Developing strategies to inflame tumors is critical for increasing response to immunotherapy. Here, we report that low-dose radiotherapy (LDRT) of murine tumors promotes T-cell infiltration and enables responsiveness to combinatorial immunotherapy in an IFN-dependent manner. Treatment efficacy relied upon mobilizing both adaptive and innate immunity and depended on both cytotoxic CD4+ and CD8+ T cells. LDRT elicited predominantly CD4+ cells with features of exhausted effector cytotoxic cells, with a subset expressing NKG2D and exhibiting proliferative capacity, as well as a unique subset of activated dendritic cells expressing the NKG2D ligand RAE1. We translated these findings to a phase I clinical trial administering LDRT, low-dose cyclophosphamide, and immune checkpoint blockade to patients with immune-desert tumors. In responsive patients, the combinatorial treatment triggered T-cell infiltration, predominantly of CD4+ cells with Th1 signatures. Our data support the rational combination of LDRT with immunotherapy for effectively treating low T cell–infiltrated tumors. Significance: Low-dose radiation reprogrammed the tumor microenvironment of tumors with scarce immune infiltration and together with immunotherapy induced simultaneous mobilization of innate and adaptive immunity, predominantly CD4+ effector T cells, to achieve tumor control dependent on NKG2D. The combination induced important responses in patients with metastatic immune-cold tumors. This article is highlighted in the In This Issue feature, p. 1

Abiraterone acetate plus prednisolone (AAP) previously demonstrated improved survival in STAMPEDE, a multiarm, multistage platform trial in men starting long‐term hormone therapy for prostate cancer. This long‐term analysis in metastatic patients was planned for 3 years after the first results. Standard‐of‐care (SOC) was androgen deprivation therapy. The comparison randomised patients 1:1 to SOC‐alone with or without daily abiraterone acetate 1000 mg + prednisolone 5 mg (SOC + AAP), continued until disease progression. The primary outcome measure was overall survival. Metastatic disease risk group was classified retrospectively using baseline CT and bone scans by central radiological review and pathology reports. Analyses used Cox proportional hazards and flexible parametric models, accounting for baseline stratification factors. One thousand and three patients were contemporaneously randomised (November 2011 to January 2014): median age 67 years; 94% newly‐diagnosed; metastatic disease risk group: 48% high, 44% low, 8% unassessable; median PSA 97 ng/mL. At 6.1 years median follow‐up, 329 SOC‐alone deaths (118 low‐risk, 178 high‐risk) and 244 SOC + AAP deaths (75 low‐risk, 145 high‐risk) were reported. Adjusted HR = 0.60 (95% CI: 0.50‐0.71; P = 0.31 × 10⁻⁹) favoured SOC + AAP, with 5‐years survival improved from 41% SOC‐alone to 60% SOC + AAP. This was similar in low‐risk (HR = 0.55; 95% CI: 0.41‐0.76) and high‐risk (HR = 0.54; 95% CI: 0.43‐0.69) patients. Median and current maximum time on SOC + AAP was 2.4 and 8.1 years. Toxicity at 4 years postrandomisation was similar, with 16% patients in each group reporting grade 3 or higher toxicity. A sustained and substantial improvement in overall survival of all metastatic prostate cancer patients was achieved with SOC + abiraterone acetate + prednisolone, irrespective of metastatic disease risk group.

Limited data is available on the role, and extent of, postchemotherapy lymphadenectomy (PC-LND) in patients with clinical evidence of pelvic (cN1-3) or retroperitoneal (RP) lymph node spread from urothelial bladder carcinoma. To compare the outcomes of operated versus nonoperated patients after first-line chemotherapy. Data from 34 centers was collected, totaling 522 patients, treated between January 2000 and June 2015. Criteria for patient selection were the following: bladder primary tumor, lymph node metastases (pelvic±RP) only, first-line platinum-based chemotherapy given. LND (with cystectomy) versus observation after first-line chemotherapy for metastatic urothelial bladder carcinoma. Overall survival (OS) was the primary endpoint. Multiple propensity score techniques were adopted, including 1:1 propensity score matching and inverse probability of treatment weighting. Additionally, the inverse probability of treatment weighting analysis was performed with the inclusion of the covariates, that is, with doubly robust estimation. Overall, 242 (46.4%) patients received PC-LND and 280 (53.6%) observation after chemotherapy. There were 177 (33.9%) and 345 (66.1%) patients with either RP or pelvic LND only, respectively. Doubly robust estimation-adjusted comparison was not significant for improved OS for PC-LND (hazard ratio [HR]: 0.86, 95% confidence interval [CI]: 0.56-1.31, p=0.479), confirmed by matched analysis (HR: 0.91, 95% CI: 0.60-1.36, p=0.628). This was also observed in the RP subgroup (HR: 1.12, 95% CI: 0.68-1.84). The retrospective nature of the data and the heterogeneous patient population were the major limitations. Although there were substantial differences between the two groups, after accounting for major confounders we report a nonsignificant OS difference with PC-LND compared with observation only. These findings may be hypothesis-generating for future prospective trials. We found no differences in survival by adding postchemotherapy lymphadenectomy in patients with pelvic or retroperitoneal lymph node metastatic bladder cancer. The indication to perform postchemotherapy lymphadenectomy in the most suitable patients requires additional studies.

Reduced-dose CT during the follow-up of young oncology patients should be reconstructed with MBIR to ensure diagnostic quality. Elevated body mass index does not hamper the quality of reduced-dose CT.

Objectives: We conducted a phase I/II prospective trial to determine whether stereotactic dose escalation to the dominant intra-prostatic nodule (DIN) up to 50 Gy incorporating a rectal balloon spacer is safe, does not affect patient quality of life, and preserves local control in patients with intermediate-high risk PCa. Methods: Eligible patients included males with stage ≤T3b localized disease, a prostate-specific antigen (PSA) level ≤50 , International Prostate Symptom Score (IPSS) ≤14, and a gland volume ≤70 cm3. Patients underwent perirectal spacer placement, followed by a planning MRI and were subsequently treated with SBRT doses of 36.25 Gy in five fractions to the whole prostate while simultaneously escalating doses to the magnetic resonance image visible DIN up to 50 Gy. Primary endpoint: safety. Secondary endpoints: biochemical control, quality of life (QofL), and dosimetry outcome. Results: Nine patients were treated in the Phase I part of the study. Dose limiting toxicities (DLTs) were not observed. Further characterization of tolerability and efficacy was conducted in the subsequent 24 patients irradiated at the recommended Phase II dose (50 Gy, RP2D). At a median follow-up of 61 months, biochemical control is 69%. Grade 1 and 2 acute GU and GI toxicity was 57.5 and 15%, and 24.2 and 6.1%, respectively. Grade 1 and 2 late GU and GI toxicity was 66.6 and 12.1%, and 15.1 and 3%, respectively. No Grade 3 or higher toxicity was reported. QofL data confirmed physician’s reported side effects. Dosimetry analysis showed adherence to the doses prescribed in the protocol. Conclusions: SBRT of the whole prostate with 36.25 Gy in 5 fractions and dose escalation to 50 Gy to the DIN, when combined with a peri-rectal balloon spacer, was tolerable and established the RP2D. QofL analysis showed minimal negative impact in GU, GI, and sexual domains. Advances in knowledge: Extreme hypofractionated prostate radiation therapy with focal dose escalation to the DIN is well tolerated with efficacy comparable to normal fractionated radiation therapy.

Depending on the pathological findings, up to 60% of prostate cancer patients who undergo radical prostatectomy (RP) will develop biochemical relapse and require further local treatment. Radiotherapy (RT) immediately after RP may potentially eradicate any residual localized microscopic disease in the prostate bed, and it is associated with improved biochemical, clinical progression free survival, and overall survival in patients with high-risk pathological features according to published randomized trials. Offering immediate adjuvant RT to all men with high-risk pathological factors we are over-treating around 50% of patients who would anyway be cancer-free, exposing them to unnecessary toxicity and adding costs to the health care system. The current dilemma is, thus, whether to deliver adjuvant immediate RT solely on the basis of high-risk pathology, but in the absence of measurable prostate-specific antigen, or whether early salvage radiotherapy would yield equivalent outcomes. Randomized trials are ongoing to definitely answer this question. Retrospective analyses suggest that there is a dose–response favoring doses >70 Gy to the prostate bed. The evidence regarding the role of androgen deprivation therapy is emerging, and ongoing randomized trials are underway.