Pralatrexate In Combination Research Articles

Pralatrexate injection combined with CHOP for treatment of PTCL: results from the Fol-CHOP dose-finding phase 1 trial

AbstractPralatrexate is a folate antagonist that selectively enters cells expressing reduced folate carrier type 1 and competitively inhibits dihydrofolate reductase, leading to interruption of RNA synthesis, DNA replication, and apoptosis. This phase 1 study was conducted to evaluate the maximum tolerated dose (MTD) of pralatrexate in combination with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) regimen (part 1) and the response and pharmacokinetics of 6 cycles of this combination (CHOP + Folotyn 30 mg/m2 [Fol-CHOP]) in patients with newly diagnosed peripheral T-cell lymphoma (PTCL). In part 1, on days 1 and 8 of each cycle, patients were treated with 10, 15, 20, 25, or 30 mg/m2 of pralatrexate in combination with CHOP, per dose escalation, in 5 sequential cohorts. No patients experienced DLTs in cohorts 1, 2, 3, 4, and 5. The pralatrexate dose of 30 mg/m2 was selected to be combined with CHOP for part 2 and administered to 33 additional patients in the expansion cohort. At the MTD, the Fol-CHOP regimen was generally well tolerated in patients with PTCL, with an overall response rate (ORR) of 83.9% (20 complete response and 6 partial response), as assessed by treating investigators. Thirty-five patients (67.3%) experienced grade 3/4 treatment-emergent adverse events, the most common of which were anemia (21.2%), neutropenia (19.2%), febrile neutropenia (11.5%), fatigue, mucosal inflammation, nausea, and vomiting (7.7% each). In conclusion, Fol-CHOP was found to be a safe and effective treatment for newly diagnosed PTCL and deemed worthy of further investigation. This trial was registered at www.ClinicalTrials.gov as #NCT02594267.

Pralatrexate in Combination with Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone (CHOP) in Previously Untreated Patients with Peripheral T-Cell Lymphoma (PTCL): A Phase 1 Dose-Escalation Study

Background: The prognosis of patients with PTCL remains poor after standard CHOP therapy - the most commonly used combination regimen. Relapses occur in the majority of patients, and curability rates of the relapsed disease are very low. Hence, advances in front-line therapy of PTCL are long overdue. Pralatrexate, a second-generation antifolate, demonstrated a single agent activity in patients with relapsed and refractory PTCL with a response rate of 27%, including complete remissions in 11% of patients (O'Connor et al. J Clin Onc 2011). We conducted a Phase 1 multi-center dose-escalation study of pralatrexate in combination with standard CHOP (Fol-CHOP) in treatment-naïve PTCL patients.Objectives: The primary objective of the study was to determine the maximum tolerated dose (MTD) of pralatrexate when administered with a standard CHOP regimen to patients with newly diagnosed PTCL. The secondary objectives included safety, tolerability, efficacy and pharmacokinetics of pralatrexate in combination with CHOP (Fol-CHOP).Methods: In Part 1 of this 3+3 dose-escalation study, pralatrexate was administered at 10, 15, 20, 25, or 30 mg/m2 as an IV push on days 1 and 8 of a standard 21-day CHOP regimen (cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2, vincristine 1.4 mg/m2 [maximum 2 mg] on day 1 and oral prednisone 100 mg on days 1-5). In Part 2 of the study patients were treated at the MTD of pralatrexate established in Part 1, with standard CHOP. In both parts of the study patients were treated with up to 6 cycles of therapy, or until toxicity or disease progression. Patients received antimicrobial prophylaxis, myeloid growth factor support, and “leucovorin rescue” throughout 6 cycles of therapy. Dose-limiting toxicities (DLT) were considered during the 1st cycle of Fol-CHOP and included: Grade 4 infections, treatment-related non-hematological toxicity ≥Grade 3, platelet count < 25 X 109/L at any time, or ANC < 0.5 X 109/L for >7 days despite G-CSF administration. Responses were assessed by the investigator per the Revised Response Criteria for Malignant Lymphoma (Cheson 2007).Results: A total of 31 patients have been enrolled (19 in Part 1; 12 in Part 2). MTD was not reached and pralatrexate dose of 30 mg/m2 in combination with CHOP was selected for Part 2 of the study as predefined by the protocol. The majority of patients were male, White, with the median age of 66 yrs (range, 18-78) at the time of enrolment. PTCL diagnoses included: anaplastic large cell lymphoma, anaplastic lymphomakinase-negative (ALCL, ALK-, n=5), peripheral T-cell lymphoma, not-otherwise specified (PTCL-NOS, n=18), and angioimmunoblastic T-cell lymphoma (AITL, n=5). Fol-CHOP was generally well tolerated with median RDI of 98%. Common (≥ 30%) adverse events (AEs) of any grade were fatigue (n=23), constipation (n=20), nausea (n=16), mucositis (n=14), diarrhea (n=12), anemia (n=9), vomiting (n=10) and oral pain (n=10). Most common (≥ 10%) AEs ≥ grade 3 were anemia (n=6), fatigue (n=4) and neutrophil count decreas (n=5). The only Grade >3 treatment-related AEs (≥10%) was neutrophil count decrease (n=4). SAEs were observed in 13 patients, treatment related SAEs were anemia, febrile neutropenia, dehydration, mucositis and nausea. Five patients withdrew from study: 2 due to disease progression, 1 due to AE and 2 due lapse >28 days between doses. In the 27 patients avaluable for response, the investigator assessed objective response (OR) and complete response (CR) rates were 89% wand 67%, respectively.Conclusions: The combination of pralatrexate and CHOP was well tolerated in treatment-naive PTCL patients. MTD of pralatrexate was not reached, and the protocol-defined maximum dose of 30 mg/m2 on days 1 and 8 of a 21-day CHOP cycle was recomended for future studies. The observed OR and CR rates warrant further evaluation of this regimen in newly diagnosed PTCL patients. DisclosuresShustov:Celgene: Other: Publication assistance; Spectrum Pharmaceuticals: Consultancy, Research Funding. Bhat:Spectrum Pharmaceuticals: Employment. Reddy:Spectrum Pharmaceuticals: Employment.

CHOP in Combination with Pralatrexate, a Novel Folate Analogue Metabolic Inhibitor in Patients with Previously Untreated Peripheral T-Cell Lymphoma (PTCL): Interim Results of the Phase 1 Trial

Background: Peripheral T-cell lymphomas (PTCL) are a heterogeneous group of mature T-cell and natural-killer-cell aggressive non-Hodgkin lymphomas associated with poor prognosis with current therapies. Numerous studies have reported poor survival for PTCL patients with a median Overall Survival (OS) shorter than 2 years and 5-year survival rates of <30%. Traditionally, patients with PTCL have been treated with a cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-like first-line chemotherapeutic regimen. Unfortunately, the prognosis remains poor with most patients relapsing within 2 years. Thus, improved front line treatment strategies are needed.Pralatrexate (Folotyn) is a folate analogue metabolic inhibitor that was the first drug approved in the US for the treatment of patients with relapsed or refractory PTCL (R/R PTCL). Approval was based on results from the pivotal Phase 2 PROPEL study (O'Connor et al, JCO, 2011) of pralatrexate in R/R PTCL, in which pralatrexate monotherapy demonstrated a durable clinical benefit (objective response rate of 29%). Pralatrexate is administered intravenously (IV) at a dose of 30 mg/m2 weekly for 6 weeks of a 7-week treatment cycle. Since pralatrexate and each of the components of the CHOP regimen target different aspects of tumor cell growth and proliferation, there is a potential for synergistic anti-tumor effect, and limited additive toxicities.Objectives: The primary endpoint of the study is the determination of the MTD of pralatrexate in combination with CHOP (Fol-CHOP) in previously untreated PTCL patients. Secondary endpoints included safety, tolerability and ORR (complete response [CR] + partial response [PR]) and pharmacokinetics.Methods: In this study, patients with PTCL received CHOP in combination with pralatrexate, repeated every 3-weeks for up to 6 cycles. Part 1 of the study was to determine the Maximum Tolerated Dose (MTD) of the Fol-CHOP combination. Once the MTD was determined, an additional 10 patients were treated in the Expansion Phase (Part 2). The cohort schema followed a traditional "3+3" design. Pralatrexate was to be administered as 10, 15, 20, 25, or 30 mg/m2 IV push over 3 to 5 minutes on Days 1 and 8 of each cycle. The starting cohort was CHOP + 10 mg/m2 of pralatrexate.Patients received prophylaxis with acyclovir and sulfamethoxazole/trimethoprim during the study and primary prophylaxis with growth factor (filgrastim or pegfilgrastim) support. Dose-limiting toxicities (DLT) were considered during the 1st cycle and included: Severe infections, study treatment-related non-hematological toxicity Grade 3-4, platelet count < 25 X 109/L at any time or ANC < 0.5 X 109/L lasting more than 7 days despite G-CSF administration.Results: A total of 12 patients have been enrolled in Part 1 of the study at the time of abstract submission. Nine patients have completed Cycle 1 and no DLT was reported. Among these nine patients, three patients each were treated at CHOP + 10 mg/m2, 15 mg/m2 and 20 mg/m2 of pralatrexate. One patient (11%) treated with CHOP + 10 mg/m2 had one serious adverse event (SAE) of febrile neutropenia that was deemed unrelated to any study drug. Only four Grade 3 AEs (anemia, constipation, mucosal inflammation, and nausea) were reported, in one patient (11%). The enrollment into the study continues.Conclusions: These interim results demonstrate that the combination of pralatrexate with CHOP (Fol-CHOP) is well tolerated, with all components of CHOP as well as pralatrexate being given at close to or at standard doses. The rates of AEs are comparable to those typically reported with CHOP alone. The study is ongoing to confirm the MTD and to assess preliminary efficacy of the Fol-CHOP combination. Updated results will be presented at the meeting. DisclosuresOki:Novartis: Research Funding. Barta:Celgene, Merck, Seattle Genetics: Research Funding; Janssen: Honoraria, Speakers Bureau. Sharma:Spectrum Pharmaceuticals: Employment. Song:Spectrum Pharmaceuticals: Employment. Mourya:Spectrum Pharmaceuticals: Employment.

Preclinical pharmacologic evaluation of pralatrexate and romidepsin confirms potent synergy of the combination in a murine model of human T-cell lymphoma.

T-cell lymphomas (TCL) are aggressive diseases, which carry a poor prognosis. The emergence of new drugs for TCL has created a need to survey these agents in a rapid and reproducible fashion, to prioritize combinations which should be prioritized for clinical study. Mouse models of TCL that can be used for screening novel agents and their combinations are lacking. Developments in noninvasive imaging modalities, such as surface bioluminescence (SBL) and three-dimensional ultrasound (3D-US), are challenging conventional approaches in xenograft modeling relying on caliper measurements. The recent approval of pralatrexate and romidepsin creates an obvious combination that could produce meaningful activity in TCL, which is yet to be studied in combination. High-throughput screening and multimodality imaging approach of SBL and 3D-US in a xenograft NOG mouse model of TCL were used to explore the in vitro and in vivo activity of pralatrexate and romidepsin in combination. Corresponding mass spectrometry-based pharmacokinetic and immunohistochemistry-based pharmacodynamic analyses of xenograft tumors were performed to better understand a mechanistic basis for the drug:drug interaction. In vitro, pralatrexate and romidepsin exhibited concentration-dependent synergism in combination against a panel of TCL cell lines. In a NOG murine model of TCL, the combination of pralatrexate and romidepsin exhibited enhanced efficacy compared with either drug alone across a spectrum of tumors using complementary imaging modalities, such as SBL and 3D-US. Collectively, these data strongly suggest that the combination of pralatrexate and romidepsin merits clinical study in patients with TCLs.

A Phase I/II Study of Bortezomib (VELCADE) in Combination with Pralatrexate in Relapsed/Refractory Multiple Myeloma

Abstract 4304 BackgroundMultiple myeloma (MM) is characterized by the accumulation of malignant plasma cells accompanied by end organ damage. Although cytotoxic chemotherapy including high dose chemotherapy with stem cell support have improved survival of symptomatic patients, all patients invariably relapse. For patients with relapsed disease further chemotherapy is generally of limited benefit, indicating the need for novel therapies.Pralatrexate is a folate antagonist which has been FDA approved for the treatment of peripheral T-cell lymphoma. It has been shown to be safe in combination with various cytotoxic agents. In preclinical studies, pralatrexate has been shown to be synergistic with the proteosome inhibitor bortezomib. This phase I/II study is being conducted with the support of the NCCN to determine the safety and maximum tolerated dose (MTD) of pralatrexate in combination with bortezomib in the treatment of relapsed/refractory MM. MethodsThe primary objectives were to determine the MTD and recommended phase II dose and toxicity profile of pralatrexate in combination with bortezomib. The secondary objectives were to determine clinical evidence of anti-myeloma activity based on response criteria of the International Myeloma Working Group Uniform Response Criteria (IMWGURC). Additionally, anti-tumor activity was measured by duration of response (DOR), progression free survival (PFS), and overall survival (OS). Eligible patients were age >18, with measurable MM that had relapsed following, or was refractory to at least 1 previous treatment. Refractoriness to bortezomib was allowed. Patients received pralatrexate intravenously on days 1, 8 & 15 in 3-dose cohorts of 10, 20 or 30 mg/m2 and bortezomib intravenously on days 1, 8 & 15 at a fixed dose of 1.3 mg/m2. Patients took folic acid 1mg daily as well as intramuscular vitamin B12 every 8–10 weeks. A standard 3+3 dose escalation was used for determining the MTD. In this study, dose-limiting toxicity (DLT) was determined during cycle 1 and defined as grade 3 febrile neutropenia, grade 3 or grade 4 non-hematologic treatment-related toxicity, or treatment delays exceeding 14 days in the first cycle of treatment. A maximum of 4 28-day cycles was planned. ResultsNine patients with a median age of 60 (55–74 years) have been enrolled on the study to date. The MTD has not been reached. Patients are currently enrolled in the 3rddose cohort. The median number of previous therapies was 2 (range 1–4). Eight pts (88%) had received previous treatment with bortezomib, and 8 with immunomodulatory agents. Two patients had undergone autologous transplant. Six patients had refractory disease, including 5 refractory to bortezomib. Seven patients had bony disease, including 5 (55%) with >3 lesions. FISH studies revealed 2 patients with monosomy 13 and one with a p53 deletion. Patients received a median of 2 treatment cycles (range 1–4). The median follow-up time is 12.4 months (range 0.46–22.9). To date, the most common grade 3 or 4 adverse events occurring in more than 10% of patients, were thrombocytopenia (66%) and neutropenia (22%). Grade 3 mucositis was observed in 1 patient and constituted a DLT. Subsequent patients were given leucovorin to take at the first sign of mucositis. One patient had a grade 3 shingles infection. Of the eight patients evaluable for response, 2 achieved a partial response, 5 had stable disease, and 1 progressed. The median duration of response was 46 days (range 38–54). After completion of the study 1 patient started maintenance, and 7 patients started alternative therapy including transplant in 3 patients. The median time to next treatment was 23 days (range 13–196). There were no deaths on the study. The median PFS was 7.6 months (range 0.4–18.8). The median OS was 12.4 months (range 0.4–22.9) ConclusionsThe combination of pralatrexate 30mg/m2 and bortezomib 1.3mg/m2 on days 1, 8, and 15 appears to be a safe treatment option for heavily pre-treated patients with multiple myeloma. The main toxicities of this regimen are thrombocytopenia and mucositis. Disclosures:Liedtke:Millennium: Research Funding.

Abstract 3567: Interaction of pralatrexate with the EGFR/MAPK pathway leads to synergistic activity with EGFR inhibitors

Abstract Background: Pralatrexate (FOLOTYN®), an antifolate targeting dihydrofolate reductase, has high affinity for reduced folate carrier-1 and is an efficient substrate for polyglutamation by folypolyglutamyl synthetase. Combinations of cytotoxics and small molecule EGFR inhibitors (EGFRi's) have had little clinical success. Recent demonstration that intracellular folates may modulate survival signaling pathways, including EGFR/MAPK, suggests a potential for rational combinations of antifolates and EGFRi's. This study investigated potential roles of the EGFR/MAPK pathway in pralatrexate sensitivity and explored combinations of pralatrexate with EGFRi's. Materials and Methods: Anti-proliferative effects of pralatrexate were evaluated in a panel of human cancer cell lines. mRNA expression was analyzed by qRT-PCR and protein was evaluated by Western blot. Effects of drug combinations were evaluated using the Chou &amp; Talalay method. Results: Pralatrexate displayed potent anti-proliferative effects in 9 of 15 human cancer cell lines, with HEP2 (head &amp; neck [H&amp;N]) and DU145 (prostate) cell lines showing IC50s of 50 nM and 15 nM, respectively. Sensitivity to pralatrexate correlated with higher pre-treatment mRNA expression of EGFR. After 5 hrs of exposure to 10 nM pralatrexate, increased phosphorylation of ERK1/2, MEK1/2, and the downstream target c-JUN was seen in HEP2 and DU145 cells. In addition, early activation of EGFR and EGFR protein degradation was observed. To further explore possible interactions between pralatrexate and the EGFR pathway, combination studies with EGFRi's were performed. Synergistic activity was observed in the MTT assay when pralatrexate was used in combination with erlotinib, gefitinib, and lapatinib in DU145, PC3, and LNCaP prostate and HEP2 H&amp;N cancer cells. Synergistic activity was most pronounced when pralatrexate was given prior to the EGFRi's. Conclusions: Higher expression of EGFR was associated with pralatrexate sensitivity in a panel of human cancer cell lines. Pralatrexate treatment resulted in activation of the EGFR/MAPK pathway. Sequential administration of pralatrexate followed by EGFRi's resulted in synergistic anti-tumor activity. These findings provide rationale for clinical evaluation of pralatrexate in combination with EGFRi's, in particular in tumors sensitive to antifolates and EGFRi's such as NSCLC and H&amp;N cancer. In addition, evaluation of pralatrexate in combination with inhibitors of downstream EGFR targets is warranted. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3567. doi:10.1158/1538-7445.AM2011-3567

Single agent and combination studies of pralatrexate and molecular correlates of sensitivity

Background:Pralatrexate is a dihydrofolate reductase (DHFR) inhibitor with high affinity for reduced folate carrier 1 (RFC-1) and folylpolyglutamate synthetase (FPGS), resulting in extensive internalization and accumulation in tumour cells. Pralatrexate is approved in the US for the treatment of relapsed or refractory peripheral T-cell lymphoma and is being investigated in various malignancies. Here, we evaluated molecular correlates of sensitivity to pralatrexate and explored combinations with a variety of anticancer agents.Methods:Antiproliferative effects of pralatrexate were evaluated in 15 human-cancer cell lines using the MTT assay. Gene expression was evaluated using qRT–PCR.Results:Pralatrexate and methotrexate had a similar pattern of cytotoxicity, pralatrexate being more potent. Pralatrexate potentiated the effects of platinum drugs, antimetabolites and EGFR inhibitors. Dose- and time-dependent cytotoxicity of pralatrexate correlated with high mRNA expression of FPGS. Acquired resistance to pralatrexate was associated with decreased RFC-1 expression, whereas methotrexate resistance correlated with increased DHFR expression, suggesting different mechanisms of acquired resistance.Conclusion:Pralatrexate was more potent than methotrexate in a panel of solid tumour lines. Our findings support the further clinical development of pralatrexate in combination with certain cytotoxics and targeted therapies, and suggest that RFC-1, FPGS and DHFR may be potential biomarkers of outcome.

A Phase 1/2A Open-Label Study of Pralatrexate and Gemcitabine in Patients with Relapsed or Refractory Lymphoproliferative Malignancies.

Background: Pralatrexate (PDX) is a novel targeted antifolate that is designed to accumulate preferentially in cancer cells. Pralatrexate has demonstrated activity in the treatment of non-Hodgkin's lymphoma (NHL). Single-agent gemcitabine (Gem) has demonstrated promising activity in relapsed Hodgkin's lymphoma, T-cell lymphoma, and select sub-types of B-cell NHL. Based on pre-clinical data demonstrating a schedule dependent synergy for this combination (pralatrexate + Gem) (Clin Cancer Res 2006; 12(3):924–932), a Phase 1/2a, non-randomized, open-label, multi-center trial was designed to assess the potential co-administration of these 2 agents. The primary objective of the study is to determine the maximum tolerated dose (MTD) and recommended Phase 2 dose when pralatrexate and Gem are administered with vitamin B12 and folic acid supplementation to patients (pts) with relapsed/refractory lymphoma.Methods: Initially, pts were assigned to a schedule of pralatrexate, followed the next day by Gem, once weekly for 3 of 4 weeks (Treatment group A). When this schedule was poorly tolerated, new cohorts were enrolled in a dose escalating fashion: Treatment group B – pralatrexate (10 mg/m2) followed the next day by Gem (300–400 mg/m2) once every 2 weeks (q 2 weeks); and Treatment group C – pralatrexate (10 mg/m2) followed 1 hour later by Gem (300–400 mg/m2) q 2 weeks. Eligibility criteria include histologically confirmed lymphoma, documented disease progression (PD) after 3 1 prior treatment, and ECOG PS £ 2.Results: As of August 2008, 20 pts have been treated on this study, including 11 males (55%) and 9 females (45%). Pt histology is as follows: 8 pts [40%] diffuse large B-cell lymphoma [DLBCL]; 1 pt [5%] follicular lymphoma, Hodgkin lymphoma (HL) (5 pts [26%]), T/NK-cell (5 pts [26%]), and composite DLBCL and PTCL (1 pt [5%]). Pts were heavily pre-treated having received a median of 4 prior regimens (range 3–12) with a median of 3 prior systemic regimens (range 2–10). Treatment group A was not well tolerated as evidenced by the incidence of Grade (Gr) 3–4 hematological toxicities. In comparison pts in treatment groups B and C had far fewer adverse events (AEs) with lower severity toxicities.Across all dose cohorts and treatment groups, the most frequently reported Gr 3–4 AEs considered to be treatment related have been neutropenia (9 pts [45%]) thrombocytopenia (9 pts [45%]), and anemia (8 pts [40%]). Preliminary efficacy data show 6 pts (30%) with partial response (PR): 4 with HL, 1 with DLBCL, and 1 with composite DLBCL and PTCL. PRs occurred on both the sequential dosing schedule (5 pts) and the same-day dosing schedule (1 pt). The HL pts with a PR were heavily pretreated (7, 8, 11, and 12 prior therapies) and all had received previous Gem, 3 of the 4 without response.Conclusion: The combination of pralatrexate and Gem can be safely administered on a q 2 week schedule. The MTD was established for the sequential day schedule as pralatrexate 10/Gem 300 (mg/m2). Dose escalation continues on the same day schedule. Pralatrexate and Gem administration at a frequency of 3/4 weeks is not feasible in heavily pretreated pts due to hematologic toxicity; however, when administered on a 2 q week schedule, the combination has shown a favorable safety profile. The combination of pralatrexate and Gem has shown encouraging activity in pts with heavily pre-treated, refractory lymphomas and enrollment in the study is ongoing to define the MTD on a same day schedule.CohortNumber of PtsDose Pralatrexate/Gem (mg/m2)Schedule#DLTsDLT (Grade)A1215/400Sequential days, 3/4 weeks2Thrombocytopenia (Gr 4); Neutropenia (Gr 3) & Thrombocytopenia (Gr 3)A-1210/400Sequential days, 3/4 weeks2Neutropenia (Gr 3) Thrombocytopenia Gr 3)A-2310/300Sequential days, 3/4 weeks2Thrombocytopenia (Gr 3) Neutropenia (Gr 3)B1310/300Sequential days, q 2 weeks0B2310/400Sequential days, q 2 weeks0B3215/400Sequential days, q 2 weeks2Cellulitis (Gr 3) Pulmonary embolus (Gr 3)C1310/300Same day, q 2 weeks0C2210/400Same day, q 2 weeks1Hypoxia (Gr 3) &

Phase I study of the antifolate pralatrexate given with vitamin B12 and folic acid supplementation in patients (pts) with advanced non-small cell lung cancer (NSCLC)

13006 Background: Pralatrexate is a novel antifolate that has shown promising activity in the treatment of pts with previously- treated NSCLC at doses of 135–150 mg/m2 IV every other week (q2w). [Krug, Clin Cancer Res 9(6), 2003; 6(9), 2000] The addition of vitamin B12 and folic acid supplementation may mitigate toxicity from pralatrexate and improve efficacy by allowing higher doses to be delivered. Methods: This study is designed to determine the maximum tolerated dose (MTD) of pralatrexate in combination with vitamin B12 and folic acid supplementation in pts with NSCLC. Key eligibility criteria include confirmed stage IIIB or IV NSCLC; at least 1 prior chemotherapy regimen; Karnofsky performance status (KPS) = 70%; and no other active concurrent malignancy. Using a rapid escalation design, pralatrexate was initially administered at a dose of 150 mg/m2 IV q2w, escalating by 40 mg/m2 increments in successive cohorts, with one patient per cohort if no dose limiting toxicity (DLT) is encountered. All pts receive vitamin B12 1 mg intramuscular q 8–10 weeks and folic acid 1 mg by mouth once a day beginning at least 7 days prior to pralatrexate. All patients undergo pharmacokinetic testing following their first and second dose of pralatrexate. Results: Between 1/05–12/06, a total of 9 pts have been treated at the following dose levels: 150 (n=1), 190 (n=1), 230 (n=1), and 270 (n=6). Patient characteristics include: 2 male/7 female; median age 63 (range 52–73); KPS 80–90%; all pts had stage 4 NSCLC; 5 pts received 1 prior regimen and 4 pts received 2 or more prior regimens. Grade 3 esophagitis was a DLT in one patient at the 270 mg/m2 dose. Three other patients experienced grade 1–2 mucositis at this dose level without limiting drug delivery. The trial is ongoing, and enrollment is planned at 310 mg/m2 q2w to determine the MTD. Conclusions: When given in combination with vitamin B12 and folic acid supplementation, pralatrexate has been well tolerated in this pt population, with an MTD at least twice as high as achieved in previous phase 1 testing without supplementation. We plan to conduct a phase 2 trial of pralatrexate with vitamin B12 and folic acid supplementation to see if a higher dose will improve efficacy. No significant financial relationships to disclose.

The Schedule-Dependent Effects of the Novel Antifolate Pralatrexate and Gemcitabine Are Superior to Methotrexate and Cytarabine in Models of Human Non-Hodgkin's Lymphoma

Methotrexate is known to synergize with cytarabine [1-beta-D-arabinofuranosylcytosine (ara-C)] in a schedule-dependent manner. The purpose of this article is to compare and contrast the activity of pralatrexate (10-propargyl-10-deazaminopterin)/gemcitabine to the standard combination of methotrexate/ara-C and to determine if schedule dependency of this combination is important in lymphoma. Cytotoxicity assays using the standard trypan blue exclusion assay were used to explore the in vitro activity of pralatrexate and gemcitabine against a panel of lymphoma cell lines. Both severe combined imunodeficient beige and irradiated nonobese diabetic/severe combined imunodeficient mouse xenograft models were used to compare and contrast the in vivo activity of these combinations as a function of schedule. In addition, apoptosis assays were conducted. Compared with methotrexate-containing combinations, pralatrexate plus gemcitabine combinations displayed improved therapeutic activity with some schedule dependency. The combination of pralatrexate and gemcitabine was superior to any methotrexate and ara-C combination in inducing apoptosis and in activating caspase-3. In vivo, the best therapeutic effects were obtained with the sequence of pralatrexate --> gemcitabine. Complete remissions were only appreciated in animals receiving pralatrexate followed by gemcitabine. These data show that the combination of pralatrexate followed by gemcitabine was superior to methotrexate/ara-C in vitro and in vivo, and was far more potent in inducing apoptosis in a large B-cell lymphoma. These data provide strong rationale for further study of this combination in lymphomas where methotrexate and ara-C are used.

A phase I clinical pharmacologic study of pralatrexate in combination with probenecid in adults with advanced solid tumors

The antifolate pralatrexate (10-propargyl-10-deazaaminopterin, PDX) demonstrates greater in vitro and in vivo antitumor efficacy than methotrexate. Preclinical models indicated that the efficacy of pralatrexate may be enhanced by coadministration with probenecid. The aim of this phase I study was to determine the maximum-tolerated dose of pralatrexate when combined with probenecid given every 2 weeks in humans. The starting dose was pralatrexate 40 mg/m(2) intravenously and probenecid 70 mg/m(2) intravenously administered every 14 days, where one cycle of treatment was every 28 days. The pralatrexate dose was initially fixed while probenecid dose escalation was explored. The pralatrexate area under the curve (AUC), terminal-half life (t1/2), and maximum plasma concentration (Cmax) were determined in cycle 1. Seventeen patients with advanced solid tumors were treated with a median of two prior chemotherapy regimens. Stomatitis was dose-limiting with pralatrexate 40 mg/m(2) and probenecid 233 mg/m(2). Mean pralatrexate AUC and half life (t1/2) increased with increasing doses of probenecid. No objective responses were seen. For patients with advanced solid tumors, the maximum-tolerated dose of this drug combination was pralatrexate 40 mg/m(2) and probenecid 140 mg/m(2). Vitamin B(12) and folate supplementation may allow for further dose escalation of pralatrexate and probenecid. This is a suitable question for a future study.