Phase 1 trial of adavosertib (AZD1775) in combination with concurrent radiation and cisplatin for intermediate-risk and high-risk head and neck squamous cell carcinoma.

BACKGROUND: Adavosertib (AZD1775) is an inhibitor of the Wee1 kinase. The authors conducted a phase 1b trial to evaluate the safety of adavosertib in combination with definitive chemoradiotherapy for patients with newly diagnosed, intermediate-risk/high-risk, locally advanced head and neck squamous cell carcinoma (HNSCC). METHODS: Twelve patients with intermediate-risk/high-risk HNSCC were enrolled, including those with p16-negative tumors of the oropharynx, p16-positive tumors of the oropharynx with ≥10 tobacco pack-years, and tumors of the larynx/hypopharynx regardless of p16 status. All patients were treated with an 8-week course of concurrent intensity-modulated radiotherapy at 70 grays (Gy) (2 Gy daily in weeks 1-7), cisplatin 30 mg/m2 weekly (in weeks 1-7), and adavosertib (twice daily on Monday, Tuesday, and Wednesday of weeks 1, 2, 4, 5, 7, and 8). The primary objective was to determine the maximum tolerated dose and the recommended phase 2 dose of adavosertib given concurrently with radiation and cisplatin. Secondary objectives were to determine the 12-week objective response rate and progression-free and overall survival. RESULTS: Three patients (25%) experienced a dose-limiting toxicity, including febrile neutropenia (n = 2) and grade 4 thromboembolism (n = 1). Two dose-limiting toxicities occurred with adavosertib at 150 mg. The median follow-up was 14.7 months. The 12-week posttreatment objective response rate determined by positron emission tomography/computed tomography was 100%. The 1-year progression-free and overall survival rates were both 90%. The maximum tolerated dose of adavosertib was 100 mg. CONCLUSIONS: Adavosertib 100 mg (twice daily on Monday, Tuesday, and Wednesday of weeks 1, 2, 4, 5, 7, and 8), in combination with 70 Gy of intensity-modulated radiotherapy and cisplatin 30 mg/m2 , is the recommended phase 2 dose for patients with HNSCC.

Radiation therapy for infants with cancer.

The clinical outcomes for infants with malignant tumors are often worse than older children due to a combination of more biologically aggressive disease in some cases, and increased toxicity-or deintensification of therapies due to concern for toxicity-in others. Especially in infants and very young children, finding the appropriate balance between maximizing treatment efficacy while minimizing toxicity-in particular late side effects-is crucial. We review here the management of malignant tumors in infants and very young children, focusing on central nervous system (CNS) malignancies and rhabdomyosarcoma.

Impact of race, ethnicity, and socioeconomic factors on receipt of radiation after breast conservation surgery: analysis of the national cancer database.

INTRODUCTION: Many eligible women with invasive breast cancer do not receive recommended adjuvant radiation (RT), despite its role in local control and overall survival. We examined trends in RT use over 10 years, and the impact of sociodemographic factors on the receipt of standard-of-care RT, using the National Cancer Database (NCDB). MATERIALS/METHODS: Women under age 70 with invasive breast cancer who underwent BCS from 2004 to 2014 were analyzed. Receipt of RT was evaluated in the whole cohort and by time period to identify temporal trends. Multiple logistic regression models were used to assess associations between factors such as race, insurance status, ethnicity, and receipt of RT. RESULTS: A total of 501,733 patients met eligibility criteria. The percentage of patients undergoing adjuvant RT increased from 86.7% in 2004 to 92.4% in 2012, and then decreased in 2013 and 2014 to 88.9%. On univariate analysis, patients of white race were significantly more likely to receive RT compared with patients of black race (90.4% vs 86.9%, p < 0.0001), as were non-Hispanic women compared to Hispanic patients (90.2% vs. 85.3%, p < 0.0001). On multivariate analysis, race, ethnicity, insurance status, education level, and age remained significantly associated with receipt of RT. On temporal analysis, gaps remained stable, with no significant improvements over time. CONCLUSIONS: This analysis suggests a recent decline in guideline-concordant receipt of RT in women under 70, and persistent disparities in the use of RT after BCS by race, ethnicity, and socioeconomic factors. These findings raise concern for a recent detrimental change in patterns of care delivery.

Socioeconomic factors affect the selection of proton radiation therapy for children.

BACKGROUND: Proton radiotherapy remains a limited resource despite its clear potential for reducing radiation doses to normal tissues and late effects in children in comparison with photon therapy. This study examined the impact of race and socioeconomic factors on the use of proton therapy in children with solid malignancies. METHODS: This study evaluated 12,101 children (age ≤ 21 years) in the National Cancer Data Base who had been diagnosed with a solid malignancy between 2004 and 2013 and had received photon- or proton-based radiotherapy. Logistic regression analysis was used to evaluate patient, tumor, and socioeconomic variables affecting treatment with proton radiotherapy versus photon radiotherapy. RESULTS: Eight percent of the patients in the entire cohort received proton radiotherapy, and this proportion increased between 2004 (1.7%) and 2013 (17.5%). Proton therapy was more frequently used in younger patients (age ≤ 10 years; odds ratio [OR], 1.9; 95% confidence interval [CI], 1.6-2.2) and in patients with bone/joint primaries and ependymoma, medulloblastoma, and rhabdomyosarcoma histologies (P < .05). Patients with metastatic disease were less likely to receive proton therapy (OR, 0.4; 95% CI, 0.3-0.6). Patients with private/managed care were more likely than patients with Medicaid or no insurance to receive proton therapy (P < .0001). A higher median household income and educational attainment were also associated with increased proton use (P < .001). Patients treated with proton therapy versus photon therapy were more likely to travel more than 200 miles (13% vs 5%; P < .0001). CONCLUSIONS: Socioeconomic factors affect the use of proton radiotherapy in children. Whether this disparity is related to differences in the referral patterns, the knowledge of treatment modalities, or the ability to travel for therapy needs to be further clarified. Improving access to proton therapy in underserved pediatric populations is essential. Cancer 2017;123:4048-56. © 2017 American Cancer Society.

Controversies in the Therapy of Brain Metastases: Shifting Paradigms in an Era of Effective Systemic Therapy and Longer-Term Survivorship.

OPINION STATEMENT: With the development of therapies that improve extracranial disease control and increase long-term survival of patients with metastatic cancer, effective treatment of brain metastases while minimizing toxicities is becoming increasingly important. An expanding arsenal that includes surgical resection, whole brain radiation therapy, radiosurgery, and targeted systemic therapy provides multiple treatment options. However, significant controversies still exist surrounding appropriate use of each modality in various clinical scenarios and patient populations in the context of cancer care strategies that control systemic disease for increasingly longer periods of time. While whole brain radiotherapy alone is still a reasonable and standard option for patients with multiple metastases, several randomized trials have now revealed that survival is maintained in patients treated with radiosurgery or surgery alone, without upfront whole brain radiotherapy, for up to four brain metastases. Indeed, recent data even suggest that patients with up to 10 metastases can be treated with radiosurgery alone without a survival detriment. In an era of dramatic advances in targeted and immune therapies that control systemic disease and improve survival but may not penetrate the brain, more consideration should be given to brain metastasis-directed treatments that minimize long-term neurocognitive deficits, while keeping in mind that salvage brain therapies will likely be more frequently required. Less toxic therapies now also allow for concurrent delivery of systemic therapy with radiosurgery to brain metastases, such that treatment of both extracranial and intracranial disease can be expedited, and potential synergies between radiotherapy and agents with central nervous system penetration can be harnessed.

Ionizing radiation induces tumor cell lysyl oxidase secretion.

BACKGROUND: Ionizing radiation (IR) is a mainstay of cancer therapy, but irradiation can at times also lead to stress responses, which counteract IR-induced cytotoxicity. IR also triggers cellular secretion of vascular endothelial growth factor, transforming growth factor ß and matrix metalloproteinases, among others, to promote tumor progression. Lysyl oxidase is known to play an important role in hypoxia-dependent cancer cell dissemination and metastasis. Here, we investigated the effects of IR on the expression and secretion of lysyl oxidase (LOX) from tumor cells. METHODS: LOX-secretion along with enzymatic activity was investigated in multiple tumor cell lines in response to irradiation. Transwell migration assays were performed to evaluate invasive capacity of naïve tumor cells in response to IR-induced LOX. In vivo studies for confirming IR-enhanced LOX were performed employing immunohistochemistry of tumor tissues and ex vivo analysis of murine blood serum derived from locally irradiated A549-derived tumor xenografts. RESULTS: LOX was secreted in a dose dependent way from several tumor cell lines in response to irradiation. IR did not increase LOX-transcription but induced LOX-secretion. LOX-secretion could not be prevented by the microtubule stabilizing agent patupilone. In contrast, hypoxia induced LOX-transcription, and interestingly, hypoxia-dependent LOX-secretion could be counteracted by patupilone. Conditioned media from irradiated tumor cells promoted invasiveness of naïve tumor cells, while conditioned media from irradiated, LOX- siRNA-silenced cells did not stimulate their invasive capacity. Locally applied irradiation to tumor xenografts also increased LOX-secretion in vivo and resulted in enhanced LOX-levels in the murine blood serum. CONCLUSIONS: These results indicate a differential regulation of LOX-expression and secretion in response to IR and hypoxia, and suggest that LOX may contribute towards an IR-induced migratory phenotype in sublethally-irradiated tumor cells and tumor progression.

Target Delineation in Postoperative Radiation Therapy for Head and Neck Cancer After Flap Reconstruction.

Delineation of the clinical target volume (CTV) after resection of head and neck cancer can be challenging, especially after flap reconstruction. The main area of contention is whether the entire flap should be included in the CTV. Several case series have reported marginal misses and intraflap failures when the entire flap was not routinely included in the CTV. On the other hand, available data have not convincingly demonstrated a detriment to long-term outcomes using intensity modulated radiotherapy after flap reconstruction. On the contrary, postoperative radiation can facilitate epilation and mucosalization of the flap tissue, reduce flap bulk, and improve long-term esthetic and functional outcomes. Therefore, our standard practice is to include the entire flap in the CTV. In certain scenarios, we may allow for a lower dose to part of flap distant from the resection bed than the flap-tumor bed junction, where recurrences are most likely. We provide three case vignettes describing such scenarios where sparing part of the flap, and more importantly, the nearby uninvolved native tissue, from high-dose radiation may be justified.

Retinopathy, Optic Neuropathy, and Cataract in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review.

PURPOSE: Few reports describe the risks of late ocular toxicities after radiation therapy (RT) for childhood cancers despite their effect on quality of life. The Pediatric Normal Tissue Effects in the Clinic (PENTEC) ocular task force aims to quantify the radiation dose dependence of select late ocular adverse effects. Here, we report results concerning retinopathy, optic neuropathy, and cataract in childhood cancer survivors who received cranial RT. METHODS AND MATERIALS: A systematic literature search was performed using the PubMed, MEDLINE, and Cochrane Library databases for peer-reviewed studies published from 1980 to 2021 related to childhood cancer, RT, and ocular endpoints including dry eye, keratitis/corneal injury, conjunctival injury, cataract, retinopathy, and optic neuropathy. This initial search yielded abstracts for 2947 references, 269 of which were selected as potentially having useful outcomes and RT data. Data permitting, treatment and outcome data were used to generate normal tissue complication probability models. RESULTS: We identified sufficient RT data to generate normal tissue complication probability models for 3 endpoints: retinopathy, optic neuropathy, and cataract formation. Based on limited data, the model for development of retinopathy suggests 5% and 50% risk of toxicity at 42 and 62 Gy, respectively. The model for development of optic neuropathy suggests 5% and 50% risk of toxicity at 57 and 64 Gy, respectively. More extensive data were available to evaluate the risk of cataract, separated into self-reported versus ophthalmologist-diagnosed cataract. The models suggest 5% and 50% risk of self-reported cataract at 12 and >40 Gy, respectively, and 50% risk of ophthalmologist-diagnosed cataract at 9 Gy (>5% long-term risk at 0 Gy in patients treated with chemotherapy only). CONCLUSIONS: Radiation dose effects in the eye are inadequately studied in the pediatric population. Based on limited published data, this PENTEC comprehensive review establishes relationships between RT dose and subsequent risks of retinopathy, optic neuropathy, and cataract formation.

Feasibility of the Audio-Visual Assisted Therapeutic Ambience in Radiotherapy (AVATAR) System for Anesthesia Avoidance in Pediatric Patients: A Multicenter Trial.

PURPOSE: The Audio-Visual Assisted Therapeutic Ambience in Radiotherapy (AVATAR) system was the first published radiation therapy (RT)-compatible system to reduce the need for pediatric anesthesia through video-based distraction. We evaluated the feasibility of AVATAR implementation and effects on anesthesia use, quality of life, and anxiety in a multicenter pediatric trial. METHODS AND MATERIALS: Pediatric patients 3 to 10 years of age preparing to undergo RT at 10 institutions were prospectively enrolled. Children able to undergo at least 1 fraction of RT using AVATAR without anesthesia were considered successful (S). Patients requiring anesthesia for their entire treatment course were nonsuccessful (NS). The PedsQL3.0 Cancer Module (PedsQL) survey assessed quality of life and was administered to the patient and guardian at RT simulation, midway through RT, and at final treatment. The modified Yale Preoperative Anxiety Scale (mYPAS) assessed anxiety and was performed at the same 3 time points. Success was evaluated using the χ2 test. PedsQL and mYPAS scores were assessed using mixed effects models with time points evaluated as fixed effects and a random intercept on the subject. RESULTS: Eighty-one children were included; median age was 7 years. AVATAR was successful at all 10 institutions and with photon and proton RT. There were 63 (78%) S patients; anesthesia was avoided for a median of 20 fractions per patient. Success differed by age (P = .04) and private versus public insurance (P < .001). Both patient (P = .008) and parent (P = .006) PedsQL scores significantly improved over the course of RT for patients aged 5 to 7. Anxiety in the treatment room decreased for both S and NS patients over RT course (P < .001), by age (P < .001), and by S versus NS patients (P < .001). CONCLUSIONS: In this 10-center prospective trial, anesthesia avoidance with AVATAR was 78% in children aged 3 to 10 years, higher than among age-matched historical controls (49%; P < .001). AVATAR implementation is feasible across multiple institutions and should be further studied and made available to patients who may benefit from video-based distraction.

Decoupling diffusional from dimensional control of signaling in 3D culture reveals a role for myosin in tubulogenesis.

We present a novel microfabricated platform to culture cells within arrays of micrometer-scale three-dimensional (3D) extracellular matrix scaffolds (microgels). These microscale cultures eliminate diffusion barriers that are intrinsic to traditional 3D culture systems (macrogels) and enable uniform cytokine stimulation of the entire culture population, as well as allow immunolabeling, imaging and population-based biochemical assays across the relatively coplanar microgels. Examining early signaling associated with hepatocyte growth factor (HGF)-mediated scattering and tubulogenesis of MDCK cells revealed that 3D culture modulates cellular responses both through dimensionality and altered stimulation rates. Comparing responses in 2D culture, microgels and macrogels demonstrated that HGF-induced ERK signaling was driven by the dynamics of stimulation and not by whether cells were in a 2D or 3D environment, and that this ERK signaling was equally important for HGF-induced cell scattering on 2D substrates and tubulogenesis in 3D. By contrast, we discovered a specific HGF-induced increase in myosin expression leading to sustained downregulation of myosin activity that occurred only within 3D contexts and was required for 3D tubulogenesis but not 2D scattering. Interestingly, although absent in cells on collagen-coated plates, downregulation of myosin activity also occurred for cells on collagen gels, but was transient and mediated by a combination of myosin dephosphorylation and enhanced myosin expression. Furthermore, upregulating myosin activity via siRNA targeted to a myosin phosphatase did not attenuate scattering in 2D but did inhibit tubulogenesis in 3D. Together, these results demonstrate that cellular responses to soluble cues in 3D culture are regulated by both rates of stimulation and by matrix dimensionality, and highlight the importance of decoupling these effects to identify early signals relevant to cellular function in 3D environments.

Decreased cell adhesion promotes angiogenesis in a Pyk2-dependent manner.

Angiogenesis is regulated by both soluble growth factors and cellular interactions with the extracellular matrix (ECM). While cell adhesion via integrins has been shown to be required for angiogenesis, the effects of quantitative changes in cell adhesion and spreading against the ECM remain less clear. Here, we show that angiogenic sprouting in natural and engineered three-dimensional matrices exhibited a biphasic response, with peak sprouting when adhesion to the matrix was limited to intermediate levels. Examining changes in global gene expression to determine a genetic basis for this response, we demonstrate a vascular endothelial growth factor (VEGF)-induced upregulation of genes associated with vascular invasion and remodeling when cell adhesion was limited, whereas cells on highly adhesive surfaces upregulated genes associated with proliferation. To explore a mechanistic basis for this effect, we turned to focal adhesion kinase (FAK), a central player in adhesion signaling previously implicated in angiogenesis, and its homologue, proline-rich tyrosine kinase 2 (Pyk2). While FAK signaling had some impact, our results suggested that Pyk2 can regulate both gene expression and endothelial sprouting through its enhanced activation by VEGF in limited adhesion contexts. We also demonstrate decreased sprouting of tissue explants from Pyk2-null mice as compared to wild type mice as further confirmation of the role of Pyk2 in angiogenic sprouting. These results suggest a surprising finding that limited cell adhesion can enhance endothelial responsiveness to VEGF and demonstrate a novel role for Pyk2 in the adhesive regulation of angiogenesis.

The Evolving Role of Radiotherapy for Pediatric Cancers With Advancements in Molecular Tumor Characterization and Targeted Therapies.

Ongoing rapid advances in molecular diagnostics, precision imaging, and development of targeted therapies have resulted in a constantly evolving landscape for treatment of pediatric cancers. Radiotherapy remains a critical element of the therapeutic toolbox, and its role in the era of precision medicine continues to adapt and undergo re-evaluation. Here, we review emerging strategies for combining radiotherapy with novel targeted systemic therapies (for example, for pediatric gliomas or soft tissue sarcomas), modifying use or intensity of radiotherapy when appropriate via molecular diagnostics that allow better characterization and individualization of each patient's treatments (for example, de-intensification of radiotherapy in WNT subgroup medulloblastoma), as well as exploring more effective targeted systemic therapies that may allow omission or delay of radiotherapy. Many of these strategies are still under investigation but highlight the importance of continued pre-clinical and clinical studies evaluating the role of radiotherapy in this era of precision oncology.

Prognostic and Predictive Clinical and Biological Factors in HPV Malignancies.

Human papillomavirus (HPV) causes the majority of oropharyngeal, cervical, and anal cancers, among others. These HPV-associated cancers cause substantial morbidity and mortality despite ongoing vaccination efforts. Aside from the earliest stage tumors, chemoradiation is used to treat most HPV-associated cancers across disease sites. Response rates are variable, and opportunities to improve oncologic control and reduce toxicity remain. HPV malignancies share multiple commonalities in oncogenesis and tumor biology that may inform personalized methods of screening, diagnosis, treatment and surveillance. In this review we discuss the current literature and identify promising molecular targets, prognostic and predictive clinical factors and biomarkers in HPV-associated oropharyngeal, cervical and anal cancer.

Consolidative or palliative whole brain radiation for secondary CNS diffuse large B-Cell lymphoma.

We analyzed 25 patients receiving whole brain radiation (WBRT) for secondary CNS lymphoma (SCNSL), grouped by consolidative intent (after complete/partial response, n = 13) vs. palliative intent (initial CNS treatment, primary refractory disease, or CNS progression, n = 12). Median WBRT dose for the consolidative and palliative cohorts were 24 Gy and 30 Gy, respectively. For 13 patients receiving consolidative WBRT, median OS was 24 months from WBRT and 2-year OS was 64%. Three patients had CNS relapse at 2, 9, and 24 months after consolidative WBRT. For 12 patients receiving palliative WBRT, median OS was 3 months from WBRT and two-year OS was 8%. All 10 patients with neurologic symptoms had documented improvement. In conclusion, consolidative WBRT after chemotherapy response led to reasonable long-term survival and may be an effective strategy for SCNSL, especially transplant-ineligible patients and/or isolated CNS recurrence. Palliative WBRT effectively improved neurologic symptoms, but survival was usually only months.

NTCP modeling and dose-volume correlations for acute xerostomia and dry eye after whole brain radiation.

BACKGROUND: Whole brain radiation (WBRT) may lead to acute xerostomia and dry eye from incidental parotid and lacrimal exposure, respectively. We performed a prospective observational study to assess the incidence/severity of this toxicity. We herein perform a secondary analysis relating parotid and lacrimal dosimetric parameters to normal tissue complication probability (NTCP) rates and associated models. METHODS: Patients received WBRT to 25-40 Gy in 10-20 fractions using 3D-conformal radiation therapy without prospective delineation of the parotids or lacrimals. Patients completed questionnaires at baseline and 1 month post-WBRT. Xerostomia was assessed using the University of Michigan xerostomia score (scored 0-100, toxicity defined as ≥ 20 pt increase) and xerostomia bother score (scored from 0 to 3, toxicity defined as ≥ 2 pt increase). Dry eye was assessed using the Subjective Evaluation of Symptom of Dryness (SESoD, scored from 0 to 4, toxicity defined as ≥ 2 pt increase). The clinical data were fitted by the Lyman-Kutcher-Burman (LKB) and Relative Seriality (RS) NTCP models. RESULTS: Of 55 evaluable patients, 19 (35%) had ≥ 20 point increase in xerostomia score, 11 (20%) had ≥ 2 point increase in xerostomia bother score, and 13 (24%) had ≥ 2 point increase in SESoD score. For xerostomia, parotid V10Gy-V20Gy correlated best with toxicity, with AUC 0.68 for xerostomia score and 0.69-0.71 for bother score. The values for the D50, m and n parameters of the LKB model were 22.3 Gy, 0.84 and 1.0 for xerostomia score and 28.4 Gy, 0.55 and 1.0 for bother score, respectively. The corresponding values for the D50, γ and s parameters of the RS model were 23.5 Gy, 0.28 and 0.0001 for xerostomia score and 32.0 Gy, 0.45 and 0.0001 for bother score, respectively. For dry eye, lacrimal V10Gy-V15Gy were found to correlate best with toxicity, with AUC values from 0.67 to 0.68. The parameter values of the LKB model were 53.5 Gy, 0.74 and 1.0, whereas of the RS model were 54.0 Gy, 0.37 and 0.0001, respectively. CONCLUSIONS: Xerostomia was most associated with parotid V10Gy-V20Gy, and dry eye with lacrimal V10Gy-V15Gy. NTCP models were successfully created for both toxicities and may help clinicians refine dosimetric goals and assess levels of risk in patients receiving palliative WBRT.

Common Error Pathways in CyberKnife™ Radiation Therapy.

Purpose/Objectives: Stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) may be considered "high risk" due to the high doses per fraction. We analyzed CyberKnife™ (CK) SRS and SBRT-related incidents that were prospectively reported to our in-house incident learning system (ILS) in order to identify severity, contributing factors, and common error pathways. Material and Methods: From 2012 to 2019, 221 reported incidents related to the 4,569 CK fractions delivered (5.8%) were prospectively analyzed by our multi-professional Quality and Safety Committee with regard to severity, contributing factors, as well as the location where the incident occurred (tripped), where it was discovered (caught), and the safety barriers that were traversed (crossed) on the CK process map. Based on the particular step in the process map that incidents tripped, we categorized incidents into general error pathways. Results: There were 205 severity grade 1-2 (did not reach patient or no clinical impact), 11 grade 3 (clinical impact unlikely), 5 grade 4 (altered the intended treatment), and 0 grade 5-6 (life-threatening or death) incidents, with human performance being the most common contributing factor (79% of incidents). Incidents most commonly tripped near the time when the practitioner requested CK simulation (e.g., pre-CK simulation fiducial marker placement) and most commonly caught during the physics pre-treatment checklist. The four general error pathways included pre-authorization, billing, and scheduling issues (n= 119); plan quality (n= 30); administration of IV contrast during simulation or pre-medications during treatment (n= 22); and image guidance (n= 12). Conclusion: Most CK incidents led to little or no patient harm and most were related to billing and scheduling issues. Suboptimal human performance appeared to be the most common contributing factor to CK incidents. Additional study is warranted to develop and share best practices to reduce incidents to further improve patient safety.

Auger radiopharmaceutical therapy targeting prostate-specific membrane antigen in a micrometastatic model of prostate cancer.

Auger radiopharmaceutical therapy is a promising strategy for micrometastatic disease given high linear energy transfer and short range in tissues, potentially limiting normal tissue toxicities. We previously demonstrated anti-tumor efficacy of a small-molecule Auger electron emitter targeting the prostate-specific membrane antigen (PSMA), 2-[3-[1-carboxy-5-(4-[125I]iodo-benzoylamino)-pentyl]-ureido]-pentanedioic acid), or 125I-DCIBzL, in a mouse xenograft model. Here, we investigated the therapeutic efficacy, long-term toxicity, and biodistribution of 125I-DCIBzL in a micrometastatic model of prostate cancer (PC). Methods: To test the therapeutic efficacy of 125I-DCIBzL in micrometastatic PC, we used a murine model of human metastatic PC in which PSMA+ PC3-ML cells expressing firefly luciferase were injected intravenously in NSG mice to form micrometastatic deposits. One week later, 0, 0.37, 1.85, 3.7, 18.5, 37, or 111 MBq of 125I-DCIBzL was administered (intravenously). Metastatic tumor burden was assessed using bioluminescence imaging (BLI). Long-term toxicity was evaluated via serial weights and urinalysis of non-tumor-bearing mice over a 12-month period, as well as final necropsy. Results: In the micrometastatic PC model, activities of 18.5 MBq 125I-DCIBzL and above significantly delayed development of detectable metastatic disease by BLI and prolonged survival in mice. Gross metastases were detectable in control mice and those treated with 0.37-3.7 MBq 125I-DCIBzL at a median of 2 weeks post-treatment, versus 4 weeks for those treated with 18.5-111 MBq 125I-DCIBzL (P<0.0001 by log-rank test). Similarly, treatment with ≥18.5 MBq 125I-DCIBzL yielded a median survival of 11 weeks, compared with 6 weeks for control mice (P<0.0001). At 12 months, there was no appreciable toxicity via weight, urinalysis, or necropsy evaluation in mice treated with any activity of 125I-DCIBzL, which represents markedly less toxicity than the analogous PSMA-targeted α-particle emitter. Macro-to-microscale dosimetry modeling demonstrated lower absorbed dose in renal cell nuclei versus tumor cell nuclei due to lower levels of drug uptake and cellular internalization in combination with the short range of Auger emissions. Conclusion: PSMA-targeted radiopharmaceutical therapy with the Auger emitter 125I-DCIBzL significantly delayed development of detectable metastatic disease and improved survival in a micrometastatic model of PC, with no long-term toxicities noted at 12 months, suggesting a favorable therapeutic ratio for treatment of micrometastatic PC.

Novel Strategies to Effectively De-escalate Curative-Intent Therapy for Patients With HPV-Associated Oropharyngeal Cancer: Current and Future Directions.

The treatment of patients with HPV-associated oropharyngeal cancer (HPV-OPC) is rapidly evolving and challenging the standard of care of definitive radiotherapy with concurrent cisplatin. There are numerous promising de-escalation strategies under investigation, including deintensified definitive chemoradiotherapy, transoral surgery followed by de-escalated adjuvant therapy, and induction chemotherapy followed by de-escalated locoregional therapy. Definitive radiotherapy alone or with cetuximab is not recommended for curative-intent treatment of patients with locally advanced HPV-OPC. The results of ongoing phase III studies are awaited to help answer key questions and address ongoing controversies to transform the treatment of patients with HPV-OPC. Strategies for de-escalation under investigation include the incorporation of immunotherapy and the use of novel biomarkers for patient selection for de-escalation.

Concurrent Definitive Immunoradiotherapy for Patients with Stage III-IV Head and Neck Cancer and Cisplatin Contraindication.

PURPOSE: Although cisplatin plus radiotherapy is a standard treatment of locally advanced head and neck squamous cell carcinoma (LA-HNSCC), cisplatin contraindication is common. Radiation elicits and promotes tumor-directed immune stimulation, which may potentiate anti-PD-1 therapy. We provide the first efficacy report of combined pembrolizumab and definitive radiotherapy in LA-HNSCC. PATIENTS AND METHODS: This single-arm, multi-institution, phase II study (NCT02609503) enrolled 29 cisplatin-ineligible patients. Patients received radiotherapy concurrently with three cycles of pembrolizumab 200 mg every 3 weeks followed by three adjuvant cycles. The primary endpoint was a progression-free survival (PFS) of ≥16 months. Correlative studies included peripheral blood flow cytometry and Luminex cytokine profiling. RESULTS: Reasons for cisplatin ineligibility included otopathy (69.0%), nephropathy (20.7%), and neuropathy (6.9%). With median follow-up of 21 months, estimated 24-month PFS and overall survival rates were 71% (95% confidence interval, 49%-84%) and 75% (51%-88%). The primary PFS endpoint has exceeded the hypothesis and its median has not been reached. Toxicities were typical of radiotherapy; however, high rates of grade 3/4 lymphopenia (58.6%) were observed. Flow cytometry revealed a relative decline in CD4 T cells and B cells, but not CD8 T cells. Upon treatment, frequencies of transitional B cells and tissue-like memory B cells increased, while resting memory B cells decreased. Patients with progression had greater percentages of baseline naïve B cells and fewer marginal zone B cells. CONCLUSIONS: Pembrolizumab and radiotherapy is efficacious in LA-HNSCC and should be evaluated in a randomized trial. The observed changes in B-cell markers deserve further study both as potential biomarkers and as therapeutic targets.