cell immune responses in vitro.

Bay 61-3606 Sensitizes TRAIL-Induced Apoptosis by Downregulating Mcl-1 in Breast Cancer Cells

Breast cancer cells generally develop resistance to TNF-Related Apoptosis-Inducing Ligand (TRAIL) and, therefore, assistance from sensitizers is required. In our study, we have demonstrated that Spleen tyrosine kinase (Syk) inhibitor Bay 61–3606 was identified as a TRAIL sensitizer. Amplification of TRAIL-induced apoptosis by Bay 61–3606 was accompanied by the strong activation of Bak, caspases, and DNA fragmentation. In mechanism of action, Bay 61–3606 sensitized cells to TRAIL via two mechanisms regulating myeloid cell leukemia sequence-1 (Mcl-1). First, Bay 61–3606 triggered ubiquitin-dependent degradation of Mcl-1 by regulating Mcl-1 phosphorylation. Second, Bay 61–3606 downregulates Mcl-1 expression at the transcription level. In this context, Bay 61–3606 acted as an inhibitor of Cyclin-Dependent Kinase (CDK) 9 rather than Syk. In summary, Bay 61–3606 downregulates Mcl-1 expression in breast cancer cells and sensitizes cancer cells to TRAIL-mediated apoptosis.

Incidence and risk factors of deep vein thrombosis after liver transplantation

BACKGROUND

Deep venous thrombosis (DVT) occurs in 0.1% of persons per year, affecting 15%-40% of general surgical procedures without prophylaxis. Thromboembolic prophylaxis is not commonly used after orthotopic liver transplantation (LT) owing to the risks of bleeding and coagulopathy. Cirrhosis and the association with the coagulation cascade, before and after transplantation, are not well understood. The purpose of this study was to determine the incidence of DVT and its risk factors after LT.

METHODS

We retrospectively reviewed LTs performed at our center from 2005 to 2012. We identified patients with Doppler examinations showing DVT after LT, platelet count, and international normalized ratio (INR) at time of DVT, associated symptoms, DVT prophylaxis, and perioperative risk factors. We determined the incidence of DVT, the odds ratio of each preoperative risk factor, the difference in platelet count and INR between those with and without a DVT, and the weighted risk of each factor in the development of DVT with the use of logistic regression modeling.

RESULTS

Of 314 patients, the incidence of DVT was 8.6% (27/314). Between those with and without DVT there was no significant difference in age, sex, platelet count, INR, infection, hepatocellular cancer, use of venous bypass, and prior surgery. There was a significant difference in mobility, 67% vs 20% (P < .0001), and the use of factor VII, 11% vs 2% (P < .05). The estimated risk for of developing DVT for patients with neither of these factors was 4%; with factor VII the risk rose to 17%; with mobility difficulty the risk rose to 23%; and with both the risk was 62%. In our entire population, there were no cases of pulmonary embolism.

CONCLUSIONS

The risk of developing a DVT after LT is ≥9% even with mechanical DVT prophylaxis. Consideration should be given to using both mechanical and chemical prophylaxis after LT.

Correspondence of physical activity and fruit/vegetable consumption among prostate cancer survivors and their spouses

A healthy diet and physical activity are recommended for prostate cancer survivors. Interdependence theory suggests that the spousal relationship influences those health behaviours and the degree of correspondence may be an indicator of this influence. This study evaluated the correspondence between prostate cancer survivors and spouses regarding physical activity and fruit/vegetable consumption. Baseline data from an ongoing randomised control trial were utilised. Men who had been treated for prostate cancer within the past year and their partners (N = 132 couples) completed self-report measures of physical activity, fruit/vegetable consumption, relationship satisfaction and support for partner's healthy diet and physical activity. Couples reported similar fruit/vegetable consumption and physical activity as indicated by high levels of correspondence. Greater fruit/vegetable correspondence was related to higher relationship satisfaction (F = 4.14, P = 0.018) and greater patient (F = 13.29, P < 0.001) and spouse-rated support (F = 7.2, P < 0.001). Greater physical activity correspondence was related to greater patient (F = 3.57, P = 0.028) and spouse-rated support (F = 4.59, P = 0.031). Prostate cancer survivors and spouses may influence each other's diet and exercise behaviours. Couple-based interventions may promote healthy behaviours among this population.

Disparate roles of zinc in chemical hypoxia-induced neuronal death

Accumulating evidence has provided a causative role of zinc (Zn²⁺) in neuronal death following ischemic brain injury. Using a hypoxia model of primary cultured cortical neurons with hypoxia-inducing chemicals, cobalt chloride (1 mM CoCl₂), deferoxamine (3 mM DFX), and sodium azide (2 mM NaN₃), we evaluated whether Zn²⁺ is involved in hypoxic neuronal death. The hypoxic chemicals rapidly elicited intracellular Zn²⁺ release/accumulation in viable neurons. The immediate addition of the Zn²⁺ chelator, CaEDTA or N,N,N’N’-tetrakis-(2-pyridylmethyl) ethylenediamine (TPEN), prevented the intracellular Zn²⁺ load and CoCl₂-induced neuronal death, but neither 3 hour later Zn²⁺ chelation nor a non-Zn²⁺ chelator ZnEDTA (1 mM) demonstrated any effects. However, neither CaEDTA nor TPEN rescued neurons from cell death following DFX- or NaN₃-induced hypoxia, whereas ZnEDTA rendered them resistant to the hypoxic injury. Instead, the immediate supplementation of Zn²⁺ rescued DFX- and NaN₃-induced neuronal death. The iron supplementation also afforded neuroprotection against DFX-induced hypoxic injury. Thus, although intracellular Zn²⁺ release/accumulation is common during chemical hypoxia, Zn²⁺ might differently influence the subsequent fate of neurons; it appears to play a neurotoxic or neuroprotective role depending on the hypoxic chemical used. These results also suggest that different hypoxic chemicals may induce neuronal death via distinct mechanisms.

Depletion of the cereblon gene activates the unfolded protein response and protects cells from ER stress-induced cell death

Previous studies showed that cereblon (CRBN) binds to various cellular target proteins, implying that CRBN regulates a wide range of cell responses. In this study, we found that deletion of the Crbn gene desensitized mouse embryonic fibroblast cells to various cell death-promoting stimuli, including endoplasmic reticulum stress inducers. Mechanistically, deletion of Crbn activates pathways involved in the unfolded protein response prior to ER stress induction. Loss of Crbn activated PKR-like ER kinase (PERK) with enhanced phosphorylation of eIF2α. Following ER stress induction, loss of Crbn delayed dephosphorylation of eIF2α, while reconstitution of Crbn reversed enhanced phosphorylation of PERK and eIF2α. Lastly, we found that activation of the PERK/eIF2α pathway following Crbn deletion is caused by activation of AMP-activated protein kinase (AMPK). We propose that CRBN plays a role in cellular stress signaling, including the unfolded protein response, by controlling the activity of AMPK.

Detection of Peripheral Arterial Disease Within the Foot Using Vascular Optical Tomographic Imaging: A Clinical Pilot Study

OBJECTIVE

Vascular optical tomographic imaging (VOTI) is a novel imaging modality that is capable of detecting hemoglobin concentrations in tissue. VOTI is non-invasive, non-ionizing and does not require contrast injection. This technology was applied to the diagnosis of peripheral arterial disease (PAD) within lower extremities of diabetic patients with calcified arteries. This could be of substantial benefit as these patients suffer from comorbidities such as arterial incompressibility, which complicates diagnosis and monitoring.

METHODS

Forty individuals (10 non-diabetic patients with PAD, 10 diabetic patients with PAD, and 20 healthy volunteers) were enrolled in a diagnostic pilot study using the VOTI system. The patients were imaged during at high pressure cuff occlusion.

RESULTS

The VOTI system was capable of quantifying the blood volume changes within the foot during the thigh cuff occlusion and outputting diagnostic parameters, such as change in hemoglobin concentration, enabling the assessment of foot perfusion. This study resulted in a statistically significant difference between the healthy cohort and both the non-diabetic and the diabetic PAD cohorts (p = .006, p = .006). Receiver operating characteristic (ROC) curve analysis showed that PAD diagnosis could be made with over 80% sensitivity or specificity depending on the characteristic cutoff point. In addition, VOTI was capable of providing the locations of under-perfused regions within the foot and evaluating the severity of arterial disease, even within diabetic patients with calcified arteries, who are traditionally difficult to diagnose.

CONCLUSION

VOTI can effectively diagnose PAD independently of arterial compressibility, making it very useful for assessing vascular disease in diabetic patients.

Temperature dependence of the radiative recombination time in ZnO nanorods under an external magnetic field of 6 T

The Temperature dependence of the exciton radiative decay time in ZnO nanorods has been investigated, which is associated with the density of states for the intra-relaxation of thermally excited excitons. The photoluminescence decay time was calibrated by using the photoluminescence intensity in order to obtain the radiative decay time. In the absence of an external magnetic field, we have confirmed that the radiative decay time increased with temperature in a similar manner to that seen in bulk material (∼ T1.5). Under an external magnetic field of 6 T parallel to the c-axis, we found that the power coefficient of the radiative decay time with temperature decreased (∼ T1.3) when compared to that in the absence of a magnetic field. This result can be attributed to an enhancement of the effective mass perpendicular to the magnetic field and a redshift of the center-of-mass exciton as a consequence of perturbation effects in the weak-field regime.

Incidence of venous thromboembolism following major surgery in Korea: from the Health Insurance Review and Assessment Service database

BACKGROUND

Data on the incidence of venous thromboembolism (VTE) following major surgery in Asian populations are limited.

METHODS

Using the Korean Health Insurance Review and Assessment Service database, we performed a nationwide population-based epidemiologic study to estimate the incidence of VTE after major orthopedic, cancer, and benign surgeries. VTE cases were identified from all patients undergoing major surgery between 2007 and 2011 using both diagnostic and drug codes as treatment evidence of VTE within 5 weeks of surgery. We also calculated the relative risk of VTE in major orthopedic and cancer surgery compared to benign surgery.

RESULTS

The overall rates of postoperative VTE were 1.24%, 0.67%, and 0.05% for major orthopedic, cancer, and benign surgeries, respectively. Hip fracture (1.60%) and colorectal cancer surgeries (1.67%) were associated with the highest rates of VTE, and the rates steadily increased during the study period. Advanced age, female sex, and general anesthesia were independent risk factors for VTE. Patients undergoing surgery for colorectal, pancreatic, ovarian, and esophageal cancer, and major orthopedic surgery had a > 20-fold higher risk of VTE than those undergoing benign surgery.

CONCLUSIONS

This is the largest epidemiologic study to investigate the incidence of VTE after major surgery in Asia, demonstrating that the rates of postoperative VTE are lower than in Caucasian populations. This study contributes to a better understanding of the differences in postoperative VTE development between Korean and Caucasian populations; the data also suggest that perioperative prophylactic strategies in Asians should be based on studies of such populations.

CGP74514A enhances TRAIL-induced apoptosis in breast cancer cells by reducing X-linked inhibitor of apoptosis protein

BACKGROUND

Despite the selectivity of Tumor necrosis factor Related Apoptosis-Inducing Ligand (TRAIL) for cancer cell killing activity, breast cancer cells are resistant to TRAIL-induced apoptosis for various reasons.

MATERIALS AND METHODS

From a functionally-characterized small-molecule dataset, CGP74514A was identified as a TRAIL sensitizer in MCF-7 breast cancer cells. Combination of sub-toxic dose of TRAIL with CGP74514A was evaluated in three TRAIL-resistant breast cancer cells, MCF-7, T47D and SK-BR-3.

RESULTS

In all tested cells, CGP74514A enhanced TRAIL sensitivity. Combination treatment triggered apoptotic events faster than single treatment. Regarding its mechanism of action, CGP74514A reduced cytosolic X-linked inhibitor of apoptosis protein (XIAP). Small interfering RNA-mediated knockdown experiments showed that reduction of XIAP is the reason of sensitization.

CONCLUSION

CGP74514A sensitized breast cancer cells to TRAIL via reduction of XIAP expression level.

Spontaneous resolution of post-transplant localized cytomegalovirus lymphadenitis mimicking tumor recurrence

Compromised T-cell immunity persists for up to 1 year after autologous stem cell transplantation (ASCT), and patients treated with ASCT are more likely to develop atypical lymphoid hyperplasia that mimics tumor recurrence. Here, we present a case of cervical lymphadenitis due to cytomegalovirus (CMV) reactivation in a patient who had undergone ASCT for Burkitt lymphoma, which mimicked tumor recurrence on computed tomography and positron emission tomography-computed tomography 6 months after ASCT. This lesion was confined to the regional lymph nodes and was not accompanied by signs of systemic involvement, such as fever, splenomegaly, an elevated C-reactive protein level, or viremia. The localized CMV lymphadenitis resolved spontaneously without treatment after 6 months (12 months after ASCT) and the elevated CMV immunoglobulin-M titer normalized 6 months after resolution. Our experience with this case suggests that cautious follow-up without anti-CMV treatment should be considered in cases of post-ASCT localized CMV lymphadenitis without systemic involvement in patients with complete engraftment.

Ribosomal protein L19 overexpression activates the unfolded protein response and sensitizes MCF7 breast cancer cells to endoplasmic reticulum stress-induced cell death

Although first identified for their roles in protein synthesis, certain ribosomal proteins exert pleiotropic physiological functions in the cell. Ribosomal protein L19 is overexpressed in breast cancer cells by amplification and copy number variation. In this study, we examined the novel pro-apoptotic role of ribosomal protein L19 in the breast cancer cell line MCF7. Overexpression of RPL19 sensitized MCF7 cells to endoplasmic reticulum stress-induced cell death. RPL19 overexpression itself was not cytotoxic; however, cell death induction was enhanced when RPL19 overexpressing cells were incubated with endoplasmic reticulum stress-inducing agents, and this sensitizing effect was specific to MCF7 cells. Examination of the cell signaling pathways that mediate the unfolded protein response (UPR) revealed that overexpression of RPL19 induced pre-activation of the UPR, including phosphorylation of pERK-like ER kinase (PERK), phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α), and activation of p38 MAPK-associated stress signaling. Our findings suggest that upregulation of RPL19 induces ER stress, resulting in increased sensitivity to ER stress and enhanced cell death in MCF7 breast cancer cells.

Pre-clinical characterization of Dacomitinib (PF-00299804), an irreversible pan-ErbB inhibitor, combined with ionizing radiation for head and neck squamous cell carcinoma

Epidermal growth factor receptor (EGFR) is over-expressed in nearly all cases of squamous cell carcinoma of the head and neck (SCCHN), and is an important driver of disease progression. EGFR targeted therapies have demonstrated clinical benefit for SCCHN treatment. In this report, we investigated the pre-clinical efficacy of Dacomitinib (PF-00299804), an irreversible pan-ErbB inhibitor, both alone and in combination with ionizing radiation (IR), a primary curative modality for SCCHN. One normal oral epithelial (NOE) and three SCCHN (FaDu, UT-SCC-8, UT-SCC-42a) cell lines were used to conduct cell viability, clonogenic survival, cell cycle, and immunoblotting assays in vitro, using increasing doses of Dacomitinib (10–500 nM), both with and without IR (2–4 Gy). The FaDu xenograft model was utilized for tumor growth delay assays in vivo, and immunohistochemical analyses were conducted on extracted tumors. A dose-dependent reduction in cell viability and clonogenic survival after Dacomitinib treatment was observed in all three SCCHN models. Treatment led to a significant reduction in EGFR signalling, with a subsequent decrease in phosphorylation of downstream targets such as ERK, AKT, and mTOR. In vivo, Dacomitinib treatment delayed tumor growth, while decreasing phospho-EGFR and Ki-67 immunoexpression. These effects were further enhanced when combined with IR, both in vitro and in vivo. The preclinical data support the further evaluations of Dacomitinib combined with IR for the future management of patients with SCCHN.