Successful treatment with selpercatinib after pralsetinib-related pneumonitis and intracranial failure in a patient with RET-rearranged nonsmall cell lung cancer.

Pralsetinib and selpercatinib are two highly potent and selective rearranged during transfection (RET) inhibitors that substantially improved the clinical outcome of patients with RET-rearranged non-small cell lung cancer. Treatment with one RET inhibitor after failure of the other is generally not recommended because of cross-resistance mechanisms. We report the case of a patient affected by metastatic RET-rearranged non-small cell lung cancer who experienced long-lasting disease control with pralsetinib. After 13 months from treatment start, the patient developed recurrent drug-related pneumonitis, requiring temporary interruptions and dose reductions and eventually failing to control the disease. Selpercatinib was then started as an off-label treatment, allowing both clinical and radiological intracranial disease control. Selpercatinib was well-tolerated at full dosage, and no pulmonary event occurred. In our case report, after pralsetinib dose reduction due to pulmonary toxicity, the therapeutic switch to selpercatinib allowed the patient to receive a full-dose treatment, eventually restoring disease control. Our case report and a few literature data suggest that switching from pralsetinib to selpercatinib may represent a therapeutic opportunity, especially for patients with brain metastases.

Safety and efficacy of zandelisib plus zanubrutinib in previously treated follicular and mantle cell lymphomas.

The combination of the phosphatidylinositol 3-kinase delta (PI3Kδ) inhibitor zandelisib with the Bruton's tyrosine kinase (BTK) inhibitor zanubrutinib was hypothesized to be synergistic and prevent resistance to single-agent therapy. This phase 1 study (NCT02914938) included a dose-finding stage in patients with relapsed/refractory (R/R) B-cell malignancies (n = 20) and disease-specific expansion cohorts in follicular lymphoma (FL; n = 31) or mantle cell lymphoma (MCL; n = 19). The recommended phase 2 dose was zandelisib 60 mg on Days 1-7 plus zanubrutinib 80 mg twice daily continuously in 28-day cycle. In the total population, the most common adverse events (AEs; all grades/grade 3-4) were neutropenia (35%/24%), diarrhoea (33%/2%), thrombocytopenia (32%/8%), anaemia (27%/8%), increased creatinine (25%/0%), contusion (21%/0%), fatigue (21%/2%), nausea (21%/2%) and increased aspartate aminotransferase (24%/6%). Three patients discontinued due to AEs. The overall response rate was 87% (complete response [CR] = 33%) for FL and 74% (CR = 47%) for MCL. The median duration of response and progression-free survival (PFS) were not reached in either group. The estimated 1-year PFS was 72.3% (95% confidence interval [CI], 51.9-85.1) for FL and 56.3% (95% CI, 28.9-76.7) for MCL (median follow-up: 16.5 and 10.9 months respectively). Zandelisib plus zanubrutinib was associated with high response rates and no increased toxicity compared to either agent alone.

Eltrombopag treatment in thrombocytopenia following hematopoietic stem cell transplantation: A multicenter real-world experience.

INTRODUCTION: Thrombocytopenia is among the most common complications following hematopoietic stem cell transplantation and is associated with increased mortality and morbidity with no standard treatment yet. In this multicenter and retrospective study, we aim to present our multi-center experience of Eltrombopag treatment in patients with isolated thrombocytopenia following HSCT. MATERIAL-METHOD: A total of 73 patients from 5 centers who underwent autologous or allogeneic stem cell transplantation, had no primary disease relapse, all of whom had neutrophil engraftment, complete chimerism, and who were diagnosed with Prolonged Isolated Thrombocytopenia (PIT) or Secondary Failure Of Platelet Recovery (SFPR) were included in the study. The patients were initiated on Eltrombopag at a dose of 50-150 mg. Complete response was defined as a platelet count >50×109/L for 7 consecutive days with no transfusion support. RESULTS: A total of 50.3% of the patients underwent Autologous and 49.7% Allogeneic Stem Cell Transplantation, 54.8% were diagnosed with PIT, and 45.2% were diagnosed with SFPR, and the treatment with 50-150 mg/day Eltrombopag was initiated on the median day +42. Complete response was achieved in 71.2% of these patients on the median day 23 of the treatment. No significant effects of the initial dose (50-150 mg/day) were detected in the Complete Response in the multivariate analysis on response. An insufficient number of Megakaryocytes in the bone marrow before Eltrombopag treatment was determined as an independent risk factor in determining the response (OR 3.57, 95% CI 1.21-10.55). The overall survival of the patients who did not respond to Eltrombopag was found to be significantly worse than that of patients who responded (p=0.022, HR:2.74, 95% CI 1.12-6.54). CONCLUSION: As a result of the present study, Eltrombopag treatment was found to be effective and safe in thrombocytopenia that develops following hematopoietic stem cell transplantation. It was concluded that its use may be more effective in patients with sufficient bone marrow megakaryocytes before the treatment and an initial dose of 50 mg/day may be appropriate in terms of cost, effectiveness, and toxicity. Large-scale randomized and controlled prospective studies are needed to determine the roles of Eltrombopag treatment in patients with post-transplant PIT and SFPR.

Drug-drug interaction potential among patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) treated with novel androgen receptor inhibitors.

BACKGROUND: Nonmetastatic castration-resistant prostate cancer (nmCRPC) patients are often older and use concurrent medications that increase the potential for drug-drug interactions (pDDIs). This study assessed pDDI prevalence in real-world nmCRPC patients treated with apalutamide, darolutamide, or enzalutamide. RESEARCH DESIGN AND METHODS: Castrated prostate cancer patients without metastases prior to androgen receptor inhibitor initiation were identified retrospectively via Optum Clinformatics Data Mart claims data (8/2019-3/2021). The top 100 concomitant medications were assessed for pDDIs. RESULTS: Among 1,515 patients (mean age: 77 ± 8 years; mean Charlson Comorbidity Index: 3 ± 3), 340 initiated apalutamide, 112 darolutamide, and 1,063 enzalutamide. Common concomitant medication classes were cardiovascular (80%) and central nervous system (52%). Two-thirds of the patients received ≥5 concomitant medications; 30 (30/100 medications) pDDIs were identified for apalutamide and enzalutamide each and 2 (2/100 medications) for darolutamide. Most pDDIs had risk ratings of C or D, but four for apalutamide were rated X. Approximately 58% of the patients on apalutamide, 5% on darolutamide, and 54% on enzalutamide had ≥1 identified pDDI. CONCLUSIONS: Results showed a higher frequency of pDDIs in patients receiving apalutamide and enzalutamide vs darolutamide. The impact of these could not be determined retrospectively. DDI risk should be carefully evaluated when discussing optimal therapy for patients with nmCRPC.

A phase II study of ibrutinib in combination with ixazomib in patients with Waldenström macroglobulinaemia.

This phase II study evaluated time-limited (24 cycles) treatment with ibrutinib and ixazomib in newly diagnosed (NDWM; n = 9) and relapsed/refractory (RRWM; n = 12) Waldenström macroglobulinaemia (WM). The overall response rate (ORR) was 76.2% (n = 16) in 21 evaluable patients with no patient achieving a complete response (CR). The median duration of treatment was 15.6 months, and after a median follow-up time of 25.7 months, the median progression-free survival (PFS) was 22.9 months. While the primary end-point was not met (CR rate at any time) and 28.5% discontinued treatment due to toxicity, ibrutinib plus ixazomib led to a clinically meaningful ORR and PFS. Combined Bruton's tyrosine kinase (BTK) and proteasome inhibition merits further evaluation in WM.

Ibrutinib plus Bendamustine and Rituximab in Untreated Mantle-Cell Lymphoma.

BACKGROUND: Ibrutinib, a Bruton's tyrosine kinase inhibitor, may have clinical benefit when administered in combination with bendamustine and rituximab and followed by rituximab maintenance therapy in older patients with untreated mantle-cell lymphoma. METHODS: We randomly assigned patients 65 years of age or older to receive ibrutinib (560 mg, administered orally once daily until disease progression or unacceptable toxic effects) or placebo, plus six cycles of bendamustine (90 mg per square meter of body-surface area) and rituximab (375 mg per square meter). Patients with an objective response (complete or partial response) received rituximab maintenance therapy, administered every 8 weeks for up to 12 additional doses. The primary end point was progression-free survival as assessed by the investigators. Overall survival and safety were also assessed. RESULTS: Among 523 patients, 261 were randomly assigned to receive ibrutinib and 262 to receive placebo. At a median follow-up of 84.7 months, the median progression-free survival was 80.6 months in the ibrutinib group and 52.9 months in the placebo group (hazard ratio for disease progression or death, 0.75; 95% confidence interval, 0.59 to 0.96; P = 0.01). The percentage of patients with a complete response was 65.5% in the ibrutinib group and 57.6% in the placebo group (P = 0.06). Overall survival was similar in the two groups. The incidence of grade 3 or 4 adverse events during treatment was 81.5% in the ibrutinib group and 77.3% in the placebo group. CONCLUSIONS: Ibrutinib treatment in combination with standard chemoimmunotherapy significantly prolonged progression-free survival. The safety profile of the combined therapy was consistent with the known profiles of the individual drugs. (Funded by Janssen Research and Development and Pharmacyclics; SHINE ClinicalTrials.gov number, NCT01776840.).

ACEA Attenuates Oxidative Stress by Promoting Mitophagy via CB1R/Nrf1/PINK1 Pathway after Subarachnoid Hemorrhage in Rats.

METHOD: Endovascular perforation was performed to establish a SAH model of rats. ACEA was administered intraperitoneally 1 h after SAH. The CB1R antagonist AM251 was injected intraperitoneally 1 h before SAH induction. Adenoassociated virus- (AAV-) Nrf1 shRNA was infused into the lateral ventricle 3 weeks before SAH induction. Neurological tests, immunofluorescence, DHE, TUNEL, Nissl staining, transmission electron microscopy (TEM), and Western blot were performed. RESULTS: The expression of CB1R, Nrf1, PINK1, Parkin, and LC3II increased and peaked at 24 h after SAH. ACEA treatment exhibited the antioxidative stress and antiapoptosis effects after SAH. In addition, ACEA treatment increased the expression of Nrf1, PINK1, Parkin, LC3II, and Bcl-xl but repressed the expression of Romo-1, Bax, and cleaved caspase-3. Moreover, the TEM results demonstrated that ACEA promoted the formation of mitophagosome and maintained the normal mitochondrial morphology of neurons. The protective effect of ACEA was reversed by AM251 and Nrf1 shRNA, respectively. CONCLUSIONS: This study demonstrated that ACEA alleviated oxidative stress and neurological dysfunction by promoting mitophagy after SAH, at least in part via the CB1R/Nrf1/PINK1 signaling pathway.

Targeting the E1 ubiquitin-activating enzyme (UBA1) improves elexacaftor/tezacaftor/ivacaftor efficacy towards F508del and rare misfolded CFTR mutants.

The advent of Trikafta (Kaftrio in Europe) (a triple-combination therapy based on two correctors-elexacaftor/tezacaftor-and the potentiator ivacaftor) has represented a revolution for the treatment of patients with cystic fibrosis (CF) carrying the most common misfolding mutation, F508del-CFTR. This therapy has proved to be of great efficacy in people homozygous for F508del-CFTR and is also useful in individuals with a single F508del allele. Nevertheless, the efficacy of this therapy needs to be improved, especially in light of the extent of its use in patients with rare class II CFTR mutations. Using CFBE41o- cells expressing F508del-CFTR, we provide mechanistic evidence that targeting the E1 ubiquitin-activating enzyme (UBA1) by TAK-243, a small molecule in clinical trials for other diseases, boosts the rescue of F508del-CFTR induced by CFTR correctors. Moreover, TAK-243 significantly increases the F508del-CFTR short-circuit current induced by elexacaftor/tezacaftor/ivacaftor in differentiated human primary airway epithelial cells, a gold standard for the pre-clinical evaluation of patients' responsiveness to pharmacological treatments. This new combinatory approach also leads to an improvement in CFTR conductance on cells expressing other rare CF-causing mutations, including N1303K, for which Trikafta is not approved. These findings show that Trikafta therapy can be improved by the addition of a drug targeting the misfolding detection machinery at the beginning of the ubiquitination cascade and may pave the way for an extension of Trikafta to low/non-responding rare misfolded CFTR mutants.

Eltrombopag for Post-Transplant Poor Graft Function in East Asian Patients.

Poor graft function (PGF) is a serious, potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation. Eltrombopag has shown multilineage responses in patients with refractory severe aplastic anemia, supporting the idea that it may improve cytopenia in patients with PGF. This retrospective, single center analysis included 8 Korean patients receiving eltrombopag for PGF. Median interval between transplant and eltrombopag treatment was 73 days, and the median duration treatment was 3.5 weeks. With median maximum daily dose of 50 mg, the time to best response was 93 days. Median hemoglobin increased from 8.2 g/dL to 10.9 g/dL, platelet from 18.5 × 109/L to 54 × 109/L, and absolute neutrophil count from 1.25 × 109/L to 3.32 × 109/L. In conclusion, eltrombopag is a good option for PGF in Korean patients, even at a lower dose compared to western patients.

Exposure-response analyses of erdafitinib in patients with locally advanced or metastatic urothelial carcinoma.

BACKGROUND: Exposure-response analyses were conducted to explore the relationship between selected efficacy and safety endpoints and serum phosphate (PO4) concentrations, a potential biomarker of efficacy and safety, in locally advanced or metastatic urothelial carcinoma patients with FGFR alterations treated with erdafitinib. METHODS: Data from two dosing regimens of erdafitinib in a phase 2 study (NCT02365597), 6 and 8-mg/day with provision for pharmacodynamically guided titration per serum PO4 levels, were analyzed using Cox proportional hazard or logistic regression models. Efficacy endpoints were overall survival (OS), progression-free survival (PFS), and objective response rate (ORR). Safety endpoints were adverse events typical for FGFR inhibitors. RESULTS: Exposure-efficacy analyses on 156 patients (6-mg = 68; 8-mg = 88) showed that patients with higher serum PO4 levels within the first 6 weeks showed better OS (hazard ratio 0.57 [95% CI 0.46-0.72] per mg/dL of PO4; p = 0.01), PFS (hazard ratio 0.80 [0.67-0.94] per mg/dL of PO4; p = 0.01), and ORR (odds ratio 1.38 [1.02-1.86] per mg/dL of PO4; p = 0.04). Exposure-safety analyses on 177 patients (6-mg = 78; 8-mg = 99) showed that the incidence of selected adverse events associated with on-target off-tumor effects significantly rose with higher PO4. CONCLUSIONS: The exploratory relationship between serum PO4 levels and efficacy/safety outcomes supported the use of pharmacodynamically guided dose titration to optimize erdafitinib's therapeutic benefit/risk ratio. CLINICAL TRIAL REGISTRATION NUMBER: NCT02365597.

A kinase inhibitor which specifically targets the ABL myristate pocket (STAMP), but unlike asciminib crosses the blood-brain barrier.

The ubiquitously expressed ABL1 and ABL2 protein kinases play many important roles in cell function. Although they have been implicated in neuron development, maintenance and signaling, there are no good tool compounds to evaluate the effects of ABL kinase inhibition in the brain. Asciminib is a recently approved drug that specifically and potently inhibits the tyrosine kinase activity of ABL1, ABL2 and that of the chimeric BCR-ABL1 oncoprotein which causes chronic myeloid leukemia. Herein we show that asciminib does not penetrate the intact blood-brain barrier (BBB) following administration to rats, which curtails its utility for assessing the in vivo effects of ABL kinase inhibition in the brain. However, we describe another specific ABL kinase inhibitor, possessing physicochemical characteristics suitable for BBB penetration, and which after administration (either i.v., i.p. or p.o.) to mice achieves substantial, pharmacologically relevant brain concentrations. This bipyridine compound (4) therefore has potential for elucidating the role of ABL kinases in the brain in non-clinical studies.

A translational model-based approach to inform the choice of the dose in phase 1 oncology trials: the case study of erdafitinib.

PURPOSE: Erdafitinib (JNJ-42756493, BALVERSA) is a tyrosine kinase inhibitor indicated for the treatment of advanced urothelial carcinoma. In this work, a translational model-based approach to inform the choice of the doses in phase 1 trials is illustrated. METHODS: A pharmacokinetic (PK) model was developed to describe the time course of erdafitinib plasma concentrations in mice and rats. Data from multiple xenograft studies in mice and rats were analyzed using the Simeoni tumor growth inhibition (TGI) model. The model parameters were used to derive a range of erdafitinib exposures that might inform the choice of the doses in oncology phase 1 trials. Conversion of exposures to doses was based on preliminary PK assessments from the first-in human (FIH) study. RESULTS: A one-compartment PK disposition model, with linear absorption and dose-dependent clearance, adequately described the PK data in both mice and rats via an allometric scaling approach. The TGI model was able to describe tumor growth dynamics, providing quantitative measurements of erdafitinib antitumor potency in mice and rats. Based on these estimates, ranges of efficacious unbound concentration were identified for erdafitinib in mice (0.642-5.364 µg/L) and rats (0.782-2.565 µg/L). Based on the FIH data, it was possible to transpose exposures into doses and doses of above 4 mg/day provided erdafitinib exposures associated with significant TGI in animals. The findings were in agreement with the results of the FIH trial, in which the first hints of clinical activities were observed at 6 mg. CONCLUSION: The successful modeling exercise of erdafitinib preclinical data showed how translational PK-PD modeling might be a tool to help to inform the choice of the doses in FIH studies.

Eltrombopag in the treatment of patients with persistent thrombocytopenia after haploidentical peripheral blood stem cell transplantation: a single-center experience.

Persistent thrombocytopenia (PT) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is associated with an increased risk of bleeding and poor survival. The exact pathogenesis underlying PT remains unclear, and its management is difficult. Here we conducted a retrospective study to evaluate the efficacy and safety of eltrombopag (EPAG) in 34 patients with PT after allo-HSCT. Seven patients suffered from prolonged isolated thrombocytopenia (PIT), and 27 had secondary failure of platelet recovery (SFPR). For most patients, the initial dose was 25 mg or 50 mg daily, then adjusted to the maximum dose of 50-100 mg per day according to the response of platelet recovery and toleration of patients. The cumulative incidence (CI) of platelet recovery to at least 20 × 109/L and 50 × 109/L without transfusion support for at least 7 days was 72.1% and 60.7%, respectively. Nineteen (86.4%) of 22 responders were able to taper off the medication; furthermore, the platelet counts remained stable 1 month after withdrawal of EPAG. Although two patients discontinued EPAG during treatment due to headache and nausea, no patients developed grade 3 or 4 toxicities. Hypoplasia of bone marrow and decreased megakaryocytes (MKs) were found to be risk factors for overall response (OR) and complete response (CR) in multivariate analysis, respectively. Overall, our results indicated that EPAG can be used in the treatment of PT and that continuous exposure to EPAG may not be necessary.

Evaluation of the absolute oral bioavailability of the anaplastic lymphoma kinase/c-ROS oncogene 1 kinase inhibitor lorlatinib in healthy participants.

PURPOSE: Lorlatinib is a third-generation tyrosine kinase inhibitor currently approved for the treatment of anaplastic lymphoma kinase (ALK)-positive metastatic non-small cell lung cancer. This open-label, phase 1, randomized two-sequence, two-treatment, two-period, crossover study investigated the absolute oral bioavailability of lorlatinib in healthy participants. METHODS: Eligible participants were randomized to receive two treatments in one of two sequences: lorlatinib 100 mg single oral dose followed by lorlatinib 50 mg intravenous (IV) dose, or lorlatinib IV dose followed by lorlatinib oral dose, each with at least a 10-day washout between successive lorlatinib doses. Blood samples for pharmacokinetics were collected for up to 144 hours (h) after dosing. Validated liquid chromatographic-tandem mass spectrometry was used to determine plasma concentrations of lorlatinib and its benzoic acid metabolite PF-06895751. RESULTS: In total, 11 participants were enrolled (mean age 37.6 years, all male). The adjusted geometric mean (90% confidence interval) for the absolute oral bioavailability was 80.78% (75.73-86.16%). Using non-compartmental analysis, the estimated arithmetic mean elimination plasma half-life of lorlatinib was 25.5 and 27.0 h after the oral and IV doses, respectively. No deaths, serious adverse events (AEs), or severe AEs were reported, and most treatment-emergent AEs were mild in severity, with two events of transaminase increase of moderate severity. All treatment-emergent AEs were resolved by the end of the study. CONCLUSION: Both oral and IV lorlatinib were well-tolerated in healthy participants and oral lorlatinib is highly bioavailable after oral administration.

Futibatinib, an Irreversible FGFR1-4 Inhibitor, in Patients with Advanced Solid Tumors Harboring FGF/FGFR Aberrations: A Phase I Dose-Expansion Study.

Futibatinib, a highly selective, irreversible FGFR1-4 inhibitor, was evaluated in a large multihistology phase I dose-expansion trial that enrolled 197 patients with advanced solid tumors. Futibatinib demonstrated an objective response rate (ORR) of 13.7%, with responses in a broad spectrum of tumors (cholangiocarcinoma and gastric, urothelial, central nervous system, head and neck, and breast cancer) bearing both known and previously uncharacterized FGFR1-3 aberrations. The greatest activity was observed in FGFR2 fusion/rearrangement-positive intrahepatic cholangiocarcinoma (ORR, 25.4%). Some patients with acquired resistance to a prior FGFR inhibitor also experienced responses with futibatinib. Futibatinib demonstrated a manageable safety profile. The most common treatment-emergent adverse events were hyperphosphatemia (81.2%), diarrhea (33.5%), and nausea (30.4%). These results formed the basis for ongoing futibatinib phase II/III trials and demonstrate the potential of genomically selected early-phase trials to help identify molecular subsets likely to benefit from targeted therapy. SIGNIFICANCE: This phase I dose-expansion trial demonstrated clinical activity and tolerability of the irreversible FGFR1-4 inhibitor futibatinib across a broad spectrum of FGFR-aberrant tumors. These results formed the rationale for ongoing phase II/III futibatinib trials in cholangiocarcinoma, breast cancer, gastroesophageal cancer, and a genomically selected disease-agnostic population.This article is highlighted in the In This Issue feature, p. 275.

Eltrombopag Add-on Treatment in a Child With Fanconi Aplastic Anemia Awaiting Hematopoietic Stem Cell Transplantation.

Fanconi aplastic anemia (FAA) is a rare inherited bone marrow failure disorder characterized by congenital defects and pancytopenia. Hematopoietic stem cell transplantation (HSCT) is a curative treatment for patients with FAA due to the risk of cancer and pancytopenia. Blood transfusions are the best supportive therapy. Oxymetholone (5 mg/kg daily) is most commonly used; however, it is not curative. Extensive transfusions should be avoided because of alloimmunization and graft-versus-host disease because they have poor outcomes in patients with HSCT. This is a case report of a 5-year-old Syrian male patient with FAA, who was successfully treated with eltrombopag (50 mg daily) in conjunction with oxymetholone (5 mg/kg daily). The patient required platelet transfusions despite oxymetholone therapy and there was no suitable donor for HSCT. After the addition of eltrombopag therapy, platelet transfusions were no longer required. Eltrombopag can be effectively used as a bridge to HSCT in patients with FAA.

Estimating Long-Term Survival Outcomes for Tumor-Agnostic Therapies: Larotrectinib Case Study.

BACKGROUND: Larotrectinib is a precision oncology treatment for solid tumors with neurotrophic tyrosine receptor kinase (NTRK) gene fusions. Larotrectinib efficacy has been evaluated in single-arm basket trials with limited follow-up and sample sizes at the initial regulatory approval due to the rarity of solid tumors with NTRK gene fusion. OBJECTIVES: We aim to demonstrate that trends in progression-free survival (PFS) and overall survival (OS) in survival data with longer follow-up may be predicted from long-term survival estimates from survival data with shorter follow-up, including predictions for median survival when it is not observed in the trial. METHODS: Patient-level data were pooled from 3 clinical trials (NCT02122913, NCT02576431, and NCT02637687) using the 2018 and 2020 data cuts for the same subset of pediatric and adult patients. The Weibull distribution was selected for survival models. Survival predictions using 2018 data were compared to 2020 Kaplan-Meier (KM) curves. RESULTS: A total of 102 patients representing 15 tumor types were included in the analysis, with a mean age of 37 years. When comparing PFS from the 2018 survival prediction to observed 2020 KM data, the 12-month PFS rate was identical (66.6%). The 36-month PFS rate was lower for the 2018 prediction (35.3%) compared to 2020 KM data (44.4%). The median OS had not yet been reached in either data cut but was predicted to be 90 months using the 2018 data. When comparing OS from the 2018 survival prediction to the observed 2020 KM data, the 12-month OS rate was 89.0% and 86.6% and the 48-month OS rate was 67.2% and 63.0%, respectively. CONCLUSION: Long-term PFS predictions deviated from observed PFS rates due to response differences across tumor types and heavy censoring towards the end of the survival curve. However, for OS, the 48-month survival prediction was consistent with the observed 2020 KM estimate.

Rifampin and ritonavir increase oral availability and elacridar enhances overall exposure and brain accumulation of the NTRK inhibitor larotrectinib.

INTRODUCTION: Larotrectinib is an FDA-approved oral small-molecule inhibitor for neurotrophic tropomyosin receptor kinase (NTRK) fusion-positive cancer treatment. Here larotrectinib pharmacokinetic behavior upon co-administration with prototypical inhibitors of the efflux transporters ABCB1/ABCG2 (elacridar), the SLCO1A/1B (OATP1A/1B) uptake transporters (rifampin), and the drug-metabolizing enzyme CYP3A (ritonavir), respectively, was investigated. METHODS: Inhibitors were orally administered prior to oral larotrectinib (10 mg/kg) to relevant genetically modified mouse models. Larotrectinib plasma and tissue homogenate concentrations were measured by a liquid chromatography-tandem mass spectrometric assay. RESULTS: Elacridar increased oral availability (2.7-fold) and markedly improved brain-to-plasma ratios (5.0-fold) of larotrectinib in wild-type mice. Mouse (m)Oatp1a/1b but not hepatic transgenic human (h)OATP1B1 or -1B3 restricted larotrectinib oral availability and affected its tissue distribution. Rifampin enhanced larotrectinib oral availability not only in wild-type mice (1.9-fold), but surprisingly also in Slco1a/1b-/- mice (1.7-fold). Similarly, ritonavir increased the larotrectinib plasma exposure in both wild-type (1.5-fold) and Cyp3a-/- mice (1.7-fold). Intriguingly, both rifampin and ritonavir decreased liver and/or intestinal larotrectinib levels in all related experimental groups, suggesting additional inhibition of enterohepatic Abcb1a/1b activity. CONCLUSIONS: Elacridar enhances both larotrectinib plasma and tissue exposure and especially relative brain penetration, which might be therapeutically relevant. Hepatic mOatp1a/1b but not hOATP1B1 or -1B3 transported larotrectinib. Additionally, rifampin enhances larotrectinib systemic exposure, most likely by inhibiting mOatp1a/1b, but probably also hepatic and/or intestinal mAbcb1. Similar to rifampin, dual-inhibition functions of ritonavir affecting both CYP3A enzymes and enterohepatic Abcb1 transporters enhanced larotrectinib oral availability. The obtained insights may be used to further optimize the clinical-therapeutic application of larotrectinib.

Updated recommendations on the use of ruxolitinib for the treatment of myelofibrosis.

OBJECTIVES: Myelofibrosis is a rare bone marrow disorder associated with a high symptom burden, poor prognosis, and shortened survival. While allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment for myelofibrosis, the only approved and reimbursed pharmacotherapy for non-HSCT candidates in Belgium is ruxolitinib. METHODS: These updated recommendations are based on a consensus reached during two meetings and provide guidance for ruxolitinib administration in myelofibrosis patients considering the particularities of Belgian reimbursement criteria. RESULTS AND DISCUSSION: In Belgium, ruxolitinib is indicated and reimbursed for transplant-ineligible myelofibrosis patients from intermediate-2- and high-risk groups and from the intermediate-1-risk group with splenomegaly. Our recommendation is to also make ruxolitinib available in the pre-transplant setting for myelofibrosis patients with splenomegaly or heavy symptom burden. Before ruxolitinib initiation, complete blood cell counts are recommended, and the decision on the optimal dosage should be based on platelet count and clinical parameters. In anemic patients, we recommend starting doses of ruxolitinib of 10 mg twice daily for 12 weeks and we propose the use of erythropoiesis-stimulating agents in patients with endogenous erythropoietin levels ≤500 mU/mL. Increased vigilance for opportunistic infections and second primary malignancies is needed in ruxolitinib-treated myelofibrosis patients. Ruxolitinib treatment should be continued as long as there is clinical benefit (reduced splenomegaly or symptoms), and we recommend progressive dose tapering when stopping ruxolitinib. CONCLUSION: Based on new data and clinical experience, the panel of experts discussed ruxolitinib treatment in Belgian myelofibrosis patients with a focus on dose optimization/monitoring, adverse events, and interruption/rechallenge management.