Stereotactic Magnetic Resonance-Guided Daily Adaptive Radiation Therapy for Localized Prostate Cancer: Acute and Late Patient-Reported Toxicity Outcomes.

Purpose: To report acute and late bowel, urinary, and sexual dysfunction patient-reported outcome measures, among patients with localized prostate cancer who underwent stereotactic magnetic resonance-guided daily adaptive radiation therapy (SMART). Methods and Materials: All patients who completed a baseline 12-item Patient-Reported Outcomes Version of the Common Terminology Criteria for Adverse Events questionnaire, before undergoing SMART with 36.25 Gy in 5 fractions, were subsequently followed up with the same graded questionnaire at set time points. Latest prostate-specific antigen levels were recorded. The percentage of patients who reported no change from their baseline adverse event (AE) or reported a new ≥ "frequent or almost constant" or "severe grade or higher" AE grade during follow-up was calculated. The maximum 12-item Patient-Reported Outcomes Version of the Common Terminology Criteria for Adverse Events grade for each item was recorded for each patient. The percentage of toxicity levels for each separate AE item at set time points was calculated. Results: The total number of patients was 69 with a median follow-up of 27 months. Median age of the cohort was 73 years (range, 54-85 years). The median pretreatment prostate-specific antigen level, T stage, and Gleason score were 7.5 mmol/L (range, 4.5-32 mmol/L), T2b (range, T2-T3b), and 7 (3 + 4; range, 6-9), respectively. No patient had biochemical failure during follow-up. Regarding bowel symptoms, >80% of men reported no change from baseline toxicity during follow-up. New ≥ frequent or almost constant diarrhea was reported in 9% of patients. "Almost constant" diarrhea peaked at 1 month but was absent at >33 months. Regarding urinary symptoms, increased urinary urgency was the most common complaint (39%). Twenty percent of men reported new ≥ frequent or almost constant urinary urgency incidence peaking at 1 month but absent at >33 months. New "severe" sexual dysfunction was seen in 26% of patients and was persistent at >33 months. Conclusions: Our study is one the largest patient-reported outcomes study after prostate SMART. It shows acceptable levels of toxicity even up to 2 years after treatment.

The Landscape of Stereotactic Ablative Radiotherapy (SABR) for Renal Cell Cancer (RCC).

Renal cell cancer (RCC) has traditionally been considered radioresistant. Because of this, conventional radiotherapy (RT) has been predominantly relegated to the palliation of symptomatic metastatic disease. The implementation of stereotactic ablative radiotherapy (SABR) has made it possible to deliver higher ablative doses safely, shifting the renal radioresistance paradigm. SABR has increasingly been adopted into the multidisciplinary framework for the treatment of locally recurrent, oligoprogressive, and oligometastatic disease. Furthermore, there is growing evidence of SABR as a non-invasive definitive therapy in patients with primary RCC who are medically inoperable or who decline surgery, unsuited to invasive ablation (surgery or percutaneous techniques), or at high-risk of requiring post-operative dialysis. Encouraging outcomes have even been reported in cases of solitary kidney or pre-existing chronic disease (poor eGFR), with a high likelihood of preserving renal function. A review of clinical evidence supporting the use of ablative radiotherapy (SABR) in primary, recurrent, and metastatic RCC has been conducted. Given the potential immunogenic effect of the high RT doses, we also explore emerging opportunities to combine SABR with systemic treatments. In addition, we explore future directions and ongoing clinical trials in the evolving landscape of this disease.

Cardiopulmonary resuscitation discussions with patients admitted to acute oncology wards: A national audit of current practice.

OBJECTIVES: To map current practice regarding discussions around resuscitation across England and Scotland in patients with cancer admitted acutely to hospital and to demonstrate the value of medical students in rapidly collecting national audit data. METHODS: Collaborators from the Macmillan medical student network collected data from 251 patient encounters across eight hospitals in England and Scotland. Data were collected to identify whether discussion regarding resuscitation was documented as having taken place during inpatient admission to acute oncology. As an audit standard, it was expected that all patients should be invited to discuss resuscitation within 24 hr of admission. RESULTS: Resuscitation discussions were had in 43.1% of admissions and of these 64.0% were within 24 hr; 27.6% of all admissions. 6.5% of patients had a "do not attempt resuscitation" order prior to admission with a difference noted between patients receiving palliative and curative treatment (8.5% and 0.39%, respectively, p < .05). Discussions regarding escalation of care took place in only 29.3% of admissions. CONCLUSIONS: These data highlight deficiencies in the number of discussions regarding resuscitation that are being conducted with cancer patients that become acutely unwell. It also demonstrates the value of medical student collaboration in rapidly collecting national audit data.

Predicting the myelotoxicity of chemotherapy: the use of pretreatment O6-methylguanine-DNA methyltransferase determination in peripheral blood mononuclear cells.

To assess the value of pretreatment O6-methylguanine-DNA methyltransferase (MGMT) expression in peripheral blood mononuclear cells (PBMCs) in predicting haematological toxicity with O6-alkylating agent chemotherapy, we explored this relationship retrospectively in melanoma patients. Ninety-three patients treated with temozolomide or dacarbazine in four clinical trials were assessed, and a model of the interaction between MGMT expression and haematological toxicity was constructed. Nadir white-cell and platelet counts were related to, and hence could be predicted from, pretreatment MGMT. Leucopenia and thrombocytopenia were more prevalent amongst patients with low pretreatment MGMT, according to the highest grades of toxicity experienced and/or the dose intensity patients could sustain. Addition of interferon to chemotherapy or compression of the temozolomide schedule increased the toxicity. The model also predicts significant myelotoxicity where PBMC MGMT is inactivated, consistent with the experience in the clinic with lomeguatrib and O6-benzylguanine. Determination of MGMT in PBMC can identify patients at greatest risk of toxicity or who are suitable for dose intensification.

Tumor O(6)-methylguanine-DNA methyltransferase inactivation by oral lomeguatrib.

PURPOSE: A major mechanism of resistance to chlorethylnitrosureas and methylating agents involves the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT). We sought to determine the dose of oral 6-(4-bromo-2-thienyl) methoxy purin-2-amine (lomeguatrib), a pseudosubstrate inactivator of MGMT, required to render active protein undetectable 12 hours after dosing in prostate, primary central nervous system (CNS), and colorectal cancer patients. EXPERIMENTAL DESIGN: Lomeguatrib was administered orally as a single dose (20-160 mg) approximately 12 hours before tumor resection. Dose escalation was projected to continue until grade 2 toxicity or until complete inactivation of tumor MGMT was encountered. Total MGMT protein levels were quantified by ELISA, and active protein levels were quantified by biochemical assay. MGMT promoter methylation was determined in glioblastoma DNA by methylation-specific PCR. RESULTS: Thirty-seven patients were dosed with lomeguatrib, and 32 informative tumor samples were obtained. Mean total MGMT level varied between tumor types: 554 +/- 404 fmol/mg protein (+/-SD) for prostate cancer, 87.4 +/- 40.3 fmol/mg protein for CNS tumors, and 244 +/- 181 fmol/mg protein for colorectal cancer. MGMT promoter hypermethylation did not correlate with total protein expression. Consistent total MGMT inactivation required 120 mg of lomeguatrib in prostate and colorectal cancers. Complete consistent inactivation in CNS tumors was observed only at the highest dose of lomeguatrib (160 mg). CONCLUSIONS: Total MGMT inactivation can be achieved in prostate, primary CNS, and colorectal cancers with a single administration of 120 or 160 mg lomeguatrib. The dose needed did not correlate with mean total MGMT protein concentrations. One hundred twenty to 160 mg/d of lomeguatrib should be administered to achieve total MGMT inactivation in future studies.

Randomized trial of the combination of lomeguatrib and temozolomide compared with temozolomide alone in chemotherapy naive patients with metastatic cutaneous melanoma.

PURPOSE: To evaluate tumor response, pharmacodynamic effects, and safety of a combination of lomeguatrib (LM), an O6-methylguanine DNA-methyltransferase (MGMT) inactivator, and temozolomide (TMZ), TMZ alone, and LM/TMZ after disease progression on TMZ alone in patients with advanced melanoma. PATIENTS AND METHODS: Patients with unresectable stage III or IV cutaneous melanoma who had no prior systemic chemotherapy were randomly assigned to receive either 40 to 80 mg LM and 125 mg/m2 TMZ or 200 mg/m2 TMZ on days 1 through 5 of each 28-day treatment cycle. Drugs were administered orally for up to six cycles of treatment. Patients on TMZ alone were offered LM/TMZ at progression, if fit enough to receive treatment. RESULTS: One hundred four patients were enrolled, with 52 in each trial arm. Twenty-seven TMZ-treated patients received LM/TMZ after progression on TMZ. Unexpectedly, analysis of tumor biopsies showed rapid recovery of MGMT after LM/TMZ with 40 mg/d LM. Therefore, doses of LM were escalated to 60 then 80 mg/d. Tumor response rates were 13.5% with LM/TMZ and 17.3% with TMZ alone. No patient responded to LM/TMZ having progressed through TMZ. Median time to disease progression was 65.5 days for LM/TMZ and 68 days for TMZ. All treatments were well tolerated, although hematologic and gastrointestinal adverse events were common. A higher incidence of hematological adverse events was observed in the LM/TMZ combination arm. CONCLUSION: The efficacy of LM and TMZ in the current dosing schedule is similar to that of TMZ alone. To maintain MGMT depletion in tumor dosing of LM needs to be continued beyond that of TMZ.

Chemotherapy for colorectal cancer in the metastatic and adjuvant setting: past, present and future.

There have been significant advances in the use of chemotherapy in the treatment of colorectal cancer patients over the last 20 years. Initial improvements in treatment were made with increased understanding of the pharmacology of 5-fluorouracil and the discovery of modulators of its activity (e.g., leucovorin). However, in the last few years the discovery of new cytotoxic drugs with efficacy in large bowel cancer (e.g., oxaliplatin and irinotecan) and monoclonal antibodies (e.g., bevacizumab and cetuximab) have significantly improved patient outcome and prognosis. Systemic chemotherapy in the metastatic setting has been shown to prolong survival and improve quality of life. Chemotherapy now also has a clear role as an adjunct to surgery to improve survival in stage III and certain 'high-risk' stage II colorectal cancer patients. The evolution of chemotherapy use, current practice in the metastatic and adjuvant setting and possible future directions are discussed.

Exploiting the role of O6-methylguanine-DNA-methyltransferase (MGMT) in cancer therapy.

Improving the efficacy of standard chemotherapy by targeting DNA repair mechanisms remains an important area of research. O6-methylguanine-DNA-methyltransferase (MGMT), which repairs alkylating agent damage, is one such target. Downregulation of the gene through epigenetic silencing has been shown to predict response to alkylating agent therapy in selected malignancies. Platinums have also been found to downregulate MGMT expression and this approach is currently under exploration. Another way to deplete O6-alkylguanine DNA alkyltransferase (AGT) levels is to modify methylating agent scheduling. Extended dosing has met with early favourable results. However, pseudosubstrates used to inhibit AGT activity have had limited success because of dose-limiting myelotoxicity. Topoisomerase I is 'trapped' on DNA by alteration of ligation kinetics following alkylating agent damage, leading to interest in combining AGT inhibitors or O6-alkylating agents with topoisomerase I inhibitors. DNA repair by AGT is an interesting target for cancer therapy that remains to be fully evaluated. The best results are likely to be achieved where its inhibition is part of treatment targeting multiple DNA damage processing pathways.