Phase I Trial of Total Marrow and Lymphoid Irradiation Transplantation Conditioning in Patients with Relapsed/Refractory Acute Leukemia.

Current conditioning regimens provide insufficient disease control in relapsed/refractory acute leukemia patients undergoing hematopoietic stem cell transplantation (HSCT) with active disease. Intensification of chemotherapy and/or total body irradiation (TBI) is not feasible because of excessive toxicity. Total marrow and lymphoid irradiation (TMLI) allows for precise delivery and increased intensity treatment via sculpting radiation to sites with high disease burden or high risk for disease involvement, while sparing normal tissue. We conducted a phase I trial in 51 patients (age range, 16 to 57 years) with relapsed/refractory acute leukemia undergoing HSCT (matched related, matched unrelated, or 1-allele mismatched unrelated) with active disease, combining escalating doses of TMLI (range, 1200 to 2000 cGy) with cyclophosphamide (CY) and etoposide (VP16). The maximum tolerated dose was declared at 2000 cGy, as TMLI simulation studies indicated that >2000 cGy might deliver doses toxic for normal organs at or exceeding those delivered by standard TBI. The post-transplantation nonrelapse mortality (NRM) rate was only 3.9% (95% confidence interval [CI], .7 to 12.0) at day +100 and 8.1% (95% CI, 2.5 to 18.0) at 1 year. The cumulative incidence of grades II to IV acute graft-versus-host disease (GVHD) was 43.1% (95% CI, 29.2 to 56.3) and for grade III and IV, it was 13.7% (95% CI, 6.9 to 27.3). The day +30 complete remission rate for all patients was 88% and was 100% for those treated at 2000 cGy. The overall 1-year survival was 55.5% (95% CI, 40.7 to 68.1). The TMLI/CY/VP16 conditioning regimen is well tolerated at TMLI doses up to 2000 cGy with a low 100-day and 1-year NRM rate and no increased risk of GVHD with higher doses of radiation.

Clinical outcomes of patients treated with a second course of stereotactic radiosurgery for locally or regionally recurrent brain metastases after prior stereotactic radiosurgery.

Patients with metastatic disease are living longer and may be confronted with locally or regionally recurrent brain metastases (BM) after prior stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT). This study analyzes outcomes in patients without prior whole brain radiotherapy (WBRT) who were treated with a second course of SRS/FSRT for locally or regionally recurrent BM. We identified 32 patients at our institution who were treated with a second course of SRS/FSRT after initial SRS/FSRT for newly diagnosed BM. We report clinical outcomes including local control, survival, and toxicities. Control rates and survival were calculated using Kaplan-Meier analysis and the multivariate proportional hazards model. The Kaplan-Meier estimate of local control at 6 months was 77 % for targets treated by a second course of SRS/FSRT with 11/71 (15 %) targets experiencing local failure. Multivariate analysis shows that upon re-treatment, local recurrences were more likely to fail than regional recurrences (OR 8.8, p = 0.02). Median survival for all patients from first SRS/FSRT was 14.6 months (5.3-72.2 months) and 7.9 months (0.7-61.1 months) from second SRS/FSRT. Thirty-eight percent of patients ultimately received WBRT as salvage therapy after the second SRS/FSRT. Seventy-one percent of patients died without active neurologic symptoms. The present study demonstrates that the majority of patients who progress after SRS/FSRT for newly diagnosed BM are candidates for salvage SRS/FSRT. By reserving WBRT for later salvage, we believe that a significant proportion of patients can avoid WBRT all together, thus putting fewer patients at risk for neurocognitive toxicity.

An examination of nationwide trends in accelerated partial breast irradiation - The replacement of breast brachytherapy with intraoperative radiotherapy and external beam radiation.

PURPOSE: To examine recent modality utilization trends in accelerated partial breast irradiation (APBI) in the National Cancer Database (NCDB) based on the American Society for Radiation Oncology (ASTRO) guidelines. MATERIALS AND METHODS: A total of 58,194 patients treated with APBI were identified. Patients were segregated by APBI modality (brachytherapy, external beam radiotherapy [EBRT], and intraoperative radiotherapy ([IORT]). These patients were then further classified by suitability to receive APBI based on ASTRO guidelines. Temporal trends in utilization were evaluated using linear regression. Logistic regression was applied to study factors contributing to APBI modality choice and treatment within the ASTRO suitability groups. RESULTS: Patients treated with brachytherapy, EBRT, and IORT comprised 70.5%, 17.5%, and 12.0% of patients treated with APBI. From 2008 to 2017, total APBI cases remained relatively stable (-54.1 cases/year, p = 0.161) while brachytherapy cases decreased by 258.7 cases/year (p < 0.001). EBRT and IORT increased by 51.5 cases/year (p = 0.019) and 153.1 cases/year (p < 0.001), respectively. 40.0% of patients treated with APBI were classified as "suitable", which increased from 2010 to 2017 from 35.3% to 45.3% (slope = 1.51%/year, r2 = 0.61, p = 0.022). In comparison, 36.0% (36.1% in 2010 to 33.1% in 2017) of patients were classified as "cautionary" (slope = -0.33%/year, r2 = 0.63, p = 0.019) and 23.9% (28.6% in 2010 to 21.6% in 2017) of patients were classified as "unsuitable" (slope = -1.18%/year, r2 = 0.67, p = 0.012). CONCLUSIONS: While overall APBI utilization has remained stable since 2008, this has been accompanied by a decline in brachytherapy and a rise in IORT. The causes of these trends should be the topic of future research.

Total Marrow and Lymphoid Irradiation with Post-Transplantation Cyclophosphamide for Patients with AML in Remission.

Graft-versus-host disease (GVHD) has remained the main cause of post-transplantation mortality and morbidity after allogeneic hematopoietic cell transplantation (alloHCT), adding significant economic burden and affecting quality of life. It would be desirable to reduce the rate of GVHD among patients in complete remission (CR) without increasing the risk of relapse. In this study, we have tested a novel conditioning regimen of total marrow and lymphoid irradiation (TMLI) at 2000 cGy, together with post-transplantation cyclophosphamide (PTCy) for patients with acute myeloid leukemia in first or second CR, to attenuate the risk of chronic GVHD by using PTCy, while using escalated targeted radiation conditioning before allografting to offset the possible increased risk of relapse. The primary objective was to evaluate the safety/feasibility of combining a TMLI transplantation conditioning regimen with a PTCy-based GVHD prophylaxis strategy, through the assessment of adverse events in terms of type, frequency, severity, attribution, time course, duration, and complications, including acute GVHD, infection, and delayed neutrophil/platelet engraftment. Secondary objectives included estimation of non-relapse mortality (NRM), overall survival (OS), relapse-free survival, acute and chronic GVHD, and GVHD-relapse-free survival (GRFS). A patient safety lead-in was first conducted to ensure there were no unexpected toxicities and was expanded on the basis of lack of dose-limiting toxicities. The patient safety lead-in segment followed 3 + 3 dose expansion/(de-)escalation rules based on observed toxicity through day 30; the starting dose of TMLI was 2000 cGy, and a de-escalation to 1800 cGy was considered. After the safety lead-in segment, an expansion cohort of up to 12 additional patients was to be studied. TMLI was administered on days -4 to 0, delivered in 200 cGy fractions twice daily. The radiation dose delivered to the liver and brain was kept at 1200 cGy. Cyclophosphamide was given on days 3 and 4 after alloHCT, 50 mg/kg each day for GVHD prevention; tacrolimus was given until day 90 and then tapered. Among 18 patients with a median age of 40 years (range 19-56), the highest grade toxicities were grade 2 Bearman bladder toxicity and stomatitis. No grade 3 or 4 Bearman toxicities or toxicity-related deaths were observed. The cumulative incidence of acute GVHD grade 2 to 4 and moderate-to-severe chronic GVHD were 11.1% and 11.9%, respectively. At a median follow up of 24.5 months, two-year estimates of OS and relapse-free survival were 86.7% and 83.3%, respectively. Disease relapse at 2 years was 16.7%. The estimates of NRM at 2 years was 0%. The GVHD/GRFS rate at 2 years was 59.3% (95% confidence interval, 28.8-80.3). This chemotherapy-free conditioning regimen, together with PTCy and tacrolimus, is safe, with no NRM. Preliminary results suggest an improved GRFS rate.

Radiation-Related Toxicities Using Organ Sparing Total Marrow Irradiation Transplant Conditioning Regimens.

PURPOSE: Toxicities after organ sparing myeloablative total marrow irradiation (TMI) conditioning regimens have not been well characterized. The purpose of this study is to report pulmonary, renal, thyroid, and cataract toxicities from a prospective trial monitoring patients up to 8 years after TMI. METHODS AND MATERIALS: A total of 142 patients with primarily multiple myeloma or acute leukemia undergoing hematopoietic cell transplantation were evaluated. Follow-up included pulmonary function tests, serum creatinine, glomerular filtration rate, thyroid panel, and ophthalmologic examinations performed at 100 days, 6 months, and annually. Median TMI dose was 14 Gy (10-19 Gy) delivered at 1.5 to 2.0 Gy twice per day at a dose-rate of 200 cGy/min. RESULTS: Median age was 52 years (range 9-70). Median follow-up (range) for all patients was 2 years (0-8) and for patients alive at the time of last follow-up (n = 50), 5.5 years (0-8). Mean organ doses in Gy were lung 7.0, kidneys 7.1, thyroid 6.7, and lens 2.8. The crude incidence of radiation pneumonitis (RP) was 1 of 142 (0.7%). The cumulative incidence of infection and RP (I/RP) was 22.7% at 2 years post-TMI. Mean lung dose ≤8 Gy predicted for significantly lower rates of I/RP (2-year cumulative incidence 20.8% vs 31.8%, P = .012). No radiation-induced renal toxicity was noted. Hypothyroidism occurred in 6.0% and cataract formation in 7.0% of patients. CONCLUSIONS: TMI delivered with intensity modulated radiation therapy results in lower organ doses and was associated with fewer toxicities compared with historical cohorts treated with conventional total body irradiation. Keeping the mean lung dose to 8 Gy or less was associated with lower pulmonary complications. Further evaluation in clinical trials of intensity modulated radiation therapy to deliver TMI, total marrow and lymphoid irradiation, and organ sparing conformal total body irradiation is warranted.

Pitch, roll, and yaw variations in patient positioning.

PURPOSE: To use pretreatment megavoltage-computed tomography (MVCT) scans to evaluate positioning variations in pitch, roll, and yaw for patients treated with helical tomotherapy. METHODS AND MATERIALS: Twenty prostate and 15 head-and-neck cancer patients were selected. Pretreatment MVCT scans were performed before every treatment fraction and automatically registered to planning kilovoltage CT (KVCT) scans by bony landmarks. Image registration data were used to adjust patient setups before treatment. Corrections for pitch, roll, and yaw were recorded after bone registration, and data from fractions 1-5 and 16-20 were used to analyze mean rotational corrections. RESULTS: For prostate patients, the means and standard deviations (in degrees) for pitch, roll, and yaw corrections were -0.60 +/- 1.42, 0.66 +/- 1.22, and -0.33 +/- 0.83. In head-and-neck patients, the means and standard deviations (in degrees) were -0.24 +/- 1.19, -0.12 +/- 1.53, and 0.25 +/- 1.42 for pitch, roll, and yaw, respectively. No significant difference in rotational variations was observed between Weeks 1 and 4 of treatment. Head-and-neck patients had significantly smaller pitch variation, but significantly larger yaw variation, than prostate patients. No difference was found in roll corrections between the two groups. Overall, 96.6% of the rotational corrections were less than 4 degrees. CONCLUSIONS: The initial rotational setup errors for prostate and head-and-neck patients were all small in magnitude, statistically significant, but did not vary considerably during the course of radiotherapy. The data are relevant to couch hardware design for correcting rotational setup variations. There should be no theoretical difference between these data and data collected using cone beam KVCT on conventional linacs.

Dose escalation of total marrow irradiation with concurrent chemotherapy in patients with advanced acute leukemia undergoing allogeneic hematopoietic cell transplantation.

PURPOSE: We have demonstrated that toxicities are acceptable with total marrow irradiation (TMI) at 16 Gy without chemotherapy or TMI at 12 Gy and the reduced intensity regimen of fludarabine/melphalan in patients undergoing hematopoietic cell transplantation (HCT). This article reports results of a study of TMI combined with higher intensity chemotherapy regimens in 2 phase I trials in patients with advanced acute myelogenous leukemia or acute lymphoblastic leukemia (AML/ALL) who would do poorly on standard intent-to-cure HCT regimens. METHODS AND MATERIALS: Trial 1 consisted of TMI on Days -10 to -6, etoposide (VP16) on Day -5 (60 mg/kg), and cyclophosphamide (CY) on Day -3 (100 mg/kg). TMI dose was 12 (n=3 patients), 13.5 (n=3 patients), and 15 (n=6 patients) Gy at 1.5 Gy twice daily. Trial 2 consisted of busulfan (BU) on Days -12 to -8 (800 µM min), TMI on Days -8 to -4, and VP16 on Day -3 (30 mg/kg). TMI dose was 12 (n=18) and 13.5 (n=2) Gy at 1.5 Gy twice daily. RESULTS: Trial 1 had 12 patients with a median age of 33 years. Six patients had induction failures (IF), and 6 had first relapses (1RL), 9 with leukemia blast involvement of bone marrow ranging from 10%-98%, 5 with circulating blasts (24%-85%), and 2 with chloromas. No dose-limiting toxicities were observed. Eleven patients achieved complete remission at Day 30. With a median follow-up of 14.75 months, 5 patients remained in complete remission from 13.5-37.7 months. Trial 2 had 20 patients with a median age of 41 years. Thirteen patients had IF, and 5 had 1RL, 2 in second relapse, 19 with marrow blasts (3%-100%) and 13 with peripheral blasts (6%-63%). Grade 4 dose-limiting toxicities were seen at 13.5 Gy (stomatitis and hepatotoxicity). Stomatitis was the most frequent toxicity in both trials. CONCLUSIONS: TMI dose escalation to 15 Gy is possible when combined with CY/VP16 and is associated with acceptable toxicities and encouraging outcomes. TMI dose escalation is not possible with BU/VP16 due to dose-limiting toxicities. Future efforts will focus on whether further dose escalation with CY/VP16 is safe, with the goal of improving disease control in this high-risk population.

Suberoylanilide hydroxamic acid induces hypersensitivity to radiation therapy in acute myelogenous leukemia cells expressing constitutively active FLT3 mutants.

Histone deacetylase inhibitors (HDIs) have shown promise as candidate radiosensitizer for many types of cancers. However, the mechanisms of action are not well understood, and whether they could have clinical impact on radiotherapy for leukemia is unclear. In this study, we demonstrate that suberoylanilide hydroxamic acid (SAHA) can increase radiosensitivity of acute myeloid leukemia (AML) cells through posttranslational modification of Rad51 protein responses and selective inhibition of the homology-directed repair (HDR) pathway. Our data also showed that AML cells with mutant, constitutively active FMS-like tyrosine kinase-3 (FLT3) were more radiation sensitive, caused by compromised non-homologous end joining (NHEJ) repair. Furthermore, SAHA-induced radiosensitization were enhanced in AML cells with expression of these FLT3 mutants. The results of this study suggest that SAHA, a recently approved HDI in clinical trials, may act as a candidate component for novel conditioning regimens to improve efficacy for AML patients undergoing radiotherapy and chemotherapy.

Suberoylanilide hydroxamic acid as a radiosensitizer through modulation of RAD51 protein and inhibition of homology-directed repair in multiple myeloma.

Histone deacetylase inhibitors (HDI) have shown promise as candidate radiosensitizers for many types of cancers. However, the mechanisms of action are not well understood, and whether they could sensitize multiple myeloma (MM) to radiation therapy is unclear. In this study, we show that suberoylanilide hydroxamic acid (SAHA) at low concentrations has minimal cytotoxic effects, yet can significantly increase radiosensitivity of MM cells. SAHA seems to block RAD51 protein response to ionizing radiation, consistent with an inhibitory effect on the formation of RAD51 focus in irradiated MM cells. These effects of SAHA on RAD51 focus are independent of cell-cycle distribution changes. Furthermore, we show that SAHA selectively inhibits the homology-directed repair (HDR) pathway. The results of this study suggest that SAHA, a recently approved HDI in clinical trials for malignancies, at lower concentrations may act as a radiosensitizer via disruption of the RAD51-dependent HDR pathway.

Low-dose valproic acid enhances radiosensitivity of prostate cancer through acetylated p53-dependent modulation of mitochondrial membrane potential and apoptosis.

Histone deacetylase inhibitors (HDI) have shown promise as candidate radiosensitizers for many types of cancers, including prostate cancer. However, the mechanisms of action are not well understood. In this study, we show in prostate cancer cells that valproic acid (VPA) at low concentrations has minimal cytotoxic effects yet can significantly increase radiation-induced apoptosis. VPA seems to stabilize a specific acetyl modification (lysine 120) of the p53 tumor suppressor protein, resulting in an increase in its proapoptotic function at the mitochondrial membrane. These effects of VPA are independent of any action of the p53 protein as a transcription factor in the nucleus, since these effects were also observed in native and engineered prostate cancer cells containing mutant forms of p53 protein having no transcription factor activity. Transcription levels of p53-related or Bcl-2 family member proapoptotic proteins were not affected by VPA exposure. The results of this study suggest that, in addition to nuclear-based pathways previously reported, HDIs may also result in radiosensitization at lower concentrations via a specific p53 acetylation and its mitochondrial-based pathway(s).

Resection followed by stereotactic radiosurgery to resection cavity for intracranial metastases.

PURPOSE: In patients who undergo resection of central nervous system metastases, whole brain radiotherapy (WBRT) is added to reduce the rates of recurrence and neurologic death. However, the risk of late neurotoxicity has led many patients to decline WBRT. We offered adjuvant stereotactic radiosurgery (SRS) or stereotactic radiotherapy (SRT) as an alternative to select patients with resected brain metastases. METHODS AND MATERIALS: We performed a retrospective review of patients who underwent brain metastasis resection followed by SRS/SRT. WBRT was administered only as salvage treatment. Patients had one to four brain metastases. The dose was 15-18 Gy for SRS and 22-27.5 Gy in four to six fractions for SRT. Target margins were typically expanded by 1 mm for rigid immobilization and 3 mm for mask immobilization. SRS/SRT involved the use of linear accelerator radiosurgery using the IMRT 21EX or Helical Tomotherapy unit. RESULTS: Between December 1999 and January 2007, 30 patients diagnosed with intracranial metastases were treated with resection followed by SRS or SRT to the resection cavity. Of the 30 patients, 4 (13.3%) developed recurrence in the resection cavity, and 19 (63%) developed recurrences in new intracranial sites. The actuarial 12-month survival rate was 82% for local recurrence-free survival, 31% for freedom from new brain metastases, 67% for neurologic deficit-free survival, and 51% for overall survival. Salvage WBRT was performed in 14 (47%) of the 30 patients. CONCLUSION: Our results suggest that for patients with newly diagnosed brain metastases treated with surgical resection, postoperative SRS/SRT to the resection cavity is a feasible option. WBRT can be reserved as salvage treatment with acceptable neurologic deficit-free survival.

HDAC inhibitor, valproic acid, induces p53-dependent radiosensitization of colon cancer cells.

Agents that inhibit histone deacetylases (HDAC inhibitors) have been shown to enhance radiation response. The aim of this study was to evaluate the effects of low, minimally cytotoxic concentrations of the HDAC inhibitor, valproic acid (VPA), on radiation response of colorectal cancer cells. Cell lines LS174T and an isogenic pair of HCT116, which differed only for the presence of wild-type p53, were exposed to ionizing radiation (IR) alone, VPA alone, or the combination. Clonogenic survival, gamma-H2AX induction, apoptosis, changes in mitochondrial membrane potential, and mitochondrial levels of p53 and Bcl-2 family proteins were assessed. In vivo studies monitored tumor growth suppression after therapy in mice bearing HCT116/p53(+/+) and HCT116/p53(-/-) tumor xenografts. VPA led to radiosensitization, which was dependent on p53 status. A decrease in clonogenic survival, an increase in apoptosis, and an increase in levels of gamma-H2AX were observed after VPA+IR, compared to IR alone, in wild-type p53 cells (LS174T and HCT116/p53(+/+)), as opposed to p53 null cells (HCT116/p53(-/-)). Exposure to VPA resulted in enhancement of IR-induced mitochondrial localizations of Bax and Bcl-xL, mitochondrial membrane potential, and cytochrome c release only in wild-type p53 cell lines. VPA also enhanced tumor growth suppression after IR only in wild-type p53 xenografts. These data suggest that VPA may have an important role in enhancing radiotherapy response in colorectal cancer, particularly in tumors with the wild-type p53 genotype.

Development of an in vitro chemo-radiation response assay for cervical carcinoma.

PURPOSE: To determine if synergistic effects of radiation (RT) and chemotherapy (chemo) on human cervical carcinoma cell lines and fresh tumor explants could be determined using an in vitro assay. EXPERIMENTAL DESIGN: In vitro radiation response was determined for 4 cell lines and 26 fresh tumor explants in an agar-based assay. Cells were exposed to increasing doses of RT with or without cisplatin (CDDP), carmustine (BCNU), buthionine sulfoximine (BSO), or paclitaxel (Tax). Cell suspensions were cultured for 5 days, with [(3)H]thymidine added on day 3 and proliferation was measured. Results were reported as the fraction of proliferation compared to control (FC). For each combination of irradiation and drug, synergy was tested using the Chou analysis, where a combination index (CI) <1 indicated synergistic interaction. In simple correlation analysis, an R value of >0.7 indicated cross-resistance. RESULTS: RT dose-dependent proliferation inhibition was observed for 2 of the 4 cell lines, and for all but 1 of the fresh specimens. Significant heterogeneity of tumor response to RT was seen. Four specimens that were 1 standard deviation below the median FC response after exposure to 300 cGy were classified as extremely radiation resistant. Twenty-one tumors were evaluated for synergistic response using the combination of chemo and RT with a median FC of 0.27 (+/-0.27) for 6.0 Gy of RT alone, 0.22 (+/-0.21) for CDDP alone, and 0.05 (+/-0.08) for the combination. A CI of 0.35 and an R value of 0.09 demonstrated synergy between chemo and RT without cross-resistance. Similar synergy without cross-resistance was found for RT in combination with BCNU, BSO, and TAX. CONCLUSIONS: Heterogeneous RT dose-response relationships in the in vitro assay were demonstrated. Explants were more sensitive to RT than cell lines. Unlike cell lines, fresh tumor cells consistently displayed synergy with RT and chemo. The synergy between RT and BSO suggests that glutathione depletion may enhance the effect of RT. The assay was feasible for examining fresh tumors and may be an important tool for studying RT or drug resistance. Clinical trials to evaluate this assay are indicated.