Updated results from a phase I clinical trial (protocol ID: NCI-01-C-0124; NCI-2792; NCT00012571) were reported. Patients with advanced solid tumors or lymphoma were treated with MS-275 orally initially on a once daily x 28 every 6 weeks (daily) and later on once every 14-days (every 14-day) schedules. The starting dose was 2 mg/m˛, and the dose was escalated in 3 to 6 patient cohorts based on toxicity assessments. With the daily schedule, the MTD was exceeded at the first dose level. Preliminary PK analysis suggested the half-life of MS-275 in humans was 39 to 80 hours, substantially longer than predicted by preclinical studies. With the every 14-day schedule, 28 patients were treated. The MTD was 10 mg/m˛, and DLT were nausea, vomiting, anorexia, and fatigue. Exposure to MS-275 was dose dependent, suggesting linear PK. Increased histone H3 acetylation in PBMC was apparent at all dose levels by immunofluorescence analysis. Up to 10 of 29 patients remained on treatment for > or = 3 months. The MS-275 oral formulation on the daily schedule was intolerable at a dose and schedule explored. The every 14-day schedule is reasonably well tolerated. Histone deacetylase inhibition was observed in PBMC. Based on PK data from the every 14-day schedule, a more frequent dosing schedule, weekly x 4, repeated every 6 weeks is presently being evaluated (Ryan QC, etal, J Clin Oncol, 10 Jun 2005;23(17):3912-22).

An open label, dose escalation, phase I clinical trial (protocol ID: CDR0000396776, JHOC-J0438, NCI-6798, JHOC-04060103, NCT00098891) of MS-275 in combination with isotretinoin in patients with metastatic, progressive, refractory, or inoperable solid tumors or lymphoma, was initiated in November 2004 at the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University (Baltimore, MD) and the Warren Grant Magnuson Clinical Center (Bethesda, MD), under Protocol Chair Roberto Pili, MD (tel: 410-502-7482), of Johns Hopkins. According to the protocol, patients are administrated oral MS-275 once on days 1, 8, and 15 and oral isotretinoin twice daily on days 1 to 21. Courses repeat every 28 days in the absence of unacceptable toxicity or disease progression. Cohorts of 3-6 patients receive escalating doses of MS-275 until MTD is determined. Up to 12 patients are then treated at the MTD. Patients are followed monthly. A total of 12 to 24 patients will be accrued for this trial. This trial was reported closed as of September 2006.

A phase I clinical trial (protocol ID: NCI-01-C-0124; NCI-2792; NCT00012571; NCT00354185) was initiated in March 2001 at the NCI in patients with solid tumors and NHL refractory to standard therapy, or for those for whom there is no known standard therapy, potentially curative, or capable of extending life expectancy. According to the protocol, participants were originally treated with MS-275 in 1 of 2 dosing schedules. In group 1, MS-275 is being administered in 6-week cycles of 1 dose a week for 4 weeks, with a 2-week break. This treatment option is open for accrual. Patients in group 2 were administered the drug once every other week; no further patients are being accepted into this part of the trial at the present time. Treatment in both groups may continue for more than 6 months, depending on benefits and side effects. Expected total enrollment is 75 patients. In updated results, MS-275 was administered PO to 3-6 fasting patients per dose level with refractory/relapsed solid tumors or lymphoma. The plasma PK profile of MS-275 was analyzed using a validated, quantitative method. Histone H3 and H4 acetylation was analyzed in peripheral blood mononuclear cells (PBMC) by immunohistochemical detection. Up to 17 patients have been enrolled on 3 schedules. In Schedule A, MS-175 (2-6 mg/m˛) is administered biweekly in patients with melanoma (n=3); colon cancer, prostate cancer, adrenocortical, carcinoid, rectal, Ewing’s sarcoma, and mesothelioma (n=1 each). In Schedule B, MS-175 (2 mg/m˛) is administered twice weekly for 3 weeks, with 1 week rest in patients with colon cancer (n=2), GIST (n=2), melanoma (n=1), and sarcoma (n=1). In Schedule C, MS-275 (4 mg/m˛) is administered weekly for 3 weeks with 1 week rest in patients with breast (n=2), prostate cancer, nsclc, colon cancer, renal cell carcinoma, melanoma, and leiomyosarcoma (n=1 each). A total of 80 cycles have been administered on Schedule A and 13 on Schedule B. No drug-related Grade 4 adverse events have been reported. The most common drug related adverse events were Grade 1-3 hypophosphatemia, asthenia, nausea, and anorexia. The MTD was not reached on Schedule A. Dose escalation of Schedule B was not pursued because of laboratory abnormalities, resulting in dose delays/omissions. The plasma profile of MS-275 demonstrates rapid absorption, with a Tmax of 0.5-2.0 hours, and a dose-dependent increase in systemic exposure over the dose range 2-6 mg/m˛. A biphasic elimination was noted, with an estimated T1/2 of 100 hours. Preliminary PD analyses indicate an increase in histone H3 and H4 acetylation in PBMC, compared with pretreatment. A patient with melanoma continued to exhibit a PR (Schedule A), and 1 patient each with Ewing’s sarcoma (Schedule A), rectal carcinoma (Schedule A) and melanoma (Schedule B) had SD after 60+, 38+, and 20+ weeks of therapy, respectively. PK analyses indicate that MS-275 is rapidly absorbed, with a T1/2 of 100 hours, and preliminary evidence of increased H3 and H4 histone acetylation has been observed. Potential antitumor activity has been noted in 4 patients, and enrollment on MS-275 4 mg/m˛ weekly for 3 weeks with 1 week rest is ongoing (Gore L, etal, ASCO04, Abs. 3026). This trial was closed in 2006.

A dose escalation, phase I clinical trial (protocol ID: JHOC-J0253; MSGCC-0050, NCI-2791, NCT00015925) was initiated at the University of Maryland Greenebaum Cancer Center with MS-275 in poor-risk hematologic malignancies, including accelerated phase or relapsing or chronic phase or blastic phase CML, untreated or recurrent or secondary adult AML, de novo or previously treated MDS, refractory anemia with excess blasts or excess blasts in transformation, recurrent or untreated adult ALL, chronic myelomonocytic leukemia (CMML), adult acute promyelocytic leukemia (M3), and refractory plasma-cell neoplasm. Trial objectives are to determine if this drug induces changes in hematologic differentiation, in terms of changes in morphology, cell surface marker expression, and acetylation status, and induces clinical response in these patients. According to the protocol, patients are treated with oral MS-275 daily on days 1 and 8. Courses repeat every 6 weeks in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients are treated with escalating doses of MS-275 until MTD is determined. Approximately 25-30 patients will be accrued for this trial. Judith Karp, MD, is the Protocol Chair. This trial was closed in July 2005.

A multicenter (n=3), dose-escalation phase I clinical trial (protocol ID: CDR0000405841; JHOC-J0443; NCI-6591; JHOC-04061109; NCT00101179) compared the efficacy of the combination of azacitidine (30, 40, or 50 mg/m˛) and MS-275 (2, 4, 6, 8 mg/m˛) to azacitidine (Vidaza; Pharmion) alone in treating patients (n=31) with myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia (CMMoL), or acute myeloid leukemia (AML). Study outcomes were the safety and toxicity of MS-275 and azacitidine in these patient populations, MTD and optimal phase II dose of MS-275 when combined with azacitidine, potential therapeutic activity of this regimen, and relationship between MS-275 PK, clinical response, and laboratory correlative endpoints. SC 5-azacitidine was self-administered daily for 10 days per the most successful dose schedule of a prior study with 5-azacitidine + sodium phenylbutyrate, while MS-275 was administered on days 3 and 10 of each 28-day treatment cycle. A total of 31 patients were treated (median age=63 years). Diagnosis types included MDS (n=13), CMMoL (n=4) and AML (n=14). AML subtypes include AML with trilineage dysplasia (AML-TLD) (n=7), relapsed AML (n=4), and primary-refractory AML (n=3). A total of 5 patients received < 4 cycles and were not considered evaluable for response (declining performance status, n=3; sepsis and death, n=1; recurrent DLT, n=1). At the MS=275 dose of 8 mg/m˛ and 5-azacitidine 40 and 50 mg/m˛/dose, 4 patients experienced DLT (laryngeal edema, n=2; delayed neutrophil recovery > 21 days, n=1; asthenia, n=1). No DLT occurred at any combination with lower MS-275 doses; however, Grade 2 fatigue was common at the MS-275 6 mg/m˛/dose and was considered excessive for chronic administration. Out of 27 evaluable patients, there were 2 CR, 4 PR, and 6 patients with bilineage improvement (2000 IWG criteria). Responses occurred at all dose combinations in patients with MDS (n=7), CMMoL (n=1), AML-TLD (n=3), and relapsed AML (n=1). Combining MDS and AML-TLD, responses developed in 10/20 patients. To date, median number of cycles administered to responding patients is 11. Median time to first objective hematologic response is 2 cycles, while median time to best hematologic response is 4 cycles. A total of 20 patients had clonal cytogenetic abnormalities, including 6 clinical responders. All 6 patients had a minimum decrease in abnormal metaphases of 50%, with 4 cytogenetic CR. Median time to best cytogenetic response was 4 cycles. Following 3 days of 5-azacitidine therapy alone, H3 or H4 acetylation (PBMC) was increased in 10/30 patients. Overall, H3 acetylation increased in 25/29 patients (median increase=2.5 fold). H4 acetylation increased in 28/29 patients (median increase=4-fold). The histone H2AX-gamma was induced in 7/29 patients after 3 days of 5-azacitidine (PBMC) and in 20/29 patients after MS-275 treatment. Median fold-increase in H2AX expression was 5.3. The combination of 5-azacitidine/MS-275 is clinically tolerable and leads to substantive cytogenetic remissions. The relative contribution of MS-275 is under examination in a current Intergroup study randomizing patients to the 5-azacitidine/MS-275 combination versus the comparable dose schedule of 5-azacitidine alone (Gore SD, etal, ASH06, Abs. 517).

A multicenter, dose escalation, phase I clinical trial (protocol ID: CDR0000405841, JHOC-J0443, NCI-6591, JHOC-04061109, NCT00101179) of MS-275 in combination with azacitidine in patients with MDS, CML, or AML was initiated in November 2004 under PI Steven Gore, MD (tel: 410-955-8781; steven.gore@jhu.edu), at Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University (Baltimore, MD). Other participating centers include the Warren Grant Magnuson Clinical Center and Mount Sinai School of Medicine. According to the protocol, patients are administered azacitidine SC on days 1 to 10, and oral MS-275 on days 3 and 10. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Cohorts of 3 to 6 patients are treated with escalating doses of MS-275 until MTD is determined. The dose of azacitidine is adjusted based on clinical response. Up to 9 additional patients are treated at the MTD. Patients who do not achieve hematologic improvement, PR or CR, but whose disease stabilizes after 4 courses of therapy, may be treated with an additional 4 courses of therapy at a higher dose than what was originally assigned. A total of 20-35 patients will be accrued for this trial. This trial was reported closed as of August 2007.

A randomized, open label, phase II clinical trial (protocol ID: 309100; EudraCT No. 2004-002395-41; NCT00185302), sponsored by Bayer Schering Pharma, began in December 2004 to compare 2 dosage schedules of MS-275 for safety and efficacy in patients with metastatic melanoma. Primary outcome was tumor response rate. Secondary outcomes were TTP and survival at 6 months. This trial was completed in November 2006.

A multicenter, nonrandomized, open label, phase I/II trial (protocol ID: CDR0000504083, JHOC-J0658, NCI-7759, JHOC-NA_00003114; NCT00387465) was initiated in August 2006 with azacitidine, administered in combination with MS-275, in patients with refractory, metastatic or inoperable non-small cell lung cancer (nsclc), previously treated with one chemotherapeutic regimen. The phase I dose-escalation trial of azacitidine in this combination is followed by an open label, phase II trial. The trial’s primary objectives are to determine MTD of the combination (phase I) and the ORR (phase II). Secondary outcome measures include safety, tolerability, toxicity, PK, PFS, and overall survival at 1 year. Also pharmacodynamic effects are to be assessed based on DNA methylation, histone acetylation, and gene re-expression by blood and sputum analysis (and tissue biopsies from select patients). According to the protocol, in phase I, patients are treated with azacitidine SC on days 1 to 6 and 8 to 10 and oral MS-275 on days 3 and 10. Treatment repeats every 28 days in the absence of disease progression or unacceptable toxicity. Cohorts of 3 to 6 patients are treated with escalating doses of azacitidine until MTD is determined. In phase II, patients are treated with azacitidine as in phase I at the MTD and MS-275 as in phase I. Patients undergo plasma sample collection for PK evaluation before beginning treatment and then at days 1, 10, and 17. Patients also undergo blood and sputum collection to evaluate the pharmacodynamic effects of azacitidine and MS-275 on DNA methylation before beginning treatment and then at days 10 and 29. After completion of study treatment, patients are followed periodically for 4 weeks. A total of 44 patients will be accrued in this trial. Participating institutions include the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, under Study Chair Charles M. Rudin, MD, PhD, and University of New Mexico Cancer Center (Albuquerque, NM).