Jon Stobo

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.

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.

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.

Safety and efficacy of pulsed imatinib with or without G‐CSF versus continuous imatinib in chronic phase chronic myeloid leukaemia patients at 5 years follow‐up

Despite their efficacy in inducing deep and durable responses in chronic phase (CP) chronic myeloid leukaemia (CML) patients, BCR-ABL1 tyrosine kinase inhibitors (TKI) do not eradicate leukaemia stem cells (LSC), as proven by the persistence of BCR-ABL1+ CD34+, colony forming, longterm culture-initiating cells in the bone marrow of patients in sustained molecular response 4 5 (a 4 5-log reduction of BCR-ABL1 transcript levels, MR4 5) following TKI therapy (Chomel et al, 2011). CML LSC survival is independent of BCR-ABL1 kinase activity (Hamilton et al, 2012) and their quiescence is a putative TKI-resistance mechanism causing disease persistence. Moreover TKI exert anti-proliferative rather than pro-apoptotic effects against CML LSCs and might further contribute to disease persistence (Graham et al, 2002). Promoting LSC cellcycle entry using granulocyte-colony stimulating factor (G-CSF) has been shown in vitro to restore their sensitivity to TKI and enhance their eradication (Jorgensen et al, 2006). Based on this evidence, we performed a randomized phase II study (GIMI, EudraCT 2004-000179-33), which compared the safety and efficacy of continuous imatinib (cIM) versus pulsed imatinib (pIM) alone or with G-CSF (pIM+G) therapy administered in 4-week cycles for 48 weeks (12 cycles in total) in CP CML patients with at least a complete cytogenetic response (CCyR) on IM (Drummond et al, 2009) (see reference for study design, primary and secondary endpoints, patient demographics and disease characteristics). The experimental arms were expected to improve CML LSCs eradication by reducing TKI-induced quiescence (pIM) and/or by actively pushing CML LSCs into cell-cycle (pIM+G). At 2 years follow-up no statistically significant differences for the study endpoints were observed, possibly due to the limited numbers (15 patients per arm). However, 6/30 patients across the two experimental arms exhibited either loss of CCyR or major molecular response (MMR) as compared with only 1/15 in the cIM arm, with all but one patient in the experimental arms regaining MMR on restarting continuous IM or nilotinib therapy (Drummond et al, 2009). These results raised some concerns that the experimental schedules might have contributed to the loss of response. Subsequently, a mathematical model of the safety and efficacy of the IM and G-CSF combination suggested that this approach might be detrimental in the shortto mediumterm for patients with persistent disease treated with IM, by increasing the LSCs burden through enhanced proliferation, thus in turn increasing the risk of acquiring a resistance mutation and of disease progression. However, in the longterm (>2500 d, i.e. 6 8 years, from start of treatment), such an approach was predicted to prove beneficial as it would deplete the CML LSCs by increasing their susceptibility to TKI (Foo et al, 2009). Here we report the 5-year follow-up data for the GIMI study. 41/45 patients were available for analysis; four patients had died (one only as a result of CML progression). The median follow-up was 5 67 years. Using an intention to treat analysis, both CCyR and MMR rates were similar among treatment arms with no differences in progression rates. 5/15 patients in the cIM arm compared to 3/15 patients in each experimental arm changed treatment to second generation TKI (Table I).

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

Highlights • The manuscript details the rationale, design and protocol for PARADIGM-2.• PARADIGM-2 comprises two parallel phase I, dose escalation studies of the PARP inhibitor olaparib in combination with radiotherapy (for MGMT unmethylated patients) and radiotherapy-temozolomide (for MGMT methylated patients) in newly diagnosed glioblastoma.• This is a novel approach to phase I dose escalation trial design that maximises the potential for patients with glioblastoma to benefit from the addition of the radio- and chemosensitizing drug olaparib.

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

Highlights • A randomised phase II trial of radiotherapy dose escalation for pain control in MPM.• Comparison of 2 hypofractionated regimes (20 Gy/5# and 36 Gy/6#).• Highly conformal radiotherapy techniques used to aid safe dose escalation.• Primary outcome: pain control at week 5 at radiotherapy site.• Recruitment target: 112 patients from 10 to 15 UK centres.