• 1\. Sign the informed consent voluntarily and follow the program requirements

• 2\. No gender limitation;

• 3\. Age: ≥18 years old and ≤75 years old (Stage Ia);≥18 years old (Ib);

• 4\. Expected survival time ≥3 months;

• 5\. Inoperable locally advanced or metastatic HER2-positive/low-expression breast cancer and other solid tumors that have been histopathologically and/or cytologically confirmed and have failed standard therapy, or are not available for standard therapy, or are not currently eligible for standard therapy; HER2 positive: IHC3+, or IHC2+ and ISH positive; HER2 low expression: IHC2+ and ISH negative, or IHC1+;

• 6\. Agree to provide archived tumor tissue samples or fresh tissue samples from the primary tumor or metastatic tumor within 2 years (to detect the expression of HER2 protein in tumor pathological tissue and explore the correlation between HER2 protein and bl-M07D1 validity index); If subjects are unable to provide tumor tissue samples, they will be admitted after evaluation by the investigator if other admission criteria are met.

• 7\. Must have at least one measurable lesion as defined by RECIST V1.1;

• 8\. ECOG score of 0 or 1;

• 9\. Toxicity of previous antitumor therapy has returned to level ≤1 as defined by NCI-CTCAE V5.0 (the investigator considered asymptomatic laboratory abnormalities, such as elevated ALP, hyperuricemia, and elevated blood glucose, etc.); Except for toxicity that the investigator judged to have no safety risk, such as alopecia, pigmentation, grade 2 peripheral neurotoxicity, etc.);

• 10\. No serious cardiac dysfunction, left ventricular ejection fraction ≥50%;

• 11\. Organ function level must meet the following requirements and meet the following standards: A) Bone marrow function: absolute neutrophil count (ANC) ≥1.5×10\^9/L, platelet count ≥90×10\^9/L, hemoglobin ≥90 g/L; B) Liver function: total bilirubin (TBIL≤1.5 ULN), AST and ALT ≤2.5 ULN in patients without liver metastasis, AST and ALT ≤5.0 ULN in patients with liver metastasis; C) Renal function: creatinine (Cr) ≤1.5 ULN, or creatinine clearance (Ccr) ≥50 mL/min (according to the Cockcroft and Gault formula).

• 12\. Coagulation function: International standardized ratio (INR) ≤1.5, and activated partial thrombin time (APTT) ≤1.5ULN;

• 13\. Urinary protein ≤2+ or ≤1000mg/24h;

• 14\. For premenopausal women at risk of fertility, pregnancy tests must be performed within 7 days prior to the start of treatment. Serum/urine pregnancy must be negative and must be non-lactation; All enrolled patients (male and female) should use adequate barrier contraception throughout the treatment cycle and 6 months after the end of treatment