Evaluation of Enzastaurin in the Treatment of Persistent or Recurrent Ovarian or Primary Peritoneal Cancer

Inclusion Criteria:

* Participants must have recurrent or persistent epithelial ovarian or primary peritoneal carcinoma.
* All participants must have measurable disease.
* Participants must have at least one "target lesion" to be used to assess response on this protocol.
* Participants must not be eligible for a higher priority GOG protocol, if one exists.
* Participants who have received one prior regimen must have a GOG Performance Status of 0, 1, or 2. Participants who have received two prior regimens must have a GOG Performance Status of 0 or 1.
* Any hormonal therapy directed at the malignant tumor must be discontinued at least one week prior to registration. Continuation of hormone replacement therapy is permitted.
* Any other prior therapy directed at the malignant tumor, including immunologic agents, must be discontinued at least four weeks prior to registration.
* Participants must have had one prior platinum-based chemotherapeutic regimen for management of primary disease containing carboplatin, cisplatin, or another organoplatinum compound.
* Participants must NOT have received any non-cytotoxic therapy for management of recurrent or persistent disease.
* Participants of child-bearing potential must have a negative serum pregnancy test prior to study entry and be practicing an effective form of contraception (for example, intrauterine device \[IUD\], birth control pills, or barrier device) during and for 3 months after discontinuation of study treatment.

Exclusion Criteria:

* Participants with previous enzastaurin treatment.
* Participants who have received radiation to more than 25% of marrow-bearing areas
* Participants with other invasive malignancies, with the exception of non-melanoma skin cancer, who had (or have) any evidence of other cancer present within the last 5 years or whose previous cancer treatment contraindicates this protocol therapy.
* Participants who have received treatment within the last 30 days with a drug that has not received regulatory approval for any indication at the time of study entry.
* Participants who are unable to discontinue use of carbamazepine, phenobarbital, and phenytoin (refer to Concomitant Medications for a discussion of enzyme inducing anti-epileptic drugs \[EIAEDs\]).
* Participants who are receiving concurrent administration of any other systemic anticancer therapy except for a biphosphonate if patient has bony metastases.
* Participants who have received prior therapy with non-cytotoxic agents (i.e. bevacizumab).
* Participants with serious concomitant systemic disorders (for example, active infection or abnormal electrocardiogram (ECG) indicative of cardiac disease) that, in the opinion of the investigator, would compromise the safety of the patient and his/her ability to complete the study.