Over the last decade, next generation sequencing has enabled classification of multiple new recurrent genomic drivers of acute lymphoblastic leukemia (ALL). The aim of this study was to describe the genomic drivers of ALL in an adolescent and young adult (AYA) cohort (ALL06 target age 15-39 years, recruited age 16.6-39 years), treated uniformly on a pediatric inspired protocol (the Australasian Leukaemia and Lymphoma Group (ALLG) ALL06 study). ALL06 assessed the safety and efficacy of adapting a pediatric chemotherapy protocol in older patients. Genomic risk classification of B- and T-ALL patients enrolled to the study was based on the use of multiple assays: mRNA-Sequencing, Multiplex Ligation-dependent Probe Amplification (MLPA), immunophenotyping and cytogenetics. Using this approach, 36/40 (90%) B- and 13/17 (76.5%) T-ALL patients were classified according to genomic risk. A strong correlation existed between adverse genomic risk and minimal residual disease (MRD) at the end of consolidation, translating to inferior overall and relapse free survival. Patients with adverse risk genomics who achieved negative MRD status had improved responses compared to those with persistent MRD. Patients with standard risk genomics had excellent responses regardless of MRD status. This is the first report of the impact of genomics in an individual cohort of AYA patients treated on a single protocol. These data argue strongly for incorporation of a genomic risk classification into future ALL treatment paradigms at the time of diagnosis, and also for the rigorous assessment of risk assignments in a group of patients who are not children and not older adults. ACTRN12611000814976 https://anzctr.org.au/

Resistance, to therapeutic antibodies used to treat chronic lymphocytic leukemia (CLL) patients is common. Monocyte-derived macrophages (MDMs) are a major effector of antitumour responses to therapeutic antibodies and we have previously reported that resistance to therapeutic antibodies, by MDMs, increases as CLL disease progresses. In this study, we examine the effect of a Class IIa-selective HDAC inhibitor (TMP195) on the phagocytic response to opsonised tumor cells or non-opsonised targets by MDMs derived from CLL patients. We report that TMP195 enhances phagocytic responses to antibody-opsonised CLL cells and E. coli within 30 min of treatment. The enhanced response is phenocopied by knockdown of the Class IIa HDAC, HDAC7, or by low concentrations of the pan-HDAC inhibitor, vorinostat. HDAC7 knockdown and inhibition induces hyperacetylation and hyperphosphorylation of Bruton’s tyrosine kinase (BTK). Moreover, BTK inhibitors abrogated the enhanced response to HDAC7 inhibition. Our data show that HDAC7 is an actionable driver of resistance to therapeutic antibodies by MDMs derived from CLL patients.

Background:Paediatric inspired regimens have improved survival in AYA ALL. However, results remain inferior when compared to children likely associated with the poorer tolerability of paediatric regimens and unique biology of ALL in the AYA population.Aims:The objective of ALL06 was to assess whether a BFM based protocol could be administered to patients (pts) aged 15–40 years (yrs) in a comparable time frame to paediatric pts (aged <15 yrs) treated using the same induction therapy as part of the ANZCHOG Study 8 protocol. The primary outcome was the proportion of pts commencing protocol M or High Risk (HR) Block 1 by day 94. The study design permitted direct comparison of dose delivery during induction between the ALL06 and Study 8 cohorts.Methods:Previously untreated pts with Ph‐negative ALL were eligible for enrolment. Treatment consisted of 2 years of therapy including induction phase I and II, protocol M, reinduction phase I and II and maintenance therapy. Minimal Residual Disease (MRD) was assessed centrally using RQ‐PCR assays with a sensitivity of 10–4 or greater at day 33 and day 79 of induction and reported according to EuroMRD criteria. Stratification to HR therapy was based on diagnostic and treatment response criteria with the aim of eliminating MRD prior to allogeneic transplantation if a suitable donor was available or further intensive chemotherapy.Results:86 pts were enrolled on ALL06 from 07/12 to 06/18. 3 were considered ineligible. Median age was 24 (16 – 38) yrs. Most had B‐cell ALL (72.3%) and were male (72.0%). Considering the primary objective, 41.0% (95%CI 30.3 – 52.3%) of the ALL06 cohort commenced protocol M or HR1 by day 94 vs 39.3% in Study 8 (p = 0.77). For ALL06, median time to protocol M/HR1 was 97 (78 – 139) days vs 98 days in Study 8 (p = 0.85). CR rates at day 33 and day 79 were 90.4% and 97.6%. To date there have been 19 deaths (n = 9 due to relapse) and 19 relapses. Of 10 treatment related deaths, 4 (4.8%) occurred during induction (1 = pancreatitis, 1 = cerebral venous thrombosis, 2 = sepsis). 13 pts remain on therapy. With median follow up of 27.4 months, 2 yr DFS and OS was 75.6% (95%CI 65.6 – 85.5%) and 78.4% (95% CI 68.9 – 87.9%). 2 yr DFS and OS for the standard/medium risk group was 89.6% (95%CI 78.4–100%) and 97.1% (95%CI 91.4–100%) vs 66.3% (95%CI 49.1–83.5%) and 67.3% (95%CI 49.5–85%) for higher risk groups (p = 0.012 and 0.002 respectively). MRD results were available in 66 pts at day 33 and 70 pts at day 79. Day 33 and day 79 MRD results were as follows: MRDneg 18.2% and 58.6%, MRDlow pos (<5 x 10–4) 33.3% and 18.6% and MRDhigh pos (≥5 x 10–4) 48.5% and 22.9%. 2 yr DFS and OS for the day 79 MRDneg cohort was 91.4% (95%CI 82.1–100%) and 97.5% (95%CI 92.7–100%) vs 57.7% (95%CI 37.3–78%) and 57.8% (95%CI 36.3–79.2%) for the combined MRDlow pos/MRDhigh pos group (p = 0.003 and <0.001 respectively). T vs B phenotype was associated with improved 2yr DFS 94.7% (95%CI 84.7–100%) vs 66.2% (95%CI 52.3–80%, p = 0.036) but not 2 yr OS (90.5% vs 72.0%, p = 0.117).Summary/Conclusion:BFM style induction is equally as deliverable in an AYA population as in children with ALL. 2 yr DFS and OS compares favourably with other study group outcomes in this population. Risk stratification incorporating centralised MRD testing was feasible in the context of a national multicentre trial. Our findings suggest that intolerance to induction therapy is not a major contributor to inferior outcomes in the AYA cohort. This first ALLG study using a BFM regimen will be used to incorporate novel therapies targeting the unique biology of AYA ALL.

Chronic lymphocytic leukaemia (CLL) is the most common adult leukaemia and, in some patients, is accompanied by resistance to both chemotherapeutics and immunotherapeutics. In this review we will discuss the role of tumour associated macrophages (TAMs) in promoting CLL cell survival and resistance to immunotherapeutics. In addition, we will discuss mechanisms by which TAMs suppress T-cell mediated antitumour responses. Thus, targeting macrophages could be used to i) reduce the leukaemic burden via the induction of T-cell-mediated antitumour responses, ii) to reduce pro-survival signalling and enhance response to conventional chemotherapeutics or iii) enhance the response to therapeutic antibodies in current clinical use.

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia. While therapeutic antibodies show clinical activity in CLL patients, resistance inevitably develops resulting in treatment failure. Identifying mechanisms of antibody resistance and methods to reduce resistance would be valuable in managing CLL. Monocyte derived cells (MDCs), also known as nurse like cells (NLCs) in CLL [1], [2], are known to be crucial components of the CLL microenvironment network and following "maturation" in in vitro culture systems are able to provide support for the survival of the malignant B cells from CLL patients. In addition to their protective role, MDCs are key effector cells in mediating responses to therapeutic antibody therapies [3]. We have determined that macrophages from patients with early stable CLL are able to elicit superior cytotoxic response to therapeutic antibodies than macrophages derived from patients with progressive CLL. We have exploited this unique finding to gain insight into antibody resistance. Thus, we have profiled monocytes on day 0 and MDCs on day 7 from antibody sensitive and antibody resistant CLL patients (GEO accession number GEO: GSE71409). We show that there are no significant differences in transcriptomes from the monocytes or MDCs derived from sensitive or resistant patient samples. However, we show that MDCs acquire an M2-like macrophage transcriptomic signature following 7 days culture regardless of whether they were derived from sensitive or resistant patient samples.

Resistance to therapeutic antibodies in chronic lymphocytic leukaemia (CLL) is common. In this study, we show that therapeutic antibodies against CD62L (CD62L-Ab) or CD20 (obinutuzumab) were able to induce antibody-dependent cell-mediated cytotoxicity (ADCC) and phagocytosis (ADP) in primary cultures of CLL cells. CLL cells derived from patients with active disease requiring treatment displayed resistance to these antibodies, whereas patients with stable disease were sensitive. Using enrichment strategies and transcriptomic analyses, we show that antibody-dependent tumour cell killing was FcγR-dependent and mediated by macrophages. Moreover, we show that resistance cannot be attributed to total numbers or established subtypes of monocytes/macrophages, or the efficiency with which they bind an immune complex. Rather, ADCC/ADP resistance was due to reduced signalling activity through the activating FcγRs resulting in the transfer of dominance to the inhibitory FcγRIIb within macrophages. Most significantly, we show that resistance is an actionable event that could be reversed using inhibitors of FcγRIIb signalling in primary cultures of CLL cells that were previously insensitive to obinutuzumab or CD62L-Ab.

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