This is a multicenter, open-label, phase 1 study conducted to test intratumoral injections of TTI-621 in subjects that have relapsed and refractory percutaneously accessible solid tumors or mycosis fungoides.

The study will be performed in two different parts. Part 1 is the Dose Escalation phase and Part 2 is the Dose Expansion phase.

The purpose of this study is to characterize the safety profile of TTI-621 and to determine the optimal dose and delivery schedule of TTI-621. In addition, the safety and antitumor activity of TTI-621 will be evaluated in combination with other anti-cancer agents or radiation.

This is a multicenter, open-label, phase 1 study conducted to test intratumoral injections of TTI-621 in patients that have relapsed and refractory percutaneously accessible solid tumors or mycosis fungoides.

TTI-621 (SIRPα-IgG1 Fc) is a soluble recombinant fusion protein created by directly linking the sequences encoding the N-terminal CD47 binding domain of human SIRPα with the Fc domain of human immunoglobulin (IgG1). TTI-621 acts by binding human CD47 and preventing it from delivering an inhibitory "do not eat" (antiphagocytic) signal to macrophages.

The study will be performed in two different parts: Dose Escalation and Dose Expansion.

During the escalation part of the study, TTI-621 was studied at 3 different dose levels and at different dosing frequencies to characterize safety, tolerability, pharmacokinetics, and to determine the maximum tolerated dose (MTD).

During the expansion part of the study, TTI-621 will be studied in an expanded group of patients at the maximum feasible dosing regimen determined in the escalation phase. After completion of their initial assigned therapy, subjects may receive continuation with TTI-621. The expansion phase will further define safety and characterize efficacy of TTI-621 alone and in combination with other anti-cancer therapies.

Inclusion Criteria:

• Histologically or cytologically documented, injectable cancer lesion (limited to solid tumors and mycosis fungoides)
• Adequate renal function
• Adequate coagulation function
• Adequate hepatic function
• Disease that has progressed on standard therapy or for whom there is no other therapy option available

Exclusion Criteria:

• Central nervous system involvement
• Significant cardiovascular disease
• Active autoimmune disease
• Active hepatitis B or C or a history of HIV infection
• Uncontrolled infection
• History of hemolytic anemia or bleeding diathesis