Daniel J. Ma

Conditional probability of long-term survival in glioblastoma: a population-based analysis.

Advances in glioblastoma care have resulted in a larger proportion of patients surviving beyond 2 years after diagnosis. It is not clear how long‐term survivors should be counseled with respect to future prognosis, or what factors influence that prognosis. The conditional probability of survival was evaluated from multiple time points in patients with glioblastoma, using Surveillance, Epidemiology, and End Results (SEER) data.

MARQUIS: A multiplex method for absolute quantification of peptides and posttranslational modifications

Absolute quantification of protein expression and post-translational modifications by mass spectrometry has been challenging due to a variety of factors, including the potentially large dynamic range of phosphorylation response. To address these issues, we have developed MARQUIS — Multiplex Absolute Regressed Quantification with Internal Standards — a novel mass spectrometry-based approach using a combination of isobaric tags and heavy-labeled standard peptides to construct internal standard curves for peptides derived from key nodes in signal transduction networks. We applied MARQUIS to quantify phosphorylation dynamics within the EGFR network at multiple time points following stimulation with several ligands, enabling a quantitative comparison of EGFR phosphorylation sites and demonstrating that receptor phosphorylation is qualitatively similar but quantitatively distinct for each EGFR ligand tested. MARQUIS was also applied to quantify the effect of EGFR kinase inhibition on glioblastoma patient derived xenografts. MARQUIS is a versatile method, broadly applicable and extendable to multiple mass spectrometric platforms.

Factors Influencing the Central Nervous System Distribution of a Novel Phosphoinositide 3-Kinase/Mammalian Target of Rapamycin Inhibitor GSK2126458: Implications for Overcoming Resistance with Combination Therapy for Melanoma Brain Metastases.

Small molecule inhibitors targeting the mitogen-activated protein kinase pathway (Braf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase) have had success in extending survival for patients with metastatic melanoma. Unfortunately, resistance may occur via cross-activation of alternate signaling pathways. One approach to overcome resistance is to simultaneously target the phosphoinositide 3-kinase/mammalian target of rapamycin signaling pathway. Recent reports have shown that GSK2126458 [2,4-difluoro-N-(2-methoxy-5-(4-(pyridazin-4-yl)quinolin-6-yl)pyridin-3-yl) benzenesulfonamide], a dual phosphoinositide 3-kinase/mammalian target of rapamycin inhibitor, can overcome acquired resistance to Braf and mitogen-activated protein kinase kinase inhibitors in vitro. These resistance mechanisms may be especially important in melanoma brain metastases because of limited drug delivery across the blood–brain barrier. The purpose of this study was to investigate factors that influence the brain distribution of GSK2126458 and to examine the efficacy of GSK2126458 in a novel patient-derived melanoma xenograft (PDX) model. Both in vitro and in vivo studies indicate that GSK2126458 is a substrate for P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp), two dominant active efflux transporters in the blood–brain barrier. The steady-state brain distribution of GSK2126458 was 8-fold higher in the P-gp/Bcrp knockout mice compared with the wild type. We also observed that when simultaneously infused to steady state, GSK212658, dabrafenib, and trametinib, a rational combination to overcome mitogen-activated protein kinase inhibitor resistance, all had limited brain distribution. Coadministration of elacridar, a P-gp/Bcrp inhibitor, increased the brain distribution of GSK2126458 by approximately 7-fold in wild-type mice. In the PDX model, GSK2126458 showed efficacy in flank tumors but was ineffective in intracranial melanoma. These results show that P-gp and Bcrp are involved in limiting the brain distribution of GSK2126458 and provide a rationale for the lack of efficacy of GSK2126458 in the orthotopic PDX model.

Risk factors for locoregional relapse after transoral robotic surgery for human papillomavirus–related oropharyngeal squamous cell carcinoma

Factors predicting locoregional relapse after surgery for oropharyngeal squamous cell carcinoma (SCC) were identified in the pre‐human papillomavirus (HPV) era. We examined whether traditional indications for adjuvant radiotherapy (RT) or adjuvant chemoradiotherapy (CRT) still correlate with locoregional relapse in HPV‐positive patients after transoral robotic surgery (TORS).

Safety and Tolerability of SBRT after High-Dose External Beam Radiation to the Lung.

Purpose: Stereotactic body radiotherapy (SBRT) is commonly used to treat unresectable lung nodules. Given its relative safety and effective local control, SBRT has also been used to treat recurrent lung nodules after high-dose external beam radiation (EBRT) to the lung. The toxicity of such treatment is unknown. Methods and Materials: Between 2006 and 2012, 18 subjects at the Mayo Clinic with 27 recurrent lung nodules were treated with SBRT after receiving EBRT to the lung. Median local control, overall survival, and progression-free survival (PFS) were described. Acute toxicity and late toxicity (defined as toxicity ≥ and >90 days, respectively) were reported and graded as per standardized CTCAE 4.0 criteria. Results: The median age of patients treated was 68 years. Fifteen patients had recurrent lung cancer as their primary histology. Twelve patients received ≥60 Gy of conventional EBRT prior to SBRT. SBRT dose and fractionation varied; the most common prescriptions were 48 Gy/4, 54 Gy/3, and 50 Gy/5 fractions. Only four patients had SBRT planning target volumes (PTVs) that overlapped more than 50% of their prior EBRT PTV. Two patients developed local recurrence following SBRT. With a median follow up of 21.2 months, median SBRT-specific overall survival and PFS were 21.7 and 12.3 months, respectively. No grade ≥3 acute or late toxicities were noted. Conclusion: Stereotactic body radiotherapy may be a good salvage option for select patients with recurrent lung nodules following definitive EBRT to the chest. Toxicity is minimal and local control is excellent.

Heterogeneous binding and central nervous system distribution of the multitargeted kinase inhibitor ponatinib restrict orthotopic efficacy in a patient-derived xenograft model of glioblastoma

This study investigated how differences in drug distribution and free fraction at different tumor and tissue sites influence the efficacy of the multikinase inhibitor ponatinib in a patient-derived xenograft model of glioblastoma (GBM). Efficacy studies in GBM6 flank (heterotopic) and intracranial (orthotopic) models showed that ponatinib is effective in the flank but not in the intracranial model, despite a relatively high brain-to-plasma ratio. In vitro binding studies indicated that flank tumor had a higher free (unbound) drug fraction than normal brain. The total and free drug concentrations, along with the tissue-to-plasma ratio (Kp) and its unbound derivative (Kp,uu), were consistently higher in the flank tumor than the normal brain at 1 and 6 hours after a single dose in GBM6 flank xenografts. In the orthotopic xenografts, the intracranial tumor core displayed higher Kp and Kp,uu values compared with the brain-around-tumor (BAT). The free fractions and the total drug concentrations, hence free drug concentrations, were consistently higher in the core than in the BAT at 1 and 6 hours postdose. The delivery disadvantages in the brain and BAT were further evidenced by the low total drug concentrations in these areas that did not consistently exceed the in vitro cytotoxic concentration (IC50). Taken together, the regional differences in free drug exposure across the intracranial tumor may be responsible for compromising efficacy of ponatinib in orthotopic GBM6.

Risk of Delayed Lymph Node Metastasis in Clinically N0 Esthesioneuroblastoma

Objective To determine both the rate of delayed cervical lymph node metastasis in patients with esthesioneuroblastoma (ENB) and a clinically N0 untreated neck and the effectiveness of salvage treatment. Design Retrospective review. Setting Tertiary academic medical center. Participants All patients from January 1, 1965, to December 31, 2010, who received definitive treatment for ENB. Main Outcome Measures The study involved 52 patients: 27 (52%) patients underwent surgery and adjuvant radiotherapy (SART) to the primary site only and 25 (48%) underwent surgery alone (SA) as treatment of the primary site, without elective neck dissection. Results Median follow‐up for the SART group was 10 years versus 15.7 years for the SA group. The 10‐year delayed cervical lymph node metastasis estimate is 41%. With median follow‐up of 47 months after salvage treatment, the 4‐year cervical lymph node recurrence‐free survival estimate is 70%; the 5‐year overall survival estimate is 39%. Conclusions Delayed cervical lymph node metastases are common, indolent, and salvaged effectively in most patients. We propose that patients with ENB and clinically N0 cervical lymph nodes may choose to forego elective neck dissection or elective neck radiotherapy in favor of neck observation within their initial treatment.

Characteristics and long-term outcomes of head and neck squamous cell carcinoma after solid organ transplantation

INTRODUCTION Immunosuppression after solid organ transplant prevents graft rejection, but leads to increased incidence of various malignancies including head and neck squamous cell carcinoma (HNSCC). Outcomes of patients with post-transplant HNSCC are unknown. MATERIALS AND METHODS We retrospectively identified patients who developed HNSCC after solid organ transplant between 1995 and 2010. Adults with pathology-proven HNSCC and adequate follow up were included. Median overall survival and progression free survival were analyzed using the Kaplan-Meier method. The prognostic effect of variables was studied with Cox proportional hazards models. RESULTS Thirty-three patients met study inclusion criteria. The median time to diagnosis of HNSCC after transplant was 5.9years. The primary site was oral cavity in 15 patients, oropharynx in 10, larynx in 3, hypopharynx in 2, parotid in 2 and unknown in 1 patient. Eighty-eight percent underwent upfront surgical resection. Of those, sixty-six percent received adjuvant therapy. Six percent of patients had definitive chemoradiation. Treatment was well tolerated and did not lead to graft rejection. The 5-year overall survival rate was 45% and 37% for localized and locally advanced disease respectively. Seventy-five percent of patients with oropharyngeal tumors were HPV-positive and they had better outcomes (5-year overall survival rate of 67%). In multivariate analysis, age ≥60years was a negative predictor of survival (HR 2.7; 95% CI, 1.1-6.5; P=0.03). CONCLUSIONS Patients with post-transplant HNSCC have relatively poor survival and high risk of locoregional and distant recurrence. HPV- positive oropharyngeal tumors continue to have better outcomes in this population.

Treatment outcomes of squamous cell carcinoma of the oral cavity in young adults

OBJECTIVES The natural history of squamous cell carcinoma (SCC) of the oral cavity (OC) in young adults is unknown. We sought to provide an updated report on treatment outcomes of patients with OC SCC who were 40 years or younger. MATERIALS AND METHODS We performed a retrospective analysis of 124 consecutive patients with primary OC SCC treated at Mayo Clinic (1980-2014). Patient and tumor characteristics and treatment approach were abstracted from patient charts. RESULTS Median patient age was 35 years (range, 19-40 years). The most common primary site was oral tongue (107 patients; 86.3%). Most patients (101; 81.5%) underwent wide local excision. Surgery alone was curative in 77 patients (62.1%); 47 (37.9%) received radiotherapy, and 26 (21%) received chemotherapy. Five-year overall survival (OS) was 78.1%; 10-year OS was 76.9%. Five-year disease-free survival (DFS) was 66.6%; 5-year local control was 87.6%; and 5-year locoregional control was 78.5%. On multivariable analysis, factors associated with worse OS and DFS were higher pathologic T stage (P = .008), lymph node positivity (P < .001), and disease recurrence (P < .001). CONCLUSION Young adults with primary OC SCC may be treated with a similar treatment approach as older adults.

Magnitude of benefit for adjuvant radiotherapy following minimally invasive surgery in intermediate to high risk HPV-positive oropharyngeal squamous cell carcinoma

OBJECTIVE To determine the outcomes and toxicities of minimally-invasive surgery with adjuvant intensity-modulated radiotherapy +/- chemotherapy (AT) compared to definitive surgical therapy (ST) in a contemporary cohort of HPV-positive oropharyngeal squamous cell carcinoma (OPSCC). METHODS From 2005 to 2013, a consecutive cohort of 190 HPV-positive OPSCC patients was retrospectively reviewed from multi-institutional databases maintained by the Departments of Otorhinolaryngology and Radiation Oncology. A total of 116 AT patients and 42 ST patients with intermediate or high risk pathologic features were included in the final analysis. All patients received minimally invasive surgery. Time to recurrence and time to death from the onset of surgery were evaluated. Toxicity data collected included dysphagia or xerostomia requiring feeding tube placement >6 months, or mandibular osteonecrosis requiring surgery or hyperbaric oxygen. RESULTS All AT patients received IMRT to a median dose of 60 Gy. Chemotherapy delivered to 67.2% of AT patients. AT group included more high-risk patients given higher nodal classification (p = 0.005) and extracapsular extension (p = 0.0005). AT improved disease-free survival (HR 2.77, CI 1.22-6.28; p = 0.02) and local-regional control (HR 14.83, CI 3.240-67.839; p = 0.001). Disease-free survival with AT and tumor extracapsular extension was improved when compared to ST (HR of 4.34, CI 1.540-12.213; p = 0.006). Dysphagia or mandibular osteonecrosis toxicity after AT vs. ST of 19.0% vs. 2.4%. CONCLUSIONS AT improved local-regional control and disease-free survival but was associated with greater toxicity. The recurrence benefit was most pronounced in tumors with extracapsular extension.