The Feasibility of Dose-Escalated Radiation Therapy for Glioblastoma Using Biological Image Guided Adaptive Radiotherapy (BIGART)

PURPOSE/OBJECTIVE(S)

Radiotherapy dose escalation (DE) for glioblastoma (GBM) has been an area of active research. We aimed to study the imaging changes within residual gross tumor volumes (GTV) through the course of concurrent chemo-radiotherapy (CCRT) using multiparametric magnetic resonance imaging (mpMRI). Diffusion, perfusion and chemical exchange saturation transfer (CEST) characteristics of the tumor and its microenvironment were investigated to identify a GTV subvolume potentially associated with radio resistance. We used biological image-guided adaptive radiotherapy (BIGART) to study the feasibility of DE to this GTV subvolume using either photon or proton beam therapy (PBT).

MATERIALS/METHODS

We prospectively identified GBM patients with >5cc residual tumor post-resection who were candidates for radical CCRT (60 Gy in 30 daily fractions over 6-weeks with concurrent temozolomide 75mg/m2 daily). We observed the imaging changes with serial mpMRI scans done at baseline, after 2, 4 and 6-weeks of CCRT. Regions of interest (ROIs) within the GTV associated with the following abnormal values at week 2 were identified: apparent diffusion coefficient (ADC): 750-1000 ×10-6 mm2/s; relative cerebral blood volume (rCBV): 1.75-6; and APT-w CEST signal intensity >1.79%. The overlap regions of these ROIs were defined as a novel biological target volume (BTV), identifying the potential area of maximal radioresistance. An in silico study was performed using a technology company's treatment planning system to evaluate the feasibility of planning adaptive treatment to the BTV to total dose of 75 Gy in 30 fractions. This is given in two phases: 30 Gy/15# to the whole PTV as per standard practice, followed by a simultaneous integrated boost (SIB) of 45 Gy/15 fractions while maintaining the dose to the rest of the of the PTV to 60 Gy. Either photons or PBT were used to keep doses to organs at risk (OARs) within standard clinical tolerances.

RESULTS

Nine patients were recruited for this analysis and a total of 27 mpMRI scans were studied. Median BTVs to GTVs ratio was 35% (range 22-47%). Volumetric-modulated arc (VMAT) photon and PBT adaptive plans for dose escalation to BTVs were created in all cases whilst maintaining OAR tolerances. Both VMAT and PBT provided acceptable target coverage with average BTV-PTV D98% of 73 Gy (range 71.5-73.8 Gy) and average D2% of 76 Gy (range 75.4-77 Gy) while effectively sparing OARs. Sharper dose gradient between DE-BTV and PTV was achieved with VMAT. PBT was particularly advantageous in minimizing the low-dose spillage outside the BTV.

CONCLUSION

We hereby propose a platform for adaptive radiotherapy to GBM tumors with biological-image guidance through the utilization of mpMRI to evaluate the tumor and its microenvironment during CCRT. We identified thresholds for tumor sub volumes showing the most resistant imaging features and created precise BTVs that allowed for dose escalation. PBT represents an additional useful tool for BIGART planning that will be investigated further in our ongoing work.

Abstract P5-01-01: Adding whole-body MRI to body CT scans when evaluating response to systemic anti-cancer therapies alters treatment decisions in metastatic breast cancer

Introduction

Accurate evaluation of disease extent and response to systemic anti-cancer therapy (SACT) is key to the clinical management of patients with metastatic breast cancer. By identifying disease distribution and response (particularly progression prior to symptomatic deterioration), imaging aids therapy choices and may maximise quality of life. Whole body MRI (WB-MRI) has increased accuracy for detecting liver and bone disease in breast cancer; however, its potential impact on patient management is largely unexplored. Thus, the purpose of this study was to evaluate the added value of WB-MRI with standard of care CT scans for clinical decision making in routine practice for patients with metastatic breast cancer.

Methods

All patients with metastatic breast cancer who had undergone WB-MRI between 1st April 2009 and 31st March 2016 were screened for this study. Those who had undergone a CT scan of the chest, abdomen and pelvis (CT-CAP) within 14 days of a WB-MRI date were eligible. Original radiology reports for the WB-MRI and CT-CAP were reviewed to establish the extent of reported disease and the SACT response assessment. Contemporaneous medical notes were reviewed to establish the impact of the paired imaging findings (and clinical review) with regard to therapy decisions per time point.

Results

210 pairs of WB-MRI and CT-CAP scans in 101 patients were eligible for analysis. The median age of the studied patients was 56 years (range 23 to 84 years). 46 examination pairs were baseline studies; 164 were undertaken for response assessments (1st line SACT = 46; 2nd line = 27; ≥3rd line = 58; no information = 33).

In 140 cases (66.7%) there were differences between the extent of disease reported by the WB-MRI and CT-CAP. Of these, 112 (80.0%) were due to the WB-MRI reporting additional sites of disease not evident on CT-CAP, mostly skeletal lesions. CT-CAP showed more disease in 10.0%, mostly lung lesions. 10.0% had some lesions evident only on WB-MRI and other lesions evident only on CT-CAP.

Of the 164 scan pairs performed for SACT response assessment, there were differences in the reported response to therapy in 46 cases (28.0%). 89.1% of disagreements were due to WB-MRI showing evidence of either disease progression (67.4%) or partial response (21.7%) that was reported as stable disease on CT-CAP.

Decisions to change SACT in response to disease progression reported by either/both imaging methods were made in 80 cases. Of these, treatment changes were made due to progression reported only on WB-MRI in 23 (28.8%) cases.

Discussion

This is a retrospective analysis of the real world use of WB-MRI and CT-CAP in the clinical practice of metastatic breast cancer, evaluating their impact on clinical care on a per time point basis. WB-MRI identified additional sites of disease (mostly bone) in over half of patients, which affected SACT decisions in a significant proportion of cases. In many cases, SACT changes would not have been made at the same time point without WB-MRI information. Further research is required to test the hypothesis that earlier identification of disease progression by WB-MRI leads to improved quality of life and patient outcomes.

Citation Format: Kosmin M, Makris A, Joshi PV, Ah-See M-L, Padhani AR. Adding whole-body MRI to body CT scans when evaluating response to systemic anti-cancer therapies alters treatment decisions in metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-01-01.

Abstract P4-21-36: Splenic enlargement and bone marrow hyperplasia in patients receiving trastuzumab-emtansine for metastatic breast cancer

Introduction

Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate used for treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. An association between T-DM1 and splenic enlargement was noted anecdotally on sequential whole-body MRI (WB-MRI) examinations. A retrospective analysis of WB-MRI examinations of patients on T-DM1 was undertaken to investigate the hypothesis that an increase in splenic volume is due to either a generalised hyperplasia of the bone marrow and reticulo-endothelial system and/or an increase in portal venous pressure.

Methods

12 patients underwent 29 serial WB-MRIs before and during T-DM1 therapy. Splenic volume, portal vein diameter, bone marrow muscle-normalised signal intensity (nSI), water diffusivity (apparent diffusion coefficient, ADC) and fat fraction were measured. Changes in splenic volume were analysed, and correlations between the measured variables were obtained.

Results

An increase in splenic volume was observed in 92% of patients. Mean splenic volume increased from 144cm3 (95%CI 110-177cm3) to 209cm3 (95%CI 161-257cm3) on T-DM1 therapy (p=0.006). Increase in splenic volume correlated with treatment duration (r2=0.71). Increase in normal bone marrow signal was seen (nSI 3.5 to 4.8, p=0.12), along with a decrease in fat fraction (64.3% to 57.3%, p=0.12), and reduced ADC (655µm2/s to 543µm2/s, p=0.11). No consistent changes to portal vein diameter were seen.

Discussion

An increase in splenic volume was consistently observed in patients on T-DM1 therapy. This was unrelated to portal vein changes but correlated with bone marrow hyperplasia. Caution should be applied when assessing metastatic disease in bone to avoid incorrectly attributing T-DM1-related changes in normal bone marrow to disease progression.

Citation Format: Kosmin M, Makris A, Jawad N, Miles D, Padhani AR. Splenic enlargement and bone marrow hyperplasia in patients receiving trastuzumab-emtansine for metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-36.

A systematic review of the prognostic value of lymph node ratio, number of positive nodes and total nodes examined in pancreatic ductal adenocarcinoma

BACKGROUND Pancreatic ductal adenocarcinoma is the most common pancreatic cancer. Five-year overall survival is currently 3.3-6.0%. The aim of this review was to evaluate the prognostic value of lymph node ratio, number of positive nodes and total nodes examined on overall survival rate following pancreatic resection. MATERIALS AND METHODS A literature search was conducted of MEDLINE, EMBASE, the Cochrane Library and Central Register of Controlled Trials and the Cochrane Database of Systematic Review databases, from January 1996 to January 2016. RESULTS Overall, 19 studies including 4,883 patients examined the relationship between lymph node ratio and overall survival. A high lymph node ratio was associated with decreased overall survival in 17 studies. A total of 12 studies examined the relationship between the number of positive nodes and overall survival, and 11 studies revealed that an increase in the number of positive nodes was associated with decreased overall survival. In 15 studies examining the relationship between the total nodes examined and overall survival, there was no association with overall survival in 12 studies. CONCLUSIONS Lymph node ratio and number of positive nodes are factors associated with overall survival in pancreatic ductal adenocarcinoma, but not total nodes examined.

Case-control studies show that a non-conservative amino-acid change from a glutamine to arginine in the P2RX7 purinergic receptor protein is associated with both bipolar- and unipolar-affective disorders

Three linkage studies of bipolar disorder have implicated chromosome 12q24.3 with lod scores of over 3.0 and several other linkage studies have found lods between 2 and 3. Fine mapping within the original chromosomal linkage regions has identified several loci that show association with bipolar disorder. One of these is the P2RX7 gene encoding a central nervous system-expressed purinergic receptor. A non-synonymous single nucleotide polymorphism, rs2230912 (P2RX7-E13A, G allele) and a microsatellite marker NBG6 were both previously found to be associated with bipolar disorder (P=0.00071 and 0.008, respectively). rs2230912 has also been found to show association with unipolar depression. The effect of the polymorphism is non-conservative and results in a glutamine to arginine change (Gln460Arg), which is likely to affect P2RX7 dimerization and protein-protein interactions. We have confirmed the allelic associations between bipolar disorder and the markers rs2230912 (P2RX7-E13A, G allele, P=0.043) and NBG6 (P=0.010) in a London-based sample of 604 bipolar cases and 560 controls. When we combined these data with the published case-control studies of P2RX7 and mood disorder (3586 individuals) the association between rs2230912 (Gln460Arg) and affective disorders became more robust (P=0.002). The increase in Gln460Arg was confined to heterozygotes rather than homozygotes suggesting a dominant effect (odds ratio 1.302, CI=1.129-1.503). Although further research is needed to prove that the Gln460Arg change has an aetiological role, it is so far the most convincing mutation to have been found with a role for increasing susceptibility to bipolar and genetically related unipolar disorders.

The cost-effectiveness of autologous transfusion revisited: implications of an increased risk of bacterial infection with allogeneic transfusion

BACKGROUND

Previous analyses have found autologous transfusion to be very expensive but have not considered avoidance of postoperative bacterial infections as one of its benefits.

STUDY DESIGN AND METHODS

A cost-utility analysis using a Markov cohort simulation model compared autologous blood transfusion to allogeneic transfusion in a hypothetical cohort of patients undergoing elective total hip replacement with respect to discounted quality-adjusted life years (QALYs) and health-care system costs.

RESULTS

Assuming a base case rate of serious infection of 3.7 percent, a relative risk of infection of 1.85, and additional costs of $12,980 per infection, autologous transfusion has a cost-effectiveness of $2,470 per QALY. If the relative risk of bacterial infection following allogeneic transfusion exceeds 1.1, the cost-effectiveness of autologous transfusion is less than $50,000 per QALY and if the relative risk exceeds 2.4, autologous transfusion is dominant, resulting in both lower costs and greater QALYs. If there were no increased risk of transfusion, the cost-effectiveness of autologous transfusion would be $3,400,000 per QALY.

CONCLUSIONS

If there is only a modest increase in the risk of bacterial infection following allogeneic transfusion, autologous transfusion would result in improved outcomes at a cost of less than $50,000 per QALY. Autologous transfusion would be dominant above a relative risk of infection that is within the range of values observed in randomized controlled trials. However, if there is no increased risk of bacterial infection, autologous transfusion would be a very expensive strategy. Until more definitive data are available on the magnitude and costs of this risk, we advise against prematurely closing the debate about the cost-effectiveness of autologous transfusion.

Concurrent presentation of erythrocytic and megakaryocytic aplasia

A case of a patient presenting with idiopathic concurrent erythrocytic and megakaryocytic aplasia is reported. The patient's response to immunosuppressive therapy and her bone marrow pathology clearly suggest an immune mechanism. Based on the lack of suppression of erythroid colony growth, several mechanisms are postulated. Well-established molecular and genetic evidence, along with clinical observations, suggests that a relationship exists between the erythrocytic and megakaryocytic cell lines. This may be related to a common bipotential stem cell or common cell surface markers. This case provides strong clinical evidence to support this relationship.

Hemolytic anemia associated with lead poisoning from shotgun pellets and the response to Succimer treatment

Symptomatic lead poisoning with severe hemolytic anemia was observed in a patient with retained shot gun pellets. Surgical resection of the retained pellets and the use of a newer chelating agent, Succimer (2,3-dimercaptosuccinic acid) successfully lowered blood lead level. Hemolytic anemia was associated with deficient erythrocyte pyrimidine 5'-nucleotidase, and lowering of the lead level corrected the deficiency, suggesting that the enzyme deficiency is responsible for the hemolysis associated with lead poisoning. This case illustrates that retained lead pellets from shotgun wounds can cause severe lead poisoning.

Neonatal thrombosis with anticardiolipin antibody in baby and mother

The anticardiolipin antibody is associated with increased risk of thrombosis, which is manifested with various clinical presentations, including vascular thrombosis, recurrent fetal wastage, and neurologic defects. We report a case of neonatal thrombosis occurring in the renal vein and inferior vena cava associated with moderate positive anticardiolipin antibody titer in the baby while the maternal serum showed even stronger anticardiolipin antibody of immunoglobulin G class. Subsequent follow-up over the 4 months postpartum period showed a disappearance of the antibody in the baby, whereas the mother's antibody persisted. This case illustrates the fact that the maternal anticardiolipin antibody can be transferred to the fetus and may be a risk factor for thrombosis in the neonates. Anticardiolipin antibody syndrome should be considered in the differential diagnosis of neonatal thrombosis.

Increased preoperative collection of autologous blood with recombinant human erythropoietin therapy

To study whether the administration of recombinant human erythropoietin increases the amount of autologous blood that can be collected before surgery, we conducted a randomized, controlled trial of erythropoietin in 47 adults scheduled for elective orthopedic procedures. The patients received either erythropoietin (600 units per kilogram of body weight) or placebo intravenously twice a week for 21 days, during which time up to 6 units of blood was collected. Patients were excluded from donation when their hematocrit values were less than 34 percent. All patients received iron sulfate (325 mg orally three times daily). The mean number of units collected per patient (+/- SE) was 5.4 +/- 0.2 for the erythropoietin group and 4.1 +/- 0.2 for the placebo group. The mean red-cell volume donated by the patients who received erythropoietin was 41 percent greater than that donated by the patients who received placebo (961 vs. 683 ml, P less than 0.05). Only 1 of the 23 patients treated with erythropoietin was unable to donate greater than or equal to 4 units (4 percent) as compared with 7 of the 24 patients who received placebo (29 percent). No adverse effects were attributed to erythropoietin. We conclude that recombinant human erythropoietin increases the ability of patients about to undergo elective surgery to donate autologous blood.

Natural history of acquired immunodeficiency syndrome in hemophilic patients

During the 5-year period from 1981 to 1985, we have observed 8 cases of acquired immunodeficiency syndrome (AIDS) among our 85 patients with hemophilia A. Thus, the prevalence of AIDS with hemophilia A is 9.4% in our patient population. By utilizing stored serum or plasma samples dating back to 1978, antibody against HTLV-III was detected in all 8 cases with AIDS. Based on the time interval from the appearance of antibody to HTLV-III to the diagnosis of AIDS in these patients, the incubation period ranged from 27 months to 60 months, with a median of 36 months. Before the diagnosis of full-blown AIDS, all patients exhibited a variety of prodromal manifestations of non-specific nature, including weight loss, oral candidiasis, unexplained non-productive chronic cough, generalized lymphadenopathy, and thrombocytopenia lasting several months to several years. Serial T-lymphocyte subset studies were available in some patients during the HTLV-III seropositive period and showed progressive lymphopenia, depletion of T4 cells with an average absolute count of 94 +/- 128 per mm3 (mean +/- 1 S.D.), and a markedly reversed T4/T8 ratio of 0.26 +/- 0.19 (mean +/- 1 S.D.). These findings suggest that the incubation period of AIDS is considerably long and that prospective study of serial immunologic markers and HTLV-III markers may be warranted in hemophilic patients at risk.

Clinical trial of a new disposable bleeding-time device

A new disposable bleeding time device (Hemalet) was tested in 20 normal individuals and 11 patients with various bleeding disorders. The results were compared with those of Simplate II. The mean bleeding time for normal individuals was 5.4 +/- 1.5 (mean +/- 1 SD) minutes by Hemalet and 5.8 +/- 1.4 (mean +/- 1 SD) minutes by Simplate II, with good correlation between the results by the two devices (r = 0.81). The bleeding time in patients with various bleeding disorders were also comparably prolonged between the two devices. The new disposable bleeding time device with a disposable blade has quick release (penetration) into skin and retraction, and offers an alternative means of a bleeding time test.