A phase 1 study to assess the absolute bioavailability, mass balance, pharmacokinetics, metabolism, and excretion of [14C]-mobocertinib, an oral inhibitor of EGFR exon 20 insertion mutations, in healthy participants.

Mobocertinib (TAK-788) is a first-in-class oral epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that received accelerated approval for the treatment of patients with non-small cell lung cancer with EGFR exon 20 insertion mutations previously treated with platinum-based chemotherapy. This phase 1, 2-period, study was conducted to assess the absolute bioavailability of mobocertinib (Period 1), as well as mass balance, pharmacokinetics, metabolism, and excretion of [14C]-mobocertinib (Period 2) in healthy adult males. In Period 1, participants received a single oral capsule dose of 160 mg mobocertinib, followed by a 15-minute intravenous infusion of 50 µg (~ 2 µCi) [14C]-mobocertinib administered from 3.75 to 4 h after the capsule dose. In Period 2, a single oral dose of 160 mg (~ 100 µCi) [14C]-mobocertinib was administered as an oral solution. The geometric mean absolute bioavailability of mobocertinib was determined to be 36.7%. After oral administration of [14C]-mobocertinib, mobocertinib and its active metabolites, AP32960 and AP32914, were minor components in plasma, accounting for only 0.275% of total plasma radioactivity as the majority of mobocertinib-related material was covalently bound to plasma proteins. The geometric mean percentage of the administered radioactive dose recovered in the urine and feces was 3.57% and 76.0%, respectively. Only 0.39% of the oral dose of [14C]-mobocertinib was recovered in the urine as mobocertinib; thus, indicating that renal excretion of unchanged drug was a very minor pathway of elimination. In both treatment periods, mobocertinib was generally safe and well-tolerated as all adverse events were Grade 1 in severity. (Trial registration number ClinicalTrials.gov NCT03811834. Registration date January 22, 2019).

A phase 2 study of mobocertinib as first-line treatment in Japanese patients with non-small cell lung cancer harboring EGFR exon 20 insertion mutations.

BACKGROUND: Mobocertinib is a novel, synthetic, orally administered tyrosine kinase inhibitor that inhibits many activated forms of epidermal growth factor receptor (EGFR), including those containing exon 20 insertion (ex20ins) mutations. This study aimed to assess the efficacy of mobocertinib in Japanese patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) harboring EGFR ex20ins mutations. METHODS: This was a phase 2, open-label study. Patients with NSCLC harboring EGFR ex20ins mutations who had not had previous systemic treatment received mobocertinib 160 mg once daily. The primary endpoint was the confirmed objective response rate. A planned interim analysis was completed for the first 14 patients with a centrally confirmed EGFR ex20ins mutation, with enrollment stopped if the number of patients with an objective response was five or fewer. RESULTS: In total, 33 patients were enrolled into the study (63.6% women; median age: 66 years). At the interim analysis, the objective response rate evaluated by a central independent review committee was 28.6% (4/14, 90% confidence interval: 10.4-54.0); therefore, enrollment was stopped for futility. In the full analysis set, the objective response rate was 18.2% (6/33, 95% confidence interval: 7.0-35.5); of the six responders, one patient (3.0%) had a complete response and five patients (15.2%) had partial responses. The most common treatment-related adverse events were diarrhea, paronychia, stomatitis, and nausea. CONCLUSION: Although study enrollment was terminated early owing to futility, our results showed modest activity of mobocertinib in Japanese patients with NSCLC with EGFR ex20ins mutations with no additional safety concerns.

Mobocertinib: Mechanism of action, clinical, and translational science.

Epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutations represent ~6%-12% of all EGFR-mutated non-small cell lung cancer (NSCLC) cases. First-, second-, and third-generation tyrosine kinase inhibitors (TKIs) have limited clinical activity against EGFR ex20ins mutations. Mobocertinib is a first-in-class oral EGFR TKI that selectively targets in-frame EGFR ex20ins mutations in NSCLC; accelerated approval in the United States was granted for the treatment of adult patients with locally advanced or metastatic NSCLC with EGFR ex20ins mutations whose disease has progressed on or after platinum-based chemotherapy. Accelerated approval was based on the results from the three-part, open-label, multicenter, pivotal phase I/II nonrandomized clinical trial (NCT02716116) that enrolled 114 patients with locally advanced or metastatic EGFR ex20ins mutation-positive NSCLC who were previously treated with platinum-based chemotherapy and received mobocertinib at the recommended dosage of 160 mg once daily. At the November 1, 2021, data cutoff date, the confirmed objective response rate per independent review committee (IRC) was 28%, median duration of response was 15.8 months, median progression-free survival per IRC was 7.3 months, and median overall survival was 20.2 months. The most common treatment-emergent adverse events were gastrointestinal- and skin-related. The phase III EXCLAIM-2 study evaluated mobocertinib versus chemotherapy as first-line therapy for locally advanced or metastatic EGFR ex20ins-positive NSCLC; however, the primary end point was not met, resulting in initiating voluntary withdrawal of mobocertinib worldwide. This mini-review article summarizes the mechanism of action, pharmacokinetic characteristics, key clinical trials, and clinical efficacy and safety data for mobocertinib.

Pevonedistat plus azacitidine vs azacitidine alone in higher-risk MDS/chronic myelomonocytic leukemia or low-blast-percentage AML.

PANTHER is a global, randomized phase 3 trial of pevonedistat+azacitidine (n = 227) vs azacitidine monotherapy (n = 227) in patients with newly diagnosed higher-risk myelodysplastic syndromes (MDS; n = 324), higher-risk chronic myelomonocytic leukemia (n = 27), or acute myeloid leukemia (AML) with 20% to 30% blasts (n = 103). The primary end point was event-free survival (EFS). In the intent-to-treat population, the median EFS was 17.7 months with pevonedistat+azacitidine vs 15.7 months with azacitidine (hazard ratio [HR], 0.968; 95% confidence interval [CI], 0.757-1.238; P = .557) and in the higher-risk MDS cohort, median EFS was 19.2 vs 15.6 months (HR, 0.887; 95% CI, 0.659-1.193; P = .431). Median overall survival (OS) in the higher-risk MDS cohort was 21.6 vs 17.5 months (HR, 0.785; P = .092), and in patients with AML with 20% to 30% blasts was 14.5 vs 14.7 months (HR, 1.107; P = .664). In a post hoc analysis, median OS in the higher-risk MDS cohort for patients receiving >3 cycles was 23.8 vs 20.6 months (P = .021) and for >6 cycles was 27.1 vs 22.5 months (P = .008). No new safety signals were identified, and the azacitidine dose intensity was maintained. Common hematologic grade ≥3 treatment emergent adverse events were anemia (33% vs 34%), neutropenia (31% vs 33%), and thrombocytopenia (30% vs 30%). These results underscore the importance of large, randomized controlled trials in these heterogeneous myeloid diseases and the value of continuing therapy for >3 cycles. The trial was registered on clinicaltrials.gov as #NCT03268954.

Measuring patient-reported physical functioning and fatigue in myelodysplastic syndromes using a modular approach based on EORTC QLQ-C30.

PURPOSE: Physical functioning and fatigue are key patient concerns in myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML). The objective of this research was to generate supportive quantitative evidence for modular physical functioning and fatigue measures based on the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30 items (QLQ-C30) and a customized selection of 10 supplemental items from the EORTC Item Library. METHODS: The 40 items were completed online cross-sectionally by 51 patients (higher risk [HR] MDS: 53%; CMML: 26%; AML: 10%). Psychometric analyses based on Rasch measurement theory (RMT) were conducted on the QLQ-C30 physical functioning and fatigue domains as well as measures combining QLQ-C30 and supplemental items. A measure of anemia-related symptoms composed of QLQ-C30 and supplemental items covering fatigue, dyspnea, and dizziness was also investigated. RESULTS: The QLQ-C30 physical functioning and fatigue domains showed good targeting to the sample and adequate reliability, with few conceptual gaps identified. Combining the QLQ-C30 and supplemental physical functioning and fatigue items improved the conceptual coverage and the reliability of the measures. The patient-reported anemia-related symptom measure showed good measurement performance, underpinned by a clinically meaningful characterization of severity of these symptoms over a spectrum, starting with fatigue, then dyspnea, and finally dizziness (most severe). CONCLUSION: The modular measurement approach of combining EORTC QLQ-C30 and Item Library offers a promising pragmatic solution to the measurement of physical functioning and fatigue, as well as anemia-related symptoms in clinical trials conducted in HR MDS, CMML, and AML.

A retrospective study evaluating treatment patterns and survival outcomes in elderly patients with acute myeloid leukemia treated in the United States with either 7+3 or a hypomethylating agent.

Intensive treatment for newly diagnosed acute myelogenous leukemia (ND-AML) patients are reserved for "fit" patients. While guidelines recommend evaluation of age, performance status and comorbidities, there is no consensus on the definition of "fitness" or optimal therapy for elderly AML patients. This retrospective study evaluated characteristics and survival outcomes of 274 patients (age ≥60 years) with ND-AML treated with 7 + 3 (cytarabine + an anthracycline) vs. hypomethylating agents (HMAs). Most patients received 7 + 3 (60.2%) vs. HMAs (39.8%) in first-line therapy (1 L T); more HMA patients were ≥75 years old and had more comorbidities. Median progression-free survival (PFS) following 1 L T was longer for patients who received 7 + 3 vs. HMAs (6.7 months [95% confidence interval (CI)]: 4.9, 11.1) vs. 4.1 months (95% CI: 2.8, 4.9, respectively). Median overall survival (OS) following 1 L T was also longer for patients who received 7 + 3 vs. HMAs (14.7 months [95% CI: 11.0, not estimated] vs. 4.3 months [95% CI: 3.2, 5.8], respectively). An age-adjusted Charlson Comorbidity Index score of ≥4 vs. < 4 negatively affected PFS and OS irrespective of treatment. Overall, choosing an HMA over 7 + 3 in elderly patients with ND-AML may be influenced by age and comorbidities; patients receiving 7 + 3 had longer survival than those on an HMA.

Transfusion-free interval is associated with improved survival in patients with higher-risk myelodysplastic syndromes engaged in routine care.

Most higher-risk myelodysplastic syndrome (HR-MDS) patients will become transfusion-dependent, leading to potential complications, including infections or end-organ dysfunction. Data correlating achievement of transfusion-free intervals (TFIs) during first-line therapy (1LT) with survival are sparse. We evaluated HR-MDS patients receiving 1LT diagnosed from 1/1/2008 to 7/31/2015 and the impact of a TFI (≥60-day interval without transfusions) on progression-free and overall survival (PFS, OS) using Cox proportional-hazard models. Two hundred and twenty-nine HR-MDS patients received 1LT; overall, median PFS/OS were 8.4 months and 14.7 months, respectively. Two-year PFS/OS were 22.3% and 34.6%, respectively. Median PFS/OS were longer for patients with vs. without a TFI (16.9 vs. 6.1 months and 26.1 vs. 11.8 months, respectively; p < .01 [both]). Two-year PFS (43.0% vs. 3.9%; p < .01) and 2-year OS (51.8% vs. 22.5%; p < .01) were also longer in patients with a TFI vs. not. Achievement of a TFI during 1LT appears to positively affect PFS and OS in HR-MDS patients.

Economic Burden of Patients Treated for Higher-Risk Myelodysplastic Syndromes (HR-MDS) in Routine Clinical Care in the United States.

BACKGROUND AND OBJECTIVE: Significant clinical burden is associated with higher-risk myelodysplastic syndromes (HR-MDS); however, the economic burden has not been fully examined. We examined cost of care and healthcare utilization (HCU) in HR-MDS patients engaged in routine care in the United States (US). METHODS: Adult US patients diagnosed with HR-MDS from 1/1/2008 to 10/31/2015 were identified from the Optum database. Patients were followed until death, progression to acute myeloid leukemia (AML), end of enrollment, or end of study (12/31/2015). Myelodysplastic syndrome (MDS)-related costs/HCU (including medical/pharmacy claims with a primary diagnosis of MDS, MDS-related treatment, or supportive care) and non-MDS-related costs/HCU were evaluated. Costs were calculated as per-patient per-month (PPPM) costs adjusted to 2015 US dollars. RESULTS: Of the 209 HR-MDS patients included, median follow-up was 9.9 months (interquartile range 4.6-17.9), and 69.4% had at least one inpatient admission, 56.9% had at least one emergency department visit, and nearly all patients had at least one outpatient visit. Average PPPM costs over follow-up were $17,361; year 1 versus year 2 costs were higher ($17,337 vs $12,976) following HR-MDS diagnosis. The majority of costs were for MDS-related medical services ($10,327 PPPM). MDS-related medical PPPM costs decreased from $10,557 (year 1) to $6530 (year 2). The main drivers of MDS-related medical costs and the decrease in year 2 were chemotherapy and supportive care costs. CONCLUSIONS: The economic burden of HR-MDS is considerable, particularly within the first year of diagnosis. Treatment/supportive care costs accounted for a significant portion of MDS-related costs. As HR-MDS treatment evolves, the economic impact and HCU need to be further investigated.

A pragmatic patient-reported outcome strategy for rare disease clinical trials: application of the EORTC item library to myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia.

BACKGROUND: Novel, pragmatic, patient-centered strategies are needed to ensure fit-for-purpose patient-reported outcomes (PRO) instruments in clinical trial research for rare diseases such as myelodysplastic syndromes (MDS), acute myeloid leukemia (AML), and chronic myelomonocytic leukemia (CMML). The objective of the current study was to select supplemental items to add to the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life-Core 30 (QLQ-C30) to ensure content coverage of all important clinical concepts in patients with higher-risk (HR) MDS, low-blast count (LB) AML, and CMML, thus, improving the instrument's ability to detect clinically meaningful treatment benefit for this context of use. METHODS: Our mixed methods approach comprised literature review, clinician consultation (n = 3), and qualitative and quantitative analysis of two stages of patient interview data (n = 14, n = 18) to select library bank items to supplement a generic cancer PRO, the EORTC QLQ-C30. RESULTS: Unique symptom (n = 54) and impact (n = 72) concepts were organized into conceptual frameworks of treatment benefit, compared with EORTC QLQ-C30 items and conceptual gaps identified. Supplemental items (n = 13) addressing those gaps were selected from the EORTC Item Library and tested with patients. Supplemental item endorsement frequencies met World Health Organization Quality of Life criteria, suggesting good targeting and relevance for this sample. However, three supplemental items were confirmed as problematic based upon cognitive debriefing results, and expert clinical consultations. Ultimately, 10 supplemental items (n = 7 symptom; n = 3 impact) were selected for the MDS/AML/CMML context. CONCLUSION: Supplemental items were selected to enhance the conceptual coverage of the EORTC QLQ-C30 in the areas of fatigue, shortness of breath, and functioning.

Effectiveness and Safety of Therapeutic Regimens for Elderly Patients With Acute Myeloid Leukemia: A Systematic Literature Review.

Acute myeloid leukemia (AML) is the second most common leukemia among adults. Although the median age at diagnosis is 67 years, with approximately one third of patients aged 75 years or older, limited treatment options exist for the elderly, who have 5-year survival rates of only 5%. A systematic review was conducted to examine effectiveness and safety outcomes of treatment regimens in elderly (≥60 years old) patients with AML. Published literature on the topic was scant, and the review included only 22 articles examining outcomes. Twelve studies examined treatment-specific outcomes; most of these examined azacitidine or intensive chemotherapy (IC). An international randomized controlled trial found that azacitidine significantly improved overall survival relative to conventional regimens including IC and low-dose cytarabine in patients aged > 65 years. Similar results in favor of azacitidine were demonstrated in 2 other studies. IC was generally associated with longer survival versus lower-intensity therapy or best supportive care. Findings suggest that azacitidine is a viable option for elderly AML patients who are ineligible for IC, and emerging agents used in combination with azacitidine could have a major impact in this difficult-to-treat population.

Systematic Literature Review of Treatment Options and Clinical Outcomes for Patients With Higher-Risk Myelodysplastic Syndromes and Chronic Myelomonocytic Leukemia.

High-dose chemotherapy with allogeneic hematopoietic stem cell transplantation (allo-HSCT) can produce long-term remission in patients with higher-risk myelodysplastic syndromes (HR-MDS) and chronic myelomonocytic leukemia (CMML). However, this treatment regimen is not appropriate for elderly and/or comorbid patients; in these cases, azacitidine is a standard treatment. This systematic review was conducted to evaluate real-world evidence of treatment options for patients with HR-MDS/CMML. Medline and Embase (January 2006 to May 2016) were searched, in addition to conference proceedings and treatment guideline reviews. Studies on clinical effectiveness/efficacy outcomes with a sample size ≥50 patients were included. From 1061 unique citations identified, 87 full-text articles were reviewed, of which 24 articles reported at least 1 outcome of interest. Studies showed that HR-MDS/CMML patients treated with a conventional chemotherapy regimen (CCR) have poorer overall survival (OS). Key findings from individual HR-MDS studies showed improved survival with azacitidine over CCRs and higher overall response rates with clofarabine relative to low-dose cytosine arabinoside (but no significant difference in 2-year OS favoring clofarabine). OS was highest for patients treated with allo-HSCT. Findings indicate limited real-world data on treatment strategies available for HR-MDS/CMML patients. Most studies address the effect of chemotherapy or allo-HSCT on clinical outcomes, so are not applicable to elderly/comorbid patients who are too frail for those treatments. In particular, our analysis revealed limited evidence on viable options after failure of treatment with azacitidine, identifying a significant unmet need in this patient population.

Economic burden of elderly patients with acute myeloid leukemia treated in routine clinical care in the United States.

This retrospective claims database study examined healthcare utilization (HCU) and costs associated with acute myeloid leukemia (AML) in 237 elderly patients who received chemotherapy or a stem cell transplant (SCT) following AML diagnosis. Patients with secondary AML were excluded. Over the entire follow-up period, 92.0% of patients had ≥1 inpatient admission; 85.7% had ≥1 AML-related admission, and 42.6% had ≥1 non-AML-related admission. During inpatient admissions, 39.2% of patients had ≥1 intensive care unit (ICU) admission, with 20.7% having ≥1 AML-related ICU admission, and 27.8% having ≥1 non-AML-related ICU admission. Total mean per-patient per-month (PPPM) costs over the follow-up period were $25,243 (SD: $21,909), with costs from Year 1 ($27,756 [SD: $22,121]) more than double those in Year 2 ($12,953 [SD: $26,334]) following AML diagnosis. The majority of total costs were medical ($24,512 PPPM [SD: $21,704]), which included inpatient admissions ($6548 PPPM [SD: $10,777]), other outpatient visits ($5021 PPPM [SD: $7997]), supportive care ($3640 PPPM [SD: $5589], and chemotherapy administration ($2029 PPPM [SD: $2345]). Healthcare costs of treated elderly AML patients are substantial, particularly in the first year following diagnosis. Further research is needed to understand factors contributing to high costs in various settings of care for elderly AML patients.

A phase I study of the dolastatin-15 analogue tasidotin (ILX651) administered intravenously daily for 5 consecutive days every 3 weeks in patients with advanced solid tumors.

PURPOSE: To determine the maximum tolerated dose, dose-limiting toxicity, and pharmacokinetics of the dolastatin-15 analogue, tasidotin (ILX651), when administered i.v. daily for 5 days every 3 weeks. EXPERIMENTAL DESIGN: Thirty-six patients with advanced solid tumors received a total of 114 courses through eight dose levels ranging from 2.3 to 36.3 mg/m(2). Pharmacokinetic samples were collected in cycle 1. RESULTS: Neutropenia was the principal dose-limiting toxicity at 36.3 mg/m(2)/d along with grade 3 ileus and elevated aspartate amino transaminase/alanine amino transaminase (n = 1). At the maximum tolerated dose, 27.3 mg/m(2), 4 of 14 patients experienced dose-limiting grade 4 neutropenia. The other principal toxicities consisted of mild-to-moderate elevated transaminases, alopecia, fatigue, and nausea. One patient with melanoma metastatic to liver and bone treated at 15.4 mg/m(2)/d experienced a complete response and received 20 courses of tasidotin. Two other patients with melanoma had mixed responses of cutaneous metastases at 27.3 mg/m(2)/d associated with either stable or progressive visceral disease. In addition, nine patients had stable disease. There was no accumulation of tasidotin following repeated daily dosing. Tasidotin decayed from plasma in a biphasic fashion with a half-life of <45 minutes in most cases. CONCLUSION: The maximum tolerated dose and recommended phase II dose for tasidotin when administered on this schedule was 27.3 mg/m(2)/d. The favorable toxicity profile of tasidotin compared with other antitubulin agents (particularly the lack of severe cumulative neuropathy, peripheral edema, and fatigue), the observed antitumor activity of tasidotin, and its novel mechanism of action support further disease-directed evaluations of this agent on this 5-day schedule every 3 weeks.

Phase I and pharmacokinetic study of the dolastatin-15 analogue tasidotin (ILX651) administered intravenously on days 1, 3, and 5 every 3 weeks in patients with advanced solid tumors.

PURPOSE: To determine the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), and pharmacokinetics of tasidotin (ILX651), a dolastatin-15 analogue, when administered on days 1, 3, and 5 every 3 weeks in patients with advanced solid tumors. PATIENTS AND METHODS: Thirty-two patients were treated with 92 courses of tasidotin through seven dose levels determined by a modified Fibonacci scheme ranging from 3.9 to 45.7 mg/m(2). Pharmacokinetic samples were collected during the first course. RESULTS: Neutropenia was the principal DLT at the 45.7 mg/m(2)/d dose level. In addition, one patient also experienced grade 3 neutropenia complicated with grade 3 esophageal candidiasis and grade 3 dehydration. Only 1 of 11 patients treated at the MTD, 34.4 mg/m(2), experienced dose-limiting neutropenia. Other common, drug-related toxicities included mild to moderate fatigue, anemia, nausea, anorexia, emesis, alopecia, and diarrhea. The best observed antitumor response consisted of stable disease and was noted in 10 patients (31%); the median duration on study for those patients with stable disease was 99.5 days compared with 37.5 days for those patients with progressive disease. Tasidotin plasma concentrations declined biphasically with an effective half-life of < or =55 minutes, and approximately 11% was excreted unchanged in the urine. CONCLUSION: The recommended dose for phase II studies and the MTD when tasidotin is administered on days 1, 3, and 5 every 3 weeks is 34.4 mg/m(2). The favorable toxicity profile of tasidotin compared with other antitubulin agents, including other dolastatin analogues, and its novel mechanism of action support further disease-directed evaluation of this agent.

Pharmacokinetics and antitumor efficacy of XMT-1001, a novel, polymeric topoisomerase I inhibitor, in mice bearing HT-29 human colon carcinoma xenografts.

PURPOSE: To evaluate the pharmacokinetics and tissue disposition of macromolecular camptothecin (CPT) drug conjugate, XMT-1001, and irinotecan (CPT-11) in mice bearing HT-29 xenograft tumors. EXPERIMENTAL DESIGN: The antitumor efficacy of XMT-1001 was evaluated in the mouse HT-29 human colon carcinoma xenograft model. XMT-1001 was administered intravenously to female athymic nude (nu/nu) mice bearing established HT-29 xenograft tumors (n = 10) at 15, 30, and 60 mg CPT equivalents/kg on weekly or biweekly schedules. The tumor growth inhibition and tumor growth delay endpoints were used for efficacy evaluation. In the pharmacokinetic study, XMT-1001 was administered intravenously at a pharmacologically relevant dose of 60 mg CPT equivalents/kg × 1 via tail vein or an equimolar dose of CPT-11 at 100 mg/kg i.p. × 1. Mice (n = 3 per time point) were euthanized from 0.083 to 336 hours after XMT-1001 administration and from 0.083 to 24 hours after CPT-11. Plasma, tumor, and tissues were collected from all animals. A liquid chromatography-tandem mass spectrometry assay was used to measure XMT-1001, conjugate release products, CPT-20-O-(N-succinimido-glycinate; CPT-SI) and CPT-20-O-(N-succinamidoyl-glycinate; CPT-SA), and CPT. RESULTS: After XMT-1001 administration, the majority of the plasma exposure is accounted for by conjugated CPT. XMT-1001 exhibited a prolonged exposure of conjugated drug, active conjugate primary release products, CPT-SI and CPT-SA, and active CPT, which was associated with greater antitumor response compared with CPT-11. CONCLUSIONS: XMT-1001 provides an extended systemic and tumor exposure of conjugated drug and shows improved antitumor effect compared with CPT-11.

XMT-1001, a novel polymeric camptothecin pro-drug in clinical development for patients with advanced cancer.

An overview of XMT-1001 is provided in the context of other topoisomerase I inhibitors conjugated to polymers or encapsulated in liposomes. XMT-1001 is a novel polymeric pro-drug derivative of camptothecin (CPT) with a molecular weight of 70 kDa, in which CPT is chemically tethered to a hydrophilic, biodegradable polyacetal polymer, poly(1-hydroxymethylethylene hydroxymethylformal), also called PHF or Fleximer(R). XMT-1001 releases CPT via intermediates camptothecin-20-O-(N-succinimidoglycinate) (CPT-SI), and camptothecin-20-O-(N-succinamidoyl-glycinate) (CPT-SA) over an extended time period. XMT-1001 has an improved therapeutic window compared to CPT and irinotecan in human tumor xenograft models, providing a compelling rationale for clinical development. A unique feature of XMT-1001 is its dual phase release mechanism for CPT which may result in lower levels of CPT in the urine and less bladder toxicity, a serious dose limiting toxicity associated with CPT and CPT conjugated to other polymers. XMT-1001 is being evaluated in patients with advanced cancer in an ongoing Phase 1 trial.