Paediatric Strategy Forum for medicinal product development of chimeric antigen receptor T-cells in children and adolescents with cancer: ACCELERATE in collaboration with the European Medicines Agency with participation of the Food and Drug Administration

The seventh multi-stakeholder Paediatric Strategy Forum focused on chimeric antigen receptor (CAR) T-cells for children and adolescents with cancer. The development of CAR T-cells for patients with haematological malignancies, especially B-cell precursor acute lymphoblastic leukaemia (BCP-ALL), has been spectacular. However, currently, there are scientific, clinical and logistical challenges for use of CAR T-cells in BCP-ALL and other paediatric malignancies, particularly in acute myeloid leukaemia (AML), lymphomas and solid tumours. The aims of the Forum were to summarise the current landscape of CAR T-cell therapy development in paediatrics, too identify current challenges and future directions, with consideration of other immune effector modalities and ascertain the best strategies to accelerate their development and availability to children. Although the effect is of limited duration in about half of the patients, anti-CD19 CAR T-cells produce high response rates in relapsed/refractory BCP-ALL and this has highlighted previously unknown mechanisms of relapse. CAR T-cell treatment as first- or second-line therapy could also potentially benefit patients whose disease has high-risk features associated with relapse and failure of conventional therapies. Identifying patients with very early and early relapse in whom CAR T-cell therapy may replace haematopoietic stem cell transplantation and be definitive therapy versus those in whom it provides a more effective bridge to haematopoietic stem cell transplantation is a very high priority. Development of approaches to improve persistence, either by improving T cell fitness or using more humanised/fully humanised products and co-targeting of multiple antigens to prevent antigen escape, could potentially further optimise therapy. Many differences exist between paediatric B-cell non-Hodgkin lymphomas (B-NHL) and BCP-ALL. In view of the very small patient numbers with relapsed lymphoma, careful prioritisation is needed to evaluate CAR T-cells in children with Burkitt lymphoma, primary mediastinal B cell lymphoma and other NHL subtypes. Combination trials of alternative targets to CD19 (CD20 or CD22) should also be explored as a priority to improve efficacy in this population. Development of CD30 CAR T-cell immunotherapy strategies in patients with relapsed/refractory Hodgkin lymphoma will likely be most efficiently accomplished by joint paediatric and adult trials. CAR T-cell approaches are early in development for AML and T-ALL, given the unique challenges of successful immunotherapy actualisation in these diseases. At this time, CD33 and CD123 appear to be the most universal targets in AML and CD7 in T-ALL. The results of ongoing or planned first-in-human studies are required to facilitate further understanding. There are promising early results in solid tumours, particularly with GD2 targeting cell therapies in neuroblastoma and central nervous system gliomas that represent significant unmet clinical needs. Further understanding of biology is critical to success. The comparative benefits of autologous versus allogeneic CAR T-cells, T-cells engineered with T cell receptors T-cells engineered with T cell receptor fusion constructs, CAR Natural Killer (NK)-cell products, bispecific T-cell engager antibodies and antibody-drug conjugates require evaluation in paediatric malignancies. Early and proactive academia and multi-company engagement are mandatory to advance cellular immunotherapies in paediatric oncology. Regulatory advice should be sought very early in the design and preparation of clinical trials of innovative medicines, for which regulatory approval may ultimately be sought. Aligning strategic, scientific, regulatory, health technology and funding requirements from the inception of a clinical trial is especially important as these are very expensive therapies. The model for drug development for cell therapy in paediatric oncology could also involve a 'later stage handoff' to industry after early development in academic hands. Finally, and very importantly, strategies must evolve to ensure appropriate ease of access for children who need and could potentially benefit from these therapies.

The 2020 BMT CTN Myeloma Intergroup Workshop on Immune Profiling and Minimal Residual Disease Testing in Multiple Myeloma

The fifth annual Blood and Marrow Transplant Clinical Trials Network Myeloma Intergroup Workshop on Immune Profiling and Minimal Residual Disease Testing in Multiple Myeloma was conducted as one of the American Society of Hematology Annual Meeting Scientific Workshops on Thursday December 3, 2020. This workshop focused on four main topics: (1) integrating minimal residual disease into clinical trial design and practice; (2) the molecular and immunobiology of disease evolution and progression in myeloma; (3) adaptation of next-generation sequencing, next-generation flow cytometry, and cytometry by time of flight techniques; and (4) chimeric antigen receptor T-cell and other cellular therapies for myeloma. In this report, we provide a summary of the workshop presentations and discuss future directions in the field.

Fedratinib in patients with myelofibrosis previously treated with ruxolitinib: An updated analysis of the JAKARTA2 study using stringent criteria for ruxolitinib failure

Fedratinib is an oral, selective Janus kinase 2 (JAK2) inhibitor. The phase II JAKARTA2 study assessed fedratinib in patients with intermediate‐ or high‐risk myelofibrosis (MF) who were resistant or intolerant to prior ruxolitinib per investigator assessment. Patients received fedratinib 400 mg/day in 28‐day cycles. The JAKARTA2 outcomes were initially reported using a last‐observation‐carried forward (LOCF) analysis in a “Per Protocol” population. This updated analysis of JAKARTA2 employs intention‐to‐treat analysis principles without LOCF for all treated patients (ITT Population; N = 97), and for a patient subgroup who met more stringent definitions of prior ruxolitinib failure (Stringent Criteria Cohort; n = 79). Median duration of prior ruxolitinib exposure was 10.7 months. The primary endpoint was spleen volume response rate (SVRR; ≥35% spleen volume decrease from baseline to end of cycle 6 [EOC6]). The SVRR was 31% in the ITT Population and 30% in the Stringent Criteria Cohort. Median duration of spleen volume response was not reached. Symptom response rate (≥50% reduction from baseline to EOC6 in total symptom score [TSS] on the modified Myelofibrosis Symptom Assessment Form [MFSAF]) was 27%. Grade 3‐4 anemia and thrombocytopenia rates were 38% and 22%, respectively. Patients with advanced MF substantially pretreated with ruxolitinib attained robust spleen responses and reduced symptom burden with fedratinib.

Fedratinib (FEDR) in myelofibrosis (MF) patients previously treated with ruxolitinib (RUX): A reanalysis of the JAKARTA-2 study

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Background: MF is a life-threatening MPN for which RUX is the only approved treatment (Tx) option. Patients (pts) who are relapsed/refractory (R/R) or intolerant to RUX have a particularly high unmet medical need. FEDR is an oral selective JAK2 inhibitor active against wt and mut JAK2. The JAKARTA-2 study demonstrated ≥35% spleen volume responses (SVR) in pts resistant or intolerant to RUX per investigator assessment. This JAKARTA-2 reanalysis employs a more stringent definition of RUX failure than used in the previous analysis. Methods: Adult pts previously treated with RUX with intermediate or high-risk primary, post-PV, or post-ET MF, palpable splenomegaly, ECOG PS ≤2, and platelet counts ≥50 × 109/L received FEDR 400 mg QD in continuous 28-day cycles. The primary endpoint was spleen volume response rate (SVRR): ≥35% SVR from baseline (BL) at cycle 6 end per blinded central review of MRI/CT scans. A key secondary endpoint was symptom RR (≥50% decrease in total symptom score from BL). Results: 79/97 enrolled pts (81%) met the more stringent criteria for RUX R/R (n=65, 82%) or intolerance (n=14, 18%). Median BL spleen volume was 2946 mL (~14× normal). Median prior RUX Tx duration was 11.5 mo (range 1.0–62.4). Median number of FEDR Tx cycles was 7 (1–20). SVRR with FEDR was 30% (95% CI 21, 42). KM estimated median spleen response duration was not estimable (95% CI 7.2 mo, NE). Symptom RR was 27%. Safety was consistent with prior reports. Conclusions: FEDR provided clinically meaningful reductions in splenomegaly and symptom burden in pts with MF who met more stringent criteria for R/R or intolerance to RUX. Clinical trial information: NCT01523171. [Table: see text]

Patients with Slowly Proliferative Early Breast Cancer Have Low Five-Year Recurrence Rates in a Phase III Adjuvant Trial of Capecitabine

PURPOSE

We conducted a randomized phase III study to determine whether patients with early breast cancer would benefit from the addition of capecitabine (X) to a standard regimen of doxorubicin (A) plus cyclophosphamide (C) followed by docetaxel (T).

EXPERIMENTAL DESIGN

Treatment comprised eight cycles of AC→T (T dose: 100 mg/m(2) on day 1) or AC→XT (X dose: 825 mg/m(2) twice daily, days 1-14; T dose: 75 mg/m(2) on day 1). The primary endpoint was 5-year disease-free survival (DFS).

RESULTS

Of 2,611 women, 1,304 were randomly assigned to receive AC→T and 1,307 to receive AC→XT. After a median follow-up of 5 years, the study failed to meet its primary endpoint [HR, 0.84; 95% confidence interval (CI), 0.67-1.05; P = 0.125]. A significant improvement in overall survival, a secondary endpoint, was seen with AC→XT versus AC→T (HR, 0.68; 95% CI, 0.51-0.92; P = 0.011). There were no unexpected adverse events. Of patients with estrogen receptor (ER)-positive/HER2-negative disease, 70% of whom were node-positive, 26% and 59% had tumors with a centrally assessed Ki-67 score of <10% or <20%, respectively, and only 17 (2%) and 53 (6%) DFS events, respectively, occurred in these groups at 7 years.

CONCLUSIONS

The very low event rate in patients with ER-positive, low Ki-67 cancers, regardless of nodal status, strongly suggests that these patients should not be enrolled in adjuvant trials that assess 5-year DFS rates and that central Ki-67 analyses can identify these patients.

Phase I trial of capecitabine rapidly disintegrating tablets and concomitant radiation therapy in children with newly diagnosed brainstem gliomas and high-grade gliomas

BACKGROUND

We conducted a phase I study to estimate the maximum tolerated dose and describe the dose-limiting toxicities and pharmacokinetics of oral capecitabine rapidly disintegrating tablets given concurrently with radiation therapy to children with newly diagnosed brainstem or high-grade gliomas.

METHODS

Children 3-21 y with newly diagnosed intrinsic brainstem or high-grade gliomas were eligible for enrollment. The starting dose was 500 mg/m(2), given twice daily, with subsequent cohorts enrolled at 650 mg/m(2) and 850 mg/m(2) using a 3 + 3 phase I design. Children received capecitabine at the assigned dose daily for 9 wks starting from the first day of radiation therapy (RT). Following a 2-wk break, patients received 3 courses of capecitabine 1250 mg/m(2) twice daily for 14 days followed by a 7-day rest. Pharmacokinetic sampling was performed in consenting patients. Six additional patients with intrinsic brainstem gliomas were enrolled at the maximum tolerated dose to further characterize the pharmacokinetic and toxicity profiles.

RESULTS

Twenty-four patients were enrolled. Twenty were fully assessable for toxicity. Dose-limiting toxicities were palmar plantar erythroderma (grades 2 and 3) and elevation of alanine aminotransferase (grades 2 and 3). Systemic exposure to capecitabine and metabolites was similar to or slightly lower than predicted based on adult data.

CONCLUSIONS

Capecitabine with concurrent RT was generally well tolerated. The recommended phase II capecitabine dose when given with concurrent RT is 650 mg/m(2), administered twice daily. A phase II study to evaluate the efficacy of this regimen in children with intrinsic brainstem gliomas is in progress (PBTC-030).

Diverse pathways mediate chemotherapy-induced cell death in acute lymphoblastic leukemia cell lines

Cancer cell resistance to chemotherapy may be mediated by defects in apoptotic pathways. A prior study showed that in vivo apoptosis of Acute Lymphoblastic Leukemia (ALL) blasts in response to chemotherapy could occur through diverse pathways including both p53-dependent and -independent mechanisms. In this study we investigated the apoptotic response in more detail by using a panel of ALL cell lines that differed in respect to p53 status. Upon exposure to a uniform stimulus, expression of apoptotic proteins, including the effector caspase-3, varied among ALL cell lines partly depending on p53 transcriptional activity and caspase-8 activation. Although the expression and contribution to apoptosis differed among known members of the apoptotic pathway, apoptosis was universally mediated by mitochondrial depolarization. The NFkappaB pathway was activated in response to chemotherapy but NFkappaB inhibition appeared to not influence chemosensitivity. This study further documents the highly variable nature of cell death programs in ALL and provides the foundation for cell death pathway modulation to improve ALL cure rates without increasing chemotherapy-related toxicity.

Annexin II mediates plasminogen-dependent matrix invasion by human monocytes: enhanced expression by macrophages

Monocytes and macrophages participate in a wide variety of host defense mechanisms. Annexin II, a fibrinolytic receptor, binds plasminogen and tissue plasminogen activator (t-PA) independently at the cell surface, thereby enhancing the catalytic efficiency of plasmin production. We demonstrated previously that annexin II on the surface of both cultured monocytoid cells and monocyte-derived macrophages promotes their ability to remodel extracellular matrix. Here, we demonstrate that human peripheral blood monocytes represent the major circulating annexin II–expressing cell. Annexin II supported t-PA–dependent generation of cell surface plasmin and the matrix-penetrating activity of human monocytes. Compared to polymorphonuclear leukocytes, monocytes supported a 12.9-fold greater rate of plasmin generation in the presence of exogenous t-PA, and this activity was largely attributable to annexin II. Likewise, anti–annexin II IgG directed against the t-PA–binding tail domain inhibited plasminogen-dependent, cytokine-directed monocyte migration through extracellular matrix. On differentiation of monocytes to macrophages, there was a 2.4-fold increase in annexin II–specific mRNA, and a 7.9-fold increase in surface annexin II. Thioglycolate-elicited peritoneal macrophages, furthermore, displayed an additional 3.8-fold increase in annexin II surface expression compared with resident cells. Thus, annexin II–mediated assembly of plasminogen and t-PA on monocyte/macrophages contributes to plasmin generation, matrix remodeling, and directed migration.

A mediator of cell surface-specific plasmin generation

It has become increasingly evident that the generation of cell surface proteases including plasmin is fundamental to a wide variety of in vivo biological processes. Cell surface receptors allow for specific controlled proteolysis, provide protection from inhibitors, and enhance catalytic efficiency. Here we describe one such receptor, annexin II, which serves as a coreceptor for tissue plasminogen activator and plasminogen and is found on a wide variety of cell types including endothelial cells, some tumor cells, monocytes and macrophages, and neuronal cells. Evidence indicates that annexin II may be crucial to the efficient generation of cell surface plasmin, endothelial cell formation of new blood vessels, and maintenance of vascular patency. Additionally, it has been shown that annexin II expression in acute promyelocytic leukemia contributes to the bleeding diathesis seen in this disease and that inhibition of annexin II may be an important mechanism in the formation of atherosclerotic plaque. Furthermore, emerging evidence reveals the importance of annexin II on the surface of monocytes and macrophages, where it may contribute to the cells' ability to degrade extracellular matrix proteins and migrate to sites of injury or inflammation.

Effect of a twice daily 0.12% chlorhexidine rinse on the oral health of a geriatric population

The inhibitory effect of a chlorhexidine rinse on gingival inflammation and plaque accumulation has been well documented. The purpose of this study was to determine whether a twice daily oral rinse with 0.12% chlorhexidine will resolve denture-associated inflammation in a geriatric population. Thirty-six subjects, average age 83 years, were randomly divided into two groups, active and control, and further stratified into three subgroups, removable partial dentures, complete overdentures and lacking a removable prosthesis. Gingival (Löe and Silness '63) and plaque (Silness and Löe '64) indexes were performed on teeth Nos 3, 9, 12, 19, 25 and 28 at baseline and at 60 days. The subjects, following baseline measurements, were required to rinse twice daily for 30 seconds with either a 15 ml solution of 0.12% chlorhexidine or a placebo and instructed to continue their normal oral hygiene routine. The data were statistically analyzed. When active and control groups were compared, either in total or within their stratified subdivisions, significant differences were observed (P less than 0.001). The active group had a 10.27% and 16.68% reduction in the gingival and plaque indexes, respectively, compared to insignificant changes in the control groups. It was concluded that although chlorhexidine proved effective in reducing inflammation and plaque scores, this reduction was not influenced by the type of prosthesis worn.