Clinical and biological landscape of constitutional mismatch-repair deficiency syndrome: an International Replication Repair Deficiency Consortium cohort study.

BACKGROUND: Constitutional mismatch repair deficiency (CMMRD) syndrome is a rare and aggressive cancer predisposition syndrome. Because a scarcity of data on this condition contributes to management challenges and poor outcomes, we aimed to describe the clinical spectrum, cancer biology, and impact of genetics on patient survival in CMMRD. METHODS: In this cohort study, we collected cross-sectional and longitudinal data on all patients with CMMRD, with no age limits, registered with the International Replication Repair Deficiency Consortium (IRRDC) across more than 50 countries. Clinical data were extracted from the IRRDC database, medical records, and physician-completed case record forms. The primary objective was to describe the clinical features, cancer spectrum, and biology of the condition. Secondary objectives included estimations of cancer incidence and of the impact of the specific mismatch-repair gene and genotype on cancer onset and survival, including after cancer surveillance and immunotherapy interventions. FINDINGS: We analysed data from 201 patients (103 males, 98 females) enrolled between June 5, 2007 and Sept 9, 2022. Median age at diagnosis of CMMRD or a related cancer was 8·9 years (IQR 5·9-12·6), and median follow-up from diagnosis was 7·2 years (3·6-14·8). Endogamy among minorities and closed communities contributed to high homozygosity within countries with low consanguinity. Frequent dermatological manifestations (117 [93%] of 126 patients with complete data) led to a clinical overlap with neurofibromatosis type 1 (35 [28%] of 126). 339 cancers were reported in 194 (97%) of 201 patients. The cumulative cancer incidence by age 18 years was 90% (95% CI 80-99). Median time between cancer diagnoses for patients with more than one cancer was 1·9 years (IQR 0·8-3·9). Neoplasms developed in 15 organs and included early-onset adult cancers. CNS tumours were the most frequent (173 [51%] cancers), followed by gastrointestinal (75 [22%]), haematological (61 [18%]), and other cancer types (30 [9%]). Patients with CNS tumours had the poorest overall survival rates (39% [95% CI 30-52] at 10 years from diagnosis; log-rank p<0·0001 across four cancer types), followed by those with haematological cancers (67% [55-82]), gastrointestinal cancers (89% [81-97]), and other solid tumours (96% [88-100]). All cancers showed high mutation and microsatellite indel burdens, and pathognomonic mutational signatures. MLH1 or MSH2 variants caused earlier cancer onset than PMS2 or MSH6 variants, and inferior survival (overall survival at age 15 years 63% [95% CI 55-73] for PMS2, 49% [35-68] for MSH6, 19% [6-66] for MLH1, and 0% for MSH2; p<0·0001). Frameshift or truncating variants within the same gene caused earlier cancers and inferior outcomes compared with missense variants (p<0·0001). The greater deleterious effects of MLH1 and MSH2 variants as compared with PMS2 and MSH6 variants persisted despite overall improvements in survival after surveillance or immune checkpoint inhibitor interventions. INTERPRETATION: The very high cancer burden and unique genomic landscape of CMMRD highlight the benefit of comprehensive assays in timely diagnosis and precision approaches toward surveillance and immunotherapy. These data will guide the clinical management of children and patients who survive into adulthood with CMMRD. FUNDING: The Canadian Institutes for Health Research, Stand Up to Cancer, Children's Oncology Group National Cancer Institute Community Oncology Research Program, Canadian Cancer Society, Brain Canada, The V Foundation for Cancer Research, BioCanRx, Harry and Agnieszka Hall, Meagan's Walk, BRAINchild Canada, The LivWise Foundation, St Baldrick Foundation, Hold'em for Life, and Garron Family Cancer Center.

Malignant A-to-I RNA editing by ADAR1 drives T cell acute lymphoblastic leukemia relapse via attenuating dsRNA sensing.

Leukemia-initiating cells (LICs) are regarded as the origin of leukemia relapse and therapeutic resistance. Identifying direct stemness determinants that fuel LIC self-renewal is critical for developing targeted approaches. Here, we show that the RNA-editing enzyme ADAR1 is a crucial stemness factor that promotes LIC self-renewal by attenuating aberrant double-stranded RNA (dsRNA) sensing. Elevated adenosine-to-inosine editing is a common attribute of relapsed T cell acute lymphoblastic leukemia (T-ALL) regardless of molecular subtype. Consequently, knockdown of ADAR1 severely inhibits LIC self-renewal capacity and prolongs survival in T-ALL patient-derived xenograft models. Mechanistically, ADAR1 directs hyper-editing of immunogenic dsRNA to avoid detection by the innate immune sensor melanoma differentiation-associated protein 5 (MDA5). Moreover, we uncover that the cell-intrinsic level of MDA5 dictates the dependency on the ADAR1-MDA5 axis in T-ALL. Collectively, our results show that ADAR1 functions as a self-renewal factor that limits the sensing of endogenous dsRNA. Thus, targeting ADAR1 presents an effective therapeutic strategy for eliminating T-ALL LICs.

Malignant A-to-I RNA editing by ADAR1 drives T-cell acute lymphoblastic leukemia relapse via attenuating dsRNA sensing.

Leukemia initiating cells (LICs) are regarded as the origin of leukemia relapse and therapeutic resistance. Identifying direct stemness determinants that fuel LIC self-renewal is critical for developing targeted approaches to eliminate LICs and prevent relapse. Here, we show that the RNA editing enzyme ADAR1 is a crucial stemness factor that promotes LIC self-renewal by attenuating aberrant double-stranded RNA (dsRNA) sensing. Elevated adenosine-to-inosine (A-to-I) editing is a common attribute of relapsed T-ALL regardless of molecular subtypes. Consequently, knockdown of ADAR1 severely inhibits LIC self-renewal capacity and prolongs survival in T-ALL PDX models. Mechanistically, ADAR1 directs hyper-editing of immunogenic dsRNA and retains unedited nuclear dsRNA to avoid detection by the innate immune sensor MDA5. Moreover, we uncovered that the cell intrinsic level of MDA5 dictates the dependency on ADAR1-MDA5 axis in T-ALL. Collectively, our results show that ADAR1 functions as a self-renewal factor that limits the sensing of endogenous dsRNA. Thus, targeting ADAR1 presents a safe and effective therapeutic strategy for eliminating T-ALL LICs.

Unmet Needs, Barriers, and Facilitators for Conducting Adolescent and Young Adult Cancer Survivorship Research in Southern California: A Delphi Survey.

Introduction: An adolescent and young adult cancer (AYAC) patient is an individual who has received a cancer diagnosis between 15 and 39 years of age. They require significant survivorship care due to a combination of practical, physical, and mental health problems, but research in these areas is sparse. This study aimed to identify the unmet needs, barriers, and facilitators for conducting AYAC survivorship research in Southern California (SoCal) from the providers' and researchers' perspectives. Methods: A two-round, electronically administered Delphi survey study was conducted, involving a panel of 12 health care professionals and/or researchers with substantial work experience in AYAC. A 10-point Likert scale was used to evaluate 24 areas of unmet needs in AYAC survivors, 39 barriers, and 25 facilitators. Results: The top unmet needs in AYAC survivorship requiring research were in mental health issues, improving school/occupational performance, neurocognitive disorders, subsequent malignant neoplasms, and reproductive health. The top barriers identified were as follows: (1) institutions are too short-staffed to administer survivorship studies; (2) oncologists do not have the time/resources; and (3) lack of available funding. The top facilitators identified were as follows: (1) development of a mechanism/program to fund AYAC survivorship research studies; (2) in-person or virtual investigator engagement between children's hospitals and adult cancer centers to discuss research studies; and (3) developing personalized survivorship goals with AYAC patients and survivors to facilitate enrollment into survivorship studies. Conclusion: Experts identified the lack of time, manpower, funding, and resources as major barriers in AYAC survivorship research. Enhancing communication and collaboration with different stakeholders may facilitate AYAC survivorship research efforts within the SoCal region.

Tumor Genomic Profiling and Ex Vivo Drug Sensitivity Testing for Pediatric Leukemia and Lymphoma Patients.

OBJECTIVE: To describe the frequency of use of tumor genomic profiling and functional ex vivo drug sensitivity testing in pediatric patients with hematologic malignancies at our institution, and to determine how the results affected treatment selection. METHODS: A retrospective chart review was conducted to analyze the frequency of tumor genomic profiling and functional drug sensitivity screening in our institution in pediatric patients with hematologic malignancies and to ask if the results were used to direct treatment. A case series of patients for whom these testing recommendations resulted in therapeutic interventions is reported. RESULTS: Thirty-three patients underwent tumor genomic profiling assays, functional ex vivo testing, or both. Nineteen patients (58%) had genomic profiling assays performed alone, 3 (9%) had functional ex vivo testing performed alone, and 11 (33%) had both tests performed. Twenty-one (64%) patients had potentially actionable mutations detected by the genomic profiling assay. Seven (21%) patients received at least 1 chemotherapeutic agent in accordance with the tumor genomic profiling or functional ex vivo drug sensitivity testing results. Three (43%) of the 7 patients who were treated with testing directed therapy had a favorable treatment response (PR or CR) to treatments selected based upon results of genomic or functional ex vivo testing. CONCLUSIONS: This retrospective case series demonstrates that precision medicine techniques such as genomic profiling and drug sensitivity testing can positively inform treatment selection in pediatric patients with relapsed or refractory leukemia and lymphoma.

Improving vitamin D testing and supplementation in children with newly diagnosed cancer: A quality improvement initiative at Rady Children's Hospital San Diego.

BACKGROUND: Vitamin D deficiency and insufficiency have been associated with poorer health outcomes. Children with cancer are at high risk for vitamin D deficiency and insufficiency. At our institution, we identified high variability in vitamin D testing and supplementation in this population. Of those tested, 65% were vitamin D deficient/insufficient. We conducted a quality improvement (QI) initiative with aim to improve vitamin D testing and supplementation among children aged 2-18 years with newly diagnosed cancer to ≥80% over 6 months. METHODS: An inter-professional team reviewed baseline data, then developed and implemented interventions using Plan-Do-Study-Act (PDSA) cycles. Barriers were identified using QI tools, including lack of automated triggers for testing and inconsistent supplementation criteria and follow-up testing post supplementation. Interventions included an institutional vitamin D guideline, clinical decision-making tree for vitamin D deficiency, insufficiency and sufficiency, electronic medical record triggers, and automated testing options. RESULTS: Baseline: N = 26 patients, four (15%) had baseline vitamin D testing; two (8%) received appropriate supplementation. Postintervention: N = 33 patients; 32 (97%) had baseline vitamin D testing; 33 (100%) received appropriate supplementation and completed follow-up testing timely (6-8 weeks post supplementation). Change was sustained over 24 months. CONCLUSIONS: We achieved and sustained our aim for vitamin D testing and supplementation in children with newly diagnosed cancer through inter-professional collaboration of hematology/oncology, endocrinology, hospital medicine, pharmacy, nursing, and information technology. Future PDSA cycles will address patient compliance with vitamin D supplementation and impact on patients' vitamin D levels.

To test or not to test: genetic cancer predisposition testing in paediatric patients with cancer.

Genetic cancer predisposition testing in the paediatric population poses unique ethical dilemmas. Using the hypothetical example of a teenager with cancer with a high probability of having an underlying cancer predisposition syndrome, we discuss the ethical considerations that affect the decision-making process. Because legally these decisions are made by parents, genetic testing in paediatrics can remove a child's autonomy to preserve his or her own 'open future'. However, knowledge of results confirming a predisposition syndrome can potentially be beneficial in modifying treatment and surveillance plans and enabling at-risk family members to obtain cascade testing for themselves. Considering virtue ethics to envision the best characters of the patient, parents and healthcare providers can guide them to the better choice to test or not to test, with the ultimate goal of achieving the best outcome for survival and eudaimonia, human flourishing reliably sought out.

Population pharmacokinetic analysis of high-dose methotrexate in pediatric and adult oncology patients.

PURPOSE: High-dose methotrexate (HD-MTX) is widely used in pediatric and adult oncology treatment regimens. This study aimed to develop a population pharmacokinetic model to characterize pediatric and adult MTX exposure across various disease types and dosing regimens, and to evaluate exposure-toxicity relationships. METHODS: MTX pharmacokinetic data from pediatric and adult patients were collected. A population pharmacokinetic model was developed to determine the effects of age, liver function, renal function, and demographics on MTX disposition. The final model was used in Monte Carlo simulations to generate expected exposures for different dosing regimens. The association of toxicity, determined through chart review, and MTX area under the curve (AUC) was modeled using logistic regression. RESULTS: The analysis included 5116 MTX concentrations from 320 patients (135 adult, age 19-79 years; 185 pediatric, age 0.6-19 years). Estimated glomerular filtration rate (eGFR) and treatment cycle number were independent predictors of clearance (CL). CL varied 2.1-fold over the range of study eGFR values and increased 14% for treatment cycle numbers greater than 7. Higher MTX AUC was associated with higher risk of nephrotoxicity in adults, and neurotoxicity and hepatotoxicity in pediatrics. CONCLUSIONS: This study represents one of the most comprehensive evaluations of HD-MTX PK across a wide range of ages and disease types. After accounting for differences in renal function, age did not impact CL, although toxicity patterns differed by age. The model allows for early identification of patients with slowed MTX clearance and at higher risk of toxicity.

'I just need an opiate refill to get me through the weekend'.

In this article, we discuss the ethical dimensions for the prescribing behaviours of opioids for a chronic pain patient, a scenario commonly witnessed by many physicians. The opioid epidemic in the USA and Canada is well known, existing since the late 1990s, and individuals are suffering and dying as a result of the easy availability of prescription opioids. More recently, this problem has been seen outside of North America affecting individuals at similar rates in Australia and Europe. We argue that physicians are also confronted with an ethical crisis where a capitalist-consumerist society is contributing to this opioid crisis in which societal, legal and business interests push physicians to overprescribe opioids. Individual physicians often find themselves unequipped and unsupported in attempts to curb the prescribing of opioid medications and balance competing goals of alleviating pain against the judicious use of pain medications. Physicians, individually and as a community, must reclaim the ethical mantle of our profession, through a more nuanced understanding of autonomy and beneficence. Furthermore, physicians and the medical community at large have a fiduciary duty to patients and society to play a more active role in curbing the widespread distribution of opioids in our communities.

MLL rearranged acute lymphoblastic leukaemia presenting as a maxillary sinus mass with a discordant immunophenotypic profile from the bone marrow.

We describe an unusual case of pre-B lymphoblastic leukaemia presenting with a unilateral maxillary sinus mass in which biopsies of the primary mass and the bone marrow demonstrated conflicting immunophenotyping results. The extramedullary mass was consistent with a precursor B-cell malignancy, while the bone marrow was initially reported as a possible mature B-cell malignancy. The treatments for the two are fundamentally different, which necessitated a delay in the initiation of his chemotherapy until a clear diagnosis was made. Mixed lineage leukaemia gene rearrangement was confirmed by fluorescence in situ hybridisation in both the primary mass and bone marrow, which unified the diagnosis as pre-B acute lymphoblastic leukaemia given the common cytogenetic feature.

Deep Vein Thrombosis in a Young, Healthy Baseball Catcher: A Case Report and Review of the Literature.

Venous thromboembolism is becoming increasingly recognized as a significant cause of morbidity and mortality in the hospitalized pediatric population. However, young healthy athletes can present with unique risk factors for deep vein thrombosis (DVT) that can be overlooked. Here we report a case of an adolescent male with no inherited risk factors or prior history of DVTs who developed a right femoral vein DVT in the context of playing catcher in baseball after recovering from a bout of streptococcal pharyngitis. We review the evidence that suggests that repetitive squatting-induced compression of the femoral vein can cause the venous stasis and endothelial microtrauma that contributed to the formation of this thrombus.

Severe Neuropathic Pain With Concomitant Administration of Vincristine and Posaconazole.

Vincristine is a chemotherapeutic agent with a potential toxicity of sensorimotor peripheral neuropathy. Patients receiving chemotherapy are in an immunocompromised state and may require antifungal agents. Triazole antifungals are known inhibitors of cytochrome P450 (CYP) enzymes. Vincristine is a known CYP3A4 and CYP3A5 substrate, and concomitant administration with fluconazole or voriconazole has been reported to increase vincristine toxicity and peripheral neuropathy, but there is limited literature on posaconazole in this regard. This 5-year-old girl with pre-B-cell acute lymphoblastic leukemia received vincristine while receiving posaconazole for a mucormycosis infection and developed unexpectedly severe peripheral neuropathy. After recovery, the child continued on mucormycosis prophylaxis with posaconazole with instructions to hold for 2 days before and on the day of vincristine administration. This case illustrates the potentiating effect that posaconazole had on vincristine-associated neurotoxicity, and our approach to mitigating that negative interaction.

Challenges of assessing response to therapy in non-Hodgkin's lymphoma of the bone.

A 17-year-old male adolescent was diagnosed with diffuse large B cell lymphoma arising from the right humeral head. The lymphoma was found to be isolated to the bone, with a very small extraosseous component. After completion of a standard chemotherapy regimen, the Positron Emission Tomography-Computed Tomography (PET-CT) became PET negative but the CT and MRI appeared mostly unchanged in appearance, suggesting refractory disease. Repeat biopsy confirmed that no lymphoma remained, and he was in complete remission. Three months after completion of therapy, MRI continued to be abnormal. This case illustrates the unique challenges posed by the imaging characteristics of bone lymphoma, both during and after therapy. Biopsy is definitive but causes additional morbidity and may not be necessary. Imaging is done routinely to assess response to therapy, as with this patient, but in lymphomas of the bone imaging can be misleading and can lead to unnecessary procedures or follow-up imaging.

Incidentally Detected Transfusion-associated Iron Overload in 3 Children After Cancer Chemotherapy.

Iron overload is a potential long-term complication among cancer survivors who received transfusions during treatment. Although there are screening guidelines for iron overload in pediatric survivors of hematopoietic stem cell transplant, these do not call for screening of other pediatric oncology patients. In our practice we incidentally discovered 3 patients in a population of 168 cancer survivors over the span of 17 years who were treated for cancer without hematopoietic stem cell transplant who had iron overload. The 3 patients had elevated liver iron on magnetic resonance imaging T2* and 2 received therapeutic phlebotomy. These cases, and others like them, suggest that collaborative groups should consider revisiting the literature to establish screening and treatment guidelines for iron overload after cancer therapy.

Terson Syndrome Before Induction Chemotherapy for Acute Lymphoblastic Leukemia.

A previously healthy 2-year-old female infant presented with pancytopenia and was diagnosed with acute lymphoblastic leukemia. Before the initiation of treatment, she developed symptoms concerning for increased intracranial pressure. Head imaging revealed left parietal hemorrhage, in addition to a right vitreous hemorrhage, which was confirmed on ophthalmology examination later. Terson syndrome, in which intraocular hemorrhage is associated with intracranial hemorrhage, is more commonly reported in adults, although ocular manifestations of leukemia have been reported at presentation and are typically asymptomatic.

Multimodal Treatment of Rhinocerebral Mucormycosis in a Pediatric Patient With Relapsed Pre-B Acute Lymphoblastic Leukemia.

A 17-year-old girl developed invasive rhinocerebral mucormycosis during intensive re-induction chemotherapy for relapsed pre-B acute lymphoblastic leukemia. Due to the high case fatality rate for invasive mucormycosis in profoundly immunosuppressed patients, an aggressive treatment regimen was pursued. In addition to the standard of care treatments with intravenous amphotericin and aggressive surgical debridements, she received intraventricular amphotericin to the brain via an Ommaya reservoir, hyperbaric oxygen treatments, filgrastim, intravenous immunoglobulin and antifungal in vitro synergy testing to allow for more targeted antifungal therapy with the addition of micafungin. After a 3-month treatment course, it was determined that her mucormycosis was under appropriate control, allowing her to continue treatment for her leukemia with hematopoietic stem cell transplant with a plan for continued intravenous antifungal therapy through engraftment.