Abstract IA-006: Enhancing the therapeutic ratio for glioblastoma by combining radiation therapy with PARP inhibitors

PARP inhibitors (PARPi) enhance radiation sensitivity in multiple cancer models, both in vitro and in vivo. Our observation that the radiosensitizing properties of PARPi are most pronounced in rapidly proliferating cells is reflected in early phase clinical trial data showing exacerbation of acute radiation toxicity in rapidly proliferating tissues such as oropharyngeal and esophageal mucosa. Lack of radiosensitization in late responding, slowly proliferating normal tissues indicates that PARPi may be more effectively combined with radiation therapy (RT) in patients with brain tumors. We are therefore evaluating the oral PARPi olaparib in combination with RT and/or temozolomide (TMZ) in the treatment of glioblastoma (GBM), the most prevalent and most aggressive primary brain tumor. Patients with GBM experience very poor outcomes in terms of median survival (c.1 year) and neurocognitive decline caused primarily by RT. Olaparib was initially evaluated in combination with daily low-dose TMZ in patients with recurrent GBM in the OPARATIC trial. Pharmacokinetic studies revealed that olaparib penetrates both core and margin regions of GBM, indicating that the BBB is significantly disrupted throughout these tumors. Olaparib could be safely combined with daily TMZ (75 mg/m2), but intermittent olaparib dosing (150 mg three days per week) was required to avoid dose-limiting hematological toxicity. Early phase testing of the olaparib-radiotherapy combination is now underway in three populations of patients with newly diagnosed GBM. Patients aged >65 with MGMT unmethylated GBM are being recruited to a randomized, placebo-controlled phase II study (PARADIGM) after a phase I dose escalation study showed that olaparib (200 mg twice daily) was extremely well tolerated when combined with brain irradiation (40 Gray in 15#). Good performance status patients aged <70 are being recruited to two parallel phase I dose escalation studies: patients with MGMT unmethylated tumors are receiving daily olaparib with RT (60 Gy in 30#) without TMZ, while patients with MGMT methylated tumors are receiving intermittent olaparib with standard chemoradiation (60 Gy). The impact of PARPi on RT induced neurotoxicity is being investigated in preclinical studies. In vitro data show that PARPi reduce proliferation of neural stem cells and protect them against RT induced apoptosis, while in vivo studies support the emerging concept that RT induced neuroinflammation is important in the pathogenesis of neurotoxicity. Importantly, preliminary PET and immunohistochemical studies have shown robust anti-neuroinflammatory effects of PARPi in this context. Ongoing experiments are defining the roles of microglia, astrocytes and neurogenesis in this phenomenon. These diverse data sets provide support for our hypothesis that combining PARPi with RT has potential to improve outcomes for GBM patients by enhancing tumor control while simultaneously suppressing neuroinflammation and alleviating RT related neurocognitive decline.

Citation Format: Anthony J. Chalmers, Rodrigo Gutierrez-Quintana, David J. Walker, Karin Williams, Duncan Forster, Mark R. Jackson, Sarah Derby, Jon Stobo, Lorna Sweeting, Caroline Kelly, Stephen Durant, Kaye J. Williams. Enhancing the therapeutic ratio for glioblastoma by combining radiation therapy with PARP inhibitors [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-006.

A randomised phase II trial of hydroxychloroquine and imatinib versus imatinib alone for patients with chronic myeloid leukaemia in major cytogenetic response with residual disease

In chronic-phase chronic myeloid leukaemia (CP-CML), residual BCR-ABL1+ leukaemia stem cells are responsible for disease persistence despite TKI. Based on in vitro data, CHOICES (CHlorOquine and Imatinib Combination to Eliminate Stem cells) was an international, randomised phase II trial designed to study the safety and efficacy of imatinib (IM) and hydroxychloroquine (HCQ) compared with IM alone in CP-CML patients in major cytogenetic remission with residual disease detectable by qPCR. Sixty-two patients were randomly assigned to either arm. Treatment 'successes' was the primary end point, defined as ≥0.5 log reduction in 12-month qPCR level from trial entry. Selected secondary study end points were 24-month treatment 'successes', molecular response and progression at 12 and 24 months, comparison of IM levels, and achievement of blood HCQ levels >2000 ng/ml. At 12 months, there was no difference in 'success' rate (p = 0.58); MMR was achieved in 80% (IM) vs 92% (IM/HCQ) (p = 0.21). At 24 months, the 'success' rate was 20.8% higher with IM/HCQ (p = 0.059). No patients progressed. Seventeen serious adverse events, including four serious adverse reactions, were reported; diarrhoea occurred more frequently with combination. IM/HCQ is tolerable in CP-CML, with modest improvement in qPCR levels at 12 and 24 months, suggesting autophagy inhibition maybe of clinical value in CP-CML.

PRIMUS-002: A multicentre, open-label, phase II study examining FOLFOX and nab-paclitaxel (FA) and nab-paclitaxel and gemcitabine (AG) as neoadjuvant therapy for (borderline) resectable pancreatic cancer (PC), focusing on biomarker and liquid biopsy development

TPS4166

Background: There is increasing evidence suggesting benefit from a neoadjuvant approach to PC. However, the optimal regimen is unclear and will likely require a precision medicine approach, where patient and tumor attributes define therapy. Platinum-containing regimens have shown survival benefit for PC, with occasional exceptional responders, but biomarkers (BM) of response are not well defined and treatment decisions are often based on patient performance status (PS) and co-morbidity. Tumors with defects in BRCA1/2and other Fanconi Anemia genes show defective DNA damage response (DDR), conferring potential selective sensitivity to DNA-damaging agents (e.g. platinum) and newer targeted agents. We have shown that DDR deficiency (DDRd) is present in up to 20% of PC. This study aims to exploit DDRd as a therapeutic vulnerability, with integrated analysis to define candidate BM for FA and AG response. Methods: PRIMUS-002 will enroll patients registered on the Precision-Panc Master Protocol who are molecularly profiled using the Precision-Panc Clinical Cancer Genome including a novel DDRd assay, and the transcriptome with longitudinal sampling (pre-, during, and post-treatment). Patients receive either FA ( nab-paclitaxel 150mg/m2IV,oxaliplatin 85mg/m2, folinic acid 350mg flat dose, fluorouracil infusion 2400mg/m2continuous IV infusion), orAG ( nab-paclitaxel 125mg/m2, gemcitabine 1000 mg/m2) for 3 months,based on patient age and PS.Following initial safety analysis, chemoradiation may be introduced. The primary endpoint is disease progression (DP) during neoadjuvant therapy. The study is designed to detect a 20% difference in DP between the BM+ve (10%) and BM –ve (30%) in patients treated with FA (90% power, 5% 1-sided level of statistical significance)., Exploratory translational endpoints include surrogate therapeutic response assessment using CA19.9, PET-CT SUV, DWI-MRI and ctDNA. Current Enrolment: 2 patients enrolled to date: 1 to receive FA and 1 to AG treatment. Clinical trial information: ISRCTN34129115.

The impact of heart radiation dose in lung SABR

e20054

Background: Lung cancer has poor outcomes, but those patients diagnosed with stage 1 NSCLC have 5-year survival of 60-70%. Stereotactic ablative body radiotherapy (SABR) is routinely considered for patients unfit for surgery. SABR is very well tolerated hence a treatment option for patients unfit for surgery, with > G2 lung toxicity of 1.8-9.1%, but propensity-matched analyses of stage 1 NSCLC treated with surgery or SABR have shown superiority of surgery in terms of overall survival, but not lung cancer-specific survival. Excess risk of CVD is a complication of breast cancer RT, but there is limited evidence in lung cancer. The aims of this study is to investigate the impact of radiation dose to the heart in lung SABR. Methods: In a single centre from November 2011-2012, patients who treated with lung SABR outwith the “no fly zone”, using ROSEL guidelines for OARS and with the lowest or highest heart maximum point dose were selected. 9 patients in each group were analysed for dose and clinical factors retrospectively from electronic patient notes. Results: The median (range) heart dose of the high dose (HD) group was 25.3Gy (17.6–34.1) and that of the low dose (LD) group was 0.88Gy (0.18–4.8). At the end of a median follow-up of 6.7 years, OS was poorer in the HD group at 11% than the LD group at 56% (p = 0.127). While 5-year cancer-specific mortality was similar in both groups at 22%, non-cancer-associated mortality was higher in HD (44% vs 11%, p = 0.127). In addition, HD were associated with a greater risk of CV hospital admission (56% vs 11%, p = 0.131) and new cardiac abnormalities (56% vs 0%, p = 0.029). Conclusions: In this group of medically unfit NSCLC patients treated with lung SABR, there were differences in outcome possibly associated with heart dose. The HD group showed higher mortality, specifically non-cancer-related mortality and cardiac events. Investigation of a larger cohort is warranted. [Table: see text]

Correction: Safety and utility of image-guided research biopsies in relapsed high-grade serous ovarian carcinoma-experience of the BriTROC consortium

This article was originally published under a CC BY NC SA License, but has now been made available under a CC BY 4.0 License.

SYSTEMS-2: A randomised phase II study of radiotherapy dose escalation for pain control in malignant pleural mesothelioma

SYSTEMS-2 is a randomised study of radiotherapy dose escalation for pain control in 112 patients with malignant pleural mesothelioma (MPM). Standard palliative (20 Gy/5#) or dose escalated treatment (36 Gy/6#) will be delivered using advanced radiotherapy techniques and pain responses will be compared at week 5. Data will guide optimal palliative radiotherapy in MPM.

PARADIGM-2: Two parallel phase I studies of olaparib and radiotherapy or olaparib and radiotherapy plus temozolomide in patients with newly diagnosed glioblastoma, with treatment stratified by MGMT status

Glioblastoma has a dismal prognosis and molecular targeted agents have failed to improve outcomes to date. PARADIGM-2 is a phase I dose escalation study evaluating olaparib plus radiotherapy ± temozolomide in newly diagnosed glioblastoma, using MGMT methylation status to stratify patients and inform treatment schedules.

Randomized Phase II Study Investigating Pazopanib Versus Weekly Paclitaxel in Relapsed or Progressive Urothelial Cancer

Purpose Two previous single-arm trials have drawn conflicting conclusions regarding the activity of pazopanib in urothelial cancers after failure of platinum-based chemotherapy. Patients and Methods This randomized (1:1) open-label phase II trial compared the efficacy of pazopanib 800 mg orally with paclitaxel (80 mg/m2 days 1, 8, and 15 every 28 days) in the second-line setting. The primary end point was overall survival (OS). Results Between August 2012 and October 2014, 131 patients, out of 140 planned, were randomly assigned. The study was terminated early on the recommendation of the independent data monitoring committee because of futility. Final analysis after the preplanned number of deaths (n = 110) occurred after a median follow-up of 18 months. One hundred fifteen deaths had occurred at the final data extract presented here. Median OS was 8.0 months for paclitaxel (80% CI, 6.9 to 9.7 months) and 4.7 months for pazopanib (80% CI, 4.2 to 6.4 months). The hazard ratio (HR) adjusted for baseline stratification factors was 1.28 (80% CI, 0.99 to 1.67; one-sided P = .89). Median progression-free survival was 4.1 months for paclitaxel (80% CI, 3.0 to 5.6 months) and 3.1 months for pazopanib (80% CI, 2.7 to 4.6 months; HR, 1.09; 80% CI, 0.85 to 1.40; one-sided P = .67). Discontinuations for toxicity occurred in 7.8% and 23.1% for paclitaxel and pazopanib, respectively. Conclusion Pazopanib did not have greater efficacy than paclitaxel in the second-line treatment of urothelial cancers. There was a trend toward superior OS for paclitaxel.

Safety and utility of image-guided research biopsies in relapsed high-grade serous ovarian carcinoma-experience of the BriTROC consortium

BACKGROUND

Investigating tumour evolution and acquired chemotherapy resistance requires analysis of sequential tumour material. We describe the feasibility of obtaining research biopsies in women with relapsed ovarian high-grade serous carcinoma (HGSC).

METHODS

Women with relapsed ovarian HGSC underwent either image-guided biopsy or intra-operative biopsy during secondary debulking, and samples were fixed in methanol-based fixative. Tagged-amplicon sequencing was performed on biopsy DNA.

RESULTS

We screened 519 patients in order to enrol 220. Two hundred and two patients underwent successful biopsy, 118 of which were image-guided. There were 22 study-related adverse events (AE) in the image-guided biopsies, all grades 1 and 2; pain was the commonest AE. There were pre-specified significant AE in 3/118 biopsies (2.5%). 87% biopsies were fit-for-purpose for genomic analyses. Median DNA yield was 2.87 μg, and was higher in biopsies utilising 14 G or 16 G needles compared to 18 G. TP53 mutations were identified in 94.4% patients.

CONCLUSIONS

Obtaining tumour biopsies for research in relapsed HGSC is safe and feasible. Adverse events are rare. The large majority of biopsies yield sufficient DNA for genomic analyses-we recommend use of larger gauge needles and methanol fixation for such biopsies, as DNA yields are higher but with no increase in AEs.

Pain in Malignant Pleural Mesothelioma: A Prospective Characterization Study

INTRODUCTION

Malignant pleural mesothelioma (MPM) is associated with severe pain. The underlying neurobiology of this is complex. The primary aim of this study was to characterize pain in MPM.

METHODS

This study was undertaken as part of a trial examining radiotherapy for the treatment of pain in MPM (ISRCTN 10644347). Patients had MPM with associated pain for which radiotherapy was planned and a worst pain score ≥ 4/10. The following assessments were undertaken: clinical neuropathic pain assessment, Brief Pain Inventory (BPI), Leeds Assessment of Neuropathic Symptoms and Signs (LANSS), Short form of the McGill Pain Questionnaire (SF-MPQ), and Quantitative Sensory Testing (QST). The relationship of these characteristics and response to radiotherapy was assessed. Unless stated, medians and interquartile range (IQR) are used.

RESULTS

Thirty-seven patients were recruited. Average pain and worst pain was 4 (4-6) and 8 (6-8), respectively. Higher average pain and higher worst pain scores were associated with higher interference scores on the BPI, P < 0.001 and P < 0.0005. Twenty patients (54%) had a clinical diagnosis of neuropathic pain, and of these, only six patients (40%) screened positively for neuropathic pain using the LANSS. Patients with a high LANSS also had higher BPI and SF-MPQs. The presence of neuropathic pain (clinically or by LANSS) did not predict response to radiotherapy, P < 0.05. The SF-MPQ scores were higher in those with abnormal cool sensation on QST (P = 0.016).

CONCLUSION

Pain in mesothelioma varies among patients and may have neuropathic components. An adequate pain assessment is necessary to guide the clinician in the appropriate choice of analgesics.

Is Radiotherapy Useful for Treating Pain in Mesothelioma?: A Phase II Trial

INTRODUCTION

Radiotherapy is often used to treat pain in malignant pleural mesothelioma (MPM), although there is limited evidence to support this. The aim of this trial was to assess the role of radiotherapy for the treatment of pain in MPM.

METHODS

A multicentre, single arm phase II trial was conducted. Eligible patients fulfilled the following criteria: pathological or radiological diagnosis of MPM; pain secondary to MPM; radiotherapy indicated for pain control; and more than 18 years of age. Patients had assessments of pain and other symptoms at baseline and then received 20 Gy in five daily fractions. Key follow-up points were 5 and 12 weeks posttreatment. The primary end point measure was assessment of pain at the site of radiotherapy at 5 weeks. Secondary end points included effects on quality of life, breathlessness, fatigue, mood, toxicity, and the radiological response.

RESULTS

Forty patients were recruited from three UK oncology centers. Fourteen patients had a clinically meaningful improvement in their pain 5 weeks post radiotherapy (intention to treat), with five patients having a complete improvement. On the basis of a complete case analysis of the 30 patients assessable at week 5, 47% (confidence intervals, 28.3-65.7) of patients alive at week 5 had an improvement in their pain. There was no improvement in other key symptoms or quality of life.

CONCLUSIONS

Radiotherapy for pain control in MPM is an effective treatment in a proportion of patients. Future studies examining differing radiotherapy regimens with a view to improving response rates are warranted.

Targeting primitive chronic myeloid leukemia cells by effective inhibition of a new AHI-1-BCR-ABL-JAK2 complex

Background

Imatinib mesylate (IM) induces clinical remission of chronic myeloid leukemia (CML). The Abelson helper integration site 1 (AHI-1) oncoprotein interacts with BCR-ABL and Janus kinase 2 (JAK2) to mediate IM response of primitive CML cells, but the effect of the interaction complex on the response to ABL and JAK2 inhibitors is unknown.

Methods

The AHI-1–BCR-ABL–JAK2 interaction complex was analyzed by mutational analysis and coimmunoprecipitation. Roles of the complex in regulation of response or resistance to ABL and JAK2 inhibitors were investigated in BCR-ABL⁺ cells and primary CML stem/progenitor cells and in immunodeficient NSG mice. All statistical tests were two-sided.

Results

The WD40-repeat domain of AHI-1 interacts with BCR-ABL, whereas the N-terminal region interacts with JAK2; loss of these interactions statistically significantly increased the IM sensitivity of CML cells. Disrupting this complex with a combination of IM and an orally bioavailable selective JAK2 inhibitor (TG101209 [TG]) statistically significantly induced death of AHI-1–overexpressing and IM-resistant cells in vitro and enhanced survival of leukemic mice, compared with single agents (combination vs TG alone: 63 vs 53 days, ratio = 0.84, 95% confidence interval [CI] = 0.6 to 1.1, P = .004; vs IM: 57 days, ratio = 0.9, 95% CI = 0.61 to 1.2, P = .003). Combination treatment also statistically significantly enhanced apoptosis of CD34⁺ leukemic stem/progenitor cells and eliminated their long-term leukemia-initiating activity in NSG mice. Importantly, this approach was effective against treatment-naive CML stem cells from patients who subsequently proved to be resistant to IM therapy.

Conclusions

Simultaneously targeting BCR-ABL and JAK2 activities in CML stem/progenitor cells may improve outcomes in patients destined to develop IM resistance.

The role of the T3/antigen receptor complex in T-cell activation

The role of the T3/antigen receptor complex is summarized by the diagram presented in Figure 4. Signals transmitted through T3/Ti activate a phosphodiesterase. This enzyme acts on its substrate PIP2 to generate two important mediators, IP3 and diacylglycerol. IP3 mobilizes calcium from bound intracellular stones. This increase in [Ca2+]i is one intracellular signal which, in conjunction with others, induces expression of lymphokine genes by influencing pretranslational, presumably transcriptional, events. Several problems remain. Which of the five molecules in the T3/Ti complex serves as the effector molecule in the transmembrane signaling process is not known. Which molecules serve to link T3/Ti to the phosphodiesterase enzyme is under investigation. The role diacylglycerol protein kinase C and other mediators play in signalling activation is not established. Finally, for those events occurring after the early events pictured in Figure 4 that result in gene activation, the sequence is a black box. Approaches to address each of these questions are available, and answers should be forthcoming.

Activation of a human T cell line: a two-stimulus requirement in the pretranslational events involved in the coordinate expression of interleukin 2 and gamma-interferon genes

In the resting state, the T3-positive, human T cell line Jurkat does not synthesize detectable amounts of either interleukin 2 (IL 2) or gamma-interferon (IFN-gamma). Activation of Jurkat as measured by the secretion of substantial amounts of both lymphokines requires two distinct signals. One signal is produced by the phorbol ester, phorbol myristate acetate, and the other by either phytohemagglutinin or antibodies to T3. To elucidate the molecular events by which these activation signals lead to the synthesis of IL 2 and IFN-gamma activity we used cDNA probes to follow the appearance of IL 2 and IFN-gamma-specific transcripts after activation of Jurkat. These studies demonstrate that both signals are required for the appearance of IL 2 or IFN-gamma-specific transcripts and that the appearance of IL 2 and IFN-gamma RNA is coordinate with regard to a) the signals required for their production, b) the kinetics of their appearance, and c) the inhibition of their appearance by cyclosporin A. These studies suggest that distinct T cell-activation signals may operate through a common regulatory pathway involved in the expression of both IL 2 and IFN-gamma genes.

Activation of a human T cell line: a two-stimulus requirement in the pretranslational events involved in the coordinate expression of interleukin 2 and gamma-interferon genes

In the resting state, the T3-positive, human T cell line Jurkat does not synthesize detectable amounts of either interleukin 2 (IL 2) or gamma-interferon (IFN-gamma). Activation of Jurkat as measured by the secretion of substantial amounts of both lymphokines requires two distinct signals. One signal is produced by the phorbol ester, phorbol myristate acetate, and the other by either phytohemagglutinin or antibodies to T3. To elucidate the molecular events by which these activation signals lead to the synthesis of IL 2 and IFN-gamma activity we used cDNA probes to follow the appearance of IL 2 and IFN-gamma-specific transcripts after activation of Jurkat. These studies demonstrate that both signals are required for the appearance of IL 2 or IFN-gamma-specific transcripts and that the appearance of IL 2 and IFN-gamma RNA is coordinate with regard to a) the signals required for their production, b) the kinetics of their appearance, and c) the inhibition of their appearance by cyclosporin A. These studies suggest that distinct T cell-activation signals may operate through a common regulatory pathway involved in the expression of both IL 2 and IFN-gamma genes.

Acquired immunodeficiency syndrome: epidemiology, virology, and immunology

Acquired immunodeficiency syndrome indicates opportunistic infection or unusual malignancy associated with a marked deficiency of cell mediated immunity in the absence of any other cause of the immune defect. This review examines epidemiology, virology, and immunology associated with this disorder. The syndrome appears to be caused by infection of at-risk individuals by a retrovirus that has tropism for a specific population of T lymphocytes.

Role of T3 surface molecules in human T-cell activation: T3-dependent activation results in an increase in cytoplasmic free calcium

The human T-cell leukemia, Jurkat, and a T3-negative mutant of Jurkat (S.5) were used to study the role of T3 in human T-cell activation. Incubation of Jurkat with phytohemagglutinin (PHA) resulted in the production of interleukin 2, which was markedly increased by the addition of phorbol 12-myristate 13-acetate (PMA). Antibodies reactive with T3 could activate Jurkat only if added together with PMA. However, S.5 cells failed to produce interleukin 2 in response to PHA and produced 1/16th the interleukin 2 activity that Jurkat produced in response to PHA and PMA. Incubation of S.5 cells with the calcium ionophore A23187 and PMA resulted in the production of interleukin 2 activity comparable to that produced by Jurkat. Like antibodies reactive with T3, A23187 demonstrated an obligate requirement for PMA in order to activate Jurkat or S.5. These observations suggested that T3 might participate in T-cell activation through mechanisms that increase intracellular Ca2+. This was examined by using the Ca2+ sensitive fluor, quin-2, to measure levels of cytoplasmic free Ca2+ [( Ca2+]i). Addition of PHA, A23187, or monoclonal antibodies reactive with T3 to Jurkat cells resulted in substantial increases of [Ca2+]i. In contrast, only A23187 could induce an increase in [Ca2+]i in S.5 cells. Three other monoclonal antibodies reactive with other membrane antigens expressed on Jurkat or S.5 did not increase [Ca2+]i. These results suggest that T3 and/or associated molecules participate in T-cell activation through mechanisms that lead to increases in [Ca2+]i and that their expression is a relative requirement for T-cell activation by PHA.

T-cell macrophage subset interactions and decreased autologous mixed lymphocyte reaction in Sjögren's syndrome

T-cell macrophage subset interactions were studied in relation to the decreased autologous mixed lymphocyte reaction (AMLR) in 15 patients with Sjögren's syndrome (SS). Monoclonal antibodies against a macrophage (M theta) subset (Mac-120) stimulatory in the AMLR and against nonpolymorphic determinants of Ia antigen were used to identify adherent M theta. Four patients with decreased AMLR had a reduced percentage of Mac-120+ cells, suggesting that a defect in stimulatory M theta may account for their decreased AMLR. No correlation was found between the magnitude of the AMLR and the percentage of Ia+ M theta. Another six patients with diminished AMLR had a normal to high percentage of Mac-120+ M theta. However, this group of SS patients showed a decreased response to Concanavalin A, suggesting that they may have a defect in the responding T cells. Patients with normal AMLR had normal percentages of Mac-120+ M theta and showed normal responses to T-cell mitogens and alloantigens. These results suggest that a defective AMLR may have multiple causes. SS patients are heterogeneous in this regard and can be sorted into three groups using the AMLR and monoclonal antibodies.