Interim Analysis of DD3: A Phase IB/II Trial of Dose-Deescalated 3-Fraction SBRT for Centrally Located Lung Cancer

PURPOSE/OBJECTIVE(S)

Prior studies suggested excessive toxicity for central lung tumors treated with 3-fraction stereotactic body radiation therapy (SBRT). This may be related to the high biologically equivalent dose assuming alpha/beta of 10 (BED) of 54 Gy in 3 fractions (BED = 151.2), as 50-60 Gy in 5 fractions (BED = 100.0-132.0) was well-tolerated in RTOG 0813. We initiated a prospective phase IB/II trial to test the hypothesis that a dose-deescalated regimen of 45 Gy in 3 fractions (BED 112.5) would be safe and efficacious in central lung tumors.

MATERIALS/METHODS

We enrolled patients with primary or secondary lung tumors ≤5cm in a central but not ultra-central tumor location defined as within 2 cm of (but not abutting) tracheobronchial tree, esophagus, or heart. Patients were either medically inoperable or refused surgical intervention. Co-primary endpoints were safety and efficacy, defined as local control (LC). Secondary endpoints included lobar control, regional control (LRC), distant control (DC), progression-free survival (PFS), cancer-specific survival (CSS), and overall survival (OS). Organ-at-risk dose constraints were consistent with those of RTOG 0236. The Bayesian predictive probability approach was utilized for continuous monitoring after 10 patients were treated and have mature assessment of toxicity, after which interim analysis was planned. We recommended terminating the trial for safety if there was sufficient evidence that the rate of grade ≥3 was greater than 0.25 (predictive probability >0.80).

RESULTS

As of the data cut-off date of 1/26/23, the trial was open for 34 months (including a nearly-immediate suspension due to the COVID-19 pandemic). A total of 17 patients have been treated on protocol with a median follow-up of 12 months. No grade ≥3 adverse events attributable to SBRT have occurred to date, though one patient died of unrelated cardiac arrhythmias 1 month after SBRT completion (Table 1). Maximum CTCAE grade 2 adverse events attributable to SBRT occurred in 17.6% of patients. The predictive probability of concluding unacceptably high toxicity rate by the end of the trial based on toxicity data in the current stage is 0.62%. To date, there have been 0 local recurrences, 1 regional recurrence without local recurrence (8 months after SBRT completion, successfully salvaged with definitive chemoradiotherapy without additional toxicities), and 1 distant recurrence without local recurrence (6 months after SBRT in a patient with lung metastasis from colon adenocarcinoma).

CONCLUSION

Interim analysis of the DD3 trial suggests that for patients with central but not ultra-central lung tumors, an SBRT regimen of 45 Gy in 3 fractions warrants continued trial accrual and follow-up given no grade ≥3 toxicities or local recurrences in the early follow-up period among the first 17 patients enrolled.

In search of susceptibility genes for type 2 diabetes in West Africa: the design and results of the first phase of the AADM study

PURPOSE

The purpose of this study is to map type 2 diabetes susceptibility genes in West African ancestral populations of African-Americans, through an international collaboration between West African and US investigators.

DESIGN AND METHODS

Affected sib-pairs (ASP) along with unaffected spouse controls are being enrolled and examined in West Africa, with two sites established in Ghana (Accra and Kumasi) and three in Nigeria (Enugu, Ibadan, and Lagos). Eligible participants are invited to study clinics to obtain detailed epidemiologic, family, and medical history information. Blood samples are drawn from each participant to measure glucose, insulin, C-peptide, total cholesterol, LDL, HDL, triglycerides, albumin, creatinine, urea, uric acid, total calcium and to detect autoantibodies to glutamic acid decarboxylase (GAD). DNA is isolated from frozen white blood cells obtained from 20 ml of EDTA whole blood samples.

RESULTS

With full informed consent, 162 individuals from 78 families have been enrolled and examined since the Africa America Diabetes Mellitus (AADM) study began in June of 1997. Logistics of field examinations and specimen shipping have been successfully established. At the end of the third year of field activity (September 2000) the AADM study will have enrolled and performed comprehensive examination on 400 ASP with type 2 diabetes, for a minimum of 800 cases and 200 controls from Ghana and Nigeria. At the current participation rate, the goal of 400 sib-pairs and 200 controls will be met before the scheduled closing date.

CONCLUSIONS

The AADM study will create a comprehensive epidemiologic and genetic resource that will facilitate a powerful genome-wide search for West African susceptibility genes to type 2 diabetes.

Blood fluidity and coagulation phenomena in chronic arterial occlusive disease

Blood fluidity depends on a number of factors of which especially the deformability of erythrocytes is of importance. Investigations reported in this paper have revealed an interdependence between blood fluidity and coagulability of blood. They confirm the significance of maintaining red cells deformability if an adequate microcirculation is to be provided in patients with occlusive vascular disease. High doses of oral pentoxifylline are able to improve erythrocyte flow rates in patients with occlusive vascular disorder. This agent also decreases platelet hyper-reactivity, a factor of importance in arresting the arteriosclerotic progression. In addition the hypercoagulability existing in such patients is reduced and the fibrinolytic system stimulated by treatment with the drug.

Influence of pentoxifylline on erythrocyte deformability in peripheral occlusive arterial disease

Impaired red cell deformability has been found in patients suffering from chronic peripheral vascular disorders, the implication being that microcirculatory blood flow is hindered and tissue hypoxaemia is aggravated. Measurement of erythrocyte deformability by a standard filtration technique for whole blood was carried out in 40 young healthy persons, in 25 untreated patients with peripheral occlusive arterial disease and in 25 patients with matching vascular disease, before and after a 6-weeks' oral treatment with 400 mg pentoxifylline 4-times daily. The filtration rates were significantly lower in the patient groups compared to those of healthy volunteers. After the oral administration of pentoxifylline, a significant increase in filtration rates was observed pointing to an improvement in erythrocyte deformability. The findings suggest that by improving erythrocyte deformability pentoxifylline positively influences the microcirculatory blood fluidity, an important factor for efficient therapy in peripheral arterial occlusive disease.