- Confused by something in my notes- get further background details on MYRX research webpage
- During 1q2011 eliminated 40% of employees...terminated drug discovery and related activites. This was not a sudden conclusion. Will focus financial and physical assets on the 4 internally-generated lead programs
- Have attracted partnering interest from worldwide leading pharmaceutical and biotech companies
- p2b trial of azixa in first line glioblastoma multiforme (GBM) initiated 12/2010. after surgery patients will receive radiation and then temozolomide +/- azixa. PFS is the primary endpt. OS is a secondary endpoint...This trial will help design pivotal p3 program and provide supporting data for NDA. Will enroll 120 pts in US and India
- 11/2010 presented data showing durable 3rd line responses in GBM pts at SNO meeting
- ASCO 6/2011 2nd line azixa monotherapy data will be released
- will use RANO progression criteria in new study based on analysis of previous data.
- expect biomarker data and additional nonclinical studies could allow companion diagnostic to ID potential responders
- MPC-3100. structure first revealed at AACR 2011. unique from 2 other classes of HSP90 inhibitors.
- MPC-3100 is in final stages of p1 trial in late stage cancer pts. Continous daily dosing. Good oral absorption/PK. Well tolerated with low side effect, 12 hr half life in human pts...now in 7th cohort. no drug related grade 3-4 SAE
- MPC-3100 nonclinical studies ongoing to ID drug combinations and inidcations for p2 studies
- IND enabling studies underway for alanine produg MPC-0767, more soluble. Parent molecule MPC-3100 is the only detectable metabolite in pasma. Think need only bioequivalnce p1 study in healthy volunteers with the prodrug before substituting for MPC-3100. But have yet to discuss this with FDA.
- MPC-9528 orally bioavailable cancer metabolism inhibitor. AACR data showed synergy w/ DNA damaging agents. Exploring companion diagnostic for this as well. Up tp 40% of pts may be good candidate due to single enzyme deficiency in their tumors
- IKK-epsilon pgm-originally studied because this is a breast cancer oncogene. Also a critical enzyme in the TLR cascade involved in several autoimmune diseases. Prevents downstream activation of IFN-a/b. Lead compound has picomolar activity, excellent selectivity, and orally bioavialbility. Data wil be presented in London at EULAR meeting later in May. Plan to partner and expand scope to develop leads for other indications
- At 3/31/11 $123.7m cash and equivalents. used $9.4m cash 1q2011 to fund operations. 25.65m shares outstanding. net loss $12.8m 1q2011
- expect r&d costs to increase as enroll p2b azixa trial
- cash thru 6/30/13 for planned operation's w/o any new transactions
- q&a session:
- In the industry, there has been much focus lately on targeted cancer therapies, but big pharma know these only address small parts of the markets. The seek some more generalized mechanisms with broader applicabilities. Ask themselves, can you really get away w/ $120k/yr cost for small group of pts?
- Azixa- want to read out p2b trial, then evaluate whether to partner or go alone
- MPC-3100 HSP90 inhibitor- good target tarnished by bad compounds. Have detected uptick in partnering interest.-- previously companies had shown interest but pull away due to problems with other moelcules. Can wait before entering into discussions for this, if at all.
- MPC-9528 Cancer metabolism inhibitor- at least one big pharma is hiring head of Cancer Metabolism. Now trying to establish what is best way to develop CM inhibitors. Very close to opening IND...may be better off keeping compound thru IND and maybe p1 before partnering.
- Oral anti-interferon (IKKe inhibitor)- outside scope of company. Regard this as a program, not just a single compound. Initial preclinical RA study prompted by potential partners...even though their first interest is in lupus, takes 1 yr to generate preclinical lupus model data. Collagen induced RA has been shown to be predictive for human activity. In partnering discussions for the program, series of IND candidates starting with lupus, then IBD, psoriasis. dont wish to take into IND alone because outside focus.
- Azixa part "a" of p2b study (never done in combo w/ radiation)- dose reduction of azixa for a group of pts to make sure there is not any additive toxicity. If not, escalate to normal dose and start randomizing. Have to allow 2 cycles (8 wks) from 3-6 pts per dose...Start with small number of centers to do the first stage. Large number will be ready to enroll part "b". Have enrolled pts (wont say # so far), no drug interactions seen so far.
- Goal to switch to MPC-0767 will not slow down start of p2 program, in fact may accelerate HSP90 program.
- MPC-0767 would allow lower COGS and lower tablet burden
- The HSP90 compounds ahead of them in the field are all IV infusions. This is okay in pts like NSCLC amenable to weekly visit to doctor for IV. Oral bioavailability is more appealing to pts for many types of cancer. Not trying to compete directly in same cancers as leading next generation compounds (aka ganetespib STA-9090 from SNTA). Don't diagree that NSCLC makes sense, but won't go there in competition with these molecules. Combo w/ other oral cancer meds for certain indications.
0 Comments
May 26, 2011 London, UK #THU0254
MPI-0485520, A SMALL MOLECULE INHIBITOR OF IKKE/TBK1 IS ACTIVE IN A MOUSE COLLAGEN-INDUCED ARTHRITIS MODEL B. Richards 1, V. Baichwal 1, M. Cronin 1, L. Reeves 1, D. Papac 1, A. Yungai 1, P. Sebahar 1, R. Holcomb 1, D. Wettstein 1, P. Bartel 1,*, R. Carlson 1 1MYREXIS, Salt Lake City, United States Background: Activation of the innate immune system has been proposed as a potential trigger for chronic inflammation associated with rheumatoid arthritis (RA). The innate immune system is activated within fibroblast-like synoviocytes via Toll-like receptors (TLRs) leading to secretion of proinflammatory chemokines that promote recruitment of inflammatory cells to the joint. The IKK-related kinases IKKε and TBK1 are essential in propagating TLR activation to IRF3 and IRF7 transcription factors. Phosphorylation of IRF3/7 leads to increased production of proinflammatory factors (IFN-β, RANTES, IP-10, MIP-1α, and IL-6) and proteinases (MMP-3 and MMP-9) and several of these proteins have been previously shown to be overexpressed in synoviocytes from RA patients. Objectives: To determine if the potent and selective IKKε/TBK1 inhibitor MPI-0485520 reduces collagen-induced arthritis (CIA) in mice. Methods: MPI-0485520 in vitro activity was assayed using recombinant IKKε and TBK1 enzymes. Production of the TLR3-induced cytokines, RANTES, IFN-β, IP-10, and MIP-1α, by fibroblast-like synoviocyte cells was measured by ELISA. In vivo efficacy of MPI-0485520 was determined in a mouse model of collagen-induced arthritis. Clinical arthritis score, weight, anti-collagen IgG titers and joint histology were evaluated in diseased mice. Results: MPI-0485520 potently inhibits IKKε and TBK1 activities in vitro with IC50 values < 1 nM and reduces TLR3-induced RANTES, IFN-β, IP-10, and MIP-1α production in cultured fibroblast-like synoviocytes with IC50 values of 61, 12, 48 and 35 nM, respectively. MPI-0485520 also demonstrated efficacy in a collagen-induced arthritis model. Mice dosed for 16 days with either 100 or 150 mg/kg MPI-0485520 showed significant, dose-dependent reduction (p < 0.05) of 29% and 45%, respectively, in cumulative clinical arthritis score (number of joints affected, degree of erythema, and amount of swelling). The 100 and 150 mg/kg doses were well tolerated and resulted in 23% and 42% lower weight loss (p < 0.05), respectively, than vehicle-treated, collagen-immunized mice. Measurement of paw and joint histology showed a significant reduction (p < 0.05) of 37% in inflammation, pannus formation, cartilage loss, and bone destruction at the 150 mg/kg dose. The titer of arthritis-inducing anti-collagen antibodies was not modulated by MPI-0485520. Conclusions: To our knowledge, this is the first example of an IKKε/TBK1 small molecule inhibitor demonstrating activity in a mouse model of arthritis. These results are consistent with IKKε-knockout mouse studies which demonstrated a role for IKKε in the progression of induced arthritis. Based on these observations, we anticipate that an orally available drug targeting the IKKε/TBK1 kinases may benefit patients suffering from rheumatoid arthritis. Myrexis will present the following poster on Azixa:
Saturday June 4th: Poster Presentation Abstract #2088 "Phase II study of verubulin (MPC-6827) for the treatment of subjects with recurrent glioblastoma naïve to treatment with bevacizumab." Lyndon J. Kim, MD Myrexis $MYRX Presentations on MPC9528 Cancer Metabolism inhibitor at AACR meeting April 2-6, 20113/21/2011 Abstract #577 "Basal NAD levels and Nampt expression correlate with in vitro and in vivo sensitivity of tumor cell lines to the Nampt inhibitor MPC-9528"
J. Jay Boniface, Vijay R. Baichwal, Daniel M. Cimbora, Lynn DeMie, Tracey C. Fleischer, Andrew D. Gassman, Siavash Ghaffari, Jeremy P. Green, Jeff S. Flick, Ryan T. Terry-Lorenzo, Damon I. Papac, Ashley Peterson, Rosann Robinson, Robert O. Carlson. Myrexis, Inc., Salt Lake City, UT Background: MPC-9528 is a potent and selective inhibitor of the NAD biosynthetic enzyme nicotinamide phosphoribosyltransferase (Nampt). Inhibition of Nampt by MPC-9528 causes depletion of cellular NAD followed by a decrease in ATP and cell death. Cancer cells develop dependence on Nampt due to increased metabolic demands and the elevated activity of enzymes such as poly(ADP-ribose) polymerases (Parps) that consume NAD. MPC-9528 has shown anti-tumor activity, ranging from no response to complete regression in a variety of xenograft models. Materials and Methods: In vitro Nampt activity and cellular NAD levels were measured in coupled biochemical reactions. Cellular Parp activity was measured by immunofluorescent detection of poly(ADP-ribose) (PAR). Enzyme protein and mRNA levels were quantified by western blot and qRT-PCR, respectively. Mechanism of cell death was determined by Caspase 3/7 activity, Caspase 3 and Parp1 cleavage, and SytoxGreen staining. Cell viability was based on ATP levels. Xenografts were performed in nu/nu mice. Results: MPC-9528 inhibited Nampt activity in vitro with an average IC50 of 40 pM and suppressed cellular NAD levels and nuclear PAR levels, with potencies of 170 pM and 120 pM, respectively. In a screen of 93 cancer cell lines of diverse origin, MPC-9528 had a median TC50 of 2.8 nM with a range of 100 pM to 62 nM. Similar to cultured cells, a range of tumor responses was observed in six different xenograft models. In HCT116 colon carcinoma and HT1080 fibrosarcoma xenografts, oral administration of MPC-9528 at 75 mg/kg intermittently resulted in tumor regressions. In contrast, similar treatment of MIA PaCa-2 pancreatic cancer, N87 gastric carcinoma or HCC827 and NCI-H460 lung cancer xenografts led to partial tumor growth inhibition or no response. The effects in xenografts correlated with TC50 values for MPC-9528 for these cell lines in culture, which ranged from 260 pM to 24 nM. The TC50 values also correlated well with basal cellular NAD levels, IC50 values for MPC-9528-induced NAD depletion, and Nampt protein expression, but not with expression of three other enzymes involved in NAD metabolism - Naprt, Qprt or Parp1. The mechanism of cell death induced by MPC-9528 was cell type dependent and did not correlate with MPC-9528 potency in culture. Conclusions: NAD levels in cancer cell lines are primarily dependent upon the Nampt pathway. The differential sensitivity of tumor cells to the Nampt inhibitor MPC-9528 is likely due to the magnitude of NAD production, which is a function of Nampt expression. MPC-9528 has the greatest effect on tumor cell lines with lower Nampt expression; therefore, a companion diagnostic based upon Nampt expression in primary tumor specimens could be used to select patients most likely to respond to MPC-9528 monotherapy in the clinic. Abstract #2551"The Nampt inhibitor MPC-9528 synergizes with DNA damaging agents" Ryan T. Terry-Lorenzo, Thomas B. Douce, Harry A. Austin, J. Jay Boniface, Daniel M. Cimbora, Tracey C. Fleischer, Robert O. Carlson. Myrexis, Inc., Salt Lake City, UT Background: MPC-9528 reduces cellular NAD levels and causes cell death, by blocking the NAD salvage pathway through inhibition of nicotinamide phosphoribosyltransferase (Nampt). Many DNA damaging agents also reduce cellular NAD levels, by activating the NAD consuming enzyme poly(ADP-ribose) polymerase (Parp). We hypothesized that the combination of a Nampt inhibitor and a DNA damaging agent would synergize in killing cancer cells, due to a combined effect on NAD levels through two independent mechanisms. Methods: Cellular NAD was measured using a coupled enzymatic assay. Drug combination experiments were performed in HCT116 colon carcinoma cells, using measurement of ATP levels as a cell viability endpoint. Synergy, antagonism, or additivity was assessed using the MacSynergy II program. Results: In HCT116 cells, saturating doses of MPC-9528 induced depletion of NAD with a half-life of 5 hours and a decrease in ATP that was delayed approximately 14 hours relative to NAD. Lower, sublethal concentrations of MPC-9528 induced partial NAD depletion without a concomitant ATP loss. At these sublethal concentrations, MPC-9528 was found to synergize with the DNA alkylating agents temozolomide and streptozotocin, which are known to activate Parp. Additionally, MPC-9528 was found to synergize with two structurally different thymidylate synthase inhibitors, 5-fluorouracil (5-FU) and raltitrexed, neither of which have been reported to activate Parp. Individually, 5-FU and raltitrexed each caused NAD depletion in HCT116 cells, which was enhanced by combination with MPC-9528. Furthermore, both 5-FU- and raltitrexed-mediated NAD depletion and synergy with MPC-9528 were completely blocked by the Parp inhibitor olaparib. Conclusions: Parp activation induced by the alkylating agents temozolomide and streptozotocin, or by the thymidylate synthase inhibitors 5-FU and raltitrexed, is the basis for tumoricidal synergy with the Nampt inhibitor MPC-9528. This synergy is a direct consequence of the NAD depletion resulting from Parp activation coupled with the inhibition of NAD synthesis due to Nampt inhibition. These results provide a basis for clinical combination of MPC-9528 with the agents studied here or with related agents that induce Parp activation. Abstract #3526 "Coadministration of nicotinic acid with the Nampt inhibitor MPC-9528 enhances antitumor activity in Naprt deficient cancer cells in culture and in xenografts" Tracey C. Fleischer, Vijay R. Baichwal, J. Jay Boniface, Daniel M. Cimbora, Lynn DeMie, Thomas B. Douce, Andrew D. Gassman, Damon I. Papac, Ashley Peterson, Rosann Robinson, Ryan T. Terry-Lorenzo, Robert O. Carlson. Myrexis, Inc., Salt Lake City, UT Background: The tumoricidal small molecule MPC-9528 is a picomolar inhibitor of nicotinamide phosphoribosyltransferase (Nampt). Nampt catalyzes the first and rate-limiting step in NAD synthesis from nicotinamide. Nicotinic acid phosphoribosyltransferase (Naprt) catalyzes the first and rate-limiting step in an alternate pathway of NAD synthesis from nicotinic acid (NA). Cancer cells are particularly dependent on NAD and many cancer cell lines, but not most normal tissues, are deficient in Naprt activity. Therefore administration of NA could prevent MPC-9528-induced NAD depletion in normal tissues, but not in Naprt-deficient tumors, resulting in greater therapeutic index and efficacy. Methods: Cell viability was determined based on ATP levels. Naprt protein expresson was quantified by western blot and qRT-PCR. NAD was acid-extracted from cells and quantified by a coupled reaction based on fluorescent resorufin. Xenograft studies were performed in nu/nu mice. Results: In 44 out of 153 cancer cell lines surveyed, NA did not prevent MPC-9528-induced cell death, which correlated with low to undetectable levels of Naprt. MPC-9528-induced NAD depletion and cell death in HCT116 colon carcinoma cells were prevented by the addition of NA, consistent with high Naprt expression. A single dose of MPC-9528 at the maximum-tolerated dose (MTD) of 75 mg/kg caused tumor regression in HCT116 xenografts and NA coadministration completely blocked this effect. NA also completely blocked mortality in mice induced by 300 mg/kg MPC-9528, consistent with the finding that most mouse tissues have high Naprt expression. In Naprt-deficient MIA PaCa-2 xenografts, NA coadministration allowed tolerance of 200 mg/kg MPC-9528 with a substantially increased anti-tumor response relative to the MTD of 75 mg/kg MPC-9528 alone. Conclusions: Low Naprt expression correlates with the lack of effect of NA on MPC-9528 tumoricidal activity. Because Naprt deficiency is prevalent in cancer cell lines and in primary tumor specimens, but not in normal tissues, NA coadministration with MPC-9528 should increase the tolerability and efficacy of MPC-9528 in patients with Naprt-deficient tumors. A companion diagnostic designed to measure Naprt expression or activity in tumors could be used to identify tumors that would most likely benefit from such combination therapy. Abstract #4386 "Administration of nicotinic acid reduces or prevents adverse effects of MPC-9528, a potent and selective Nampt inhibitor" Gary G. Mather, Valerie L. Belcher, Anna Costa, Lynn DeMie, Orvelin Roman, Lori Fotheringham, Chad Bradford. Myrexis, Inc., Salt Lake City, UT Background: Inhibition of Nampt in cancer cell lines decreases NAD levels and induces cell death. We evaluate the potential toxicity of MPC-9528, a Nampt inhibitor, and investigate the effects of coadministration of nicotinic acid (NA), the substrate for an alternate pathway leading to NAD formation in normal tissues but lacking in many cancer cells. Methods: SD rats 8/sex/group were administered MPC-9528 at doses of 0, 10, or 15 mg/kg/day, or 15 mg/kg/day + 200 mg/kg/day of NA. Three additional rats were used to evaluate recovery after 7 days without treatment. Pathology was assessed at scheduled necropsies and PK parameters were determined, organ weights recorded, and selected tissues examined microscopically. Subsequently, CD-1 mice were given single oral doses of MPC-9528 at levels known to be efficacious in xenografts or lethal (75 or 300 mg/kg, respectively). NAD levels and white cell counts were determined. Female rats (n=6) were administered MPC-9528 (15 mg/kg/day) with or without pretreatment with NA (200 mg/kg/day) for 9 days. NAD levels were quantified by LC/MS/MS. Results: Cmax and AUC in females were approximately five times those in male rats. Two females died in the 10 mg/kg group and 8/11 females in the 15 mg/kg group. There were no deaths in male rats or in females dosed with MPC-9528 and NA. Leukocyte counts were reduced (36.4-77.0%) for all groups compared to controls. The reduction for rats treated concurrently with NA was less than groups treated with MPC-9528 alone. Leukocyte counts partially recovered 7 days off drug. There were no significant changes in clinical chemistry at any dose in male rats. AST and CPK were increased in a single female compared to controls. Albumin and total protein were reduced in females treated at 10 or 15 mg/kg/day. Thymus weights were reduced in all treated groups and spleen weights were reduced in females. These changes were not observed at the recovery sacrifice. Testis weight was reduced at both terminal and recovery in MPC-9528 treated males. Lymphoid depletion was noted on histopath. Clinical pathology, organ weight, and histopath changes were either reduced in severity or prevented by concurrent NA. NAD levels in mice given a single dose of 75 mg/kg were reduced >95% and white counts were reduced from a mean of 2.2 x 106/mL to 0.2 x 106/mL by Day 6. Lethality of a 300 mg/kg single dose in mice was completely prevented by coadministration of 1000 mg/kg NA. Similarly, NAD levels in rat blood decreased >50% by Day 6 in females administered MPC-9528 (15 mg/kg/day), however, with concurrent NA, NAD levels were reduced less than 30%. Conclusion: Coadministration of NA prevented or reduced the severity of adverse effects associated with daily administration of higher doses of MPC-9528. These data suggest that coadministration of NA has the potential to increase the therapeutic margin and to abrogate adverse clinical events in future clinical studies of MPC-9528. Abstract #LB-393 "The cancer metabolism inhibitor MPC-9528 induces tumor regression in xenograft models with multiple dosing schedules by causing rapid and sustained reduction in tumor NAD" Vijay R. Baichwal, Adam J. Willardsen, Jeff W. Lockman, Brett J. Murphy, Ruth Gordillo, Tracey C. Fleischer, Chad L. Bradford, Damon I. Papac, Gary G. Mather, Robert O. Carlson. Myrexis, Inc., Salt Lake City, UT --this is a late-breaking abstract and the full text abstract results are not yet available online Myrexis MYRX abstracts on MPC3100 HSP90 inhibitor to be presented at AACR meeting April2-6th3/21/2011 Abstract #2617 "MPC-3100, a synthetic Hsp90 inhibitor, induces biomarker changes in vitro and in vivo"
Vijay R. Baichwal, Brita Brown, Rosann Robinson, Daniel Cimbora, Daniel Wettstein, Andrew P. Beelen, Gary G. Mather, Robert O. Carlson. Myrexis Inc., Salt Lake City, UT Introduction: MPC-3100 is a fully synthetic, orally bioavailable, Hsp90 inhibitor in clinical development. It is broadly active in xenograft models with anti-tumor activity ranging from tumor regression to tumor growth inhibition in many cancer types including colon, gastric, ovarian, prostate, breast, lung and myeloid leukemia. Here we evaluate the effect of MPC-3100 on stability of client proteins in cells and xenograft tumors. We also determine the effect on Hsp70 protein levels, a biomarker of Hsp90 inhibition, in peripheral blood mononuclear cells (PBMCs) from cancer patients receiving MPC-3100. Methods: Her2, Akt, Cdk4, c-Raf and Hsp70 client protein levels were monitored in cell culture with protein immunoblots. Formalin-fixed, paraffin-embedded sections of xenograft tumors from mice dosed orally with MPC-3100 were analyzed by immunohistochemistry (IHC) to monitor changes in Her2, Akt and Hsp70 protein levels. To monitor changes in Hsp70 in cancer patients treated with MPC-3100, PBMCs were collected prior to drug administration, 8 and 24 hours post-dose on Day 1 and 24 hours post-dose on Days 7 and 21 of the first treatment cycle. Hsp70 protein levels were determined by ELISA. Results: Exposure of HCT-116, NCI-N87 and DU-145 cells to MPC-3100 in vitro resulted in a time-dependent reduction in client protein levels with maximal reduction by 24 hours. The IC50 values for client protein reduction ranged from 0.1 μM to 0.5 μM, comparable to the cellular cytotoxicity values of MPC-3100 at 72 hours for the various cell lines. IHC revealed reduction in Her2 and Akt protein in N87 xenografts in mice given a single oral dose of 200 mg/kg MPC-3100 relative to tumors from animals dosed with vehicle. Healthy volunteer PBMCs exposed to 1 μM MPC-3100 for 24 hours ex vivo revealed a reduction in Akt, c-Raf and Cdk4 protein levels ranging from 50% to 90%. PBMCs from cancer patients receiving MPC-3100 showed an increase of 28 to 589 ng of Hsp70 protein per mg total protein over baseline by Day 8. The increase in Hsp70 expression was seen as early as 8 hours after the first dose and sustained through at least Day 22. Conclusions: The changes in client proteins and biomarkers observed in cells and tumor xenografts exposed to MPC-3100 confirm that the cellular cytotoxic activity and anti-tumor activity in xenografts are a result of Hsp90 inhibition. The consistent increase in Hsp70 expression in PBMCs from cancer patients receiving MPC-3100 indicates that Hsp90 function is inhibited in patients at doses that have been well tolerated in the clinic. Abstract #2628 "Antitumor activity of MPC-3100, a synthetic Hsp90 inhibitor, in combination with erlotinib and sorafenib" Vijay R. Baichwal, Brita Brown, Daniel Wettstein, Damon I. Papac, Gary G. Mather, Robert O. Carlson. Myrexis Inc., Salt Lake City, UT Introduction: MPC-3100 is a fully synthetic, orally bioavailable, Hsp90 inhibitor in clinical development. It is active as a single agent in xenograft models with many cancer types including colon, gastric, ovary, prostate, breast, lung and myeloid leukemia. We evaluate here the activity of MPC-3100 in combination with erlotinib or sorafenib in xenograft models. Methods: Three to five million cells, depending on cell-type, were implanted subcutaneously into athymic mice (nu/nu) for tumor studies. Dosing was initiated when median tumor volume was >100 mm3. All compounds were dosed orally, once daily. MPC-3100 (100 mg/kg) and erlotinib (100 mg/kg) were dosed on Days 1-21 and sorafenib (60 mg/kg) was dosed on Days 1-9. Results: Anti-tumor activity for the combination of MPC-3100 and erlotinib was compared to that of the single agents in a lung cancer (A549) xenograft model sensitive to EGFR inhibition. Administration of MPC-3100 or erlotinib resulted in 52% and 64% tumor growth inhibition (TGI), respectively relative to vehicle by the end of dosing on Day 19. By contrast, the combination of MPC-3100 and erlotinib resulted in 30% tumor regression over the same period. Thus the combination of MPC-3100 and erlotinib was more effective at inhibiting tumor growth than either agent alone (p<0.05). The combined anti-tumor activity of MPC-3100 and sorafenib was compared to administration of the single agents in a xenograft model with the melanoma cell line A375 that harbors the activating B-raf mutation, V600E. The median tumor volume (MTV) of the cohorts dosed with vehicle, MPC-3100 or sorafenib as single agents was comparable and increased by 4.8-, 6.4- and 8.2-fold, respectively by the end of dosing on study Day 20, whereas MTV of the cohort dosed with a combination of MPC-3100 and sorafenib increased by only 1.6-fold. The combination of MPC-3100 and sorafenib resulted in 66% tumor growth inhibition relative to vehicle on Day 20 and was more effective at inhibiting tumor growth than single agent (p<0.05). Conclusions: The combination of MPC-3100 with erlotinib or sorafenib shows greater anti-tumor activity than either agent alone. Thus, in addition to its broad activity in xenograft models as a single agent, MPC-3100 has the potential to be combined with other targeted therapies. Abstract #3233 "Comparative in vitro and in vivo metabolism of MPC-3100, an oral HSP90 inhibitor, in rat, dog, monkey and human"Damon I. Papac1, J. Scott Patton1, Leslie Reeves1, Katrina Bulka2, Lynn DeMie1, Orvelin Roman, Jr.1, Chad Bradford1, Se-Ho Kim1, Rajendra Tangallapally1, Richard Trovato1, Benjamin Markovitz3, Ashok Bajji1, Daniel Wettstein1, Vijay Baichwal1, Gary Mather1. 1Myrexis, Salt Lake City, UT; 2Myriad Genetics, Salt Lake City, UT;3Nease Corporation, Cincinnati, OH Introduction: MPC-3100, an 8, 9-disubstituted purine, is an orally bioavailable HSP90 inhibitor currently in Phase 1 clinical development. The objectives of these studies were to compare the metabolism of MPC-3100 in preclinical species to select the species most appropriate for toxicological testing and to identify the major phase I and II metabolites formed both in vitro and in vivo in rats, dogs, monkeys and humans. Methods: MPC-3100 was incubated with liver microsomes from rats, dogs, monkeys, and humans. In addition, urine, feces, and bile were collected from rats dosed with MPC-3100 intravenously (5 mg/kg) or orally (50 mg/kg), and urine was collected from dogs (2 mg/kg) and cynomolgus monkeys (2.5 mg/kg) dosed intravenously. Metabolites were identified by liquid chromatography electrospray-ionization mass spectrometry. Quantitative analysis was performed with an AB Sciex 4000 Q-trap and qualitative analysis was conducted on a high resolution Agilent Q-TOF 6520 mass spectrometer. Six authentic standards were synthesized and used to confirm structural identity. Results: In human liver microsomes, four distinct peaks were observed following chromatographic analysis. Three of these were conclusively identified using synthetic standards, accurate mass, and chromatographic retention time. The most abundant metabolite in all species was the catechol. In human, monkey, and dog liver microsomes, the next most abundant metabolite was formed by oxidation of the 2-hydroxypropan-1-one moiety to propane-1, 2-dione. A third metabolite present in all incubations was the de-amidated product of MPC-3100. It was formed in microsomes in the absence of NADPH suggesting that its formation was due to pH-mediated hydrolysis. A fourth metabolite formed by the addition of oxygen (+16 Da) within the methylenedioxyphenyl ring was assigned based solely upon its product ion spectrum. Following intravenous administration of MPC-3100 to rats, fourteen metabolites were observed in the feces; whereas, only 6 metabolites were observed in urine. No glucuronides were found in either the urine or feces. Less than 1% of the dose was recovered in rat urine; whereas, up to 40% of the dose was recovered as MPC-3100 and metabolites in feces over a 24 hour period. As many as 25 different metabolites were observed in the bile based upon differences in their retention time and molecular weight. Most of the metabolites in the bile resulted from either glucuronidation or sulfation, some of which were conclusively identified with authentic standards. Rat, dog, and monkey liver microsomes all produced the four major metabolites formed in human liver microsomes. Three of these metabolites formed in human microsomes were conclusively identified by comparison to authentic synthetic standards. Although MPC-3100 and several metabolites were found in rat, dog and monkey urine, the primary route of elimination of MPC-3100 was through biliary excretion. Abstract #3237 "Evaluation of the pharmacokinetics and efficacy of a novel pro-drug of the HSP90 inhibitor, MPC-3100, designed with improved solubility"Damon Papac, J. Scott Patton, Leslie Reeves, Lynn DeMie, Chad Bradford, Brian Hachey, Brian Clemetson, Christin Christensen, Se-Ho Kim, Rajendra Tangallapally, Daniel Parker, Richard Trovato, In Chul Kim, Daniel Wettstein, Vijay R. Baichwal, Ashok Bajji. Myrexis, Salt Lake City, UTMPC-3100 is a synthetic, orally bioavailable Introduction: HSP90 inhibitor in clinical development. The low solubility of this compound requires a solubility enhancing agent to enable uniform oral bioavailability. A pro-drug of MPC-3100 with enhanced aqueous solubility was synthesized and evaluated for its physical-chemical and pharmacokinetic properties, and anti-tumor activity in mice. Methods: The alanine ester of MPC-3100 was synthesized by esterifying a hydroxyl group on the active compound, MPC-3100. Solubility and permeability were determined over the pH range of 5 - 7.5 using the PIon solubility analyzer and the double sink PAMPA method. To investigate esterase-mediated activation of the pro-drug, the pro-drug was incubated with biological matrices known to contain esterases (mouse and human plasma and liver microsomes). The pharmacokinetics of the active component of the pro-drug was determined at 360 mg/kg in female CD-1 mice after administration as an oral suspension in 2% carboxymethylcellulose (CMC). Plasma concentrations of the active compound, MPC-3100, were quantified by LC-ESI-MS/MS. Five million NCI-N87 human gastric carcinoma cells were implanted subcutaneously into athymic mice (nu/nu) to produce a mouse xenograft model. Efficacy was determined in this model using once daily oral dosing in 2% CMC for 21 days. Results: The kinetic solubility of the alanine ester pro-drug of MPC-3100 at pH 6.5 was 536 µg/mL compared to 10.2 µg/mL for MPC-3100. The pro-drug had an apparent permeability of 2.7 x 10-6 cm/sec at pH 6.2; whereas, the apparent permeability of MPC-3100 was 420 x 10-6 cm/sec. The low permeability of the pro-drug suggests conversion to active would be required to occur in the lumen prior to MPC-3100 absorption. The pro-drug was converted to MPC-3100 (half-life < 3 minutes) in mouse plasma and in mouse and human NADPH-deficient liver microsomes, but was converted slowly in human plasma with a half-life of 105 minutes, similar to the rate of non-enzymatic conversion in phosphate buffer (pH 7.4). An oral dose of 360 mg/kg of the pro-drug yielded a Cmax for MPC-3100 of 21.7 ug/mL and an AUC(0-inf) of 91.0 hr*ug/mL, which was comparable to exposures seen at efficacious doses of MPC-3100 formulated with solubility-enhancing agents. At this same dose, the pro-drug demonstrated a 42% tumor regression in the N-87 mouse xenograft model. This anti-tumor effect observed with the pro-drug was comparable to the 80% tumor regression observed with MPC-3100 at 200 mg/kg formulated with solubility-enhancing agents. ConcluThe alanine ester pro-drug of MPC-3100 had a > 50-fold increase in aqueous solubility and was converted rapidly by mouse plasma and mouse and human liver microsomes into active MPC-3100 in vitro and in vivo. These improved properties resulted in pro-drug that was efficacious in a xenograft tumor model, when dosed without a solubility enhancing agent. |
Categories
All
Archives
January 2020
|