Hemopoietic-specific Sf3b1-K700E knock-in mice display the splicing defect seen in human MDS but develop anemia without ring sideroblasts

Heterozygous somatic mutations affecting the spliceosome gene SF3B1 drive age-related clonal hematopoiesis, myelodysplastic syndromes (MDS) and other neoplasms. To study their role in such disorders, we generated knock-in mice with hematopoietic-specific expression of Sf3b1-K700E, the commonest type of SF3B1 mutation in MDS. Sf3b1K700E/+ animals had impaired erythropoiesis and progressive anemia without ringed sideroblasts, as well as reduced hematopoietic stem cell numbers and host-repopulating fitness. To understand the molecular basis of these observations, we analyzed global RNA splicing in Sf3b1K700E/+ hematopoietic cells. Aberrant splicing was associated with the usage of cryptic 3' splice and branchpoint sites, as described for human SF3B1 mutants. However, we found a little overlap between aberrantly spliced mRNAs in mouse versus human, suggesting that anemia may be a consequence of globally disrupted splicing. Furthermore, the murine orthologues of genes associated with ring sideroblasts in human MDS, including Abcb7 and Tmem14c, were not aberrantly spliced in Sf3b1K700E/+ mice. Our findings demonstrate that, despite significant differences in affected transcripts, there is overlap in the phenotypes associated with SF3B1-K700E between human and mouse. Future studies should focus on understanding the basis of these similarities and differences as a means of deciphering the consequences of spliceosome gene mutations in MDS.

SU-E-T-570: Improvement to the Histogram Analysis in Radiation Therapy (HART): An Open Source Software System for the Multi-Dimensional Dose- Volume Histogram Analysis in Digital Image Communication in Medicine - Radiation Therapy (DICOM-RT) Treatment Plans

PURPOSE

Histogram Analysis in Radiation Therapy (HART) is an efficient and accurate dose-volume histogram (DVH) computational tool in radiotherapy research. Several applications of the program have been presented previously (J Appl Clin Med Phys 11(1): 3013, 2010; Med Phys 38(6), p.3678, 2011) for the Radiation Therapy Oncology Group (RTOG) users. The program has been further developed to incorporate various types of DVH analysis features to support the research using DICOM-RT plans. The main objective of this work was to present the improvement and compatibility of the program for the DICOM-RT plans.

METHODS AND MATERIALS

MATLAB based codes were primarily designed to read and write a simpler HART format from the standard DICOM-RT data objects exported from the Xio treatment planning system (CMS Inc., St. Louis, MO). This format employed an optimal polynomial fitting technique to interpolate the co-ordinates of the contours in the regions-of-interest. The format was efficient for the (a) precise extraction of the cumulative DVH (cDVH) and spatial DVH (sDVH; x-,y-, and z-DVHs respectively) data- statistics, (b) universal-plan indices evaluation, (c) biological modeling based outcome analyses (BMOA), (d) radiobiological dose-response modeling, and (e) physical parameterization modules. The fundamental DVH statistics were validated using the DVH statistics extracted from the Computational Environment for Radiotherapy Research program.

RESULTS

HART offers various types of DVH computational functionalities, several plan evaluation and radiobiological outcome analysis modules in a user- friendly software package for the RTOG and DICOM-RT planners. The cDVH and BMOA modules were found to be the most applicable features for the global researchers.

CONCLUSIONS

HART is a novel and universal multi-dimensional DVH analysis tool for the radiation therapy research. We further expect to develop HART for the space-time DVH analysis and proton therapy applications. The software is available online (http://www2.uic.edu/∼apyaku1) for the radiotherapy research. This work was partially supported by NIH-NIDCD grant.

Hyperthermia and radiation therapy for locally advanced or recurrent breast cancer

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Background: Hyperthermia is a known radiation sensitizer. This retrospective series evaluates a single institutional experience with hyperthermia and radiotherapy (RT) for locally advanced/recurrent breast cancer, many referred for palliation. Methods: Records of 130 pts with locally advanced/recurrent breast cancers treated with hyperthermia and RT from 1991–2007 were reviewed. 40% had distant metastases. 168 different sites were irradiated to 16–76.4 Gy (median 50 Gy) with conventional fractions and treated with 1–11 hyperthermia sessions twice/wk (median 6). 58 pts required >1 hyperthermia field to cover tumor. Intratumoral temperature goal was >42.5°C for >45 min. Thermal equivalent dose (TED) was calculated for each treatment (min above 42.5 and 43°C). Results: Median and mean FU of alive patients was 20 and 32 mos, respectively. 27 pts were treated for locally advanced and 103 for recurrent cancer on the chest wall, nearby skin, or nodes. Treated sites were: intact breast (21%), chest wall/skin (66%), nodes (12%). Disease volume was microscopic in 11%, less than 3 cm in 11%, and greater than in 78%. Various concurrent chemotherapy regimens were given in 56%. 40% of treated sites had prior RT (median 50 Gy). CR was seen in 52% and CR/PR in 79% in pts with measurable tumor. 5 mastectomies were done, with no residual cancer in 1. Local control (LC) at last FU was obtained in 58% of treated sites. Type (primary vs recurrent), location (breast/chest wall/node), extent of disease (3 cm), or prior RT were not associated with LC. Improved LC was seen with increased RT dose, 36%, 52%, and 70% for 16–39.6 Gy, 40–50 Gy, and 50+ Gy, respectively. LC also improved with more minutes of hyperthermia - median of 238 min and 147 min TED 42.5°C & 43°C, respectively in pts with LC, and median of 180 min and 105 min TED 42.5°C and 43°C, respectively in pts without LC. All pts with microscopic disease are controlled. 16 pts (12%) are NED (mean 32 mos). Conclusions: Hyperthermia and RT improves local control and can palliate locally advanced or recurrent breast cancer, even in previously irradiated pts - a quality of life issue. Although the followup of this poor prognosis group is short, local control appears to be maintained to death for many pts. Pts with microscopic residual cancer after resection may benefit from the combination.

No significant financial relationships to disclose.

Re-irradiation and external hyperthermia in locally advanced, radiation recurrent, hormone refractory prostate cancer: a preliminary report

The purpose of this report is to present the preliminary results of re-irradiation and external hyperthermia in patients with locally advanced, previously irradiated, hormone refractory prostate cancer. Three consecutive patients with symptomatic, locally advanced, previously irradiated and hormone refractory prostate cancer were treated with further irradiation (30.6-50 Gy) and external hyperthermia (5-8 treatments). All patients had complete resolution of symptoms lasting for 12-24 months. Significant tumour shrinkage, including complete tumour response, was demonstrated by CT and endoscopy. In one case, at 2 years after re-treatment, there is continued tumour regression and bone regeneration in the pelvis. Two patients had local control of tumour, which continued until most recent follow-up at 12 months and more than 24 months, respectively. Another case developed local recurrence at 17 months. At most recent follow-up, no patient has experienced significant treatment-related side effects. In these patients with no other therapeutic alternatives, re-irradiation and hyperthermia can provide durable tumour response for more than a year, resulting in significant improvement in quality of life. Further clinical studies are warranted.

Adverse impact of multileaf collimator field shaping on lens dose in children with acute leukemia receiving cranial irradiation

PURPOSE

This study was designed to investigate the impact of multileaf collimator (MLC) on lens dose in children with leukemia undergoing cranial irradiation.

METHODS AND MATERIALS

This is a prospective study utilizing three common cranial irradiation techniques. Technique A uses a half-beam, nondivergent radiation field. Technique B has the anterior divergent field edge at the lateral bony canthus. Technique C is similar to B, but with a field collimator angle. Thermoluminescent dosimeter (TLD) lens dose measurements were obtained in children and phantom with all three techniques.

RESULTS

Seventeen children were studied. Lens dose measurements were obtained in 14 children with technique A using MLC and blocks. In 7 of 14 children, dose measurements were obtained with MLC only. One child was treated with technique B and 2 children were treated with C, with MLC +/- blocks. In all 3 techniques, with MLC alone, the lens dose increased by 64%, 119%, and 72%, respectively. Similar results were obtained in phantom.

CONCLUSION

This study demonstrates that independent of irradiation technique, additional custom blocking is required to maximally protect the lens with MLC shaped fields. This is due to the lack of conformity between MLC and the desired field edge at the lateral bony canthus.

Phase I/II trial of combined 131I anti-CEA monoclonal antibody and hyperthermia in patients with advanced colorectal adenocarcinoma

BACKGROUND

This pilot project was undertaken to evaluate the toxicity of and tumor response to combined 131I anti-carcinoembryonic antigen monoclonal antibody (131I anti-CEA RMoAb) and hyperthermia in patients with metastatic colorectal adenocarcinoma.

METHODS

Nine patients who had colorectal carcinoma with liver metastases were enrolled in this study. Intact 131I anti-CEA RMoAb was used (the specific antibody was IMMU-4, provided by Immunomedics, Inc., Morris Plains, NJ). During the diagnostic phase, dosimetry revealed that the tumor site received a higher radiation dose than the surrounding normal tissues in only six patients. These six, who were treated with radioimmunotherapy and hyperthermia, were the basis of this study. The first three patients were treated with 30 mCi/m2 of 131I anti-CEA RMoAb, and the next three received 60 mCi/m2. Pharmacokinetic clearance data were reported for all nine patients.

RESULTS

Thermometry data revealed an average T90 of 40.3 (+/- 1.4 degrees C) and T50 of 41.1 (+/- 1.2 degrees C). The average thermal dose equivalent at 42.5 degrees C was 34.5 (+/- 21.5) minutes. The average Tmin, Tmax, and Tmeam were 40 (+/- 1.2 degrees C), 42.4 (+/- 0.7 degrees C), and 41.1 (+/- 1.1 degrees C), respectively. The pharmacokinetic clearance data of antibody showed monoexponential plasma clearances in all patients except one, in whom a biexponential plasma clearance was observed. In general, similar plasma and whole-body clearances as well as similar urinary excretions were observed when diagnostic and therapeutic phases for each patient were compared. Two of the six patients showed a marked improvement in their symptoms; five patients showed a drop in carcinoembryonic antigen levels. A follow-up computed tomography scan one month after treatment showed no change in tumor volume in five patients; one patient showed a partial response. Three patients developed toxicity, two developed moderate thrombocytopenia (39,000 and 58,000), and the other patient developed hematoma resulting from the insertion of a catheter for thermometry.

CONCLUSIONS

It is feasible to combine hyperthermia and radiolabeled monoclonal antibodies, and the combination was well tolerated by these patients. The interaction between hyperthermia and low dose rate radioimmunotherapy is complex. Further studies are necessary to explore the use of this combined modality in the management of maligancies.

Effects of hyperthermia and iodine-131-labeled anticarcinoembryonic antigen monoclonal antibody on human tumor xenografts in nude mice

BACKGROUND

Many studies have demonstrated synergistic interaction between hyperthermia and radiation. This study was undertaken to determine whether hyperthermia could enhance the effect of radioimmunotherapy (RIT) in the treatment of human colon adenocarcinoma xenografts in nude mice.

METHODS

The experiments were conducted in two parts. During the first part of the study, preliminary information was obtained regarding the effect of various temperatures (41 degrees C, 42 degrees C, and 43 degrees C for 45 minutes) and iodine-131-labeled anticarcinoembryonic antigen (CEA) monoclonal antibodies (RMoAb) with administered activity ranging from 130 +/- 19 microCi to 546 +/- 19 microCi on tumor regrowth delay (TRD) and volume doubling time. This information was used in Part 2 of the study, which included four groups of mice: (1) a control group, (2) a group treated with hyperthermia, (3) a group treated with RMoAb, and (4) a group treated with a combination of RMoAb and hyperthermia.

RESULTS

Maximum and significantly increased TRD was observed in the group treated with RMoAb and hyperthermia (slope, 0.057) compared with the control group (slope, 0.322), the hyperthermia-treated group (slope, 0.302), and the group treated with RMoAb alone (slope, 0.098). The ratio of the slopes between the groups treated with RMoAb and those treated with RMoAb and hyperthermia was 1.72. No correlation was detected between the percent of antibody uptake in the tumor and tumor regression in the groups treated with heat and RMoAb and those treated with RMoAb alone.

CONCLUSIONS

The results of these experiments show that hyperthermia increased the effectiveness of iodine-131-labeled anti-CEA monoclonal antibodies against human colon carcinoma xenografts in nude mice. This study offers a rationale for combining hyperthermia and low-dose radiation produced from RIT in clinical practice.

Initial results for automated computational modeling of patient-specific electromagnetic hyperthermia

Developments in finite-difference time-domain (FD-TD) computational modeling of Maxwell's equations, super-computer technology, and computed tomography (CT) imagery open the possibility of accurate numerical simulation of electromagnetic (EM) wave interactions with specific, complex, biological tissue structures. One application of this technology is in the area of treatment planning for EM hyperthermia. In this paper, we report the first highly automated CT image segmentation and interpolation scheme applied to model patient-specific EM hyperthermia. This novel system is based on sophisticated tools from the artificial intelligence, computer vision, and computer graphics disciplines. It permits CT-based patient-specific hyperthermia models to be constructed without tedious manual contouring on digitizing pads or CRT screens. The system permits in principle near real-time assistance in hyperthermia treatment planning. We apply this system to interpret actual patient CT data, reconstructing a 3-D model of the human thigh from a collection of 29 serial CT images at 10 mm intervals. Then, using FD-TD, we obtain 2-D and 3-D models of EM hyperthermia of this thigh due to a waveguide applicator. We find that different results are obtained from the 2-D and 3-D models, and conclude that full 3-D tissue models are required for future clinical usage.